test: pin the validator's symlinked-directory gate

[hivecommons-hive]

Test Improvement

Pins scripts/validate-architectures.mjs's handling of a symlinked directory under
docs/architectures/ — the arm #1242 added one day ago and that no test at validator
level reaches.

listArchitecturePages() fails closed on such a link because
@docusaurus/plugin-content-docs globs docs with fast-glob's default
followSymbolicLinks: true, so every page beneath the link ships at
/architectures/<link>/... without reaching the active-content gate.
tests/architecture-pages.test.mjs:147 pins that inside the library; the validator's own
symlink test (tests/validate-architectures.test.mjs:340) uses a page-named link,
which reaches the same irregular loop through the page-extension arm and therefore
holds it open whatever the directory arm does.

The mutation is the proof, not an illustration

Filtering the validator's irregular loop to page-named entries —

for (const page of irregular) {
  if (!/\.mdx?$/.test(page)) continue;

— leaves tests/architecture-pages.test.mjs and tests/validate-architectures.test.mjs
at 51/51 pass, while the hole #1242 closed reopens end to end. With this PR the first
new test fails on it. Region coverage cannot see the mutation either way: the page-named
case already executes the loop body, so the file stays at 100.00% lines / 100.00%
regions.

Files and functions claimed

• tests/validate-architectures.test.mjs — two appended tests only. Disjoint from every
  open hold-gated PR: fix(security): treat a slashless http: value as a remote authority #1249 (tests/svg-active-content.test.mjs), fix(security): reject remote image destinations in imported MDX pages #1255
  (tests/mdx-active-content.test.mjs), fix(security): reduce a script-capable image destination to alt text #1264
  (tests/architecture-content-clean-markdown.test.mjs), test(coverage): ratchet the per-file harness region floor 93 -> 97 #1250 (package.json,
  tests/coverage-gate-thresholds.test.mjs), test: pin sourceBoundaryOffsets short-segment guard and multi-boundary sort #1252, test: pin the uri-safety classifier's own contract #1262, test(e2e): drive the contributor membership filter in a browser #1266, test: pin each e2e data overlay's effect on the validator that gates its file #1269. No production
  file is touched.

Two tests, both at validator level:

1. a symlinked directory of pages exits non-zero and is reported at the link's own path
   with the message the validator carries, and no page beneath the link is named —
   reported, never followed;
2. the complement — a link resolving to neither a page nor a directory still passes, so a
   future tightening to "every symlink is an error" cannot start failing checkouts that
   publish nothing through the link without a test objecting.

Verification

• TZ=UTC node --test tests/validate-architectures.test.mjs — 31/31 pass.
• npm run test:unit:coverage:check — exit 0; src files 100.00 | 100.00,
  harness files 100.00 | 99.19, all files 99.65 | 96.13. Node v26.10.0, TZ=UTC,
  locally at 365e11f.
• npx prettier --check tests/validate-architectures.test.mjs — clean.

Related Issue

Closes #1272

---

Filed by quality agent (hold-gated mode). Human review required.

— hive: agent=quality backend=copilot model=claude-opus-5 copilot=1.0.88

[hivecommons-hive]

Important

Held for human review by the hive's ACMM level gate.

This PR was opened by the "quality" agent while Hive policy required a human checkpoint for that agent. Non-outreach agents are held at ACMM L3–L5; the outreach agent is always held because it publishes project-facing communication.

Hive will keep the hold label until a human removes it. Operators can make a deliberate one-off release during an ACMM level change with release_level_holds=true, but level changes never release this hold automatically.