add Langfuse tracing to agent runs and tool calls

api/main.py

@@ -23,6 +23,23 @@ logging.basicConfig(
 )
 
 
+def _get_langfuse():
+    """Lazy Langfuse client — returns None if not configured."""
+    try:
+        from api.config import get_settings
+        s = get_settings()
+        if not s.langfuse_public_key or not s.langfuse_secret_key:
+            return None
+        from langfuse import Langfuse
+        return Langfuse(
+            public_key=s.langfuse_public_key,
+            secret_key=s.langfuse_secret_key,
+            host=s.langfuse_host,
+        )
+    except Exception:
+        return None
+
+
 # ── WebSocket event hub ──
 
 class EventHub:
@@ -136,14 +153,27 @@ async def trigger_fce(req: FCERequest):
         async def on_event(event):
             await event_hub.broadcast({"run_id": run_id, **event})
 
+        langfuse = _get_langfuse()
+        trace = langfuse.trace(
+            name="fce", id=run_id,
+            metadata={"flight_id": req.flight_id, "scenario": scenario_manager.active_id},
+        ) if langfuse else None
+
         try:
             async with connect_servers(["shared", "ops", "passenger"]) as mcp:
-                result = await run_fce(req.flight_id, mcp, on_event=on_event)
+                result = await run_fce(req.flight_id, mcp, on_event=on_event, trace=trace)
             runs[run_id] = {"status": "completed", "agent": "fce", "result": result}
+            if trace:
+                trace.update(output={"status": "completed", "type": result.get("type", "")})
             logger.info("agent_complete agent=fce run_id=%s flight=%s", run_id, req.flight_id)
         except Exception as e:
             runs[run_id] = {"status": "error", "agent": "fce", "error": str(e)}
+            if trace:
+                trace.update(output={"status": "error", "error": str(e)})
             logger.error("agent_error agent=fce run_id=%s error=%s", run_id, e)
+        finally:
+            if langfuse:
+                langfuse.flush()
 
     logger.info("agent_start agent=fce run_id=%s flight=%s", run_id, req.flight_id)
     asyncio.create_task(_run())
@@ -169,14 +199,27 @@ async def trigger_handover(req: HandoverRequest):
         async def on_event(event):
             await event_hub.broadcast({"run_id": run_id, **event})
 
+        langfuse = _get_langfuse()
+        trace = langfuse.trace(
+            name="handover", id=run_id,
+            metadata={"hubs": req.hubs, "scenario": scenario_manager.active_id},
+        ) if langfuse else None
+
         try:
             async with connect_servers(["shared", "ops"]) as mcp:
-                result = await run_handover(hubs=req.hubs, mcp=mcp, on_event=on_event)
+                result = await run_handover(hubs=req.hubs, mcp=mcp, on_event=on_event, trace=trace)
             runs[run_id] = {"status": "completed", "agent": "handover", "result": result}
+            if trace:
+                trace.update(output={"status": "completed"})
             logger.info("agent_complete agent=handover run_id=%s hubs=%s", run_id, req.hubs)
         except Exception as e:
             runs[run_id] = {"status": "error", "agent": "handover", "error": str(e)}
+            if trace:
+                trace.update(output={"status": "error", "error": str(e)})
             logger.error("agent_error agent=handover run_id=%s error=%s", run_id, e)
+        finally:
+            if langfuse:
+                langfuse.flush()
 
     logger.info("agent_start agent=handover run_id=%s hubs=%s", run_id, req.hubs)
     asyncio.create_task(_run())