docs(adr): record that Research doc names one Research registry

ADR-0028 records the grammar decided for #121 and the alternatives
rejected at each step: what `Research doc:` refers to, how an entry with
no registry declares that (`none` plus `Basis:`), the FAIL and INFO
tiers, the corpus-wide sweep gate, parser parity, retiring check 8, the
`(removed in <sha>)` escape for Basis paths, and removing the lint entry
that had no verifiable basis.

Add the Research registry term to CONTEXT.md, since "registry" had no
definition and "research doc" was being used for both the registry and
the topic docs it digests.

Refs: #121
ADR: 0028
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EGHFJextYtVQseaHPDDhxB

CONTEXT.md

@@ -81,6 +81,13 @@ topic docs and a `sources.md`; the author skill records which sources informed w
 and internally consistent.
 _Avoid_: sources, citations, attribution
 
+**Research registry**:
+A plugin's research `sources.md` (e.g. `plugins/git/docs/research/docs/git/sources.md`), whose `## H2`
+headings are the source slugs. A skill's `Research doc:` field names exactly one, and
+`factory-audit` resolves each entry's slug against it. An entry with no registry declares
+`Research doc: none` and names what it was actually drawn from in `Basis:`.
+_Avoid_: research doc, sources file, topic doc (a topic doc is a digest of sources, not the registry)
+
 ### Governance
 
 **HITL** (human-in-the-loop):

docs/adr/0028-research-doc-names-the-research-registry.md

@@ -0,0 +1,136 @@
+# `Research doc:` names one Research registry; entries without one declare `none` and a `Basis:`
+
+**Status: accepted (2026-09-21).** Resolves #121. Extends ADR-0004's INFO level: it keeps INFO for
+the case where a check cannot run and promotes the case where it ran and found a mismatch.
+
+Each entry in a skill's `references/sources.md` carries a `Research doc:` field. The spec
+(`skill-author/references/create.md`) says it names the plugin's research `sources.md`, the file
+whose `## H2` headings are the source slugs. The corpus did something else: 29 of 30 mismatched
+entries pointed at a research topic doc annotated `(whole-document reference)`, and 6 values were not
+a single path (comma-separated lists and shell brace expansion, plus a semicolon pair in
+`gitea-releases`). Checks 7 and 8 of `validate-provenance.sh` look the slug up as an H2 in the named
+file, so 36 entries reported INFO and nothing failed. Measured by running the script over all 39 skill
+directories, since nothing else runs it over the corpus.
+
+We decided that `Research doc:` names exactly one **Research registry** (the term is in
+`CONTEXT.md`), as the spec always said. Slug-to-H2 lookup in the registry is the only provenance link
+that can be verified deterministically; a topic doc has no per-source H2 to check against. A link to
+the topic doc that digested a source stays as free-text annotation and is not checked.
+
+## Considered options
+
+**Q1 — what `Research doc:` refers to.**
+
+- **(a) The Research registry (chosen).** Check 7 stays as designed (check 8 is retired, see Q6); the
+  29 entries repoint mechanically.
+- **(b) The topic docs a source fed into (rejected).** Matches what the authors wrote, and is arguably
+  the more useful pointer for a reader. Rejected because it changes the spec and the checker, and the
+  slug check has nothing to run against.
+- **(c) Both, as two fields (rejected).** Doubles the schema for a link nobody gates on.
+
+**Q2 — how an entry with no registry declares that honestly.**
+
+- **(a) `Research doc: none` plus a `Basis:` field (chosen).** `Basis:` takes repeated bullets of
+  repo paths (ADRs, `core/instructions/*.md`, a live example) and is checked for existence only.
+  `research_doc_is_none` already parses `none`, and `git-workflow` already writes it. Same shape as
+  #111: there was no honest way to declare the truthful thing.
+- **(b) A non-corpus path stays legal in `Research doc:` (rejected).** Leaves one field meaning two
+  things depending on its value, and the INFO it produces can never be cleared.
+- **(c) Move non-corpus entries out of `sources.md` (rejected).** A larger restructure than the
+  issue warrants.
+
+Lists are not needed under Q1(a): the four `pc-author` and `pc-run` brace expansions are one
+registry, and the `gitea-releases` pair collapses to one registry. Brace expansion and semicolon
+pairs are rejected outright, since nothing expands them in a markdown field.
+
+**Q3 — tier once the grammar is settled.**
+
+- **(b) FAIL when the path resolves and check 7 finds a mismatch; INFO when the path does not
+  resolve (chosen).** Check 8 is not part of this: see Q6. A topic doc in `Research doc:` is now
+  simply wrong and is a FAIL. An
+  unresolvable path stays INFO because `skill-file-structure.md` treats `sources.md` pointers as
+  development-time, and a deployed copy of a skill outside this repo will not have the research docs.
+  This repo's own corpus is audited from the authoring source, where every path resolves.
+- **(a) Everything stays INFO (rejected).** Under ADR-0004 INFO implies no action, which is how 36
+  mismatches went unnoticed.
+- **(c) Everything FAIL (rejected).** Fails a correctly-provenanced skill audited from a deployed
+  copy, which the file-structure exemption exists to prevent.
+
+**Q6 — what happens to check 8.** Found unsatisfiable during the migration, after Q3 was decided.
+Check 8 requires every `extracted` slug in the research doc to appear in the skill's `sources.md`.
+That worked while entries pointed at topic docs, and was dormant. Under Q1(a) the named file is a
+registry shared by many skills (`git/sources.md` backs seven), and nothing ties a registry slug to one
+skill, so every skill would fail permanently. The direction that matters, that each slug a skill lists
+exists in the registry, is already check 7.
+
+- **(a) Retire check 8 (chosen).** Check 7 is the FAIL. Under registry semantics check 8 has no
+  satisfiable meaning.
+- **(b) Keep it as an INFO (rejected).** Recreates the noise ADR-0004 warns about: an observation with
+  no action that every skill emits forever.
+- **(c) Redefine it as a registry-side coverage report (rejected for now).** "Registry slugs that no
+  skill uses" is a coherent check, but it is a report across all skills and separate work from this
+  issue.
+
+**Q7 — `Basis:` paths that no longer exist.** Found in the same migration: `git-commits` and
+`git-workflow` cite `core/instructions/git.md` and `commits.md`, deleted in `5deed07`. An existence
+check on every `Basis:` bullet would fail them.
+
+- **(a) A bullet annotated `(removed in <sha>)` skips the existence check (chosen).** The check stays
+  for live paths, which is what catches a renamed ADR, and deletion becomes an explicit, auditable
+  annotation. Weakness: the annotation can be written on any bullet to avoid the check. Verifying the
+  sha with `git cat-file -e` would close that, and was left out as over-engineering for three bullets.
+- **(b) `Basis:` becomes free prose with no existence check (rejected).** Gives up the one check that
+  catches a renamed or moved ADR.
+- **(c) Drop those `Basis:` lines and keep `none` with a prose reason (rejected).** Loses the
+  machine-readable record of what the entry was drawn from.
+
+Form: one path per bullet, `- **Basis:** <path>` repeated, not a header with sub-bullets.
+
+**Q8 — the `lint` entry with no verifiable basis.** `house-vale-3-15-2-repro` in `vale-config` and
+`vale-run` said `none` and claimed six behaviours were "established by running it against purpose-built
+fixtures in this repo". No such fixture or test exists in the tree or in history: the entry was added
+in `d1afdbe` with no test files, and the only vale test ever deleted (`4de5b6b`) guards an unrelated
+`E100`. Under Q2 it FAILed for a missing `Basis:`.
+
+- **(e) Remove the entry and its `source_keys` citations (chosen).** The stated basis was false, so
+  there is nothing honest to declare. The behavioural rules stay in the skills; only the provenance
+  claim goes. The gate needs no allowlist.
+- **(a) `Basis: tests/test-vale-wrap.sh` (rejected).** Backs about one of six claims and overstates the
+  rest.
+- **(b) Commit reproduction fixtures (rejected for now).** The right fix if the behaviours matter, but
+  separate work from this issue.
+- **(c) Allow `none` without `Basis:` for "house-verified" entries (rejected).** Reopens Q2 and gives
+  an escape hatch for unverified claims.
+- **(d) Keep the entry and allowlist the two skills in the gate (rejected).** Keeps a false claim in
+  place and adds a list that can rot.
+
+`configuration-reference.md` still says its rows were "reproduced against Vale 3.15.2"; that wording
+now has no provenance entry behind it and is left for a separate decision.
+
+**Q4 — enforcement.** A corpus-wide sweep gate lands in the same change: a test or pre-push hook that
+runs `validate-provenance.sh` over every `plugins/*/.apm/skills/*/` and fails on any FAIL. Deferring it
+was rejected because without a caller the FAIL tier is inert; nothing but `check-scope-walkup-sync.sh`
+(on fixtures) invokes the validator today.
+
+**Q5 — parser parity.** `parse_status` and `parse_research_doc` accept the bullet spelling
+(`- **Status:**`) as `parse_contributing_files` already does, with a regression test. Included because
+it is the same failure shape as #111 and #118 (a parser returns "nothing found", the caller reads it as
+"nothing declared"), sits in the same file, and `gitea-releases` already writes the unhyphenated form.
+
+## Consequences
+
+- About 40 `references/sources.md` entries migrate: roughly 30 repoint from a topic doc to the registry,
+  about 4 move to `Research doc: none` with a `Basis:` list (`provider-adapter-author`,
+  `git-commits` `org-commit-conventions`, `agentsmd-audit` `governance-secrets-hard-prohibition`,
+  `git-workflow`), and the `gitea-releases` pair collapses to one path.
+- `Basis:` is a new field: `create.md` step 6, `skill-file-structure.md` and the validator's usage text
+  must state it, and the validator must check that each listed path exists, except a bullet annotated
+  `(removed in <sha>)`. Each `Basis:` path is one bullet.
+- Check 7 gains a FAIL tier for resolved-path mismatches. INFO remains for a path that does not
+  resolve. A topic doc named in `Research doc:` is no longer legal: it is a FAIL, since a topic doc has
+  no per-source `## H2` to check the slug against.
+- Check 8 is retired: remove it from `lib-provenance-skill.sh`, its usage text and the tests, and drop
+  its mention from `skill-file-structure.md` and `create.md` where present.
+- The corpus-wide sweep is a new gate: register it in `docs/spec/gates.md` and
+  `.pre-commit-config.yaml`. The corpus must be migrated in the same change or the suite goes red.
+- Reversing this means re-migrating the same entries, which is why it is recorded.