feat(dashboard): add model tier default controls and document cancel path

docs/api/PROTOCOL.md

@@ -698,6 +698,9 @@ When queue policy rejects/supersedes a request before execution, the server emit
 
 Cancel the current agent operation.
 
+Used by the web dashboard/chat stop button and channel-level `/stop` / `/cancel` command fast-paths.
+Cancellation is best-effort and stops at the next agent/tool-loop safe point.
+
 ### Node Methods
 
 #### `node.register`

docs/plans/state.json

@@ -5807,5 +5807,29 @@
       "src/backends/native/agent.ts"
     ],
     "test_status": "4/4 passing"
+  },
+  "dashboard-model-defaults-and-stop-controls": {
+    "date": "2026-02-19",
+    "summary": "Added dashboard controls for persistent model tier defaults (`agents.primary_tier`, `agents.delegation.*`) and background provider/model overrides with fallback tier (`agents.background_models.*`). Added command-registry `/stop` (alias `/cancel`), wired channel/gateway cancellation services, implemented web chat send-button stop state + `agent.cancel` wiring, and added Telegram `/stop` + `/cancel` command forwarding.",
+    "files_modified": [
+      "src/config/schema.ts",
+      "src/gateway/handlers/config.ts",
+      "src/backends/native/orchestrator.ts",
+      "src/context/compaction.ts",
+      "src/daemon/routing.ts",
+      "src/gateway/session-bridge.ts",
+      "src/commands/types.ts",
+      "src/commands/builtin/index.ts",
+      "src/commands/index.ts",
+      "src/gateway/handlers/agent.ts",
+      "src/gateway/ui/pages/chat.js",
+      "src/gateway/ui/pages/dashboard.js",
+      "src/channels/telegram/adapter.ts",
+      "src/channels/telegram/adapter.test.ts",
+      "src/commands/builtin/index.test.ts",
+      "src/gateway/handlers/agent.test.ts",
+      "docs/api/PROTOCOL.md"
+    ],
+    "test_status": "pnpm test:run src/commands/builtin/index.test.ts src/channels/telegram/adapter.test.ts src/gateway/handlers/agent.test.ts src/gateway/session-bridge.test.ts src/daemon/routing.test.ts src/config/schema.test.ts src/gateway/handlers/handlers.test.ts + pnpm typecheck passing"
   }
 }