@@ -0,0 +1,14 @@
+---
+"@objectstack/lint": minor
+---
+
+The runtime publish gate now judges `datasource` writes: `lintLivenessProperties` declares the type in `runtimeTypes` and `TYPE_TO_STACK_KEY` maps it onto `datasources`, so a datasource minted through Studio, REST `/meta` or an MCP/AI author reaches an authoring rule for the first time.
+
+Clause-②: yes (widening) — one metadata type joins an existing rule's declared roster. No schema key, export or closed-set member is added, nothing previously admitted is refused, and no authored document changes meaning.
+
+`DEFAULT_METADATA_TYPE_REGISTRY` has declared `datasource` with `allowRuntimeCreate: true` since ADR-0015's Addendum, and no rule named it in `runtimeTypes` — so the gate filtered a datasource write out before it consulted the stack-key table, and the write built no snapshot and ran no rule at all. It is the ADR-0049 declared-not-enforced shape, missed by the census that graded ten sibling types because its registry entry is the only multi-line one and a single-line reader of the registry cannot see it.
+
+- **The group was measured, not inherited**, because this type sat outside the ten the ruling graded. **Retirement is refuted**: that arm is for a declaration with no stack collection to create into, and `datasources` is a first-class collection with a live runtime create path. **The `skill` hold-out is refuted too**, which is the half that decided it — `skill` stayed out because its bridge resolves references into `stack.tools` / `stack.actions`, collections the door's snapshot does not carry, so the door reached a verdict the whole stack does not share. This rule resolves into nothing: it judges each written item's own top-level keys against that type's liveness ledger, and the door's verdict and the whole-stack verdict are pinned as the identical value.
+- **⚠️ Dispatched and silent, on purpose.** `packages/spec/liveness/datasource.json` carries 0 warn keys, so no datasource document can be advised at this door today — the `email_template` / `mapping` end state exactly, under the same fence: the wiring is the whole deliverable and ⛔ no ledger-population work rides with it. The day a datasource property earns an `authorWarn` row the door lights up with no second edit. The silence is pinned beside a lit control on the same instrument in the same process, so it can never be read as a broken dispatch or an unresolvable ledger directory.
+- **The stack key is proved behaviourally**, which its two ledger-driven siblings could not manage: `runtime-gate.datasource-writes.test.ts` drives the real rule through its ledger-directory seam over a stack built at `stackKeyForType('datasource')` itself, with the wrong-key leg asserted beside it, so the `seed: 'data'` failure shape — a mapping onto a collection nothing reads — reds a case here rather than riding on one string assertion.
+- **Nothing else widened.** A datasource write reaches this one rule and no reference-integrity member; `translation`, `tool`, `doc`, `external_catalog` and `skill` keep their empty rosters, each awaiting its own reading or retirement.
@@ -1414,8 +1414,30 @@ export const AUTHORING_RULES: readonly AuthoringRule[] = [
     // the whole deliverable»). `runtime-gate.inert-type-writes.test.ts` pins
     // both halves — that the rule is dispatched, and that it is silent — so
     // the day a ledger row lands the door lights up with no second edit here.
+    //
+    // [#19568] `datasource` joins them, on a reading rather than by
+    // inheritance: it was outside the ten types the ADR-0049 ruling graded, so
+    // its group had to be measured. Both arms the card offered were tested
+    // against the ruling's own criteria. RETIREMENT is refuted — that arm is
+    // for a declaration 「no stack collection exists to create into」, and
+    // `ObjectStackDefinitionSchema.datasources` is a first-class collection a
+    // Studio/REST/MCP author really mints into (ADR-0015 Addendum,
+    // `origin: 'runtime'`). The `skill` HOLD-OUT is refuted too, and that is
+    // the one worth stating: `skill` was held back because
+    // `validateAiToolReferences` resolves into `stack.tools` / `stack.actions`
+    // — collections the door's snapshot does not carry — so the door's verdict
+    // differed from the whole-stack verdict and wiring it would have shipped a
+    // FALSE advisory into Studio. This rule resolves into nothing: it judges
+    // each written item's own top-level keys against its type's ledger, so the
+    // door's verdict and the whole-stack verdict are the same value by
+    // construction (pinned as a door-vs-stack comparison, not as an argument).
+    //
+    // ⚠️ MEASURED, same instrument, same run as the two above:
+    // `packages/spec/liveness/datasource.json` is 12 props / 0 warn keys, so
+    // this third type is dispatched and silent exactly as they are. The fence
+    // is inherited with the shape: ⛔ no ledger-population work, zero pull.
     surfaces: CLI_AND_RUNTIME,
-    runtimeTypes: ['email_template', 'mapping'],
+    runtimeTypes: ['email_template', 'mapping', 'datasource'],
     run: (stack) =>
       lintLivenessProperties(stack).map((f) => ({
         severity: 'warning' as const,