registration: self-assigned camera IDs (Option B) + tolerate clockless status

Auto-registration never completed: the firmware announced on the wrong
topic, the hub never replied, and an unregistered node couldn't receive a
reply anyway. Switch to self-assigned IDs:

firmware (esp32-mqtt-bridge.cpp):
- camera_id defaults to the device id (clientID, e.g. rig-86d978)
- always subscribe to <id>/command; announce on the contract topic
  remoterig/cameras/<id>/announce (was the unmatched announce-<id> form)
- drop the bogus numeric timestamp from status (node has no clock)

hub (subscriber.go):
- handleAnnounce registers new cameras under the node's self-assigned id
  (no cam-NNN, no registered reply)
- handleStatus tolerates an empty/invalid timestamp and stamps server-side
  (previously rejected the status outright)

docs/MQTT_CONTRACT.md updated to match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/MQTT_CONTRACT.md

@@ -176,11 +176,19 @@ Published once on ESP32 first boot (or factory reset). Used for auto-registratio
 | `capabilities` | string[] | Supported features |
 | `friendly_name` | string | Default human-readable name |
 
-**Hub behavior on first announce:**
+**Camera IDs (self-assigned — "Option B"):** the node uses a stable
+device-derived id (`rig-<last3 MAC bytes>`, e.g. `rig-86d978`) as its
+`camera_id` from first boot, and uses it for all topics
+(`announce`/`status`/`heartbeat`/`command`). There is no hub-assigned
+`cam-NNN` and no `registered` reply handshake.
+
+**Hub behavior on announce:**
 1. Check if MAC already registered → if yes, update `friendly_name` and log
-2. If new MAC → create camera with auto-generated `camera_id = "cam-<NNN>"` (zero-padded sequential)
+2. If new MAC → insert the camera using the node's self-assigned `camera_id`
-3. Respond by publishing: `remoterig/cameras/<camera_id>/command` with `command: "registered"` payload containing the assigned `camera_id`
+3. Broadcast via SSE that a new camera appeared
-4. Broadcast via SSE that a new camera appeared
+
+> Note: nodes have no real-time clock, so `timestamp` may be absent; the hub
+> stamps received-time server-side.
 
 ### Topic: `remoterig/hub/status`
 

firmware/src/esp32-mqtt-bridge.cpp

@@ -311,23 +311,25 @@ bool connectMQTT() {
 
   Serial.println("[MQTT] Connected");
 
-  // Subscribe to commands (if registered)
+  // Option B: self-assigned, stable camera_id derived from the device id.
-  if (cfg.camera_id.length() > 0) {
+  if (cfg.camera_id.length() == 0) {
-    mqtt.subscribe(mqttTopic("command").c_str(), 2);
+    cfg.camera_id = clientID();   // e.g. "rig-86d978"
   }
 
-  // Announce if new
+  // Subscribe to our command topic.
-  if (cfg.camera_id.length() == 0) {
+  mqtt.subscribe(mqttTopic("command").c_str(), 2);
+
+  // Announce (retained) on the contract topic so the hub registers/tracks us.
+  {
     JsonDocument doc;
     doc["mac_address"]      = WiFi.macAddress();
-    doc["firmware_version"] = "0.3.0-esp32-mqtt-bridge";
+    doc["firmware_version"] = "0.4.0-esp32-mqtt-bridge";
-    doc["friendly_name"]    = "Cam-" + clientID();
+    doc["friendly_name"]    = "Cam-" + cfg.camera_id;
     JsonArray caps = doc["capabilities"].to<JsonArray>();
     caps.add("start_stop"); caps.add("status");
     String payload; serializeJson(doc, payload);
-    String announceTopic = "remoterig/cameras/announce-" + clientID();
+    mqtt.publish(mqttTopic("announce").c_str(), payload.c_str(), true);
-    mqtt.publish(announceTopic.c_str(), payload.c_str(), true);
+    Serial.printf("[MQTT] Announced as %s\n", cfg.camera_id.c_str());
-    Serial.println("[MQTT] Announced for registration");
   }
 
   return true;
@@ -489,7 +491,7 @@ void loop() {
         // Build the MQTT status payload per contract
         JsonDocument mqttDoc;
         mqttDoc["camera_id"]  = cfg.camera_id;
-        mqttDoc["timestamp"]  = millis();
+        // No timestamp: the node has no real clock; the hub stamps on receipt.
         mqttDoc["battery_raw"] = dispBatteryRaw;
         int pct = batteryPct(dispBatteryRaw);
         if (pct >= 0) mqttDoc["battery_pct"] = pct;   // omit when uncalibrated

internal/mqtt/subscriber.go

@@ -151,22 +151,20 @@ func (s *Subscriber) handleStatus(cameraID string, payload []byte) {
 	}
 
 	// Validate required fields
-	if sp.CameraID == "" || sp.Timestamp == "" {
+	if sp.CameraID == "" {
-		log.Printf("MQTT status missing required fields (camera_id, timestamp) from %s", cameraID)
+		log.Printf("MQTT status missing camera_id from %s", cameraID)
 		return
 	}
 
-	// Validate timestamp sanity (reject >5min future, >24h past)
+	// Nodes have no real clock, so tolerate an empty/invalid timestamp by
+	// stamping server-side. Still clamp obviously-bad supplied times below.
+	now := time.Now()
 	ts, err := time.Parse(time.RFC3339, sp.Timestamp)
 	if err != nil {
-		// Try ISO8601 without timezone
+		if ts, err = time.Parse("2006-01-02T15:04:05", sp.Timestamp); err != nil {
-		ts, err = time.Parse("2006-01-02T15:04:05", sp.Timestamp)
+			ts = now
-		if err != nil {
-			log.Printf("MQTT status invalid timestamp %q from %s", sp.Timestamp, cameraID)
-			return
 		}
 	}
-	now := time.Now()
 	if ts.After(now.Add(5 * time.Minute)) {
 		log.Printf("MQTT status timestamp too far in future (%s) from %s — using now", ts, cameraID)
 		ts = now
@@ -374,30 +372,20 @@ func (s *Subscriber) handleAnnounce(cameraID string, payload []byte) {
 		}
 		log.Printf("MQTT announce: camera %s (%s) re-connected", existingID, ap.FriendlyName)
 	} else {
-		// New camera — generate sequential cam-NNN ID
+		// Option B: the node self-assigns its camera_id (the announce topic id).
-		var maxID string
-		s.db.QueryRow("SELECT MAX(camera_id) FROM cameras").Scan(&maxID)
-
-		seq := 1
-		if maxID != "" {
-			fmt.Sscanf(maxID, "cam-%d", &seq)
-			seq++
-		}
-
-		newID := fmt.Sprintf("cam-%03d", seq)
 		_, err = s.db.Exec(`
 			INSERT INTO cameras (camera_id, friendly_name, mac_address, created_at, updated_at)
 			VALUES (?, ?, ?, datetime('now'), datetime('now'))
-		`, newID, ap.FriendlyName, ap.MacAddress)
+		`, cameraID, ap.FriendlyName, ap.MacAddress)
 		if err != nil {
 			log.Printf("MQTT announce insert error for %s: %v", ap.MacAddress, err)
 			return
 		}
 
-		log.Printf("MQTT announce: new camera registered as %s (%s)", newID, ap.FriendlyName)
+		log.Printf("MQTT announce: new camera registered as %s (%s)", cameraID, ap.FriendlyName)
 
 		// Broadcast new camera via SSE
-		cam, err := getCamera(s.db, newID)
+		cam, err := getCamera(s.db, cameraID)
 		if err == nil {
 			s.hub.Broadcast("camera_registered", cam)
 		}