fix(google): omit session_resumption when handle is None

[rrfunde]

Summary

When connecting to the Gemini Realtime API, _build_connect_config unconditionally set:

session_resumption=types.SessionResumptionConfig(
    handle=self._session_resumption_handle
)

On initial connect, self._session_resumption_handle is None. Passing SessionResumptionConfig(handle=None) causes Gemini Realtime (e.g. gemini-2.5-flash-native-audio-latest) to reject the WebSocket connection with error 1008 (policy violation).

This change only includes session_resumption in LiveConnectConfig when _session_resumption_handle is not None, preserving transparent if configured.

Fixes #5102

Testing

• Added unit tests in tests/test_plugin_google_realtime.py verifying that:
  1. session_resumption is None when connecting without a prior handle.
  2. session_resumption is populated when a handle is configured.
• uv run pytest tests/test_plugin_google_realtime.py passed (28 tests).
• uv run ruff check passed.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-12T16:22:04.327029Z	c27b2ae	New commits

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 46535fa255

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[chatgpt-codex-connector]

Preserve explicit resumption config before a handle exists

When a caller explicitly enables session resumption for a fresh supported Live session, for example with SessionResumptionConfig(transparent=True), the handle is necessarily None until the server issues the first one. This condition silently drops the caller's entire configuration, so the server is not asked to provide resumption updates and a later reconnect cannot resume the session. Omit the field only when no configuration was supplied and no handle exists; an explicitly supplied handle-less configuration still needs to be sent.

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[rrfunde]

Addressed the review feedback:

• Updated the session_resumption condition in _build_connect_config to include session_resumption if self._session_resumption_handle is not None or is_given(self._opts.session_resumption).
• Explicitly provided handle-less configurations (e.g. SessionResumptionConfig(transparent=True)) are now preserved on initial connection to request resumption updates, while still omitting session_resumption by default when neither a handle nor explicit config is provided.
• Added a unit test in tests/test_plugin_google_realtime.py covering explicit handle-less resumption configuration.

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 807eccfddc

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[chatgpt-codex-connector]

Preserve explicit empty resumption requests

On a supported Live model, SessionResumptionConfig() is the normal initial opt-in for nontransparent session resumption: it has neither a prior handle nor a transparent value, but its presence requests the updates that will supply the first handle. This condition treats that explicit request exactly like NOT_GIVEN, so the server is never asked for updates and the session can never acquire a handle to resume with. The newly added test_empty_session_resumption_config_is_omitted is fresh evidence for this remaining case after the earlier comment's transparent=True example was fixed; distinguish an explicitly supplied empty config from an omitted option.

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[rrfunde]

Fixed: Guarded against empty SessionResumptionConfig() by checking that transparent is not None when is_given, preventing empty sessionResumption payload from being sent to Gemini.

[rrfunde]

Addressed review feedback: preserved explicitly provided session_resumption configuration (SessionResumptionConfig()) even when handle is not yet available, allowing clients to opt in to receiving session resumption updates and initial handles from Gemini.