docs(carriers): record the runtime-closure gate slice

docs/design/context-carriers.tdd.md

@@ -76,3 +76,17 @@ Lower-priority review suggestions remain explicit follow-ups: failing projection
 ## Claims deliberately left unobserved
 
 Native discovery, exact native exclusions, invocation, executable-mode needs, workflow outcomes, activation, hook consent, rollback, automatic routing and actual token savings still require their own gates. Schema validation checks shape; it cannot certify supplied artifact semantics. The independently compiled fixture checks exact layout, selection, file set and bytes. It uses a trusted private temporary parent and does not certify an arbitrary-destination transaction writer against hostile concurrent mutation. No native provider, model, container or VM was launched, and no package was published.
+
+## October 8 static runtime-closure gate
+
+Date: October 8, 2026. `scripts/ci/validate-carrier-closure.js` now plans every supported carrier layout for both Lean and Full and checks that each planned JavaScript file's relative `require`/`import` specifiers resolve to a file the same carrier plans. The static require-graph extraction technique is adapted from community PR #2788; that work's staged load smoke, which materializes a carrier and actually loads entry scripts from inside it, is deliberately not ported, and neither is command pruning. Both wait for carrier scope to widen beyond skills.
+
+RED: `tests/scripts/validate-carrier-closure.test.js` added 8 `node:test` cases; all 8 failed, seven because the validator module was absent and the eighth because the npm gate was unregistered. GREEN: all 8 pass. The supported-layout list is derived by planning every registry target and keeping the ones that return a layout, so a new layout is picked up without editing the validator.
+
+Against the real registry the gate reports 5 supported layouts of 16 declared targets — `claude-plugin@1`, `codex-plugin@1`, `pi-package@1`, `opencode-project@1` and `cursor-project@1` — giving 10 projections and 2,941 planned files. 65 of those planned files are JavaScript: 13 per Full projection and none in Lean. They declare 35 relative specifiers, all 35 resolving inside their own carrier; every one is a sibling `./shared.mjs` import within `skills/ck`. The validator finds zero escapes and zero dynamic requires.
+
+Zero escapes is the expected result and not evidence the check is idle. Carriers are skill-only today, so no skill script has a reason to reach past its own directory. The gate exists so that the first command, agent, rule or hook admitted into carrier scope cannot silently ship a script reference that the projection does not contain. Detection is pinned by fixtures rather than by the live inventory: a planted skill script requiring `../../../../../scripts/lib/context-profile-support` fails as `outside-carrier-tree` in all five layouts and names the specifier, a planted sibling-skill reference fails as `unplanned-target`, a planted non-literal `require` warns without failing, and a `require` shape quoted inside a string literal produces neither.
+
+Limits. Nothing is executed; the check reads bytes and resolves paths. Bare specifiers are out of scope, so a skill script that depends on an npm package or a Node builtin is not examined for availability inside a carrier. Resolution assumes CommonJS extension candidates for `.js` and `.cjs` and exact specifiers for `.mjs`; it does not model conditional exports, a nested `package.json` type field, or import maps. A non-literal `require` is reported, not resolved, so a carrier can still fail at load time through a path computed at runtime. Native discovery, executable mode and actual loading remain unobserved, exactly as before.
+
+Focused verification: 22 carrier cases, 12 compiler cases, 8 closure cases, 3 CI cases and 2 publish-surface cases pass with zero failures or skips. ESLint passes on the validator and the new test. The validator is CI-only and stays out of the packed surface, matching `scripts/ci/validate-context-profiles.js`.