feat(doctor): silent-failure check batch — content-hash duplicates, undeclared DB-only pages, heartbeat staleness, db_only collector collision (#2250 #2784 #2787 #2788) (#3457)

Co-Authored-By: Time Attakc <89218912+time-attack@users.noreply.github.com>

docs/integrations/README.md

@@ -69,6 +69,12 @@ health_checks:                  # typed DSL to verify the integration is working
     auth_user: "$TWILIO_ACCOUNT_SID"
     auth_token: "$TWILIO_AUTH_TOKEN"
     label: "Twilio account"
+  - type: heartbeat_max_age     # staleness gate: FAILS `integrations doctor`
+    max_age: 48h                # when the newest heartbeat event is older.
+    label: "Data freshness"     # The other types are point-in-time and stay
+                                # green even when a sense stops producing data.
+output_paths:                   # repo-relative dirs the collector writes files to;
+  - daily/voice/                # lets doctor/sync warn if one lands in db_only
 setup_time: 30 min              # estimated time to complete setup
 ---
 
@@ -86,7 +92,8 @@ a source install, or the global install copy) are trusted. Recipes discovered at
 runtime from `$GBRAIN_RECIPES_DIR` or a cwd-local `./recipes/` are marked untrusted:
 they cannot run `command` health checks, cannot run `http` health checks (SSRF
 defense), and cannot use the deprecated string health_check form. Untrusted recipes
-can still use `env_exists` and `any_of` compositions. To ship a recipe that runs
+can still use `env_exists`, `heartbeat_max_age` (reads only the local heartbeat
+file — no exec, no network), and `any_of` compositions. To ship a recipe that runs
 live checks, contribute it upstream so it becomes package-bundled.
 
 ## The Deterministic Collector Pattern

docs/storage-tiering.md

@@ -51,6 +51,18 @@ When storage configuration is present, `gbrain sync` automatically manages `.git
 - Skipped when the repo is a git submodule (`.git` is a file, not a directory) — submodule .gitignore changes don't survive parent updates. A warning explains.
 - Skipped entirely when `GBRAIN_NO_GITIGNORE=1` is set (escape hatch for shared-repo setups where a maintainer wants gbrain to leave .gitignore alone).
 - Failures (write permission denied, etc.) are caught and logged, never crash sync.
+- Warns when a configured collector's declared output dir (recipe `output_paths`
+  frontmatter) sits inside a `db_only` path: gitignored files never appear in the
+  git-walking sync diff, and `gbrain import` honors `.gitignore` too — the
+  collector would run green while nothing reaches the DB. The
+  `db_only_collector_collision` doctor check surfaces the same trap.
+
+Related doctor coverage: `undeclared_db_only_pages` warns about DB pages with no
+backing file that sit outside every declared `db_only` path. The engine's own
+derive-phase output prefixes (`life/events/`, `atoms/`, `extracts/`,
+`dream-cycle-summaries/`) count as implicitly declared for that check, so healthy
+brains stay quiet without adding them to `gbrain.yml`. They are NOT auto-added to
+`.gitignore` — only explicitly declared `db_only` dirs are.
 
 Example `.gitignore` addition: