feat: add POST /openclaw endpoint and enrich heartbeats with OpenClaw metadata

- Bridge server now accepts POST /openclaw from OpenClaw plugin
- OpenClawMeta struct stores version, plugin_version, and agents
- Heartbeat sendOnce() enriches payload with plugin metadata when available
- Telemetry Payload adds optional openclaw_version field
- README updated to document /openclaw endpoint and metadata enrichment
- All communication remains optional — Monitor functions without plugin data

internal/bridge/bridge.go

@@ -1,15 +1,19 @@
 // Package bridge provides a local HTTP server on MONITOR_PORT for
 // communication between the HarborForge OpenClaw plugin and Monitor.
 //
-// The plugin queries this endpoint to enrich its telemetry with
-// host/hardware data. The bridge is optional: if monitorPort is 0
-// or not set, the bridge is not started and Monitor operates normally.
+// The bridge serves two purposes:
+//  1. Expose hardware telemetry to the plugin via GET /telemetry
+//  2. Receive OpenClaw metadata from the plugin via POST /openclaw
+//
+// The bridge is optional: if monitorPort is 0 or not set, the bridge
+// is not started and Monitor operates normally.
 package bridge
 
 import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net"
 	"net/http"
@@ -20,6 +24,14 @@ import (
 	"git.hangman-lab.top/zhi/HarborForge.Monitor/internal/telemetry"
 )
 
+// OpenClawMeta holds metadata received from the OpenClaw plugin.
+// This data is optional enrichment for heartbeat uploads.
+type OpenClawMeta struct {
+	Version       string `json:"version"`
+	PluginVersion string `json:"plugin_version"`
+	Agents        []any  `json:"agents,omitempty"`
+}
+
 // Server is the local bridge HTTP server.
 type Server struct {
 	cfg    config.Config
@@ -29,6 +41,9 @@ type Server struct {
 	mu          sync.RWMutex
 	lastPayload *telemetry.Payload
 	lastUpdated time.Time
+
+	openclawMeta    *OpenClawMeta
+	openclawUpdated time.Time
 }
 
 // New creates a bridge server. It does not start listening.
@@ -57,6 +72,14 @@ type bridgeResponse struct {
 	LastUpdated *time.Time         `json:"last_updated,omitempty"`
 }
 
+// GetOpenClawMeta returns the latest OpenClaw metadata received from
+// the plugin, or nil if no metadata has been received.
+func (s *Server) GetOpenClawMeta() *OpenClawMeta {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.openclawMeta
+}
+
 func (s *Server) handler() http.Handler {
 	mux := http.NewServeMux()
 
@@ -91,6 +114,40 @@ func (s *Server) handler() http.Handler {
 		json.NewEncoder(w).Encode(resp)
 	})
 
+	// OpenClaw metadata endpoint — plugin POSTs its metadata here
+	mux.HandleFunc("/openclaw", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+
+		body, err := io.ReadAll(io.LimitReader(r.Body, 64*1024))
+		if err != nil {
+			http.Error(w, "read error", http.StatusBadRequest)
+			return
+		}
+		defer r.Body.Close()
+
+		var meta OpenClawMeta
+		if err := json.Unmarshal(body, &meta); err != nil {
+			http.Error(w, "invalid json", http.StatusBadRequest)
+			return
+		}
+
+		s.mu.Lock()
+		s.openclawMeta = &meta
+		s.openclawUpdated = time.Now()
+		s.mu.Unlock()
+
+		s.logger.Printf("received OpenClaw metadata: version=%s plugin=%s agents=%d",
+			meta.Version, meta.PluginVersion, len(meta.Agents))
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]string{
+			"status": "ok",
+		})
+	})
+
 	return mux
 }