GHSA-6xg4-82hv-cp6f

## Summary ACP-only provenance fields in `chat.send` were gated by self-declared client metadata from the WebSocket handshake rather than verified authorization state. ## Impact A normal authenticated operator client could spoof ACP identity labels and inject reserved provenance fields intended only for the ACP bridge. ## Affected Component `src/gateway/server-methods/chat.ts, src/gateway/server/ws-connection/message-handler.ts` ## Fixed Versions - Affected: `<= 2026.3.24` - Patched: `>= 2026.3.28` - Latest stable `2026.3.28` contains the fix. ## Fix Fixed by commit `4b9542716c` (`Gateway: require verified scope for chat provenance`).