diff --git a/.changeset/27587-objectui-skill-teaches-cel-predicates.md b/.changeset/27587-objectui-skill-teaches-cel-predicates.md
new file mode 100644
index 00000000000..1da68cc36cd
--- /dev/null
+++ b/.changeset/27587-objectui-skill-teaches-cel-predicates.md
@@ -0,0 +1,12 @@
+---
+'@objectstack/skills': patch
+---
+
+docs(skills): objectui teaches CEL for a bare-string predicate, with a FROM → TO list for the JavaScript spellings
+
+Clause-②: no
+Metadata-protocol: none
+
+- **Before.** `skills/objectui` taught bare predicates in the legacy JavaScript grammar: `"hidden": "data.status === 'draft'"` in `rules/protocol.md`, `data.status === 'active'` and `data.status !== 'active'` in `guides/schema-expressions.md`, and an operator list (`===`, `!==`, `.includes()`, `.length`) that read as condition syntax. Since #27584 the console reads a bare string in a predicate key as CEL, as the spec defines it and the server reads it, so an agent following the skill wrote a gate that faulted and hid the node.
+- **Now.** Every bare-predicate example is CEL. The guide says a bare condition string is CEL on `@objectstack/formula` and that the operator list is the `${…}` template grammar only, and it gives a FROM → TO list measured on the console's evaluator: `===` / `!==` → `==` / `!=`; `list.includes(x)` → `x in list`, `s.includes('x')` → `s.contains('x')`; `list.length` → `size(list)`; a `data.*` key the scope may lack → `has(data.x) && …`, because CEL faults on a missing key. The row-predicate bullet says only a `${…}` condition still reads on the legacy engine. Eval 2 in `evals/schema-expressions.json` hands over a JS-syntax predicate and expects the CEL rewrite.
+- No schema, key or behaviour changes.
diff --git a/skills/objectui/evals/schema-expressions.json b/skills/objectui/evals/schema-expressions.json
index a249e16c61e..d998fab476b 100644
--- a/skills/objectui/evals/schema-expressions.json
+++ b/skills/objectui/evals/schema-expressions.json
@@ -20,12 +20,13 @@
     },
     {
       "id": 2,
-      "prompt": "I need to make a button visible only to admin users AND only when the record status is 'active'. Also, the button should show the record owner's name. Show me the correct schema.",
-      "expected_output": "Produces a schema with combined visible/hidden expression using && operator, and does not put the owner name in props.label — that envelope is evaluated and then discarded. The name is resolved in the host, or carried on a text node's content.",
+      "prompt": "My button should show only to admins AND only while the status is 'active', with the owner's name on it. I wrote \"visibleWhen\": \"data.role === 'admin' && data.status === 'active'\" and it never shows. Fix the schema.",
+      "expected_output": "Says a bare predicate is CEL, so === faults and hides the node; rewrites it with == and &&. The owner name goes on a text node's content, not props.label.",
       "files": [],
       "assertions": {
         "must_contain": [
-          "visible",
+          "CEL",
+          "status == 'active'",
           "&&",
           "${"
         ],
diff --git a/skills/objectui/guides/schema-expressions.md b/skills/objectui/guides/schema-expressions.md
index 74190d7c1d2..03088767824 100644
--- a/skills/objectui/guides/schema-expressions.md
+++ b/skills/objectui/guides/schema-expressions.md
@@ -6,10 +6,8 @@ Writing and debugging dynamic expressions in ObjectUI schemas. The expression sy
 
 ObjectUI uses a two-tier expression evaluator:
 
-1. **Template expressions** — strings containing `${...}` placeholders: `"Hello ${user.name}"`
-2. **Condition expressions** — raw boolean expressions without wrappers: `data.status === 'active'`
-
-Both are parsed by a **recursive-descent parser** (no `eval()`, no `new Function()`). This means expressions are CSP-safe and work under strict Content Security Policy headers.
+1. **Template expressions** — strings containing `${...}` placeholders: `"Hello ${user.name}"`, parsed by a **recursive-descent parser** (no `eval()`, no `new Function()`), so CSP-safe.
+2. **Condition expressions** — a bare string in a predicate key: `data.status == 'active'`. It is **CEL**, evaluated by `@objectstack/formula`, as on the server.
 
 Key files (for reference, not for editing):
 - `packages/core/src/evaluator/ExpressionEvaluator.ts` — main entry point
@@ -55,11 +53,6 @@ this rule. The four cases that decide most schemas:
 { "type": "text", "content": "${data.customer.name}" }
 ```
 
-`title` / `label` / `value` / `description` are template-evaluated on the types
-that declare them -- `statistic` (`label` / `value` / `description`), `card`
-(`title` / `description`), `button` (`label`) -- and read raw everywhere else.
-The set is closed and declared in `@objectstack/spec`.
-
 ## Template expression syntax (`${}`)
 
 ### Basic property access
@@ -79,6 +72,9 @@ ${!isLocked}                    → boolean negation
 ```
 
 ### Supported operators (full list)
+
+The `${…}` grammar only. A bare condition string is CEL — see "Condition fields".
+
 - Arithmetic: `+`, `-`, `*`, `/`, `%`
 - Comparison: `>`, `<`, `>=`, `<=`, `==`, `===`, `!=`, `!==`
 - Logical: `&&`, `||`, `!`
@@ -237,7 +233,7 @@ name, so calls are case-insensitive.
 ### Syntax options
 
 The node-level condition keys are `visibleWhen` (show), `hidden` and
-`disabled`. Each takes a boolean, a `${}` template, or a raw expression:
+`disabled`. Each takes a boolean, a `${}` template, or a bare CEL string:
 
 <!-- os:check -->
 ```jsonc
@@ -251,9 +247,19 @@ The node-level condition keys are `visibleWhen` (show), `hidden` and
 
 <!-- os:check -->
 ```jsonc
-{ "hidden": "data.status !== 'active'" } // raw expression (no ${} needed)
+{ "hidden": "data.status != 'active'" } // bare string = CEL (no ${} needed)
 ```
 
+A JS-only spelling in a bare string faults: a visibility gate hides the node,
+`disabled` disables. FROM → TO:
+
+- `a === b` / `a !== b` → `a == b` / `a != b`
+- `list.includes(x)` → `x in list`; `s.includes('x')` → `s.contains('x')`
+- `list.length` → `size(list)`
+- a `data.*` key the scope may lack (`data.x == 1`, `!data.x`, `?.`, `??`) →
+  `has(data.x) && data.x == 1`, `!has(data.x) || !data.x`: CEL faults on a
+  missing key
+
 `visibleOn` / `hiddenOn` / `disabledOn` are retired and refused by name —
 rename to `visibleWhen` / `hidden` / `disabled`; the value is unchanged.
 
@@ -292,10 +298,8 @@ rename to `visibleWhen` / `hidden` / `disabled`; the value is unchanged.
 ## Field-level conditional rules (`visibleWhen` / `readonlyWhen` / `requiredWhen`)
 
 These live on the **object's field metadata**, are written in CEL, and are
-evaluated by `@objectstack/formula` -- a different tier from the node-level
-conditions above, which are schema/widget-level and run on the recursive-descent
-`SafeExpressionParser`. **How to author them is the `objectstack-data` skill's
-job**, under "Conditional Field Rules": the predicate scope, the client-only vs
+evaluated by `@objectstack/formula`. **How to author them is the
+`objectstack-data` skill's job**, under "Conditional Field Rules": the predicate scope, the client-only vs
 client-and-server enforcement split, the invariant-vs-transition-gate choice,
 and the protocol-17 removal of the `conditionalRequired` alias are all there.
 Author them in the canonical tagged-template form that skill teaches
@@ -332,9 +336,8 @@ Three renderer-side facts that live nowhere else:
   operator, value }` form and the `{ expression: "${…}" }` template form are
   retired, refused at the schema door by name with the respelling. A STORED
   legacy rule still renders through the shared evaluator (a compatibility read,
-  not an authoring form); a `condition` in legacy-only syntax (`${…}`, `===`,
-  `.includes()`) still routes to the old engine with a one-time deprecation
-  warning -- write CEL.
+  not an authoring form); only a `${…}` `condition` still routes to the old
+  engine. `===` or `.includes()` faults on CEL. Both warn once -- write CEL.
 - **`data.*` is the trap in a row predicate.** A row predicate binds ONE root,
   `record.*`; a bare `status` or `data.status` is retired there and faults on
   the runtime engine (`Unknown variable`), under each surface's existing error
@@ -637,6 +640,6 @@ When an expression isn't working:
 1. **Which key is it on, and does that type declare the key?** `content` and the predicate keys are evaluated and read on every type. `title` / `label` / `value` / `description` are evaluated **only on the types that declare them** — `statistic` (`label` / `value` / `description`), `card` (`title` / `description`), `button` (`label`) — and read raw everywhere else, including on a namespaced spelling such as `ui:statistic`. A `${...}` inside a `props` envelope is evaluated and then discarded. (A `properties` envelope is the one that is evaluated *and* hoisted onto the node — see [`rules/protocol.md`](../rules/protocol.md) for why that is recorded, not recommended.)
 2. Is the `${}` syntax correct? Check for unmatched braces.
 3. Is the data actually available in scope? Check what the host published on `PredicateScopeProvider` — ⛔ not `SchemaRendererProvider`'s `dataSource`, which publishes no expression root.
-4. For conditions: `visibleWhen` / `hidden` / `disabled` take a raw expression or a `${}` template; the `On` spellings are refused.
+4. For conditions: `visibleWhen` / `hidden` / `disabled` take a bare CEL string or a `${}` template.
 5. Does the expression use a blocked pattern? Check for constructors, `eval`, `window`, etc.
 6. Is type coercion causing issues? `${0 && "yes"}` returns `0`, not `false`.
diff --git a/skills/objectui/rules/protocol.md b/skills/objectui/rules/protocol.md
index 45c9f45cd36..1f4a601edb1 100644
--- a/skills/objectui/rules/protocol.md
+++ b/skills/objectui/rules/protocol.md
@@ -13,8 +13,8 @@ value must clear before it reaches the screen.
 | Field | Evaluation Type | Return Type | Example |
 |---|---|---|---|
 | `content` | Template (`${}`) | string | `"content": "Total: ${data.total}"` |
-| `visibleWhen` | Condition | boolean | `"visibleWhen": "data.permissions.canView"` (raw expression, no `${}`) |
-| `hidden` | Condition | boolean | `"hidden": "data.status === 'draft'"` |
+| `visibleWhen` | Condition | boolean | `"visibleWhen": "data.permissions.canView"` (bare string = CEL) |
+| `hidden` | Condition | boolean | `"hidden": "data.status == 'draft'"` |
 | `visible` | Condition | boolean | `"visible": "${data.isActive}"` |
 | `disabled` | Condition | boolean | `"disabled": "!data.hasPermission"` |
 | `title` / `label` / `value` / `description` | Template (`${}`) | Preserves original type | **Only on the component types the spec declares** — see "Rule: Bindable Text Keys" below. `"value": "${data.total}"` on a `statistic` renders the number. |