refactor(skills): retrofit the corpus to the ADR-0020 context contract (#129)

Retrofits all 39 skills to ADR-0020's description/body context contract, then fixes what six rounds of independent review found in that retrofit — including four ways the hot gate itself failed open.

Closes #99, #107, #108, #110, #111, #114, #115, #120.

## The retrofit (waves 1-5)

| | Start | Now |
|---|---|---|
| Description FAILs (>400 chars) | 26 | **0** |
| Body FAILs (>900 words, body-only) | 9 | **0** |
| Dangling routing targets | 2 | **0** |
| `Kyberforge.CompositionNote` | 10 | **0** |
| Preload tax | 21,005 chars | **~10,500** |

Under the 12,000-char success criterion. Per-wave detail is on #99.

## The review fixes

**The gate failed open four ways, three of them found after the retrofit shipped.** An unrecognised follower token made a dangling target vanish. A skill directory with no `SKILL.md` resolved as a valid target, so a commit could be green locally and red in a fresh clone — three existing fixtures were relying on that, one of which made the install-leak A/B pass vacuously. Then the free-standing `/name` sweep turned out to be gated on the sentence carrying a boundary marker, so route notation in any other sentence was invisible — not an ERROR, not a SUGGESTION, not an INFO — which left the documented "`/name` always blocks" promise false from a second direction. All four fixed and pinned.

**Two checks were silently not running.** `validate-provenance.sh` checks 7-8 were dead across nine skills. Waking them exposed a deeper problem: they assume `Research doc:` names a source index, but 30 of 121 entries point at topic content documents, so every new check-7 INFO was a false positive and check 8 was saved from a false-FAIL flood only by an *unannounced* skip. Checks 7/8 are now scoped to source indexes and every skip announces itself (#121).

**The retrofit's own anti-goal, four times.** ADR-0020 warns that a blunt gate gets satisfied by deleting content rather than relocating it. `diagnose` and `skill-audit` relocated prose and then read it unconditionally; `prototype` and `vale-config` deleted rules outright that survived nowhere. All four addressed.

## Verification

- `bash tests/run-tests.sh --strict` — 24 suites, 0 skipped, 0 failed
- `bash tests/run-bats.sh` — 325 tests, 0 failures
- `pre-commit run --all-files` — 17/17
- `pre-commit run --hook-stage pre-push --all-files` — 16/16, with `apm marketplace check` and `apm pack --check-clean` run against the remote, not skipped
- `scripts/skill-size-check.sh` over all 39 skills — rc 0, 0 ERROR/FAIL, SUGGESTION-only
- Preload tax measured at **10,498 chars**, max description 390 — both inside budget
- Every new test proven non-vacuous by a deliberate mutation of the behaviour it covers

**Per-commit sync, stated accurately:** the ten commits from the latest review round each pass `check-plugin-content-sync` in isolation, verified by checking each out in a detached worktree with a clean between. The earlier gitea window (`dfacf05..bedbd1d`, nine commits) does **not** — its mirror was regenerated in one batch at `bbc7300`. An earlier revision of this description claimed the property held for every commit; it does not, and a bisect through that window lands on a red commit. **Squash-merge** to collapse it, or accept that this range is not bisectable.

## Version bump

Six plugins and the catalog take a **patch**, not a minor. The branch is **89 commits — 40 `fix` / 30 `refactor` / 12 `docs` / 5 `chore` / 2 `test` — zero `feat`, zero `!`, zero `BREAKING CHANGE`** — and adds no skill, agent, command or hook. (Two earlier revisions of this section cited a stale histogram, most recently 78 commits; the figures above are measured at HEAD.) Both rules this repo ships (`forge/references/version-bump.md`, landing in this PR, and `git-commits/references/conventional-commits-spec.md`) make that a patch, and the catalog set is unchanged at 7 entries.

Not settled by that: four published files were removed from the installed tree, three moved, and `caveman` gained `disable-model-invocation`, retiring its old triggers. Under a strict reading those are major-class and currently ship under `refactor:` with no marker. Whether the deployed skill surface is a public contract is written down nowhere — worth deciding, but it outlives this PR.

## Deliberately not in scope

#112 (cherry-pick ownership, now resolved in favour of `git-commits`), #113 (`rtk git` normalisation), #116 (research fan-out), #101 (audit-skill merge), #122 (non-spec skill-root files), #123 (no PRD producer) stay open. #117 is the one worth reading: the contract's remedy is to move prose into `references/`, which is exactly where neither the size gate nor Vale looks — and the blind spot is wider than #117 currently records, since there is no root `.vale.ini` at all, so every ADR, `CONTEXT.md` and `README.md` is unlinted too.

That blind spot let this branch carry two `level: error` `Kyberforge.SentenceOpenerThereIs` violations into `references/` files it created — `provider-adapter-author/references/provider-matrix.md:31` and `agent-audit/references/finding-criteria.md:95`. Both are reworded in `afadaae`, confirmed by routing each file through the audit's own `vale-wrap.sh` (1 error each before, 0 after). Five further occurrences sit in `references/` files already on `main`; those are the pre-existing corpus and stay with #117, which is the real fix.

Also unfixed and not this PR's: `apm install` appends a duplicate `SessionStart` entry to `.claude/settings.json`, so a fresh clone cannot get pre-push green without an edit AGENTS.md warns against. Reproduces identically on `main`.

Co-authored-by: Defame1297 <gitea@rkdr.net>
Reviewed-on: https://git.dev.rkdr.net/Defame1297/holocron/pulls/129
Co-authored-by: Claude Code AI - Gitea MCP <claude@noreply.git.dev.rkdr.net>
Co-committed-by: Claude Code AI - Gitea MCP <claude@noreply.git.dev.rkdr.net>

plugins/core/skills/provider-adapter-author/SKILL.md

@@ -1,43 +1,41 @@
 ---
 name: provider-adapter-author
 description: >
-  Use when the user wants to convert a provider-specific AI instruction file
-  (CLAUDE.md, .cursor/rules/*.mdc, copilot-instructions.md, etc.) into a
-  thin adapter that defers to a repo's AGENTS.md — e.g. "reduce duplication
-  between CLAUDE.md and AGENTS.md", "make CLAUDE.md just import AGENTS.md"
-  — even if the pattern isn't named explicitly. Also invoke when
-  agentsmd-author detects an existing provider file overlapping with
-  AGENTS.md it just wrote. Detects redundant content in a provider file
-  relative to AGENTS.md and rewrites it down to a minimal reference (an
-  `@AGENTS.md`-style import where supported, or a text pointer otherwise)
-  plus genuinely provider-specific additions. Self-validates via a bundled
-  deterministic script before finishing. Do not use to write or audit
-  AGENTS.md itself — use agentsmd-author or agentsmd-audit.
+  Use when a provider file (CLAUDE.md, .cursor rules, copilot-instructions)
+  duplicating the repo's AGENTS.md should be cut to a thin adapter — "make
+  CLAUDE.md just import AGENTS.md".
+  Not writing the AGENTS file -> `agentsmd-author`.
+  Not auditing the AGENTS file -> `agentsmd-audit`.
 allowed-tools: Bash Read Edit Write
 metadata:
   category: docs
   source_keys:
     - adr-0002-0003-two-tier-claude-md
-  version: "0.1.0"
+  version: "0.1.1"
 ---
 
 ## Gotchas
 
-- Not every provider supports cross-file imports. Claude Code does — a `CLAUDE.md` can consist of nothing but one or more `@path` lines (e.g. `@AGENTS.md`), with no other content required. Cursor's `.cursor/rules/*.mdc` and GitHub Copilot's `copilot-instructions.md` have no native import mechanism as of current tooling — for those, "thin" means a short text pointer to AGENTS.md plus only what that tool actually needs, not a literal import line. Pass `--no-import-syntax` to `scripts/validate-adapter.sh` for these providers.
-- This skill never creates or edits `AGENTS.md` itself. If the target repo has no `AGENTS.md` yet, stop and point the user to `agentsmd-author` first — there's nothing to adapt to.
-- Only strip content from the provider file that's genuinely redundant with AGENTS.md. Provider-specific material (IDE settings, tool-only syntax, model-specific instructions) stays — the goal is thin, not empty.
-- Works standalone or composed-into by `agentsmd-author` — behave identically either way; don't assume a caller skill exists.
+- Assume a provider has no cross-file import mechanism until you have confirmed it has one. Claude Code is the exception, not the rule: a `CLAUDE.md` may consist of nothing but `@path` lines, while the same `@AGENTS.md` line in a Cursor rule or a Copilot instructions file is inert text no tool resolves. Pass `--no-import-syntax` to `scripts/validate-adapter.sh` for those providers.
+
+- Works standalone or composed-into by `agentsmd-author` — behave identically either way; do not assume a caller skill exists. Detect the provider file, confirm `AGENTS.md`, and run the closeout validator yourself in both cases (`references/provider-matrix.md`).
 
 ## Step 1 — Detect
 
-Look for known provider instruction files in the target repo: `CLAUDE.md` (repo root, and any deployed copies), `.cursor/rules/*.mdc`, `.github/copilot-instructions.md`, and similar tool-specific files. Confirm `AGENTS.md` exists at the repo root — if not, stop and tell the user to run `agentsmd-author` first.
+Find the provider instruction file to convert. Before searching, read `references/provider-matrix.md` — skip it only when the target is already a known root `CLAUDE.md`, which is the common case.
+
+Then confirm `AGENTS.md` exists at the repo root. If it does not, stop and tell the user to run `agentsmd-author` first — there is nothing to adapt to.
 
 ## Step 2 — Diff and rewrite
 
 Read the provider file and `AGENTS.md` side by side. Separate the provider file's content into two buckets: lines that restate what `AGENTS.md` already owns (universal rules, conventions, project overview) versus lines that are genuinely provider-specific (tool syntax, IDE behavior, model-specific instructions). Rewrite the provider file:
 
-- **Providers with import syntax** (Claude Code): replace the redundant bucket with an `@AGENTS.md` (or correct relative path) import line, keep the provider-specific bucket below it.
-- **Providers without import syntax** (Cursor, Copilot, etc.): replace the redundant bucket with a short pointer sentence mentioning `AGENTS.md`, keep the provider-specific bucket.
+- **Providers with import syntax** (Claude Code): replace the redundant bucket with an `@AGENTS.md` (or correct relative path) import on a line of its own, keep the provider-specific bucket below it. An import folded into a sentence is not the thin-adapter shape and `scripts/validate-adapter.sh` will not credit it — nor one inside a code fence, an indented block, or an HTML comment, nor one whose path does not resolve to a real, non-empty file on disk.
+- **Providers without import syntax** (Cursor, Copilot, etc.): replace the redundant bucket with a short sentence pointing at `AGENTS.md` ("See AGENTS.md at the repo root for ..."), keep the provider-specific bucket. A bare or negated mention is not a pointer and will not be credited.
+
+The provider file is the only file this skill ever writes. Never create or edit `AGENTS.md` — not in this step, not in any step, whatever the payoff looks like.
+
+Strip only what is genuinely redundant. Provider-specific material stays even when it is short — the goal is thin, not empty.
 
 ## Step 3 — Self-validate
 
@@ -47,7 +45,7 @@ Run the bundled check before finishing — this is the skill's own closeout gate
 bash scripts/validate-adapter.sh [--no-import-syntax] [--max-lines N] <adapter-file> <agents-md-file>
 ```
 
-Fix any `FAIL` and re-run until it exits `0`.
+Fix any `FAIL` by editing the provider file, and re-run until it exits `0`. Exits `2` and `3` are not `FAIL`s and nothing was graded under either, so neither is a reason to touch the adapter: `2` means the invocation or the input is wrong (a bad, missing, or extra argument, an unknown option, or a file that is not UTF-8), and `3` means a named file exists but could not be read.
 
 ## Step 4 — Report