feat(ai): Implement session resumption and context window compression for live api

[hsubox76]

Based on #9624

Moved connection initiation logic from LiveGenerativeModel.connect() into the class so that the LiveSession.resumeSession() method can more easily access it. Since the LiveGenerativeModel.connect() method needs to wait for the connection to be opened successfully, and a constructor can't be async, the class provides a connectionPromise property for external code to tell when the connection has finished opening.

[changeset-bot]

🦋 Changeset detected

Latest commit: bbdcd1c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@firebase/ai	Minor
firebase	Minor

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[github-actions]

Vertex AI Mock Responses Check ⚠️

A newer major version of the mock responses for Vertex AI unit tests is available. update_vertexai_responses.sh should be updated to clone the latest version of the responses: v16.2

[gemini-code-assist]

Code Review

This pull request adds support for session resumption and context window compression in Live sessions. Key changes include the implementation of LiveSession.resumeSession(), the addition of SessionResumptionConfig and ContextWindowCompressionConfig interfaces, and updated server message handling for resumption updates. The review feedback identifies a logic error in the session connection handshake where the wrong setup message was transmitted and private state was incorrectly mutated due to a shallow copy. A leftover debugging log was also identified for removal.

[gemini-code-assist]

The current implementation prepares a local setupMessage variable but then sends this._setupMessage. Furthermore, the mutation at line 107 (setupMessage.setup.sessionResumption = sessionResumption) actually mutates the private this._setupMessage property because the spread at line 105 is only a shallow copy. It is better to avoid mutating the stored setup message and ensure the correctly prepared object is sent to the handler.

Suggested change

	const setupMessage = { ...this._setupMessage };
	if (sessionResumption) {
	setupMessage.setup.sessionResumption = sessionResumption;
	}
	this._webSocketHandler.send(JSON.stringify(this._setupMessage));
	const setupMessage: _LiveClientSetup = {
	...this._setupMessage,
	setup: {
	...this._setupMessage.setup,
	...(sessionResumption ? { sessionResumption } : {})
	}
	};
	this._webSocketHandler.send(JSON.stringify(setupMessage));

[gemini-code-assist]

Remove the console.log statement used for debugging.

Suggested change

	await this.close();
	console.log('closed');
	await this._connectSession(sessionResumption);
	await this.close();
	await this._connectSession(sessionResumption);