feat(gateway): add node capability negotiation foundation

docs/api/PROTOCOL.md

@@ -21,6 +21,7 @@ The gateway provides:
 - **JSON-RPC 2.0**: Structured request/response protocol
 - **Streaming Events**: Real-time updates during agent processing
 - **HTTP Server**: Serves static dashboard and handles webhook endpoints
+- **Node Capability Negotiation**: Optional companion-node role/capability registration
 
 ### Execution Model (Sessions + Per-Session Queue)
 
@@ -563,6 +564,50 @@ When queue policy rejects/supersedes a request before execution, the server emit
 
 Cancel the current agent operation.
 
+### Node Methods
+
+#### `node.register`
+
+Register node role/capabilities for the current WebSocket connection.
+
+**Request:**
+```json
+{
+  "id": 9,
+  "method": "node.register",
+  "params": {
+    "nodeId": "companion-desktop",
+    "role": "companion",
+    "protocolVersion": 1,
+    "capabilities": ["ui.canvas", "notifications"]
+  }
+}
+```
+
+**Response:**
+```json
+{
+  "id": 9,
+  "result": {
+    "registered": true,
+    "node": { "id": "companion-desktop", "role": "companion" },
+    "protocol": { "serverVersion": 1, "clientVersion": 1, "negotiatedVersion": 1 },
+    "capabilities": {
+      "declared": ["ui.canvas", "notifications"],
+      "enabled": ["ui.canvas", "notifications"]
+    }
+  }
+}
+```
+
+#### `node.capabilities.get`
+
+Return negotiated capabilities for the currently registered node connection.
+
+#### `system.capabilities`
+
+Return gateway protocol version, node policy status, and feature-gate snapshot.
+
 **Request:**
 ```json
 {

docs/plans/state.json

@@ -33,10 +33,10 @@
       "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"
     },
     "openclaw-gap-next-steps-3phase": {
-      "status": "in_progress",
+      "status": "completed",
       "date": "2026-02-16",
       "updated": "2026-02-16",
-      "summary": "Defined and began executing a concrete 3-phase implementation plan for remaining high-impact OpenClaw parity work: queue policy parity v2, channel reach expansion (Mattermost first), and companion-node capability negotiation foundation.",
+      "summary": "Completed the 3-phase implementation plan for remaining high-impact OpenClaw parity gaps: queue policy parity v2, Mattermost channel expansion, and companion-node capability negotiation foundation.",
       "file": "2026-02-16-openclaw-gap-next-steps-3phase.md"
     },
     "openclaw-gap-phase1-queue-parity-v2": {
@@ -92,6 +92,33 @@
       ],
       "test_status": "pnpm test:run src/channels/mattermost/adapter.test.ts src/daemon/channels.test.ts src/config/schema.test.ts src/gateway/handlers/services.test.ts src/gateway/handlers/handlers.test.ts + pnpm typecheck + pnpm build passing"
     },
+    "openclaw-gap-phase3-node-capability-foundation": {
+      "status": "completed",
+      "date": "2026-02-16",
+      "updated": "2026-02-16",
+      "summary": "Completed companion-node foundation: protocol payload typing + parsing, node registration/capability handlers (`node.register`, `node.capabilities.get`, `system.capabilities`), connection-level node state tracking, scoped node RPC authorization, node policy config (`server.nodes.*`), docs, and tests.",
+      "files_created": [
+        "src/gateway/handlers/node.ts",
+        "src/gateway/handlers/node.test.ts"
+      ],
+      "files_modified": [
+        "src/gateway/protocol.ts",
+        "src/gateway/protocol.test.ts",
+        "src/gateway/auth.ts",
+        "src/gateway/auth.test.ts",
+        "src/gateway/handlers/index.ts",
+        "src/gateway/router.ts",
+        "src/gateway/server.ts",
+        "src/gateway/server.test.ts",
+        "src/config/schema.ts",
+        "src/config/schema.test.ts",
+        "src/daemon/services.ts",
+        "config/default.yaml",
+        "README.md",
+        "docs/api/PROTOCOL.md"
+      ],
+      "test_status": "pnpm test:run src/gateway/protocol.test.ts src/gateway/auth.test.ts src/gateway/handlers/node.test.ts src/gateway/server.test.ts src/config/schema.test.ts + pnpm typecheck + pnpm build passing"
+    },
     "docs-gateway-auth-config-keys": {
       "status": "completed",
       "date": "2026-02-15",
@@ -3015,12 +3042,12 @@
     "tier2_completion": "4/4 (100%) — inbound webhooks, vector memory search, Dockerfile, heartbeat monitor",
     "tier3_completion": "5/5 (100%) — lane queue, credential redaction, web UI token dashboard, xAI (Grok) provider, Voyage AI embeddings",
     "tier4_completion": "4/4 (100%) — gateway lock, shell completion, Tailscale Serve/Funnel, DM pairing codes",
-    "feature_gap_scorecard": "117/128 match (91%), 0 partial (0%), 11 missing (9%)",
+    "feature_gap_scorecard": "118/128 match (92%), 0 partial (0%), 10 missing (8%)",
     "operator_dx_milestone": "Phase 3 (Live Ops Dashboard): 2/2 plans complete — milestone done",
     "gmail_auth_cli": "flynn gmail-auth command implemented with OAuth2 flow, doctor check, config routed to Telegram",
     "native_audio_support": "completed — smart routing for native audio (Gemini/OpenAI/GitHub) vs Whisper transcription fallback",
     "remaining_phases_completion": "Phase 1: 3/3 (100%) — context levels, command registry, memory structure. Phase 2: 3/3 (100%) — component registry, confidence routing, history index. Phase 3: 2/2 (100%) — adaptive memory/compaction, truthfulness/autonomy hardening",
-    "next_up": "OpenClaw gap phase 3: companion-node capability/version negotiation foundation"
+    "next_up": "OpenClaw gap: Location access (open next scoped implementation checklist)"
   },
   "soul_md_and_cron_create": {
     "date": "2026-02-11",