Fix/ternary precedence codegen

packages/core/src/codegen-expression.ts

@@ -639,7 +639,7 @@ export function needsBinaryParens(child: ValueIR, parentOp: string, side: 'left'
 }
 
 function needsParens(child: ValueIR, parentOp: string, side: 'left' | 'right'): boolean {
-  if (child.kind === 'typeAssert') return true;
+  if (child.kind === 'typeAssert' || child.kind === 'conditional') return true;
   return needsBinaryParens(child, parentOp, side);
 }
 

packages/python/src/codegen-body-python.ts

@@ -2112,8 +2112,10 @@ function emitPyExprCtx(node: ValueIR, ctx: BodyEmitContext): string {
       const lowered = lowerChain(node, ctx);
       return wrapGuardIfAny(lowered, ctx);
     }
-    case 'await':
-      return `await ${emitPyExprCtx(node.argument, ctx)}`;
+    case 'await': {
+      const arg = emitPyExprCtx(node.argument, ctx);
+      return `await ${needsLowPrecedenceOperandParens(node.argument) ? `(${arg})` : arg}`;
+    }
     case 'new': {
       // Host Error mapping (spec §1): `new Error(args)` → `Exception(args)` on
       // Python, since `raise Error(...)` / `isinstance(x, Error)` would
@@ -2414,8 +2416,14 @@ function emitPyExprCtx(node: ValueIR, ctx: BodyEmitContext): string {
 
       const forceLeft = needsComparisonChainParens(node.left, node.op);
       const forceRight = needsComparisonChainParens(node.right, node.op);
-      const lp = forceLeft || needsBinaryParens(node.left, node.op, 'left') ? `(${left})` : left;
-      const rp = forceRight || needsBinaryParens(node.right, node.op, 'right') ? `(${right})` : right;
+      const lp =
+        forceLeft || needsLowPrecedenceOperandParens(node.left) || needsBinaryParens(node.left, node.op, 'left')
+          ? `(${left})`
+          : left;
+      const rp =
+        forceRight || needsLowPrecedenceOperandParens(node.right) || needsBinaryParens(node.right, node.op, 'right')
+          ? `(${right})`
+          : right;
       const op = mapBinaryOpToPython(node.op);
       return `${lp} ${op} ${rp}`;
     }
@@ -3225,7 +3233,13 @@ function lowerChain(node: ChainNode, ctx: BodyEmitContext): GuardedExpr {
   const inner: GuardedExpr =
     callee.kind === 'member' || callee.kind === 'call' || callee.kind === 'index'
       ? lowerChain(callee, ctx)
-      : { guard: null, expr: emitPyExprCtx(callee, ctx) };
+      : {
+          guard: null,
+          expr: (() => {
+            const emitted = emitPyExprCtx(callee, ctx);
+            return needsLowPrecedenceOperandParens(callee) ? `(${emitted})` : emitted;
+          })(),
+        };
   const args = node.args.map((a) => emitPyExprCtx(a, ctx)).join(', ');
   return { guard: inner.guard, expr: `${inner.expr}(${args})`, lambdaBind: inner.lambdaBind };
 }
@@ -3904,6 +3918,15 @@ function needsWalrusOperandParens(child: ValueIR): boolean {
   return child.kind === 'conditional' || child.kind === 'lambda';
 }
 
+/** Low-precedence operand positions (`a <op> b`, `await x`, `<callee>(...)`)
+ *  must wrap a conditional child so the surrounding operator/call binds to the
+ *  whole operand instead of one ternary arm. */
+function needsLowPrecedenceOperandParens(child: ValueIR): boolean {
+  let node = child;
+  while (node.kind === 'typeAssert' || node.kind === 'nonNull') node = node.expression;
+  return node.kind === 'conditional';
+}
+
 /** S5 review fix — run `fn` with `ctx.banWalrus` set (save/restore), for
  *  emitting an operand that will be interpolated into a comprehension/
  *  generator ITERABLE position, where CPython rejects `:=` outright (see

packages/python/tests/ternary-precedence-codegen.test.ts

@@ -0,0 +1,86 @@
+/** TERNARY-PRECEDENCE codegen fix — the discriminating RED-at-base oracle.
+ *
+ *  BUG (confirmed systemic, agon codex audit 2026-06-16 + verified empirically on both
+ *  legs): KERN's expression emitter drops the parentheses a `conditional` operand needs
+ *  when it sits under a higher-precedence operator. `?:` (TS) / `... if ... else ...`
+ *  (Python) bind LOOSER than `*`/`await`/call, so an unwrapped conditional operand
+ *  silently re-associates — `(true ? 2 : 3) * 5` compiles to `true ? 2 : 3 * 5` (= 2,
+ *  not 10). It also breaks TS↔Python byte-parity (the Python call-callee + await cases
+ *  emit unwrapped while TS wraps).
+ *
+ *  ROOT CAUSE: ad-hoc parenthesization instead of one precedence-aware "subexpression
+ *  operand" policy. TS emitter = `packages/core/src/codegen-expression.ts`; Python =
+ *  `packages/python/src/codegen-body-python.ts`. The fix must wrap a `conditional`
+ *  child in EVERY low-precedence operand position on BOTH legs — and must NOT
+ *  over-wrap (the guards below pin already-correct output so a "wrap everything" cheat
+ *  fails).
+ *
+ *  Python note: `+` lowers to `__kern_add(...)` (call-delimited, inherently safe), so
+ *  these fixtures use `*` (raw infix on BOTH legs) where the bug actually bites. */
+
+import { emitExpression, parseExpression } from '@kernlang/core';
+import { emitPyExpression } from '../src/codegen-body-python.js';
+
+const ts = (src: string): string => emitExpression(parseExpression(src));
+const py = (src: string): string => emitPyExpression(parseExpression(src));
+
+// ── RED at base — a `conditional` operand under a tighter operator must be wrapped ──
+describe('ternary-precedence — conditional operand is parenthesized (currently RED)', () => {
+  // #1 generic infix (binary `*`) — WRONG on BOTH legs at base.
+  test('(ternary) * x — left operand, both legs', () => {
+    expect(ts('(true ? 2 : 3) * 5')).toBe('(true ? 2 : 3) * 5');
+    expect(py('(true ? 2 : 3) * 5')).toBe('(2 if _kern_truthy(True) else 3) * 5');
+  });
+  test('x * (ternary) — right operand, both legs', () => {
+    expect(ts('5 * (false ? 2 : 3)')).toBe('5 * (false ? 2 : 3)');
+    expect(py('5 * (false ? 2 : 3)')).toBe('5 * (2 if _kern_truthy(False) else 3)');
+  });
+  // #2 call callee — WRONG on Python (TS already wraps → also a parity divergence).
+  test('(ternary)(x) — call callee, Python', () => {
+    expect(py('(ok ? f : g)(x)')).toBe('(f if _kern_truthy(ok) else g)(x)');
+  });
+  // #3 await operand — WRONG on Python.
+  test('await (ternary) — Python', () => {
+    expect(py('await (ok ? a() : b())')).toBe('await (a() if _kern_truthy(ok) else b())');
+  });
+});
+
+// ── GREEN guards — pin already-correct output so the fix can't OVER-wrap / regress ──
+describe('ternary-precedence — guards (must stay byte-identical, no spurious parens)', () => {
+  test('TS call callee + await already wrap correctly — must not break', () => {
+    expect(ts('(ok ? f : g)(x)')).toBe('(ok ? f : g)(x)');
+    expect(ts('await (ok ? a() : b())')).toBe('await (ok ? a() : b())');
+  });
+  test('member receiver of a ternary is wrapped on both legs — must stay', () => {
+    expect(ts('(a ? b : c).d')).toBe('(a ? b : c).d');
+    expect(py('(a ? b : c).d')).toBe('(b if _kern_truthy(a) else c).d');
+  });
+  test('plain binary chains gain NO spurious parentheses', () => {
+    expect(ts('2 * 3 + 4')).toBe('2 * 3 + 4');
+    expect(py('2 * 3 + 4')).toBe('__kern_add(2 * 3, 4)');
+    expect(ts('2 * 5')).toBe('2 * 5');
+    expect(py('a + b')).toBe('__kern_add(a, b)');
+  });
+});
+
+// ── TRANSPARENT-WRAPPER blindness (D1) — Python ERASES `as T` / `!`, so a wrapped
+// conditional becomes a BARE conditional in a tight position. The operand predicate must
+// peel transparent wrappers (typeAssert/nonNull) and test the INNER kind. TS keeps the
+// wrapper (`(x as T)` self-parenthesizes) so TS is already correct — this is a Python-only
+// fix AND a TS↔Python byte-divergence until closed. (The recurring wrapper-bypass class.)
+describe('ternary-precedence — transparent-wrapped conditional operand (currently RED, Python)', () => {
+  test('(ternary as T) under a binary op — Python wraps the erased conditional', () => {
+    expect(py('((true ? 2 : 3) as any) * 5')).toBe('(2 if _kern_truthy(True) else 3) * 5');
+    // TS guard: already correct (keeps the cast, wraps the whole operand) — must not regress.
+    expect(ts('((true ? 2 : 3) as any) * 5')).toBe('((true ? 2 : 3) as any) * 5');
+  });
+  test('(ternary as T) as a call callee — Python', () => {
+    expect(py('((ok ? f : g) as any)(x)')).toBe('(f if _kern_truthy(ok) else g)(x)');
+  });
+  test('await (ternary as T) — Python', () => {
+    expect(py('await ((ok ? a() : b()) as any)')).toBe('await (a() if _kern_truthy(ok) else b())');
+  });
+  test('member object of a wrapped ternary is already wrapped — must stay (guard)', () => {
+    expect(py('((a ? b : c) as any).d')).toBe('(b if _kern_truthy(a) else c).d');
+  });
+});