Add trace logs around chat session opening

[rebornix]

Adds tracing logs to help diagnose chat session opening performance.

Instrumented call path:

• SessionsManagementService.openChat / openSession
• ChatWidgetService.openSession
• ChatViewPane.loadSession
• MainThreadChatSessions._provideChatSessionContent

Each entry logs a start and done total=Xms at trace level so timings can be correlated end-to-end when investigating slow open scenarios.

[github-actions]

Screenshot Changes

Base: d1bbbc1c Current: a3d00608

Changed (1)

agentSessionsViewer/WithMarkdownBadge/Dark

Before	After

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blocks-ci screenshots changed

Replace the contents of test/componentFixtures/blocks-ci-screenshots.md with:

Updated blocks-ci-screenshots.md

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#### editor/codeEditor/CodeEditor/Dark
![screenshot](https://hediet-screenshots.azurewebsites.net/images/cb32a3e854b5734fe5aaca2318f2e0a42ee821b05ea97883ea42c5ba95edb3c3)

#### editor/codeEditor/CodeEditor/Light
![screenshot](https://hediet-screenshots.azurewebsites.net/images/42624fbba5e0db7f32c224b5eb9c5dd3b08245697ae2e7d2a88be0d7c287129b)

#### editor/inlineChatZoneWidget/InlineChatZoneWidget/Dark
![screenshot](https://hediet-screenshots.azurewebsites.net/images/28af1b719f3877d2f048fef10bb4534d5f638c1987bb0536331f4ab50ea0ea7a)

#### editor/inlineChatZoneWidget/InlineChatZoneWidget/Light
![screenshot](https://hediet-screenshots.azurewebsites.net/images/c6c77ca2785665ae66c817cda21a8e5f5ea7d51e798c5b4e5aedcda9fd7323bd)

#### editor/inlineChatZoneWidget/InlineChatZoneWidgetTerminated/Dark
![screenshot](https://hediet-screenshots.azurewebsites.net/images/2fbc12507b59ff950d9612d2df92e6b39d8bf0bf500478e42eca2ead4d1ae206)

#### editor/inlineChatZoneWidget/InlineChatZoneWidgetTerminated/Light
![screenshot](https://hediet-screenshots.azurewebsites.net/images/4632ab04d1fdd7db9ab0e00cce10aefb7a6344eb8869dfce740309a8801cab73)

[Copilot]

Pull request overview

Adds trace-level timing logs to the chat session open pipeline to help diagnose slow session opening across the sessions UI, chat widget/view, and main thread session content provider.

Changes:

• Instrumented session open entry points in SessionsManagementService (openChat, openSession) with start/done total=...ms trace logs.
• Added tracing to ChatWidgetService.openSession to distinguish reveal/view/editor paths and report end-to-end timing.
• Added tracing around ChatViewPane.loadSession and MainThreadChatSessions._provideChatSessionContent to correlate timings across layers.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/browser/widgetHosts/viewPane/chatViewPane.ts	Adds trace timing logs to loadSession including cancellation/error phases.
src/vs/workbench/contrib/chat/browser/widget/chatWidgetService.ts	Adds trace timing logs to openSession and injects ILogService.
src/vs/workbench/api/browser/mainThreadChatSessions.ts	Adds trace timing logs to _provideChatSessionContent.
src/vs/sessions/services/sessions/browser/sessionsManagementService.ts	Switches to trace-level timing logs for openChat/openSession and tweaks warn message format.

Copilot's findings

Comments suppressed due to low confidence (4)

src/vs/workbench/api/browser/mainThreadChatSessions.ts:943

• _provideChatSessionContent logs start and logs done only on the success path. If session.initialize(...) throws (including cancellation), you end up with a start log without a done, which makes timing correlation incomplete. Consider moving the final done total=...ms into a finally block and adding an error=true/cancelled=true marker when appropriate.

This issue also appears on line 898 of the same file.

	private async _provideChatSessionContent(providerHandle: number, sessionResource: URI, token: CancellationToken): Promise<IChatSession> {
		const t0 = Date.now();
		this._logService.trace(`[MainThreadChatSessions] _provideChatSessionContent start handle=${providerHandle} uri=${sessionResource.toString()}`);
		warnOnUntitledSessionResource(sessionResource, this._logService);

		let session = this._activeSessions.get(sessionResource);

		if (!session) {
			session = new ObservableChatSession(
				sessionResource,
				providerHandle,
				this._proxy,
				this._logService,
				this._dialogService
			);
			this._activeSessions.set(sessionResource, session);
			const disposable = session.onWillDispose(() => {
				this._activeSessions.delete(sessionResource);
				this._sessionDisposables.get(sessionResource)?.dispose();
				this._sessionDisposables.delete(sessionResource);
			});
			this._sessionDisposables.set(sessionResource, disposable);
		}

		try {
			const initialSessionOptions = this._chatSessionsService.getSessionOptions(sessionResource);
			await session.initialize(token, {
				initialSessionOptions: initialSessionOptions ? [...initialSessionOptions].map(([optionId, value]) => ({ optionId, value: typeof value === 'string' ? value : value?.id })) : undefined,
			});
			if (session.options) {
				for (const [_, handle] of this._sessionTypeToHandle) {
					if (handle === providerHandle) {
						for (const [optionId, value] of session.options) {
							this._chatSessionsService.setSessionOption(sessionResource, optionId, value);
						}
						break;
					}
				}
			}
			this._logService.trace(`[MainThreadChatSessions] _provideChatSessionContent done total=${Date.now() - t0}ms handle=${providerHandle}`);
			return session;
		} catch (error) {
			session.dispose();
			this._logService.error(`Error providing chat session content for handle ${providerHandle} and resource ${sessionResource.toString()}:`, error);
			throw error;
		}

src/vs/workbench/api/browser/mainThreadChatSessions.ts:901

• These trace logs eagerly call sessionResource.toString() and build template strings even when Trace logging is disabled. Since this method can be called frequently, please guard the trace log construction with canLog(this._logService.getLevel(), LogLevel.Trace) (or similar) so URI stringification and string building only occurs at Trace level.

	private async _provideChatSessionContent(providerHandle: number, sessionResource: URI, token: CancellationToken): Promise<IChatSession> {
		const t0 = Date.now();
		this._logService.trace(`[MainThreadChatSessions] _provideChatSessionContent start handle=${providerHandle} uri=${sessionResource.toString()}`);
		warnOnUntitledSessionResource(sessionResource, this._logService);

src/vs/workbench/contrib/chat/browser/widget/chatWidgetService.ts:112

• These trace logs build template strings and call sessionResource.toString()/Date.now() unconditionally, even when the log level is above Trace. Since this is on the session-opening hot path, please guard the log construction with canLog(logService.getLevel(), LogLevel.Trace) (or a getLevel() === LogLevel.Trace check) so the additional overhead is avoided unless Trace logging is enabled.

		const t0 = Date.now();
		const targetKind = target === ChatViewPaneTarget ? 'view' : (typeof target === 'undefined' ? 'undefined' : 'editor');
		this.logService.trace(`[ChatWidgetService] openSession start uri=${sessionResource.toString()} target=${targetKind}`);

src/vs/sessions/services/sessions/browser/sessionsManagementService.ts:250

• The new openSession tracing only logs done after chatWidgetService.openSession(...) resolves. If that call throws, the start log will have no matching done. For consistent timing correlation, consider emitting the done total=...ms from a finally block with an error=true/cancelled=true attribute as appropriate.

	async openSession(sessionResource: URI, options?: { preserveFocus?: boolean }): Promise<void> {
		const t0 = Date.now();
		const sessionData = this.getSession(sessionResource);
		if (!sessionData) {
			this.logService.warn(`[SessionsManagement] openSession: session not found uri=${sessionResource.toString()}`);
			throw new Error(`Session with resource ${sessionResource.toString()} not found`);
		}
		this.logService.trace(`[SessionsManagement] openSession start uri=${sessionResource.toString()} provider=${sessionData.providerId}`);
		this.isNewChatSessionContext.set(false);
		this._isNewChatInSessionContext.set(false);
		this.setActiveSession(sessionData);

		// Open the active chat (which may have been restored to the last active chat)
		const activeChat = this._activeSession.get()?.activeChat.get();
		const openUri = activeChat?.resource ?? sessionData.resource;
		await this.chatWidgetService.openSession(openUri, ChatViewPaneTarget, { preserveFocus: options?.preserveFocus });
		this.logService.trace(`[SessionsManagement] openSession done total=${Date.now() - t0}ms`);
	}

• Files reviewed: 4/4 changed files
• Comments generated: 4