fix(daily): queue outbound messages until transport joins

[omChauhanDev]

Please describe the changes in your PR. If it is addressing an issue, please reference that as well.

Fixes #3578

Problem

A race condition exists during pipeline startup when using RTVIObserver with DailyTransport. The observer emits messages (e.g., bot-ready, metrics) immediately upon receiving the StartFrame, but DailyTransport.join() is asynchronous. This causes the transport to reject messages with ERROR | Unable to send message: Unable to send messages before joining.

Solution

Buffer outbound messages in _join_message_queue and flush them once join succeeds.

Testing

Before :

After :

Also verified(at client side) that initial messages are now successfully received after the transport joins.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/pipecat/transports/daily/transport.py	0.00%	8 Missing ⚠️

Files with missing lines	Coverage Δ
src/pipecat/transports/daily/transport.py	0.00% <0.00%> (ø)

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[aconchillo]

I don't think we need an additional task. We can just queue the messages and flush them in join() when we know we are joined.

Also, maybe rename _message_queue to _join_message_queue so it's a bit more clear what it is.

[aconchillo]

I'd just add a small function self._flush_join_messages().

[omChauhanDev]

yes, this sounds much cleaner....done thanks