Copilot CLI: Close Diffs When Client Disconnects

[MRayermannMSFT]

When CLI disconnects from the MCP server, we now close any diffs we had open.

[Copilot]

Pull request overview

This PR updates the Copilot CLI MCP integration so that when a CLI client session disconnects, any diff editors opened on behalf of that session are automatically rejected/closed via the existing diff lifecycle.

Changes:

• Thread sessionId into MCP tool registration and store it on each registered diff (via open_diff).
• Add a disconnect hook in InProcHttpServer and wire it in CopilotCLIContrib to close diffs for the disconnected session.
• Add unit tests for DiffStateManager.closeAllForSession and basic coverage for the new disconnect-listener API.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/extension/agents/copilotcli/vscode-node/tools/openDiff.ts	Adds sessionId to diff registration so diffs can be associated with a CLI session.
src/extension/agents/copilotcli/vscode-node/tools/index.ts	Passes sessionId through when registering MCP tools.
src/extension/agents/copilotcli/vscode-node/test/openDiff.spec.ts	Updates tool registration in tests to provide a sessionId.
src/extension/agents/copilotcli/vscode-node/test/inProcHttpServer.spec.ts	Adds tests for onClientDisconnected listener registration/disposal.
src/extension/agents/copilotcli/vscode-node/test/closeAllForSession.spec.ts	Adds tests for session-scoped diff closure behavior.
src/extension/agents/copilotcli/vscode-node/inProcHttpServer.ts	Adds disconnect listener mechanism and passes sessionId into tool registration.
src/extension/agents/copilotcli/vscode-node/diffState.ts	Adds sessionId to ActiveDiff and implements closeAllForSession.
src/extension/agents/copilotcli/vscode-node/contribution.ts	Registers disconnect handler to close diffs for the disconnected session and updates tool registration callback signature.

Comments suppressed due to low confidence (1)

src/extension/agents/copilotcli/vscode-node/test/inProcHttpServer.spec.ts:68

• The "support multiple listeners" / "only remove the disposed listener" tests currently only assert that listeners haven't been called, but they never trigger a disconnect event, so they don't validate multi-listener behavior. It would be more robust to trigger a simulated disconnect and assert both listeners fire, then dispose one and assert only the remaining one fires on the next disconnect.

	it('should support multiple listeners', () => {
		const listener1 = vi.fn();
		const listener2 = vi.fn();
		server.onClientDisconnected(listener1);
		server.onClientDisconnected(listener2);

		// Both should be registered (we can't easily trigger them without
		// going through the full MCP flow, but at least we verify registration)
		expect(listener1).not.toHaveBeenCalled();
		expect(listener2).not.toHaveBeenCalled();
	});

	it('should only remove the disposed listener', () => {
		const listener1 = vi.fn();
		const listener2 = vi.fn();
		const disposable1 = server.onClientDisconnected(listener1);
		server.onClientDisconnected(listener2);

		disposable1.dispose();

		// listener2 should still be registered
		expect(listener1).not.toHaveBeenCalled();
		expect(listener2).not.toHaveBeenCalled();
	});