Fix chat perf to addRequest first

[pwang347]

No description provided.

[Copilot]

Pull request overview

This PR restructures chat request sending to improve perceived performance by creating the request model (and triggering UI update) before doing potentially slow async work like hook/instruction collection.

Changes:

• Refactors ChatServiceImpl to call model.addRequest(...) before awaiting hook/instruction collection, and collects hooks + instructions in parallel afterward.
• Moves automatic-instruction collection (previously done in the widget) into the service behind a new instructionContext option.
• Updates ChatWidget to pass instructionContext and removes its prior _autoAttachInstructions flow.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/common/chatService/chatServiceImpl.ts	Creates request model earlier; adds async hook/instruction collection helpers; integrates collected instructions into variableData before invoking the agent.
src/vs/workbench/contrib/chat/common/chatService/chatService.ts	Adds instructionContext to IChatSendRequestOptions (and imports ChatModeKind).
src/vs/workbench/contrib/chat/browser/widget/chatWidget.ts	Removes widget-side auto instruction attachment and passes instructionContext into sendRequest.

Copilot's findings

Comments suppressed due to low confidence (2)

src/vs/workbench/contrib/chat/common/chatService/chatService.ts:1432

• instructionContext is required for instruction collection in ChatServiceImpl, but pending/queued requests are persisted with a serialized sendOptions that currently does not include this field (see serializeSendOptions/ISerializableSendOptions in chatModel.ts). After reload/restore, queued requests may run without automatic instruction collection. Consider adding instructionContext (or enough data to recompute it) to the serializable send-options schema so restored pending requests behave the same as live ones.

	instructionContext?: {
		modeKind: ChatModeKind;
		enabledTools?: UserSelectedTools;
		enabledSubAgents?: readonly string[];
	};

src/vs/workbench/contrib/chat/common/chatService/chatServiceImpl.ts:1165

• collectInstructions logs an error for any thrown exception, including request cancellation. Since this uses the request cancellation token, cancellations will likely produce noisy error logs. Consider checking isCancellationError(err) (or token.isCancellationRequested) and skipping logging (or lowering to trace) for cancellations.

				} catch (err) {
					this.logService.error('[ChatService] Failed to collect instructions:', err);
					return [];

• Files reviewed: 3/3 changed files
• Comments generated: 3