audit(channel-health): IMPLEMENTED — controller v0.90.0 + hub v0.20.0 allowlist; live-validated

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

@@ -100,6 +100,17 @@ No wrinkle blocks a straightforward slice. The single thing to get right: **clas
 error (latching, config) distinctly from runtime errors (mostly transient)**, and **probe via the
 memoized client** so the check can't lie. Debounce transient reasons (N≥2) to avoid restart-blip noise.
 
+## IMPLEMENTED 2026-06-29 — controller v0.90.0 (+ hub v0.20.0)
+
+The channel-check slice shipped per this spike's GO: `internal/channelhealth` (a ~60s scheduler job
+probing via the memoized `Server.ProbeAgentChannel`, the Q1 classifier, N≥2 debounce for transient
+reasons, first-obs seed) + an English operator-only Notifier event + a Hungarian dashboard banner.
+Live-validated on guest 9201: a clean agent restart fired **no** alert (debounce); a sustained stop
+logged `transient down (unreachable, 1/2) — suppressed` then `agent channel DOWN (up→down:unreachable)`
++ the dashboard banner; start → `recovered`. One thing the spike didn't predict: the hub's
+`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.
+
 ## Teardown — confirmed
 
 Throwaway `channelspike_test.go` removed (build-server working tree clean — `git status` shows it