fix: emit state after refreshing runtime info so clients get model updates

The Claude agent model was not showing in the UI ("Model: Unknown") because
refreshRuntimeInfo() updated agent.runtimeInfo but never called emitState()
to notify connected clients of the change.

Fixed by:
1. Adding change detection in refreshRuntimeInfo() to check if model, sessionId,
   or modeId changed
2. Calling emitState(agent) when changes are detected
3. Added debug logging in handleSystemMessage() to confirm model capture

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/server/src/server/agent/agent-manager.ts

@@ -782,7 +782,16 @@ export class AgentManager {
 
   private async refreshRuntimeInfo(agent: ActiveManagedAgent): Promise<void> {
     try {
-      agent.runtimeInfo = await agent.session.getRuntimeInfo();
+      const newInfo = await agent.session.getRuntimeInfo();
+      const changed =
+        newInfo.model !== agent.runtimeInfo?.model ||
+        newInfo.sessionId !== agent.runtimeInfo?.sessionId ||
+        newInfo.modeId !== agent.runtimeInfo?.modeId;
+      agent.runtimeInfo = newInfo;
+      // Emit state if runtimeInfo changed so clients get the updated model
+      if (changed) {
+        this.emitState(agent);
+      }
     } catch {
       // Keep existing runtimeInfo if refresh fails.
     }

packages/server/src/server/agent/providers/claude-agent.ts

@@ -875,6 +875,7 @@ class ClaudeAgentSession implements AgentSession {
     this.persistence = null;
     // Capture actual model from SDK init message (not just the configured model)
     if (message.model) {
+      console.log(`[ClaudeAgentSession] Captured model from SDK init: ${message.model}`);
       this.lastOptionsModel = message.model;
       // Invalidate cached runtime info so it picks up the new model
       this.cachedRuntimeInfo = null;