docs: felhom.eu REPORT (HostLeafChecker) + hub README + self-health arc complete (spike doc)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pg8ANF97SEeKYSN5Jxw3qJ

documentation/audits/SPIKE-controller-agent-channel-health-2026-06-29.md

@@ -111,6 +111,22 @@ logged `transient down (unreachable, 1/2) — suppressed` then `agent channel DO
 `allowedEventTypes` allowlist rejected the controller-pushed `agent_channel_*` events (HTTP 400) —
 fixed in **hub v0.20.0**. See `felhom-controller/REPORT.md` + CHANGELOG v0.90.0.
 
+## Self-health arc COMPLETE (2026-06-29)
+
+This channel-check is one of three independent angles on the original silent-multi-day-outage incident
+class, all now shipped + live-validated:
+1. **agent** watches its own privileged capabilities (v0.44.0 + the build-time sudoers gate).
+2. **controller** watches its link to the agent — this channel-health check (v0.90.0) + F2 born-down
+   alerting (v0.91.0).
+3. **hub** proactively watches every agent's served local-API **leaf fingerprint** fleet-wide
+   (agent v0.48.0 reports it; hub v0.22.x `HostLeafChecker` → `host_leaf_changed`), independent of any
+   controller. Live: a leaf regen raised `host_leaf_changed` (`82078fab…→60b5974d…`) AND the controller
+   `agent_channel_pin_mismatch` — complementary detection.
+
+Prevention also shipped: agent v0.46.0 loud-WARNs a regenerated leaf + `felhom-host-install.sh`
+`--preserve-state-from`/populated-host guard. The original incident is now both prevented and caught
+from three angles. (Remaining future enhancement: the served-fp-vs-pinned-fp authoritative cross-check.)
+
 ## Teardown — confirmed
 
 Throwaway `channelspike_test.go` removed (build-server working tree clean — `git status` shows it