fix(rtc): drop late SFU subscriber offers when peer connection is closed

[aliev]

Why

_on_subscriber_offer unconditionally calls setRemoteDescription on subscriber_pc. If an offer arrives after the connection has been torn down (slow asyncio loop under load, SFU sending a late renegotiation), aiortc raises InvalidStateError: Cannot handle offer in signaling state "closed". The exception then propagates through the pyee error path and kills the surrounding session.

Reproduces reliably under load: when several concurrent agent sessions run on one pod and the asyncio loop falls behind, session cleanup and a late SFU offer race. We've been observing this pattern on a production deploy that runs multiple agent sessions per pod — each unhandled error visibly drops sessions for users mid-call.

Changes

• In _on_subscriber_offer, guard against a missing or closed subscriber_pc: drop the offer and log at debug level. Nothing to negotiate with a closed connection.

Summary by CodeRabbit

• Bug Fixes
  • Improved video connection stability by ignoring late or invalid subscriber offers when a session is no longer active.
  • Such offers are now safely dropped and logged at debug level, preventing unnecessary negotiation attempts and avoiding unexpected connection errors or terminations.
  • Reduces spurious error propagation for closed or missing subscriber sessions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b71a7676-6c81-466c-ace1-04f9f3509d72

📥 Commits

Reviewing files that changed from the base of the PR and between e19c479 and b1442bf.

📒 Files selected for processing (1)

• getstream/video/rtc/connection_manager.py

🚧 Files skipped from review as they are similar to previous changes (1)

• getstream/video/rtc/connection_manager.py

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📝 Walkthrough

Walkthrough

A single defensive guard is added to ConnectionManager._on_subscriber_offer that detects and drops subscriber SDP offers when the peer connection is unavailable or already closed, preventing InvalidStateError from propagating through the session.

Changes

Subscriber SDP Offer Late-Arrival Guard

Layer / File(s)	Summary
Offer Reception Guard getstream/video/rtc/connection_manager.py	After acquiring the subscriber negotiation lock, an early-return check drops offers if subscriber_pc is None or signalingState == "closed". A debug log message records the dropped offer.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

A rabbit hops through late-arriving streams,
Checks if the connection still dreams—
If closed it be, the offer falls,
Silent logs where echo stalls,
The session sleeps and error calms. 🐰✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: adding a guard to drop late SFU subscriber offers when the peer connection is closed, which directly matches the code change and PR objectives.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/drop-late-subscriber-offer

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