Replace requestKind literal strings with RequestKind constant

Collapse the four IBackgroundRequestOptions / ISubagentRequestOptions /
ISummarizationRequestOptions / IMainAgentRequestOptions interfaces into
a single 'as const' object + derived type, matching the existing
ToolName / ContributedToolName pattern in this codebase. Call sites now
use RequestKind.MainAgent etc. instead of hand-typing 'mainagent', so a
future rename only has to update the RequestKind definition.

Compile-time safety is unchanged — IRequestKindOptions.kind is still
typed as the union of literals.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

extensions/copilot/src/extension/inlineChat/node/inlineChatIntent.ts

@@ -17,7 +17,7 @@ import { IOctoKitService } from '../../../platform/github/common/githubService';
 import { IIgnoreService } from '../../../platform/ignore/common/ignoreService';
 import { ILogService } from '../../../platform/log/common/logService';
 import { Prediction } from '../../../platform/networking/common/fetch';
-import { IChatEndpoint, IMakeChatRequestOptions } from '../../../platform/networking/common/networking';
+import { IChatEndpoint, IMakeChatRequestOptions, RequestKind } from '../../../platform/networking/common/networking';
 import { IParserService } from '../../../platform/parser/node/parserService';
 import { getWasmLanguage } from '../../../platform/parser/node/treeSitterLanguages';
 import { IExperimentationService } from '../../../platform/telemetry/common/nullExperimentationService';
@@ -468,7 +468,7 @@ class InlineChatEditToolsStrategy implements IInlineChatEditStrategy {
 				conversationId: telemetry.sessionId,
 				messageSource: this._intent.id
 			},
-			requestKindOptions: { kind: 'mainagent' },
+			requestKindOptions: { kind: RequestKind.MainAgent },
 			finishedCb: async (_text, _index, delta) => {
 
 				telemetry.markReceivedToken();
@@ -668,7 +668,7 @@ class InlineChatEditHeuristicStrategy implements IInlineChatEditStrategy {
 				conversationId: telemetry.sessionId,
 				messageSource: this._intent.id
 			},
-			requestKindOptions: { kind: 'mainagent' },
+			requestKindOptions: { kind: RequestKind.MainAgent },
 			requestOptions: {
 				stream: true,
 				prediction

extensions/copilot/src/extension/intents/node/agentIntent.ts

@@ -19,7 +19,7 @@ import { IEnvService } from '../../../platform/env/common/envService';
 import { ILogService } from '../../../platform/log/common/logService';
 import { IEditLogService } from '../../../platform/multiFileEdit/common/editLogService';
 import { CUSTOM_TOOL_SEARCH_NAME, isAnthropicContextEditingEnabled } from '../../../platform/networking/common/anthropic';
-import { IChatEndpoint } from '../../../platform/networking/common/networking';
+import { IChatEndpoint, RequestKind } from '../../../platform/networking/common/networking';
 import { modelsWithoutResponsesContextManagement } from '../../../platform/networking/common/openai';
 import { INotebookService } from '../../../platform/notebook/common/notebookService';
 import { GenAiMetrics } from '../../../platform/otel/common/genAiMetrics';
@@ -864,7 +864,7 @@ export class AgentIntentInvocation extends EditCodeIntentInvocation implements I
 						modelCapabilities,
 						telemetryProperties: associatedRequestId ? { associatedRequestId } : undefined,
 						enableRetryOnFilter: true,
-						requestKindOptions: { kind: 'summarization' },
+						requestKindOptions: { kind: RequestKind.Summarization },
 					}, bgToken);
 					if (response.type !== ChatFetchResponseType.Success) {
 						throw new Error(`Background inline summarization request failed: ${response.type}`);

extensions/copilot/src/extension/prompt/node/chatMLFetcher.ts

@@ -21,7 +21,7 @@ import { getResponsesApiCompactionThresholdFromBody, OpenAIResponsesProcessor, r
 import { collectSingleLineErrorMessage, ILogService } from '../../../platform/log/common/logService';
 import { FinishedCallback, getRequestId, IResponseDelta, OptionalChatRequestParams, RequestId } from '../../../platform/networking/common/fetch';
 import { FetcherId, IFetcherService, Response } from '../../../platform/networking/common/fetcherService';
-import { IChatEndpoint, IEndpointBody, IRequestKindOptions, postRequest, stringifyUrlOrRequestMetadata } from '../../../platform/networking/common/networking';
+import { IChatEndpoint, IEndpointBody, IRequestKindOptions, postRequest, RequestKind, stringifyUrlOrRequestMetadata } from '../../../platform/networking/common/networking';
 import { CAPIChatMessage, ChatCompletion, FilterReason, FinishedCompletionReason, rawMessageToCAPI } from '../../../platform/networking/common/openai';
 import { sendEngineMessagesTelemetry } from '../../../platform/networking/node/chatStream';
 import { CAPIWebSocketErrorEvent, IChatWebSocketManager, isCAPIWebSocketError } from '../../../platform/networking/node/chatWebSocketManager';
@@ -142,7 +142,7 @@ export class ChatMLFetcherImpl extends AbstractChatMLFetcher {
 		// explicitly opt in to 'mainagent'. This way new utility callers get classified
 		// correctly without each one having to remember to opt in.
 		if (!requestKindOptions) {
-			requestKindOptions = { kind: 'background' };
+			requestKindOptions = { kind: RequestKind.Background };
 		}
 		if (useWebSocket && this._consecutiveWebSocketRetryFallbacks >= ChatMLFetcherImpl._maxConsecutiveWebSocketFallbacks) {
 			this._logService.debug(`[ChatWebSocketManager] Disabling WebSocket for request due to ${this._consecutiveWebSocketRetryFallbacks} consecutive WebSocket failures with successful HTTP fallback.`);
@@ -1076,9 +1076,9 @@ export class ChatMLFetcherImpl extends AbstractChatMLFetcher {
 		summarizedAtRoundId: string | undefined,
 	): Promise<{ result: ChatResults | ChatRequestFailed | ChatRequestCanceled }> {
 		const intent = locationToIntent(location);
-		const agentInteractionType = requestKindOptions?.kind === 'subagent' ?
+		const agentInteractionType = requestKindOptions?.kind === RequestKind.Subagent ?
 			'conversation-subagent' :
-			requestKindOptions?.kind === 'background' ?
+			requestKindOptions?.kind === RequestKind.Background ?
 				'conversation-background' :
 				intent === 'conversation-agent' ? intent : undefined;
 		const additionalHeaders: Record<string, string> = {

extensions/copilot/src/extension/prompt/node/chatMLFetcherTelemetry.ts

@@ -6,7 +6,7 @@
 import { ChatFetchError } from '../../../platform/chat/common/commonTypes';
 import { isAutoModel } from '../../../platform/endpoint/node/autoChatEndpoint';
 import { FetcherId } from '../../../platform/networking/common/fetcherService';
-import { IChatEndpoint, IChatRequestTelemetryProperties, IEndpointBody, IRequestKindOptions } from '../../../platform/networking/common/networking';
+import { IChatEndpoint, IChatRequestTelemetryProperties, IEndpointBody, IRequestKindOptions, RequestKind } from '../../../platform/networking/common/networking';
 import { ChatCompletion } from '../../../platform/networking/common/openai';
 import { ITelemetryService } from '../../../platform/telemetry/common/telemetry';
 import { TelemetryData } from '../../../platform/telemetry/common/telemetryData';
@@ -160,7 +160,7 @@ export class ChatMLFetcherTelemetrySender {
 			filterReason: chatCompletion.filterReason,
 			source: baseTelemetry?.properties.messageSource ?? 'unknown',
 			initiatorType: userInitiatedRequest ? 'user' : 'agent',
-			requestKind: requestKindOptions?.kind ?? 'mainagent',
+			requestKind: requestKindOptions?.kind ?? RequestKind.MainAgent,
 			conversationId: baseTelemetry?.properties.conversationId,
 			model: chatEndpointInfo?.model,
 			modelInvoked: chatCompletion.model,
@@ -277,7 +277,7 @@ export class ChatMLFetcherTelemetrySender {
 			source,
 			requestId,
 			model,
-			requestKind: requestKindOptions?.kind ?? 'mainagent',
+			requestKind: requestKindOptions?.kind ?? RequestKind.MainAgent,
 			conversationId,
 			associatedRequestId,
 			parentRequestId,
@@ -371,7 +371,7 @@ export class ChatMLFetcherTelemetrySender {
 			type: processed.type,
 			reason: processed.reasonDetail || processed.reason,
 			source: telemetryProperties?.messageSource ?? 'unknown',
-			requestKind: requestKindOptions?.kind ?? 'mainagent',
+			requestKind: requestKindOptions?.kind ?? RequestKind.MainAgent,
 			conversationId: telemetryProperties?.conversationId,
 			requestId: processed.requestId,
 			gitHubRequestId: processed.serverRequestId,

extensions/copilot/src/extension/prompt/node/defaultIntentRequestHandler.ts

@@ -23,6 +23,7 @@ import { HAS_IGNORED_FILES_MESSAGE } from '../../../platform/ignore/common/ignor
 import { ILogService } from '../../../platform/log/common/logService';
 import { isAnthropicContextEditingEnabled } from '../../../platform/networking/common/anthropic';
 import { FilterReason } from '../../../platform/networking/common/openai';
+import { RequestKind } from '../../../platform/networking/common/networking';
 import { IOTelService } from '../../../platform/otel/common/otelService';
 import { CapturingToken } from '../../../platform/requestLogger/common/capturingToken';
 import { IRequestLogger } from '../../../platform/requestLogger/common/requestLogger';
@@ -731,8 +732,8 @@ class DefaultToolCallingLoop extends ToolCallingLoop<IDefaultToolLoopOptions> {
 				parentRequestId: this.options.request.parentRequestId,
 			},
 			requestKindOptions: this.options.request.subAgentInvocationId
-				? { kind: 'subagent' }
-				: { kind: 'mainagent' },
+				? { kind: RequestKind.Subagent }
+				: { kind: RequestKind.MainAgent },
 			enableRetryOnFilter: true
 		}, token);
 	}

extensions/copilot/src/extension/prompt/node/executionSubagentToolCallingLoop.ts

@@ -13,6 +13,7 @@ import { ConfigKey, IConfigurationService } from '../../../platform/configuratio
 import { ChatEndpointFamily, IEndpointProvider } from '../../../platform/endpoint/common/endpointProvider';
 import { ProxyAgenticEndpoint } from '../../../platform/endpoint/node/proxyAgenticEndpoint';
 import { IFileSystemService } from '../../../platform/filesystem/common/fileSystemService';
+import { RequestKind } from '../../../platform/networking/common/networking';
 import { IGitService } from '../../../platform/git/common/gitService';
 import { ILogService } from '../../../platform/log/common/logService';
 import { IOTelService } from '../../../platform/otel/common/otelService';
@@ -154,7 +155,7 @@ export class ExecutionSubagentToolCallingLoop extends ToolCallingLoop<IExecution
 			},
 			// This loop is inside a tool called from another request, so never user initiated
 			userInitiatedRequest: false,
-			requestKindOptions: { kind: 'subagent' },
+			requestKindOptions: { kind: RequestKind.Subagent },
 			telemetryProperties: {
 				requestId: this.options.subAgentInvocationId,
 				messageId: randomUUID(),

extensions/copilot/src/extension/prompt/node/searchSubagentToolCallingLoop.ts

@@ -13,6 +13,7 @@ import { ConfigKey, IConfigurationService } from '../../../platform/configuratio
 import { ChatEndpointFamily, IEndpointProvider } from '../../../platform/endpoint/common/endpointProvider';
 import { ProxyAgenticEndpoint } from '../../../platform/endpoint/node/proxyAgenticEndpoint';
 import { IFileSystemService } from '../../../platform/filesystem/common/fileSystemService';
+import { RequestKind } from '../../../platform/networking/common/networking';
 import { IGitService } from '../../../platform/git/common/gitService';
 import { ILogService } from '../../../platform/log/common/logService';
 import { IOTelService } from '../../../platform/otel/common/otelService';
@@ -165,7 +166,7 @@ export class SearchSubagentToolCallingLoop extends ToolCallingLoop<ISearchSubage
 				conversationId: this.options.conversation.sessionId,
 				parentToolCallId: this.options.parentToolCallId,
 			},
-			requestKindOptions: { kind: 'subagent' }
+			requestKindOptions: { kind: RequestKind.Subagent }
 		}, token);
 	}
 }

extensions/copilot/src/extension/prompt/node/summarizer.ts

@@ -12,6 +12,7 @@ import { CapturingToken } from '../../../platform/requestLogger/common/capturing
 import { IRequestLogger } from '../../../platform/requestLogger/common/requestLogger';
 import { URI } from '../../../util/vs/base/common/uri';
 import { IInstantiationService } from '../../../util/vs/platform/instantiation/common/instantiation';
+import { RequestKind } from '../../../platform/networking/common/networking';
 import { ConversationHistorySummarizationPrompt } from '../../prompts/node/agent/summarizedConversationHistory';
 import { renderPromptElement } from '../../prompts/node/base/promptRenderer';
 import { ChatVariablesCollection } from '../common/chatVariablesCollection';
@@ -96,7 +97,7 @@ export class ChatSummarizerProvider implements vscode.ChatSummarizer {
 			finishedCb: undefined,
 			location: ChatLocation.Panel,
 			userInitiatedRequest: false,
-			requestKindOptions: { kind: 'summarization' },
+			requestKindOptions: { kind: RequestKind.Summarization },
 		}, token));
 
 		if (token.isCancellationRequested) {

extensions/copilot/src/extension/prompts/node/agent/summarizedConversationHistory.tsx

@@ -16,7 +16,7 @@ import { ConfigKey, IConfigurationService } from '../../../../platform/configura
 import { isAnthropicFamily, isGeminiFamily } from '../../../../platform/endpoint/common/chatModelCapabilities';
 import { ILogService } from '../../../../platform/log/common/logService';
 import { CUSTOM_TOOL_SEARCH_NAME } from '../../../../platform/networking/common/anthropic';
-import { IChatEndpoint } from '../../../../platform/networking/common/networking';
+import { IChatEndpoint, RequestKind } from '../../../../platform/networking/common/networking';
 import { APIUsage } from '../../../../platform/networking/common/openai';
 import { IPromptPathRepresentationService } from '../../../../platform/prompts/common/promptPathRepresentationService';
 import { ITelemetryService } from '../../../../platform/telemetry/common/telemetry';
@@ -750,7 +750,7 @@ class ConversationHistorySummarizer {
 				},
 				telemetryProperties: associatedRequestId ? { associatedRequestId } : undefined,
 				enableRetryOnFilter: true,
-				requestKindOptions: { kind: 'summarization' }
+				requestKindOptions: { kind: RequestKind.Summarization }
 			}, this.token ?? CancellationToken.None);
 		} catch (e) {
 			this.logInfo(`Error from summarization request. ${e.message}`, mode);

extensions/copilot/src/platform/networking/common/networking.ts

@@ -355,39 +355,30 @@ export interface INetworkRequestOptions {
 }
 
 /**
- * A background request is one that is not associated with a user request.
+ * Classifies a chat request for telemetry (`requestKind` on response events) and the
+ * `X-Interaction-Type` header sent to CAPI.
+ *
+ * - `Background`: out-of-band utility request not directly tied to a user turn (default).
+ * - `Subagent`: a request made by a subagent loop (search/execution); also indicated to
+ *   the server with `X-Interaction-Type: conversation-subagent`.
+ * - `Summarization`: conversation-history compaction in the critical path of a user turn.
+ * - `MainAgent`: a primary user-initiated chat turn (panel chat, inline chat).
+ *
+ * Callers opt in to a non-default kind via `RequestKind.<Member>`. Anything that doesn't
+ * set `requestKindOptions` is classified as `RequestKind.Background` by `chatMLFetcher`.
  */
-export interface IBackgroundRequestOptions {
-	readonly kind: 'background';
-}
+export const RequestKind = {
+	Background: 'background',
+	Subagent: 'subagent',
+	Summarization: 'summarization',
+	MainAgent: 'mainagent',
+} as const;
+export type RequestKind = typeof RequestKind[keyof typeof RequestKind];
 
-/**
- * A subagent request is a request made by a subagent, indicated with a subAgentInvocationId included in the request from VS Code.
- */
-export interface ISubagentRequestOptions {
-	readonly kind: 'subagent';
+export interface IRequestKindOptions {
+	readonly kind: RequestKind;
 }
 
-/**
- * A summarization request — used for compacting conversation history (both
- * inline mid-turn and post-turn). Distinct from 'background' because it's
- * directly in the critical path of a user turn.
- */
-export interface ISummarizationRequestOptions {
-	readonly kind: 'summarization';
-}
-
-/**
- * A normal request is a primary user-initiated chat turn (e.g. driven by the
- * default intent request handler or inline chat). Callers explicitly opt in to
- * 'mainagent' so the chat ML fetcher can default unmarked requests to 'background'.
- */
-export interface IMainAgentRequestOptions {
-	readonly kind: 'mainagent';
-}
-
-export type IRequestKindOptions = IBackgroundRequestOptions | ISubagentRequestOptions | ISummarizationRequestOptions | IMainAgentRequestOptions;
-
 function networkRequest(
 	accessor: ServicesAccessor,
 	options: INetworkRequestOptions,
@@ -409,9 +400,9 @@ function networkRequest(
 		name: '',
 		version: '',
 	} satisfies IEndpoint : endpointOrUrl;
-	const agentInteractionType = options.requestKindOptions?.kind === 'subagent' ?
+	const agentInteractionType = options.requestKindOptions?.kind === RequestKind.Subagent ?
 		'conversation-subagent' :
-		options.requestKindOptions?.kind === 'background' ?
+		options.requestKindOptions?.kind === RequestKind.Background ?
 			'conversation-background' :
 			intent === 'conversation-agent' ? intent :
 				intent;