v3.10.9: Antigravity context normalizer, Claude thinking fix, endpoint lockdown, cobra91 PR #4

Antigravity-only changes (no other providers touched):
- Production-only endpoints (cloudcode-pa.googleapis.com), sandbox blocked
- AntigravityContextNormalizer: bounded context for every request
- Simple message detector: 'hi' sends minimal payload
- Auto-reset polluted context (200+ items with simple msg)
- Claude thinking: maxOutputTokens=64000, snake_case config, VALIDATED toolConfig
- Claude budgets: low=8192, medium=16384, high=32768

z.ai/OpenRouter (cobra91 PR #4):
- Full OpenClaw attribution headers for z.ai
- X-OpenRouter-Cache header for OpenRouter

Other fixes:
- Linux Re-OAuth: load_oauth_secrets() undefined, now inline
- GLib.idle_add lambda truthy tuple fix
- Project discovery uses production endpoint

CHANGELOG.md

@@ -1,5 +1,26 @@
 # Changelog
 
+## v3.10.9 (2026-05-25)
+
+**Antigravity Overhaul — Context Normalizer, Claude Thinking Fix, Endpoint Lockdown**
+
+### Antigravity Endpoint Lockdown
+- Production-only: `cloudcode-pa.googleapis.com` by default
+- Sandbox/staging blocked unless `ALLOW_ANTIGRAVITY_STAGING=1`
+- 403 SERVICE_DISABLED falls through, 429 returns to client
+
+### AntigravityContextNormalizer
+- Bounded context — no more 136-item polluted requests for "hi"
+- Simple message detector, auto-reset polluted context
+- Duplicate removal, tool output budget, hard char limits
+
+### Claude Thinking Fix (Antigravity-only)
+- Fixed 400 error: `maxOutputTokens=64000` when thinking enabled
+- Snake_case config, VALIDATED toolConfig, proper budgets
+
+### z.ai / OpenRouter (cobra91 PR #4)
+- Full OpenClaw attribution headers, OpenRouter caching
+
 ## v3.10.8 (2026-05-25)
 
 **OAuth & Antigravity Endpoint Fixes**