Fix .gitignore swallowing references/findings-format.md

The findings-*.md rule (for generated timestamped reports) also matched the
findings-format.md reference doc, so it was never tracked. Scope the rule to
digit-prefixed names (findings-[0-9]*) and add the missing reference.

.gitignore

@@ -10,10 +10,12 @@ __pycache__/
 venv/
 env/
 
-# Generated audit reports (timestamped runs are not source)
-findings-*.md
-findings-*.json
-findings-*.txt
+# Generated audit reports (timestamped runs are not source).
+# Scoped to digit-prefixed names so the references/findings-format.md
+# doc is NOT swallowed.
+findings-[0-9]*.md
+findings-[0-9]*.json
+findings-[0-9]*.txt
 
 # Environment / secrets
 .env

repo-hygiene-audit/references/findings-format.md

@@ -0,0 +1,85 @@
+# Findings output format
+
+Three renderers, one finding model. Pick the format for the consumer:
+
+- `text` — terminal triage. Summary line, full `INVENTORY` (every repo, clean
+  ones included), then findings grouped by category.
+- `md` — phase-mapped markdown. Each finding is a `- [ ]` checkbox under the
+  remediation-plan phase heading it belongs to, so a run pastes straight into
+  the project plan as actionable items.
+- `json` — machine-readable for week-over-week diffing and automation.
+
+## Finding model
+
+Every finding is one record:
+
+| Field | Meaning |
+|-------|---------|
+| `domain` | `homelab` / `pbs` / `docker` (the Obsidian vault is out of scope by default — see check-catalog.md) |
+| `repo` | Directory name within the domain |
+| `path` | Absolute path |
+| `category` | `SECURITY` / `AUDITABILITY` / `CLEANUP` / `GIT_STATE` / `DOCS` |
+| `severity` | `high` / `medium` / `low` / `info` |
+| `check` | Stable check id (e.g. `no-git`, `env-world-readable:.env`) |
+| `detail` | Human-readable description of what was found |
+| `hint` | Suggested remediation (informational — the skill does not apply it) |
+| `key` | `domain/repo:check` — stable identifier for dedup/diffing (JSON only) |
+
+The `key` is deliberately stable across runs: a finding that persists keeps the
+same key, so diffing two JSON runs cleanly separates *new drift* (keys that
+appeared) from *remediated items* (keys that disappeared).
+
+## Category → phase mapping
+
+This is how findings line up with the repo-hygiene-remediation plan, so the
+recurring review feeds the same backlog structure the original audit used:
+
+| Category | Plan phase |
+|----------|-----------|
+| `SECURITY` | Phase 2 — Security remediation |
+| `AUDITABILITY` | Phase 3 — Unblock un-auditable repos |
+| `CLEANUP` | Phase 4 — Cross-repo cleanups |
+| `GIT_STATE` | Git state (review before commit/merge) |
+| `DOCS` | Docs (audit follow-up) |
+
+## JSON shape
+
+```json
+{
+  "generated": "2026-05-22T23:05:00",
+  "host": "herbys-dev",
+  "repos_scanned": 39,
+  "summary": {
+    "by_severity": {"high": 11, "medium": 19, "low": 23, "info": 9},
+    "by_category": {"SECURITY": 5, "AUDITABILITY": 9, "CLEANUP": 8,
+                    "GIT_STATE": 27, "DOCS": 13}
+  },
+  "inventory": [
+    {"domain": "docker", "repo": "authelia", "path": "...",
+     "is_git": false, "owner": "root", "git_owner": "", "group": "root",
+     "branch": "", "finding_count": 2}
+  ],
+  "findings": [
+    {"domain": "docker", "repo": "authelia", "path": "...",
+     "category": "AUDITABILITY", "severity": "high", "check": "no-git",
+     "detail": "directory holds real content but has no .git",
+     "hint": "git init + initial commit ...", "key": "docker/authelia:no-git"}
+  ]
+}
+```
+
+## Diffing two runs
+
+```bash
+python scripts/audit.py --format json -o this-week.json
+# ... a week later ...
+python scripts/audit.py --format json -o next-week.json
+
+python3 - <<'PY'
+import json
+a = {f["key"] for f in json.load(open("this-week.json"))["findings"]}
+b = {f["key"] for f in json.load(open("next-week.json"))["findings"]}
+print("NEW drift   :", sorted(b - a))
+print("REMEDIATED  :", sorted(a - b))
+PY
+```