Token tracking bidi

[alfredjimmy-redbus]

1. Runner.runLive — plugin callbacks for live sessions

File: core/src/main/java/com/google/adk/runner/Runner.java

Problem: Non-live runs already invoked onEventCallback / afterRunCallback; runLive did not. Plugins like RedBusTrackingPlugin and LiveTokenTrackingPlugin never saw live events, so BIDI token usage was never tracked.

Change: In runLiveImpl, for each live event:

• pluginManager.onEventCallback(invocationContext, event) — per event (e.g. each usageMetadata turn)
• pluginManager.afterRunCallback(invocationContext) — once when the live stream completes

Mirrors the existing non-live runImpl path. Session persistence (appendEvent) is unchanged; plugin callbacks are observational only.

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2. GeminiLlmConnection — handle new Live API control messages

File: core/src/main/java/com/google/adk/models/GeminiLlmConnection.java

Problem: google-genai 1.58+ delivers control messages (sessionResumptionUpdate, goAway, voice-activity signals) that ADK did not recognize. They fell through to the “unknown server message” branch, producing error LlmResponses and fake ADK events — observed in RAE as event #123 with hasContent=false right after:

Received unknown or empty server message: {"sessionResumptionUpdate":{...}}

Change: Treat these as no-op control messages (return Optional.empty(), debug log only):

• sessionResumptionUpdate
• goAway
• voiceActivityDetectionSignal
• voiceActivity

Unchanged: Standalone usageMetadata messages still become LlmResponses with usage attached (existing behavior at lines 189–197).

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3. Test coverage

File: core/src/test/java/com/google/adk/models/GeminiLlmConnectionTest.java

• Added convertToServerResponse_withSessionResumptionUpdate_returnsEmpty — confirms resumption updates do not emit error events.

Existing tests still cover:

• Usage-only messages → response with usageMetadata
• Content + usage in same message
• Unknown empty message → error response

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Why this matters for RAE / BIDI voice

Layer | Before | After -- | -- | -- Runner | Live events bypass plugins | RedBusTrackingPlugin.onEventCallback fires per usageMetadata event GeminiLlmConnection | Resumption updates → spurious error events | Control messages ignored; real usage events pass through cleanly

Dependency: Requires google-genai ≥ 1.58.0 (RAE already on 1.58.0).

Downstream (not in ADK): genai-sdk RedBusTrackingPlugin persists per-event usage to rae_tokens; LiveAudioSession logs USAGE_METADATA for confirmation.