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roblourens merged 4 commits into from
May 8, 2026
Merged

Derive worktree branch name from first message on agent host #315065

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e8f337d
Derive worktree branch name from first message on agent host
roblourens May 7, 2026
8d38130
Add unit tests for getCopilotBranchNameHintFromMessage
roblourens May 7, 2026
4f23009
Merge remote-tracking branch 'origin/main' into agents/be796a2d-16df-…
roblourens May 7, 2026
d116f50
Fix possibly-undefined access in branch name hint test
roblourens May 7, 2026
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2 changes: 0 additions & 2 deletions src/vs/platform/agentHost/common/sessionConfigKeys.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,6 @@ export const enum SessionConfigKey {
Isolation = 'isolation',
/** `'branch'` — base branch to work from. */
Branch = 'branch',
/** `'branchNameHint'` — client-supplied hint used during worktree creation. */
BranchNameHint = 'branchNameHint',
/** `'mode'` — agent execution mode (interactive / plan). */
Mode = 'mode',
}
Expand Down
37 changes: 30 additions & 7 deletions src/vs/platform/agentHost/node/copilot/copilotAgent.ts
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Expand Up @@ -139,6 +139,28 @@ export function getCopilotWorktreeBranchName(sessionId: string, branchNameHint:
return `agents/${branchNameHint ? `${branchNameHint}-${sessionId.substring(0, 8)}` : sessionId}`;
}

/**
* Derive a slug-style branch-name hint from the user's first message. Used
* by the worktree isolation flow so the generated branch name reflects the
* intent of the session instead of being just a session id.
*
* Returns `undefined` if the message has no slug-able content (e.g. only
* punctuation), in which case the caller falls back to a session-id-only
* branch name.
*/
export function getCopilotBranchNameHintFromMessage(message: string): string | undefined {
const words = message
.toLowerCase()
.normalize('NFKD')
.replace(/[^a-z0-9]+/g, '-')
.replace(/^-+|-+$/g, '')
.split('-')
.filter(word => word.length > 0)
.slice(0, 8);
const hint = words.join('-').slice(0, 48).replace(/-+$/g, '');
return hint.length > 0 ? hint : undefined;
}
Comment thread
roblourens marked this conversation as resolved.

/**
* Builds the localized "Created isolated worktree for branch X" markdown
* shown at the top of the first response in worktree-isolated sessions.
Expand Down Expand Up @@ -761,7 +783,7 @@ export class CopilotAgent extends Disposable implements IAgent {
* `SessionConfigChanged` actions that arrived after `createSession` are
* honoured without bespoke forwarding.
*/
private async _materializeProvisional(sessionId: string): Promise<CopilotAgentSession> {
private async _materializeProvisional(sessionId: string, prompt: string): Promise<CopilotAgentSession> {
const provisional = this._provisionalSessions.get(sessionId);
if (!provisional) {
throw new Error(`Cannot materialize unknown provisional session: ${sessionId}`);
Expand All @@ -781,7 +803,7 @@ export class CopilotAgent extends Disposable implements IAgent {
const customizationDirectory = provisional.workingDirectory;
const activeClient = this._activeClients.get(sessionUri);
const snapshot = activeClient ? await activeClient.snapshot(customizationDirectory) : undefined;
const workingDirectory = await this._resolveSessionWorkingDirectory(materializedConfig, sessionId);
const workingDirectory = await this._resolveSessionWorkingDirectory(materializedConfig, sessionId, prompt);
const shellManager = this._instantiationService.createInstance(ShellManager, sessionUri, workingDirectory);
const sessionConfigBuilder = this._buildSessionConfig(snapshot, shellManager);

Expand Down Expand Up @@ -920,10 +942,12 @@ export class CopilotAgent extends Disposable implements IAgent {
await this._sessionSequencer.queue(sessionId, async () => {

// First message on a provisional session: materialize the SDK
// session, worktree, and on-disk metadata before continuing.
// session, worktree, and on-disk metadata before continuing. The
// prompt is forwarded so a worktree-isolated session can derive
// its branch-name hint from the user's first message.
let entry: CopilotAgentSession | undefined;
if (this._provisionalSessions.has(sessionId)) {
entry = await this._materializeProvisional(sessionId);
entry = await this._materializeProvisional(sessionId, prompt);
} else {
entry = this._sessions.get(sessionId);
}
Expand Down Expand Up @@ -1430,7 +1454,7 @@ export class CopilotAgent extends Disposable implements IAgent {
return this._gitService.getBranches(workingDirectory, { query, limit: CopilotAgent._BRANCH_COMPLETION_LIMIT });
}

protected async _resolveSessionWorkingDirectory(config: IAgentCreateSessionConfig | undefined, sessionId: string): Promise<URI | undefined> {
protected async _resolveSessionWorkingDirectory(config: IAgentCreateSessionConfig | undefined, sessionId: string, prompt?: string): Promise<URI | undefined> {
if (config?.config?.isolation !== 'worktree' || !config.workingDirectory || typeof config.config.branch !== 'string') {
return config?.workingDirectory;
}
Expand All @@ -1441,8 +1465,7 @@ export class CopilotAgent extends Disposable implements IAgent {
}

const worktreesRoot = getCopilotWorktreesRoot(repositoryRoot);
const branchNameHintRaw = config.config[SessionConfigKey.BranchNameHint];
const branchNameHint = typeof branchNameHintRaw === 'string' ? branchNameHintRaw : undefined;
const branchNameHint = prompt ? getCopilotBranchNameHintFromMessage(prompt) : undefined;
const branchName = getCopilotWorktreeBranchName(sessionId, branchNameHint);
const worktree = URI.joinPath(worktreesRoot, getCopilotWorktreeName(branchName));
await fs.mkdir(worktreesRoot.fsPath, { recursive: true });
Expand Down
28 changes: 19 additions & 9 deletions src/vs/platform/agentHost/test/node/copilotAgent.test.ts
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Expand Up @@ -29,7 +29,7 @@ import { AgentConfigurationService, IAgentConfigurationService } from '../../nod
import { AgentHostStateManager } from '../../node/agentHostStateManager.js';
import { IAgentHostGitService } from '../../node/agentHostGitService.js';
import { IAgentHostTerminalManager } from '../../node/agentHostTerminalManager.js';
import { CopilotAgent, getCopilotWorktreeBranchName, getCopilotWorktreeName, getCopilotWorktreesRoot } from '../../node/copilot/copilotAgent.js';
import { CopilotAgent, getCopilotBranchNameHintFromMessage, getCopilotWorktreeBranchName, getCopilotWorktreeName, getCopilotWorktreesRoot } from '../../node/copilot/copilotAgent.js';
import { CopilotAgentSession, type SessionWrapperFactory } from '../../node/copilot/copilotAgentSession.js';
import { CopilotSessionWrapper } from '../../node/copilot/copilotSessionWrapper.js';
import { ShellManager } from '../../node/copilot/copilotShellTools.js';
Expand Down Expand Up @@ -273,8 +273,8 @@ class TestableCopilotAgent extends CopilotAgent {
return stub;
}

resolveWorktreeForTest(config: Parameters<CopilotAgent['createSession']>[0], sessionId: string): Promise<URI | undefined> {
return this._resolveSessionWorkingDirectory(config, sessionId);
resolveWorktreeForTest(config: Parameters<CopilotAgent['createSession']>[0], sessionId: string, prompt?: string): Promise<URI | undefined> {
return this._resolveSessionWorkingDirectory(config, sessionId, prompt);
}
}

Expand Down Expand Up @@ -372,6 +372,16 @@ suite('CopilotAgent', () => {
assert.strictEqual(getCopilotWorktreeBranchName('12345678-aaaa-bbbb-cccc-123456789abc', 'a'.repeat(48)).length, 'agents/'.length + 48 + '-12345678'.length);
});

test('derives slug branch hint from first message', () => {
assert.strictEqual(getCopilotBranchNameHintFromMessage('Add agent host config'), 'add-agent-host-config');
assert.strictEqual(getCopilotBranchNameHintFromMessage(' Fix: the bug!! '), 'fix-the-bug');
assert.strictEqual(getCopilotBranchNameHintFromMessage('Refactor café ☕ rendering'), 'refactor-cafe-rendering');
assert.strictEqual(getCopilotBranchNameHintFromMessage('one two three four five six seven eight nine ten'), 'one-two-three-four-five-six-seven-eight');
assert.strictEqual(getCopilotBranchNameHintFromMessage('a'.repeat(100))?.length, 48);
assert.strictEqual(getCopilotBranchNameHintFromMessage('!!! ??? ...'), undefined);
assert.strictEqual(getCopilotBranchNameHintFromMessage(''), undefined);
});

test('returns empty models and throws AuthRequired for sessions before authentication', async () => {
const agent = createTestAgent(disposables);
try {
Expand Down Expand Up @@ -824,8 +834,8 @@ suite('CopilotAgent', () => {
const expectedBranchName = getCopilotWorktreeBranchName(sessionId, branchHint);
const workingDir = await agent.resolveWorktreeForTest({
workingDirectory: repositoryRoot,
config: { isolation: 'worktree', branch: 'main', branchNameHint: branchHint },
}, sessionId);
config: { isolation: 'worktree', branch: 'main' },
}, sessionId, 'Add feature');
assert.ok(workingDir, 'resolveWorktreeForTest must return a worktree URI');
assert.deepStrictEqual(gitService.addedWorktrees.length, 1, 'addWorktree must be called once');
assert.strictEqual(gitService.addedWorktrees[0].branchName, expectedBranchName);
Expand Down Expand Up @@ -950,7 +960,7 @@ suite('CopilotAgent', () => {
await agent.authenticate('https://api.github.com', 'token');
const workingDir = await agent.resolveWorktreeForTest({
workingDirectory: repositoryRoot,
config: { isolation: 'worktree', branch: 'main', branchNameHint: 'feat' },
config: { isolation: 'worktree', branch: 'main' },
}, sessionId);
assert.ok(workingDir, 'worktree must be created');
// Simulate the worktree directory existing on disk so the archive
Expand Down Expand Up @@ -997,7 +1007,7 @@ suite('CopilotAgent', () => {
await agent.authenticate('https://api.github.com', 'token');
const workingDir = await agent.resolveWorktreeForTest({
workingDirectory: repositoryRoot,
config: { isolation: 'worktree', branch: 'main', branchNameHint: 'feat' },
config: { isolation: 'worktree', branch: 'main' },
}, sessionId);
await fs.mkdir(workingDir!.fsPath, { recursive: true });
gitService.dirtyWorkingDirectories.add(workingDir!.fsPath);
Expand Down Expand Up @@ -1028,7 +1038,7 @@ suite('CopilotAgent', () => {
await agent.authenticate('https://api.github.com', 'token');
const workingDir = await agent.resolveWorktreeForTest({
workingDirectory: repositoryRoot,
config: { isolation: 'worktree', branch: 'main', branchNameHint: 'feat' },
config: { isolation: 'worktree', branch: 'main' },
}, sessionId);
await fs.mkdir(workingDir!.fsPath, { recursive: true });
// Drop the branch so cleanup must skip.
Expand Down Expand Up @@ -1083,7 +1093,7 @@ suite('CopilotAgent', () => {
await agent.authenticate('https://api.github.com', 'token');
const workingDir = await agent.resolveWorktreeForTest({
workingDirectory: repositoryRoot,
config: { isolation: 'worktree', branch: 'main', branchNameHint: 'feat' },
config: { isolation: 'worktree', branch: 'main' },
}, sessionId);
await fs.mkdir(workingDir!.fsPath, { recursive: true });

Expand Down
3 changes: 0 additions & 3 deletions src/vs/sessions/contrib/chat/browser/agentHost/agentHostSessionConfigPicker.ts
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Expand Up @@ -305,9 +305,6 @@ export class AgentHostSessionConfigPicker extends Disposable {
const properties = this._orderProperties(Object.entries(resolvedConfig.schema.properties));

for (const [property, schema] of properties) {
if (property === SessionConfigKey.BranchNameHint) {
continue;
}
// Only render pickers for properties we know how to present. Today
// that's string properties with either a static `enum` or a
// dynamic enum sourced via `getSessionConfigCompletions`.
Expand Down
2 changes: 1 addition & 1 deletion src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostChatContribution.ts
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Expand Up @@ -35,7 +35,7 @@ import { AgentHostSessionListController } from './agentHostSessionListController
import { LoggingAgentConnection } from './loggingAgentConnection.js';
import { SyncedCustomizationBundler } from './syncedCustomizationBundler.js';

export { AgentHostSessionHandler, getAgentHostBranchNameHint } from './agentHostSessionHandler.js';
export { AgentHostSessionHandler } from './agentHostSessionHandler.js';
export { AgentHostSessionListController } from './agentHostSessionListController.js';

/**
Expand Down
20 changes: 2 additions & 18 deletions src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostSessionHandler.ts
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Expand Up @@ -18,7 +18,6 @@ import { isLocation, type Location } from '../../../../../../editor/common/langu
import { IPosition } from '../../../../../../editor/common/core/position.js';
import { localize } from '../../../../../../nls.js';
import { AgentProvider, AgentSession, type IAgentConnection } from '../../../../../../platform/agentHost/common/agentService.js';
import { SessionConfigKey } from '../../../../../../platform/agentHost/common/sessionConfigKeys.js';
import { IAgentSubscription, observableFromSubscription } from '../../../../../../platform/agentHost/common/state/agentSubscription.js';
import { SessionTruncatedAction } from '../../../../../../platform/agentHost/common/state/protocol/actions.js';
import { CompletionItemKind as AhpCompletionItemKind, type CompletionItem as AhpCompletionItem } from '../../../../../../platform/agentHost/common/state/protocol/commands.js';
Expand Down Expand Up @@ -336,19 +335,6 @@ export interface IAgentHostSessionHandlerConfig {
readonly customizations?: IObservable<CustomizationRef[]>;
}

export function getAgentHostBranchNameHint(message: string): string | undefined {
const words = message
.toLowerCase()
.normalize('NFKD')
.replace(/[^a-z0-9]+/g, '-')
.replace(/^-+|-+$/g, '')
.split('-')
.filter(word => word.length > 0)
.slice(0, 8);
const hint = words.join('-').slice(0, 48).replace(/-+$/g, '');
return hint.length > 0 ? hint : undefined;
}

/**
* Converts a UTF-16 code-unit offset in `text` to a 1-based Monaco
* `IPosition`. Used to translate AHP completion-item ranges (which use
Expand All @@ -368,7 +354,6 @@ function offsetToPosition(text: string, offset: number): IPosition {
}
return { lineNumber, column };
}

export class AgentHostSessionHandler extends Disposable implements IChatSessionContentProvider {

private readonly _activeSessions = new ResourceMap<AgentHostChatSession>();
Expand Down Expand Up @@ -744,7 +729,7 @@ export class AgentHostSessionHandler extends Disposable implements IChatSessionC
// folder-pick time, or this session was created via a legacy/
// test path). Fall back to the original create-then-subscribe
// flow.
await this._createAndSubscribe(request.sessionResource, this._createModelSelection(request.userSelectedModelId, request.modelConfiguration), undefined, request.agentHostSessionConfig, getAgentHostBranchNameHint(request.message));
await this._createAndSubscribe(request.sessionResource, this._createModelSelection(request.userSelectedModelId, request.modelConfiguration), undefined, request.agentHostSessionConfig);
} else {
// Eager-created session: take a refcounted subscription so the
// handler observes state changes for the duration of the chat
Expand Down Expand Up @@ -2285,8 +2270,7 @@ export class AgentHostSessionHandler extends Disposable implements IChatSessionC
}

/** Creates a new backend session and subscribes to its state. */
private async _createAndSubscribe(sessionResource: URI, model: ModelSelection | undefined, fork?: { session: URI; turnIndex: number; turnId: string }, sessionConfig?: Record<string, unknown>, branchNameHint?: string): Promise<URI> {
const config = branchNameHint ? { ...sessionConfig, [SessionConfigKey.BranchNameHint]: branchNameHint } : sessionConfig;
private async _createAndSubscribe(sessionResource: URI, model: ModelSelection | undefined, fork?: { session: URI; turnIndex: number; turnId: string }, config?: Record<string, unknown>): Promise<URI> {
const workingDirectory = this._resolveRequestedWorkingDirectory(sessionResource);
const requestedSession = fork ? undefined : this._resolveSessionUri(sessionResource);

Expand Down
57 changes: 41 additions & 16 deletions src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostChatContribution.test.ts
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Expand Up @@ -36,7 +36,7 @@ import { IProductService } from '../../../../../../platform/product/common/produ
import { TestInstantiationService } from '../../../../../../platform/instantiation/test/common/instantiationServiceMock.js';
import { IOutputService } from '../../../../../services/output/common/output.js';
import { IWorkspaceContextService } from '../../../../../../platform/workspace/common/workspace.js';
import { AgentHostContribution, AgentHostSessionListController, AgentHostSessionHandler, getAgentHostBranchNameHint } from '../../../browser/agentSessions/agentHost/agentHostChatContribution.js';
import { AgentHostContribution, AgentHostSessionListController, AgentHostSessionHandler } from '../../../browser/agentSessions/agentHost/agentHostChatContribution.js';
import { AgentHostLanguageModelProvider } from '../../../browser/agentSessions/agentHost/agentHostLanguageModelProvider.js';
import { IFileService } from '../../../../../../platform/files/common/files.js';
import { TestFileService } from '../../../../../test/common/workbenchTestServices.js';
Expand All @@ -53,7 +53,6 @@ import { IAgentHostTerminalService } from '../../../../terminal/browser/agentHos
import { IAgentHostSessionWorkingDirectoryResolver } from '../../../browser/agentSessions/agentHost/agentHostSessionWorkingDirectoryResolver.js';
import { ILanguageModelToolsService } from '../../../common/tools/languageModelToolsService.js';
import { IPromptsService } from '../../../common/promptSyntax/service/promptsService.js';
import { SessionConfigKey } from '../../../../../../platform/agentHost/common/sessionConfigKeys.js';
import { IChatWidgetService } from '../../../browser/chat.js';
import { ChatQuestionCarouselData } from '../../../common/model/chatProgressTypes/chatQuestionCarouselData.js';

Expand Down Expand Up @@ -2659,20 +2658,46 @@ suite('AgentHostChatContribution', () => {
await turnPromise;

assert.strictEqual(agentHostService.createSessionCalls.length, 1);
assert.deepStrictEqual(agentHostService.createSessionCalls[0].config, { ...config, [SessionConfigKey.BranchNameHint]: 'add-agent-host-session-configuration-flow' });
}));

test('handler derives deterministic branch name hints from first request text', () => {
assert.deepStrictEqual([
getAgentHostBranchNameHint('Add Agent Host session configuration flow'),
getAgentHostBranchNameHint(' Fix: worktree picker + branch config! '),
getAgentHostBranchNameHint('---'),
], [
'add-agent-host-session-configuration-flow',
'fix-worktree-picker-branch-config',
undefined,
]);
});
assert.deepStrictEqual(agentHostService.createSessionCalls[0].config, config);
}));

test('handler forwards request session config via SessionConfigChanged on eager-create path', () => runWithFakedTimers({ useFakeTimers: true }, async () => {
const { sessionHandler, agentHostService, chatAgentService } = createContribution(disposables);

// Pre-seed an eagerly-created backend session so the handler
// hits the eager-create branch in `_invokeAgent` (the one that
// dispatches `SessionConfigChanged` instead of calling
// `createSession` with the config inline).
const sessionUri = AgentSession.uri('copilot', 'eager-config');
agentHostService.sessionStates.set(sessionUri.toString(), {
...createSessionState({ resource: sessionUri.toString(), provider: 'copilot', title: 'Test', status: SessionStatus.Idle, createdAt: Date.now(), modifiedAt: Date.now() }),
lifecycle: SessionLifecycle.Ready,
turns: [],
});

const sessionResource = URI.from({ scheme: 'agent-host-copilot', path: '/eager-config' });
const chatSession = await sessionHandler.provideChatSessionContent(sessionResource, CancellationToken.None);
disposables.add(toDisposable(() => chatSession.dispose()));

agentHostService.dispatchedActions.length = 0;

const registered = chatAgentService.registeredAgents.get('agent-host-copilot')!;
const config = { isolation: 'worktree', branch: 'main' };
const turnPromise = registered.impl.invoke(
makeRequest({ message: 'Fix worktree branch hint propagation', sessionResource, agentHostSessionConfig: config }),
() => { }, [], CancellationToken.None,
);
await timeout(10);
const turnDispatch = agentHostService.turnActions[0];
const turnAction = turnDispatch.action as ITurnStartedAction;
agentHostService.fireAction({ action: turnDispatch.action, serverSeq: 1, origin: { clientId: agentHostService.clientId, clientSeq: turnDispatch.clientSeq } });
agentHostService.fireAction({ action: { type: 'session/turnComplete', session: turnAction.session, turnId: turnAction.turnId } as SessionAction, serverSeq: 2, origin: undefined });
await turnPromise;

const configChanged = agentHostService.dispatchedActions.find(d => d.action.type === ActionType.SessionConfigChanged);
assert.ok(configChanged, 'expected a SessionConfigChanged dispatch');
assert.deepStrictEqual((configChanged!.action as { config: Record<string, unknown> }).config, config);
}));

test('handler uses registered working directory resolver', () => runWithFakedTimers({ useFakeTimers: true }, async () => {
const resolvedWorkingDirectory = URI.file('/resolved/working/dir');
Expand Down
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