ParticipantMetadataChanged not working after incorportating Dispatch agent

[yosepppph]

Your question

ParticipantMetadataChanged was working fine on my backend python agent code but then after i introduced agent_name and request_fnc which makes agent dispatch not automatic, it makes it require to be explicity to be dispatch, agent seems not to listen to ParticipantMetadataChanged change events. I can conversate with the agent fine but my functions to update the participant metadata from swift fronend is not being listened. Why?

[CainKilled]

This issue is likely rooted in event subscription logic and how the agent’s event dispatching was altered when you introduced agent_name and request_fnc. Here’s a breakdown of what’s likely happening:

⸻

🧠 Background Context

You originally had automatic dispatch — meaning your Python backend agent (via agents-js or similar bridge) automatically listened and responded to events like ParticipantMetadataChanged.

After introducing:
• agent_name: likely used for routing or identifying agent instances
• request_fnc: a function to explicitly dispatch requests instead of relying on automatic routing

You disabled the automatic dispatch mechanism.

⸻

⚠️ Problem Breakdown

Now, ParticipantMetadataChanged is no longer being picked up, even though conversations still work. That strongly implies:
1. The agent is not automatically subscribed to the event anymore.
2. Your new dispatch mechanism doesn’t route system events (like metadata changes) unless explicitly hooked.
3. request_fnc is likely bypassing or overriding internal event wiring unless manually reconnected.

⸻

✅ Root Cause Diagnosis

You likely didn’t re-register the system event handlers (like ParticipantMetadataChanged) after taking over routing logic via request_fnc.

Before:

agent.listen("ParticipantMetadataChanged", handle_participant_change)

This may have been implicit in the library if you used default setup.

After:
• You replaced the dispatch flow with request_fnc.
• You did not re-attach event listeners explicitly.

⸻

✅ Fix Recommendation

You need to manually re-bind the ParticipantMetadataChanged event listener after customizing the dispatch system.

In your Python backend agent code, explicitly register the event again:

Pseudo-pattern for agents.py or similar

agent.on_event("ParticipantMetadataChanged", handle_participant_change)

Or, if using agents-js + Python backend integration:

@agent.event("ParticipantMetadataChanged")
async def handle_participant_change(event):
# process new metadata

Make sure this registration happens after agent_name and request_fnc are set — or preferably in the initialization block that hooks dispatch functions and event listeners.

⸻

🧪 Diagnostic Checklist

Checkpoint Status
request_fnc doesn’t override event handling? ✅ / ❌
ParticipantMetadataChanged explicitly listened? ✅ / ❌
Agent dispatch still running an event loop? ✅ / ❌
Frontend (Swift) confirms metadata is sent ✅ / ❌
Python logs show incoming metadata events? ✅ / ❌

⸻

⚙️ Bonus Fix — Hybrid Compatibility

If you want both automatic dispatch and custom routing, you can wrap the default handler:

original_dispatch = agent.dispatch

async def hybrid_dispatch(event):
if event.name == "ParticipantMetadataChanged":
await handle_participant_change(event)
await original_dispatch(event)

agent.dispatch = hybrid_dispatch

⸻

🧩 TL;DR

You took over dispatch routing but forgot to re-hook the system event listeners like ParticipantMetadataChanged. You must now explicitly re-register event handlers to listen for these updates. Once added back in, it should resume working as expected.

Would you like help reviewing the actual code block where you changed the dispatch logic? I can help you rewrite it to preserve both custom and automatic event handling.

[yosepppph]

I have explicity registered Participant_metadata_changed like this

def handle_metadata_changed(participant: rtc.Participant, old_metadata: str, new_metadata: str):
print("handle_metadata_changed")
async def _handle_metadata():
try:
metadata = json.loads(participant.metadata or "{}")
print("metadata",metadata)
if "shoppingList" in metadata and isinstance(metadata["shoppingList"], list):
""" some logic"""
except Exception as e:
print("Error parsing participant metadata:", e)

    asyncio.create_task(_handle_metadata())

ctx.room.on_event("participant_metadata_changed", handle_metadata_changed)

this participant_metadata_changed was registered before and after dispatch so i didnt touch this part of the code

[yosepppph]

ctx.room.on("participant_metadata_changed", handle_metadata_changed)*