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 ## [Unreleased]
 
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 ### ✨ New Features
 
 - **Antigravity AI Credits Fallback:** Automatically retries with `GOOGLE_ONE_AI` credit injection when free-tier quota is exhausted. Per-account credit balance (5-hour TTL) is cached from SSE `remainingCredits` and exposed as a numeric badge in the Provider Usage dashboard (#1190 — thanks @sFaxsy)
-- **Claude Code Native Parity:** Full header/body signing parity with the Claude Code 2.1.87 OAuth client — CCH xxHash64 body signing, dynamic per-request fingerprint, bidirectional TitleCase ↔ lowercase tool name remapping (14 tools), API constraint enforcement (`temperature=1` for thinking, max 4 `cache_control` blocks, auto-inject ephemeral on last user message), and optional ZWJ obfuscation (#1188 — thanks @RaviTharuma)
+- **Claude Code Native Parity:** Full header/body signing parity with the Claude Code 2.1.87 OAuth client — CCH xxHash64 body signing, dynamic per-request fingerprint, bidirectional TitleCase ↔ lowercase tool name remapping (14 tools), API constraint enforcement (`temperature=1` for thinking, max 4 `cache_control` blocks, auto-inject ephemeral on last user message), and optional ZWJ obfuscation. Wired into `BaseExecutor` for automatic CCH signing on all `anthropic-compatible-cc-*` providers and into `chatCore` for synchronous parity pipeline steps (#1188 — thanks @RaviTharuma)
 - **Per-Connection Codex Defaults:** Codex Fast Service Tier and Reasoning Effort settings are now per-connection instead of a single global toggle. Existing connections are migrated automatically on startup via an idempotent backfill migration (#1176 — thanks @rdself)
+- **xxhash-wasm dependency:** Added `xxhash-wasm@^1.1.0` for CCH signing (xxHash64 with seed `0x6E52736AC806831E`)
 
 ### 🐛 Bug Fixes
 
 - **Search Cache Coalescing with TTL=0:** Fixed a bug where providers configured with `cacheTTLMs: 0` (caching explicitly disabled) still had concurrent requests coalesced and returned `{ cached: true }`. Now each call gets its own independent upstream fetch (#1178 — thanks @sjhddh)
+- **Antigravity Credit Cache Alignment (PR #1190):** Reconciled `accountId` derivation between `AntigravityExecutor.collectStreamToResponse` and `getAntigravityUsage` to use consistent cache keys (`email || sub || "unknown"`). Previously, SSE-parsed credit balances could be written under a different key than the one read by the usage dashboard, causing stale/missing credit badges
+- **CC-compatible test assertion:** Fixed pre-existing test that expected no `cache_control` on system blocks — the billing header system block now carries `cache_control: { type: "ephemeral" }` per PR #1188 design
 - **Codex Combo Smoke Test False Positives:** Fixed combo tests incorrectly reporting `ERROR` for valid Codex streaming responses when `response.output` is empty but text deltas were emitted. The summary now falls back to accumulated delta text (#1176 — thanks @rdself)
 - **Electron NODE_PATH Resolution (Windows):** Fixed Electron desktop startup failures on Windows packaged builds caused by native modules (`better-sqlite3`) being under `app.asar.unpacked` while helpers were in `app/node_modules`. `resolveServerNodePath()` now merges both locations with deduplication and existence checks (#1172 — thanks @backryun)
 
 ### ⚠️ Breaking Changes
 
 - **`DELETE /api/settings/codex-service-tier` removed:** This endpoint no longer exists. Codex Service Tier configuration has moved to per-connection `providerSpecificData.requestDefaults`. Existing connections are migrated automatically on first startup after upgrade. Any external scripts or integrations that call this endpoint should be updated — use `PUT /api/providers/:id` with `providerSpecificData.requestDefaults.serviceTier` instead (#1176).
+- **CCH signing on CC-compatible providers:** All requests to `anthropic-compatible-cc-*` providers now include an xxHash64 integrity token (`cch=...`) in the billing header. Providers that do not validate CCH will ignore it (no behavioral change), but any custom middleware inspecting the billing header should expect a 5-character hex token instead of the `00000` placeholder
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 ## [3.6.4] — 2026-04-12