feat(gateway): support per-channel and per-session queue policy overrides

docs/plans/state.json

@@ -17,7 +17,7 @@
       "status": "completed",
       "date": "2026-02-16",
       "updated": "2026-02-16",
-      "summary": "Added configurable gateway lane queue policy (`server.queue`) with mode (`collect|steer|interrupt`), per-lane cap, and overflow behavior (`drop_old|drop_new`). Wired through daemon -> gateway runtime, expanded LaneQueue behavior/tests, and documented the new config in README + default config.",
+      "summary": "Added configurable gateway lane queue policy (`server.queue`) with mode (`collect|steer|interrupt`), per-lane cap, overflow behavior (`drop_old|drop_new`), and per-channel/per-session overrides. Wired through daemon -> gateway runtime, applied override resolution in `agent.send`, expanded queue + handler tests, and documented config usage in README + default config.",
       "files_modified": [
         "src/gateway/lane-queue.ts",
         "src/gateway/lane-queue.test.ts",
@@ -26,9 +26,11 @@
         "src/config/schema.ts",
         "src/config/schema.test.ts",
         "config/default.yaml",
-        "README.md"
+        "README.md",
+        "src/gateway/handlers/agent.ts",
+        "src/gateway/handlers/agent.test.ts"
       ],
-      "test_status": "pnpm test:run src/gateway/lane-queue.test.ts src/config/schema.test.ts + pnpm typecheck passing"
+      "test_status": "pnpm test:run src/gateway/lane-queue.test.ts src/gateway/handlers/agent.test.ts src/config/schema.test.ts + pnpm typecheck passing"
     },
     "docs-gateway-auth-config-keys": {
       "status": "completed",