diff --git a/.changeset/prose-example-gate-covers-docs.md b/.changeset/prose-example-gate-covers-docs.md
new file mode 100644
index 0000000000..792fd1b152
--- /dev/null
+++ b/.changeset/prose-example-gate-covers-docs.md
@@ -0,0 +1,47 @@
+---
+"@objectstack/spec": patch
+---
+
+feat(spec): the example type-check gate now covers `content/docs`, not just `skills/`
+
+`check:skill-examples` compiles the TypeScript in prose against the built spec, so
+an example that stops compiling fails CI instead of quietly teaching code that no
+longer works. It does its job — it caught the broken `defineTool` example when
+`tool.requiresConfirmation` was removed (#3715).
+
+But it only ever walked `skills/`:
+
+| Tree | files with `ts` blocks | compiled |
+|---|---|---|
+| `skills/` | 9 | **9** |
+| `content/docs/` (hand-written) | 124 | **0** |
+
+The identical break in a docs page would have shipped. Docs examples are copied
+verbatim by humans and AI exactly like skill examples, so a gate covering a
+fraction of the surface it appears to cover reads as coverage — the same shape as
+the stale-evidence and orphan-proof warnings fixed in #3857 / #3868.
+
+The walker is now a `SOURCE_ROOTS` list, and this lands the first batch: **164
+docs blocks across 63 pages, taking the gate from 32 to 196 checked examples**.
+`content/docs/references/` is excluded — `build-docs.ts` regenerates it from the
+schemas, so it cannot drift independently of its source.
+
+**The marker is now per-format.** MDX has no HTML comments: `<!-- os:check -->` in
+a `.mdx` fails the fumadocs build outright — *"Unexpected character `!`… to create
+a comment in MDX, use `{/* text */}`"*. Caught by building the docs site, after
+the first attempt broke 60+ pages. `skills/**/*.md` keeps `<!-- os:check -->`;
+`content/docs/**/*.mdx` uses `{/* os:check */}`. Both spellings are recognised for
+**orphan** detection, so a wrong-format marker fails loudly rather than silently
+checking nothing — the existing guard's philosophy, extended to the new failure
+mode this change introduces.
+
+The batch was measured rather than guessed: marking all 780 docs blocks and
+compiling showed which are self-contained. One subtlety worth recording — a block
+that "passes" inside a 780-file program can be leaning on globals declared by
+*other* blocks (a file with no import/export is a global script), so the set was
+converged by recompiling and dropping newly-failing blocks until green. 164 stand
+on their own.
+
+The remaining blocks are mostly fragments (a `columns: [...]` subtree), which the
+gate's opt-in design already anticipates. Whether any are genuine rot is worth a
+follow-up now that the machinery reaches them.
diff --git a/content/docs/ai/actions-as-tools.mdx b/content/docs/ai/actions-as-tools.mdx
index 4fe63247ea..1396e2ae9e 100644
--- a/content/docs/ai/actions-as-tools.mdx
+++ b/content/docs/ai/actions-as-tools.mdx
@@ -70,6 +70,7 @@ Add an optional `ai:` block to give the model a precise, LLM-facing description
 spec; `list_actions` surfaces `ai.description` to the model, falling back to the
 UI `label` when it is absent.
 
+{/* os:check */}
 ```typescript
 export const triageCaseAction = {
   name: 'triage_case',
diff --git a/content/docs/ai/agents.mdx b/content/docs/ai/agents.mdx
index e1ce193058..916420c167 100644
--- a/content/docs/ai/agents.mdx
+++ b/content/docs/ai/agents.mdx
@@ -167,6 +167,7 @@ point at, and reach it through `@objectstack/mcp` (BYO-AI).
 
 ## Sales Assistant Agent
 
+{/* os:check */}
 ```typescript
 import { defineAgent } from '@objectstack/spec/ai';
 
diff --git a/content/docs/api/environment-routing.mdx b/content/docs/api/environment-routing.mdx
index f79fddeab1..86c29b7f4d 100644
--- a/content/docs/api/environment-routing.mdx
+++ b/content/docs/api/environment-routing.mdx
@@ -24,6 +24,7 @@ depending on request context.
 
 Enable scoped route registration in `objectstack.config.ts`:
 
+{/* os:check */}
 ```typescript
 import { defineStack } from '@objectstack/spec';
 
diff --git a/content/docs/api/error-handling-client.mdx b/content/docs/api/error-handling-client.mdx
index b406d64fa6..bfd760c344 100644
--- a/content/docs/api/error-handling-client.mdx
+++ b/content/docs/api/error-handling-client.mdx
@@ -17,6 +17,7 @@ This guide covers best practices for handling ObjectStack API errors in client a
 
 Every error response from ObjectStack follows this shape:
 
+{/* os:check */}
 ```typescript
 interface ErrorResponse {
   success: false;        // Always false for error responses
@@ -56,6 +57,7 @@ Error `code` values are lowercase snake_case (`validation_error`, `permission_de
 
 Create a typed error parser to extract structured information from API responses:
 
+{/* os:check */}
 ```typescript
 import type { ErrorResponse } from '@objectstack/spec/api';
 
diff --git a/content/docs/api/error-handling-server.mdx b/content/docs/api/error-handling-server.mdx
index e7d784462d..69702d8f5b 100644
--- a/content/docs/api/error-handling-server.mdx
+++ b/content/docs/api/error-handling-server.mdx
@@ -23,6 +23,7 @@ lowercase snake_case members of `StandardErrorCode` (see
 `@objectstack/spec/api`), e.g. `validation_error`, `resource_conflict`,
 `permission_denied`.
 
+{/* os:check */}
 ```typescript
 import type { ErrorResponse, StandardErrorCode } from '@objectstack/spec/api';
 
@@ -289,6 +290,7 @@ export const EnrichTaskWithAI: Hook = {
 
 Prevent cascading failures when an external service is down:
 
+{/* os:check */}
 ```typescript
 class CircuitBreaker {
   private failures = 0;
diff --git a/content/docs/automation/flows.mdx b/content/docs/automation/flows.mdx
index 2d9f53de66..3576a31883 100644
--- a/content/docs/automation/flows.mdx
+++ b/content/docs/automation/flows.mdx
@@ -9,6 +9,7 @@ A **Flow** is a visual automation that orchestrates business logic through conne
 
 ## Basic Structure
 
+{/* os:check */}
 ```typescript
 const approvalFlow = {
   name: 'order_approval',
@@ -564,6 +565,7 @@ Edges connect nodes and define the execution path:
 
 Flows use variables to pass data between nodes and to/from callers:
 
+{/* os:check */}
 ```typescript
 variables: [
   { name: 'input_id', type: 'text', isInput: true, isOutput: false },
@@ -738,6 +740,7 @@ is retired; model the same logic as a Flow.
 
 ### Record-change flow
 
+{/* os:check */}
 ```typescript
 import type { Flow } from '@objectstack/spec/automation';
 
diff --git a/content/docs/automation/index.mdx b/content/docs/automation/index.mdx
index acae7f5e64..25e64dd4a4 100644
--- a/content/docs/automation/index.mdx
+++ b/content/docs/automation/index.mdx
@@ -9,6 +9,7 @@ Automation is ObjectStack's process engine: you attach business logic to the dat
 
 The smallest useful automation is a hook (from the CRM example app):
 
+{/* os:check */}
 ```typescript
 import type { Hook, HookContext } from '@objectstack/spec/data';
 
diff --git a/content/docs/automation/workflows.mdx b/content/docs/automation/workflows.mdx
index c4ea232e64..c8fc92f37b 100644
--- a/content/docs/automation/workflows.mdx
+++ b/content/docs/automation/workflows.mdx
@@ -21,6 +21,7 @@ This page keeps the historical route but documents the current split.
 Use Flow when something should happen after a record event, schedule, button, or
 subflow call:
 
+{/* os:check */}
 ```typescript
 import type { Flow } from '@objectstack/spec/automation';
 
@@ -63,6 +64,7 @@ registration/runtime.
 Use `StateMachineSchema` when the core requirement is "this object can only move
 through these states by these events."
 
+{/* os:check */}
 ```typescript
 import type { StateMachineConfig } from '@objectstack/spec/automation';
 
diff --git a/content/docs/concepts/architecture.mdx b/content/docs/concepts/architecture.mdx
index 581fc19d4f..9d765b0e3b 100644
--- a/content/docs/concepts/architecture.mdx
+++ b/content/docs/concepts/architecture.mdx
@@ -88,6 +88,7 @@ description — data (objects), automation (flows), access (permissions), and in
 
 ### Example: Defining a Customer Object
 
+{/* os:check */}
 ```typescript
 // src/objects/customer.object.ts
 import { ObjectSchema, Field } from '@objectstack/spec/data';
@@ -148,6 +149,7 @@ That's the job of the other layers.
 
 ### Example: Permission Rules
 
+{/* os:check */}
 ```typescript
 // src/permissions/sales_rep.permission.ts
 import { definePermissionSet } from '@objectstack/spec';
@@ -175,6 +177,7 @@ export const SalesRepPermission = definePermissionSet({
 
 ### Example: Workflow Automation
 
+{/* os:check */}
 ```typescript
 // src/flows/high_value_customer.flow.ts
 import { defineFlow } from '@objectstack/spec';
@@ -221,6 +224,7 @@ Kernel **orchestrates** these rules at runtime, independent of the data structur
 
 ### Example: List View
 
+{/* os:check */}
 ```typescript
 // src/views/customer.view.ts
 import { defineView } from '@objectstack/spec';
@@ -245,6 +249,7 @@ export const CustomerView = defineView({
 
 ### Example: Form View
 
+{/* os:check */}
 ```typescript
 // src/views/customer.view.ts
 import { defineView } from '@objectstack/spec';
@@ -300,6 +305,7 @@ User clicks "Save"
 
 ### Step 2: UI Layer Sends Request
 
+{/* os:check */}
 ```typescript
 // ObjectUI dispatches an action to Kernel
 const request = {
@@ -375,6 +381,7 @@ for (const workflow of workflows) {
 
 ### Step 7: ObjectUI Updates Display
 
+{/* os:check */}
 ```typescript
 // Kernel returns success response
 // UI optimistically updates the screen
@@ -388,6 +395,7 @@ Here's how all three protocols collaborate for a **Kanban Board** feature:
 
 ### 1. ObjectQL: Define the Data
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -426,6 +434,7 @@ export const Opportunity = ObjectSchema.create({
 
 ### 2. Kernel: Define Business Rules
 
+{/* os:check */}
 ```typescript
 import { defineFlow } from '@objectstack/spec';
 
@@ -450,6 +459,7 @@ export const OpportunityWonFlow = defineFlow({
 
 ### 3. ObjectUI: Define the Kanban View
 
+{/* os:check */}
 ```typescript
 import { defineView } from '@objectstack/spec';
 
diff --git a/content/docs/concepts/index.mdx b/content/docs/concepts/index.mdx
index 770a241834..d72da067d2 100644
--- a/content/docs/concepts/index.mdx
+++ b/content/docs/concepts/index.mdx
@@ -41,6 +41,7 @@ ObjectStack centralizes the "Intent" into a **single Protocol Definition**:
 
 <Tabs items={['Array Format', 'Map Format']}>
 <Tab value="Array Format">
+{/* os:check */}
 ```typescript
 // ONE definition — everything else derives from it
 import { defineStack } from '@objectstack/spec';
@@ -57,6 +58,7 @@ export default defineStack({
 ```
 </Tab>
 <Tab value="Map Format">
+{/* os:check */}
 ```typescript
 // Map keys become the `name` field automatically
 import { defineStack } from '@objectstack/spec';
diff --git a/content/docs/concepts/metadata-driven.mdx b/content/docs/concepts/metadata-driven.mdx
index ebd121bd1b..e28c6d9b54 100644
--- a/content/docs/concepts/metadata-driven.mdx
+++ b/content/docs/concepts/metadata-driven.mdx
@@ -72,6 +72,7 @@ ObjectStack centralizes the "Intent" into a **single TypeScript-authored, Zod-va
 
 ### Example: The ObjectStack Way
 
+{/* os:check */}
 ```typescript
 // ONE definition (in objectstack.config.ts)
 import { ObjectSchema, Field } from '@objectstack/spec/data';
@@ -112,6 +113,7 @@ In metadata-driven development, we embrace three core truths:
 
 The UI doesn't "build" a form; it **projects** the Object schema into visual components.
 
+{/* os:check */}
 ```typescript
 // Conceptual: the schema IS the form. The runtime renders a view
 // definition (a FormView metadata object) — there is no FormView
@@ -234,6 +236,7 @@ data, API, UI, and permissions in a single change — it can answer *"what break
 if I change this?"* instead of grepping and hoping. That turns AI from an
 autocomplete tool into a real co-maintainer.
 
+{/* os:check */}
 ```typescript
 // All you need:
 import { ObjectSchema, Field } from '@objectstack/spec/data';
@@ -332,6 +335,7 @@ When defining objects and metadata in ObjectStack, follow these strict rules and
 ### 1. Always Use `ObjectSchema.create()` with `Field.*` Helpers
 
 **✅ Correct:**
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -476,6 +480,7 @@ export const Account = ObjectSchema.create({
 
 ### Quick Reference
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
diff --git a/content/docs/data-modeling/analytics.mdx b/content/docs/data-modeling/analytics.mdx
index 9659eed895..8763923731 100644
--- a/content/docs/data-modeling/analytics.mdx
+++ b/content/docs/data-modeling/analytics.mdx
@@ -34,6 +34,7 @@ the object graph, and every surface references the same definition.
 
 ## Authoring a dataset
 
+{/* os:check */}
 ```ts
 // src/datasets/sales.dataset.ts
 import { defineDataset } from '@objectstack/spec/ui';
@@ -110,6 +111,7 @@ A `metric` (KPI) widget omits `dimensions` and shows the single measure value.
 
 ## Binding a report
 
+{/* os:check */}
 ```ts
 export const SalesByStageReport = {
   name: 'sales_by_stage',
diff --git a/content/docs/data-modeling/external-datasources.mdx b/content/docs/data-modeling/external-datasources.mdx
index d1de069528..bfe819fd43 100644
--- a/content/docs/data-modeling/external-datasources.mdx
+++ b/content/docs/data-modeling/external-datasources.mdx
@@ -26,6 +26,7 @@ the plain multi-datasource routing of **managed** databases ObjectStack owns, se
 Use `defineDatasource` with `schemaMode: 'external'`. The `external` block carries
 the federation policy (write gate, boot validation, credentials).
 
+{/* os:check */}
 ```typescript
 import { defineDatasource } from '@objectstack/spec/data';
 
diff --git a/content/docs/data-modeling/fields.mdx b/content/docs/data-modeling/fields.mdx
index 5616f66052..9b34255ef6 100644
--- a/content/docs/data-modeling/fields.mdx
+++ b/content/docs/data-modeling/fields.mdx
@@ -11,6 +11,7 @@ A **Field** defines an individual property within an Object. ObjectStack provide
 
 Fields are defined inside an Object's `fields` map using `Field.*` factory methods:
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
diff --git a/content/docs/data-modeling/formulas.mdx b/content/docs/data-modeling/formulas.mdx
index 104bfdb3b2..35c936a2df 100644
--- a/content/docs/data-modeling/formulas.mdx
+++ b/content/docs/data-modeling/formulas.mdx
@@ -34,6 +34,7 @@ plus the ObjectStack standard library.
 
 Every expression in metadata is persisted as the same envelope:
 
+{/* os:check */}
 ```ts
 type Expression = {
   dialect: 'cel' | 'cron' | 'template';
@@ -85,6 +86,7 @@ At **input** time you may write a bare string for shorthand — the spec
 transforms it into the right envelope based on the field type. The compiled
 artifact always contains the full envelope (and, after M9.2, the AST).
 
+{/* os:check */}
 ```ts
 import { F, P, cel, cron, tmpl } from '@objectstack/spec';
 import { ObjectSchema, Field } from '@objectstack/spec/data';
diff --git a/content/docs/data-modeling/index.mdx b/content/docs/data-modeling/index.mdx
index 90f1cff123..685705b262 100644
--- a/content/docs/data-modeling/index.mdx
+++ b/content/docs/data-modeling/index.mdx
@@ -9,6 +9,7 @@ Every ObjectStack application starts here: you declare **objects** (business ent
 
 A real object definition looks like this (from the CRM example app):
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
diff --git a/content/docs/data-modeling/indexing.mdx b/content/docs/data-modeling/indexing.mdx
index 7a0e3adf6f..e66b9a67c7 100644
--- a/content/docs/data-modeling/indexing.mdx
+++ b/content/docs/data-modeling/indexing.mdx
@@ -7,6 +7,7 @@ description: Optimize query performance with single-field, unique, compound, and
 
 Optimize query performance with indexes:
 
+{/* os:check */}
 ```typescript
 indexes: [
   // Single field index
diff --git a/content/docs/data-modeling/objects.mdx b/content/docs/data-modeling/objects.mdx
index a9f967645c..23a67954e0 100644
--- a/content/docs/data-modeling/objects.mdx
+++ b/content/docs/data-modeling/objects.mdx
@@ -9,6 +9,7 @@ An **Object** is the foundational metadata type in ObjectStack. It defines a bus
 
 ## Basic Structure
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -192,6 +193,7 @@ entirely.
 
 Optimize query performance:
 
+{/* os:check */}
 ```typescript
 indexes: [
   { fields: ['name'], type: 'btree', unique: false },
@@ -281,6 +283,7 @@ listing the verb in `apiMethods`.
 
 ## Complete Example
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
diff --git a/content/docs/data-modeling/queries.mdx b/content/docs/data-modeling/queries.mdx
index 25d1eee9e2..69d71c59fa 100644
--- a/content/docs/data-modeling/queries.mdx
+++ b/content/docs/data-modeling/queries.mdx
@@ -16,6 +16,7 @@ Quick reference for building queries with the ObjectStack QuerySchema.
 
 ## Basic Query Structure
 
+{/* os:check */}
 ```typescript
 const query = {
   object: 'task',
@@ -76,6 +77,7 @@ const query = {
 
 ### `$and` — All conditions must match
 
+{/* os:check */}
 ```typescript
 {
   where: {
@@ -89,6 +91,7 @@ const query = {
 
 ### `$or` — Any condition can match
 
+{/* os:check */}
 ```typescript
 {
   where: {
@@ -102,6 +105,7 @@ const query = {
 
 ### `$not` — Negate a condition
 
+{/* os:check */}
 ```typescript
 {
   where: {
@@ -112,6 +116,7 @@ const query = {
 
 ### Nested Logic
 
+{/* os:check */}
 ```typescript
 {
   where: {
@@ -134,6 +139,7 @@ const query = {
 
 Sort results with `orderBy` (array of sort nodes):
 
+{/* os:check */}
 ```typescript
 {
   orderBy: [
@@ -181,6 +187,7 @@ position from the previous page. There is no `keyset`/`after` query property.
 
 ### Select Specific Fields
 
+{/* os:check */}
 ```typescript
 {
   fields: ['id', 'title', 'status', 'created_at']
@@ -189,6 +196,7 @@ position from the previous page. There is no `keyset`/`after` query property.
 
 ### Nested / Related Fields
 
+{/* os:check */}
 ```typescript
 {
   fields: [
diff --git a/content/docs/data-modeling/schema-design.mdx b/content/docs/data-modeling/schema-design.mdx
index fe6ba9e3ad..c58c713fdf 100644
--- a/content/docs/data-modeling/schema-design.mdx
+++ b/content/docs/data-modeling/schema-design.mdx
@@ -181,6 +181,7 @@ editors. The group protocol is intentionally minimal (MVP):
 - Fields whose `group` is unset (or references an undeclared key) render
   in a default bucket after the declared groups.
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema } from '@objectstack/spec/data';
 
diff --git a/content/docs/data-modeling/validation.mdx b/content/docs/data-modeling/validation.mdx
index 0ba0d6cd9e..27ada7d15d 100644
--- a/content/docs/data-modeling/validation.mdx
+++ b/content/docs/data-modeling/validation.mdx
@@ -20,6 +20,7 @@ Three patterns that look like validation rules are deliberately **not** rule typ
 
 Validations are defined on an Object's `validations` array:
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -268,6 +269,7 @@ When multiple validations exist, `priority` controls execution order:
 
 ## Complete Example
 
+{/* os:check */}
 ```typescript
 validations: [
   // Formula validation
diff --git a/content/docs/deployment/tenancy-modes.mdx b/content/docs/deployment/tenancy-modes.mdx
index ace8da8aa9..1e5a197f51 100644
--- a/content/docs/deployment/tenancy-modes.mdx
+++ b/content/docs/deployment/tenancy-modes.mdx
@@ -33,6 +33,7 @@ framework detects that and turns tenant isolation on.
 Rather than re-deriving "what mode is this?" from the env flag, a service probe,
 or row counts, the platform exposes a single `tenancy` kernel service:
 
+{/* os:check */}
 ```ts
 interface TenancyService {
   mode: 'single' | 'multi';   // multi iff isolation is actually active
diff --git a/content/docs/deployment/validating-metadata.mdx b/content/docs/deployment/validating-metadata.mdx
index 187789bc89..6e2a5dc56a 100644
--- a/content/docs/deployment/validating-metadata.mdx
+++ b/content/docs/deployment/validating-metadata.mdx
@@ -171,6 +171,7 @@ entry renders; opening it fails permission-denied for everyone except a holder
 of the platform's built-in wildcard admin set. It works while you browse as an
 administrator and breaks for the users the app ships permission sets for.
 
+{/* os:check */}
 ```ts
 navigation: [{ id: 'nav_forecast', type: 'object', objectName: 'crm_forecast' }]
 // …and no permission set lists `crm_forecast` under `objects` → warning
diff --git a/content/docs/getting-started/build-with-claude-code.mdx b/content/docs/getting-started/build-with-claude-code.mdx
index 96b27abf7e..dff74f71c4 100644
--- a/content/docs/getting-started/build-with-claude-code.mdx
+++ b/content/docs/getting-started/build-with-claude-code.mdx
@@ -217,6 +217,7 @@ to the agent. ObjectStack turns those into loud, located build errors.
 Suppose the agent wrote the Resolve action's predicate as a **bare field
 reference** — `status` instead of `record.status`:
 
+{/* os:check */}
 ```typescript
 // ✗ Wrong — bare `status`. Type-checks (it's just a string), but at runtime
 //   it resolves to null, so the action is hidden on EVERY ticket.
diff --git a/content/docs/getting-started/common-patterns.mdx b/content/docs/getting-started/common-patterns.mdx
index e01da4d746..896185952b 100644
--- a/content/docs/getting-started/common-patterns.mdx
+++ b/content/docs/getting-started/common-patterns.mdx
@@ -28,6 +28,7 @@ Define a basic object with common fields for create, read, update, and delete op
 
 <Tabs items={['Array Format', 'Map Format']}>
 <Tab value="Array Format">
+{/* os:check */}
 ```typescript
 import { defineStack } from '@objectstack/spec';
 
@@ -57,6 +58,7 @@ export default defineStack({
 ```
 </Tab>
 <Tab value="Map Format">
+{/* os:check */}
 ```typescript
 import { defineStack } from '@objectstack/spec';
 
@@ -92,6 +94,7 @@ export default defineStack({
 
 Create a parent-child relationship between a master and its detail records. Note that `master_detail` defaults to `deleteBehavior: 'set_null'`; set `deleteBehavior: 'cascade'` explicitly if you want child records deleted with the parent.
 
+{/* os:check */}
 ```typescript
 {
   objects: [
@@ -150,6 +153,7 @@ Create a parent-child relationship between a master and its detail records. Note
 
 Create a list view with pre-configured filters and column display.
 
+{/* os:check */}
 ```typescript
 import { defineView } from '@objectstack/spec';
 
@@ -173,6 +177,7 @@ export const taskViews = defineView({
 
 Display records as a kanban board grouped by a status field.
 
+{/* os:check */}
 ```typescript
 import { defineView } from '@objectstack/spec';
 
@@ -195,6 +200,7 @@ export const taskBoard = defineView({
 
 Define an application with a structured navigation menu.
 
+{/* os:check */}
 ```typescript
 import { defineApp } from '@objectstack/spec';
 
@@ -247,6 +253,7 @@ or update in one flow**, use `record-after-write` (the create-OR-update union)
 instead of duplicating the definition — see
 [Flows › Create-or-update flow](/docs/automation/flows#create-or-update-flow-record-after-write).
 
+{/* os:check */}
 ```typescript
 import { defineFlow } from '@objectstack/spec';
 
@@ -373,6 +380,7 @@ Define a multi-step approval flow for records.
 
 Configure an AI agent with specific tools and instructions.
 
+{/* os:check */}
 ```typescript
 import { defineAgent } from '@objectstack/spec';
 
@@ -417,6 +425,7 @@ Implement pagination for large datasets using offset-based or cursor-based pagin
 
 ### Offset-Based (Simple)
 
+{/* os:check */}
 ```typescript
 // Page 1
 const page1 = {
@@ -464,6 +473,7 @@ const nextPage = {
 
 Restrict field visibility and editability based on user profiles.
 
+{/* os:check */}
 ```typescript
 {
   objects: [{
@@ -486,6 +496,7 @@ Restrict field visibility and editability based on user profiles.
 
 Who can actually read or edit a field is governed by permission sets — grant per-object CRUD, then narrow individual fields:
 
+{/* os:check */}
 ```typescript
 import { definePermissionSet } from '@objectstack/spec';
 
@@ -510,6 +521,7 @@ Combine these patterns into a complete `defineStack()` configuration:
 
 <Tabs items={['Array Format', 'Map Format']}>
 <Tab value="Array Format">
+{/* os:check */}
 ```typescript
 import { defineStack } from '@objectstack/spec';
 
@@ -538,6 +550,7 @@ export default defineStack({
 ```
 </Tab>
 <Tab value="Map Format">
+{/* os:check */}
 ```typescript
 import { defineStack } from '@objectstack/spec';
 
diff --git a/content/docs/getting-started/examples.mdx b/content/docs/getting-started/examples.mdx
index 9f9a9d345e..326d03d041 100644
--- a/content/docs/getting-started/examples.mdx
+++ b/content/docs/getting-started/examples.mdx
@@ -121,6 +121,7 @@ pnpm dev:todo
 
 **1. Define an object** — `src/objects/task.object.ts`:
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
diff --git a/content/docs/getting-started/quick-reference.mdx b/content/docs/getting-started/quick-reference.mdx
index 2b6da1c9ea..ec957745f4 100644
--- a/content/docs/getting-started/quick-reference.mdx
+++ b/content/docs/getting-started/quick-reference.mdx
@@ -266,6 +266,7 @@ Testing and quality assurance.
 
 ### Common Imports
 
+{/* os:check */}
 ```typescript
 // Data protocols
 import { FieldSchema, ObjectSchema, QuerySchema } from '@objectstack/spec/data';
diff --git a/content/docs/kernel/contracts/auth-service.mdx b/content/docs/kernel/contracts/auth-service.mdx
index a95e9fb0ba..26d8963c94 100644
--- a/content/docs/kernel/contracts/auth-service.mdx
+++ b/content/docs/kernel/contracts/auth-service.mdx
@@ -74,6 +74,7 @@ await authService.logout?.(session.id);
 
 The `AuthUser` object represents an authenticated user throughout the system.
 
+{/* os:check */}
 ```typescript
 export interface AuthUser {
   /** User identifier */
@@ -116,6 +117,7 @@ if (user) {
 
 ## AuthSession Interface
 
+{/* os:check */}
 ```typescript
 export interface AuthSession {
   /** Session identifier */
diff --git a/content/docs/kernel/contracts/cache-service.mdx b/content/docs/kernel/contracts/cache-service.mdx
index d7d97eef9c..9ae03f3964 100644
--- a/content/docs/kernel/contracts/cache-service.mdx
+++ b/content/docs/kernel/contracts/cache-service.mdx
@@ -32,6 +32,7 @@ export interface ICacheService {
 
 `CacheStats` is returned by `stats()` for monitoring:
 
+{/* os:check */}
 ```typescript
 export interface CacheStats {
   hits: number;          // Total number of cache hits
diff --git a/content/docs/kernel/contracts/data-engine.mdx b/content/docs/kernel/contracts/data-engine.mdx
index b234dd31c8..7b44a3dca9 100644
--- a/content/docs/kernel/contracts/data-engine.mdx
+++ b/content/docs/kernel/contracts/data-engine.mdx
@@ -237,6 +237,7 @@ the listener exists so callers that report per-field success (e.g. the flow
 engine's `update_record` step) can surface a warning instead of a silent
 success.
 
+{/* os:check */}
 ```typescript
 interface WriteObservabilityOptions {
   onFieldsDropped?: (event: DroppedFieldsEvent) => void;
diff --git a/content/docs/kernel/contracts/storage-service.mdx b/content/docs/kernel/contracts/storage-service.mdx
index e7e0a4cc65..4c16edf9a0 100644
--- a/content/docs/kernel/contracts/storage-service.mdx
+++ b/content/docs/kernel/contracts/storage-service.mdx
@@ -146,6 +146,7 @@ console.log(info.metadata);     // { objectType: 'task', ... }
 
 Configuration options for upload behavior.
 
+{/* os:check */}
 ```typescript
 export interface StorageUploadOptions {
   /** MIME content type */
@@ -226,6 +227,7 @@ const upload = await storageService.getPresignedUpload?.(
 
 ## Descriptor Types
 
+{/* os:check */}
 ```typescript
 export interface PresignedUploadDescriptor {
   uploadUrl: string;
@@ -273,6 +275,7 @@ const key = await storageService.completeChunkedUpload?.(uploadId, [
 
 The return type for file metadata (`getInfo`, `list`).
 
+{/* os:check */}
 ```typescript
 export interface StorageFileInfo {
   key: string;
diff --git a/content/docs/kernel/runtime-services/examples.mdx b/content/docs/kernel/runtime-services/examples.mdx
index f12151a4a7..bd4728a20d 100644
--- a/content/docs/kernel/runtime-services/examples.mdx
+++ b/content/docs/kernel/runtime-services/examples.mdx
@@ -7,6 +7,7 @@ description: Practical examples for flow nodes, hooks, and plugin event subscrip
 
 ## 1) Flow custom node: read related records
 
+{/* os:check */}
 ```ts
 export async function run(ctx: any) {
   const { record: order } = await ctx.services.data.get('sales_order', ctx.input.orderId);
@@ -25,6 +26,7 @@ export async function run(ctx: any) {
 
 ## 2) Hook: check sharing permission before mutation
 
+{/* os:check */}
 ```ts
 export async function beforeUpdate(ctx: any) {
   const ok = await ctx.services?.sharing?.canEdit('contract', ctx.input.id, {
diff --git a/content/docs/permissions/authentication.mdx b/content/docs/permissions/authentication.mdx
index dbf339fdfa..2093f35325 100644
--- a/content/docs/permissions/authentication.mdx
+++ b/content/docs/permissions/authentication.mdx
@@ -227,6 +227,7 @@ console.log('Current user:', session.data.user);
 
 #### Request Password Reset
 
+{/* os:check */}
 ```typescript
 // Direct API call
 const response = await fetch('http://localhost:3000/api/v1/auth/request-password-reset', {
@@ -240,6 +241,7 @@ const response = await fetch('http://localhost:3000/api/v1/auth/request-password
 
 #### Reset Password with Token
 
+{/* os:check */}
 ```typescript
 const response = await fetch('http://localhost:3000/api/v1/auth/reset-password', {
   method: 'POST',
@@ -290,6 +292,7 @@ by OTP self-signup.
 
 Always available once the plugin is on:
 
+{/* os:check */}
 ```typescript
 const response = await fetch('http://localhost:3000/api/v1/auth/sign-in/phone-number', {
   method: 'POST',
@@ -306,6 +309,7 @@ fail loudly with `NOT_SUPPORTED`. The public config advertises real
 availability as `features.phoneNumberOtp`, which is what the Console login UI
 gates its "Sign in with verification code" mode and the SMS reset branch on.
 
+{/* os:check */}
 ```typescript
 // Sign-in / verification: request a code, then verify (creates a session)
 await fetch('/api/v1/auth/phone-number/send-otp', {
@@ -551,6 +555,7 @@ const { totpURI, backupCodes } = await response.json();
 
 #### Verify 2FA Code
 
+{/* os:check */}
 ```typescript
 const response = await fetch('http://localhost:3000/api/v1/auth/two-factor/verify-totp', {
   method: 'POST',
@@ -584,6 +589,7 @@ new AuthPlugin({
 
 #### Send Magic Link
 
+{/* os:check */}
 ```typescript
 const response = await fetch('http://localhost:3000/api/v1/auth/sign-in/magic-link', {
   method: 'POST',
@@ -623,6 +629,7 @@ same flag. The plugin adds `sys_user.phone_number` (unique) and
 
 #### Sign In with Phone + Password
 
+{/* os:check */}
 ```typescript
 const response = await fetch('http://localhost:3000/api/v1/auth/sign-in/phone-number', {
   method: 'POST',
@@ -727,6 +734,7 @@ scrypt-hashed credential and can sign in immediately.
 
 #### Create a User Directly
 
+{/* os:check */}
 ```typescript
 const response = await fetch('http://localhost:3000/api/v1/auth/admin/create-user', {
   method: 'POST',
@@ -842,6 +850,7 @@ await client.auth.refreshToken('refresh-token-value');
 
 All endpoints are available at `/api/v1/auth/*`:
 
+{/* os:check */}
 ```typescript
 // Example: Login
 const response = await fetch('http://localhost:3000/api/v1/auth/sign-in/email', {
diff --git a/content/docs/permissions/permission-metadata.mdx b/content/docs/permissions/permission-metadata.mdx
index 75bdbedfc2..de1232a132 100644
--- a/content/docs/permissions/permission-metadata.mdx
+++ b/content/docs/permissions/permission-metadata.mdx
@@ -9,6 +9,7 @@ A **Permission Set** defines what a user can do within the application. It contr
 
 ## Basic Structure
 
+{/* os:check */}
 ```typescript
 const salesUserPermission = {
   name: 'sales_user',
@@ -148,6 +149,7 @@ tabPermissions: {
 
 Grant system-level capabilities:
 
+{/* os:check */}
 ```typescript
 systemPermissions: [
   'manage_users',
@@ -165,6 +167,7 @@ systemPermissions: [
 
 Define policies that restrict which records a user can access:
 
+{/* os:check */}
 ```typescript
 rowLevelSecurity: [
   {
@@ -215,6 +218,7 @@ sets bound to [positions](/docs/permissions/positions).
 
 ## Complete Example
 
+{/* os:check */}
 ```typescript
 const salesManagerPermission = {
   name: 'sales_manager',
diff --git a/content/docs/permissions/permission-sets.mdx b/content/docs/permissions/permission-sets.mdx
index 47a5cadb3f..37a8187156 100644
--- a/content/docs/permissions/permission-sets.mdx
+++ b/content/docs/permissions/permission-sets.mdx
@@ -13,6 +13,7 @@ via their [positions](/docs/permissions/positions), via direct grants, via
 the `everyone` anchor, and via the additive baseline. Any set that allows,
 wins; restriction is done by *not granting*.
 
+{/* os:check */}
 ```typescript
 import { definePermissionSet } from '@objectstack/spec/security';
 
diff --git a/content/docs/permissions/permissions-matrix.mdx b/content/docs/permissions/permissions-matrix.mdx
index c541035350..e960dd6b16 100644
--- a/content/docs/permissions/permissions-matrix.mdx
+++ b/content/docs/permissions/permissions-matrix.mdx
@@ -77,6 +77,7 @@ Permission sets are the only capability container (there is no Profile concept 
 
 ### Configuration Example
 
+{/* os:check */}
 ```typescript
 import { defineStack } from '@objectstack/spec';
 
diff --git a/content/docs/permissions/rls.mdx b/content/docs/permissions/rls.mdx
index 762daa292c..1659ef4c6b 100644
--- a/content/docs/permissions/rls.mdx
+++ b/content/docs/permissions/rls.mdx
@@ -29,6 +29,7 @@ RLS is the expert escape hatch. Reach for it when
 
 Policies live on a permission set under `rowLevelSecurity`:
 
+{/* os:check */}
 ```typescript
 import { definePermissionSet } from '@objectstack/spec';
 
diff --git a/content/docs/permissions/sso.mdx b/content/docs/permissions/sso.mdx
index 96fad62f07..f50c0b088e 100644
--- a/content/docs/permissions/sso.mdx
+++ b/content/docs/permissions/sso.mdx
@@ -127,6 +127,7 @@ packages that prefer wiring providers in code, or contributing them through
 
 ### Quick start — Okta
 
+{/* os:check */}
 ```ts
 const oidcProviders = [
   {
@@ -142,6 +143,7 @@ const oidcProviders = [
 
 ### Quick start — Azure AD (OIDC)
 
+{/* os:check */}
 ```ts
 const oidcProviders = [
   {
@@ -156,6 +158,7 @@ const oidcProviders = [
 
 ### Quick start — Keycloak
 
+{/* os:check */}
 ```ts
 const oidcProviders = [
   {
@@ -171,6 +174,7 @@ const oidcProviders = [
 
 ### Multiple enterprise providers
 
+{/* os:check */}
 ```ts
 const oidcProviders = [
   {
diff --git a/content/docs/plugins/adding-a-metadata-type.mdx b/content/docs/plugins/adding-a-metadata-type.mdx
index a1dcf3037a..7d895b5bc2 100644
--- a/content/docs/plugins/adding-a-metadata-type.mdx
+++ b/content/docs/plugins/adding-a-metadata-type.mdx
@@ -78,6 +78,7 @@ Schema. The registry entry shape is the same in both cases.
 Place the schema under the matching domain folder
 (e.g. `packages/spec/src/ui/my-widget.zod.ts`):
 
+{/* os:check */}
 ```ts
 import { z } from 'zod';
 
@@ -176,6 +177,7 @@ Common designer prop shapes already supported:
 No routing changes are required. The Studio app already includes the
 directory entry in its navigation:
 
+{/* os:check */}
 ```ts
 // studio.app.ts
 navigation: [
diff --git a/content/docs/plugins/development.mdx b/content/docs/plugins/development.mdx
index 340f141255..9adac9937d 100644
--- a/content/docs/plugins/development.mdx
+++ b/content/docs/plugins/development.mdx
@@ -58,6 +58,7 @@ Create `tsconfig.json`:
 
 A plugin package describes itself with a manifest validated by `ManifestSchema`. Create `src/manifest.ts`:
 
+{/* os:check */}
 ```typescript
 import { ManifestSchema } from '@objectstack/spec/kernel';
 
@@ -127,6 +128,7 @@ export function createHelloPlugin(): Plugin {
 
 Plugins can register new objects:
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema } from '@objectstack/spec/data';
 
@@ -265,6 +267,7 @@ Declare the capabilities your plugin needs in its manifest's `permissions` block
 
 Always use structured errors:
 
+{/* os:check */}
 ```typescript
 import type { EnhancedApiError } from '@objectstack/spec/api';
 
@@ -318,6 +321,7 @@ For plugins that extend the **ObjectStack Studio IDE**, use `defineStudioPlugin`
 
 ### Basic Studio Plugin
 
+{/* os:check */}
 ```typescript
 import { defineStudioPlugin } from '@objectstack/spec/studio';
 
@@ -343,6 +347,7 @@ export const manifest = defineStudioPlugin({
 
 Plugin IDs use reverse-domain notation and must match the pattern `^[a-z][a-z0-9-]*(\.[a-z][a-z0-9-]*)*$`:
 
+{/* os:check */}
 ```typescript
 // ✅ Valid IDs
 'objectstack.flow-designer'
@@ -370,6 +375,7 @@ Studio plugins can declare six types of contributions:
 
 ### Full Example with All Contributions
 
+{/* os:check */}
 ```typescript
 import { defineStudioPlugin } from '@objectstack/spec/studio';
 
diff --git a/content/docs/plugins/packages.mdx b/content/docs/plugins/packages.mdx
index 94a676beac..392bc78e4d 100644
--- a/content/docs/plugins/packages.mdx
+++ b/content/docs/plugins/packages.mdx
@@ -30,6 +30,7 @@ ObjectStack is organized into **71 package manifests** across multiple categorie
 - **When to use**: Import types, schemas, and builder functions when authoring metadata.
 - **Documentation**: [Protocol Reference](/docs/references)
 
+{/* os:check */}
 ```typescript
 import { defineStack, defineView } from '@objectstack/spec';
 import * as Data from '@objectstack/spec/data';
diff --git a/content/docs/protocol/backward-compatibility.mdx b/content/docs/protocol/backward-compatibility.mdx
index a7f0df6713..0452067156 100644
--- a/content/docs/protocol/backward-compatibility.mdx
+++ b/content/docs/protocol/backward-compatibility.mdx
@@ -32,6 +32,7 @@ ObjectStack follows [Semantic Versioning 2.0.0](https://semver.org/) (`MAJOR.MIN
 - **Enum values** are append-only within a MAJOR version. Existing values are never removed or renamed in MINOR/PATCH releases.
 - **Default values** in schemas are not changed in MINOR/PATCH releases unless fixing a documented bug.
 
+{/* os:check */}
 ```typescript
 // These imports are guaranteed stable within a MAJOR version
 import { FieldSchema, ObjectSchema } from '@objectstack/spec/data';
diff --git a/content/docs/protocol/kernel/config-resolution.mdx b/content/docs/protocol/kernel/config-resolution.mdx
index f3de61b9ca..4394b4895f 100644
--- a/content/docs/protocol/kernel/config-resolution.mdx
+++ b/content/docs/protocol/kernel/config-resolution.mdx
@@ -861,6 +861,7 @@ export async function someHandler({ context }) {
 ```
 
 ### 4. Provide Sensible Defaults
+{/* os:check */}
 ```typescript
 // ✓ GOOD: Plugin works out-of-box with defaults.
 // (Defaults ship as `default` on the plugin's settings-manifest
diff --git a/content/docs/protocol/kernel/i18n-standard.mdx b/content/docs/protocol/kernel/i18n-standard.mdx
index 5d92ca9c00..e807063d0a 100644
--- a/content/docs/protocol/kernel/i18n-standard.mdx
+++ b/content/docs/protocol/kernel/i18n-standard.mdx
@@ -218,6 +218,7 @@ const zh: TranslationData = {
 An admin (or an agent using the metadata API) authors one item per locale.
 The only difference from a file bundle is the top-level `locale`:
 
+{/* os:check */}
 ```typescript
 import { defineTranslation } from '@objectstack/spec/system';
 
@@ -590,6 +591,7 @@ context.i18n.formatNumber(smallNumber, {
 
 Plugins register translation bundles in their manifest:
 
+{/* os:check */}
 ```typescript
 // plugin.manifest.ts — a plugin manifest validated by `ManifestSchema`
 // from `@objectstack/spec/kernel` (there is no `definePlugin()` helper).
@@ -646,6 +648,7 @@ const welcome = i18n.t('crm.account.welcome', 'en');
 
 ObjectQL objects and fields can be **automatically translated**:
 
+{/* os:check */}
 ```typescript
 // Object definition
 import { ObjectSchema, Field } from '@objectstack/spec/data';
diff --git a/content/docs/protocol/kernel/lifecycle.mdx b/content/docs/protocol/kernel/lifecycle.mdx
index 46bda516dd..8e2951389e 100644
--- a/content/docs/protocol/kernel/lifecycle.mdx
+++ b/content/docs/protocol/kernel/lifecycle.mdx
@@ -439,6 +439,7 @@ non-trivial column renames).
 
 #### Declarative schema (the default)
 
+{/* os:check */}
 ```typescript
 // src/objects/salesforce_account.object.ts
 import { ObjectSchema, Field } from '@objectstack/spec/data';
@@ -473,6 +474,7 @@ os generate migration --dry-run     # Preview without writing
 The generated TypeScript file uses plain Knex-style `up(db)` / `down(db)`
 functions — no custom migration DSL:
 
+{/* os:check */}
 ```typescript
 // migrations/20260101000000_migration.ts — auto-generated
 export async function up(db: any): Promise<void> {
@@ -735,6 +737,7 @@ await step2(); // If this fails, step1 is not reverted!
 ### 2. Version Migrations, Don't Modify Them
 Once a migration file is applied in production, **never modify it**. Generate a new one instead.
 
+{/* os:check */}
 ```typescript
 // ✗ BAD: Modifying an existing migration file
 // migrations/20260101000000_migration.ts (ALREADY APPLIED)
diff --git a/content/docs/protocol/kernel/metadata-service.mdx b/content/docs/protocol/kernel/metadata-service.mdx
index f8cf93c5be..816340d38e 100644
--- a/content/docs/protocol/kernel/metadata-service.mdx
+++ b/content/docs/protocol/kernel/metadata-service.mdx
@@ -70,6 +70,7 @@ Loaders adapt different storage backends to a common interface.
 
 Each Loader declares its capabilities via a **Contract**:
 
+{/* os:check */}
 ```typescript
 export interface MetadataLoaderContract {
   name: string;
diff --git a/content/docs/protocol/kernel/plugin-spec.mdx b/content/docs/protocol/kernel/plugin-spec.mdx
index bed90f862c..c2f111a9b8 100644
--- a/content/docs/protocol/kernel/plugin-spec.mdx
+++ b/content/docs/protocol/kernel/plugin-spec.mdx
@@ -240,6 +240,7 @@ A well-organized plugin follows this **standard structure**:
 
 Define database objects using ObjectQL schema syntax:
 
+{/* os:check */}
 ```typescript
 // src/objects/account.object.ts
 import { ObjectSchema, Field } from '@objectstack/spec/data';
@@ -288,6 +289,7 @@ export const Account = ObjectSchema.create({
 
 Define user interfaces using ObjectUI layout DSL:
 
+{/* os:check */}
 ```typescript
 // src/views/account_list.view.ts
 import { defineView } from '@objectstack/spec';
@@ -357,6 +359,7 @@ export default defineTrigger({
 
 Define plugin configuration with Zod for validation:
 
+{/* os:check */}
 ```typescript
 // src/config.schema.ts
 import { z } from 'zod';
diff --git a/content/docs/protocol/kernel/runtime-capabilities.mdx b/content/docs/protocol/kernel/runtime-capabilities.mdx
index 317d05d625..5595888e90 100644
--- a/content/docs/protocol/kernel/runtime-capabilities.mdx
+++ b/content/docs/protocol/kernel/runtime-capabilities.mdx
@@ -513,6 +513,7 @@ const capabilities =
 
 Always document which capabilities your feature requires:
 
+{/* os:check */}
 ```typescript
 /**
  * Semantic Search Component
diff --git a/content/docs/protocol/objectql/query-syntax.mdx b/content/docs/protocol/objectql/query-syntax.mdx
index 3a6eac18c6..cca3c6a3d3 100644
--- a/content/docs/protocol/objectql/query-syntax.mdx
+++ b/content/docs/protocol/objectql/query-syntax.mdx
@@ -24,6 +24,7 @@ LIMIT 10;
 ```
 
 **ObjectQL (Canonical Spec Format):**
+{/* os:check */}
 ```typescript
 import type { QueryAST } from '@objectstack/spec/data';
 
@@ -292,6 +293,7 @@ const query: QueryAST = {
 
 ### Date Filters
 
+{/* os:check */}
 ```typescript
 // Specific date
 where: { created_at: '2024-01-15' }
@@ -306,6 +308,7 @@ where: { created_at: { $gte: '2024-01-01' } }
 
 ### Null Checks
 
+{/* os:check */}
 ```typescript
 // Field IS NULL
 where: { manager_id: { $null: true } }
@@ -796,6 +799,7 @@ The tuple/array format (e.g. `['status', '=', 'active']`) and the `filters` key
 
 Before entering the ObjectQL protocol or `IDataEngine`, tuple filters **must** be converted to the canonical `where` + `$op` object format using the `parseFilterAST()` utility from `@objectstack/spec/data`:
 
+{/* os:check */}
 ```typescript
 import { parseFilterAST } from '@objectstack/spec/data';
 
diff --git a/content/docs/protocol/objectql/schema.mdx b/content/docs/protocol/objectql/schema.mdx
index c5b506a71d..47b8a7dea6 100644
--- a/content/docs/protocol/objectql/schema.mdx
+++ b/content/docs/protocol/objectql/schema.mdx
@@ -46,6 +46,7 @@ label: Customer
 ```
 
 **TypeScript (Recommended for strict validation):**
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -128,6 +129,7 @@ validations:
 
 **TypeScript Complete Example:**
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -621,6 +623,7 @@ Record-triggered logic is **not** an object-schema field — `triggers` (and `ho
 `src/objects/<name>.hook.ts` module as a typed `Hook` and export it (or model the
 automation as a top-level `record_change` flow).
 
+{/* os:check */}
 ```typescript
 // src/objects/customer.hook.ts
 import { Hook, HookContext } from '@objectstack/spec/data';
diff --git a/content/docs/protocol/objectql/state-machine.mdx b/content/docs/protocol/objectql/state-machine.mdx
index 1784855b6d..9d96d87bec 100644
--- a/content/docs/protocol/objectql/state-machine.mdx
+++ b/content/docs/protocol/objectql/state-machine.mdx
@@ -24,6 +24,7 @@ In the era of **AI Agents**, field-level validation is not enough. Large Languag
 
 Add a `state_machine` rule to the object's `validations` array. The rule names the state `field` and declares a `transitions` map of `{ currentValue: [allowedNextValues] }`.
 
+{/* os:check */}
 ```typescript
 import { ObjectSchema, Field } from '@objectstack/spec/data';
 
@@ -123,6 +124,7 @@ Because the transition table is data, both UIs and Agents can ask "from this sta
 
 For complex business objects (like `Lead`, `Opportunity`, or `Order`), a transition table can grow large. To keep your object definition readable, extract the rule(s) into a plain TypeScript constant — there is no special `*.state.ts` format or `StateMachineConfig` type for object lifecycles; it is just an array of validation rules.
 
+{/* os:check */}
 ```typescript
 // src/objects/lead.validations.ts
 export const leadValidations = [
diff --git a/content/docs/protocol/objectui/index.mdx b/content/docs/protocol/objectui/index.mdx
index 57291f5641..c0e379c39c 100644
--- a/content/docs/protocol/objectui/index.mdx
+++ b/content/docs/protocol/objectui/index.mdx
@@ -224,6 +224,7 @@ actions:
 
 ### FormView: Record Editing
 
+{/* os:check */}
 ```typescript
 import { defineView } from '@objectstack/spec/ui';
 
@@ -248,6 +249,7 @@ defineView({
 
 ### ListView: Data Tables
 
+{/* os:check */}
 ```typescript
 import { defineView } from '@objectstack/spec/ui';
 
@@ -277,6 +279,7 @@ defineView({
 
 ### Dashboard: Analytics Composition
 
+{/* os:check */}
 ```typescript
 import { Dashboard } from '@objectstack/spec/ui';
 
diff --git a/content/docs/protocol/objectui/layout-dsl.mdx b/content/docs/protocol/objectui/layout-dsl.mdx
index b46d7f0b81..e8f5e89ffe 100644
--- a/content/docs/protocol/objectui/layout-dsl.mdx
+++ b/content/docs/protocol/objectui/layout-dsl.mdx
@@ -780,6 +780,7 @@ interface FormField {
 
 ### Responsive Columns
 
+{/* os:check */}
 ```typescript
 // Source: packages/spec/src/ui/responsive.zod.ts (BreakpointColumnMapSchema)
 // Grid columns (1-12) per named breakpoint. All entries optional.
@@ -801,6 +802,7 @@ layer — data fields, view form sections/fields, and page components — aligni
 the `readonlyWhen` / `requiredWhen` family. The element is shown only when the
 expression evaluates truthy.
 
+{/* os:check */}
 ```typescript
 // e.g. on a PageComponent:
 visibleWhen: "record.account_type == 'premium'"
diff --git a/content/docs/protocol/objectui/record-alert.mdx b/content/docs/protocol/objectui/record-alert.mdx
index 76c953bbcd..d1284153c6 100644
--- a/content/docs/protocol/objectui/record-alert.mdx
+++ b/content/docs/protocol/objectui/record-alert.mdx
@@ -40,6 +40,7 @@ Common use cases:
 
 `record:alert` is registered as a slot component in the slotted page schema. Add it to the `alerts` slot of your `*.page.ts`:
 
+{/* os:check */}
 ```ts
 import { definePage } from '@objectstack/spec/ui';
 
@@ -88,6 +89,7 @@ The `visible` predicate uses the same CEL pipeline every condition in the framew
 
 Examples:
 
+{/* os:check */}
 ```ts
 visible: 'record.id == os.user.id && record.email_verified == false'
 visible: 'record.status == "locked"'
diff --git a/content/docs/protocol/objectui/widget-contract.mdx b/content/docs/protocol/objectui/widget-contract.mdx
index 63a899a149..73d03c1076 100644
--- a/content/docs/protocol/objectui/widget-contract.mdx
+++ b/content/docs/protocol/objectui/widget-contract.mdx
@@ -204,6 +204,7 @@ implementation:
 
 Widget lifecycle hooks are defined on the manifest as **code-body strings** (not function references). They follow `WidgetLifecycleSchema`:
 
+{/* os:check */}
 ```typescript
 interface WidgetLifecycle {
   onMount?: string;     // Initialization when the widget mounts
@@ -229,6 +230,7 @@ lifecycle:
 
 A widget can declare custom events it emits via `WidgetEventSchema`:
 
+{/* os:check */}
 ```typescript
 interface WidgetEvent {
   name: string;                          // lowercase, dash-separated, e.g. 'value-change'
@@ -255,6 +257,7 @@ events:
 
 A widget exposes configuration knobs through `WidgetPropertySchema`. These describe the options a builder can set when placing the widget:
 
+{/* os:check */}
 ```typescript
 interface WidgetProperty {
   name: string;          // camelCase
@@ -284,6 +287,7 @@ properties:
 
 A widget manifest carries ARIA metadata through the shared `AriaProps` schema (`packages/spec/src/ui/i18n.zod.ts`). The supported attributes are intentionally minimal:
 
+{/* os:check */}
 ```typescript
 interface AriaProps {
   ariaLabel?: string;       // Accessible label for screen readers
diff --git a/content/docs/ui/apps.mdx b/content/docs/ui/apps.mdx
index 1f43edb79f..002a74d597 100644
--- a/content/docs/ui/apps.mdx
+++ b/content/docs/ui/apps.mdx
@@ -9,6 +9,7 @@ An **App** is a logical container that bundles objects, views, pages, and dashbo
 
 ## Basic Structure
 
+{/* os:check */}
 ```typescript
 const crmApp = {
   name: 'crm',
@@ -169,6 +170,7 @@ mobileNavigation: {
 
 ## Complete Example
 
+{/* os:check */}
 ```typescript
 const projectApp = {
   name: 'project_management',
diff --git a/content/docs/ui/create-vs-edit-form.mdx b/content/docs/ui/create-vs-edit-form.mdx
index 768b9c7d45..ad1f9af719 100644
--- a/content/docs/ui/create-vs-edit-form.mdx
+++ b/content/docs/ui/create-vs-edit-form.mdx
@@ -36,6 +36,7 @@ The full edit form materialises each `field.group` into a section. You can omit
 
 The escape hatch is a **named form view** bound to the create entry point. Author it as a **sparse override** — mostly a list of field names — not a from-scratch restatement:
 
+{/* os:check */}
 ```ts
 import { defineView } from '@objectstack/spec';
 
diff --git a/content/docs/ui/dashboards.mdx b/content/docs/ui/dashboards.mdx
index 929d8ff14a..b366399bee 100644
--- a/content/docs/ui/dashboards.mdx
+++ b/content/docs/ui/dashboards.mdx
@@ -14,6 +14,7 @@ the dataset's `dimensions` and `values` by name. The dataset owns the base
 object, joins, and measures, so the same numbers stay consistent
 across every dashboard and report.
 
+{/* os:check */}
 ```typescript
 const salesDashboard = {
   name: 'sales_overview',
@@ -165,6 +166,7 @@ stay consistent across surfaces.
 > `aggregate` directly on the widget) was removed in the ADR-0021 single-form
 > cutover. Define a dataset and bind widgets to it instead.
 
+{/* os:check */}
 ```typescript
 import { defineDataset } from '@objectstack/spec/ui';
 
@@ -346,6 +348,7 @@ dateRange: {
 
 Add interactive filter controls that apply to all widgets:
 
+{/* os:check */}
 ```typescript
 globalFilters: [
   { name: 'region', field: 'region', label: 'Region', type: 'select' },
@@ -365,6 +368,7 @@ range defaults to `dateRange.field ?? 'created_at'`). When a widget stores
 the concept under a different field — or should ignore a filter — declare
 `filterBindings` on the widget:
 
+{/* os:check */}
 ```typescript
 widgets: [
   // Default binding: dateRange → created_at, region → region.
@@ -388,6 +392,7 @@ filter's own `field`.
 
 First define the dataset the widgets bind to:
 
+{/* os:check */}
 ```typescript
 import { defineDataset } from '@objectstack/spec/ui';
 
@@ -410,6 +415,7 @@ export const projectTasksDataset = defineDataset({
 
 Then bind the dashboard widgets to it:
 
+{/* os:check */}
 ```typescript
 const projectDashboard = {
   name: 'project_overview',
diff --git a/content/docs/ui/forms.mdx b/content/docs/ui/forms.mdx
index cde840bd17..ce26f72ac4 100644
--- a/content/docs/ui/forms.mdx
+++ b/content/docs/ui/forms.mdx
@@ -51,6 +51,7 @@ Only the spec'd whitelist of form fields is accepted; everything else (status, o
 
 ## 1. Declare the form view
 
+{/* os:check */}
 ```ts
 // hotcrm/src/views/lead.view.ts  (https://github.com/objectstack-ai/hotcrm)
 import { defineView } from '@objectstack/spec';
@@ -105,6 +106,7 @@ an older runtime, or object hooks that branch on the `guest_portal` permission).
 When present it is still attached to the anonymous context, so keep it
 INSERT-only on the target object — the guest-safe shape (ADR-0090 D9).
 
+{/* os:check */}
 ```ts
 // hotcrm/src/security/guest-portal.permission.ts
 import { definePermissionSet } from '@objectstack/spec/security';
@@ -128,6 +130,7 @@ Anonymous submitters cannot be trusted to set `lead_source`, `status`, `owner`,
 - Apply safe defaults (`status='new'`, `lead_source='web'`, …)
 - Strip any internal fields that slipped past the whitelist
 
+{/* os:check */}
 ```ts
 // hotcrm/src/objects/lead.hook.ts
 import type { Hook, HookContext } from '@objectstack/spec/data';
@@ -344,6 +347,7 @@ formViews: {
 
 App actions can declare `type: 'form'` to open a FormView without resorting to free-form URLs. The `target` is the FormView name; the runtime navigates to `/console/forms/:name`.
 
+{/* os:check */}
 ```ts
 // hotcrm/src/actions/new-lead.action.ts
 import { Action } from '@objectstack/spec/ui';
diff --git a/content/docs/ui/index.mdx b/content/docs/ui/index.mdx
index b9fd415d47..6cc32d9717 100644
--- a/content/docs/ui/index.mdx
+++ b/content/docs/ui/index.mdx
@@ -9,6 +9,7 @@ The UI engine turns metadata into user interfaces: you declare **apps**, **views
 
 An app is a navigation shell over your objects (from the CRM example app):
 
+{/* os:check */}
 ```typescript
 import { App } from '@objectstack/spec/ui';
 
diff --git a/content/docs/ui/pages.mdx b/content/docs/ui/pages.mdx
index 1b9efdf520..7ac4790be5 100644
--- a/content/docs/ui/pages.mdx
+++ b/content/docs/ui/pages.mdx
@@ -9,6 +9,7 @@ A **Page** defines a custom UI layout using components, regions, and variables.
 
 ## Basic Structure
 
+{/* os:check */}
 ```typescript
 const homePage = {
   name: 'sales_home',
@@ -83,6 +84,7 @@ Earlier roadmap types (`dashboard`, `form`, `record_detail`, `record_review`, `o
 
 Regions define layout zones on the page. Each region contains components.
 
+{/* os:check */}
 ```typescript
 regions: [
   {
@@ -154,6 +156,7 @@ Components may also carry `dataSource` (per-element object binding for multi-obj
 
 Pages can define local variables for managing state across components.
 
+{/* os:check */}
 ```typescript
 variables: [
   {
@@ -173,6 +176,7 @@ Variable `type` accepts `'string'` (default), `'number'`, `'boolean'`, `'object'
 
 ## Complete Example
 
+{/* os:check */}
 ```typescript
 const accountRecordPage = {
   name: 'account_detail',
diff --git a/content/docs/ui/translations.mdx b/content/docs/ui/translations.mdx
index 5c40c51f4b..d2194a2869 100644
--- a/content/docs/ui/translations.mdx
+++ b/content/docs/ui/translations.mdx
@@ -143,6 +143,7 @@ Files are not the only door. A `translation` metadata item — created in the
 Studio, through the metadata API, or by an agent — carries one locale's worth
 of the **same** groups a file bundle uses, plus the `locale` it translates:
 
+{/* os:check */}
 ```ts
 import { defineTranslation } from '@objectstack/spec/system';
 
diff --git a/content/docs/ui/views.mdx b/content/docs/ui/views.mdx
index daad8f60f3..ee837f9647 100644
--- a/content/docs/ui/views.mdx
+++ b/content/docs/ui/views.mdx
@@ -11,6 +11,7 @@ A **View** defines how records of an Object are displayed to users. ObjectStack
 
 Views are authored **per object** inside a `defineView({ ... })` container — the default `list`, named `listViews`, and named `formViews` all live in one document. The loader expands the container into independently addressable `<object>.<key>` view items that power the view switcher.
 
+{/* os:check */}
 ```typescript
 // src/ui/views/task.view.ts
 import { defineView } from '@objectstack/spec';
@@ -118,6 +119,7 @@ List and form views share that one namespace — don't reuse a key.
 
 ### Column Configuration
 
+{/* os:check */}
 ```typescript
 columns: [
   {
@@ -287,6 +289,7 @@ formViews: {
 
 Each field in a form section can be customized:
 
+{/* os:check */}
 ```typescript
 fields: [
   {
@@ -320,6 +323,7 @@ fields: [
 
 One container covering a default grid, a kanban saved view, and a tabbed edit form — mirroring `examples/app-showcase/src/ui/views/task.view.ts`:
 
+{/* os:check */}
 ```typescript
 import { defineView } from '@objectstack/spec';
 
diff --git a/packages/spec/scripts/check-skill-examples.ts b/packages/spec/scripts/check-skill-examples.ts
index 9100c65d8e..bae62bcc3f 100644
--- a/packages/spec/scripts/check-skill-examples.ts
+++ b/packages/spec/scripts/check-skill-examples.ts
@@ -45,12 +45,50 @@ import path from 'path';
 
 const REPO_ROOT = path.resolve(__dirname, '../../..');
 const SPEC_DIR = path.resolve(__dirname, '..');
-const SKILLS_DIR = path.resolve(REPO_ROOT, 'skills');
 const BUILD_DIR = path.resolve(SPEC_DIR, '.examples-build');
 const SPEC_PKG_JSON = path.resolve(SPEC_DIR, 'package.json');
 
-/** Opt-in marker: the line directly above a fence opts that block into the gate. */
-const MARKER = '<!-- os:check -->';
+/**
+ * Prose trees whose code examples are copied verbatim by humans and AI, and so
+ * must compile against the real spec.
+ *
+ * `skills/` was the original scope (#3094); `content/docs/` was not covered, and
+ * the gap had exactly the shape this gate exists to close. When
+ * `tool.requiresConfirmation` was removed (#3715) this gate caught the now-broken
+ * `defineTool` example in `skills/objectstack-ai/SKILL.md` — the identical break
+ * in a docs page would have shipped, because nothing compiled those pages. A
+ * gate covering a fraction of the surface it appears to cover reads as coverage.
+ *
+ * `content/docs/references/` is excluded: `build-docs.ts` regenerates it from the
+ * schemas, so its snippets cannot drift independently of their source.
+ */
+const SOURCE_ROOTS: Array<{
+  dir: string;
+  ext: string;
+  label: string;
+  marker: string;
+  exclude?: string[];
+}> = [
+  { dir: path.resolve(REPO_ROOT, 'skills'), ext: '.md', label: 'skills', marker: '<!-- os:check -->' },
+  {
+    dir: path.resolve(REPO_ROOT, 'content/docs'),
+    ext: '.mdx',
+    label: 'docs',
+    // MDX has no HTML comments — fumadocs-mdx fails the build outright on
+    // `<!-- … -->` ("Unexpected character `!`… to create a comment in MDX, use
+    // `{/* text */}`"). The marker must follow each format's own comment syntax.
+    marker: '{/* os:check */}',
+    exclude: [path.resolve(REPO_ROOT, 'content/docs/references')],
+  },
+];
+
+/**
+ * Every marker spelling, in any root. A block tagged with the WRONG root's
+ * spelling would be silently unchecked (and, in `.mdx`, would also break the
+ * docs build), so both forms are recognised for orphan detection and only the
+ * root's own form actually opts a block in.
+ */
+const ALL_MARKERS = ['<!-- os:check -->', '{/* os:check */}'];
 
 const KEEP = process.argv.includes('--keep');
 
@@ -69,21 +107,32 @@ interface Example {
   fileName: string;
 }
 
-/** Every `*.md` under a skill folder — SKILL.md plus references/rules notes. */
-function skillMarkdownFiles(): string[] {
-  if (!fs.existsSync(SKILLS_DIR)) return [];
-  const out: string[] = [];
-  const walk = (dir: string) => {
-    for (const e of fs.readdirSync(dir, { withFileTypes: true })) {
-      const full = path.join(dir, e.name);
-      if (e.isDirectory()) walk(full);
-      else if (e.name.endsWith('.md')) out.push(full);
-    }
-  };
-  for (const e of fs.readdirSync(SKILLS_DIR, { withFileTypes: true })) {
-    if (e.isDirectory()) walk(path.join(SKILLS_DIR, e.name));
+/** Every candidate prose file across `SOURCE_ROOTS`, with the root that owns it. */
+function sourceFiles(): Array<{ file: string; root: (typeof SOURCE_ROOTS)[number] }> {
+  const out: Array<{ file: string; root: (typeof SOURCE_ROOTS)[number] }> = [];
+  for (const root of SOURCE_ROOTS) {
+    if (!fs.existsSync(root.dir)) continue;
+    const walk = (dir: string) => {
+      if (root.exclude?.some((x) => dir === x || dir.startsWith(x + path.sep))) return;
+      for (const e of fs.readdirSync(dir, { withFileTypes: true })) {
+        const full = path.join(dir, e.name);
+        if (e.isDirectory()) walk(full);
+        else if (e.name.endsWith(root.ext)) out.push({ file: full, root });
+      }
+    };
+    walk(root.dir);
   }
-  return out.sort();
+  return out.sort((a, b) => a.file.localeCompare(b.file));
+}
+
+/**
+ * Flat, collision-free build-dir name for a block: `<root>__<path>__<n>.ts`.
+ * Path separators become `_` so two pages of the same basename in different
+ * folders (`ui/actions.mdx`, `protocol/objectui/actions.mdx`) cannot collide.
+ */
+function buildFileName(source: string, root: (typeof SOURCE_ROOTS)[number], n: number): string {
+  const relPath = path.relative(root.dir, source).replace(new RegExp(`\\${root.ext}$`), '');
+  return `${root.label}__${relPath.split(path.sep).join('_')}__${n}.ts`;
 }
 
 /**
@@ -96,10 +145,11 @@ function skillMarkdownFiles(): string[] {
  * json block) silently checks nothing — exactly the failure mode this gate
  * exists to prevent — so the caller treats an orphan as an error, not a no-op.
  */
-function extractFromFile(source: string): { examples: Example[]; orphans: number[] } {
+function extractFromFile(
+  source: string,
+  root: (typeof SOURCE_ROOTS)[number],
+): { examples: Example[]; orphans: number[] } {
   const lines = fs.readFileSync(source, 'utf-8').split('\n');
-  const skillDir = path.relative(SKILLS_DIR, source).split(path.sep)[0];
-  const base = path.basename(source, '.md');
   const examples: Example[] = [];
   const claimed = new Set<number>(); // MARKER line indices that opened a real block
   let n = 0;
@@ -107,7 +157,7 @@ function extractFromFile(source: string): { examples: Example[]; orphans: number
   for (let i = 0; i < lines.length; i++) {
     const open = lines[i].match(/^```(ts|typescript)\s*$/);
     if (!open) continue;
-    const marked = i > 0 && lines[i - 1].trim() === MARKER;
+    const marked = i > 0 && lines[i - 1].trim() === root.marker;
     // Find the matching close fence regardless of marking, so `i` advances past
     // this block and we never treat its body as top-level markdown.
     let close = i + 1;
@@ -120,7 +170,7 @@ function extractFromFile(source: string): { examples: Example[]; orphans: number
         source,
         bodyStartLine: i + 2, // 1-based line of body[0]
         code: body.join('\n'),
-        fileName: `${skillDir}__${base}__${n}.ts`,
+        fileName: buildFileName(source, root, n),
       });
     }
     i = close; // skip to the close fence
@@ -128,7 +178,9 @@ function extractFromFile(source: string): { examples: Example[]; orphans: number
 
   const orphans: number[] = [];
   for (let i = 0; i < lines.length; i++) {
-    if (lines[i].trim() === MARKER && !claimed.has(i)) orphans.push(i + 1); // 1-based
+    // Any marker spelling counts as an orphan claim — a wrong-format marker
+    // checks nothing, which is precisely what this guard exists to catch.
+    if (ALL_MARKERS.includes(lines[i].trim()) && !claimed.has(i)) orphans.push(i + 1); // 1-based
   }
   return { examples, orphans };
 }
@@ -260,13 +312,13 @@ function fail(message: string): never {
 }
 
 function main() {
-  console.log('🧪 Type-checking skill TypeScript examples...\n');
+  console.log('🧪 Type-checking prose TypeScript examples (skills + docs)...\n');
 
-  const files = skillMarkdownFiles();
+  const files = sourceFiles();
   const examples: Example[] = [];
   const orphans: string[] = [];
-  for (const file of files) {
-    const { examples: found, orphans: bad } = extractFromFile(file);
+  for (const { file, root } of files) {
+    const { examples: found, orphans: bad } = extractFromFile(file, root);
     examples.push(...found);
     for (const line of bad) orphans.push(`${rel(file)}:${line}`);
   }
@@ -276,7 +328,8 @@ function main() {
   // no marker, because it looks intentional.
   if (orphans.length > 0) {
     fail(
-      `Found ${MARKER} not directly above a \`\`\`ts / \`\`\`typescript fence:\n\n` +
+      `Found an os:check marker not directly above a \`\`\`ts / \`\`\`typescript fence\n` +
+        `(or written in the wrong comment syntax for its file type):\n\n` +
         orphans.map((o) => `  - ${o}`).join('\n') +
         `\n\n  The marker must be the line IMMEDIATELY above the code fence (no blank\n` +
         `  line between). Move it, or remove it if the block should not be checked.`,
@@ -288,10 +341,10 @@ function main() {
   // A gate that checks nothing must not report success.
   if (examples.length === 0) {
     fail(
-      `No skill examples are marked for type-checking.\n\n` +
+      `No prose examples are marked for type-checking.\n\n` +
         `  Mark a self-contained, compilable block by putting\n\n` +
-        `    ${MARKER}\n\n` +
-        `  on the line directly above its \`\`\`ts fence in a skills/**/*.md file.\n` +
+        SOURCE_ROOTS.map((r) => `    ${r.marker}   (in ${rel(r.dir)}/**/*${r.ext})`).join('\n') + `\n\n` +
+        `  on the line directly above its \`\`\`ts fence in ${SOURCE_ROOTS.map((r) => `${rel(r.dir)}/**/*${r.ext}`).join(' or ')}.\n` +
         `  (If you just removed the last marker, that is almost certainly a mistake.)`,
     );
   }
@@ -319,14 +372,14 @@ function main() {
   const diags = parseDiagnostics(output);
 
   if (code === 0 && diags.length === 0) {
-    console.log(`✅ ${examples.length} skill examples type-check against @objectstack/spec`);
+    console.log(`✅ ${examples.length} prose examples type-check against @objectstack/spec`);
     if (!KEEP) fs.rmSync(BUILD_DIR, { recursive: true, force: true });
     return;
   }
 
-  // Remap every diagnostic back to skills/**/SKILL.md:<real line> so the author
+  // Remap every diagnostic back to the source page:<real line> so the author
   // reads the error against the file they actually edit, not the throwaway copy.
-  console.error(`\n✗ Skill TypeScript examples do not compile against @objectstack/spec:\n`);
+  console.error(`\n✗ Prose TypeScript examples do not compile against @objectstack/spec:\n`);
   const grouped = new Map<string, string[]>();
   for (const d of diags) {
     const ex = byFile.get(d.file);
@@ -348,7 +401,7 @@ function main() {
 
   console.error(
     `\n  These are examples an AI copies verbatim. Fix the example to match the\n` +
-      `  current spec, or drop its ${MARKER} marker if it is an intentional fragment.\n`,
+      `  current spec, or drop its os:check marker if it is an intentional fragment.\n`,
   );
   if (!KEEP) fs.rmSync(BUILD_DIR, { recursive: true, force: true });
   process.exit(1);