docs: handoff + decisions — Google Home TV integration live end-to-end

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

DECISIONS.md

@@ -37,6 +37,16 @@ Format: `YYYY-MM-DD: <decision> — <why>`
   immediate OFF-after-ON can fail. Retry covers it; normal case (TV already up)
   succeeds first try in ~3s. Bounded under the bridge's 60s subprocess timeout.
 
+- **2026-06-06: Google Home via the free manual `google_assistant` integration**
+  (not Nabu Casa). Exposed only `switch.big_tv_lg_tv`. Linked end-to-end and verified.
+  Three non-obvious requirements that were each a separate failure mode:
+  account-linking **Scopes must include `email` + `name`** (blank → no login page);
+  the **"HTTP basic auth header" checkbox must be OFF** (HA OAuth is secretless →
+  checked = `/auth/token` 401); and the Google **Test must be activated by the same
+  account used in the Home app** (slingshooter08). The GCP OAuth consent screen is
+  *not* part of smart-home linking — don't touch it (shared project runs WP Mail SMTP).
+  Full detail + security-cleanup list in `.claude/handoffs/2026-06-06-*.md`.
+
 ## Deferred / Rejected
 - **DHCP reservation for the TV (static IP):** not done — Pi-hole doesn't run
   DHCP (router does), so it's Seth's action on the router. The cached-IP probe