ErrorFrames propagating upstream from downstream processors (e.g. TTS) would
enter the ServiceSwitcher via process_frame, traverse the active service sub-pipeline,
and reach push_frame where they incorrectly triggered failover. Now only errors whose
processor is one of the managed services trigger handle_error. Also fix the log in
handle_error to attribute errors to the actual source processor rather than the
current active_service.
Closes#4139
* Add ServiceSwitcherStrategyFailover for automatic error-based service switching
Introduce a strategy hierarchy: ServiceSwitcherStrategy (base) →
ServiceSwitcherStrategyManual (handles ManuallySwitchServiceFrame) →
ServiceSwitcherStrategyFailover (adds error-based failover). ServiceSwitcher
now defaults to ServiceSwitcherStrategyManual with strategy_type optional.
Non-fatal ErrorFrames are forwarded to the strategy via handle_error().
* Move metadata request into _set_active_if_available
Requesting metadata is part of making a service active, so it belongs
alongside setting _active_service and firing on_service_switched. This
removes the duplicate queue_frame calls from ServiceSwitcher push_frame
and process_frame.
Add a `service` field so the frame targets a specific service, allowing
ServiceSwitcher.push_frame to consume it only when the targeted service
matches the active service. STTService and test mocks now push the frame
downstream after handling instead of silently consuming it.
- Make ServiceSwitcherStrategy inherit from BaseObject with properties
for services and active_service, and move initial service selection
into the base class
- Add on_service_switched event to ServiceSwitcherStrategy
- handle_frame now returns the switched-to service (or None), allowing
ServiceSwitcher to swallow ManuallySwitchServiceFrame on switch and
request metadata from the new active service
- Override push_frame to suppress RequestMetadataFrame and
ServiceMetadataFrame from inactive services
- Remove ServiceSwitcherFilter and ServiceSwitcherFilterFrame in favor
of plain FunctionFilter instances with closures that check the
strategy's active service directly
- FunctionFilter: add FilterType alias
- FunctionFilter: when direction is None, frames in both directions
are filtered instead of just one
- Add docstrings to ServiceSwitcher and its components
Refactor TranscriptionUserTurnStopStrategy and TurnAnalyzerUserTurnStopStrategy
to use VADUserStoppedSpeakingFrame as the ground truth for when speech ended,
rather than triggering timeouts from transcription frames.
Immediate is the "default", i.e. has the more obvious name (e.g. `ManuallySwitchServiceFrame` v `ManuallySwitchServiceControlFrame`), since that's *probably* what users will want to reach for. Also, the immediate frames are more likely to behave like what we had before the last few commits, where the service switch would always "jump the queue" by having an immediate effect once it hit the `ServiceSwitcher` in the pipeline, jumping ahead of frames in front of it destined for the service.
