fix(apm): commit the hook ownership sidecar so fresh installs stay idempotent

apm recognises its own settings.json hook entries only through the
.claude/apm-hooks.json sidecar. With the sidecar gitignored, apm install
in a fresh clone keeps the committed SessionStart entry as user-owned and
appends a duplicate, so apm audit --ci reports drift and the apm-audit-ci
pre-push hook fails. Reproduced on main and this branch with apm 0.28.0.

Commit the sidecar in apm's exact serialisation, exclude it from
pretty-format-json alongside settings.json, and record the correction
in ADR-0019.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.claude/apm-hooks.json

@@ -0,0 +1,15 @@
+{
+  "SessionStart": [
+    {
+      "matcher": "startup",
+      "hooks": [
+        {
+          "type": "command",
+          "command": "\"${CLAUDE_PROJECT_DIR}/.claude/hooks/kyberforge/.apm/hooks/check-apm-current.sh\"",
+          "timeout": 380
+        }
+      ],
+      "_apm_source": "Defame1297/holocron/plugins/kyberforge"
+    }
+  ]
+}

.gitignore

@@ -40,11 +40,11 @@ apm_modules/
 /.mcp.json
 
 # APM hook deployment output — `apm install` copies each package's referenced
-# hook scripts here and tracks its own settings.json entries in the sidecar.
-# Regenerated on every install; the authoring source is
-# plugins/<name>/.apm/hooks/ (ADR-0019).
+# hook scripts here. Regenerated on every install; the authoring source is
+# plugins/<name>/.apm/hooks/ (ADR-0019). The .claude/apm-hooks.json ownership
+# sidecar is committed, not ignored: without it a fresh clone's install cannot
+# claim the committed settings.json entry and duplicates it (ADR-0019).
 .claude/hooks/
-.claude/apm-hooks.json
 
 # `apm pack` bundle output. The pre-push gate runs pack with --dry-run, so this
 # only appears after a bare `apm pack` during a release; it is not repo content.

.pre-commit-config.yaml

@@ -44,8 +44,9 @@ repos:
         # alternations went with them: `check-useless-excludes` fails on a
         # pattern that matches no file.
         #
-        # `.claude/settings.json` is the second and last alternation, and it is
-        # the only one here for a reason other than "generated manifest":
+        # `.claude/settings.json` and its `.claude/apm-hooks.json` ownership
+        # sidecar are the last two alternations, and they are the only ones
+        # here for a reason other than "generated manifest":
         # apm OWNS that file (ADR-0018, ADR-0019), and
         # `apm audit --ci` replays the install into a scratch tree and diffs
         # the result byte-for-byte. `pretty-format-json` sorts object keys
@@ -56,8 +57,11 @@ repos:
         # as permanent drift on a file with no git diff -- exactly what
         # happened when the SessionStart hook first landed in 2e395a4.
         # Re-running `apm install` fixes the file; leaving it in scope here
-        # would re-break it on the very commit that carries the fix.
-        exclude: '^(\.claude-plugin/marketplace\.json|\.claude/settings\.json)$'
+        # would re-break it on the very commit that carries the fix. The
+        # sidecar is committed so a fresh clone's install can claim the
+        # settings entry instead of duplicating it (ADR-0019, 2026-09-16
+        # correction), and it is apm output under the same byte-for-byte replay.
+        exclude: '^(\.claude-plugin/marketplace\.json|\.claude/(settings|apm-hooks)\.json)$'
       - id: check-yaml
         stages: ['pre-commit']
       - id: trailing-whitespace

docs/adr/0019-session-start-hook-keeps-the-apm-install-current.md

@@ -187,6 +187,16 @@ settings file remains committed, now with apm-generated content in it. ADR-0018'
 committed content is exactly `{"hooks": {}}` is superseded on that point only — the rule it was
 protecting, that nothing repo-authored goes in that file, is unchanged.
 
+> **Correction (2026-09-16) — the sidecar is committed, not ignored.** apm keeps no ownership marker
+> inside `settings.json`; it recognises its own entries by matching them against
+> `.claude/apm-hooks.json`, then replaces them. With the sidecar gitignored, a fresh clone holds the
+> committed `SessionStart` entry but no sidecar, so `apm install` treats the entry as user-owned,
+> keeps it, and adds its own identical copy. `apm audit --ci` then reports `settings.json` drift and
+> the `apm-audit-ci` pre-push hook fails. Reproduced on `main` (`a712f2c`) and on this branch with
+> apm 0.28.0; committing the sidecar makes the install idempotent and the audit pass. The sidecar
+> is apm output like the settings entry it describes, so it is committed for the same reason and
+> changes only when the owning package is renamed or moved. `.claude/hooks/` stays ignored.
+
 **Native consumers are protected by a guard, not by the gate.** A host installing holocron through
 `claude plugin install` auto-discovers `hooks/hooks.json` and does not consult apm's trust gate at
 all. The script therefore exits silently when there is no `apm.lock.yaml` in the working directory,