ARCHITECTURE.md links to docs/adr/0001-metadata-service-architecture.md, deleted 2026-02-11 — the link 404s #6733

Found while implementing #6634 (the ADR-0079 dangling-pointer fix); out of that PR's scope, filed unassigned.

The fact

ARCHITECTURE.md:653 carries a markdown link, not a bare mention:

- [ADR-0001: Metadata Service Architecture](docs/adr/0001-metadata-service-architecture.md) - Explains why both ObjectQL and MetadataPlugin can provide metadata service and how they work together

That file was deleted on 2026-02-11 in 9da8e3e72 ("feat(docs): add comprehensive analysis of Permission Protocol...") together with docs/adr/0002-database-driven-metadata-storage.md and docs/adr/README.md. Verified against the full history (the working clone is shallow by default — this needs git fetch --deepen before git log --diff-filter=D -- 'docs/adr/*' says anything true).

So a reader of ARCHITECTURE.md who follows the repo's most prominent pointer to "why both ObjectQL and MetadataPlugin can provide metadata service" reaches a 404.

Why it is not fixed in #6634's PR

Different defect, different fix. #6634 is about a number cited with no record; this is a link to a path that was removed, and fixing it means deciding what the correct target is (the explanation may have moved into another ADR, or may need re-homing) — a docs judgement, not a mechanical repoint.

The other two ADR-0001 sites in the tree are fine and should not be touched:

• docs/adr/0002-environment-database-isolation.md:122 — "already discarded in v3.4's ADR-0001", legitimate history.
• examples/app-showcase/src/ui/pages/{project-detail,project-workspace}.page.ts — these cite ObjectUI ADR-0001, a different repo's registry.

Interaction with #6634's gate widening

The PR for #6634 extends check:adr-anchors to assert every cited ADR number resolves, and puts 0001 on a shrink-only UNRESOLVED_ADR_CITATIONS allowlist (deleted record, cited as history). The entry's comment names this broken link explicitly and says the allowlist does not bless it — the allowlist is per-number and cannot distinguish "history" from "broken link" at that granularity. Fixing this issue does not require removing the allowlist entry (ADR-0002's historical mention keeps it earning its place).

Note .github/workflows/check-links.yml (advisory lane, repo-internal links, restored 2026-08-07) would plausibly have caught this — worth checking why it does not, but that file is under active work elsewhere and is not part of this report.