Agents - generate titles for untitled external sessions

src/vs/platform/agentHost/node/agentHostMain.ts

@@ -457,8 +457,13 @@ async function startAgentHost(): Promise<void> {
 		handler => protocolHandlers.push(handler),
 	);
 	configuredWebSocketServer.settleWith(configuredWebSocketServerStart);
+	// Startup is complete once the last ingress has settled — successfully or
+	// not, since a failed WebSocket server is non-fatal. Deferred maintenance
+	// then runs after a client has also been served its first session listing.
 	void configuredWebSocketServerStart.catch(err => {
 		logService.error('Failed to start WebSocket server', err);
+	}).finally(() => {
+		agentService.markStartupComplete();
 	});
 
 	process.once('exit', () => {

src/vs/platform/agentHost/node/agentHostServerMain.ts

@@ -318,6 +318,7 @@ async function main(): Promise<void> {
 	function reportReady(addr: string): void {
 		const listeningPort = Number(addr.split(':').pop());
 		process.stdout.write(`READY:${listeningPort}\n`);
+		agentService.markStartupComplete();
 
 		const urls = resolveServerUrls(options.host, listeningPort);
 		for (const url of urls.local) {

src/vs/platform/agentHost/node/agentHostSessionTitleController.ts

@@ -424,6 +424,38 @@ export class AgentHostSessionTitleController extends Disposable {
 		dispatch(title);
 	}
 
+	/**
+	 * Generates a title for an external session whose provider surfaced it
+	 * without one, from the user's first prompt. Such a session usually has no
+	 * live state (it is materialized when opened), so the generated title is
+	 * persisted and pushed onto its surfaced summary. A session that already
+	 * carries a persisted title keeps it; a rename during generation cancels it.
+	 *
+	 * Unlike the other entry points this awaits generation, so the caller's
+	 * deferred-work lane stays serialized against it.
+	 */
+	async generateExternalSessionTitle(session: ProtocolURI, userPrompt: string): Promise<void> {
+		if (this._isEphemeralSession(session) || await this._readPersistedTitleMetadata(session, SESSION_CUSTOM_TITLE_KEY)) {
+			return;
+		}
+		await this._startTitleGeneration(
+			session,
+			{ content: userPrompt, isConversation: false, gitHubReferenceSource: userPrompt },
+			'',
+			title => this._applyExternalSessionTitle(session, title),
+			() => true,
+			title => this._persistAutoTitle(session, undefined, title),
+		);
+	}
+
+	private _applyExternalSessionTitle(session: ProtocolURI, title: string): void {
+		if (this._stateManager.getSessionState(session)) {
+			this._applySeedTitle(session, undefined, title);
+		} else {
+			this._applyTitle(session, title, t => this._stateManager.updateSurfacedSessionTitle(session, t));
+		}
+	}
+
 	cancelTitleGeneration(session: ProtocolURI): void {
 		this._cancelTitleGeneration(session);
 	}
@@ -468,7 +500,7 @@ export class AgentHostSessionTitleController extends Disposable {
 			return undefined;
 		}
 		const sourceKey = independentChat ? customChatTitleSourceMetadataKey(independentChat) : SESSION_CUSTOM_TITLE_SOURCE_KEY;
-		const source = await this._readPersistedTitleSource(channel, sourceKey);
+		const source = await this._readPersistedTitleMetadata(channel, sourceKey);
 		if (source === AGENT_HOST_TITLE_SOURCE_USER || source === AGENT_HOST_TITLE_SOURCE_AGENT) {
 			this.markTitleRenamed(channel, independentChat);
 			return undefined;
@@ -488,10 +520,22 @@ export class AgentHostSessionTitleController extends Disposable {
 		currentTitleMatchesFallback: () => boolean,
 		persist: (title: string) => void,
 	): void {
+		void this._startTitleGeneration(key, prompt, fallbackTitle, apply, currentTitleMatchesFallback, persist);
+	}
+
+	/** Starts generation and resolves once the title has been applied and persisted. */
+	private _startTitleGeneration(
+		key: ProtocolURI,
+		prompt: ITitlePromptContext,
+		fallbackTitle: string,
+		apply: (title: string) => void,
+		currentTitleMatchesFallback: () => boolean,
+		persist: (title: string) => void,
+	): Promise<void> {
 		this._cancelTitleGeneration(key);
 		const source = new CancellationTokenSource();
 		this._titleGenerationCancellationSources.set(key, source);
-		void this._generateTitle(key, prompt, fallbackTitle, apply, currentTitleMatchesFallback, persist, source.token).catch(err => {
+		return this._generateTitle(key, prompt, fallbackTitle, apply, currentTitleMatchesFallback, persist, source.token).catch(err => {
 			if (!source.token.isCancellationRequested) {
 				this._logService.warn(`[AgentHostSessionTitleController] Failed to apply generated title for ${key}`, err);
 			}
@@ -810,7 +854,7 @@ export class AgentHostSessionTitleController extends Disposable {
 		return this._stateManager.isEphemeralSession(channel);
 	}
 
-	private async _readPersistedTitleSource(session: ProtocolURI, key: string): Promise<string | undefined> {
+	private async _readPersistedTitleMetadata(session: ProtocolURI, key: string): Promise<string | undefined> {
 		try {
 			const ref = await this._options.sessionDataService.tryOpenDatabase?.(URI.parse(session));
 			if (!ref) {
@@ -822,7 +866,7 @@ export class AgentHostSessionTitleController extends Disposable {
 				ref.dispose();
 			}
 		} catch (err) {
-			this._logService.warn(`[AgentHostSessionTitleController] Failed to read title source '${key}'`, err);
+			this._logService.warn(`[AgentHostSessionTitleController] Failed to read title metadata '${key}'`, err);
 			return undefined;
 		}
 	}

src/vs/platform/agentHost/node/agentHostStateManager.ts

@@ -318,20 +318,22 @@ export class AgentHostStateManager extends Disposable {
 				const entry = this._sessionStates.get(session);
 				return entry ? this._toSummary(session, entry) : undefined;
 			},
-			(session, changes) => {
-				this._onDidChangeSessionSummary.fire({ session, changes });
-				if (this._publishedSessionSummaries.has(session)) {
-					this._onDidEmitNotification.fire({
-						type: 'root/sessionSummaryChanged',
-						channel: ROOT_STATE_URI,
-						session,
-						changes,
-					});
-				}
-			},
+			(session, changes) => this._emitSessionSummaryChanged(session, changes),
 		));
 	}
 
+	private _emitSessionSummaryChanged(session: string, changes: SessionSummaryChangedParams['changes']): void {
+		this._onDidChangeSessionSummary.fire({ session, changes });
+		if (this._publishedSessionSummaries.has(session)) {
+			this._onDidEmitNotification.fire({
+				type: 'root/sessionSummaryChanged',
+				channel: ROOT_STATE_URI,
+				session,
+				changes,
+			});
+		}
+	}
+
 	private _emitSessionAdded(summary: SessionSummary): void {
 		if (readEphemeralSessionMeta(summary).isEphemeral) {
 			return;
@@ -817,6 +819,19 @@ export class AgentHostStateManager extends Disposable {
 		this._emitSessionAdded(summary);
 	}
 
+	/**
+	 * Retitles a surfaced session (one with no live state) so clients update it
+	 * in place. Live sessions are retitled through the reducer instead.
+	 */
+	updateSurfacedSessionTitle(session: string, title: string): void {
+		const announced = this._summaryNotifier.getAnnounced(session);
+		if (this._sessionStates.has(session) || !announced || announced.title === title) {
+			return;
+		}
+		this._summaryNotifier.announce(session, { ...announced, title });
+		this._emitSessionSummaryChanged(session, { title });
+	}
+
 	/** Removes a surfaced session without affecting a live session. */
 	retractSurfacedSession(session: string): void {
 		if (this._sessionStates.has(session)) {

src/vs/platform/agentHost/node/agentService.ts

@@ -5,7 +5,7 @@
 
 import { open, unlink, type FileHandle } from 'fs/promises';
 import { decodeBase64, encodeBase64, VSBuffer } from '../../../base/common/buffer.js';
-import { DeferredPromise, disposableTimeout, Limiter, Promises, ResourceQueue } from '../../../base/common/async.js';
+import { Barrier, DeferredPromise, disposableTimeout, Limiter, Promises, ResourceQueue } from '../../../base/common/async.js';
 import { toErrorMessage } from '../../../base/common/errorMessage.js';
 import { Emitter, type Event } from '../../../base/common/event.js';
 import { Disposable, DisposableMap, DisposableResourceMap, DisposableStore, IDisposable, MutableDisposable } from '../../../base/common/lifecycle.js';
@@ -101,7 +101,6 @@ import { IAgentHostChangesetOperationService } from '../common/agentHostChangese
 const SESSION_GC_GRACE_MS = 30_000;
 const DAY_MS = 24 * 60 * 60 * 1000;
 const EXTERNAL_SESSION_MAX_AGE_MS = 30 * DAY_MS;
-const EXTERNAL_SESSION_PRUNE_DELAY_MS = 60_000;
 const RECENT_EXTERNAL_SESSION_LIMIT = 2;
 /** A catalog pass slower than this is logged at info, since it delays every session-list refresh. */
 const SLOW_LIST_SESSIONS_THRESHOLD_MS = 1_000;
@@ -770,7 +769,7 @@ export class AgentService extends Disposable implements IAgentService {
 				reason: AuthRequiredReason.Required,
 			});
 		}));
-		this._scheduleExternalSessionPrune();
+		this._runWhenStartupSettled('external session prune', () => this._pruneStaleExternalSessions());
 	}
 
 	/**
@@ -791,12 +790,46 @@ export class AgentService extends Disposable implements IAgentService {
 		return this._sideEffects.onDidStartTurn;
 	}
 
-	private _scheduleExternalSessionPrune(): void {
-		this._register(disposableTimeout(() => {
-			void this._pruneStaleExternalSessions().catch(error => {
-				this._logService.warn('[AgentService] Failed to prune stale external sessions', error);
-			});
-		}, EXTERNAL_SESSION_PRUNE_DELAY_MS));
+	/** Opens once startup settled: the host finished starting and the first listing was served. */
+	private readonly _startupSettled = new Barrier();
+	private _hostStartupComplete = false;
+	private _firstListingServed = false;
+	/** Serializes deferred work so background maintenance never overlaps. */
+	private _deferredWork = Promise.resolve();
+
+	/**
+	 * Signals that host startup finished. Deferred work runs once this and the
+	 * first session listing have both happened, so background maintenance never
+	 * competes with startup. Called by the process mains; the service owns no
+	 * ambient timer of its own.
+	 */
+	markStartupComplete(): void {
+		this._hostStartupComplete = true;
+		this._openStartupSettled();
+	}
+
+	private _openStartupSettled(): void {
+		if (this._hostStartupComplete && this._firstListingServed) {
+			this._startupSettled.open();
+		}
+	}
+
+	/**
+	 * Runs `work` once startup has settled, serialized behind any deferred work
+	 * queued before it. For maintenance that is fine to run late and must not
+	 * compete with startup — pruning stale external sessions, titling external
+	 * sessions a provider surfaced without a title, and similar.
+	 */
+	private _runWhenStartupSettled(name: string, work: () => Promise<void>): void {
+		this._deferredWork = this._deferredWork
+			.then(() => this._startupSettled.wait())
+			.then(() => this._store.isDisposed ? undefined : work())
+			.catch(error => this._logService.warn(`[AgentService] Deferred work '${name}' failed`, error));
+	}
+
+	/** Test surface: settles once all deferred work queued so far has run. */
+	async whenDeferredWorkSettled(): Promise<void> {
+		await this._deferredWork;
 	}
 
 	private async _pruneStaleExternalSessions(): Promise<void> {
@@ -839,6 +872,60 @@ export class AgentService extends Disposable implements IAgentService {
 		this._logService.info(`[AgentService] pruned ${staleExternalSessions.length} stale external session row(s) older than ${EXTERNAL_SESSION_MAX_AGE_MS / DAY_MS} days`);
 	}
 
+	/** External sessions registered without a provider title, awaiting a generated one. */
+	private readonly _untitledExternalSessions = new Map<string, IAgentSessionMetadata>();
+	private _externalSessionTitlingQueued = false;
+
+	/**
+	 * Queues external sessions whose provider surfaced them without a title.
+	 * Titling is deferred past startup and capped at the
+	 * {@link RECENT_EXTERNAL_SESSION_LIMIT} most recently updated candidates, so
+	 * a large provider catalog cannot trigger a burst of model calls.
+	 */
+	private _scheduleExternalSessionTitles(sessions: readonly IAgentSessionMetadata[]): void {
+		for (const session of sessions) {
+			this._untitledExternalSessions.set(session.session.toString(), session);
+		}
+		if (this._externalSessionTitlingQueued) {
+			return;
+		}
+		this._externalSessionTitlingQueued = true;
+		this._runWhenStartupSettled('external session titles', () => {
+			this._externalSessionTitlingQueued = false;
+			return this._titleUntitledExternalSessions();
+		});
+	}
+
+	/** Titles the most recently updated queued sessions and drops the rest. */
+	private async _titleUntitledExternalSessions(): Promise<void> {
+		const candidates = [...this._untitledExternalSessions.values()]
+			.sort((a, b) => b.modifiedTime - a.modifiedTime)
+			.slice(0, RECENT_EXTERNAL_SESSION_LIMIT);
+		this._untitledExternalSessions.clear();
+		for (const candidate of candidates) {
+			try {
+				await this._generateExternalSessionTitle(candidate);
+			} catch (error) {
+				this._logService.warn(`[AgentService] Failed to title external session ${candidate.session.toString()}`, error);
+			}
+		}
+	}
+
+	/** Titles one external session from the first user prompt of its default chat. */
+	private async _generateExternalSessionTitle(metadata: IAgentSessionMetadata): Promise<void> {
+		const session = metadata.session;
+		const agent = this._findProviderForSession(session);
+		if (!agent) {
+			return;
+		}
+		const chat = URI.parse(buildDefaultChatUri(session));
+		const turns = await agent.chats.getMessages(chat, this._chatContext(session, chat));
+		const prompt = turns[0]?.message.text.trim();
+		if (prompt) {
+			await this._sideEffects.generateExternalSessionTitle(session.toString(), prompt);
+		}
+	}
+
 	// ---- provider registration ----------------------------------------------
 
 	/**
@@ -1581,6 +1668,7 @@ export class AgentService extends Disposable implements IAgentService {
 		let registeredExternal = false;
 		let alreadyRegistered = 0;
 		let registryChanged = false;
+		const untitledExternal: IAgentSessionMetadata[] = [];
 		const results = await Promise.all(chats.map(({ external, ...metadata }) => discoveryLimiter.queue(async () => {
 			const sessionMetadata = this._toSessionMetadata(metadata);
 			const session = sessionMetadata.session;
@@ -1611,6 +1699,9 @@ export class AgentService extends Disposable implements IAgentService {
 						await this._initializeExternalSessionReadState(session);
 					}
 					registeredKeys.add(session.toString());
+					if (external && !sessionMetadata.summary) {
+						untitledExternal.push(sessionMetadata);
+					}
 					if (external && !readSessionEhcliAdoptable(sessionMetadata._meta)) {
 						registeredExternal = true;
 					} else {
@@ -1632,6 +1723,9 @@ export class AgentService extends Disposable implements IAgentService {
 		if (registeredExternal) {
 			this._queueSessionListReconciliation();
 		}
+		if (untitledExternal.length > 0) {
+			this._scheduleExternalSessionTitles(untitledExternal);
+		}
 		this._logService.info(`[AgentService] discovery for provider ${provider.id}: ${chats.length} candidate(s) (${chats.filter(chat => chat.external).length} external), ${registered} registered, ${alreadyRegistered} already registered, ${suppressed} suppressed as subagent/chat backing, ${skippedAsStale} skipped as older than ${EXTERNAL_SESSION_MAX_AGE_MS / DAY_MS} days`);
 		return registered > 0;
 	}
@@ -1664,6 +1758,7 @@ export class AgentService extends Disposable implements IAgentService {
 			return { session: s.session, provider: provider.id, startTime: s.startTime, external, source: external ? 'discovery' : 'restore' };
 		})));
 		let registeredExternal = false;
+		const untitledExternal: IAgentSessionMetadata[] = [];
 		for (let index = 0; index < identities.length; index++) {
 			const identity = identities[index];
 			if (!identity) {
@@ -1680,6 +1775,9 @@ export class AgentService extends Disposable implements IAgentService {
 					await this._initializeExternalSessionReadState(identity.session);
 				}
 				existing.set(identity.session.toString(), identity.external);
+				if (identity.external && !metadata.summary) {
+					untitledExternal.push(metadata);
+				}
 				if (identity.external && !readSessionEhcliAdoptable(metadata._meta)) {
 					registeredExternal = true;
 				} else {
@@ -1691,6 +1789,9 @@ export class AgentService extends Disposable implements IAgentService {
 		if (registeredExternal) {
 			this._queueSessionListReconciliation();
 		}
+		if (untitledExternal.length > 0) {
+			this._scheduleExternalSessionTitles(untitledExternal);
+		}
 	}
 
 	/** Seeds external sessions as read. Avoiding this DB requires a durable registry default. */
@@ -1829,7 +1930,16 @@ export class AgentService extends Disposable implements IAgentService {
 				this._inFlightListSessions.delete(mode);
 			}
 		};
-		void promise.then(clear, clear);
+		void promise.then(
+			() => {
+				clear();
+				// Only a served listing ends startup: a failed one is retried, and
+				// deferred work must not compete with that retry.
+				this._firstListingServed = true;
+				this._openStartupSettled();
+			},
+			clear,
+		);
 		return [...await promise];
 	}
 
@@ -6866,6 +6976,9 @@ export class AgentService extends Disposable implements IAgentService {
 	}
 
 	override dispose(): void {
+		// Unblocks pending deferred work so its chain drains; the disposal guard
+		// in `_runWhenStartupSettled` keeps the work itself from running.
+		this._startupSettled.open();
 		for (const provider of this._providers.values()) {
 			provider.dispose();
 		}