sessions: set session title to first message text immediately

[roblourens]

When a new agent host session starts, the title shows "New Session" for a long time until the AI-generated title arrives. This fixes the issue by immediately setting the title to the user's first message text.

Changes

1. agentSideEffects.ts — On the first turn (SessionTurnStarted with turns.length === 0), immediately dispatch SessionTitleChanged with the user's message text so the state manager has a meaningful title right away. Guards against clobbering user-renamed titles or whitespace-only messages.

2. agentService.ts — listSessions() now overlays the title from the state manager's live state (not just status/model). This prevents the stale SDK-reported title from overwriting the immediate title that was already dispatched. Uses DEFAULT_SESSION_TITLE constant to avoid hardcoding the placeholder string.

3. common/agentService.ts — Extracted DEFAULT_SESSION_TITLE constant for the initial placeholder title, used consistently in session creation and side effects checks.

(Written by Copilot)

[github-actions]

Screenshot Changes

Base: d75a4078 Current: 6314404e

Changed (2)

agentSessionsViewer/CloudProvider/Dark

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agentSessionsViewer/CloudProvider/Light

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blocks-ci screenshots changed

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#### editor/codeEditor/CodeEditor/Dark
![screenshot](https://hediet-screenshots.azurewebsites.net/images/cb32a3e854b5734fe5aaca2318f2e0a42ee821b05ea97883ea42c5ba95edb3c3)

#### editor/codeEditor/CodeEditor/Light
![screenshot](https://hediet-screenshots.azurewebsites.net/images/42624fbba5e0db7f32c224b5eb9c5dd3b08245697ae2e7d2a88be0d7c287129b)

[Copilot]

Pull request overview

Improves the Agents/Sessions UI experience by ensuring new sessions get a meaningful title immediately (using the user’s first message), and by ensuring session listings reflect the state manager’s live title instead of being overwritten by stale provider/SDK metadata.

Changes:

• Dispatch SessionTitleChanged on the first SessionTurnStarted to set the title from the first user message.
• Update AgentService.listSessions() to overlay the live state manager title into returned session metadata.
• Consume notify/sessionSummaryChanged notifications in local/remote sessions providers to react to title changes via the notification channel.

Show a summary per file

File	Description
src/vs/sessions/contrib/remoteAgentHost/browser/remoteAgentHostSessionsProvider.ts	Handles notify/sessionSummaryChanged (title) to update cached session titles.
src/vs/sessions/contrib/localAgentHost/browser/localAgentHostSessionsProvider.ts	Handles notify/sessionSummaryChanged (title) to update cached session titles.
src/vs/platform/agentHost/node/agentSideEffects.ts	Sets session title to first user message text on the first turn.
src/vs/platform/agentHost/node/agentService.ts	Overlays live state manager title into listSessions() results.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/platform/agentHost/node/agentSideEffects.ts:568

• This new behavior (auto-setting the session title on the first turn) isn’t covered by existing AgentSideEffects tests. Please add a unit test that asserts a SessionTitleChanged server action is emitted on the first SessionTurnStarted for a new session, and that it does not trigger when the title was already customized (e.g. via SessionTitleChanged).

				// On the very first turn, immediately set the session title to the
				// user's message so the UI shows a meaningful title right away
				// instead of "New Session" while waiting for the AI-generated title.
				const state = this._stateManager.getSessionState(action.session);
				if (state && state.turns.length === 0) {
					this._stateManager.dispatchServerAction({
						type: ActionType.SessionTitleChanged,
						session: action.session,
						title: action.userMessage.text,
					});

• Files reviewed: 4/4 changed files
• Comments generated: 4

[Copilot]

Pull request overview

Improves session UX in the Agent Host by ensuring new sessions get a meaningful title immediately (using the first user message) and by preventing listSessions() results from overwriting that live title with stale provider/SDK titles.

Changes:

• Dispatch session/titleChanged on the first session/turnStarted to immediately set the title from the user’s message text.
• Update AgentService.listSessions() to overlay live state manager title (when non-empty) over provider/SDK session summaries.
• Adjust and add tests to validate immediate title behavior and listSessions() title overlay.

Show a summary per file

File	Description
src/vs/platform/agentHost/node/agentSideEffects.ts	Adds first-turn fallback title dispatch based on the user’s first message.
src/vs/platform/agentHost/node/agentService.ts	Overlays live state-manager title into listSessions() results; initializes new session title as empty string.
src/vs/platform/agentHost/test/node/protocol/sessionFeatures.integrationTest.ts	Updates existing title broadcast test to account for fallback-first behavior; adds integration test for immediate title + listSessions().
src/vs/platform/agentHost/test/node/agentSideEffects.test.ts	Adds unit coverage for first-turn immediate title behavior, including whitespace and second-turn cases.
src/vs/platform/agentHost/test/node/agentService.test.ts	Adds unit test ensuring listSessions() prefers live state-manager title over SDK summary.
src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts	Updates mock session creation to start with an empty title.

Copilot's findings

• Files reviewed: 6/6 changed files
• Comments generated: 2

[Copilot]

Pull request overview

This PR improves the user experience for newly created agent host sessions by setting a meaningful session title immediately (based on the first user message) instead of showing a placeholder until an agent-generated title arrives. It does this by updating server-side side effects to emit an early session/titleChanged, and by ensuring listSessions() prefers the state manager’s live title so refreshed session lists don’t regress to stale provider/SDK titles.

Changes:

• Dispatch an immediate session/titleChanged on the first session/turnStarted, using the trimmed first user message as a fallback title.
• Update AgentService.listSessions() to overlay the live state-manager title (in addition to status/model) onto provider listSessions() results.
• Update/extend agent host protocol and unit/integration tests to cover the immediate-title behavior and the listSessions() overlay.

Show a summary per file

File	Description
src/vs/platform/agentHost/node/agentSideEffects.ts	Emits a fallback title change on the first user turn when the title is still unset.
src/vs/platform/agentHost/node/agentService.ts	Overlays the live state-manager title into listSessions() results; initializes new session title as empty.
src/vs/platform/agentHost/test/node/protocol/sessionFeatures.integrationTest.ts	Adds coverage for immediate title behavior and adjusts existing title broadcast test.
src/vs/platform/agentHost/test/node/agentSideEffects.test.ts	Adds unit tests for first-turn immediate title dispatch and guard conditions.
src/vs/platform/agentHost/test/node/agentService.test.ts	Adds test verifying listSessions() prefers state-manager title over SDK/provider title.
src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts	Updates mock session creation to align with empty initial title behavior.

Copilot's findings

• Files reviewed: 6/6 changed files
• Comments generated: 2

[Copilot]

Pull request overview

This PR improves early session UX in the agent host by setting a meaningful session title immediately on the first user turn (using the first message text), and ensuring subsequent listSessions() results don’t overwrite that early title with the provider’s placeholder value.

Changes:

• Dispatch session/titleChanged on the first session/turnStarted when the session is still using the default placeholder title.
• Update AgentService.listSessions() to prefer the live state-manager title (when not the placeholder) over the provider/SDK-reported title.
• Introduce and reuse a shared DEFAULT_SESSION_TITLE constant and add tests covering the new behavior.

Show a summary per file

File	Description
src/vs/platform/agentHost/common/agentService.ts	Introduces DEFAULT_SESSION_TITLE constant for consistent placeholder title usage.
src/vs/platform/agentHost/node/agentSideEffects.ts	On first turn, dispatches an immediate SessionTitleChanged based on the user’s message text.
src/vs/platform/agentHost/node/agentService.ts	Overlays the live state-manager title in listSessions() to avoid stale/placeholder clobbering.
src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts	Uses DEFAULT_SESSION_TITLE in test session creation to match production behavior.
src/vs/platform/agentHost/test/node/protocol/sessionFeatures.integrationTest.ts	Updates title broadcast test expectations and adds coverage for the immediate first-turn title + listSessions.
src/vs/platform/agentHost/test/node/agentSideEffects.test.ts	Adds unit coverage for immediate title dispatch and guard conditions.
src/vs/platform/agentHost/test/node/agentService.test.ts	Adds unit coverage for listSessions() title overlay behavior.

Copilot's findings

• Files reviewed: 7/7 changed files
• Comments generated: 1