refactor(agent): add ForEachTool to AgentRegistry for cross-agent tool lookup

Extract the pattern of iterating agents to find a named tool into
AgentRegistry.ForEachTool, simplifying SetMediaStore propagation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/agent/loop.go

@@ -378,17 +378,11 @@ func (al *AgentLoop) SetMediaStore(s media.MediaStore) {
 	al.mediaStore = s
 
 	// Propagate store to send_file tools in all agents.
-	for _, id := range al.registry.ListAgentIDs() {
+	al.registry.ForEachTool("send_file", func(t tools.Tool) {
-		agent, ok := al.registry.GetAgent(id)
+		if sf, ok := t.(*tools.SendFileTool); ok {
-		if !ok {
+			sf.SetMediaStore(s)
-			continue
 		}
-		if tool, ok := agent.Tools.Get("send_file"); ok {
+	})
-			if sf, ok := tool.(*tools.SendFileTool); ok {
-				sf.SetMediaStore(s)
-			}
-		}
-	}
 }
 
 // SetTranscriber injects a voice transcriber for agent-level audio transcription.

pkg/agent/registry.go

@@ -7,6 +7,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/providers"
 	"github.com/sipeed/picoclaw/pkg/routing"
+	"github.com/sipeed/picoclaw/pkg/tools"
 )
 
 // AgentRegistry manages multiple agent instances and routes messages to them.
@@ -100,6 +101,19 @@ func (r *AgentRegistry) CanSpawnSubagent(parentAgentID, targetAgentID string) bo
 	return false
 }
 
+// ForEachTool calls fn for every tool registered under the given name
+// across all agents. This is useful for propagating dependencies (e.g.
+// MediaStore) to tools after registry construction.
+func (r *AgentRegistry) ForEachTool(name string, fn func(tools.Tool)) {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	for _, agent := range r.agents {
+		if t, ok := agent.Tools.Get(name); ok {
+			fn(t)
+		}
+	}
+}
+
 // GetDefaultAgent returns the default agent instance.
 func (r *AgentRegistry) GetDefaultAgent() *AgentInstance {
 	r.mu.RLock()