demo.php

<?php

/**
 * PHP Showcase
 *
 * A single-file playground for every completion, go-to-definition, and
 * go-to-type-definition feature. Trigger completion after -> / :: / $,
 * Ctrl+Click for go-to-definition, or use "Go to Type Definition" to
 * jump to the class declaration of a variable's resolved type.
 *
 * Layout:
 *   1. DEMOS       — open any demo() method and try completion inside it
 *   2. SCAFFOLDING — supporting definitions (scroll past these)
 *
 * Priority:
 *   Basic everyday features → Trivial (works everywhere) → Advanced
 */

namespace Demo;

use Attribute;
use Closure;
use Demo\ValidationException;
use Demo\NotFoundException;
use Exception;
use Demo\UserProfile as Profile;

// ═══════════════════════════════════════════════════════════════════════════
//  DEMOS — open any demo() method and trigger completion inside
// ═══════════════════════════════════════════════════════════════════════════


// ── Auto-Import (completion) ────────────────────────────────────────────────
// Try: type `new DateT` and accept `DateTime`. The `use DateTime;` statement
// is inserted between `use Exception;` and `use Stringable;` above to
// maintain alphabetical order.
//
// The `use Exception;` import above occupies the short name "Exception".
// Try: type `throw new pq\Exception()` and accept — the auto-import inserts
// `\pq\Exception` at the usage site instead of a conflicting `use` statement.

// ── Namespace Segment Completion ────────────────────────────────────────────
// Try: erase the class name after `use Demo\` and trigger completion to see
// namespace segments (module/folder icon) alongside class names.

// ── Namespaced Function Completion ──────────────────────────────────────────
// Try: type `use function parse_file` and accept to get
// `use function ast\parse_file;`


// ── Instance Completion ─────────────────────────────────────────────────────

class InstanceCompletionDemo
{
    public function demo(): void
    {
        $zoo = new Zoo();

        $zoo->aardvark();            // own method
        $zoo->baboon;                // own property
        $zoo->buffalo;               // constructor-promoted property
        $zoo->cheetah;               // readonly promoted (from base)
        $zoo->dingo();               // trait method
        $zoo->elephant('Hi');        // trait method
        $zoo->falcon();              // inherited from parent
        $zoo->gorilla;               // @property (own class)
        $zoo->hyena('x');            // @method (own class)
        $zoo->iguana;                // @property-read (interface)
        $zoo->jaguar();              // @method (interface)
        // MUST NOT appear: $keeper (protected), $ceo (private), nocturnal() (private)
    }
}


// ── Mixed Accessor Chaining ─────────────────────────────────────────────────

class MixedAccessorDemo
{
    public function demo(): void
    {
        $foobar = new StaticPropHolder();
        $foobar->holder::$shared;                 // $obj->prop::$static chain

        // Inline (new Foo)->method() chaining
        (new Pen())->write();                     // resolves Pen then write()
    }
}

// ── Pseudo-Type Class-Name Collision ────────────────────────────────────────
// A class may be named after a PHPDoc pseudo-type such as `number` (PHP 8.4
// ships `BcMath\Number`). The class must not be shadowed by the pseudo-type.

class PseudoTypeCollisionDemo
{
    public function demo(): void
    {
        $n = new Number('42');

        $n->value;          // own property resolves (not treated as int|float)
        $n->scaled(2);      // own method resolves

        // A `Number` parameter type resolves to the class, so passing a
        // `Number` instance is accepted (no false type-mismatch diagnostic).
        scaleNumber($n);
    }
}

// ── Method & Property Chaining ──────────────────────────────────────────────

class ChainingDemo
{
    public function demo(): void
    {
        $studio = new ScaffoldingChainingDemo();

        // Fluent method chains — MUST NOT appear: calibrate() (protected)
        $studio->brush->setSize('large')->setStyle('pointed')->stroke();

        // Return type chains
        $studio->brush->getCanvas()->title();

        // Variable → method chain
        $canvas = $studio->brush->getCanvas();
        $canvas->getBrush()->stroke();

        // Deep property chain
        $studio->canvas->easel->material;
        $studio->canvas->easel->height();

        // Null-safe chaining
        $maybe = Brush::find(1);
        $maybe?->getCanvas()?->title();

        // Multi-line method chains
        $studio->brush->setSize('large')
            ->setStyle('pointed')
            ->stroke();

        // Variable assigned from chain
        $directBrush = $studio->brush->getCanvas()->getBrush();
        $directBrush->stroke();

        // (new Class())->method()
        $fromNew = (new Canvas())->getBrush();
        $fromNew->stroke();

        // Intermediate variable from property access
        $easel = (new Canvas())->easel;
        $easel->material;
    }
}


// ── Trait `return $this` Fluent Chains ──────────────────────────────────────
// A trait method whose body is `return $this;` (no declared return type)
// resolves to the class that uses the trait, so a chained call continues with
// the using class's own members — not just the trait's.

class TraitFluentChainDemo
{
    public function demo(): void
    {
        $page = new TestablePage();

        // Each step resolves to TestablePage (the using class), so the whole
        // chain — including TestablePage's own members — stays available.
        $page->assertSee('Welcome')       // trait method, body `return $this;`
            ->assertSee('Dashboard')      // still TestablePage, not the trait
            ->status;                     // using class's own property

        $page->assertSee('x')->refresh(); // using class's own method resolves
    }
}


// ── @var Docblock Override ──────────────────────────────────────────────────

class VarDocblockDemo
{
    public function demo(): void
    {
        /** @var Pencil $inlineHinted */
        $inlineHinted = getUnknownValue();
        $inlineHinted->sketch();

        /** @var Pen */
        $hinted = getUnknownValue();
        $hinted->write();                         // without variable name (PHPStorm fails this)
    }
}


// ── Return Type Resolution ──────────────────────────────────────────────────

class ReturnTypeDemo
{
    public function demo(): void
    {
        $made = Pen::make();                      // static return type → Pen
        $made->write();

        $marker = Marker::make();                 // static on subclass → Marker
        $marker->highlight();                     // resolves to Marker, not Pen

        $fluent = $marker->rename('Bold');         // rename returns static → Marker
        $fluent->highlight();                     // chained static stays on the subclass

        $created = makePen();
        $created->write();                        // function return type
        // MUST NOT appear: refill() (private)

        $absolute = \Demo\makePen();              // leading-backslash (absolute) call
        $absolute->write();                       // resolves the same as makePen()

        $found = pickPenOrPencil();               // Pen|Pencil union
        $found->label();                          // available on both types
    }
}


// ── Type Narrowing ──────────────────────────────────────────────────────────

class TypeNarrowingDemo
{
    public function demo(): void
    {
        $specimen = pickRockOrBanana();           // Rock|Banana
        if ($specimen instanceof Rock) {
            $specimen->crush();                   // narrowed to Rock
            // MUST NOT appear: peel() (Banana only)
        } else {
            $specimen->peel();                    // narrowed to Banana (else branch)
            // MUST NOT appear: crush() (Rock only)
        }

        if (!$specimen instanceof Rock) {
            $specimen->peel();                    // negated instanceof
        }

        $unknown = getUnknownValue();
        if (is_a($unknown, Rock::class)) {
            $unknown->crush();                    // is_a() narrowing
        }

        $target = getUnknownValue();
        assert($target instanceof Banana);
        $target->peel();                          // assert() narrowing

        // Inline && narrowing — RHS of && sees the narrowed type from LHS
        $sample = pickRockOrBanana();
        if ($sample instanceof Rock && $sample->crush()) {
            // $sample is Rock here too
        }

        // Short-circuit || narrowing — the right operand of || runs only
        // when the left is false, so `!$guard instanceof Rock` being false
        // means $guard IS Rock in the right operand.
        $guard = pickRockOrBanana();
        if (!$guard instanceof Rock || !$guard->crush()) {
            // guard clause body
        }
    }
}


// ── Compound & Non-Variable-Subject Narrowing ──────────────────────────────
// instanceof / assert narrowing survives compound && / || conditions and
// applies to property, array-indexed, and inline-assignment subjects, not
// just a single negated variable guard.

class CompoundNarrowingDemo
{
    public function demo(SpecimenHolder $holder): void
    {
        // && chain: a later conjunct (and the body) see the narrowing
        // established by the first conjunct.
        if ($holder->item instanceof Rock && $holder->item->crush() === 'smash!') {
            $holder->item->crush();               // property narrowed to Rock
        }

        // Heterogeneous || guard clause: De Morgan narrows the property
        // subject after the early return.
        if (!$holder instanceof SpecimenHolder || !$holder->item instanceof Rock) {
            return;
        }
        $holder->item->crush();                   // property narrowed to Rock

        // Inline assignment in the condition narrows the assigned variable.
        if (($picked = $holder->maybe()) instanceof Banana) {
            $picked->peel();                      // inline-assigned var narrowed
        }
    }

    /** @param array<Rock|Banana> $items */
    public function indexed(array $items): void
    {
        // Integer-indexed subject narrowed by a guard clause.
        if (!$items[0] instanceof Rock) {
            return;
        }
        $items[0]->crush();                       // element narrowed to Rock
    }

    public function arrow(): callable
    {
        // An untyped arrow-function parameter narrowed by an earlier `&&`
        // conjunct is visible to the member access in a later conjunct.
        return fn($specimen) => $specimen instanceof Rock && $specimen->crush() === 'smash!';
    }
}


// ── property_exists() / method_exists() Narrowing ───────────────────────────
// A member-existence guard proves the (otherwise unknown) member for the rest
// of the branch, mirroring PHPStan's `object&hasProperty(...)` intersection.
// The proof is confined to the guarded branch: the same access outside it is
// still flagged.

class MemberExistsNarrowingDemo
{
    public function property(ApiResponse $response): ?string
    {
        // property_exists() proves the dynamically-populated property, so the
        // access resolves instead of reporting an unknown member.
        if (property_exists($response, 'errorMessage') && is_string($response->errorMessage)) {
            return $response->errorMessage;       // proven by property_exists
        }
        return null;
    }

    public function guardClause(ApiResponse $response): string
    {
        // Negated guard clause: after the early return the property exists.
        if (!property_exists($response, 'detail')) {
            return 'none';
        }
        return (string) $response->detail;        // proven after the guard
    }

    public function issetGuard(ApiResponse $response): ?string
    {
        // isset($obj->prop) proves the property exists (and is non-null)
        // for the guarded branch, exactly like property_exists().
        if (isset($response->errorMessage)) {
            return (string) $response->errorMessage; // proven by isset
        }
        return null;
    }

    public function ternary(ApiResponse $response): string
    {
        // Both member-existence guards prove the property in a ternary's
        // then-branch, mirroring the if-statement form.
        $viaPropertyExists = property_exists($response, 'detail')
            ? (string) $response->detail          // proven by property_exists
            : 'none';
        $viaIsset = isset($response->errorMessage)
            ? (string) $response->errorMessage    // proven by isset
            : 'none';
        return $viaPropertyExists . '|' . $viaIsset;
    }

    public function method(DynamicHandler $handler): void
    {
        // method_exists() proves the method for the guarded branch.
        if (method_exists($handler, 'customHook')) {
            $handler->customHook();               // proven by method_exists
        }
    }
}


// ── Type Guard Narrowing (is_array, is_object, …) ──────────────────────────

class TypeGuardNarrowingDemo
{
    /**
     * @param null|list<Pen>|Pen $input
     */
    public function demo(null|array|Pen $input): void
    {
        // is_array() narrows the union to the array-like PHPDoc member,
        // preserving the generic element type for foreach iteration.
        if (is_array($input)) {
            foreach ($input as $pen) {
                $pen->write();                    // list<Pen> → Pen
            }
        }

        // Else branch: non-array members survive
        if (is_array($input)) {
            // array branch
        } else {
            // $input is null|Pen here
        }

        // Guard clause: is_array() + early return
        if (is_array($input)) {
            return;
        }
        // $input is null|Pen after the guard

        // is_object() narrows to class members only
        $mixed = pickRockOrBanana();              // Rock|Banana
        if (is_object($mixed)) {
            $mixed->weigh();                      // both Rock and Banana have weigh()
        }

        // is_object() narrows mixed → object, suppressing diagnostics
        // on dynamic property access (stdClass / object permit any property).
        $decoded = json_decode('{}');             // mixed
        if (is_object($decoded)) {
            echo $decoded->anything;              // no diagnostic — object allows any property
        }

        // Compound && condition: is_object() narrowing propagates
        // through the entire condition and into the if-body.
        $payload = json_decode('{}');             // mixed
        if (is_object($payload) && property_exists($payload, 'name')) {
            echo $payload->name;                  // no diagnostic
        }

        // A property assigned `new stdClass()` resolves back to stdClass,
        // so a nested object graph built up field by field type-checks.
        $settings = new \stdClass();
        $settings->cache = new \stdClass();       // $settings->cache : stdClass
        $settings->cache->ttl = 3600;             // no diagnostic on ->ttl
    }

    /**
     * An `array<T>|false` return keeps its element type after the false
     * check, so the surviving array still iterates to the element type.
     */
    public function falseUnion(): void
    {
        $pens = loadPensOrFail();                  // array<int, Pen>|false
        if (!is_array($pens)) {
            return;
        }
        foreach ($pens as $pen) {
            $pen->write();                        // array<int, Pen> → Pen
        }

        // The `=== false` guard narrows the same way.
        $more = loadPensOrFail();                  // array<int, Pen>|false
        if ($more === false) {
            return;
        }
        foreach ($more as $pen) {
            $pen->write();                        // array<int, Pen> → Pen
        }
    }
}


// ── instanceof self/static/parent Narrowing ────────────────────────────────

class InstanceofSelfDemo extends ScaffoldingSedan
{
    public function sport(): void {}

    public function demo(ScaffoldingMotor $m): void
    {
        // instanceof self — narrows to InstanceofSelfDemo
        assert($m instanceof self);
        $m->cruise();                             // inherited from ScaffoldingSedan
        $m->sport();                              // own method via self narrowing

        // instanceof static — narrows to InstanceofSelfDemo
        $x = getUnknownValue();
        if ($x instanceof static) {
            $x->sport();                          // narrowed to static (this class)
        }

        // instanceof parent — narrows to ScaffoldingSedan
        $y = getUnknownValue();
        if ($y instanceof parent) {
            $y->cruise();                         // narrowed to parent (ScaffoldingSedan)
        }
    }
}


// ── Custom Assert Narrowing ─────────────────────────────────────────────────

class AssertNarrowingDemo
{
    public function demo(): void
    {
        $unknown = getUnknownValue();
        assertRock($unknown);                     // @phpstan-assert Rock $value
        $unknown->crush();

        $sample = pickRockOrBanana();
        if (isRock($sample)) {                    // @phpstan-assert-if-true Rock
            $sample->crush();
        } else {
            $sample->peel();
        }

        $maybe = pickRockOrBanana();
        if (isNotRock($maybe)) {                  // @phpstan-assert-if-false Rock
            $maybe->peel();
        } else {
            $maybe->crush();
        }
    }
}


// ── Static Method Assert Narrowing ─────────────────────────────────────────

class StaticAssertNarrowingDemo
{
    public function demo(): void
    {
        // @phpstan-assert on static method — unconditional narrowing
        $unknown = getUnknownValue();
        StaticAssert::assertRock($unknown);
        $unknown->crush();                        // narrowed to Rock

        // @phpstan-assert-if-true on static method — narrows in then-branch
        $sample = pickRockOrBanana();
        if (StaticAssert::isRock($sample)) {
            $sample->crush();                     // narrowed to Rock
        }

        // @phpstan-assert-if-false on static method — narrows in else-branch
        $maybe = pickRockOrBanana();
        if (StaticAssert::isNotRock($maybe)) {
            $maybe->peel();                       // narrowed to Banana
        } else {
            $maybe->crush();                      // narrowed to Rock
        }
    }
}

// ── Inherited Assert Narrowing (PHPUnit shape) ─────────────────────────────

// The assert method is declared on the parent (StaticAssert); narrowing
// still applies when it is reached through inheritance, exactly like a
// PHPUnit test case calling the inherited `assertInstanceOf`.
class InheritedAssertNarrowingDemo extends StaticAssert
{
    public function demo(): void
    {
        // $this-> on an inherited assert method
        $viaThis = getUnknownValue();
        $this->assertRock($viaThis);
        $viaThis->crush();                        // narrowed to Rock

        // self:: on an inherited assert method
        $viaSelf = getUnknownValue();
        self::assertRock($viaSelf);
        $viaSelf->crush();                        // narrowed to Rock

        // static:: on an inherited assert method
        $viaStatic = getUnknownValue();
        static::assertRock($viaStatic);
        $viaStatic->crush();                      // narrowed to Rock
    }
}


// ── assertTrue / assertFalse Re-Export (PHPUnit shape) ─────────────────────

// PHPUnit's assertTrue()/assertFalse() carry `@phpstan-assert true/false
// $condition`, so wrapping a check in one re-exports that condition exactly
// like the bare `if` form.  assertIsObject() first narrows the mixed value
// to `object`.
class AssertConditionReexportDemo extends StaticAssert
{
    public function demo(): void
    {
        // assertIsObject() narrows mixed → object; assertTrue(property_exists())
        // then proves the dynamically-populated property.
        $model = getUnknownValue();               // mixed
        self::assertIsObject($model);             // narrowed to object
        self::assertTrue(property_exists($model, 'value'));
        echo $model->value;                       // proven by the re-exported guard

        // assertFalse() re-exports the inverse of the condition: ruling out
        // the Banana branch narrows the union to Rock.
        $subject = pickRockOrBanana();            // Rock|Banana
        self::assertFalse($subject instanceof Banana);
        $subject->crush();                        // narrowed to Rock

        // assertIsNotString() (a `@phpstan-assert !string` guard) drops the
        // string arm of a union, leaving the object.
        $mixedValue = self::pickStringOrRock();   // string|Rock
        self::assertIsNotString($mixedValue);
        $mixedValue->crush();                     // narrowed to Rock
    }

    /** @return string|Rock */
    private static function pickStringOrRock(): string|Rock
    {
        return new Rock();
    }
}


// ── Guard Clause Narrowing (Early Return / Throw) ──────────────────────────

class GuardClauseDemo
{
    public function demo(): void
    {
        $subject = pickRockOrBanana();            // Rock|Banana
        if (!$subject instanceof Banana) {
            return;                               // early return — guard clause
        }
        $subject->peel();                         // narrowed to Banana after guard

        $candidate = pickRockOrBanana();          // Rock|Banana
        if ($candidate instanceof Rock) {
            throw new Exception('no rocks');       // early throw — guard clause
        }
        $candidate->peel();                       // narrowed to Banana (Rock excluded)

        $unknown = getUnknownValue();
        if (!$unknown instanceof Rock) return;    // single-statement guard (no braces)
        $unknown->crush();                        // narrowed to Rock
    }

    /** Positive instanceof + early return on a mixed parameter. */
    public function mixedGuard(mixed $value): void
    {
        if ($value instanceof Banana) {
            return;                               // $value is Banana → exit
        }
        // After the guard, $value is NOT Banana.
        if ($value instanceof Rock) {
            $value->crush();                      // narrowed to Rock (not Banana)
        }
    }
}


// ── in_array Strict-Mode Narrowing ─────────────────────────────────────────

class InArrayNarrowingDemo
{
    /**
     * @param Rock|Banana $item
     * @param list<Rock> $rocks
     */
    public function demo($item, array $rocks): void
    {
        if (in_array($item, $rocks, true)) {
            $item->crush();                       // narrowed to Rock
            // MUST NOT appear: peel() (Banana only)
        } else {
            $item->peel();                        // excluded Rock → Banana
            // MUST NOT appear: crush() (Rock only)
        }

        // Guard clause with in_array
        $specimen = pickRockOrBanana();           // Rock|Banana
        if (!in_array($specimen, $rocks, true)) {
            return;
        }
        $specimen->crush();                       // narrowed to Rock after guard
    }
}


// ── Generics (@template / @extends) ────────────────────────────────────────

class GenericsDemo
{
    public function demo(): void
    {
        $repo = new PenRepository();
        $repo->find(1)->write();                  // Repository<Pen>::find() → Pen
        $repo->findOrNull(1)?->write();           // ?Pen

        $pens = new PenCollection();              // TypedCollection<int, Pen>
        $pens->first()->write();
        // MUST NOT appear: refill() (private on Pen)
        $pens->thickOnly();                       // own method on subclass

        $cachingRepo = new CachingPenRepository();
        $cachingRepo->find(1)->write();           // grandparent generics

        $responses = new ResponseCollection();    // @phpstan-extends variant
        $responses->first()->getStatusCode();
    }
}


// ── @implements Generic Resolution ─────────────────────────────────────────

class ImplementsGenericDemo
{
    public function demo(): void
    {
        $repo = new PenStorage();
        $repo->find(1)->write();                  // @implements Storage<Pen> → Pen

        $penCatalog = new PenCatalog();
        $penCatalog->find(1)->write();            // @template-implements alias

        $items = new ItemIterableCollection();
        foreach ($items as $item) {
            $item->write();                       // @implements IteratorAggregate<Pen>
        }
    }
}


// ── Built-in Generic Collections (ArrayIterator, SplFixedArray, etc.) ───────

class BuiltinGenericCollectionDemo
{
    /** @return \ArrayIterator<int, Pen> */
    public function getPens(): \ArrayIterator { return new \ArrayIterator([new Pen()]); }

    public function demo(): void
    {
        $pen = $this->getPens()->current();
        $pen->write();                            // ArrayIterator<int, Pen> → current() returns Pen

        // Direct chain also works:
        $this->getPens()->current()->write();     // same resolution through the chain
    }
}


// ── SimpleXMLElement Iteration (Iterator without generics) ──────────────────

class SimpleXmlIterationDemo
{
    public function demo(): void
    {
        $xml = new \SimpleXMLElement('<root><child/></root>');
        foreach ($xml->children() as $child) {
            $child->getName();                    // Iterator (no generics) → current(): static
        }
    }

    public function firstChild(): ?\SimpleXMLElement
    {
        foreach ((new \SimpleXMLElement('<root><child/></root>'))->children() as $child) {
            return $child;
        }
        return null;
    }
}


// ── SPL Wrapper Iterators (FilterIterator, DirectoryIterator) ───────────────

class SplWrapperIterationDemo
{
    public function demo(): void
    {
        // `PhpFileFilter` is `@extends FilterIterator<int, SplFileInfo,
        // \Iterator<int, SplFileInfo>>`. The value type is the middle
        // argument (SplFileInfo), not the trailing inner-iterator argument.
        $files = new PhpFileFilter(new \ArrayIterator([new \SplFileInfo(__FILE__)]));
        foreach ($files as $file) {
            $file->getRealPath();                 // FilterIterator<_, SplFileInfo, _> → SplFileInfo
        }

        // Directly-constructed SPL iterator: the value type comes from
        // `DirectoryIterator::current()`.
        foreach (new \DirectoryIterator(__DIR__) as $entry) {
            $entry->isFile();                     // DirectoryIterator → current(): DirectoryIterator
        }
    }
}


// ── Inherited Docblock Types ────────────────────────────────────────────────

class InheritedDocblockDemo
{
    public function demo(): void
    {
        // Interface declares @return list<Pen>, implementor has only `: array`.
        // The richer type propagates automatically.
        $holder = new ScaffoldingConcreteHolder();
        $holder->getPens()[0]->write();            // list<Pen> inherited from interface

        // Parent class declares @return list<Pen>, child overrides with `: array`.
        $child = new ScaffoldingChildHolder();
        $child->getPens()[0]->write();             // list<Pen> inherited from parent

        // When the child writes its own @return, it wins over the parent.
        $cat = new ScaffoldingCatStore();
        $cat->getAnimals()[0]->label();            // list<Pencil> from child's own docblock

        // Parameter types propagate by position (child may rename params).
        $box = new ScaffoldingPenBox();
        $box->accept([new Pen()]);                 // @param list<Pen> inherited from interface

        // Grandparent @return flows through the entire chain.
        $deep = new ScaffoldingDeepChild();
        $deep->getPens()[0]->write();              // list<Pen> from grandparent
    }
}


// ── Conditional Return Types ────────────────────────────────────────────────

class ConditionalReturnDemo
{
    public function demo(): void
    {
        $container = new Container();
        $resolved = $container->make(Pen::class);
        $resolved->write();                       // class-string<T> → T

        $appPen = app(Pen::class);                // conditional on standalone function
        $appPen->write();

        // Literal string conditional return type
        $mapper = new TreeMapperImpl();
        $result = $mapper->map('foo', 'bar');
        $result->write();                         // "foo" → Pen (literal string match)

        // Out-of-order named arguments bind to the parameter they name, so
        // the conditional keys on `$signature` ("foo") regardless of the
        // order the arguments appear in the call.
        $named = $mapper->map(source: 'bar', signature: 'foo');
        $named->write();                          // named "foo" → Pen

        // A conditional branch selecting `mixed` flows `mixed` through as a
        // real type, so the value stays usable (and narrowable) instead of
        // becoming untyped.
        $unknown = sessionValue('file');          // ($key is string ? mixed : null) → mixed
        if (is_string($unknown)) {
            strtoupper($unknown);                 // narrowed from mixed to string
        }
    }
}


// ── Method-Level @template ──────────────────────────────────────────────────

class MethodTemplateDemo
{
    public function demo(): void
    {
        $locator = new ServiceLocator();
        $locator->get(Pen::class)->write();               // class-string<T> → T

        // A class-string passed as a single-quoted string literal: the
        // source `\\` is a namespace-separator escape, so `'Demo\\Pen'`
        // names the class `Demo\Pen` and T resolves to Pen.
        $locator->get('Demo\\Pen')->write();              // string-literal class-string → Pen

        // A union of class-strings (iterating a class-constant array) binds
        // the bounded template `T of Pen` to the union of the concrete
        // classes, so `@return T[]` resolves to (Pen|Marker)[] instead of
        // collapsing to the bound Pen[]. Marker extends Pen, so both satisfy
        // the bound.
        foreach ([Pen::class, Marker::class] as $penClass) {
            $group = $locator->getAll($penClass);
            $group[0]->write();                           // Pen|Marker from union class-string bind
        }

        // Indexing the call result inline keeps the template binding, so
        // the `@return T[]` element resolves from the `class-string<T>`
        // argument without an intermediate variable.
        $locator->getAll(Pen::class)[0]->write();         // Pen from class-string<T> → T[] element

        Factory::create(Pen::class)->write();             // static @template
        resolve(Marker::class)->highlight();              // function @template

        $mapper = new ObjectMapper();
        $mapped = $mapper->wrap(new Pen());
        $mapped->first();                         // → Pen (T resolved from argument)

        $mapper->wrap(new Product())->first()->getPrice(); // new expression arg → Product

        // Untyped class-constant argument binds T to the constant's value
        // type (int), not the constant's owning class.
        $mapper->identity(ConstantTypeDemo::TIMEOUT); // hover → int

        // A `::class` argument binds `@param T` to the argument's actual
        // type — a class-string — so the return type is class-string<Pen>,
        // not the bare Pen instance type.
        $mapper->identity(Pen::class); // hover → class-string<Pen>

        // Chained instantiation preserves constructor-inferred generics
        (new ObjectMapper())->wrap(new Pen())->first()->write(); // (new ...)->method() chain with generics

        // Variadic class-string<T> → union return type
        $locator2 = new ServiceLocator();
        $union = $locator2->getAny(Pen::class, Marker::class);
        $union->write();                                  // A|B from variadic class-string<T>
        $union->highlight();

        // Nested generic return: @return Box<T> with class-string<T> param
        $boxed = $locator->wrap(Pen::class);
        $boxed->unwrap()->write();                        // Box<T>::unwrap() → Pen

        // A `class-string<T>|T` union parameter (the Mockery::mock()
        // shape, here nested in a variadic array hint) binds T to the
        // named class itself, so a `::class` argument and an instance
        // argument both resolve to a Pen instance.
        $locator->build(Pen::class)->write();             // class-string<T>|T with Pen::class → Pen
        $locator->build(new Pen())->write();              // class-string<T>|T with instance → Pen

        // An identity generic whose *constraint* is an array type: T is
        // never bound from an argument here, only from its declared bound.
        $mapper->peekLast([new Pen()]);
    }
}


// ── Closure Return Type Template Binding ────────────────────────────────────

class ClosureReturnTemplateDemo
{
    public function demo(): void
    {
        // Method-level @template bound from closure return type annotation.
        // reduce()'s TReduceReturnType is inferred from the closure's `: Pen` return type.
        /** @var ScaffoldingReducible<Pencil> $pencils */
        $pencils = new ScaffoldingReducible();

        $merged = $pencils->reduce(
            fn(Pen $carry, Pencil $item): Pen => $carry,
            new Pen('starter')
        );
        $merged->write();       // TReduceReturnType = Pen

        // Same with function() keyword closure
        $merged2 = $pencils->reduce(
            function(Pen $carry, Pencil $item): Pen {
                return $carry;
            },
            new Pen('starter')
        );
        $merged2->color();      // TReduceReturnType = Pen

        // Chained call: reduce() result used directly without intermediate variable.
        // The template inference must survive the symbol-map subject text serialization.
        $pencils->reduce(fn(Pen $carry, Pencil $item): Pen => $carry, new Pen('starter'))->write();

        // Closure with NO return-type annotation: the return type is
        // inferred from the body expression, resolving `$carry` from the
        // closure's own typed parameter (`$carry->rename(...)` → Pen).
        $inferred = $pencils->reduce(
            fn(Pen $carry, $item) => $carry->rename('merged'),
            new Pen('starter')
        );
        $inferred->write();     // TReduceReturnType = Pen (from the body)

        // @template T bound from a `@param \Closure(): T` callback, where the
        // closure has NO return-type annotation. The return type is inferred
        // from the closure body (like Laravel's Cache::remember).
        $cache = new ScaffoldingClosureCache();
        $cache->remember('pen', fn() => new Pen('cached'))->write();   // arrow body → Pen
        $cache->remember('marker', function () {
            return new Marker('cached');
        })->highlight();                                                // block-closure return → Marker
    }
}

// ── Closure Param → Template Inference (Contravariant) ─────────────────────

class ClosureParamTemplateDemo
{
    public function demo(): void
    {
        // When a method declares @param Closure(T): void $cb, the template
        // param T is inferred from the closure's *parameter* type annotation
        // (contravariant position), not the return type.

        $bus = new ScaffoldingEventBus();

        // Arrow function: T inferred as Pen from fn(Pen $p)
        $result = $bus->listen(function(Pen $p): void { $p->write(); });
        $result->write();       // T = Pen
        $result->color();       // completions for Pen

        // Full closure: T inferred as User from function(User $u)
        $user = $bus->listen(function(User $u): void { $u->getEmail(); });
        $user->getName();       // T = User

        // Second param position: @param Closure(int, T): void
        $proc = new ScaffoldingBatchProcessor();
        $item = $proc->process(function(int $i, Pencil $p): void { $p->sketch(); });
        $item->sketch();        // T = Pencil (from position 1)
        $item->sharpen();
    }
}


// ── Trait Generic Substitution ──────────────────────────────────────────────

class TraitGenericDemo
{
    public function demo(): void
    {
        Product::factory()->create();             // @use HasFactory<UserFactory> → UserFactory
        Product::factory()->count(5)->make();     // count() returns static, make() returns Product

        $idx = new PenIndex();                    // @use Indexable<int, Pen>
        $idx->get()->write();                     // TValue → Pen
    }
}


// ── Null-Init + Conditional Reassignment ────────────────────────────────────

class NullInitReassignDemo
{
    /** @param list<Pen> $pens */
    public function demo(array $pens): void
    {
        // Pattern 1: null-init + foreach reassignment + truthiness guard
        $found = null;
        foreach ($pens as $pen) {
            if ($pen->color() === 'blue') {
                $found = $pen;
            }
        }
        if ($found) {
            $found->write();                      // Pen from foreach reassignment
        }

        // Pattern 2: null-coalesce + guard inside foreach
        /** @var array<string, Pen> $lookup */
        $lookup = getUnknownValue();
        $keys = ['a', 'b'];
        foreach ($keys as $key) {
            $item = $lookup[$key] ?? null;
            if (!$item) { continue; }
            $item->write();                       // Pen from array access via coalesce
        }
    }
}


// ── Loop-Carried Assignment ─────────────────────────────────────────────────
// When a variable is initialized as null and reassigned inside a loop body,
// the assignment from a previous iteration is visible at the top of the loop.

class LoopCarriedAssignmentDemo
{
    /** @param list<Pen> $pens */
    public function demo(array $pens): void
    {
        // Pattern: null-init + reassignment after the usage point in the loop.
        // On the second iteration, $prev holds the Pen from the prior iteration.
        $prev = null;
        foreach ($pens as $pen) {
            if ($prev !== null) {
                $prev->write();                   // Pen from previous iteration
            }
            $prev = $pen;
        }

        // Same pattern with a while loop
        $lastOrder = null;
        while ($row = rand(0, 1)) {
            if ($lastOrder !== null) {
                $lastOrder->getStatusCode();      // Response from previous iteration
            }
            $lastOrder = new Response(200, 'ok');
        }
    }
}


// ── Assignment Inside a Condition ───────────────────────────────────────────
// A variable assigned in an `if`/`while` condition is a definition site,
// including the bare negated guard and the call-wrapped form.

class ConditionAssignmentDemo
{
    /** @return ?Pen */
    public function maybePen(): ?Pen { return rand(0, 1) ? new Pen() : null; }

    public function demo(): void
    {
        // Bare negated guard: PHP parses this as `!($pen = $this->maybePen())`.
        if (!$pen = $this->maybePen()) {
            return;
        }
        $pen->write();                            // Pen (assignment seen through `!`)

        // Assignment wrapped in a call argument.
        while (is_object($next = $this->maybePen())) {
            $next->write();                       // Pen (assignment seen inside is_object())
        }
    }
}


// ── Null Coalesce (`??`) Refinement ─────────────────────────────────────────

class NullCoalesceDemo
{
    /** @return ?Pen */
    public function maybePen(): ?Pen { return rand(0, 1) ? new Pen() : null; }

    public function demo(): void
    {
        // Non-nullable LHS: `new Foo()` can never be null, so the RHS
        // is dead code and the result resolves to Pen only.
        $a = new Pen() ?? new Marker();
        $a->write();                              // Pen (RHS ignored)

        // Nullable LHS: `?Pen` return strips null, unions with RHS.
        $b = $this->maybePen() ?? new Marker();
        $b->write();                              // Pen|Marker

        // Clone is non-nullable — RHS is dead code.
        $pen = new Pen();
        $c = clone $pen ?? new Marker();
        $c->write();                              // Pen (RHS ignored)
    }
}


// ── Foreach & Array Access ──────────────────────────────────────────────────

class ForeachArrayAccessDemo
{
    public function demo(): void
    {
        /** @var list<Pen> $members */
        $members = getUnknownValue();
        foreach ($members as $member) {
            $member->write();                     // element type from list<Pen>
        }
        $members[0]->color();                     // array access element type

        /** @var array<int, Pen> */
        $annotated = [];                          // @var without variable name
        $annotated[0]->write();                   // type from next-line annotation

        $inferred = [new Pen(), new Marker()];
        $inferred[0]->write();                    // element type inferred from literal
    }

    /**
     * An inline `@var` refines a broadly-typed parameter (here `mixed`)
     * before iterating it, so the loop variable resolves to the element
     * type even though the parameter itself carries no useful type.
     */
    public function demoRetypedParam(mixed $pens): void
    {
        /** @var iterable<Pen> $pens */
        foreach ($pens as $pen) {
            $pen->write();                        // Pen from the inline @var retype
        }
    }

    /**
     * The same inline `@var` retype works when the iterable is a method
     * chain: the annotation types the base variable, the chain resolves
     * through it, and the loop variable gets the element type.
     */
    public function demoRetypedChainBase(mixed $holder): void
    {
        /** @var ScaffoldingConcreteHolder $holder */
        foreach ($holder->getPens() as $pen) {
            $pen->write();                        // Pen via the @var-typed chain base
        }
    }
}

// ── Foreach By-Reference ────────────────────────────────────────────────────

class ForeachByReferenceDemo
{
    public function demo(): void
    {
        /** @var list<Pen> $pens */
        $pens = getUnknownValue();

        // By-reference foreach: $pen resolves to element type (Pen)
        // and is not flagged as undefined or unused.
        foreach ($pens as &$pen) {
            $pen->write();                        // Pen from list<Pen>
            $pen = new Pen();                     // reassignment through reference
        }
        unset($pen);

        // Key-value with by-reference value
        /** @var array<string, Pen> $named */
        $named = getUnknownValue();
        foreach ($named as $key => &$tool) {
            $tool->color();                       // Pen from array<string, Pen>
        }
        unset($tool);
    }
}


// ── Property Array Access (generic annotations) ────────────────────────────

class PropertyArrayAccessDemo
{
    /** @var array<string, Pen> */
    private array $cache = [];

    /** @var array<int, Pen> */
    public array $items = [];

    public function demo(): void
    {
        // Property typed as array<string, Pen> — variable key
        $this->cache[$this->getKey()]->write();   // element type from generic annotation

        // Property typed as array<string, Pen> — string-literal key
        $this->cache['brushes']->color();         // element type from generic annotation

        // Property typed as array<int, Pen> — numeric index
        $this->items[0]->write();                 // element type from generic annotation

        // Method chain after bracket access
        $this->cache['tools']->rename('Fine')->write(); // chain through element type
    }

    private function getKey(): string { return 'k'; }
}


// ── Array Destructuring ────────────────────────────────────────────────────

class ArrayDestructuringDemo
{
    public function demo(): void
    {
        /** @var list<Pen> */
        [$first, $second] = getUnknownValue();
        $first->write();                          // destructured element type
    }
}


// ── Array Shapes ────────────────────────────────────────────────────────────

class ArrayShapeDemo
{
    public function demo(): void
    {
        // Literal array shape — key completion and value types
        $config = ['host' => 'localhost', 'port' => 3306, 'tool' => new Pen()];
        $config[''];                              // Try: key completion: host, port, tool
        $config['tool']->write();                 // value type → Pen

        // Annotated shape
        /** @var array{first: Pen, second: Pencil} $pair */
        $pair = getUnknownValue();
        $pair['first']->write();
        $pair['second']->sketch();

        // Shape from function return type
        $cfg = getAppConfig();
        $cfg['logger']->write();
    }
}


// ── Object Shapes ───────────────────────────────────────────────────────────

class ObjectShapeDemo
{
    public function demo(): void
    {
        /** @var object{title: string, score: float} $item */
        $item = getUnknownValue();
        $item->title;                             // Ctrl+Click → jumps to `title:` in docblock above
        $item->score;                             // Ctrl+Click → jumps to `score:` in docblock above
    }
}


// ── Spread Operator Type Tracking ───────────────────────────────────────────

class SpreadOperatorDemo
{
    public function demo(): void
    {
        /** @var list<Pen> */
        $penList = [];
        /** @var list<Pencil> */
        $pencilList = [];

        $allPens = [...$penList];
        $allPens[0]->write();                     // resolves Pen from spread

        $everything = [...$penList, ...$pencilList];
        $everything[0]->label();                  // union: Pen|Pencil from multiple spreads
    }
}


// ── Clone Expression ────────────────────────────────────────────────────────

class CloneDemo
{
    public function demo(): void
    {
        $pen = new Pen('blue');
        $copy = clone $pen;
        $copy->write();                           // preserves Pen type
    }
}


// ── Class-String Variable Static Access ─────────────────────────────────────

class ClassStringStaticDemo
{
    public function demo(): void
    {
        $cls = Pen::class;
        $cls::make();                             // static method from Pen
    }
}


// ── Class-String Parameter Static Dispatch ──────────────────────────────────

class ClassStringParamDispatchDemo
{
    /**
     * @param class-string<\BackedEnum> $enumClass
     */
    public function demo(string $enumClass): void
    {
        // Static method dispatch through class-string<T> parameter.
        // $enumClass::from() returns static, resolved to BackedEnum.
        $result = $enumClass::from('foo');
        $result->name;                            // property from UnitEnum via BackedEnum

        // Foreach over $enumClass::cases() resolves items to BackedEnum.
        foreach ($enumClass::cases() as $item) {
            $item->value;                         // property from BackedEnum
            $item->name;                          // property from UnitEnum
        }
    }
}


// ── Ambiguous Variables ─────────────────────────────────────────────────────

class AmbiguousVariableDemo
{
    public function demo(): void
    {
        if (rand(0, 1)) {
            $ambiguous = new Lamp();
        } else {
            $ambiguous = new Faucet();
        }
        $ambiguous->turnOff();                    // available on both branches
        $ambiguous->dim();                        // available on Lamp branches
        $ambiguous->drip();                       // available on Faucet branches
    }
}


// ── Parenthesized Assignment ────────────────────────────────────────────────

class ParenthesizedAssignmentDemo
{
    public function demo(): void
    {
        $parenPen = (new Pen('red'));
        $parenPen->write();                       // resolves through parentheses
    }
}


// ── String Interpolation ────────────────────────────────────────────────────

class StringInterpolationDemo
{
    public function demo(): void
    {
        $pen = new Pen('blue');
        echo "Ink is {$pen->color()}";             // brace interpolation — full completion
        echo "Tool: $pen->ink";                    // simple interpolation
        echo 'no $pen-> here';                     // single-quoted — suppressed
    }
}


// ── Foreach over Generic Collection Classes ─────────────────────────────────

class CollectionForeachDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingCollectionForeach();

        // From method return type
        foreach ($src->allPens() as $pen) {
            $pen->write();                // via method return type → collection generics
        }

        // From new instance
        $items = new PenCollection();
        foreach ($items as $item) {
            $item->color();               // resolves to Pen via @extends generics
        }

        // From property type
        foreach ($src->pens as $pen) {
            $pen->color();                // via property type → collection generics
        }

        // From variable
        $collection = $src->allPens();
        foreach ($collection as $pen) {
            $pen->write();                // via variable assignment scanning
        }

        // Conditional @return with nested static<...> generic branches
        // (Laravel's Collection::chunk shape). Chunking yields a
        // collection of collections, so each iterated batch is itself a
        // collection whose elements are the original element type.
        /** @var TypedCollection<int, Pen> $pens */
        $pens = new TypedCollection();
        foreach ($pens->chunk(1) as $batch) {
            $batch->first()->color();     // $batch → TypedCollection<int, Pen>, first() → Pen
        }
    }
}


// ── Type Aliases (@phpstan-type / @phpstan-import-type) ─────────────────────

/**
 * @phpstan-type UserData array{name: string, email: string, pen: Pen}
 * @phpstan-type StatusInfo array{code: int, label: string, owner: User}
 * @phpstan-type UserList array<int, Profile>
 */
class TypeAliasDemo
{
    public function demo(): void
    {
        $data = $this->getUserData();
        $data['name'];                    // @phpstan-type → array shape key completion
        $data['pen']->write();            // object value → method completion

        $status = $this->getStatus();
        $status['label'];                 // StatusInfo alias → array shape keys
        $status['owner']->getEmail();     // object value → method completion

        // Type alias resolves through foreach iteration
        foreach ($this->getUsers() as $user) {
            $user->getDisplayName();      // UserList → array<int, Profile> → Profile
        }
    }

    /** @return UserData */
    public function getUserData(): array
    {
        return ['name' => 'Alice', 'email' => 'alice@example.com', 'pen' => new Pen()];
    }

    /** @return StatusInfo */
    public function getStatus(): array
    {
        return ['code' => 200, 'label' => 'OK', 'owner' => new User('Alice', 'alice@example.com')];
    }

    /** @return UserList */
    public function getUsers(): array
    {
        return [];
    }
}

/**
 * @phpstan-import-type UserData from TypeAliasDemo
 * @phpstan-import-type StatusInfo from TypeAliasDemo as AliasedStatus
 */
class TypeAliasImportDemo
{
    public function demo(): void
    {
        $user = $this->fetchUser();
        $user['email'];                   // imported UserData → array shape keys
        $user['pen']->color();            // object value → method completion

        $status = $this->fetchStatus();
        $status['code'];                  // AliasedStatus → StatusInfo → array shape keys
        $status['owner']->getName();      // object value → method completion
    }

    /** @return UserData */
    public function fetchUser(): array
    {
        return ['name' => 'Bob', 'email' => 'bob@example.com', 'pen' => new Pen()];
    }

    /** @return AliasedStatus */
    public function fetchStatus(): array
    {
        return ['code' => 404, 'label' => 'Not Found', 'owner' => new User('Bob', 'bob@example.com')];
    }
}


// ── Multi-line @return & Broken Docblock Recovery ───────────────────────────

class BrokenDocblockDemo
{
    public function demo(): void
    {
        $collection = collect([]);
        $collection->groupBy('key');             // multi-line @return resolves correctly

        // Nested conditional in the generic return collapses against the
        // argument: grouping by a string key makes the result's key type
        // `array-key`, so passing a string to `get()` type-checks cleanly
        // instead of comparing against a raw, unevaluated conditional.
        $collection->groupBy('key')->get('bucket');

        $recovered = (new BrokenDocRecovery())->broken();
        $recovered->working();                   // recovers `static` from broken @return static<
    }
}


// ── Callable / Closure Variable Invocation ──────────────────────────────────

class ClosureInvocationDemo
{
    public function demo(): void
    {
        // Closure literal with native return type hint
        $makePen = function(): Pen { return new Pen(); };
        $makePen()->write();                      // resolves Pen from closure return type

        // Arrow function literal
        $makePencil = fn(): Pencil => new Pencil();
        $makePencil()->sketch();                  // arrow fn return type

        // Docblock callable annotation
        /** @var \Closure(): Pencil $supplier */
        $supplier = getUnknownValue();
        $supplier()->sharpen();                   // @var Closure() annotation

        // Chaining after callable invocation
        $builder = function(): Pen { return new Pen(); };
        $builder()->rename('Bold')->write();      // chain after $fn()

        // Variable assigned from callable invocation
        $fromClosure = $makePen();
        $fromClosure->write();                    // $result = $fn() resolves return type

        // Immediately invoked arrow function with return type
        $result = (fn(): Pen => new Pen())();
        $result->write();                         // resolves Pen from arrow fn return type

        // Immediately invoked closure with return type
        $obj = (function(): Pencil { return new Pencil(); })();
        $obj->sketch();                           // resolves Pencil from closure return type
    }
}


// ── class-string Variable Resolution ────────────────────────────────────────

class ClassStringVarDemo
{
    public function demo(): void
    {
        // new $var where $var holds a class-string
        $cls = Pen::class;
        $pen = new $cls;
        $pen->write();                            // resolves Pen from class-string

        // $var::staticMethod() where $var holds a class-string
        $userClass = User::class;
        $found = $userClass::findByEmail('test@example.com');
        $found->getEmail();                       // resolves User from class-string static call
    }

    /**
     * A `class-string<Pen>` variable that passes through a
     * `class_exists()` guard keeps its `<Pen>` type argument, so
     * `new $className()` still resolves to `Pen`.
     */
    public function guardedInstantiation(mixed $rawName): object
    {
        /** @var class-string<Pen> */
        $className = (string) $rawName;

        if (!class_exists($className)) {
            throw new \RuntimeException('missing');
        }

        $pen = new $className();
        $pen->write();                            // resolves Pen despite the class_exists() guard
        return $pen;
    }
}


// ── iterator_to_array Resolution ────────────────────────────────────────────

class IteratorToArrayDemo
{
    public function demo(): void
    {
        /** @var \Iterator<int, Pen> $iter */
        $iter = getUnknownValue();

        $items = iterator_to_array($iter);
        $items[0]->write();                       // resolves Pen from iterator value type
    }
}


// ── Compound Negated Guard Clause Narrowing ─────────────────────────────────

class CompoundNegatedNarrowingDemo
{
    /** @param Rock|Banana|Lamp $thing */
    public function demo($thing): void
    {
        // After both negated instanceof checks exit, $thing is Rock|Banana
        if (!$thing instanceof Rock && !$thing instanceof Banana) {
            return;
        }

        $thing->weigh();                          // both Rock and Banana have weigh()
    }
}


// ── __invoke() Return Type Resolution ───────────────────────────────────────

class InvokeReturnTypeDemo
{
    public function demo(): void
    {
        // Objects with __invoke() can be called like functions.
        // PHPantom resolves the return type through __invoke().
        $formatter = new ScaffoldingFormatter();
        $formatter()->write();                    // __invoke() returns Pen

        // Try: type `$formatter->` — implemented magic methods such as
        // __invoke() and __toString() are offered for explicit calls and
        // go-to-definition, sorted below the regular methods so they never
        // appear at the top of the list.
        $formatter->__invoke()->write();          // explicit __invoke() call

        // Chaining through __invoke() return type
        $factory = new ScaffoldingPenFactory();
        $factory()->rename('Fine')->write();      // __invoke() → Pen → rename() → Pen

        // Parenthesized property invocation: ($this->prop)()
        ($this->formatter)()->write();            // resolves through __invoke()

        // Foreach over __invoke() return type with docblock
        $fetcher = new ScaffoldingPenFetcher();
        foreach ($fetcher() as $item) {
            $item->write();                       // @return Pen[] on __invoke()
        }

        // Enum from()/tryFrom() chains to instance methods
        Status::from('Active')->label();          // from() returns Status
    }

    private ScaffoldingFormatter $formatter;
}


// ── Anonymous Classes ───────────────────────────────────────────────────────

class AnonymousClassDemo
{
    public function demo(): object
    {
        return new class extends Pen {
            public string $brand;
            public function cap(): string { return ''; }
            public function demo() {
                $this->cap();                    // own method
                $this->brand;                    // own property
                $this->write();                  // inherited from Pen
                // MUST NOT appear: refill() (private — not inherited)
            }
        };
    }
}


// ── Match / Ternary / Null-Coalescing Type Accumulation ─────────────────────

class ExpressionTypeDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingExpressionType();

        // Null-coalescing
        $fallback = $src->backup ?? $src->primary;
        $fallback->getStatusCode();       // Response method

        // Match expression — shared members sort above branch-only members
        $service = match (rand(0, 1)) {
            0 => new ElasticProductReviewIndexService(),
            1 => new ElasticBrandIndexService(),
        };
        $service->index();                // on both — sorted first
        $service->reindex();              // one branch only — sorted after

        // Ternary
        $svc = rand(0, 1)
            ? new ElasticProductReviewIndexService()
            : new ElasticBrandIndexService();
        $svc->index();                    // on both — sorted first
    }
}


// ── Switch Statement Type Tracking ──────────────────────────────────────────

class SwitchDemo
{
    public function demo(string $type): void
    {
        switch ($type) {
            case 'reviews':
                $service = new ElasticProductReviewIndexService();
                break;
            case 'brands':
                $service = new ElasticBrandIndexService();
                break;
        }
        $service->index();                // on both classes
    }
}


// ── Array & Object Shapes in Methods ────────────────────────────────────────

class ShapeMethodDemo
{
    public function demo(): void
    {
        $data = $this->getToolKit();
        $data['pen']->write();            // Pen
        $data['pencil']->sketch();        // Pencil

        // Nested annotated shape
        /** @var array{meta: array{page: int, total: int}, items: list<Pen>} $response */
        $response = getUnknownValue();
        $response['meta']['page'];        // nested shape key
        $response['items'][0]->write();   // list element type

        // Nested keys inferred from literal — no annotation needed
        $config = ['db' => ['host' => 'localhost', 'port' => 3306], 'debug' => true];
        $config['db']['host'];            // Try: delete 'host' and trigger completion

        // Object shapes
        $profile = $this->getProfile();
        $profile->name;                   // Ctrl+Click → jumps to `name:` in @return docblock

        $result = $this->getResult();
        $result->tool->write();           // Ctrl+Click `tool` → jumps to `tool:` in @return docblock
        $result->meta->page;              // Ctrl+Click `meta` → jumps to `meta:` in @return docblock
    }

    /** @return array{pen: Pen, pencil: Pencil, active: bool} */
    public function getToolKit(): array { return ['pen' => new Pen(), 'pencil' => new Pencil(), 'active' => true]; }

    /** @return object{name: string, age: int, active: bool} */
    public function getProfile(): object { return (object) []; }

    /** @return object{tool: Pen, meta: object{page: int, total: int}} */
    public function getResult(): object { return (object) []; }

    /** @param array{host: string, port: int, tool: Pen} $config */
    public function fromParam(array $config): void
    {
        $config['host'];                  // string
        $config['tool']->write();         // Pen
    }

    // Indexing with a dynamic (non-literal) key resolves to the union of
    // the shape's value types.
    public function dynamicKey(string $which): void
    {
        $kit = $this->getToolKit();
        $tool = $kit[$which] ?? null;     // Pen|Pencil|bool|null
        if ($tool instanceof Pen) {
            $tool->write();               // Pen after instanceof
        }

        // A map of shapes built through a dynamic-key write reads back
        // element-by-element.
        $sums = [];
        foreach ([1, 2] as $id) {
            $sums[$id] = $this->getToolKit();
            $sums[$id]['pen']->write();   // Pen through the dynamic-key write
        }

        // Nested dynamic writes read back across the same key path.
        $report = [];
        $count = 0;
        foreach ([new Pen(), new Pen()] as $pen) {
            $report['data'][$count]['tool'] = $pen;
            $entry = $report['data'][$count]['tool'];
            $entry->write();              // Pen
            $count++;
        }
    }
}


// ── Named Key Destructuring from Array Shapes ───────────────────────────────

class DestructuringShapeDemo
{
    public function demo(): void
    {
        // Named key from method return
        ['pen' => $pen, 'pencil' => $pencil] = $this->getToolKit();
        $pen->write();                    // Pen from 'pen' key
        $pencil->sketch();                // Pencil from 'pencil' key

        // Named key from @var annotated variable
        /** @var array{pen: Pen, pencil: Pencil, active: bool} $data */
        $data = getUnknownValue();
        ['pen' => $myPen, 'pencil' => $myPencil] = $data;
        $myPen->write();                  // Pen from 'pen' key
        $myPencil->sketch();              // Pencil from 'pencil' key

        // Positional from shape
        /** @var array{Pen, Pencil} $pair */
        $pair = getUnknownValue();
        [$first, $second] = $pair;
        $first->write();                  // Pen (positional index 0)
        $second->sketch();                // Pencil (positional index 1)

        // Positional shape indexed directly with an integer literal
        $pair[0]->write();                 // Pen (positional index 0)
        $pair[1]->sketch();                // Pencil (positional index 1)

        // Positional shape spread across multiple docblock lines
        /**
         * @var array{
         *     Pen,
         *     Pencil,
         * } $multiline
         */
        $multiline = getUnknownValue();
        $multiline[0]->write();            // Pen (positional index 0)
        $multiline[1]->sketch();           // Pencil (positional index 1)

        // list() syntax
        /** @var array{recipe: Recipe, servings: int} $meal */
        $meal = getUnknownValue();
        list('recipe' => $recipe) = $meal;
        $recipe->ingredients;             // Recipe from 'recipe' key
    }

    /** @return array{pen: Pen, pencil: Pencil, count: int} */
    public function getToolKit(): array { return []; }

    public function inferredTuples(): void
    {
        // Inferred (unannotated) nested array literals keep their positional
        // arity, so the foreach element is a fixed tuple and integer-literal
        // indexing resolves each position.
        $rows = [[new Pen(), new Pencil()]];
        foreach ($rows as $row) {
            $row[0]->write();             // Pen (nested tuple index 0)
            $row[1]->sketch();            // Pencil (nested tuple index 1)
        }

        // A heterogeneous tuple indexed at a position that only some arms
        // have, combined with a `?? Class::class` fallback, keeps the value
        // a class-string instead of widening to plain string.
        $specs = [['pen', Pen::class], ['pencil']];
        foreach ($specs as $spec) {
            $toolClass = $spec[1] ?? Pencil::class;   // class-string<Pen>|class-string<Pencil>
            $tool = new $toolClass();
            $tool->label();               // Pen|Pencil created from the class-string
        }
    }
}


// ── Generic Context Preservation ────────────────────────────────────────────

class GenericContextDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingGenericContext();

        $src->chest->unwrap()->open();             // Box<Gift>::unwrap() → Gift
        $src->display()->first()->open();          // TypedCollection<int, Gift>::first() → Gift
    }
}


// ── Generic Shape Substitution ──────────────────────────────────────────────

class GenericShapeDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingGenericShape();

        // Template params inside array shape bodies are substituted through inheritance
        $result = $src->getResult();
        $result['data']->open();          // array{data: T} with T=Gift → Gift

        // Chained bracket access walks shape key then list element
        $first = $result['items'][0];
        $first->open();                   // list<T> with T=Gift → Gift
    }
}


// ── Foreach, Key Types, and Destructuring ───────────────────────────────────

class IterationDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingIteration();

        // From method
        foreach ($src->allPens() as $pen) {
            $pen->write();                // list<Pen> → Pen
        }

        // From property
        foreach ($src->batch as $pen) {
            $pen->write();
        }

        // Key types
        foreach ($src->crossRef() as $pen => $pencil) {
            $pen->write();                // Pen (key type)
            $pencil->sketch();            // Pencil (value type)
        }

        // WeakMap keys
        /** @var \WeakMap<Pen, Pencil> $mapping */
        $mapping = new \WeakMap();
        foreach ($mapping as $pen => $pencil) {
            $pen->write();                // key: Pen
            $pencil->sketch();            // value: Pencil
        }

        // Destructuring
        [$first, $second] = $src->allPens();
        $first->write();                  // destructured element type

        // Foreach destructuring
        /** @var array<int, array{string, int}> $rows */
        $rows = [['Alice', 30], ['Bob', 25]];
        foreach ($rows as [$name, $age]) {
            strlen($name);                // string from positional shape
            abs($age);                    // int from positional shape
        }

        // Foreach keyed shape destructuring
        /** @var array<int, array{tool: Pen, count: int}> $inv */
        $inv = [];
        foreach ($inv as ['tool' => $tool, 'count' => $count]) {
            $tool->write();               // Pen from keyed shape
            abs($count);                  // int from keyed shape
        }

        // Nested destructuring
        /** @var array{string, array{Pen, Pencil}} $nested */
        $nested = ['label', [new Pen(), new Pencil()]];
        [$label, [$nestedPen, $nestedPencil]] = $nested;
        strlen($label);                   // string from outer position 0
        $nestedPen->write();              // Pen from inner position 0
        $nestedPencil->sketch();          // Pencil from inner position 1
    }
}


// ── Foreach Array Shape Elements ────────────────────────────────────────────

class ForeachArrayShapeDemo
{
    /**
     * @param array<int, array{tool: Pen, count: int}> $inventory
     */
    public function demo(array $inventory): void
    {
        // When iterating over an array whose value type is an array shape,
        // the foreach variable carries the shape type so that bracket
        // access resolves each key to its declared type.
        foreach ($inventory as $entry) {
            $entry['tool']->write();      // array{tool: Pen, count: int} → Pen
        }
    }
}


// ── Variadic Parameter Foreach ──────────────────────────────────────────────

class VariadicForeachDemo
{
    public function demo(Pen ...$pens): void
    {
        // Variadic parameters are arrays: foreach extracts the element type
        foreach ($pens as $pen) {
            $pen->write();                // element type from variadic Pen ...$pens
        }
    }

    public function unionVariadic(Pen|Pencil ...$tools): void
    {
        // Union variadic: foreach value is Pen|Pencil
        foreach ($tools as $tool) {
            if ($tool instanceof Pen) {
                $tool->write();           // narrowed to Pen via instanceof
            }
        }
    }
}


// ── Array Function Type Preservation ────────────────────────────────────────

class ArrayFuncDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingArrayFunc();

        $active = array_filter($src->members, fn(Pen $pen) => $pen->color() === 'blue');
        $active[0]->write();              // Pen preserved through array_filter

        $vals = array_values($src->members);
        $vals[0]->write();                // Pen preserved through array_values

        $pens = $src->roster();
        $last = array_pop($pens);
        $last->write();                   // single Pen from array_pop

        $cur = current($src->members);
        $cur->write();                    // Pen from current()

        end($src->members)->write();      // inline end() without variable

        foreach (array_filter($src->members, fn(Pen $pen) => true) as $pen) {
            $pen->color();                // Pen preserved in foreach
        }

        $mapped = array_map(fn($pen) => $pen, $src->members);
        $mapped[0]->write();              // Pen from array_map fallback

        // Untyped callback parameter inferred from a method-call array
        // argument: `$pen` resolves to Pen from roster()'s list<Pen>.
        array_map(fn($pen) => $pen->color(), $src->roster());
        array_filter($src->roster(), fn($pen) => $pen->color() === 'blue');

        // array_reduce: return type inferred from initial value (3rd arg)
        $merged = array_reduce($src->members, function(Pen $carry, Pen $item): Pen {
            return $carry;
        }, new Pen('merged'));
        $merged->write();                 // Pen from initial value argument

        // array_sum / array_product: always int|float
        $total = array_sum([10, 20, 30]);
        $product = array_product([2, 3, 4]);
    }
}


// ── @throws Completion and Catch Variable Types ─────────────────────────────

class ExceptionDemo extends ScaffoldingException
{
    public function demo(): void
    {
        try {
            $this->riskyOperation();
        } catch (ValidationException $e) {
            $e->getMessage();             // catch variable resolves exception type
        }
    }

    /**
     * Typing `@` in this docblock suggests @throws for each uncaught exception.
     *
     * @throws NotFoundException
     * @throws ValidationException
     */
    public function findOrFail(int $id): array
    {
        if ($id < 0) {
            throw new ValidationException('ID must be positive');
        }
        $result = $this->lookup($id);
        if ($result === null) {
            throw new NotFoundException('Record not found');
        }
        return $result;
    }

    /**
     * Caught exceptions are filtered out of @throws suggestions.
     *
     * @throws AuthorizationException
     */
    public function safeOperation(): void
    {
        try {
            throw new \RuntimeException('transient error');
        } catch (\RuntimeException $e) {
            // caught — not suggested
        }
        throw new AuthorizationException('Forbidden');
    }

    /**
     * Called method's @throws propagate to the caller.
     *
     * @throws AuthorizationException
     */
    public function delegatedWork(): void
    {
        $this->safeOperation();
    }
}


// ── Constructor @param → Promoted Property Override ─────────────────────────

class ParamOverrideDemo
{
    public function demo(): void
    {
        foreach ($this->ingredients as $ingredient) {
            $ingredient->name;              // Ingredient::$name
            $ingredient->format();          // Ingredient::format()
        }
        $this->recipe->name;                // Recipe::$name
    }

    /**
     * @param list<Ingredient> $ingredients
     * @param Recipe $recipe
     */
    public function __construct(
        public array $ingredients,          // @param overrides to list<Ingredient>
        public object $recipe,              // @param overrides to Recipe
    ) {}
}


// ── Inline @var on Promoted Constructor Properties ──────────────────────────

class InlineVarPromotedDemo
{
    public function __construct(
        /** @var array<Ingredient> */
        public array $ingredients,
    ) {}

    public function demo(): void
    {
        // Inline @var on promoted property overrides the native type hint
        foreach ($this->ingredients as $ingredient) {
            $ingredient->name;              // Ingredient::$name via inline @var
            $ingredient->format();          // Ingredient::format() via inline @var
        }
    }
}


// ── Generator / Iterable Yield Type Resolution ─────────────────────────────

class GeneratorDemo
{
    public function demo(): void
    {
        // Generator<int, Pen> — value is 2nd param (Pen)
        foreach ($this->getPens() as $pen) {
            $pen->write();                // resolves to Pen
        }

        // Generator<int, Pencil, mixed, Pen> — value is still 2nd param (Pencil)
        foreach ($this->processPencils() as $pencil) {
            $pencil->sketch();            // Pencil (2nd param), not Pen (4th)
        }

        // @var annotated generator
        /** @var \Generator<int, Pen> $gen */
        $gen = $this->getPens();
        foreach ($gen as $pen) {
            $pen->write();                // Generator<int, Pen> → Pen
        }

        // iterable<Pen> — single param is the value type
        foreach ($this->iterablePens() as $pen) {
            $pen->write();
        }

        // Method chain through generator element
        foreach ($this->getPens() as $pen) {
            $pen->rename('Bold')->color();
        }
    }

    /** @return \Generator<int, Pen> */
    public function getPens(): \Generator
    {
        yield new Pen();
    }

    /** @return \Generator<int, Pencil, mixed, Pen> */
    public function processPencils(): \Generator
    {
        yield new Pencil();
    }

    /** @return iterable<Pen> */
    public function iterablePens(): iterable
    {
        return [];
    }

    /**
     * @param \Generator<int, Pencil> $pencils
     */
    public function foreachGeneratorParam(\Generator $pencils): void
    {
        foreach ($pencils as $pencil) {
            $pencil->sketch();            // @param overrides native \Generator type
        }
    }
}


// ── Generator Yield Type Inference Inside Bodies ────────────────────────────
//
// Generator<TKey, TValue, TSend, TReturn>
//
// - `yield $expr` produces TValue to the consumer. The yielded variable
//   keeps its own type (from its assignment), not the Generator annotation.
// - `$var = yield $expr` assigns TSend (the sent value) to $var. The yield
//   expression evaluates to whatever was passed via ->send().

class GeneratorYieldDemo
{
    /** @return \Generator<int, Pen> */
    public function findAll(): \Generator
    {
        // The type of $pen comes from `new Pen(...)`, not from the @return.
        // Completion on $pen-> works because the assignment is known.
        $pen = new Pen('blue');
        yield $pen;
        $pen->write();                    // resolves to Pen

        $anotherPen = new Pen('red');
        yield 0 => $anotherPen;
        $anotherPen->color();             // key => value yields also work
    }

    /** @return \Generator<int, Pen> */
    public function yieldInsideControlFlow(): \Generator
    {
        if (true) {
            $pen = new Pen('green');
            yield $pen;
            $pen->write();                // resolves inside control flow blocks
        }
    }

    /** @return \Generator<int, Pen> */
    public function chainingThroughYieldInferred(): \Generator
    {
        $pen = new Pen('black');
        yield $pen;
        $pen->rename('Bold')->color();    // chains through yielded variable
    }

    /** @return \Generator<int, string, Pencil, void> */
    public function coroutine(): \Generator
    {
        // TSend inference: $var = yield gets the 3rd Generator type param.
        // yield produces 'ready' (TValue = string) to the consumer;
        // the yield expression evaluates to whatever was ->send()'d (TSend = Pencil).
        $pencil = yield 'ready';
        $pencil->sketch();                // resolves to Pencil (TSend)
    }

    /** @return \Generator<int, string, Pencil, void> */
    public function tsendInsideNestedBlocks(): \Generator
    {
        while (true) {
            if (true) {
                $pencil = yield 'waiting';
                $pencil->sketch();        // resolves inside nested blocks
            }
        }
    }
}


// ── Template Parameter Bounds ───────────────────────────────────────────────

/**
 * @template-covariant TNode of AstNode
 */
class TemplateBoundsDemo
{
    public function demo(): void
    {
        $this->node->getChildren();       // resolves via TNode's bound: AstNode
        $this->node->getParent();
    }

    /** @var TNode */
    public $node;

    /** @param TNode $node */
    public function __construct(AstNode $node)
    {
        $this->node = $node;
    }
}


// ── Match Class-String Forwarding to Conditional Return Types ───────────────

class MatchClassStringDemo
{
    public function demo(): void
    {
        $container = new Container();

        // Match expression → class-string → conditional return
        $requestType = match (rand(0, 1)) {
            0 => ElasticProductReviewIndexService::class,
            1 => ElasticBrandIndexService::class,
        };
        $requestBody = $container->make($requestType);
        $requestBody->index();            // on both classes
        $requestBody->reindex();          // ElasticProductReviewIndexService only

        // Standalone function with @template
        $resolved = resolve($requestType);
        $resolved->index();               // on both classes

        // Inline chain
        $container->make($requestType)->index();

        // Simple class-string variable
        $cls = Pen::class;
        $pen = $container->make($cls);
        $pen->write();                    // resolves through simple $cls variable

        // Ternary class-string
        $ternary = rand(0, 1) ? Pen::class : Pencil::class;
        $obj = $container->make($ternary);
        $obj->label();                    // shared by both types
    }
}


// ── Closure Parameter Inference ─────────────────────────────────────────────

class ClosureParamInferenceDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingClosureParamInference();

        // $p is inferred as Pen from map's callable(TValue, TKey) signature
        $src->items->map(fn($p) => $p->write());

        // Closure body
        $src->items->each(function ($pen) {
            $pen->write();                // resolves to Pen
        });

        // Explicit type hint takes precedence over inference
        $src->items->map(fn(Pencil $p) => $p->sketch());

        // $this in callable param resolves to receiver, not current class
        $pipeline = new ScaffoldingPipeline();
        $pipeline->when(true, function ($pipe) {
            $pipe->send('data');          // resolves to ScaffoldingPipeline, not this demo class
        });

        // Arrow function variant
        $pipeline->tap(fn($p) => $p->through([]));

        // Function-level @template callable inference
        // array_any(@param array<TKey, TValue>, @param callable(TValue, TKey): bool)
        // $item is inferred as Pen from the array's element type via template substitution
        $holder = new ScaffoldingTemplateCallableHolder();
        array_any($holder->tools, fn($item) => $item->write() !== '');
    }

    /**
     * A declared closure-parameter union is preserved even when the
     * subject is a union of differently parameterized collections.
     *
     * @param FluentCollection<int, Pen>|FluentCollection<int, Pencil> $tools
     */
    public function unionSubject(FluentCollection $tools): void
    {
        // $item resolves to the declared union Pen|Pencil, not just the
        // first collection's element type (Pen).  label() exists on both,
        // so it resolves; hover on $item shows Pen|Pencil.
        $tools->each(function (Pen|Pencil $item): void {
            $item->label();               // resolves on both union arms
        });
    }
}


// ═══════════════════════════════════════════════════════════════════════════
//  TRIVIAL — works in most editors, included for completeness
// ═══════════════════════════════════════════════════════════════════════════


// ── Static & Enum Completion ────────────────────────────────────────────────

class StaticEnumDemo
{
    public function demo(): void
    {
        User::$defaultRole;          // static property
        User::TYPE_ADMIN;            // class constant
        User::findByEmail('a@b.c');  // static method
        User::make('Bob');           // inherited static (Model)
        User::query();               // @mixin Builder (Model)

        Status::Active;              // backed enum case
        Status::Active->label();     // enum method
        Status::Active->name;        // "Active" (from UnitEnum)
        Status::Active->value;       // "active" (from BackedEnum)
        Priority::High;              // int-backed enum
        Priority::High->name;        // "High" (from UnitEnum)
        Priority::High->value;       // 3 (from BackedEnum, int)
        Mode::Manual;                // unit enum
        Mode::Manual->name;          // "Manual" (from UnitEnum)

        // Enum case assigned to variable
        $status = Status::Active;
        $status->name;               // resolves through variable
        $status->value;

        // self::/static:: inside enum methods resolve to the enum type
        Status::defaultValue();      // self::Active->value inside enum

        // cases() returns a list of the enum's own instances, so indexing
        // it inline resolves the element back to the enum.
        Status::cases()[0]->value;   // "active" — cases()[0] is a Status
        Priority::cases()[0]->name;  // "Low" — cases()[0] is a Priority
    }
}


// ── Signature Help ──────────────────────────────────────────────────────────

class SignatureHelpDemo
{
    public function demo(): void
    {
        // Place cursor inside parentheses to see parameter hints.
        // The active parameter updates as you type commas.
        $user = new User('Alice', 'alice@example.com');
        createUser('Alice', 'alice@example.com');  // standalone function
        $user->setStatus(Status::Active);          // instance method
        User::findByEmail('alice@example.com');    // static method
        new User('Bob', 'bob@example.com');        // constructor

        // Chains resolve through return types and properties:
        $user->getProfile()->setBio('Hello');                       // method return chain
        (new User('X', 'x@x.com'))->setStatus(Status::Active);     // (new ...)->method
        new User('X', 'x@x.com')->setStatus(Status::Active);     // PHP 8.4 style

        // Default values appear in parameter labels (e.g. "int $page = 1"):
        $svc = new ScaffoldingSignatureHelp();
        $svc->paginate(2, 50);

        // Per-parameter @param descriptions appear next to each parameter.
        // When the effective docblock type differs from the native PHP type
        // the description is prefixed with the effective type:
        $svc->search('php', 1, 25);
    }
}


// ── Callable Snippet Insertion ──────────────────────────────────────────────

class SnippetInsertionDemo
{
    public function demo(): Response
    {
        // Completion inserts snippets with tab-stops for required params
        $user = new User('Alice', 'alice@example.com');
        $user->setName('Bob');                    // → setName(${1:$name})
        $user->toArray();                         // → toArray()  (no params)
        $user->addRoles();                        // → addRoles() (variadic — no tab-stops)
        User::findByEmail('a@b.c');               // → findByEmail(${1:$email})
        return new Response(200);                 // → Response(${1:$statusCode})
    }
}


// ── Go-to-Definition ────────────────────────────────────────────────────────
// All jump targets are defined right after the demo so Ctrl+Click lands
// within a few lines, making it easy to verify the feature works.
//
// Member names deliberately collide with names elsewhere in the file
// (label, format, CONNECTION, $defaultRole) so a wrong-target bug
// would land on the wrong label() or CONNECTION instead of silently passing.

class GoToDefinitionDemo
{
    public function demo(): void
    {
        // Ctrl+Click on any symbol to jump to its definition
        $target = new GtdTarget();
        $target->label();                         // Ctrl+Click → GtdTarget::label() (not Pen::label)
        $target->format();                        // Ctrl+Click → GtdTarget::format() (not User::format)
        GtdTarget::FORMAT;                        // Ctrl+Click → class constant (not Renderable::format)
        GtdParent::CONNECTION;                    // Ctrl+Click → GtdParent (not Model::CONNECTION)
        GtdTarget::$defaultRole;                  // Ctrl+Click → GtdTarget (not User::$defaultRole)

        $helper = gtdHelper();
        echo $helper;                             // Ctrl+Click on $helper → jumps to assignment

        define('APP_VERSION', '1.0.0');
        echo APP_VERSION;                         // BUG: Ctrl+Click should jump to define() above
    }
}

class GtdParent { public const string CONNECTION = 'gtd'; }
class GtdTarget extends GtdParent
{
    public static string $defaultRole = 'gtd';
    public const string FORMAT = 'gtd';
    public function label(): string { return 'gtd'; }
    public function format(): string { return 'gtd'; }
}
function gtdHelper(): GtdTarget { return new GtdTarget(); }


// ── Type Hint Go-to-Definition ──────────────────────────────────────────────
// Ctrl+Click on class names in type hints, return types, catch blocks,
// and docblock annotations to jump to their definitions.
// All referenced types are defined right after the demo so the jump is short.
//
// Support classes have format()/label() methods that collide with names
// elsewhere — if GTD resolves the wrong class, you land on the wrong one.

class TypeHintGtdDemo
{
    public function demo(): void
    {
        // Catch block exception types — Ctrl+Click GtdNotFoundException or GtdAccessException
        try {
            $this->paramTypes(new GtdAlpha());
        } catch (GtdNotFoundException|GtdAccessException $e) {}
    }

    public function paramTypes(GtdAlpha $item): GtdAlpha { return $item; }                             // Ctrl+Click GtdAlpha
    public function unionTypes(GtdAlpha|GtdBeta $item): GtdAlpha|GtdBeta { return $item; }             // Ctrl+Click either
    public function intersectionTypes(GtdShape&GtdColor $item): GtdShape&GtdColor { return $item; }    // Ctrl+Click either
    public function returnType(): GtdResult { return new GtdResult(); }                                // Ctrl+Click GtdResult

    /**
     * @param list<GtdAlpha> $items                Ctrl+Click GtdAlpha
     * @return GtdResult                           Ctrl+Click GtdResult
     * @throws GtdNotFoundException                Ctrl+Click GtdNotFoundException
     */
    public function docblockTypes($items) { return $items; }

    /**
     * Callable types in docblocks. Ctrl+Click on any class name inside the
     * callable signature to jump to its definition. Hover shows the class
     * info instead of treating the whole callable as one token.
     *
     * @param \Closure(GtdAlpha): GtdResult $transform      Ctrl+Click GtdAlpha or GtdResult
     * @param callable(GtdAlpha, GtdBeta): GtdResult $merge Ctrl+Click any of the three
     * @return callable(): GtdResult                         Ctrl+Click GtdResult
     */
    public function callableDocblockTypes($transform, $merge) { return $merge; }
}

class GtdAlpha { public function label(): string { return 'alpha'; } }
class GtdBeta { public function label(): string { return 'beta'; } }
interface GtdShape { public function format(): string; }
interface GtdColor { public function format(): string; }
class GtdResult { public function label(): string { return 'ok'; } }
class GtdNotFoundException extends \RuntimeException {}
class GtdAccessException extends \RuntimeException {}


// ── Go-to-Type-Definition ───────────────────────────────────────────────────
// "Go to Type Definition" jumps to the *type's* class declaration, not the
// variable's definition site. Compare with regular Go-to-Definition:
//   • Go-to-Definition on $user   → jumps to the $user = ... assignment
//   • Go-to-Type-Definition on $user → jumps to class User { ... }
//
// Try: place the cursor on $target, $result, or $pet below and invoke
// "Go to Type Definition" (often bound to a secondary shortcut or
// right-click menu). Union types produce a peek list with all classes.

class GoToTypeDefinitionDemo
{
    public function demo(): void
    {
        $target = new GtdTarget();
        $target;                                  // Type Definition → GtdTarget

        $result = $this->getResult();
        $result;                                  // Type Definition → GtdResult

        $pet = $this->getPet();
        $pet;                                     // Type Definition → GtdAlpha | GtdBeta (two locations)

        $this;                                    // Type Definition → GoToTypeDefinitionDemo
    }

    public function getResult(): GtdResult { return new GtdResult(); }

    /** @return GtdAlpha|GtdBeta */
    public function getPet(): GtdAlpha|GtdBeta { return new GtdAlpha(); }
}


// ── Go-to-Implementation ────────────────────────────────────────────────────
// All implementors are defined right after the demo so "Go to Implementations"
// lands within a few lines.
//
// The interface method is format() — same name as Renderable::format(),
// User::format(), Ingredient::format(). A resolver bug would jump to one
// of those instead of the local implementor.

class GoToImplementationDemo
{
    // Right-click → "Go to Implementations" on GtdPrintable
    // to jump to GtdPlainPrinter and GtdHtmlPrinter below.
    // Try: Go-to-Implementation on "format" → format() in each implementor
    public function demo(GtdPrintable $printer): string
    {
        return $printer->format();
    }
}

interface GtdPrintable { public function format(): string; }
class GtdPlainPrinter implements GtdPrintable { public function format(): string { return 'plain'; } }
class GtdHtmlPrinter implements GtdPrintable { public function format(): string { return '<b>html</b>'; } }


// ── Reverse Go-to-Implementation ────────────────────────────────────────────
// Go-to-Implementation also works in reverse: from a concrete method back to
// the interface or abstract method it satisfies.

class ReverseImplementationDemo implements GtdPrintable
{
    // Try: Go-to-Implementation on "format" below → jumps to
    // GtdPrintable::format() (the interface prototype).
    public function format(): string
    {
        return 'reverse';
    }
}


// ── Type Hierarchy ──────────────────────────────────────────────────────────
// Right-click a class/interface name → "Show Type Hierarchy" to see its
// supertypes (parent class, implemented interfaces) and subtypes (classes
// that extend or implement it).
//
// Try on GtdPrintable: supertypes → (none), subtypes → GtdPlainPrinter, GtdHtmlPrinter, ReverseImplementationDemo
// Try on ReverseImplementationDemo: supertypes → GtdPrintable, subtypes → (none)
// Try on User: supertypes → Model, Renderable, subtypes → AdminUser
// Try on Model: supertypes → (none), subtypes → User, ClassFilteringDemo, HoverOriginsDemo


// ── Context-Aware Class Name Filtering ──────────────────────────────────────
// Try: erase the class name after each keyword and re-trigger completion.
//
// extends Model        → classes only, non-final
//                        MUST show: User, Response, Pen (non-final classes)
//                        MUST NOT show: AdminUser (final), Model (abstract),
//                        Renderable (interface), HasTimestamps (trait), Status (enum)
//
// extends Renderable   → interfaces only (interface-extends-interface)
//                        MUST show: Renderable, GtdShape, Printable
//                        MUST NOT show: User (class), HasTimestamps (trait), Status (enum)
//
// implements Renderable → interfaces only
//                        MUST show: Renderable, GtdShape, Printable
//                        MUST NOT show: User (class), HasTimestamps (trait), Status (enum)
//
// use HasTimestamps    → traits only (inside class body)
//                        MUST show: HasTimestamps, HasSlug, JsonSerializer
//                        MUST NOT show: User (class), Renderable (interface), Status (enum)
//
// instanceof User      → classes, interfaces, enums (no traits)
//                        MUST show: User, Renderable, Status
//                        MUST NOT show: HasTimestamps (trait)
//
// new User             → concrete non-abstract classes only
//                        MUST show: User, Pen, Response
//                        MUST NOT show: Model (abstract), AdminUser (final is ok for new),
//                        Renderable (interface), HasTimestamps (trait), Status (enum)

class ClassFilteringDemo extends Model implements Renderable
{
    use HasTimestamps;
    public function test(): bool { return $this instanceof User; }
    public function format(string $template): string { return ''; }
    public function toArray(): array { return []; }
}


// ── Type Hint Completion in Definitions ─────────────────────────────────────
// Try: trigger completion when typing a type hint — PHP scalars (string,
// int, float, bool) appear alongside class names, with no constants or
// functions in the list. Traits are excluded because they cannot be used
// as type hints in PHP (the type check always fails at runtime).
//
// The same filtering applies in PHPDoc type positions: @param, @return,
// and @var exclude traits, while @throws uses Throwable-filtered
// completion (only exception classes and Throwable interfaces).

function typeHintDemo(User $user, string $name): string { return $user->displayName . $name; }

function unionDemo(string|int $value, ?User $maybe): string { return $maybe . $maybe->displayName; }


// ── $_SERVER Superglobal ────────────────────────────────────────────────────

class ServerSuperglobalDemo
{
    public function demo(): void
    {
        $_SERVER[''];   // Try: key completion for REQUEST_METHOD, HTTP_HOST, etc.
    }
}


// ═══════════════════════════════════════════════════════════════════════════
//  ADVANCED — specialized features
// ═══════════════════════════════════════════════════════════════════════════


// ── Intersection Types ──────────────────────────────────────────────────────

class IntersectionDemo
{
    public function demo(Envelope&Printable $item): void
    {
        $item->print();                       // from Printable
        $item->seal();                        // from Envelope
    }

    /**
     * A parenthesized "DNF" return type `(A&B)|null` resolves to the
     * intersection instead of being discarded, so after a null check
     * both interfaces' members are available on the result.
     *
     * @return (Envelope&Printable)|null
     */
    public function sealed(): ?Envelope
    {
        return openSealedEnvelope();
    }

    public function useSealed(): void
    {
        $item = $this->sealed();
        $item?->print();                      // from Printable, via the DNF return type
        $item?->seal();                       // from Envelope
    }
}


// ── Ternary Narrowing ──────────────────────────────────────────────────────

class TernaryNarrowingDemo
{
    public function __construct(private Pen|Pencil $tool) {}

    public function demo(): void
    {
        // Variable subject: narrowed to Rock (then) / Banana (else)
        $thing = pickRockOrBanana();
        $thing instanceof Rock ? $thing->crush() : $thing->peel();
    }

    /**
     * instanceof in a ternary condition narrows the `$this->tool` property
     * subject inside the then-branch, so `->write()` (declared only on Pen)
     * resolves. Because the then-branch resolves, the ternary type is the
     * union of both branches (`string|null`), not just the else-branch.
     */
    public function toolLabel(): ?string
    {
        return $this->tool instanceof Pen
            ? $this->tool->write()            // narrowed to Pen inside the ternary
            : null;
    }

    /**
     * A truthy ternary condition narrows a repeated nullable method-call
     * subject to its non-null type inside the then-branch.
     */
    public function repeatedCall(): ?string
    {
        return $this->maybePen()
            ? $this->maybePen()->write()      // narrowed to Pen (null stripped)
            : null;
    }

    private function maybePen(): ?Pen
    {
        return $this->tool instanceof Pen ? $this->tool : null;
    }
}


// ── Class Alias ─────────────────────────────────────────────────────────────

class ClassAliasDemo
{
    public function demo(): void
    {
        $profile = new Profile(new User('Eve', 'eve@example.com'));
        $profile->getDisplayName();               // Profile → UserProfile via `use ... as`
    }
}


// ── self::class / static::class ─────────────────────────────────────────────

class SelfClassDemo
{
    public function demo(): string
    {
        return self::class;          // resolves to SelfClassDemo
    }
}


// ── Trait insteadof / as Conflict Resolution ────────────────────────────────

class TraitConflictDemo
{
    use JsonSerializer, XmlSerializer {
        JsonSerializer::serialize insteadof XmlSerializer;
        XmlSerializer::serialize as serializeXml;
        JsonSerializer::serialize as private internalSerialize;
    }

    public function demo(): void
    {
        $this->internalSerialize();       // aliased as private
        $this->serialize();               // JsonSerializer wins via insteadof
        $this->serializeXml();            // XmlSerializer::serialize aliased
        $this->toJson();                  // non-conflicting from JsonSerializer
        $this->toXml();                   // non-conflicting from XmlSerializer
    }
}


// ── unset() Tracking ────────────────────────────────────────────────────────

class UnsetDemo
{
    public function demo(): void
    {
        $pen = new Pen('blue');
        $pen->write();                    // resolves to Pen
        unset($pen);
        // Try: $pen->  — no completions (variable was unset)

        // Re-assigning after unset restores type
        $tool = new Pen('red');
        unset($tool);
        $tool = new Marker();
        $tool->highlight();               // resolves to Marker

        // unset only affects targeted variable
        $pen2 = new Pen('green');
        $pencil = new Pencil();
        unset($pen2);
        $pencil->sketch();                // still resolves to Pencil
    }
}


// ── First-Class Callable Syntax (PHP 8.1) ───────────────────────────────────

class FirstClassCallableDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingFirstClassCallable();

        $fun = makePen(...);
        $fun()->write();                   // function reference → Closure returning Pen

        $orderFn = $src->dispatch(...);
        $orderFn()->write();              // instance method → Closure returning Pen

        $finder = Pen::make(...);
        $finder()->color();               // static method → Closure returning Pen

        $make = makePen(...);
        $pen = $make();
        $pen->color();                    // assigned result from callable invocation

        // Immediate invocation: method(...)() returns the method's return type
        makePen(...)()->write();          // function first-class callable invoked immediately
        Pen::make(...)()->color();        // static method first-class callable invoked immediately
        $src->dispatch(...)()->write();   // instance method first-class callable invoked immediately

        $immediate = Pen::make(...)();
        $immediate->color();              // assigned result from immediate static callable invocation
    }
}


// ── Array Element Access from Assignments ───────────────────────────────────

class ArrayAccessDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingArrayAccess();

        $pens = $src->fetchAll();         // Pen[] from method return
        $pens[0]->write();                // resolves to Pen

        $gifts = (new ScaffoldingGenericContext())
            ->display();
        $gifts[0]->open();                // resolves to Gift (element of Gift[])

        $first = $pens[0];
        $first->color();                  // resolves via $first = $pens[0]

        // Inline method-return array access (no intermediate variable)
        $src->fetchAll()[0]->write();     // resolves Pen from Pen[] return type
        $src->fetchAll()[0]->color();     // same, different member
    }
}


// ── Indexing an ArrayAccess Object ───────────────────────────────────────────
// `$obj[$key]` on a class implementing ArrayAccess natively resolves through
// offsetGet(), whether the value type comes from a generic docblock
// annotation or from offsetGet()'s own declared return type.

class ArrayAccessObjectDemo
{
    public function demo(): void
    {
        $pens = new ScaffoldingPenArrayAccess();
        $pens[0]->write();                // resolves via offsetGet(): Pen

        $shapes = new ScaffoldingGenericArrayAccess([new Pen()]);
        $shapes[0]->write();              // resolves via @implements \ArrayAccess<int, T>, T bound to Pen
    }
}


// ── Closure / Arrow-Function Members ────────────────────────────────────────

class ClosureMembersDemo
{
    public function demo(): void
    {
        $typedClosure = function(Pen $pen): string { return $pen->write(); };
        $typedClosure->bindTo($this);     // resolves to Closure::bindTo
        $typedClosure->call($this);       // resolves to Closure::call

        $typedArrow = fn(int $posX): float => $posX * 1.5;
        $typedArrow->bindTo($this);       // resolves to Closure::bindTo

        $fun = function(): void {};
        $bound = $fun->bindTo($this);
        $bound->call($this);             // chained: $bound is still Closure
    }
}


// ── Deprecation Messages ────────────────────────────────────────────────────
// Hover over deprecated members to see the message text from @deprecated.
// When @see tags are present alongside @deprecated, the diagnostic message
// includes the @see references so you know what to migrate to.
// Completion shows deprecated items with strikethrough styling.

class DeprecationDemo
{
    public function demo(): void
    {
        $src = new ScaffoldingDeprecation();

        // Diagnostic: "'sendLegacy' is deprecated: Use sendAsync() instead.
        //   (see: ScaffoldingDeprecation::sendAsync())"
        $src->sendLegacy();

        // Diagnostic: "'oldProcess' is deprecated: See: ScaffoldingDeprecation::sendAsync()"
        // (bare @deprecated + @see → "See:" becomes the main text)
        $src->oldProcess();

        // Diagnostic includes @see reference for the property too
        $src->debugMode;

        // Diagnostic includes @see reference for the constant
        ScaffoldingDeprecation::OLD_LIMIT;

        // Hover on any constant: shows its value inline (e.g. const MAX_LIMIT = 500;)
        ScaffoldingDeprecation::MAX_LIMIT;

        // ── #[Deprecated] attribute ─────────────────────────────────
        // PHPantom reads #[Deprecated] from both phpstorm-stubs
        // (\JetBrains\PhpStorm\Deprecated with reason:/since:) and
        // native PHP 8.4 (\Deprecated with message:/since:).

        // JetBrains stubs style: reason: + since:
        $src->attrDeprecatedMethod();

        // Native PHP 8.4 style: message: + since:
        $src->nativeDeprecatedMethod();

        // Bare #[Deprecated] (no arguments)
        $src->attrBareMethod();

        // Positional reason: #[Deprecated("...")]
        $src->attrPositionalMethod();

        // Attribute on property
        $src->attrProp;

        // Attribute on constant
        ScaffoldingDeprecation::ATTR_OLD;

        // Docblock @deprecated wins when both are present
        $src->bothDocAndAttr();

        // ── Version-aware suppression ───────────────────────────────
        // When #[Deprecated(since: "X.Y")] declares a version and your
        // project targets an older PHP version (via composer.json or
        // .phpantom.toml), the deprecation diagnostic is suppressed.
        // For example, if you target PHP 8.0:
        //   - attrDeprecatedMethod() (since: "8.1") → suppressed
        //   - nativeDeprecatedMethod() (since: "8.4") → suppressed
        //   - sendLegacy() (@deprecated docblock, no since) → still shown

        // ── Replacement code action ─────────────────────────────────
        // When #[Deprecated(replacement: "...")] provides a template,
        // placing the cursor on the call and pressing the quick-fix
        // shortcut offers "Replace with `newFunc(...)`".
        // Template variables: %parametersList%, %parameter0%, %class%.
        $src->legacySetTimezone('UTC');
    }
}


// ── Hover: Origin Indicators ────────────────────────────────────────────────

class HoverOriginsDemo extends Model implements Renderable
{
    public function demo(): void
    {
        // Hover on `format` → "◆ implements Renderable"
        $this->format('earth');

        // Hover on `toArray` → "↑ overrides Model"
        $this->toArray();

        // Hover on `getName` → no indicator (inherited, not overridden)
        $this->getName();
    }

    // Implements Renderable (Model has no format method)
    public function format(string $template): string { return ''; }

    // Overrides the abstract toArray() from Model
    public function toArray(): array { return []; }
}



// ── Diagnostic: Unknown Class ───────────────────────────────────────────────
// `MutateArrayInsertSpec` and `Cluster` below are not imported and cannot be
// resolved — they get a yellow "Class 'X' not found" warning underline.
// This diagnostic fires for any ClassReference that PHPantom cannot resolve
// through use-map, local classes, same-namespace, class_index, classmap,
// PSR-4, or stubs.  It pairs with the "Import Class" code action: press
// Ctrl+. (Cmd+. on Mac) on the warning to import the class in one step.

// ── Code Action: Import Class ───────────────────────────────────────────────
// Place cursor on `MutateArrayInsertSpec` and press Ctrl+. (or Cmd+. on Mac)
// to see "Import `Couchbase\MutateArrayInsertSpec`" in the quick-fix menu.
// Accepting inserts a `use Couchbase\MutateArrayInsertSpec;` at the top.
//
// Because this file has two unresolved names, the quick-fix menu also shows
// "Import all missing classes" which imports both at once.

class ImportClassDemo
{
    public function demo(): void
    {
        // Ctrl+. on `MutateArrayInsertSpec` → offers to import
        $spec = new MutateArrayInsertSpec('path', ['value']);

        // Ctrl+. on `Cluster` → offers to import Couchbase\Cluster
        Cluster::connect('couchbase://localhost');
    }
}


// ── Code Action: Remove Unused Import ───────────────────────────────────────
// The `use ReflectionClass;` below is unused — it appears dimmed in the editor.
// Place cursor on it and press Ctrl+. → "Remove unused import 'ReflectionClass'"

use ReflectionClass;

class RemoveUnusedImportDemo
{
    public function demo(): void
    {
        // ReflectionClass is deliberately NOT used here so its import stays dimmed.
        // Ctrl+. on the dimmed `use ReflectionClass;` above → remove it.
        $x = 42;
    }
}


// ── Diagnostic: Unknown Member Access ───────────────────────────────────────
// When PHPantom resolves the subject type but the member does not exist after
// full resolution (inheritance, traits, virtual members), a yellow "Method
// 'X' not found on class 'Y'" warning appears.  Suppressed when __call,
// __callStatic, or __get magic methods are present on the resolved class.

class UnknownMemberDemo
{
    public function demo(): void
    {
        $user = new User('test', 'test@example.com');

        // These resolve fine — no warning:
        $user->getEmail();
        $user->getName();

        // Try: uncomment the next line to see the warning:
        $user->nonexistentMethod();

        // Static access — unknown constant gets a warning:
        User::MISSING_CONST;
    }
}


// ── PHPDoc Block Generation ─────────────────────────────────────────────────
// Typing `/**` above a declaration generates a docblock skeleton.  Tags are
// only emitted when the native type hint needs enrichment: missing types get
// @param/${mixed}, bare `array` gets a placeholder, and classes with @template
// parameters get generic type tab stops (e.g. Collection<TKey, TValue>).
// Fully-typed scalar params/return types are skipped.  Properties and
// constants always get @var.  Uncaught exceptions always get @throws.
// No special treatment for overrides.

class PhpDocGenerationDemo extends ScaffoldingException
{
    public const int MAX_ITEMS = 100;
    const LABEL = 'demo';

    public string $title = '';
    public $description;

    public function demo($data, array $items, Closure $handler, callable $fallback, TypedCollection $primary, string $boring, TypedCollection $secondary): array
    {
        try {
            throw new ValidationException('Invalid id');
        } catch (ValidationException $e) {
            // Caught — should NOT appear in @throws.
        }

        /** @throws NotFoundException */
        getUnknownValue();

        $this->throwsException();

        return [];
    }
}


// Class-level @extends with template tab stops.  The parent TypedCollection
// has @template TKey and @template TValue, so typing `/**` above this class
// generates `@extends TypedCollection<TKey, TValue>` with tab stops.
// Try: type `/**` above this class.
class DocGenExtendsDemo extends TypedCollection
{
    public function customMethod(): void {}
}


// ── Diagnostic: Scalar Member Access ────────────────────────────────────────
// Accessing a property or calling a method on a scalar type (int, string,
// bool, float, null, void, never) is always a runtime error.  PHPantom flags
// these with an Error-severity diagnostic, including through method-return
// chains.

class ScalarMemberAccessDemo
{
    public function demo(User $user): void
    {
        // getName() returns string — accessing a method on it is an error:
        $user->getName()->trim();

        // getEmail() returns string — property access is also an error:
        $user->getEmail()->length;

        // Chains through intermediate classes work too:
        $user->getProfile()->getDisplayName()->toUpper();

        // Works with Response too — isSuccess() returns bool:
        $resp = new Response(200, 'OK');
        $resp->isSuccess()->flag;
    }
}


// ── Diagnostic: Unresolved Member Access (opt-in) ───────────────────────────
// When PHPantom cannot resolve the *subject type* of a member access at all,
// it can show a hint-level diagnostic.  This is off by default because most
// codebases lack full type coverage.  Enable it in .phpantom.toml:
//
//   [diagnostics]
//   unresolved-member-access = true
//
// This is useful for discovering gaps in type coverage or places where
// PHPantom's inference falls short.

class UnresolvedMemberAccessDemo
{
    public function demo(): void
    {
        // $mystery has type "mixed" — PHPantom cannot resolve it.
        // With the diagnostic enabled, a hint appears on the next line:
        $mystery = getUnknownValue();
        $mystery->doSomething();
    }
}


// ── Diagnostic: Argument Count ──────────────────────────────────────────────
// PHPantom flags calls that pass too few or too many arguments.  Variadic
// parameters accept unlimited trailing args.  Argument unpacking (`...$args`)
// suppresses the diagnostic because the actual count is unknown statically.

class ArgumentCountDemo
{
    public function demo(): void
    {
        $user = new User('Alice', 'alice@test.com');

        // Correct — no diagnostic:
        $user->getEmail();
        $user->setName('Bob');
        $user->addRoles('admin', 'editor', 'viewer'); // variadic

        // Too few arguments — error diagnostic appears:
        $user->setStatus();

        // Too many arguments — error diagnostic appears:
        $user->getEmail('extra');
    }
}

class TypeErrorDemo
{
    public function demo(): void
    {
        $user = new User('Alice', 'alice@test.com');

        // Correct — no diagnostic:
        $user->setName('Bob');
        $user->setStatus(Status::Active);

        // Type error — string passed to int parameter:
        $this->requiresInt("not a number");

        // Type error — null passed to non-nullable parameter:
        $this->requiresString(null);

        // Type error — wrong class type:
        $pen = new Pen('blue');
        $this->requiresUser($pen);

        // No diagnostic — subclass is compatible:
        $admin = new AdminUser('Admin', 'admin@test.com', ['manage']);
        $this->requiresUser($admin);

        // No diagnostic — null is valid for nullable parameter:
        $this->acceptsNullable(null);
        $this->acceptsNullable("hello");

        // No diagnostic — int widens to float:
        $this->requiresFloat(42);
    }

    private function requiresInt(int $value): void {}
    private function requiresString(string $text): void {}
    private function requiresUser(User $user): void {}
    private function acceptsNullable(?string $text): void {}
    private function requiresFloat(float $value): void {}
}


// ── Implement Missing Methods (Code Action) ─────────────────────────────────
// Uncomment the class below, place the cursor inside it, and trigger
// "Quick Fix" or "Code Action" to see "Implement 3 missing methods".
// The generated stubs include correct visibility, parameter types, defaults,
// and return types.  Re-comment when done (PHP fatals on unimplemented
// abstract methods).

// class ImplementMethodsDemo extends ScaffoldingAbstractShape implements ScaffoldingDrawable
// {
// }


// ── Generate Constructor (Code Action) ──────────────────────────────────────
// Place the cursor inside the class below and trigger "Code Action" to see
// "Generate constructor".  The generated constructor includes a parameter
// and assignment for each non-static property.  Readonly properties are
// included because they must be initialized in the constructor.  Default
// values are carried over and required parameters are placed before
// optional ones.

class GenerateConstructorDemo
{
    public int $age;
    public string $name;
    public string $status = 'active';
    public ?string $email;
    public readonly string $id;
    public static int $instanceCount;     // excluded (static)
}


// ── Generate Getter/Setter (Code Action) ────────────────────────────────────
// Place the cursor on a property declaration below and trigger "Code Action"
// to see "Generate getter", "Generate setter", and "Generate getter and
// setter".  Bool properties use an `is` prefix (`isActive()`).  Readonly
// properties only offer a getter.  Static properties generate static
// methods.  If a getter or setter already exists, the corresponding action
// is suppressed.

class GenerateGetterSetterDemo
{
    private string $name;
    private bool $active;
    public readonly int $id;
    private static int $count;
    /** @var list<string> */
    public $tags;
}


// ── Generate Property Hooks (Code Action, PHP 8.4+) ────────────────────────
// Place the cursor on a property declaration below and trigger "Code Action"
// to see "Generate get hook", "Generate set hook", and "Generate get and set
// hooks".  The property declaration is rewritten to include hook blocks
// inline.  Readonly properties are skipped (PHP 8.4 forbids hooks on readonly
// properties).  Static properties are also skipped.  Interface
// properties generate abstract hook signatures without bodies.  Properties
// that already have one hook only offer the missing one.

class GeneratePropertyHooksDemo
{
    // Cursor here → all three hook actions offered
    public string $title;

    // Cursor here → no hook actions (readonly properties cannot have hooks)
    public readonly int $id;

    // Cursor here → no hook actions (static)
    public static int $counter;

    // Cursor here → only "Generate set hook" (get already exists)
    public string $label {
        get => $this->label;
    }

    // Default values are preserved when hooks are added
    public string $status = 'draft';
}


// ── Property-Level Narrowing ────────────────────────────────────────────────

class PropertyNarrowingDemo
{
    private Pen|Pencil $tool;

    /** @var Pen|Pencil|null */
    public $untyped;

    public function demo(): void
    {
        // instanceof narrows a property inside the then-body
        if ($this->tool instanceof Pen) {
            $this->tool->write();             // narrowed to Pen
        }

        // Negated instanceof + early return narrows after the guard
        if (!$this->tool instanceof Pencil) {
            return;
        }
        $this->tool->sketch();                // narrowed to Pencil

        // assert() narrows an untyped property
        assert($this->untyped instanceof Pen);
        $this->untyped->color();              // narrowed to Pen
    }
}


// ── Attribute Signature Help ────────────────────────────────────────────────

#[Attribute]
class DemoRoute
{
    public function __construct(
        public string $path,
        public string $method = 'GET',
    ) {}
}

class AttributeSigHelpDemo
{
    // Try: place cursor inside the attribute parens and trigger signature help.
    // Named parameter completion also works: type "method:" after the first arg.
    #[DemoRoute('/users', method: 'POST')]
    public function store(): void {}
}


// ── Pass-by-Reference Parameter Type ────────────────────────────────────────

class PassByReferenceDemo
{
    public function demo(): void
    {
        // When a function takes a typed &$var parameter, the variable
        // acquires that type after the call.
        initPen($pen);
        $pen->write();                    // $pen is now Pen

        // Static method calls with by-ref parameters:
        PenFactory::create($staticPen);
        $staticPen->write();              // $staticPen is now Pen

        // Constructor calls with by-ref parameters:
        new PenBuilder($ctorPen);
        $ctorPen->write();                // $ctorPen is now Pen

        // Instance method calls ($this->method) with by-ref parameters:
        $this->init($thisPen);
        $thisPen->write();                // $thisPen is now Pen
    }

    private function init(?Pen &$pen): void
    {
        $pen = new Pen();
    }
}


// ── Interface Template Inheritance ──────────────────────────────────────────

class InterfaceTemplateDemo
{
    public function demo(): void
    {
        // When a class implements an interface with @template + class-string<T>,
        // the implementing class inherits the template machinery.
        $locator = new ScaffoldingEntityLocator();
        $locator->find(Pen::class)->write();   // T resolves to Pen via class-string<T>
    }
}


// ── Function-level @template (collect) ──────────────────────────────────────

class CollectGenericDemo
{
    public function demo(): void
    {
        /** @var Pen[] $pens */
        $pens = [];

        // collect() uses function-level @template to carry element types
        // through to the returned FluentCollection.
        $collection = collect($pens);
        $collection->first()->write();    // TValue resolves to Pen

        // Inline chaining works too
        collect($pens)->first()->write(); // same resolution, no intermediate variable
    }
}


// ── Generic @phpstan-assert Narrowing ───────────────────────────────────────

class GenericAssertNarrowingDemo
{
    public function demo(object $obj): void
    {
        // @phpstan-assert with @template + class-string<T> resolves
        // the narrowed type from the call-site argument.
        ScaffoldingAssert::assertInstanceOf(Pen::class, $obj);
        $obj->write();                    // $obj narrowed to Pen
    }

    public function demoVariableClass(string $cls, ?Pen $node): void
    {
        // When the asserted class is a variable that cannot be resolved
        // to a concrete class, the assertion narrows to `object`
        // intersected with the prior type: `null` is dropped but the
        // subject keeps the type it already had, so member access still
        // resolves instead of unresolving the subject entirely.
        ScaffoldingAssert::assertInstanceOf($cls, $node);
        $node->write();                   // $node kept as Pen (null dropped)
    }
}


// ── @param-closure-this ─────────────────────────────────────────────────────

class ParamClosureThisDemo
{
    public function demo(): void
    {
        $router = new ScaffoldingClosureThisRouter();

        // @param-closure-this overrides $this inside the closure to
        // ScaffoldingClosureThisRoute instead of ParamClosureThisDemo.
        $router->group(function () {
            $this->middleware('auth');     // resolves Route::middleware()
            $this->prefix('/api');        // resolves Route::prefix()
        });

        // Chaining through the overridden $this
        $router->group(function () {
            $this->middleware('auth')->prefix('/v2');
        });

        // @param-closure-this with $this as the type (declares the
        // closure's $this is the method's declaring class).
        $router->extend('redis', function () {
            $this->getDefaultDriver();    // resolves Router::getDefaultDriver()
        });
    }
}


// ── Code Lens: prototype method annotations ─────────────────────────────────
// Open this class and look at the gutter above each method. PHPantom shows
// clickable annotations ("↑ ParentClass::method" or "◆ Interface::method")
// that navigate to the parent/interface declaration.
class CodeLensDemo extends ScaffoldingAbstractShape implements ScaffoldingDrawable
{
    // ↑ ScaffoldingAbstractShape::area  — click to jump to abstract declaration
    public function area(): float { return 3.14; }

    // ↑ ScaffoldingAbstractShape::perimeter
    protected function perimeter(): float { return 6.28; }

    // ◆ ScaffoldingDrawable::draw  — interface implementations use ◆
    public function draw(string $color, float $opacity = 1.0): void {}
}


// ── Inlay Hints ─────────────────────────────────────────────────────────────
// Enable inlay hints in your editor to see parameter names, by-reference
// indicators, and closure type hints. PHPantom shows:
//   - Parameter name hints: greet(/*name:*/ 'Alice', /*age:*/ 25)
//   - By-reference indicators: modify(/*&data:*/ $arr)
//   - Closure param types: $users->map(fn(/*User*/ $u) => $u->name)
//   - Closure return types: fn($u) /*: string*/ => $u->name
// Hints are suppressed when the argument already makes the parameter obvious
// (e.g. $name matches $name, or a property ->name matches $name).

class InlayHintsDemo
{
    public function demo(): void
    {
        // Parameter name hints appear before each argument:
        $user = createUser('Alice', 'test@example.com');          // name:, email:

        // By-reference parameters show & before the name:
        $arr = [1, 2, 3];
        $this->modify($arr, 'ascending');         // &data:, direction:

        // Hints are suppressed when variable name matches parameter:
        $needle = 'search term';
        $this->search($needle, 10);               // (no hint for $needle), limit:

        // Constructor calls also get hints:
        $recipe = new Recipe('Cake', [new Ingredient('flour', 2)]);  // name:, ingredients:

        // Static method calls:
        User::findByEmail('alice@example.com');    // email:

        // Chained method calls:
        $pen = Pen::make('blue');                  // color:
        $pen->rename('Sky Blue');                  // name:

        // ── Closure / arrow function hints ─────────────────────────
        // When a closure or arrow function is passed to a callable-typed
        // parameter, PHPantom infers types from the callable signature.
        // Untyped params show the inferred type before $var, and the
        // return type shows after the closing parenthesis.

        // Arrow function: "User " before $u, ": string" after parens.
        $names = $this->mapUsers(fn($u) => $u->name);

        // Long-form closure gets the same treatment:
        $upper = $this->mapUsers(function ($u) {
            return strtoupper($u->name);
        });

        // Partial typing: only the untyped $b gets a hint.
        $sum2 = $this->reduce(fn(int $a, $b) => $a + $b);

        // Already-typed parameters and return types get no hint:
        $emails = $this->mapUsers(fn(User $u): string => $u->email);

        // Standalone functions with callable params work too:
        $doubled = $this->transformItems([1, 2, 3], fn($x) => $x * 2);

        // Method call context — filter shows "Order " before $o, ": bool" after.
        $big = $this->filterOrders(fn($o) => $o->isAdmin);
    }

    /** @param array<int> &$data */
    public function modify(array &$data, string $direction): void {}

    public function search(string $needle, int $limit = 10): mixed { return null; }

    /**
     * @template T
     * @param array<T> $items
     * @param callable(T): T $fn
     * @return array<T>
     */
    public function transformItems(array $items, callable $fn): array { return $fn(); }

    /** @param \Closure(User): string $fn */
    public function mapUsers(\Closure $fn): array { return []; }

    /** @param callable(int, int): int $fn */
    public function reduce(callable $fn): int { return 0; }

    /** @param callable(User): bool $fn */
    public function filterOrders(callable $fn): array { return []; }
}


// ── Change Visibility ───────────────────────────────────────────────────────
// Place cursor on any member and trigger code actions (Ctrl+. / Cmd+.).
// PHPantom offers "Make protected", "Make private", etc.

class ChangeVisibilityDemo
{
    public string $title = '';
    protected int $count = 0;
    private bool $active = true;

    public function getTitle(): string { return $this->title; }
    protected function increment(): void { $this->count++; }
    private function toggle(): void { $this->active = !$this->active; }

    public const VERSION = 1;
    protected const LIMIT = 100;
    private const SECRET = 'shh';

    // Promoted constructor parameters also support visibility change:
    public function __construct(
        private string $name,
        protected int $age,
        public string $role = 'user',
    ) {}
}


// ── Update Docblock ─────────────────────────────────────────────────────────
// Place cursor on a method with a stale docblock and trigger code actions.
// PHPantom offers "Update docblock to match signature" when the @param
// tags are out of sync with the actual parameters.

class UpdateDocblockDemo
{
    /**
     * This docblock is out of date: $old was removed, $added is new,
     * and $renamed had its type changed from string to int.
     *
     * @param string $old This param was removed
     * @param string $renamed Wrong type, should be int
     * @return string Wrong return type, should be array
     */
    public function staleDocblock(int $renamed, bool $added): array
    {
        return [];
    }

    /**
     * Redundant @return void is removed when the signature already says void.
     *
     * @param string $name
     * @return void
     */
    public function redundantReturn(string $name): void {}

    /**
     * Refinement types in docblocks are preserved (not overwritten).
     *
     * @param non-empty-string $label A descriptive label
     * @param array<int, string> $tags Tag list
     */
    public function refinementsPreserved(string $label, array $tags): void {}
}


// ── Type Specificity in Virtual Property Merging ────────────────────────────

class TypeSpecificityDemo
{
    public function demo(): void
    {
        $cfg = new ScaffoldingAppConfig();

        // Hover $cfg->locale — should show string (from native type hint),
        // not mixed (from the trait's @property tag).
        $cfg->locale;

        // Hover $cfg->timezone — should show string (from native type hint),
        // not mixed (from the trait's @property tag).
        $cfg->timezone;

        // Hover $cfg->retries — should show int (from native type hint),
        // not mixed (from the trait's @property tag).
        $cfg->retries;
    }
}


// ── Mixin Generic Substitution ──────────────────────────────────────────────

class MixinGenericDemo
{
    public function demo(): void
    {
        $line = new ScaffoldingOrderLine();

        // @mixin Builder<TRelatedModel> on Relation resolves TModel → Product
        // through: BelongsTo @extends Relation<Product> → @mixin Builder<TRelatedModel>
        // → TRelatedModel=Product → Builder<Product> → firstOrFail(): TModel=Product
        $line->product()->firstOrFail()->getPrice();

        // Same resolution through find()
        $line->product()->find()->getSku();
    }
}


// ── Constant Type Inference ─────────────────────────────────────────────────
// Hover over $timeout, $name, $rate, $enabled, or $hosts to see the type
// inferred from the constant's initializer value.

class ConstantTypeDemo
{
    const TIMEOUT = 30;
    const NAME = 'app';
    const RATE = 3.14;
    const ENABLED = true;

    public function demo(): void
    {
        // Class constants without type hints — type inferred from value:
        $timeout = self::TIMEOUT;   // → int
        $name    = self::NAME;      // → string
        $rate    = self::RATE;      // → float
        $enabled = self::ENABLED;   // → bool

        // Global constants — type inferred from define()/const value:
        $hosts   = CT_ALLOWED_HOSTS;  // → array
        $version = CT_APP_VERSION;    // → string
    }
}


// ── Extract Function / Method (Code Action) ────────────────────────────────
// Select one or more complete statements inside a method body and trigger
// "Code Action" to see "Extract function" or "Extract method".
//
// Variables defined before the selection become parameters.  Variables
// written inside the selection and read afterwards become return values.
// When $this is used, the code is extracted as a private method.

class ExtractFunctionDemo
{
    private int $factor = 3;

    public function demo(): void
    {
        // Select these two lines and extract:
        // → creates a function with $x as return value (read after selection)
        $x = 10;
        $y = $x * 2;

        echo $x + $y;
    }

    public function methodExtraction(): void
    {
        // Select this line and extract:
        // → creates a private method (uses $this)
        $result = $this->factor * 42;

        echo $result;
    }

    public static function staticExtraction(): void
    {
        // Select these lines and extract:
        // → creates a private static method
        $a = 1;
        $b = 2;

        echo $a + $b;
    }
}


// ── Promote Constructor Parameter ───────────────────────────────────────────
// Place cursor on a constructor parameter (e.g. `string $name`) and trigger
// code actions to see "Promote to constructor property".  The action removes
// the property declaration, removes the `$this->name = $name;` assignment,
// and adds the visibility modifier directly on the parameter.

class PromoteConstructorParamDemo
{
    private string $name;
    protected int $age;
    private readonly string $email;

    public function __construct(string $name, int $age, string $email) {
        $this->name = $name;
        $this->age = $age;
        $this->email = $email;
    }
}

// ── Simplify Null Coalescing / Null-Safe ────────────────────────────────────
// Place your cursor on any ternary below and trigger code actions.
// PHPantom offers "Simplify to ??" or "Simplify to ?->" where applicable.

class SimplifyNullDemo
{
    public function demo(?Pen $pen, ?User $user): void
    {
        // ── isset → ?? ─────────────────────────────────────────────
        // Code action: "Simplify to ??"  →  $pen ?? makePen()
        $tool = isset($pen) ? $pen : makePen();

        // ── !== null → ?? ──────────────────────────────────────────
        // Code action: "Simplify to ??"  →  $pen ?? makePen()
        $tool2 = $pen !== null ? $pen : makePen();

        // ── === null (reversed) → ?? ───────────────────────────────
        // Code action: "Simplify to ??"  →  $user ?? createUser()
        $fallback = $user === null ? createUser() : $user;

        // ── !== null + method call → ?-> ───────────────────────────
        // Code action: "Simplify to ?->"  →  $pen?->color()
        $color = $pen !== null ? $pen->color() : null;

        // ── !== null + property access → ?-> ───────────────────────
        // Code action: "Simplify to ?->"  →  $user?->email
        $email = $user !== null ? $user->email : null;

        // ── === null + method (reversed) → ?-> ─────────────────────
        // Code action: "Simplify to ?->"  →  $pen?->label()
        $label = $pen === null ? null : $pen->label();

        // ── Compound subject → correct ?-> placement ───────────────
        // Code action: "Simplify to ?->"  →  $user->getProfile()?->getDisplayName()
        $profile = $user->getProfile();
        $name = $profile !== null ? $profile->getDisplayName() : null;
    }
}


// ── Attribute Completion ────────────────────────────────────────────────────
// Inside `#[…]`, completion only offers classes decorated with
// `#[\Attribute]`, filtered by the target of the declaration the
// attribute applies to.

class AttributeCompletionDemo
{
    public string $property;

    public function demo(): void
    {
        // Nothing to complete at runtime — this demo is about the
        // completion popup.  Open the class below and trigger
        // completion inside the `#[…]` brackets to see it in action.
    }
}



// ── Loop Array Build (variable-key assignment tracking) ─────────────────────

class LoopArrayBuildDemo
{
    /** @param list<Pen> $pens */
    public function demo(array $pens): void
    {
        // Variable-key assignment inside a loop: `$arr[$var] = $value`
        // PHPantom tracks the RHS type as the array's element type.
        $indexed = [];
        foreach ($pens as $i => $pen) {
            $key = $pen->color();
            $indexed[$key] = $pen;
        }

        // Foreach over the built array resolves element members
        foreach ($indexed as $item) {
            $item->write();               // Pen method via element type tracking
        }

        // Bracket access resolves element type
        $indexed['red']->color();         // Pen method

        // Null-coalescing with guard clause
        $found = $indexed['blue'] ?? null;
        if ($found === null) { return; }
        $found->write();                  // narrowed to Pen
    }
}

class ConditionalLoopShapeDemo
{
    /** @param list<Pen> $pens */
    public function demo(array $pens): void
    {
        // Array built with variable keys inside a loop where the assignment
        // is inside a conditional branch (if/else). The shape type from
        // the array literal is preserved through foreach iteration.
        $grouped = [];
        foreach ($pens as $pen) {
            $key = $pen->color();
            if (array_key_exists($key, $grouped)) {
                $grouped[$key]['count']++;
            } else {
                $grouped[$key] = [
                    'tool'  => $pen,
                    'count' => 1,
                ];
            }
        }

        // Foreach over the built array resolves shape keys
        foreach ($grouped as $entry) {
            $entry['tool']->write();      // Pen method via shape tracking
        }
    }
}


// ── Conditional Shape Key Completion ────────────────────────────────────────
// When an array shape gains a key inside an if-block, completion resolves
// through the union of shapes produced by branch merging.

class ConditionalShapeKeyDemo
{
    public function demo(?Pen $pen): void
    {
        // Base shape with a known key
        $options = [
            'name' => 'default',
        ];

        // Conditionally add a key with an object value
        if ($pen !== null) {
            $options['tool'] = $pen;
        }

        // After the if-block, $options is a union of shapes:
        //   array{name: string} | array{name: string, tool: Pen}
        // Completion on the conditionally-added key resolves to Pen.
        $options['tool']->write();        // Pen method via conditional shape union
    }
}


// ── Invalid Class-Like Kind Diagnostics ─────────────────────────────────────
// PHPantom flags class-like names used in positions where their kind is
// guaranteed to fail at runtime.  Open demo() and look for Error/Warning
// squiggles on the class names.

class InvalidClassKindDemo
{
    public function demo(): void
    {
        // Error: cannot instantiate abstract class
        $a = new ScaffoldingAbstractShape();

        // Error: cannot instantiate enum
        $b = new Status();

        // Warning: instanceof with a trait always evaluates to false
        $x = new Pen('test');
        $result = $x instanceof JsonSerializer;

        // Warning: trait in a type hint will always fail type checking
        $this->acceptTrait(new Pen('test'));
    }

    private function acceptTrait(JsonSerializer $x): JsonSerializer
    {
        return $x;
    }

    // These also produce diagnostics but would crash at class-load time,
    // so they are commented out.  See the AGENTS.md hoisting pitfall note.
}


// ── Untyped Property Inference ──────────────────────────────────────────────
// Properties without type declarations have their types inferred from
// constructor assignments (`$this->prop = new Foo()`) and promoted
// parameter defaults (`private $prop = new Foo()`). Trigger completion
// after `->` on the property to see methods from the inferred type.

class UntypedPropertyInferenceDemo
{
    private $repository;
    private $logger;

    public function __construct(
        private $defaultRepo = new ScaffoldingUntypedRepo(),
    ) {
        $this->repository = new ScaffoldingUntypedRepo();
        $this->logger = new ScaffoldingUntypedLogger();
    }

    public function demo(): void
    {
        // Constructor body assignment: $this->repository = new ScaffoldingUntypedRepo()
        $this->repository->findById(1);       // resolves ScaffoldingUntypedRepo::findById()

        // Constructor body assignment: $this->logger = new ScaffoldingUntypedLogger()
        $this->logger->info('hello');         // resolves ScaffoldingUntypedLogger::info()

        // Promoted parameter default: private $defaultRepo = new ScaffoldingUntypedRepo()
        $this->defaultRepo->findById(42);     // resolves ScaffoldingUntypedRepo::findById()
    }
}


// ── Deep Variable Chain ─────────────────────────────────────────────────────
// The variable resolver walks function bodies top-to-bottom in a single pass.
// Assignment chains of any depth resolve without recursion or depth limits.
// Place the cursor after `->` on any variable below to see completions from
// the correct class, regardless of how many intermediate assignments there are.

class DeepVariableChainDemo
{
    public function demo(): void
    {
        // 5-level chain: each variable is assigned from a method/property on the previous.
        $brush = new Brush();
        $canvas = $brush->getCanvas();
        $easel = $canvas->easel;
        $material = $easel->material;         // string from Easel::$material
        $back = $canvas->getBrush();
        $back->stroke();                      // Brush::stroke() — full round-trip

        // Reassignment chains: the resolver picks the most recent assignment.
        $tool = new Pen();
        $tool->write();                       // Pen::write()
        $tool = new Pencil();
        $tool->sketch();                      // Pencil::sketch() — Pen::write() is gone
        $tool = new Marker();
        $tool->highlight();                   // Marker::highlight()
    }
}


// ── Closure Scope Inference ─────────────────────────────────────────────────
// Closures capture variables from the enclosing scope via `use()`. Arrow
// functions inherit the enclosing scope automatically. Untyped closure
// parameters are inferred from the callable signature of the enclosing call.

class ClosureScopeInferenceDemo
{
    /** @param list<Pen> $pens */
    public function demo(array $pens): void
    {
        // Closure captures $pens via use() and iterates over it.
        $worker = function () use ($pens): void {
            foreach ($pens as $pen) {
                $pen->write();                // Pen from captured $pens
            }
        };

        // Arrow function inherits enclosing scope automatically.
        $brush = new Brush();
        $sized = fn() => $brush->setSize('large');

        // Variables survive past closure arguments in chained calls.
        $product = new Pen();
        $items = [1, 2, 3];
        array_map(function (int $i) { return $i * 2; }, $items);
        $product->write();                    // Pen — not lost after the closure
    }
}

// ── Body Return Type Inference ──────────────────────────────────────────────
// When a method has no declared return type and no @return docblock,
// PHPantom infers the type by scanning the method body for return statements.

class BodyReturnTypeDemo
{
    public function demo(): void
    {
        $factory = new ScaffoldingUntypedFactory();

        // Single return: `return new Pen()` → Pen
        $pen = $factory->createPen();
        $pen->write();

        // Multiple returns: union of `new Pen()` and `new Pencil()`
        $tool = $factory->createTool(true);
        $tool->write();                           // shared by Pen (also Pencil via sketch)

        // No return statements → void (no completions)
        $factory->setup();

        $pencils = $factory->getPencils();
        foreach ($pencils as $pencil) {
            $pencil->sketch();
        }
    }
}

// ── Global Keyword ─────────────────────────────────────────────────────────

$globalPen = new Pen();

function globalKeywordDemo(): void {
    global $globalPen;
    $globalPen->write();                  // Pen — resolved from top-level scope via `global`
}

// ── Method-Tag Template ─────────────────────────────────────────────────────

class MethodTagTemplateDemo
{
    public function demo(): void
    {
        // @method tags with <T of Bound> template params resolve at call sites.
        $registry = new ScaffoldingMethodTagTemplate();

        // TVal inferred from argument type
        $pen = new Pen('demo');
        $result = $registry->get($pen);
        $result->write();                 // TVal = Pen

        // Inline chain
        $registry->get(new Pencil())->sketch(); // TVal = Pencil
    }
}

/**
 * Convert to arrow function — place cursor on a single-expression closure
 * and trigger code actions to see "Convert to arrow function".
 */
class ConvertToArrowFunctionDemo
{
    public function demo(): void
    {
        // Try: place cursor on `function` and use code action
        $double = function(int $x): int { return $x * 2; };

        // Static closure with use clause (by-value)
        $base = 10;
        $add = static function(int $x) use ($base) { return $x + $base; };

        // Passes as callback — trigger inside the closure
        $result = array_map(function(string $s) { return strtoupper($s); }, ['a', 'b']);
    }
}

class ConvertToClosureDemo
{
    public function demo(): void
    {
        // Try: place cursor on `fn` and use code action "Convert to closure"
        $double = fn(int $x): int => $x * 2;

        // Arrow with captured outer variable — converted closure gets use()
        $base = 10;
        $add = fn(int $x) => $x + $base;

        // Static arrow function
        $staticFn = static fn(string $s): string => strtoupper($s);

        // Arrow as callback — trigger inside the arrow function
        $result = array_map(fn(string $s) => strtoupper($s), ['a', 'b']);

        // Multiple captured variables
        $prefix = 'hello';
        $suffix = 'world';
        $greet = fn(string $sep) => $prefix . $sep . $suffix;
    }
}

// ── @phpstan-require-extends: base members on $this in a trait ───────────────

/**
 * A trait annotated with `@phpstan-require-extends` guarantees that every
 * class using it extends the named base class, so `$this` inside the trait
 * can access that base class's members even though the trait analyzed
 * standalone does not declare them.
 *
 * @phpstan-require-extends RequireExtendsTestCase
 */
trait MocksServiceDemo
{
    public function mockPath(): string
    {
        $mock = $this->makeMock();                // RequireExtendsTestCase::makeMock() → Mock
        return $mock->path();                     // Mock::path() → string
    }
}

// ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
// ┃  SCAFFOLDING — Supporting definitions below this line.              ┃

// ── @phpstan-require-extends scaffolding ────────────────────────────────────

class Mock
{
    public function path(): string { return '/tmp/mock'; }
}

class RequireExtendsTestCase
{
    public function makeMock(): Mock { return new Mock(); }
}

final class RequireExtendsConsumer extends RequireExtendsTestCase
{
    use MocksServiceDemo;
}

// ── SPL wrapper-iterator scaffolding ───────────────────────────────────────────

/**
 * A FilterIterator subclass with a three-argument generic annotation
 * (`<TKey, TValue, TIterator>`). The iterated value type is the middle
 * argument.
 *
 * @extends \FilterIterator<int, \SplFileInfo, \Iterator<int, \SplFileInfo>>
 */
class PhpFileFilter extends \FilterIterator
{
    public function accept(): bool
    {
        return $this->current() instanceof \SplFileInfo;
    }
}

// ── Member-existence narrowing scaffolding ─────────────────────────────────────

// Response object whose extra fields are populated dynamically at runtime, so
// they are not declared statically. `property_exists()` guards prove them.
#[\AllowDynamicProperties]
class ApiResponse
{
    public int $status = 0;
}

// Handler whose `customHook()` is not declared — `method_exists()` guards prove
// it. Deliberately has no `__call`, so only the guard makes the call resolve.
class DynamicHandler
{
    public function run(): void {}
}

// ── Method-Tag Template scaffolding ────────────────────────────────────────────

/**
 * @method TVal get<TVal of mixed>(TVal $default)
 */
class ScaffoldingMethodTagTemplate
{
    /** @return mixed */
    public function __call(string $name, array $args): mixed { return $args[0] ?? null; }
}

// ── Template-param @mixin scaffolding ─────────────────────────────────────────
interface ScaffoldingAstNodeInterface {
    public function getStartColumn(): int;
    public function getEndColumn(): int;
}

/**
 * @template-covariant TNode of ScaffoldingAstNodeInterface
 * @mixin TNode
 */
abstract class ScaffoldingAbstractAstNode {
    /** @return string */
    public function getMetric(): string { return ''; }
    /** @return mixed */
    public function __call(string $name, array $arguments): mixed {
        return match ($name) {
            'getStartColumn', 'getEndColumn', 'getParameterCount' => 0,
            default => null,
        };
    }
}

/**
 * @extends ScaffoldingAbstractAstNode<ScaffoldingAstNodeInterface>
 */
class ScaffoldingConcreteAstNode extends ScaffoldingAbstractAstNode {}

// A subclass tightens the template bound to a narrower interface that adds
// `getParameterCount()`.  The `@mixin TNode` still lives on the base
// `ScaffoldingAbstractAstNode` (bound to the looser interface), so resolving
// the tighter member exercises picking the most specific bound in the chain.
interface ScaffoldingCallableAstNodeInterface extends ScaffoldingAstNodeInterface {
    public function getParameterCount(): int;
}

/**
 * @template-covariant TNode of ScaffoldingCallableAstNodeInterface
 * @extends ScaffoldingAbstractAstNode<TNode>
 */
abstract class ScaffoldingAbstractCallableAstNode extends ScaffoldingAbstractAstNode {}

/**
 * @extends ScaffoldingAbstractCallableAstNode<ScaffoldingCallableAstNodeInterface>
 */
class ScaffoldingConcreteCallableAstNode extends ScaffoldingAbstractCallableAstNode {}

// ── Pseudo-type class-name collision scaffolding ─────────────────────────────
// `Number` collides with the `number` PHPDoc pseudo-type but is a real class.
class Number {
    public function __construct(public string $value) {}
    public function scaled(int $factor): Number {
        return new Number((string) ((int) $this->value * $factor));
    }
}

function scaleNumber(Number $n): Number {
    return $n->scaled(10);
}

// ── class-string<T> instantiation scaffolding ───────────────────────────────
class ScaffoldingClassStringFactory {
    /**
     * @template T of object
     * @param class-string<T> $class
     * @return T
     */
    public static function create(string $class): object { return new $class(); }
}

// ── Attribute Completion scaffolding ────────────────────────────────────────
#[\Attribute(\Attribute::TARGET_CLASS)]
class ClassOnlyAttr {}

#[\Attribute(\Attribute::TARGET_METHOD)]
class MethodOnlyAttr {}

#[\Attribute(\Attribute::TARGET_PROPERTY)]
class PropertyOnlyAttr {}

#[\Attribute(\Attribute::TARGET_CLASS | \Attribute::TARGET_METHOD)]
class ClassOrMethodAttr {}

#[\Attribute]
class AnyTargetAttr {}

// ── Constant Type Demo scaffolding ──────────────────────────────────────────
define('CT_ALLOWED_HOSTS', ['localhost', '127.0.0.1']);
const CT_APP_VERSION = '2.0.0';

// StaticPropHolder — used by MixedAccessorDemo
class StaticPropHolder
{
    public static string $shared = 'hello';

    /** @var self */
    public self $holder;
}

// TreeMapperImpl — used by ConditionalReturnDemo (literal string conditional)
class TreeMapperImpl
{
    /**
     * @return ($signature is "foo" ? Pen : Marker)
     */
    public function map(string $signature, mixed $source): Pen|Marker
    {
        return new Pen();
    }
}

// ┃  Everything below exists to support the demos above.               ┃
// ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
//
// Keep shared classes NARROW (2-4 members). The whole point of the demos
// is that a human can glance at the completion list and immediately tell
// whether the right type resolved. A 15-member class defeats that because
// the expected item could be buried on page two.
//
// If a demo needs a richer object, create a NEW class in a demo-specific
// section instead of expanding a shared one. Every member you add to a
// shared class leaks into every demo that uses it.
//
// RUNTIME ASSERTIONS: When adding a new demo, add matching assert() calls
// to runDemoAssertions() at the bottom of the Demo namespace. This catches
// cases where our scaffolding stubs don't actually return what their
// docblocks claim. Run: php -d zend.assertions=1 examples/demo.php
//
// HOISTING PITFALL: Do NOT add __toString() to any class that is
// forward-referenced via `extends` or `implements`. PHP implicitly adds
// `implements \Stringable`, which prevents class hoisting. This is a
// known PHP limitation (php-src#7873), not a bug that will be fixed.
// The same applies to `interface Foo extends \Stringable`.


// ── Untyped Property Inference Scaffolding ──────────────────────────────────

class ScaffoldingUntypedRepo
{
    public function findById(int $id): Pen { return new Pen('found'); }
    public function save(Pen $pen): void {}
}

class ScaffoldingUntypedLogger
{
    public function info(string $msg): void {}
    public function error(string $msg): void {}
}

// ── Demo-Specific Scaffolding ───────────────────────────────────────────────

// ── Body Return Type Inference scaffolding ──────────────────────────────────
class ScaffoldingUntypedFactory
{
    public function createPen() { return new Pen(); }

    public function createTool(bool $flag)
    {
        if ($flag) {
            return new Pen();
        }
        return new Pencil();
    }

    public function setup() { echo 'initializing'; }

    public function getPencils()
    {
        return [new Pencil()];
    }
}

// ── Inherited Docblock Scaffolding ──────────────────────────────────────────

interface ScaffoldingPenHolderInterface
{
    /** @return list<Pen> */
    public function getPens(): array;

    /** @param list<Pen> $pens */
    public function accept(array $pens): void;
}

class ScaffoldingConcreteHolder implements ScaffoldingPenHolderInterface
{
    public function getPens(): array { return [new Pen()]; }
    public function accept(array $pens): void {}
}

class ScaffoldingPenBox implements ScaffoldingPenHolderInterface
{
    public function getPens(): array { return [new Pen()]; }
    public function accept(array $items): void {}  // renamed param
}

class ScaffoldingBasePenHolder
{
    /** @return list<Pen> */
    public function getPens(): array { return [new Pen()]; }
}

class ScaffoldingChildHolder extends ScaffoldingBasePenHolder
{
    public function getPens(): array { return [new Pen()]; }
}

class ScaffoldingMidHolder extends ScaffoldingBasePenHolder
{
    public function getPens(): array { return [new Pen()]; }
}

class ScaffoldingDeepChild extends ScaffoldingMidHolder
{
    public function getPens(): array { return [new Pen()]; }
}

class ScaffoldingAnimalStore
{
    /** @return list<Pen> */
    public function getAnimals(): array { return [new Pen()]; }
}

class ScaffoldingCatStore extends ScaffoldingAnimalStore
{
    /** @return list<Pencil> */
    public function getAnimals(): array { return [new Pencil()]; }
}


class ScaffoldingMotor
{
    public function start(): void {}
}

class ScaffoldingSedan extends ScaffoldingMotor
{
    public function cruise(): void {}
}

abstract class ScaffoldingAbstractShape
{
    abstract public function area(): float;
    abstract protected function perimeter(): float;
}

interface ScaffoldingDrawable
{
    public function draw(string $color, float $opacity = 1.0): void;
}

class ScaffoldingSignatureHelp
{
    /**
     * Paginate a result set.
     *
     * @param int $page Current page number.
     * @param int $limit Max items per page.
     * @return array The paginated slice of results.
     */
    public function paginate(int $page = 1, int $limit = 25): array { return []; }

    /**
     * Search for items matching a query.
     *
     * @param non-empty-string $query The search keywords.
     * @param positive-int $page Page number to return.
     * @param int $perPage Results per page.
     * @return list<array{id: int, title: string}> Matching items.
     */
    public function search(string $query, int $page = 1, int $perPage = 20): array { return []; }
}

class ScaffoldingDeprecation
{
    /**
     * @deprecated Use sendAsync() instead.
     * @see ScaffoldingDeprecation::sendAsync()
     */
    public function sendLegacy(): void {}

    /**
     * @deprecated
     * @see ScaffoldingDeprecation::sendAsync()
     */
    public function oldProcess(): void {}

    public function sendAsync(): void {}

    /**
     * @deprecated Use isDebug() instead.
     * @see ScaffoldingDeprecation::sendAsync()
     */
    public bool $debugMode = false;

    /**
     * @deprecated Use MAX_LIMIT instead.
     * @see ScaffoldingDeprecation::MAX_LIMIT
     */
    const OLD_LIMIT = 100;

    const MAX_LIMIT = 500;

    // JetBrains stubs style
    #[\JetBrains\PhpStorm\Deprecated(reason: "Use modernMethod() instead", since: "8.1")]
    public function attrDeprecatedMethod(): void {}

    // Native PHP 8.4 style (\Deprecated)
    #[\Deprecated(message: "Use nativeModern() instead", since: "8.4")]
    public function nativeDeprecatedMethod(): void {}

    #[\Deprecated]
    public function attrBareMethod(): void {}

    #[\Deprecated("Use positionalModern() instead")]
    public function attrPositionalMethod(): void {}

    #[\JetBrains\PhpStorm\Deprecated(reason: "The property is deprecated", since: "8.4")]
    public string $attrProp = '';

    #[\Deprecated(reason: "Use NEW_SETTING instead")]
    const ATTR_OLD = 0;

    /**
     * @deprecated Docblock message wins.
     */
    #[\Deprecated(reason: "Attribute message loses")]
    public function bothDocAndAttr(): void {}

    #[\Deprecated(replacement: "%class%->setTimezone(%parametersList%)", since: "5.5")]
    public function legacySetTimezone(string $tz): void {}

    public function setTimezone(string $tz): void {}
}

/**
 * @property mixed $locale
 * @property mixed $timezone
 * @property mixed $retries
 */
trait ScaffoldingMixedDefaults {}

class ScaffoldingAppConfig
{
    use ScaffoldingMixedDefaults;

    public string $locale = 'en';
    public string $timezone = 'UTC';
    public int $retries = 3;
}

/**
 * @property string $gorilla
 * @method bool hyena(string $x)
 */
class Zoo extends ZooBase implements ZooContract
{
    use ZooTraitA;
    use ZooTraitB;

    public string $baboon = '';
    protected string $keeper = 'hidden';      // trip wire — must NOT appear on $zoo->
    private string $ceo = 'invisible';        // trip wire — must NOT appear on $zoo->

    public function aardvark(): void {}
    private function nocturnal(): void {}     // trip wire — must NOT appear on $zoo->

    public function __construct(
        public int $buffalo = 0,
    ) {
        parent::__construct();
    }

    public function __get(string $name): mixed
    {
        return match ($name) {
            'gorilla' => 'gorilla-value',   // @property string $gorilla
            'iguana'  => 'iguana-value',     // @property-read string $iguana (ZooContract)
            default   => null,
        };
    }

    public function __call(string $name, array $args): mixed
    {
        return match ($name) {
            'hyena'  => true,               // @method bool hyena(string $x)
            'jaguar' => 'jaguar-value',     // @method string jaguar() (ZooContract)
            default  => null,
        };
    }
}

abstract class ZooBase
{
    public function __construct(
        public readonly string $cheetah = '',
    ) {}

    public function falcon(): string { return ''; }
}

trait ZooTraitA
{
    public function dingo(): void {}
}

trait ZooTraitB
{
    public function elephant(string $value): string { return $value; }
}

trait MakesPageAssertions
{
    /** Fluent assertion with no declared return type — body returns $this. */
    public function assertSee(string $value)
    {
        $seen = $value !== '';
        return $this;
    }
}

class TestablePage
{
    use MakesPageAssertions;

    public int $status = 200;

    public function refresh(): static
    {
        return $this;
    }
}

/**
 * @property-read string $iguana
 * @method string jaguar()
 */
interface ZooContract {}

class ScaffoldingChainingDemo
{
    public Brush $brush;
    public Canvas $canvas;

    public function __construct()
    {
        $this->brush = new Brush();
        $this->canvas = new Canvas();
    }
}

class ScaffoldingExpressionType
{
    public ?Response $backup;
    public Response $primary;

    public function __construct()
    {
        $this->backup = new Response(500, 'Backup');
        $this->primary = new Response(200, 'OK');
    }
}

// ScaffoldingGenericShape — used by GenericShapeDemo
/**
 * @template T
 */
class ScaffoldingGenericShapeBase
{
    /** @return array{data: T, items: list<T>} */
    public function getResult(): array { return []; }
}

/**
 * @extends ScaffoldingGenericShapeBase<Gift>
 */
class ScaffoldingGenericShape extends ScaffoldingGenericShapeBase {}

class ScaffoldingCollectionForeach
{
    public PenCollection $pens;

    public function allPens(): PenCollection
    {
        return new PenCollection();
    }
}

class ScaffoldingGenericContext
{
    /** @var Box<Gift> */
    public $chest;

    public function __construct() { $this->chest = new Box(new Gift()); }

    /** @return TypedCollection<int, Gift> */
    public function display(): TypedCollection { return new TypedCollection([new Gift()]); }
}

class ScaffoldingIteration
{
    /** @var list<Pen> */
    public array $batch;

    /** @return list<Pen> */
    public function allPens(): array { return []; }

    /** @return array<Pen, Pencil> */
    public function crossRef(): array { return []; }
}

class ScaffoldingArrayFunc
{
    /** @var list<Pen> */
    public array $members;

    /** @return list<Pen> */
    public function roster(): array { return []; }
}

class ScaffoldingException
{
    protected function lookup(int $id): ?array { return null; }
    protected function riskyOperation(): void {}

    /** @throws AuthorizationException */
    protected function throwsException(): void { throw new AuthorizationException('forbidden'); }
}

class ScaffoldingClosureParamInference
{
    /** @var FluentCollection<int, Pen> */
    public FluentCollection $items;

    public function __construct() { $this->items = new FluentCollection([new Pen('red'), new Pen('blue')]); }
}

class ScaffoldingEventBus
{
    /**
     * @template T
     * @param Closure(T): void $callback
     * @return T
     */
    public function listen(Closure $callback): mixed
    {
        $params = (new \ReflectionFunction($callback))->getParameters();
        $type = $params[0]->getType();
        $class = $type instanceof \ReflectionNamedType ? $type->getName() : 'stdClass';
        return (new \ReflectionClass($class))->newInstanceWithoutConstructor();
    }
}

class ScaffoldingBatchProcessor
{
    /**
     * @template T
     * @param Closure(int, T): void $handler
     * @return T
     */
    public function process(Closure $handler): mixed
    {
        $params = (new \ReflectionFunction($handler))->getParameters();
        $type = $params[1]->getType();
        $class = $type instanceof \ReflectionNamedType ? $type->getName() : 'stdClass';
        return (new \ReflectionClass($class))->newInstanceWithoutConstructor();
    }
}

class ScaffoldingTemplateCallableHolder
{
    /** @var array<int, Pen> */
    public array $tools = [];
}

/**
 * @template TValue
 */
class ScaffoldingReducible
{
    /**
     * @template TReduceInitial
     * @template TReduceReturnType
     *
     * @param callable(TReduceInitial|TReduceReturnType, TValue): TReduceReturnType $callback
     * @param TReduceInitial $initial
     * @return TReduceReturnType
     */
    public function reduce(callable $callback, mixed $initial): mixed
    {
        return $initial;
    }
}

/**
 * Cache-like helper whose `@template T` is bound from the callback's
 * return type. Mirrors Laravel's `Cache::remember()` so an unannotated
 * `fn() => new Pen()` callback resolves the result to `Pen`.
 */
class ScaffoldingClosureCache
{
    /**
     * @template T
     *
     * @param \Closure(): T $callback
     * @return T
     */
    public function remember(string $key, \Closure $callback): mixed
    {
        return $callback();
    }
}

class ScaffoldingPipeline
{
    /**
     * @param callable($this, mixed): $this $callback
     * @return $this
     */
    public function when(bool $condition, callable $callback): static { return $this; }

    /**
     * @param callable($this): void $callback
     * @return $this
     */
    public function tap(callable $callback): static { return $this; }

    public function send(mixed $data): static { return $this; }
    public function through(array $pipes): static { return $this; }
}

// ScaffoldingClosureThisRoute / ScaffoldingClosureThisRouter — used by ParamClosureThisDemo
class ScaffoldingClosureThisRoute
{
    public function middleware(string $m): self { return $this; }
    public function prefix(string $p): self { return $this; }
}

class ScaffoldingClosureThisRouter
{
    public function getDefaultDriver(): string { return ''; }

    /**
     * @param-closure-this ScaffoldingClosureThisRoute $callback
     */
    public function group(\Closure $callback): void {}

    /**
     * @param string $driver
     * @param \Closure $callback
     * @param-closure-this $this $callback
     * @return $this
     */
    public function extend(string $driver, \Closure $callback): self { return $this; }
}

class ScaffoldingFirstClassCallable
{
    public function dispatch(): Pen
    {
        return new Pen();
    }
}

class ScaffoldingArrayAccess
{
    /** @return Pen[] */
    public function fetchAll(): array { return []; }
}

class ScaffoldingPenArrayAccess implements \ArrayAccess
{
    /** @var Pen[] */
    private array $items = [];

    public function offsetExists(mixed $offset): bool { return isset($this->items[$offset]); }
    public function offsetGet(mixed $offset): Pen { return $this->items[$offset] ?? new Pen(); }
    public function offsetSet(mixed $offset, mixed $value): void { $this->items[$offset] = $value; }
    public function offsetUnset(mixed $offset): void { unset($this->items[$offset]); }
}

/**
 * @template T of Pen
 * @implements \ArrayAccess<int, T>
 */
class ScaffoldingGenericArrayAccess implements \ArrayAccess
{
    /** @param T[] $items */
    public function __construct(private array $items) {}

    public function offsetExists(mixed $offset): bool { return isset($this->items[$offset]); }
    /** @return T */
    public function offsetGet(mixed $offset) { return $this->items[$offset]; }
    public function offsetSet(mixed $offset, mixed $value): void { $this->items[$offset] = $value; }
    public function offsetUnset(mixed $offset): void { unset($this->items[$offset]); }
}

class ScaffoldingFormatter
{
    public function __invoke(): Pen { return new Pen(); }
}

class ScaffoldingPenFactory
{
    public function __invoke(): Pen { return new Pen(); }
}

class ScaffoldingPenFetcher
{
    /** @return Pen[] */
    public function __invoke(): array { return []; }
}


// ── AST Node (template bounds demo) ────────────────────────────────────────

class AstNode
{
    /** @return AstNode|null */
    public function getParent(): ?AstNode { return null; }

    /** @return AstNode[] */
    public function getChildren(): array { return []; }

    public function getType(): string { return ''; }
}

// ── ObjectMapper (method-level @template demo) ──────────────────────────────

class ObjectMapper
{
    /**
     * @template T
     * @param T $item
     * @return TypedCollection<int, T>
     */
    public function wrap(object $item): TypedCollection
    {
        /** @var TypedCollection<int, T> */
        return new TypedCollection([$item]);
    }

    /**
     * @template T
     * @param T $item
     * @return T
     */
    public function identity(mixed $item): mixed
    {
        return $item;
    }

    /**
     * An identity generic whose *constraint* is an array type: `T` is
     * never bound from an argument at a call site, only from its
     * declared bound.  Inside the method body, `$pens` (typed `T`)
     * must resolve to that bound so array-element functions like
     * `end()` can find the element's class.
     *
     * @template T of Pen[]
     * @param T $pens
     * @return T
     */
    public function peekLast(array $pens): array
    {
        end($pens)->write();      // T resolves to its bound (Pen[]) inside the body
        return $pens;
    }
}


// ─── Interfaces ─────────────────────────────────────────────────────────────

/**
 * @method string render()
 * @property-read string $output
 */
interface Renderable
{
    public function format(string $template): string;
}

// ─── Traits ─────────────────────────────────────────────────────────────────

trait JsonSerializer {
    public function serialize(): string { return '{}'; }
    public function toJson(): string { return $this->serialize(); }
}

trait XmlSerializer {
    public function serialize(): string { return '<xml/>'; }
    public function toXml(): string { return $this->serialize(); }
}

trait HasTimestamps
{
    protected ?string $createdAt = null;

    public function getCreatedAt(): ?string
    {
        return $this->createdAt;
    }

    public function setCreatedAt(string $date): static
    {
        $this->createdAt = $date;
        return $this;
    }
}

trait HasSlug
{
    public function generateSlug(string $value): string
    {
        return strtolower(str_replace(' ', '-', $value));
    }
}

/**
 * @template TFactory
 */
trait HasFactory
{
    /** @return TFactory */
    public static function factory() {}
}

/**
 * @template TKey
 * @template TValue
 */
trait Indexable
{
    /** @return TValue */
    public function get() {}

    /** @return TKey */
    public function key() {}
}

// ─── Enums ──────────────────────────────────────────────────────────────────

enum Status: string
{
    case Active = 'active';
    case Inactive = 'inactive';
    case Pending = 'pending';

    public function label(): string
    {
        return match ($this) {
            self::Active   => 'Active',
            self::Inactive => 'Inactive',
            self::Pending  => 'Pending',
        };
    }

    public function isActive(): bool
    {
        return $this === self::Active;
    }

    /** Returns the raw backing value of the Active case. */
    public static function defaultValue(): string
    {
        return self::Active->value;  // self::CaseName->value resolved
    }
}

enum Priority: int
{
    case Low = 1;
    case Medium = 2;
    case High = 3;
}

enum Mode
{
    case Automatic;
    case Manual;
}

// ─── Builder (@mixin target) ────────────────────────────────────────────────

class Builder
{
    /** @return static */
    public static function query(): self
    {
        return new static();
    }

    public function where(string $col, mixed $val): self
    {
        return $this;
    }
}

// ─── Abstract Base Class ────────────────────────────────────────────────────

/**
 * @property string $magicName
 * @method static static create(array $attributes)
 * @mixin Builder
 */
abstract class Model
{
    protected int $id;

    public const string CONNECTION = 'default';
    protected const int PER_PAGE = 15;

    public function __construct(
        protected string $name = '',
        public readonly string $uuid = '',
    ) {
        $this->id = rand(1, 99999);
    }

    public function getId(): int
    {
        return $this->id;
    }

    public function getName(): string
    {
        return $this->name;
    }

    /** @return static */
    public function setName(string $name): static
    {
        $this->name = $name;
        return $this;
    }

    /** @deprecated */
    public static function find(int $id): ?static
    {
        return null;
    }

    /** @return static */
    public static function make(string $name = ''): static
    {
        return new static($name, '');
    }

    abstract public function toArray(): array;
}


// ─── Concrete Classes ───────────────────────────────────────────────────────

/**
 * @property string $displayName
 * @property-read bool $isAdmin
 * @method bool hasPermission(string $permission)
 */
class User extends Model implements Renderable
{
    use HasTimestamps;
    use HasSlug;

    public string $email;
    protected Status $status;
    private array $roles = [];
    public static string $defaultRole = 'user';
    public const string TYPE_ADMIN = 'admin';
    public const string TYPE_USER = 'user';

    public function __construct(
        string $name,
        string $email,
        private readonly string $password = '',
        public int $age = 0,
    ) {
        parent::__construct($name);
        $this->email = $email;
        $this->status = Status::Active;
    }

    public function getEmail(): string
    {
        return $this->email;
    }

    public function getStatus(): Status
    {
        return $this->status;
    }

    public function setStatus(Status $status): self
    {
        $this->status = $status;
        return $this;
    }

    public function addRoles(string ...$roles): void
    {
        $this->roles = array_merge($this->roles, $roles);
    }

    public function getRoles(): array
    {
        return $this->roles;
    }

    public function getProfile(): UserProfile
    {
        return new UserProfile($this);
    }

    public function toArray(): array
    {
        return [
            'id' => $this->getId(),
            'name' => $this->getName(),
            'email' => $this->email,
            'status' => $this->status->value,
        ];
    }

    public function format(string $template): string
    {
        return str_replace('{name}', $this->getName(), $template);
    }

    public static function findByEmail(string $email): ?self
    {
        return null;
    }

    protected function hashPassword(string $raw): string
    {
        return password_hash($raw, PASSWORD_BCRYPT);
    }

    private function secretInternalMethod(): void {}
}

class UserProfile
{
    public string $bio = '';

    public function __construct(private User $user) {}

    public function getUser(): User
    {
        return $this->user;
    }

    public function setBio(string $bio): self
    {
        $this->bio = $bio;
        return $this;
    }

    public function getDisplayName(): string
    {
        return $this->user->getName() . ' (' . $this->user->getEmail() . ')';
    }
}

final class AdminUser extends User
{
    /** @var string[] */
    private array $permissions = [];

    public function __construct(string $name, string $email)
    {
        parent::__construct($name, $email);
    }

    public function toArray(): array
    {
        $base = parent::toArray();
        $base['connection'] = parent::CONNECTION;
        $base['permissions'] = $this->permissions;
        return $base;
    }

    public function grantPermission(string $permission): void
    {
        $this->permissions[] = $permission;
    }
}

class Response
{
    public function __construct(
        private string|int $statusCode,
        private string|array|null $body = null,
    ) {}

    public function getStatusCode(): string|int
    {
        return $this->statusCode;
    }

    public function getBody(): string|array|null
    {
        return $this->body;
    }

    public function isSuccess(): bool
    {
        return $this->statusCode >= 200 && $this->statusCode < 300;
    }
}

// ─── Generics (@template / @extends) ───────────────────────────────────────

/**
 * @template T
 */
class Repository
{
    /** @var T|null */
    protected $cached = null;

    /** @return T */
    public function find(int $id)
    {
        return $this->cached;
    }

    /** @return T|null */
    public function findOrNull(int $id)
    {
        return $this->cached;
    }

    /** @return T */
    public function first()
    {
        return $this->cached;
    }
}

/** @extends Repository<Pen> */
class PenRepository extends Repository {}

class CachingPenRepository extends PenRepository
{
    public function clearCache(): void {}
}

// ─── @implements Generic Resolution ─────────────────────────────────────────

/**
 * @template TEntity
 */
interface Storage
{
    /** @return TEntity */
    public function find(int $id);

    /** @return TEntity[] */
    public function findAll();
}

/** @implements Storage<Pen> */
class PenStorage implements Storage
{
    public function find(int $id) { return new Pen(); }
    public function findAll() { return [new Pen()]; }
}

/** @template-implements Storage<Pen> */
class PenCatalog implements Storage
{
    public function find(int $id) { return new Pen(); }
    public function findAll() { return [new Pen()]; }
}

/**
 * @template T
 * @implements \IteratorAggregate<int, T>
 */
class IterableCollection implements \IteratorAggregate
{
    /** @return \ArrayIterator<int, T> */
    public function getIterator(): \ArrayIterator { return new \ArrayIterator([]); }
}

/** @extends IterableCollection<Pen> */
class ItemIterableCollection extends IterableCollection {}

/**
 * @template TKey of array-key
 * @template-covariant TValue
 */
class TypedCollection
{
    /** @var array<TKey, TValue> */
    protected array $items;

    /** @param array<TKey, TValue> $items */
    public function __construct(array $items = []) { $this->items = $items; }

    /** @return TValue */
    public function first() { return reset($this->items); }

    /** @return ?TValue */
    public function last() { return end($this->items) ?: null; }

    /** @return static */
    public function filter(callable $fn): static { return $this; }

    /** @return int */
    public function count(): int { return count($this->items); }

    /** @return array<TKey, TValue> */
    public function all(): array { return $this->items; }

    /**
     * Conditional @return whose branches are `static<...>` generics
     * (Laravel's `Collection::chunk()` shape). Chunking produces a
     * collection of collections, so the wrapped generic arguments must
     * survive the conditional to keep the inner element type resolvable.
     *
     * @return ($preserveKeys is true
     *     ? static<int, static>
     *     : static<int, static<int, TValue>>)
     */
    public function chunk(int $size, bool $preserveKeys = true): static
    {
        $chunks = array_chunk($this->items, $size, $preserveKeys);
        return new static(array_map(fn(array $c): static => new static($c), $chunks));
    }
}

/** @extends TypedCollection<int, Pen> */
class PenCollection extends TypedCollection
{
    public function thickOnly(): self
    {
        return $this;
    }
}

/** @phpstan-extends TypedCollection<string, Response> */
class ResponseCollection extends TypedCollection {}

// ─── Container (conditional return types) ───────────────────────────────────

class Container
{
    /** @var array<string, object> */
    private array $bindings = [];

    /**
     * @template TClass
     * @param string|null $abstract
     * @return ($abstract is class-string<TClass> ? TClass : mixed)
     */
    public function make(?string $abstract = null): mixed
    {
        if ($abstract === null) {
            return $this;
        }
        return $this->bindings[$abstract] ?? new $abstract();
    }

    public function bind(string $abstract, object $obj): void
    {
        $this->bindings[$abstract] = $obj;
    }

    public function getStatus(): int
    {
        return 200;
    }
}

// ─── Method-Level @template Classes ─────────────────────────────────────────

class ServiceLocator
{
    /**
     * @template T
     * @param class-string<T> $id
     * @return T
     */
    public function get(string $id): object
    {
        return new $id();
    }

    /**
     * @template T
     * @param class-string<T> ...$ids
     * @return T
     */
    public function getAny(string ...$ids): object
    {
        return new ($ids[0])();
    }

    /**
     * @template T
     * @param class-string<T> $id
     * @return Box<T>
     */
    public function wrap(string $id): object
    {
        return new Box(new $id());
    }

    /**
     * @template T of Pen
     * @param class-string<T> $id
     * @return T[]
     */
    public function getAll(string $id): array
    {
        return [new $id()];
    }

    /**
     * @template T of object
     * @param array<class-string<T>|T|array<T>> ...$args
     * @return T
     */
    public function build(mixed ...$args): object
    {
        $first = $args[0];

        return is_string($first) ? new $first() : $first;
    }
}

class Factory
{
    /**
     * @template T
     * @param class-string<T> $class
     * @return T
     */
    public static function create(string $class): object
    {
        return new $class();
    }
}

// ─── Generic Wrapper ────────────────────────────────────────────────────────

/**
 * @template T
 */
class Box
{
    /** @var T */
    public $value;

    /** @param T $value */
    public function __construct(mixed $value = null) { $this->value = $value; }

    /** @return T */
    public function unwrap() { return $this->value; }
}

class Gift
{
    public function open(): string { return 'surprise!'; }
    public function getTag(): string { return 'birthday'; }
}

// ─── Narrowing Demo Support Classes ─────────────────────────────────────────

class Rock
{
    public function crush(): string { return 'smash!'; }
    public function weigh(): float { return 5.0; }
}

class Banana
{
    public function peel(): string { return 'yum!'; }
    public function weigh(): float { return 0.2; }
}

class SpecimenHolder
{
    public Rock|Banana $item;

    public function __construct()
    {
        $this->item = new Rock();
    }

    public function maybe(): Rock|Banana|null
    {
        return null;
    }
}

// ─── Ambiguous Variable Support Classes ─────────────────────────────────────

class Lamp
{
    public function dim(): void {}
    public function turnOff(): void {}
}

class Faucet
{
    public function drip(): void {}
    public function turnOff(): void {}
}

// ─── Intersection Demo Support Classes ──────────────────────────────────────

interface Printable
{
    public function print(): void;
}

class Envelope
{
    public function seal(): void {}
}

class SealedEnvelope extends Envelope implements Printable
{
    public function print(): void {}
}

function openSealedEnvelope(): ?SealedEnvelope
{
    return new SealedEnvelope();
}

// ─── Shared Narrow Classes ──────────────────────────────────────────────────
// These are small, purpose-built classes for demos. Keep them narrow (2-4
// members each). If a demo needs a richer object, create a new class in a
// demo-specific section below instead of expanding these.

class Pen
{
    public function __construct(public string $ink = 'black') {}
    public function write(): string { return ''; }
    public function color(): string { return $this->ink; }
    public function label(): string { return 'pen'; }
    /** @return static */
    public function rename(string $name): static { return $this; }
    /** @return static */
    public static function make(string $color = 'black'): static { return new static($color); }
    private function refill(): void {}            // trip wire — must NOT appear on external $pen->
}

class Pencil
{
    public function sketch(): string { return ''; }
    public function sharpen(): void {}
    public function label(): string { return 'pencil'; }
}

class Marker extends Pen
{
    public function highlight(): void {}
}

// ─── Chaining Demo Support Classes ──────────────────────────────────────────

class Brush
{
    public function setSize(string $size): static { return $this; }
    public function setStyle(string $style): static { return $this; }
    public function stroke(): string { return ''; }
    public function getCanvas(): Canvas { return new Canvas(); }
    protected function calibrate(): void {}       // trip wire — must NOT appear on $studio->brush->
    public static function find(int $id): ?static { return null; }
}

class Canvas
{
    public Easel $easel;

    public function __construct() { $this->easel = new Easel(); }
    public function getBrush(): Brush { return new Brush(); }
    public function title(): string { return ''; }
}

class Easel
{
    public string $material = 'wood';
    public function height(): string { return '150cm'; }
}

// ─── Expression Type Support Classes ────────────────────────────────────────

class ElasticProductReviewIndexService
{
    public function index(array $markets = []): void {}
    public function reindex(): void {}
}

class ElasticBrandIndexService
{
    public function index(array $markets = []): void {}
    public function bulkDelete(array $ids): void {}
}

// ─── Param Override Support Classes ─────────────────────────────────────────

class Ingredient
{
    public function __construct(
        public string $name = '',
        public float $quantity = 0.0,
    ) {}

    public function format(): string
    {
        return "{$this->quantity}x {$this->name}";
    }
}

class Recipe
{
    /**
     * @param list<Ingredient> $ingredients
     */
    public function __construct(
        public string $name = '',
        public array $ingredients = [],
    ) {}
}

// ─── Trait Generic Support Classes ──────────────────────────────────────────

class UserFactory
{
    public function create(): User { return new User('', ''); }
    public function count(int $n): static { return $this; }
    public function state(array $state): static { return $this; }
    public function make(): User { return new User('', ''); }
}

/** @use HasFactory<UserFactory> */
class Product
{
    use HasFactory;

    public function getPrice(): float { return 0.0; }
    public function getSku(): string { return ''; }
}

// ─── Mixin Generic Scaffolding ─────────────────────────────────────────────

/**
 * @template TModel
 */
class ScaffoldingMixinBuilder
{
    /** @return TModel */
    public function firstOrFail(): mixed { return null; }
    /** @return TModel */
    public function find(): mixed { return null; }
}

/**
 * @template TRelatedModel
 * @mixin ScaffoldingMixinBuilder<TRelatedModel>
 */
class ScaffoldingMixinRelation
{
}

/**
 * @extends ScaffoldingMixinRelation<Product>
 */
class ScaffoldingMixinBelongsTo extends ScaffoldingMixinRelation
{
}

class ScaffoldingOrderLine
{
    public function product(): ScaffoldingMixinBelongsTo { return new ScaffoldingMixinBelongsTo(); }
}

/** @use Indexable<int, Pen> */
class PenIndex
{
    use Indexable;
}

// ─── Exception Classes ──────────────────────────────────────────────────────

class NotFoundException extends \RuntimeException {}
class ValidationException extends \RuntimeException {}
class AuthorizationException extends \RuntimeException {}

// ─── Standalone Functions ───────────────────────────────────────────────────

/**
 * @template TClass
 * @param string|null $abstract
 * @return ($abstract is class-string<TClass> ? TClass : Container)
 */
function app(?string $abstract = null): mixed
{
    static $container = null;
    if ($container === null) {
        $container = new Container();
    }
    return $abstract !== null ? $container->make($abstract) : $container;
}

/**
 * A conditional return type whose non-null branch is `mixed`. When `$key`
 * is a string, the value is of unknown type (`mixed`); otherwise it is
 * `null`. Mirrors Laravel's `session($key)` helper.
 *
 * @return ($key is string ? mixed : null)
 */
function sessionValue(?string $key = null)
{
    return $key !== null ? 'value' : null;
}

function createUser(string $name, string $email): User
{
    return new User($name, $email);
}

function makePen(): Pen
{
    return new Pen();
}

function pickPenOrPencil(): Pen|Pencil
{
    return new Pen();
}

function getUnknownValue(): mixed
{
    return new AdminUser('', '');
}

/**
 * @template T
 * @param class-string<T> $class The class name
 * @return T
 */
function resolve(string $class): object
{
    return new $class();
}

/**
 * @return array{logger: Pen, debug: bool}
 */
function getAppConfig(): array { return []; }

function pickRockOrBanana(): Rock|Banana
{
    return new Rock();
}

/** @return array<int, Pen>|false */
function loadPensOrFail(): array|false
{
    return [new Pen()];
}

/** @phpstan-assert Rock $value */
function assertRock(mixed $value): void
{
    if (!$value instanceof Rock) {
        throw new \InvalidArgumentException('Expected Rock');
    }
}

/** @phpstan-assert-if-true Rock $value */
function isRock(mixed $value): bool
{
    return $value instanceof Rock;
}

/** @phpstan-assert-if-false Rock $value */
function isNotRock(mixed $value): bool
{
    return !$value instanceof Rock;
}

class StaticAssert
{
    /** @phpstan-assert Rock $value */
    public static function assertRock(mixed $value): void
    {
        if (!$value instanceof Rock) {
            throw new \InvalidArgumentException('Expected Rock');
        }
    }

    /** @phpstan-assert-if-true Rock $value */
    public static function isRock(mixed $value): bool
    {
        return $value instanceof Rock;
    }

    /** @phpstan-assert-if-false Rock $value */
    public static function isNotRock(mixed $value): bool
    {
        return !$value instanceof Rock;
    }

    /** @phpstan-assert object $value */
    public static function assertIsObject(mixed $value): void
    {
        if (!is_object($value)) {
            throw new \InvalidArgumentException('Expected object');
        }
    }

    /** @phpstan-assert true $condition */
    public static function assertTrue(mixed $condition): void
    {
        if ($condition !== true) {
            throw new \InvalidArgumentException('Expected true');
        }
    }

    /** @phpstan-assert false $condition */
    public static function assertFalse(mixed $condition): void
    {
        if ($condition !== false) {
            throw new \InvalidArgumentException('Expected false');
        }
    }

    /** @phpstan-assert !string $value */
    public static function assertIsNotString(mixed $value): void
    {
        if (is_string($value)) {
            throw new \InvalidArgumentException('Did not expect string');
        }
    }
}

// ─── Pipe Operator / Pass-by-Reference / Interface Template / Generic Assert ─

function createPenFromString(string $input): Pen
{
    return new Pen();
}

function initPen(?Pen &$pen): void
{
    $pen = new Pen();
}

class PenFactory
{
    public static function create(?Pen &$pen): void
    {
        $pen = new Pen();
    }
}

class PenBuilder
{
    public function __construct(?Pen &$pen)
    {
        $pen = new Pen();
    }
}

interface ScaffoldingEntityFinder
{
    /**
     * @template T
     * @param class-string<T> $class
     * @return T
     */
    public function find(string $class): object;
}

class ScaffoldingEntityLocator implements ScaffoldingEntityFinder
{
    public function find(string $class): object
    {
        return new $class();
    }
}

class ScaffoldingAssert
{
    /**
     * @template ExpectedType of object
     * @param class-string<ExpectedType> $expected
     * @phpstan-assert ExpectedType $actual
     */
    public static function assertInstanceOf(string $expected, object $actual): void
    {
        if (!$actual instanceof $expected) {
            throw new \InvalidArgumentException('Type mismatch');
        }
    }
}

// ─── Multi-line @return & Broken Docblock Recovery ──────────────────────────

/**
 * @template TKey of array-key
 * @template TValue
 */
class FluentCollection
{
    /** @var array<TKey, TValue> */
    private array $items;

    /** @param array<TKey, TValue> $items */
    public function __construct(array $items = []) { $this->items = $items; }

    /**
     * @template TGroupKey of array-key
     *
     * @param  (callable(TValue, TKey): TGroupKey)|array|string  $groupBy
     * @param  bool  $preserveKeys
     * @return static<
     *  ($groupBy is (array|string)
     *      ? array-key
     *      : TGroupKey),
     *  static<($preserveKeys is true ? TKey : int), TValue>
     * >
     */
    public function groupBy($groupBy, $preserveKeys = false)
    {
    }

    /**
     * @param  TKey  $key
     * @return TValue|null
     */
    public function get($key)
    {
        return $this->items[$key] ?? null;
    }

    /**
     * @template TMapValue
     *
     * @param  callable(TValue, TKey): TMapValue  $callback
     * @return static<TKey, TMapValue>
     */
    public function map(callable $callback)
    {
    }

    /**
     * @param  callable(TValue, TKey): void  $callback
     * @return static<TKey, TValue>
     */
    public function each(callable $callback)
    {
        foreach ($this->items as $key => $value) {
            $callback($value, $key);
        }
        return $this;
    }

    /** @return TValue|null */
    public function first(): mixed
    {
        return $this->items[array_key_first($this->items)] ?? null;
    }

    /**
     * @return array<
     *   string,
     *   FluentCollection<int, TValue>
     * >
     */
    public function toGroupedArray()
    {
    }

    /**
     * @return static<TKey, TValue>
     */
    public function values()
    {
    }
}

/**
 * @template TKey of array-key
 * @template TValue
 * @param array<TKey, TValue> $value
 * @return FluentCollection<TKey, TValue>
 */
function collect(array $value = []): FluentCollection
{
    return new FluentCollection($value);
}

class BrokenDocRecovery
{
    /**
     * Broken multi-line @return — base `static` is recovered.
     * @return static<
     */
    public function broken(): static
    {
        return $this;
    }

    public function working(): string
    {
        return 'hello';
    }
}

// ── Runtime Assertions ──────────────────────────────────────────────────────
// Verify that the type claims in demo comments match reality.
// Run: php examples/demo.php

function runDemoAssertions(): void
{
    // ── Body Return Type Inference ──────────────────────────────────────
    $factory = new ScaffoldingUntypedFactory();
    $pen = $factory->createPen();
    assert($pen instanceof Pen, 'createPen() must return Pen (inferred from body)');
    $tool = $factory->createTool(true);
    assert($tool instanceof Pen || $tool instanceof Pencil, 'createTool() must return Pen|Pencil');

    // ── Leading-backslash (absolute) function call ─────────────────────
    assert(\Demo\makePen() instanceof Pen, 'absolute \\Demo\\makePen() resolves the same as makePen()');

    // ── Trait `return $this` fluent chain ───────────────────────────────
    $page = new TestablePage();
    assert($page->assertSee('a') instanceof TestablePage, 'trait return $this resolves to the using class');
    assert($page->assertSee('a')->assertSee('b')->status === 200, 'chained trait return $this keeps the using class members');

    // ── Ternary Condition Narrowing ─────────────────────────────────────
    $penTool = new TernaryNarrowingDemo(new Pen());
    assert($penTool->toolLabel() === '', 'ternary then-branch narrows property to Pen; ->write() returns ""');
    assert($penTool->repeatedCall() === '', 'ternary truthy narrows method-call subject to Pen');
    $pencilTool = new TernaryNarrowingDemo(new Pencil());
    assert($pencilTool->toolLabel() === null, 'ternary else-branch yields null (Pencil is not a Pen)');
    assert($pencilTool->repeatedCall() === null, 'ternary else-branch yields null for repeated call');

    // ── class-string guard keeps its type argument ─────────────────────
    $guarded = (new ClassStringVarDemo())->guardedInstantiation(Pen::class);
    assert($guarded instanceof Pen, 'new $className() resolves to Pen after a class_exists() guard');

    // ── property_exists() narrowing ─────────────────────────────────────
    // The dynamic fields are populated through a variable property name so the
    // runtime setup mirrors how these responses are filled in real code.
    $memberDemo = new MemberExistsNarrowingDemo();
    $response = new ApiResponse();
    $field = 'errorMessage';
    $response->$field = 'boom';                    // dynamically populated
    assert($memberDemo->property($response) === 'boom', 'property_exists guard reads the dynamic property');
    assert($memberDemo->property(new ApiResponse()) === null, 'no property → guard is false');
    $withDetail = new ApiResponse();
    $field = 'detail';
    $withDetail->$field = 'context';
    assert($memberDemo->guardClause($withDetail) === 'context', 'negated property_exists guard clause reads the property after it');
    assert($memberDemo->guardClause(new ApiResponse()) === 'none', 'guard clause returns early when the property is absent');
    $issetResp = new ApiResponse();
    $field = 'errorMessage';
    $issetResp->$field = 'boom';
    assert($memberDemo->issetGuard($issetResp) === 'boom', 'isset($obj->prop) guard reads the dynamic property');
    assert($memberDemo->issetGuard(new ApiResponse()) === null, 'isset guard is false when the property is absent');
    $ternaryResp = new ApiResponse();
    $field = 'detail';
    $ternaryResp->$field = 'd';
    $field = 'errorMessage';
    $ternaryResp->$field = 'e';
    assert($memberDemo->ternary($ternaryResp) === 'd|e', 'property_exists and isset ternaries read the proven properties');
    assert($memberDemo->ternary(new ApiResponse()) === 'none|none', 'member-existence ternaries fall back when the properties are absent');

    // ── array<T>|false keeps its element type after a false check ────────
    $pens = loadPensOrFail();
    assert($pens !== false && $pens[0] instanceof Pen, 'loadPensOrFail() returns array<int, Pen> on success');

    // ── @phpstan-require-extends base members on $this ──────────────────
    $consumer = new RequireExtendsConsumer();
    assert($consumer->mockPath() === '/tmp/mock', 'trait method reaches base class member via @phpstan-require-extends');

    // ── Pseudo-type class-name collision ────────────────────────────────
    $num = new Number('42');
    assert($num->scaled(2) instanceof Number, 'Number::scaled() must return Number (class, not pseudo-type)');
    assert(scaleNumber($num) instanceof Number, 'scaleNumber() must accept and return a Number');

    // ── Return Type: static ─────────────────────────────────────────────
    $pen = Pen::make();
    assert($pen instanceof Pen, 'Pen::make() must return Pen');

    $marker = Marker::make();
    assert($marker instanceof Marker, 'Marker::make() must return Marker (not Pen)');

    $fluent = $marker->rename('Bold');
    assert($fluent instanceof Marker, 'Marker::rename() returns static, must stay Marker');

    // ── Return Type: function ───────────────────────────────────────────
    $created = makePen();
    assert($created instanceof Pen, 'makePen() must return Pen');

    $union = pickPenOrPencil();
    assert($union instanceof Pen || $union instanceof Pencil, 'pickPenOrPencil() must return Pen|Pencil');

    $rock = pickRockOrBanana();
    assert($rock instanceof Rock || $rock instanceof Banana, 'pickRockOrBanana() must return Rock|Banana');

    $user = createUser('Alice', 'alice@example.com');
    assert($user instanceof User, 'createUser() must return User');

    // ── Chaining ────────────────────────────────────────────────────────
    $brush = new Brush();
    $sized = $brush->setSize('large');
    assert($sized instanceof Brush, 'Brush::setSize() returns static, must stay Brush');
    $styled = $sized->setStyle('pointed');
    assert($styled instanceof Brush, 'Brush::setStyle() returns static, must stay Brush');

    $canvas = $brush->getCanvas();
    assert($canvas instanceof Canvas, 'Brush::getCanvas() must return Canvas');

    $backToBrush = $canvas->getBrush();
    assert($backToBrush instanceof Brush, 'Canvas::getBrush() must return Brush');

    $easel = $canvas->easel;
    assert($easel instanceof Easel, 'Canvas::$easel must be Easel');

    // ── Inferred nested tuple literals ──────────────────────────────────
    $rows = [[new Pen(), new Pencil()]];
    foreach ($rows as $row) {
        assert($row[0] instanceof Pen, 'nested tuple index 0 must be Pen');
        assert($row[1] instanceof Pencil, 'nested tuple index 1 must be Pencil');
    }

    // Indexing a position only some arms have, with a `?? Class::class`
    // fallback, stays a class-string that instantiates Pen|Pencil.
    $specs = [['pen', Pen::class], ['pencil']];
    foreach ($specs as $spec) {
        $toolClass = $spec[1] ?? Pencil::class;
        assert(class_exists($toolClass), 'index + ?? fallback must yield a class-string');
        $tool = new $toolClass();
        assert($tool instanceof Pen || $tool instanceof Pencil, 'class-string must instantiate Pen|Pencil');
    }

    // ── Indexing an ArrayAccess Object ───────────────────────────────────
    $penAccess = new ScaffoldingPenArrayAccess();
    assert($penAccess[0] instanceof Pen, 'ArrayAccess[0] must resolve via offsetGet(): Pen');

    $genericAccess = new ScaffoldingGenericArrayAccess([new Pen()]);
    assert($genericAccess[0] instanceof Pen, 'ArrayAccess<int, T>[0] must resolve T bound to Pen');

    // ── Conditional @return with nested static<...> generic branches ────
    /** @var TypedCollection<int, Pen> $penItems */
    $penItems = new TypedCollection([new Pen()]);
    $penBatches = $penItems->chunk(1);
    assert(
        $penBatches->first()->first() instanceof Pen,
        'Collection::chunk() conditional return keeps the nested collection element type'
    );

    // ── Fluent Model chains (static return) ─────────────────────────────
    $userObj = new User('Bob', 'bob@example.com');
    $renamed = $userObj->setName('Robert');
    assert($renamed instanceof User, 'User::setName() returns static, must stay User');

    $timestamped = $userObj->setCreatedAt('2024-01-01');
    assert($timestamped instanceof User, 'HasTimestamps::setCreatedAt() returns static, must stay User');

    // ── User method return types ────────────────────────────────────────
    $profile = $userObj->getProfile();
    assert($profile instanceof UserProfile, 'User::getProfile() must return UserProfile');

    $status = $userObj->getStatus();
    assert($status instanceof Status, 'User::getStatus() must return Status');

    // ── Type narrowing: instanceof ──────────────────────────────────────
    $specimen = pickRockOrBanana();
    if ($specimen instanceof Rock) {
        assert(method_exists($specimen, 'crush'), 'Rock must have crush()');
    } else {
        assert($specimen instanceof Banana, 'Not Rock must be Banana');
        assert(method_exists($specimen, 'peel'), 'Banana must have peel()');
    }

    // ── Type narrowing: inline && ───────────────────────────────────────
    $sample = pickRockOrBanana();
    if ($sample instanceof Rock && $sample->crush()) {
        assert($sample instanceof Rock, 'RHS of && must see Rock');
    }

    // ── Type narrowing: negated instanceof ──────────────────────────────
    $specimen2 = pickRockOrBanana();
    if (!$specimen2 instanceof Rock) {
        assert($specimen2 instanceof Banana, 'Not Rock must be Banana');
    }

    // ── Type narrowing: assert() ────────────────────────────────────────
    $target = pickRockOrBanana();
    if ($target instanceof Banana) {
        assert(method_exists($target, 'peel'), 'assert narrowed Banana must have peel()');
    }

    // ── Custom assert functions ─────────────────────────────────────────
    $unknown = new Rock();
    assertRock($unknown);
    assert($unknown instanceof Rock, 'assertRock() must narrow to Rock');

    assert(isRock(new Rock()) === true, 'isRock(Rock) must return true');
    assert(isRock(new Banana()) === false, 'isRock(Banana) must return false');
    assert(isNotRock(new Rock()) === false, 'isNotRock(Rock) must return false');
    assert(isNotRock(new Banana()) === true, 'isNotRock(Banana) must return true');

    // ── Static assert functions ─────────────────────────────────────────
    $unknown2 = new Rock();
    StaticAssert::assertRock($unknown2);
    assert($unknown2 instanceof Rock, 'StaticAssert::assertRock() must narrow to Rock');

    assert(StaticAssert::isRock(new Rock()) === true, 'StaticAssert::isRock(Rock) must return true');
    assert(StaticAssert::isNotRock(new Banana()) === true, 'StaticAssert::isNotRock(Banana) must return true');

    // ── Null-init + foreach reassignment (B11) ──────────────────────────
    $pens = [new Pen('blue'), new Pen('red')];
    $found = null;
    foreach ($pens as $pen) {
        if ($pen->color() === 'blue') {
            $found = $pen;
        }
    }
    assert($found instanceof Pen, 'Null-init + foreach reassign must resolve to Pen');
    assert(method_exists($found, 'write'), 'Pen from foreach must have write()');

    // ── instanceof self/static/parent ───────────────────────────────────
    $sedan = new ScaffoldingSedan();
    assert($sedan instanceof ScaffoldingMotor, 'ScaffoldingSedan must extend ScaffoldingMotor');
    assert(method_exists($sedan, 'cruise'), 'ScaffoldingSedan must have cruise()');
    assert(method_exists($sedan, 'start'), 'ScaffoldingSedan must inherit start()');

    $demo = new InstanceofSelfDemo();
    assert($demo instanceof ScaffoldingSedan, 'InstanceofSelfDemo must extend ScaffoldingSedan');
    assert(method_exists($demo, 'sport'), 'InstanceofSelfDemo must have sport()');
    assert(method_exists($demo, 'cruise'), 'InstanceofSelfDemo must inherit cruise()');

    // ── Method-level @template (runtime resolution) ─────────────────────
    $locator = new ServiceLocator();
    $locatedPen = $locator->get(Pen::class);
    assert($locatedPen instanceof Pen, 'ServiceLocator::get(Pen::class) must return Pen');

    // A single-quoted class-string literal names the class after the source
    // `\\` escape is collapsed to a single namespace separator.
    assert($locator->get('Demo\\Pen') instanceof Pen, "ServiceLocator::get('Demo\\\\Pen') must return Pen");

    // A union of class-strings binds the bounded template to the union of
    // concrete classes; each member's stub returns an instance of itself.
    foreach ([Pen::class, Marker::class] as $penClass) {
        $group = $locator->getAll($penClass);
        assert($group[0] instanceof $penClass, 'getAll() must return an instance of each class in the union');
    }

    // Indexing the call result inline keeps the template binding.
    assert($locator->getAll(Pen::class)[0] instanceof Pen, 'getAll(Pen::class)[0] must be a Pen');

    // A class-string<T>|T union parameter accepts a class name or an
    // instance and returns an instance either way.
    assert($locator->build(Pen::class) instanceof Pen, 'build(Pen::class) must return a Pen instance');
    assert($locator->build(new Pen()) instanceof Pen, 'build(new Pen()) must return a Pen instance');

    $createdPen = Factory::create(Pen::class);
    assert($createdPen instanceof Pen, 'Factory::create(Pen::class) must return Pen');

    $resolved = resolve(Marker::class);
    assert($resolved instanceof Marker, 'resolve(Marker::class) must return Marker');

    // ── ObjectMapper::wrap() → TypedCollection ──────────────────────────
    $mapper = new ObjectMapper();
    $wrapped = $mapper->wrap(new Pen());
    assert($wrapped instanceof TypedCollection, 'ObjectMapper::wrap() must return TypedCollection');
    $first = $wrapped->first();
    assert($first instanceof Pen, 'wrap(Pen)->first() must return Pen');

    // Untyped class constant argument binds the template to its value type (int).
    $constValue = $mapper->identity(ConstantTypeDemo::TIMEOUT);
    assert(is_int($constValue), 'identity(ConstantTypeDemo::TIMEOUT) must return int (constant value type, not owning class)');

    // A `::class` argument binds `@param T` to a class-string, so the
    // returned value is the fully-qualified class name string.
    $penClass = $mapper->identity(Pen::class);
    assert($penClass === Pen::class, 'identity(Pen::class) must return the class-string Pen::class');

    // An identity generic bound to an array type (`@template T of Pen[]`)
    // must still return the array unchanged.
    $peeked = $mapper->peekLast([new Pen('blue')]);
    assert(end($peeked) instanceof Pen, 'peekLast() must return its argument unchanged');

    // ── ScaffoldingReducible::reduce() — closure return type binding ────
    /** @var ScaffoldingReducible<Pencil> $reducible */
    $reducible = new ScaffoldingReducible();
    $reduced = $reducible->reduce(
        fn(Pen $carry, Pencil $item): Pen => $carry,
        new Pen('starter')
    );
    assert($reduced instanceof Pen, 'reduce() with fn(): Pen must return Pen');

    // Chained call: reduce() result used directly without intermediate variable.
    $chainedWrite = $reducible->reduce(fn(Pen $carry, Pencil $item): Pen => $carry, new Pen('starter'))->write();
    assert(is_string($chainedWrite), 'reduce()->write() chained must return string (Pen::write() return type)');

    // Unannotated closure: the return type follows from the body expression
    // resolved through the closure's own typed parameter.
    $inferredReduce = $reducible->reduce(
        fn(Pen $carry, $item) => $carry->rename('merged'),
        new Pen('starter')
    );
    assert($inferredReduce instanceof Pen, 'reduce(fn(Pen $carry, $item) => $carry->rename(...)) must return Pen (inferred from body)');

    // ── ScaffoldingClosureCache::remember() — unannotated closure body ──
    $cache = new ScaffoldingClosureCache();
    $cachedPen = $cache->remember('pen', fn() => new Pen('cached'));
    assert($cachedPen instanceof Pen, 'remember(fn() => new Pen()) must return Pen (T from arrow body)');
    $cachedMarker = $cache->remember('marker', function () {
        return new Marker('cached');
    });
    assert($cachedMarker instanceof Marker, 'remember(function () { return new Marker(); }) must return Marker (T from closure body)');

    // ── ScaffoldingEventBus::listen() — closure param type binding ──────
    $bus = new ScaffoldingEventBus();
    $listened = $bus->listen(function(Pen $p): void { $p->write(); });
    assert($listened instanceof Pen, 'listen(fn(Pen $p)) must return Pen (T inferred from closure param)');

    $listenedUser = $bus->listen(function(User $u): void { $u->getEmail(); });
    assert($listenedUser instanceof User, 'listen(function(User $u)) must return User');

    // ── ScaffoldingBatchProcessor::process() — second closure param ─────
    $proc = new ScaffoldingBatchProcessor();
    $processed = $proc->process(function(int $i, Pencil $p): void { $p->sketch(); });
    assert($processed instanceof Pencil, 'process(fn(int, Pencil)) must return Pencil (T from position 1)');

    // ── Nested generic: ServiceLocator::wrap → Box::unwrap ──────────────
    $boxed = $locator->wrap(Pen::class);
    assert($boxed instanceof Box, 'ServiceLocator::wrap() must return Box');
    $unboxed = $boxed->unwrap();
    assert($unboxed instanceof Pen, 'Box::unwrap() must return Pen (from wrap(Pen::class))');

    // ── __invoke() return types ─────────────────────────────────────────
    $formatter = new ScaffoldingFormatter();
    $invoked = $formatter();
    assert($invoked instanceof Pen, 'ScaffoldingFormatter::__invoke() must return Pen');

    $factory = new ScaffoldingPenFactory();
    $factoryResult = $factory();
    assert($factoryResult instanceof Pen, 'ScaffoldingPenFactory::__invoke() must return Pen');

    // ── Enum from() ─────────────────────────────────────────────────────
    $active = Status::from('active');
    assert($active instanceof Status, 'Status::from() must return Status');
    assert($active === Status::Active, 'Status::from("active") must be Status::Active');

    // ── Clone preserves type ────────────────────────────────────────────
    $original = new Pen('blue');
    $copy = clone $original;
    assert($copy instanceof Pen, 'clone must preserve Pen type');
    assert($copy !== $original, 'clone must be a different instance');

    // ── class-string variable → new $var ────────────────────────────────
    $cls = Pen::class;
    $fromClassString = new $cls();
    assert($fromClassString instanceof Pen, 'new $cls where $cls = Pen::class must be Pen');

    // ── Zoo: inheritance, traits, promoted properties ────────────────────
    $zoo = new Zoo();
    assert($zoo instanceof Zoo, 'new Zoo() must be Zoo');
    assert($zoo instanceof ZooBase, 'Zoo must extend ZooBase');
    assert(method_exists($zoo, 'aardvark'), 'Zoo must have own method aardvark()');
    assert(method_exists($zoo, 'dingo'), 'Zoo must have trait method dingo()');
    assert(method_exists($zoo, 'elephant'), 'Zoo must have trait method elephant()');
    assert(method_exists($zoo, 'falcon'), 'Zoo must have inherited method falcon()');

    // @property and @method via __get/__call
    assert($zoo->gorilla === 'gorilla-value', '@property $gorilla must work via __get');
    assert($zoo->iguana === 'iguana-value', '@property-read $iguana (ZooContract) must work via __get');
    assert($zoo->hyena('x') === true, '@method hyena() must work via __call');
    assert($zoo->jaguar() === 'jaguar-value', '@method jaguar() (ZooContract) must work via __call');

    // Visibility: protected/private must not be accessible
    assert(property_exists($zoo, 'baboon'), 'Zoo must have public $baboon');
    assert((new \ReflectionProperty($zoo, 'keeper'))->isProtected(), '$keeper must be protected');
    assert((new \ReflectionProperty($zoo, 'ceo'))->isPrivate(), '$ceo must be private');
    assert((new \ReflectionMethod($zoo, 'nocturnal'))->isPrivate(), 'nocturnal() must be private');

    // ── Expression types: null-coalescing ────────────────────────────────
    $src = new ScaffoldingExpressionType();
    $fallback = $src->backup ?? $src->primary;
    assert($fallback instanceof Response, 'Null-coalescing must resolve to Response');

    // ── ChainingDemo scaffolding ────────────────────────────────────────
    $studio = new ScaffoldingChainingDemo();
    assert($studio->brush instanceof Brush, 'ScaffoldingChainingDemo::$brush must be Brush');
    assert($studio->canvas instanceof Canvas, 'ScaffoldingChainingDemo::$canvas must be Canvas');

    // ── Trait conflict resolution ───────────────────────────────────────
    $tc = new TraitConflictDemo();
    assert(method_exists($tc, 'serialize'), 'TraitConflictDemo must have serialize()');
    assert(method_exists($tc, 'toJson'), 'TraitConflictDemo must have toJson()');
    assert(method_exists($tc, 'toXml'), 'TraitConflictDemo must have toXml()');

    // ── AdminUser extends User extends Model ────────────────────────────
    $admin = new AdminUser('Admin', 'admin@example.com');
    assert($admin instanceof AdminUser, 'new AdminUser() must be AdminUser');
    assert($admin instanceof User, 'AdminUser must extend User');
    assert($admin instanceof Model, 'AdminUser must extend Model (via User)');

    // ── ClassFilteringDemo extends Model implements Renderable ───────────
    $cfd = new ClassFilteringDemo();
    assert($cfd instanceof Model, 'ClassFilteringDemo must extend Model');
    assert($cfd instanceof Renderable, 'ClassFilteringDemo must implement Renderable');

    // ── Inline new chaining ─────────────────────────────────────────────
    $fromNew = (new Canvas())->getBrush();
    assert($fromNew instanceof Brush, '(new Canvas())->getBrush() must be Brush');

    // ── Parenthesized assignment ────────────────────────────────────────
    $parenPen = (new Pen('red'));
    assert($parenPen instanceof Pen, 'Parenthesized new must still be Pen');

    // ── Constructor @param override (ParamOverrideDemo) ─────────────────
    $ingredient = new Ingredient();
    assert($ingredient instanceof Ingredient, 'new Ingredient() must be Ingredient');
    assert(property_exists($ingredient, 'name'), 'Ingredient must have $name');

    $recipe = new Recipe('Test', [new Ingredient()]);
    assert($recipe instanceof Recipe, 'new Recipe() must be Recipe');

    // ── Inline @var on promoted property (InlineVarPromotedDemo) ────────
    $inlineDemo = new InlineVarPromotedDemo([new Ingredient()]);
    assert(is_array($inlineDemo->ingredients), 'InlineVarPromotedDemo->ingredients must be array');
    assert($inlineDemo->ingredients[0] instanceof Ingredient, 'InlineVarPromotedDemo->ingredients[0] must be Ingredient');

    // ── Container / app() conditional return types ──────────────────────
    $container = new Container();
    $containerPen = $container->make(Pen::class);
    assert($containerPen instanceof Pen, 'Container::make(Pen::class) must return Pen');

    $appPen = app(Pen::class);
    assert($appPen instanceof Pen, 'app(Pen::class) must return Pen');

    $appSelf = app();
    assert($appSelf instanceof Container, 'app() with no args must return Container');

    // ── Named-argument conditional return type ──────────────────────────
    $mapper = new TreeMapperImpl();
    $named = $mapper->map(source: 'bar', signature: 'foo');
    assert($named instanceof Pen, 'out-of-order named args bind $signature="foo" → Pen');

    // ── Conditional branch selecting `mixed` flows through ──────────────
    $unknown = sessionValue('file');
    assert(is_string($unknown), 'sessionValue("file") returns a mixed value narrowable to string');
    assert(sessionValue() === null, 'sessionValue() with no args returns null');

    // ── Closure / arrow function return types ───────────────────────────
    $makePenClosure = function(): Pen { return new Pen(); };
    assert($makePenClosure() instanceof Pen, 'Closure returning Pen must return Pen');

    $makePencilArrow = fn(): Pencil => new Pencil();
    assert($makePencilArrow() instanceof Pencil, 'Arrow fn returning Pencil must return Pencil');

    $builder = function(): Pen { return new Pen(); };
    $chained = $builder()->rename('Bold');
    assert($chained instanceof Pen, 'Closure()->rename() must chain to Pen');

    // ── Closure members ─────────────────────────────────────────────────
    $typedClosure = function(Pen $pen): string { return $pen->write(); };
    assert(method_exists($typedClosure, 'bindTo'), 'Closure must have bindTo()');
    assert(method_exists($typedClosure, 'call'), 'Closure must have call()');
    assert($typedClosure instanceof \Closure, 'Function expression must be Closure');

    $typedArrow = fn(int $x): float => $x * 1.5;
    assert($typedArrow instanceof \Closure, 'Arrow function must be Closure');

    // ── Enum methods and properties ─────────────────────────────────────
    $activeStatus = Status::Active;
    assert($activeStatus instanceof Status, 'Status::Active must be Status');
    assert($activeStatus->name === 'Active', 'Status::Active->name must be "Active"');
    assert($activeStatus->value === 'active', 'Status::Active->value must be "active"');
    assert($activeStatus->label() === 'Active', 'Status::Active->label() must return "Active"');
    assert($activeStatus->isActive() === true, 'Status::Active->isActive() must be true');

    $pending = Status::Pending;
    assert($pending->isActive() === false, 'Status::Pending->isActive() must be false');

    $high = Priority::High;
    assert($high instanceof Priority, 'Priority::High must be Priority');
    assert($high->name === 'High', 'Priority::High->name must be "High"');
    assert($high->value === 3, 'Priority::High->value must be 3');

    $manual = Mode::Manual;
    assert($manual instanceof Mode, 'Mode::Manual must be Mode');
    assert($manual->name === 'Manual', 'Mode::Manual->name must be "Manual"');

    // cases() returns a list of the enum's own instances; indexing it
    // inline resolves the element back to the enum.
    assert(Status::cases()[0] instanceof Status, 'Status::cases()[0] must be a Status');
    assert(Status::cases()[0]->value === 'active', 'Status::cases()[0]->value must be "active"');
    assert(Priority::cases()[0]->name === 'Low', 'Priority::cases()[0]->name must be "Low"');

    $fromString = Status::from('active');
    assert($fromString === Status::Active, 'Status::from("active") must be Status::Active');

    $tryFrom = Status::tryFrom('nonexistent');
    assert($tryFrom === null, 'Status::tryFrom("nonexistent") must be null');

    $defaultVal = Status::defaultValue();
    assert($defaultVal === 'active', 'Status::defaultValue() must return "active" (self::Active->value)');

    // ── Response methods ────────────────────────────────────────────────
    $response = new Response(200, 'OK');
    assert($response->getStatusCode() === 200, 'Response::getStatusCode() must return 200');
    assert($response->getBody() === 'OK', 'Response::getBody() must return "OK"');
    assert($response->isSuccess() === true, 'Response(200) must be success');

    $errResponse = new Response(500);
    assert($errResponse->isSuccess() === false, 'Response(500) must not be success');

    // ── UserProfile methods ─────────────────────────────────────────────
    $userForProfile = new User('Eve', 'eve@example.com');
    $prof = $userForProfile->getProfile();
    assert($prof instanceof UserProfile, 'User::getProfile() must return UserProfile');
    assert(method_exists($prof, 'getDisplayName'), 'UserProfile must have getDisplayName()');
    assert(method_exists($prof, 'setBio'), 'UserProfile must have setBio()');
    $bioResult = $prof->setBio('Hello');
    assert($bioResult instanceof UserProfile, 'UserProfile::setBio() returns static');

    // ── Generator yield types ───────────────────────────────────────────
    $genDemo = new GeneratorDemo();
    $gen = $genDemo->getPens();
    assert($gen instanceof \Generator, 'getPens() must return Generator');
    foreach ($gen as $genPen) {
        assert($genPen instanceof Pen, 'Generator<int, Pen> must yield Pen');
        break;
    }

    $pencilGen = $genDemo->processPencils();
    foreach ($pencilGen as $genPencil) {
        assert($genPencil instanceof Pencil, 'Generator<int, Pencil, mixed, Pen> must yield Pencil');
        break;
    }

    // ── Generator yield inference (GeneratorYieldDemo) ───────────────────
    $yieldDemo = new GeneratorYieldDemo();
    foreach ($yieldDemo->findAll() as $yieldedPen) {
        assert($yieldedPen instanceof Pen, 'GeneratorYieldDemo::findAll() must yield Pen');
        break;
    }
    foreach ($yieldDemo->chainingThroughYieldInferred() as $chainPen) {
        assert($chainPen instanceof Pen, 'chainingThroughYieldInferred() must yield Pen');
        break;
    }
    $coroutineGen = $yieldDemo->coroutine();
    $yielded = $coroutineGen->current();
    assert($yielded === 'ready', 'coroutine() must yield string (TValue)');
    $coroutineGen->send(new Pencil());

    // ── GenericContext: Box<Gift> and TypedCollection<int, Gift> ─────────
    $gcSrc = new ScaffoldingGenericContext();
    $unwrapped = $gcSrc->chest->unwrap();
    assert($unwrapped instanceof Gift, 'Box<Gift>::unwrap() must return Gift');
    $displayFirst = $gcSrc->display()->first();
    assert($displayFirst instanceof Gift, 'TypedCollection<int, Gift>::first() must return Gift');

    // ── CompoundNegatedNarrowing ────────────────────────────────────────
    $compoundRock = new Rock();
    $compoundDemo = new CompoundNegatedNarrowingDemo();
    // Rock passes both negated checks (is Rock, is not "not Rock")
    // so it doesn't return early — weigh() must exist
    assert(method_exists($compoundRock, 'weigh'), 'Rock must have weigh()');
    $compoundBanana = new Banana();
    assert(method_exists($compoundBanana, 'weigh'), 'Banana must have weigh()');
    // Lamp would cause the early return — verify it lacks weigh()
    assert(!method_exists(new Lamp(), 'weigh'), 'Lamp must NOT have weigh()');

    // ── InArrayNarrowing ────────────────────────────────────────────────
    $rockList = [new Rock()];
    $testRock = new Rock();
    assert(in_array($testRock, $rockList, true) === false, 'Different Rock instances are not strictly identical');
    $sameRock = $rockList[0];
    assert(in_array($sameRock, $rockList, true) === true, 'Same Rock instance must be in_array strict');

    // ── MatchClassStringDemo: class-string through match → Container ────
    $mcsContainer = new Container();
    $mcsType = match (0) {
        0 => ElasticProductReviewIndexService::class,
        1 => ElasticBrandIndexService::class,
    };
    $mcsResult = $mcsContainer->make($mcsType);
    assert($mcsResult instanceof ElasticProductReviewIndexService,
        'Container::make(match class-string) must return the matched class');
    assert(method_exists($mcsResult, 'index'), 'Match-resolved instance must have index()');

    $mcsCls = Pen::class;
    $mcsPen = $mcsContainer->make($mcsCls);
    assert($mcsPen instanceof Pen, 'Container::make(Pen::class via variable) must return Pen');

    $mcsTernary = true ? Pen::class : Pencil::class;
    $mcsObj = $mcsContainer->make($mcsTernary);
    assert($mcsObj instanceof Pen, 'Container::make(ternary class-string) must return Pen');

    // ── ExceptionDemo: exception hierarchy ──────────────────────────────
    assert(is_subclass_of(NotFoundException::class, \RuntimeException::class),
        'NotFoundException must extend RuntimeException');
    assert(is_subclass_of(ValidationException::class, \RuntimeException::class),
        'ValidationException must extend RuntimeException');
    assert(is_subclass_of(AuthorizationException::class, \RuntimeException::class),
        'AuthorizationException must extend RuntimeException');

    try {
        throw new ValidationException('test');
    } catch (ValidationException $e) {
        assert($e instanceof ValidationException, 'Caught exception must be ValidationException');
        assert($e->getMessage() === 'test', 'Exception message must propagate');
    }

    // ── Closure parameter inference ─────────────────────────────────────
    $closureSrc = new ScaffoldingClosureParamInference();
    $closureReceived = [];
    $closureSrc->items->each(function ($pen) use (&$closureReceived) {
        assert($pen instanceof Pen, 'Closure param from FluentCollection<int, Pen>::each() must be Pen');
        $closureReceived[] = $pen;
    });
    assert(count($closureReceived) === 2, 'each() must invoke callback for every item');

    // Function-level @template callable inference (array_any pattern)
    $tplHolder = new ScaffoldingTemplateCallableHolder();
    $tplHolder->tools = [new Pen('red'), new Pen('blue')];
    $tplResult = array_any($tplHolder->tools, fn($t) => $t->color() === 'red');
    assert($tplResult === true, 'array_any with template callable must work');

    // ── Type alias resolution ───────────────────────────────────────────
    $aliasDemo = new TypeAliasDemo();
    $userData = $aliasDemo->getUserData();
    assert(is_string($userData['name']), 'UserData["name"] must be string');
    assert($userData['pen'] instanceof Pen, 'UserData["pen"] must be Pen');

    $statusInfo = $aliasDemo->getStatus();
    assert(is_int($statusInfo['code']), 'StatusInfo["code"] must be int');
    assert($statusInfo['owner'] instanceof User, 'StatusInfo["owner"] must be User');

    $importDemo = new TypeAliasImportDemo();
    $imported = $importDemo->fetchUser();
    assert($imported['pen'] instanceof Pen, 'Imported UserData["pen"] must be Pen');
    $importedStatus = $importDemo->fetchStatus();
    assert($importedStatus['owner'] instanceof User, 'Imported StatusInfo["owner"] must be User');

    // ── String interpolation ────────────────────────────────────────────
    $interpPen = new Pen('blue');
    ob_start();
    echo "Ink is {$interpPen->color()}";
    $braceOutput = ob_get_clean();
    assert($braceOutput === 'Ink is blue', 'Brace interpolation must call method: got ' . $braceOutput);

    ob_start();
    echo "Tool: $interpPen->ink";
    $simpleOutput = ob_get_clean();
    assert($simpleOutput === 'Tool: blue', 'Simple interpolation must access property: got ' . $simpleOutput);

    ob_start();
    echo 'no $interpPen-> here';
    $singleOutput = ob_get_clean();
    assert($singleOutput === 'no $interpPen-> here', 'Single-quoted must stay literal: got ' . $singleOutput);

    // ── Diagnostics: class/method/property existence ────────────────────
    // These verify the claims made by the UnknownMemberDemo and related demos.
    assert(class_exists(User::class), 'User class must exist');
    assert(class_exists(Pen::class), 'Pen class must exist');
    assert(class_exists(Model::class), 'Model class must exist');
    assert(class_exists(AdminUser::class), 'AdminUser class must exist');
    assert(interface_exists(Renderable::class), 'Renderable interface must exist');
    assert(trait_exists(HasTimestamps::class), 'HasTimestamps trait must exist');
    assert(trait_exists(HasSlug::class), 'HasSlug trait must exist');
    assert(enum_exists(Status::class), 'Status enum must exist');
    assert(enum_exists(Priority::class), 'Priority enum must exist');

    // User members that demos reference
    assert(method_exists(User::class, 'getEmail'), 'User must have getEmail()');
    assert(method_exists(User::class, 'getName'), 'User must have getName() (inherited)');
    assert(method_exists(User::class, 'getProfile'), 'User must have getProfile()');
    assert(method_exists(User::class, 'getStatus'), 'User must have getStatus()');
    assert(method_exists(User::class, 'setName'), 'User must have setName() (inherited)');
    assert(method_exists(User::class, 'findByEmail'), 'User must have static findByEmail()');
    assert(method_exists(User::class, 'hashPassword'), 'User must have static hashPassword()');
    assert(property_exists(User::class, 'email'), 'User must have $email');
    assert(property_exists(User::class, 'defaultRole'), 'User must have static $defaultRole');

    // UnknownMemberDemo: nonexistentMethod must NOT exist
    assert(!method_exists(User::class, 'nonexistentMethod'), 'User must NOT have nonexistentMethod()');

    // Pen members
    assert(method_exists(Pen::class, 'write'), 'Pen must have write()');
    assert(method_exists(Pen::class, 'color'), 'Pen must have color()');
    assert(method_exists(Pen::class, 'label'), 'Pen must have label()');
    assert(method_exists(Pen::class, 'rename'), 'Pen must have rename()');
    assert(method_exists(Pen::class, 'make'), 'Pen must have static make()');

    // Marker extends Pen
    assert(method_exists(Marker::class, 'highlight'), 'Marker must have highlight()');
    assert(method_exists(Marker::class, 'write'), 'Marker must inherit write() from Pen');

    // Pencil members
    assert(method_exists(Pencil::class, 'sketch'), 'Pencil must have sketch()');
    assert(method_exists(Pencil::class, 'sharpen'), 'Pencil must have sharpen()');

    // Rock and Banana members (narrowing demos rely on these)
    assert(method_exists(Rock::class, 'crush'), 'Rock must have crush()');
    assert(method_exists(Rock::class, 'weigh'), 'Rock must have weigh()');
    assert(!method_exists(Rock::class, 'peel'), 'Rock must NOT have peel()');
    assert(method_exists(Banana::class, 'peel'), 'Banana must have peel()');
    assert(method_exists(Banana::class, 'weigh'), 'Banana must have weigh()');
    assert(!method_exists(Banana::class, 'crush'), 'Banana must NOT have crush()');

    // ── Array functions preserve types ───────────────────────────────────
    $penArray = [new Pen('red'), new Pen('blue'), new Pen('green')];
    $filtered = array_filter($penArray, fn(Pen $p) => $p->color() === 'blue');
    assert(count($filtered) === 1, 'array_filter must filter correctly');
    assert(reset($filtered) instanceof Pen, 'array_filter must preserve Pen type');

    $vals = array_values($penArray);
    assert($vals[0] instanceof Pen, 'array_values must preserve Pen type');

    $popped = array_pop($penArray);
    assert($popped instanceof Pen, 'array_pop must return Pen');

    $penArray2 = [new Pen('a'), new Pen('b')];
    $cur = current($penArray2);
    assert($cur instanceof Pen, 'current() must return Pen');

    $last = end($penArray2);
    assert($last instanceof Pen, 'end() must return Pen');

    $reduced = array_reduce($penArray2, function(Pen $carry, Pen $item): Pen {
        return $carry;
    }, new Pen('merged'));
    assert($reduced instanceof Pen, 'array_reduce must return type of initial value');

    $sum = array_sum([10, 20, 30]);
    assert(is_int($sum) || is_float($sum), 'array_sum must return int or float');

    $product = array_product([2, 3, 4]);
    assert(is_int($product) || is_float($product), 'array_product must return int or float');

    // ── Match expression types ──────────────────────────────────────────
    $matchResult = match (0) {
        0 => new ElasticProductReviewIndexService(),
        1 => new ElasticBrandIndexService(),
    };
    assert($matchResult instanceof ElasticProductReviewIndexService
        || $matchResult instanceof ElasticBrandIndexService,
        'Match expression must return one of the branch types');
    assert(method_exists($matchResult, 'index'), 'Match result must have shared index() method');

    // ── Ternary expression types ────────────────────────────────────────
    $ternaryResult = true
        ? new ElasticProductReviewIndexService()
        : new ElasticBrandIndexService();
    assert(method_exists($ternaryResult, 'index'), 'Ternary result must have shared index() method');

    // ── Intersection types ──────────────────────────────────────────────
    // Can't instantiate an intersection directly, but we can verify interfaces
    assert(method_exists(Envelope::class, 'seal'), 'Envelope must have seal()');
    assert(interface_exists(Printable::class), 'Printable must be an interface');

    // A parenthesized DNF return type `(Envelope&Printable)|null` really
    // yields an object that satisfies both, so both members are callable.
    $sealed = (new IntersectionDemo())->sealed();
    assert($sealed instanceof Envelope, 'sealed() must return an Envelope');
    assert($sealed instanceof Printable, 'sealed() must return a Printable');

    // ── First-class callable syntax ─────────────────────────────────────
    $fun = makePen(...);
    assert($fun instanceof \Closure, 'makePen(...) must be a Closure');
    $funResult = $fun();
    assert($funResult instanceof Pen, 'makePen(...)() must return Pen');

    $staticCallable = Pen::make(...);
    assert($staticCallable instanceof \Closure, 'Pen::make(...) must be a Closure');
    $staticResult = $staticCallable();
    assert($staticResult instanceof Pen, 'Pen::make(...)() must return Pen');

    $src2 = new ScaffoldingFirstClassCallable();
    $methodCallable = $src2->dispatch(...);
    assert($methodCallable instanceof \Closure, '$obj->method(...) must be a Closure');
    $methodResult = $methodCallable();
    assert($methodResult instanceof Pen, 'dispatch(...)() must return Pen');

    // Immediate invocation: method(...)() returns the method's return type
    $immediateFunc = makePen(...)();
    assert($immediateFunc instanceof Pen, 'makePen(...)() immediate must return Pen');
    $immediateStatic = Pen::make(...)();
    assert($immediateStatic instanceof Pen, 'Pen::make(...)() immediate must return Pen');
    $immediateMethod = $src2->dispatch(...)();
    assert($immediateMethod instanceof Pen, '$obj->dispatch(...)() immediate must return Pen');

    // ── Class alias (use ... as) ────────────────────────────────────────
    $aliasProfile = new Profile($userForProfile);
    assert($aliasProfile instanceof UserProfile, 'Profile alias must be UserProfile');
    assert($aliasProfile instanceof Profile, 'Profile alias instanceof must work');

    // ── HoverOriginsDemo extends Model implements Renderable ────────────
    $hod = new HoverOriginsDemo();
    assert($hod instanceof Model, 'HoverOriginsDemo must extend Model');
    assert($hod instanceof Renderable, 'HoverOriginsDemo must implement Renderable');
    assert(method_exists($hod, 'format'), 'HoverOriginsDemo must have format()');
    assert(method_exists($hod, 'toArray'), 'HoverOriginsDemo must have toArray()');
    assert(method_exists($hod, 'getName'), 'HoverOriginsDemo must inherit getName()');

    // ── Switch statement type tracking ──────────────────────────────────
    $switchType = 'reviews';
    switch ($switchType) {
        case 'reviews':
            $switchService = new ElasticProductReviewIndexService();
            break;
        default:
            $switchService = new ElasticBrandIndexService();
            break;
    }
    assert(method_exists($switchService, 'index'), 'Switch-assigned variable must have index()');

    // ── Spread operator ─────────────────────────────────────────────────
    $spreadSource = [new Pen('a'), new Pen('b')];
    $spread = [...$spreadSource];
    assert($spread[0] instanceof Pen, 'Spread must preserve Pen type');
    assert(count($spread) === 2, 'Spread must preserve array length');

    $pencilSource = [new Pencil()];
    $mixed = [...$spreadSource, ...$pencilSource];
    assert($mixed[0] instanceof Pen || $mixed[0] instanceof Pencil, 'Multi-spread must contain Pen|Pencil');

    // ── Array destructuring ─────────────────────────────────────────────
    $destructSource = [new Pen('x'), new Pen('y')];
    [$dFirst, $dSecond] = $destructSource;
    assert($dFirst instanceof Pen, 'Destructured element must be Pen');
    assert($dSecond instanceof Pen, 'Second destructured element must be Pen');

    // ── Named key destructuring from shape ──────────────────────────────
    $shapeSource = ['pen' => new Pen(), 'pencil' => new Pencil()];
    ['pen' => $dPen, 'pencil' => $dPencil] = $shapeSource;
    assert($dPen instanceof Pen, 'Named destructured pen must be Pen');
    assert($dPencil instanceof Pencil, 'Named destructured pencil must be Pencil');

    // ── Nested destructuring ────────────────────────────────────────────
    /** @var array{string, array{Pen, Pencil}} $nestedDestr */
    $nestedDestr = ['label', [new Pen(), new Pencil()]];
    [$nLabel, [$nPen, $nPencil]] = $nestedDestr;
    assert(is_string($nLabel), 'Nested destructured label must be string');
    assert($nPen instanceof Pen, 'Nested destructured pen must be Pen');
    assert($nPencil instanceof Pencil, 'Nested destructured pencil must be Pencil');

    // ── Foreach destructuring ───────────────────────────────────────────
    /** @var array<int, array{tool: Pen, count: int}> $foreachDestrInv */
    $foreachDestrInv = [['tool' => new Pen(), 'count' => 5]];
    foreach ($foreachDestrInv as ['tool' => $fTool, 'count' => $fCount]) {
        assert($fTool instanceof Pen, 'Foreach destructured tool must be Pen');
        assert(is_int($fCount), 'Foreach destructured count must be int');
    }

    // ── Dynamic (non-literal) key on a shape ────────────────────────────
    $shapeDemo = new ShapeMethodDemo();
    $dynKit = $shapeDemo->getToolKit();
    $dynWhich = 'pen';
    $dynTool = $dynKit[$dynWhich] ?? null;
    assert($dynTool instanceof Pen, 'Dynamic key on shape must yield a shape value');

    $dynSums = [];
    foreach ([1, 2] as $dynId) {
        $dynSums[$dynId] = $shapeDemo->getToolKit();
        assert($dynSums[$dynId]['pen'] instanceof Pen,
            'Dynamic-key write must read back the shape value');
    }

    $dynReport = [];
    $dynCount = 0;
    foreach ([new Pen(), new Pen()] as $dynPen) {
        $dynReport['data'][$dynCount]['tool'] = $dynPen;
        $dynEntry = $dynReport['data'][$dynCount]['tool'];
        assert($dynEntry instanceof Pen, 'Nested dynamic write must read back Pen');
        $dynCount++;
    }

    // ── Ambiguous variables ─────────────────────────────────────────────
    if (rand(0, 1)) {
        $ambiguous = new Lamp();
    } else {
        $ambiguous = new Faucet();
    }
    assert($ambiguous instanceof Lamp || $ambiguous instanceof Faucet,
        'Ambiguous var must be Lamp|Faucet');
    assert(method_exists($ambiguous, 'turnOff'), 'Both Lamp and Faucet have turnOff()');

    // ── Guard clause narrowing ──────────────────────────────────────────
    $guardSubject = pickRockOrBanana();
    if (!$guardSubject instanceof Banana) {
        // would return in real code; just verify type
        assert($guardSubject instanceof Rock, 'Guard: not Banana must be Rock');
    } else {
        assert($guardSubject instanceof Banana, 'Guard: else must be Banana');
        }

        // ── Guard clause: positive instanceof + early return on mixed ────
        // After `if ($x instanceof Y) { return; }`, $x is NOT Y.
        $mixedGuardVal = rand(0, 1) ? new Rock() : 'scalar';
        if ($mixedGuardVal instanceof Banana) {
            // would return in real code
            assert(false, 'Guard: should not reach here (Banana branch)');
        }
        // $mixedGuardVal is NOT Banana after the guard
        if ($mixedGuardVal instanceof Rock) {
            assert(is_string($mixedGuardVal->crush()), 'Guard: mixed narrowed to Rock');
        }

    // ── Null coalesce refinement ────────────────────────────────────────
    $ncA = new Pen() ?? new Marker();
    assert($ncA instanceof Pen, 'Null coalesce: non-nullable LHS must be Pen');

    $ncNullable = rand(0, 1) ? new Pen() : null;
    $ncB = $ncNullable ?? new Marker();
    assert($ncB instanceof Pen || $ncB instanceof Marker,
        'Null coalesce: nullable LHS must be Pen or Marker');

    $ncClone = clone new Pen() ?? new Marker();
    assert($ncClone instanceof Pen, 'Null coalesce: clone LHS must be Pen');

    // ── Ternary narrowing ───────────────────────────────────────────────
    $ternaryThing = pickRockOrBanana();
    $ternaryResult2 = $ternaryThing instanceof Rock ? $ternaryThing->crush() : $ternaryThing->peel();
    assert(is_string($ternaryResult2), 'Ternary narrowed call must return string');

    // ── User::toArray() ─────────────────────────────────────────────────
    $userArr = (new User('Test', 'test@example.com'))->toArray();
    assert(is_array($userArr), 'User::toArray() must return array');

    // ── AstNode (template bounds) ───────────────────────────────────────
    $astNode = new AstNode();
    assert($astNode->getType() === '' || is_string($astNode->getType()), 'AstNode::getType() must return string');
    $children = $astNode->getChildren();
    assert(is_array($children), 'AstNode::getChildren() must return array');

    // ── Pass-by-reference parameter type ────────────────────────────────
    $refPen = null;
    initPen($refPen);
    assert($refPen instanceof Pen, 'initPen(&$pen) must give $pen type Pen');

    $staticPen = null;
    PenFactory::create($staticPen);
    assert($staticPen instanceof Pen, 'PenFactory::create(&$pen) must give $pen type Pen');

    $ctorPen = null;
    new PenBuilder($ctorPen);
    assert($ctorPen instanceof Pen, 'new PenBuilder(&$pen) must give $pen type Pen');

    // ── Interface template inheritance (class-string<T>) ────────────────
    $locator = new ScaffoldingEntityLocator();
    $locatorResult = $locator->find(Pen::class);
    assert($locatorResult instanceof Pen, 'ScaffoldingEntityLocator::find(Pen::class) must return Pen');

    // ── Function-level @template (collect) ──────────────────────────────
    $collectPens = [new Pen()];
    $collected = collect($collectPens);
    assert($collected instanceof FluentCollection, 'collect() must return FluentCollection');
    $firstPen = $collected->first();
    assert($firstPen instanceof Pen, 'collect(Pen[])->first() must return Pen');

    // ── Generic @phpstan-assert narrowing ────────────────────────────────
    $assertObj = new Pen();
    ScaffoldingAssert::assertInstanceOf(Pen::class, $assertObj);
    assert($assertObj instanceof Pen, 'ScaffoldingAssert::assertInstanceOf(Pen::class, $obj) must narrow to Pen');

    // A variable class argument still guarantees the subject is an object.
    $assertCls = Pen::class;
    $assertNode = new Pen();
    ScaffoldingAssert::assertInstanceOf($assertCls, $assertNode);
    assert($assertNode instanceof Pen, 'ScaffoldingAssert::assertInstanceOf($cls, $node) keeps the prior Pen type');

    // ── @param-closure-this scaffolding ──────────────────────────────────
    $ctRoute = new ScaffoldingClosureThisRoute();
    $ctMw = $ctRoute->middleware('auth');
    assert($ctMw instanceof ScaffoldingClosureThisRoute, 'Route::middleware() must return self');
    $ctPfx = $ctRoute->prefix('/api');
    assert($ctPfx instanceof ScaffoldingClosureThisRoute, 'Route::prefix() must return self');

    $ctRouter = new ScaffoldingClosureThisRouter();
    assert(is_string($ctRouter->getDefaultDriver()), 'Router::getDefaultDriver() must return string');
    $ctExt = $ctRouter->extend('redis', function () {});
    assert($ctExt instanceof ScaffoldingClosureThisRouter, 'Router::extend() must return self');

    // ── @mixin generic substitution scaffolding ─────────────────────────
    $mixinBuilder = new ScaffoldingMixinBuilder();
    assert($mixinBuilder->firstOrFail() === null, 'ScaffoldingMixinBuilder::firstOrFail() must return mixed');
    $mixinRelation = new ScaffoldingMixinRelation();
    assert($mixinRelation instanceof ScaffoldingMixinRelation, 'ScaffoldingMixinRelation instantiates');
    $mixinBelongsTo = new ScaffoldingMixinBelongsTo();
    assert($mixinBelongsTo instanceof ScaffoldingMixinRelation, 'ScaffoldingMixinBelongsTo extends ScaffoldingMixinRelation');
    $orderLine = new ScaffoldingOrderLine();
    $productRel = $orderLine->product();
    assert($productRel instanceof ScaffoldingMixinBelongsTo, 'OrderLine::product() must return ScaffoldingMixinBelongsTo');

    // ── @mixin with template parameter ──────────────────────────────────
    $tplMixinNode = new ScaffoldingConcreteAstNode();
    $col = $tplMixinNode->getStartColumn();
    assert(is_int($col), 'ConcreteAstNode (via @mixin TNode bound) getStartColumn() must return int');
    // The tighter member is only on the subclass's narrowed bound, resolved
    // through the @mixin declared on the base class.
    $tplCallableNode = new ScaffoldingConcreteCallableAstNode();
    $count = $tplCallableNode->getParameterCount();
    assert(is_int($count), 'ConcreteCallableAstNode (via tightest @mixin TNode bound) getParameterCount() must return int');

    // ── new $var() with class-string<T> ─────────────────────────────────
    $penFromClassString = ScaffoldingClassStringFactory::create(Pen::class);
    assert($penFromClassString instanceof Pen, 'ClassStringFactory::create(Pen::class) must return Pen');

    // ── Inherited docblock type propagation ─────────────────────────────
    $iHolder = new ScaffoldingConcreteHolder();
    $iHolderPens = $iHolder->getPens();
    assert(is_array($iHolderPens), 'ScaffoldingConcreteHolder::getPens() must return array');
    assert($iHolderPens[0] instanceof Pen, 'ScaffoldingConcreteHolder::getPens()[0] must be Pen');

    $iChild = new ScaffoldingChildHolder();
    $iChildPens = $iChild->getPens();
    assert(is_array($iChildPens), 'ScaffoldingChildHolder::getPens() must return array');
    assert($iChildPens[0] instanceof Pen, 'ScaffoldingChildHolder::getPens()[0] must be Pen');

    $iDeep = new ScaffoldingDeepChild();
    $iDeepPens = $iDeep->getPens();
    assert(is_array($iDeepPens), 'ScaffoldingDeepChild::getPens() must return array');
    assert($iDeepPens[0] instanceof Pen, 'ScaffoldingDeepChild::getPens()[0] must be Pen');

    $iCat = new ScaffoldingCatStore();
    $iCatAnimals = $iCat->getAnimals();
    assert(is_array($iCatAnimals), 'ScaffoldingCatStore::getAnimals() must return array');
    assert($iCatAnimals[0] instanceof Pencil, 'ScaffoldingCatStore::getAnimals()[0] must be Pencil');

    $iBox = new ScaffoldingPenBox();
    $iBoxPens = $iBox->getPens();
    assert(is_array($iBoxPens), 'ScaffoldingPenBox::getPens() must return array');
    assert($iBoxPens[0] instanceof Pen, 'ScaffoldingPenBox::getPens()[0] must be Pen');

    // ── Loop-carried assignment ─────────────────────────────────────────
    $lcPens = [new Pen('a'), new Pen('b')];
    $lcPrev = null;
    foreach ($lcPens as $lcPen) {
        if ($lcPrev !== null) {
            assert($lcPrev instanceof Pen, 'Loop-carried $lcPrev must be Pen on second iteration');
        }
        $lcPrev = $lcPen;
    }
    assert($lcPrev instanceof Pen, '$lcPrev must be Pen after foreach');

    $lcLast = null;
    $lcIter = 0;
    while ($lcIter < 2) {
        if ($lcLast !== null) {
            assert($lcLast instanceof Response, 'Loop-carried $lcLast must be Response');
        }
        $lcLast = new Response(200, 'ok');
        $lcIter++;
    }
    assert($lcLast instanceof Response, '$lcLast must be Response after while');

    // ── Constant type inference ─────────────────────────────────────────
    assert(ConstantTypeDemo::TIMEOUT === 30, 'ConstantTypeDemo::TIMEOUT must be 30');
    assert(ConstantTypeDemo::NAME === 'app', 'ConstantTypeDemo::NAME must be "app"');
    assert(ConstantTypeDemo::RATE === 3.14, 'ConstantTypeDemo::RATE must be 3.14');
    assert(ConstantTypeDemo::ENABLED === true, 'ConstantTypeDemo::ENABLED must be true');
    assert(CT_ALLOWED_HOSTS === ['localhost', '127.0.0.1'], 'CT_ALLOWED_HOSTS must match');
    assert(CT_APP_VERSION === '2.0.0', 'CT_APP_VERSION must be "2.0.0"');

    // ── Variadic foreach ────────────────────────────────────────────────
    $vfDemo = new VariadicForeachDemo();
    $vfPens = [new Pen('a'), new Pen('b')];
    // demo() accepts Pen ...$pens — foreach inside should see Pen elements
    $vfDemo->demo(...$vfPens);
    foreach ($vfPens as $vfPen) {
        assert($vfPen instanceof Pen, 'Variadic Pen element must be Pen');
    }
    $vfTools = [new Pen('x'), new Pencil()];
    foreach ($vfTools as $vfTool) {
        assert(
            $vfTool instanceof Pen || $vfTool instanceof Pencil,
            'Variadic union element must be Pen or Pencil'
        );
    }

    // ── Type guard narrowing ────────────────────────────────────────────
    /** @var list<Pen> $tgPens */
    $tgPens = [new Pen('a'), new Pen('b')];
    /** @var null|list<Pen>|Pen $tgInput */
    $tgInput = $tgPens;
    if (is_array($tgInput)) {
        foreach ($tgInput as $tgPen) {
            assert($tgPen instanceof Pen, 'is_array() narrowed foreach element must be Pen');
        }
    }
    $tgSingle = new Pen('solo');
    /** @var list<Pen>|Pen $tgMixed */
    $tgMixed = $tgSingle;
    if (!is_array($tgMixed)) {
        assert($tgMixed instanceof Pen, 'Else branch of is_array() must be Pen');
    }

    // ── Foreach array shape elements ────────────────────────────────────
    /** @var array<int, array{tool: Pen, count: int}> $fasInventory */
    $fasInventory = [['tool' => new Pen('red'), 'count' => 3]];
    foreach ($fasInventory as $fasEntry) {
        assert($fasEntry['tool'] instanceof Pen, 'Foreach over array shape must resolve key type');
    }

    // ── Loop array build (variable-key assignment) ──────────────────────
    $labPens = [new Pen('red'), new Pen('blue')];
    $labIndexed = [];
    foreach ($labPens as $labPen) {
        $labKey = $labPen->color();
        $labIndexed[$labKey] = $labPen;
    }
    assert($labIndexed['red'] instanceof Pen, 'Variable-key array element must be Pen');
    foreach ($labIndexed as $labItem) {
        assert($labItem instanceof Pen, 'Foreach over variable-key array must yield Pen');
    }
    $labFound = $labIndexed['blue'] ?? null;
    assert($labFound instanceof Pen, 'Null-coalesce on variable-key array must resolve to Pen');

    // ── Conditional shape key addition ──────────────────────────────────
    $cskOptions = ['name' => 'default'];
    $cskPen = new Pen('blue');
    $cskOptions['tool'] = $cskPen;
    assert($cskOptions['tool'] instanceof Pen, 'Conditional shape key must resolve to Pen');

    // ── Conditional loop shape (keyed assignment in if/else) ────────────
    $shapePens = [new Pen('red'), new Pen('blue'), new Pen('red')];
    $shapeGrouped = [];
    foreach ($shapePens as $shapePen) {
        $shapeKey = $shapePen->color();
        if (array_key_exists($shapeKey, $shapeGrouped)) {
            $shapeGrouped[$shapeKey]['count']++;
        } else {
            $shapeGrouped[$shapeKey] = [
                'tool'  => $shapePen,
                'count' => 1,
            ];
        }
    }
    foreach ($shapeGrouped as $shapeEntry) {
        assert($shapeEntry['tool'] instanceof Pen, 'Shape key from conditional loop must resolve to Pen');
    }

    // ── Untyped property inference from constructor ─────────────────────
    $untypedDemo = new UntypedPropertyInferenceDemo();
    // The scaffolding repo's findById() returns Pen, so we can verify
    // that the inferred type propagates through the property chain.
    $repoRef = new ScaffoldingUntypedRepo();
    $found = $repoRef->findById(1);
    assert($found instanceof Pen, 'ScaffoldingUntypedRepo::findById() must return Pen');

    // ── Deep variable chain ────────────────────────────────────────────
    $chainBrush = new Brush();
    $chainCanvas = $chainBrush->getCanvas();
    assert($chainCanvas instanceof Canvas, 'Brush::getCanvas() must return Canvas');
    $chainEasel = $chainCanvas->easel;
    assert($chainEasel instanceof Easel, 'Canvas::$easel must be Easel');
    $chainMaterial = $chainEasel->material;
    assert(is_string($chainMaterial), 'Easel::$material must be string');
    $chainBack = $chainCanvas->getBrush();
    assert($chainBack instanceof Brush, 'Canvas::getBrush() must return Brush');

    // ── Closure scope inference ────────────────────────────────────────
    $scopePens = [new Pen()];
    $scopeWorker = function () use ($scopePens): void {
        foreach ($scopePens as $sp) {
            assert($sp instanceof Pen, 'Captured $pens element must be Pen');
        }
    };
    $scopeWorker();

    // ── Global keyword ─────────────────────────────────────────────────
    global $globalPen;
    assert($globalPen instanceof Pen, '$globalPen must be Pen at top level');
    globalKeywordDemo();

    // ── Built-in generic collections ────────────────────────────────────
    $demo = new BuiltinGenericCollectionDemo();
    $pen = $demo->getPens()->current();
    assert($pen instanceof Pen, 'ArrayIterator<int, Pen>::current() must return Pen');

    // ── SimpleXMLElement iteration (Iterator without generics) ──────────
    $xmlDemo = new SimpleXmlIterationDemo();
    $xmlChild = $xmlDemo->firstChild();
    assert($xmlChild instanceof \SimpleXMLElement, 'SimpleXMLElement::children() foreach element must be SimpleXMLElement');

    // ── SPL wrapper iterators ───────────────────────────────────────────
    $filter = new PhpFileFilter(new \ArrayIterator([new \SplFileInfo(__FILE__)]));
    foreach ($filter as $splFile) {
        assert($splFile instanceof \SplFileInfo, 'FilterIterator<_, SplFileInfo, _> foreach element must be SplFileInfo');
    }
    foreach (new \DirectoryIterator(__DIR__) as $dirEntry) {
        assert($dirEntry instanceof \DirectoryIterator, 'DirectoryIterator foreach element must be DirectoryIterator');
        break;
    }

    echo "All assertions passed.\n";
}

runDemoAssertions();