WebSocket request/response headers

[chrmarti]

Cherry-picking #4160

[Copilot]

Pull request overview

This PR cherry-picks changes from PR #4160 to add WebSocket request/response header support. It enables WebSocket connections to send full authentication and intent headers (matching the HTTP path), captures response headers from the HTTP upgrade handshake, and propagates request IDs to telemetry events.

Changes:

• Introduces HeadersImpl (a reusable IHeaders implementation), WebSocketConnection, and WebSocketConnectOptions types; adds createWebSocket to the IFetcherService interface
• Replaces the ad-hoc secret key parameter in WebSocket connection creation with a flexible headers map, and captures server response headers via a monkey-patched undici agent
• Extends all WebSocket telemetry events with requestId and gitHubRequestId fields from the handshake response headers

Reviewed changes

Copilot reviewed 14 out of 16 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/platform/networking/common/fetcherService.ts	Adds HeadersImpl, WebSocketConnection, WebSocketConnectOptions and createWebSocket to IFetcherService
src/platform/networking/vscode-node/fetcherServiceImpl.ts	Implements createWebSocket using undici to intercept HTTP 101 response headers
src/platform/networking/node/chatWebSocketManager.ts	Refactors connection creation to use headers map; exposes responseHeaders on connections
src/platform/networking/node/chatWebSocketTelemetry.ts	Adds requestId/gitHubRequestId to all WebSocket telemetry events
src/platform/networking/node/nodeFetcher.ts	Replaces inline anonymous IHeaders implementation with new HeadersImpl
src/platform/networking/node/test/nodeFetcherService.ts	Adds stub createWebSocket to implement updated interface
src/extension/prompt/node/chatMLFetcher.ts	Builds and passes full header set to WebSocket connection; reads response x-request-id
src/lib/node/chatLibMain.ts	Stub createWebSocket in SingleFetcherService
src/platform/networking/test/node/networking.spec.ts	Stub createWebSocket in test fetcher
src/platform/endpoint/node/test/routerDecisionFetcher.spec.ts	Stub createWebSocket in test fetcher
src/platform/authentication/test/node/copilotToken.spec.ts	Stub createWebSocket in test fetcher
src/extension/mcp/test/vscode-node/util.ts	Stub createWebSocket in fixture fetcher
package.json / package-lock.json / chat-lib/package.json / chat-lib/package-lock.json	Bumps @vscode/copilot-api from 0.2.13 to 0.2.15

Files not reviewed (1)

• chat-lib/package-lock.json: Language not supported

Comments suppressed due to low confidence (1)

src/platform/networking/node/chatWebSocketManager.ts:304

• In the onClose handler during the connection setup phase (the close-before-open scenario), this._responseHeaders is not updated from connection.responseHeaders before calling the telemetry sender. By contrast, the onError handler does update this._responseHeaders = connection.responseHeaders before accessing this._requestId and this._gitHubRequestId. If the server sends response headers before closing (e.g., in an HTTP 401/403 upgrade rejection), those headers won't be available in the closeDuringSetup telemetry. The fix is to add this._responseHeaders = connection.responseHeaders; at the beginning of the onClose handler in the setup phase, just like it's done in onError.

			const onClose = (event: CloseEvent) => {
				cleanup();
				this._state = ConnectionState.Closed;
				const connectDurationMs = Date.now() - (this._connectStartTime ?? Date.now());
				const closeCodeDescription = wsCloseCodeToString(event.code);
				this._logService.debug(`[ChatWebSocketManager] Connection closed during setup for conversation ${this._conversationId} turn ${this._turnId} (code: ${event.code} ${closeCodeDescription}, reason: ${event.reason || '<empty>'}, wasClean: ${event.wasClean})`);
				ChatWebSocketTelemetrySender.sendCloseDuringSetupTelemetry(this._telemetryService, {
					conversationId: this._conversationId,
					turnId: this._turnId,
					requestId: this._requestId,
					gitHubRequestId: this._gitHubRequestId,
					closeCode: event.code,
					closeReason: closeCodeDescription,
					closeEventReason: event.reason,
					closeEventWasClean: String(event.wasClean),
					connectDurationMs,
				});
				reject(new Error('WebSocket closed during connection setup'));