Apply session _meta once per adapter update and keep it transactional

.github/skills/sessions/SKILL.md

@@ -80,9 +80,9 @@ Then read the relevant spec for the area you are changing (see table below). If
 - **`/btw` must bypass queue/steer, may anchor to `activeTurn`, and should activate the new peer chat through the normal sessions API**: mark the silent slash command `executeDuringRequest` so the chat widget invokes it independently, validate its anchor against completed turns or the current active turn, and after creating the side chat activate it via `ISessionsService.openChat(...)` before sending on that chat. Provider side-chat creation must lock on the new chat, not the source send key. Wrap the first provider prompt with a succinct instruction to prefer explanation over action and avoid work unless explicitly requested; include bounded user-visible active-turn markdown when native forks omit it, then strip the private wrapper from reconstructed visible history. Never inject reasoning or tool payloads.
 - **A responsive-layout autorun must re-baseline (not react) to controller-driven restores, holding the flag across the async reveal**: the desktop [D7] responsive sidebar hides the sessions sidebar when small + editor + aux-bar are all open. Switching sessions restores layout via two async paths — the desktop aux-bar restore (`openView`/`openViewContainer`) **and** the base controller's editor working-set apply (`_applyWorkingSet`, which reveals the editor part *after* an `await` and runs on a `Sequencer` microtask). Both reveal parts in a *later* autorun run, so an inline "same-run session changed" check only absorbs the synchronous transition and the async reveal still auto-hid the sidebar on navigation. Fix: a shared base-controller `_withSessionLayoutRestore(work)` epoch wraps **both** restore paths (the working-set wrap is the critical one for non-modal editors); the D7 autorun re-baselines `_previousSpaceConstrained` while `_isRestoringSessionLayout` is true. Also gate the constrained derivation on `!multipleSessionsVisibleObs` so the feature is disabled with multiple sessions visible. Never use a `setTimeout` to bridge the async reveal — tie the flag to the actual promise.
 - **A promise-tied "epoch" helper must decrement synchronously for void/sync work, only deferring for real Promises**: `_withSessionLayoutRestore` increments a depth counter, runs `work()`, and decrements when done. If it *always* schedules the decrement on a microtask (`Promise.resolve(result).finally(...)`) — even when `work()` returns `undefined` (the common no-op restore, e.g. a session with no workspace) — the depth stays elevated for the entire synchronous caller/test body, so `_isRestoringSessionLayout` reads `true` forever and the consumer (D7) silently stops acting. Only defer the decrement when `work()` returns a thenable; for void/sync (or throwing) work, decrement in the `finally`.
-- **A quick-chat's workspace-less kind is seeded at adapter construction and only ever promoted — every path that can carry `_meta` must carry it**: `AgentHostSessionAdapter` seeds its session-kind (`QuickChatSessionKind` vs `WorkspaceSessionKind`) from `readSessionWorkspaceless(metadata._meta)` in the constructor, and `_promoteToQuickChatIfWorkspaceless` (from `update()`/`setMeta()`) later flips it to a quick chat the first time an authoritative `_meta` says workspace-less — never back, since an absent marker means "not included", not "cleared". So the `_meta.workspaceless` tag must ride on **every** metadata path: `_refreshSessions()`/`listSessions`, the live `_handleSessionAdded(summary)` notification, **and both ends of the AHP `root/listSessions` round-trip** (`protocolServerHandler.ts` and `remoteAgentHostProtocolClient.ts` build their wire items field-by-field, and `satisfies SessionSummary` does **not** catch a dropped *optional* field — this is exactly how the bug shipped twice). Dropping it makes a committed quick chat render under a section header labelled with its raw session UUID, leaking `<userHome>/.copilot/chats/<id>` as a `workspace` (breaking the archive-on-delete fallback, list badges, changes/files) until a later `_meta` heals it. `_persistCache` must overlay the adapter's **live** `isQuickChat` rather than the `_metaByRawId` snapshot, or the next `updateAdapter` silently strips the marker from the startup cache. On the host, `AgentService.listSessions()` overlays `_meta.workspaceless` onto the provider listing from the persisted `copilot.workspaceless` session metadata (the providers themselves, e.g. `CopilotAgent.listSessions()`, do not emit it) so restored sessions carry the tag once the state-manager live summary is gone. The host still keeps the tag on both the summary `_meta` and `SessionState._meta` (`createSessionState(summary)` copies it) so the channels stay consistent. **Note the provider tests cannot catch a wire-level drop** — `MockAgentHostService.listSessions` returns stored `IAgentSessionMetadata` verbatim, bypassing both mappers — so wire regressions need tests at the protocol layer.
+- **A quick-chat's workspace-less kind is seeded at adapter construction and only ever promoted — every path that can carry `_meta` must carry it**: `AgentHostSessionAdapter` seeds its session-kind (`QuickChatSessionKind` vs `WorkspaceSessionKind`) from `readSessionWorkspaceless(metadata._meta)` in the constructor, and `_promoteToQuickChatIfWorkspaceless` (from `update()`/`setMeta()`) later flips it to a quick chat the first time an authoritative `_meta` says workspace-less — never back, since an absent marker means "not included", not "cleared". So the `_meta.workspaceless` tag must ride on **every** metadata path: `_refreshSessions()`/`listSessions`, the live `_handleSessionAdded(summary)` notification, **and both ends of the AHP `root/listSessions` round-trip** (`protocolServerHandler.ts` and `remoteAgentHostProtocolClient.ts` build their wire items field-by-field, and `satisfies SessionSummary` does **not** catch a dropped *optional* field — this is exactly how the bug shipped twice). Dropping it makes a committed quick chat render under a section header labelled with its raw session UUID, leaking `<userHome>/.copilot/chats/<id>` as a `workspace` (breaking the archive-on-delete fallback, list badges, changes/files) until a later `_meta` heals it. `_persistCache` must overlay the adapter's **live** `isQuickChat` rather than the `_metaByRawId` snapshot, or the next `updateAdapter` silently strips the marker from the startup cache. On the host, `AgentService.listSessions()` overlays `_meta.workspaceless` onto the provider listing from the persisted `agentHost.workspaceless` session-database key (`AH_META_WORKSPACELESS_DB_KEY`) (the providers themselves, e.g. `CopilotAgent.listSessions()`, do not emit it) so restored sessions carry the tag once the state-manager live summary is gone. The host still keeps the tag on both the summary `_meta` and `SessionState._meta` (`createSessionState(summary)` copies it) so the channels stay consistent. **Note the provider tests cannot catch a wire-level drop** — `MockAgentHostService.listSessions` returns stored `IAgentSessionMetadata` verbatim, bypassing both mappers — so wire regressions need tests at the protocol layer.
 - **Don't infer "quick chat" from `workspace === undefined`**: a session's workspace observable is `undefined` for genuine quick chats but also transiently/edge-case for workspace-bound sessions, so keying quick-chat UI (context keys, list grouping) on it is imprecise. Expose the intent explicitly via the optional `ISession.isQuickChat: IObservable<boolean>` (only quick-chat-capable providers set it; absent ⇒ `false`). The agent-host adapter exposes it as a monotonic observable seeded from `readSessionWorkspaceless(metadata._meta)` at construction and promoted by later authoritative `_meta`; non-quick-chat providers omit it. Consume it through `isQuickChatSession(session)` / `session.isQuickChat?.read(reader) ?? false`.
-- **Workspace-less is inferred from absent `workingDirectory` — exclude forks from that inference**: in `CopilotAgent.createSession`, `isWorkspaceless` must be `!sessionConfig.fork && !sessionConfig.workingDirectory`. A fork that arrives without an explicit `workingDirectory` should inherit the source session's context, not be tagged `copilot.workspaceless` and dropped into a scratch dir + quick-chat system prompt.
+- **Workspace-less is inferred from absent `workingDirectory` — exclude forks from that inference**: in `CopilotAgent.createSession`, `isWorkspaceless` must be `!sessionConfig.fork && !sessionConfig.workingDirectory`. A fork that arrives without an explicit `workingDirectory` should inherit the source session's context, not be tagged `agentHost.workspaceless` and dropped into a scratch dir + quick-chat system prompt.
 - **On a failed quick-chat create, don't activate an unrelated draft**: `SessionsService.openQuickChat` must, on `createQuickChat` throwing, log and return `undefined` without falling back to `_activate(newSession.get())` — that observable can hold a workspace-bound draft from a different call site, so activating it is surprising. Return the activated `IActiveSession` from `_activate`/`openQuickChat` (setActive is synchronous and yields the wrapper) and have the caller focus that exact value, rather than re-reading `activeSession.get()` afterwards.
 - **Hide an aux-bar view CONTAINER via `hideIfEmpty: true` + a view `when`, not a container `when`**: `IViewContainerDescriptor` has **no `when`** property (only `IViewDescriptor` does). To conditionally hide a whole container (its tab/title) — e.g. the Agents-window Changes/Files containers for workspace-less sessions — put the context-key `when` on the inner view(s) and set `hideIfEmpty: true` on the container. Container visibility is `hideIfEmpty && activeViewDescriptors.length === 0` (`viewsService.updateViewContainerEnablementContextKey`), and `activeViewDescriptors` already respects each view's `when`, so the container hides reactively when all its views' `when` go false.
 - **Don't gate "is this a quick chat?" routing on `isCreated && isQuickChat`**: a quick-chat **draft** is `Untitled`, so `isCreated` (`= status !== Untitled`, `visibleSessions.ts`) is `false` — yet it is still a quick chat. Gating quick-chat routing on `isCreated && isQuickChat` (e.g. the "New" action) makes a draft fall through to the workspace path (scratch-dir composer, no session-type picker, "No models available"). Route on **`isQuickChat` alone** so drafts and committed quick chats behave identically; use `isCreated` only when you genuinely need to distinguish a committed session from an in-composer draft.

src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts

@@ -765,6 +765,29 @@ suite('ProtocolServerHandler', () => {
 		assert.deepStrictEqual(result.items.map(item => readSessionWorkspaceless(item._meta)), [true]);
 	});
 
+	test('listSessions omits _meta when the agent provides none', async () => {
+		// The wire item is built field by field and `satisfies SessionSummary`
+		// cannot catch a dropped optional, so pin the absent case too: a
+		// listing must not start manufacturing an empty `_meta` bag that later
+		// overwrites a richer one on the client.
+		agentService.listedSessions.push({
+			session: URI.parse(sessionUri),
+			startTime: 1000,
+			modifiedTime: 2000,
+			summary: 'Session Summary',
+		});
+
+		const transport = connectClient('client-list-no-meta');
+		transport.sent.length = 0;
+		const responsePromise = waitForResponse(transport, 2);
+
+		transport.simulateMessage(request(2, 'listSessions'));
+		const resp = await responsePromise;
+
+		const result = (resp as unknown as { result: ListSessionsResult }).result;
+		assert.deepStrictEqual(result.items.map(item => item._meta), [undefined]);
+	});
+
 	test('createSession returns null and broadcasts project in sessionAdded summary', async () => {
 		const transport = connectClient('client-create');
 		transport.sent.length = 0;