sessions: simplify titlebar session actions

src/vs/sessions/LAYOUT.md

@@ -84,6 +84,8 @@ The Agent Sessions titlebar includes a command center with a custom title bar wi
 The widget:
 - Extends `BaseActionViewItem` and renders a clickable label showing the active session title
 - Shows kind icon (provider type icon), session title, repository folder name, and the active git branch/worktree name in parentheses when available, plus the changes summary (+insertions -deletions)
+- Uses spacing between titlebar groups instead of vertical separator bars, and shows the session title metadata without the previous dot separator before the folder/worktree label
+- Keeps the command center focused on the session picker widget itself, without an adjacent "Mark as Done" action button
 - Truncates the repository/worktree metadata with ellipsis before truncating the primary AI-generated session title when command center space is constrained
 - On click, opens the `AgentSessionsPicker` quick pick to switch between sessions
 - Gets the active session label from `IActiveSessionService.getActiveSession()` and the live model title from `IChatService`, falling back to "New Session" if no active session is found
@@ -665,6 +667,9 @@ interface IPartVisibilityState {
 | 2026-04-22 | Added a sessions-workbench notification offset override so the shared notification controllers no longer push top-right notifications down to `42px`; sessions now reapply a fixed `40px` top offset for top-right notification center/toast placement. |
 | 2026-04-22 | Generalized the auxiliary bar snap-close prevention to trigger whenever the main editor part is visible (any editor type), so the behavior now applies automatically without maintaining an editor-type allowlist. |
 | 2026-04-22 | Updated the sessions auxiliary bar sizing rules so attached diff editors and integrated browser editors keep the normal 270px auxiliary-bar minimum width while disabling sash snap-to-close in that state, and the titlebar toggle continues to hide/show the secondary sidebar normally. |
+| 2026-04-21 | Renamed the command-center "Add Chat" titlebar action to "New Sub-Session" so the plus-button tooltip matches the sub-session workflow. |
+| 2026-04-21 | Removed the remaining left-margin spacing after the titlebar's VS Code and session-picker items, and dropped the command-center "Mark as Done" checkmark button next to the active session title. |
+| 2026-04-21 | Removed the titlebar's vertical separator bars in favor of spacing-only group separation, and removed the dot separator between the active session title and its folder/worktree metadata. |
 | 2026-04-21 | Updated the sessions chat composite bar tabs to preserve each chat title's original casing instead of applying per-word capitalization. |
 | 2026-04-21 | Moved the sessions-only default notification placement to bottom-right and documented the sessions-specific notification center offsets: `15px` from the bottom/right or bottom/left edges, and `top: 40px; right: 15px;` for top-right placement. |
 | 2026-04-17 | Added a subtle 1px titlebar-token border around the sessions account widget's GitHub profile image, including the inactive-window variant, and documented the avatar chrome in the layout spec. |

src/vs/sessions/browser/parts/media/titlebarpart.css

@@ -63,13 +63,9 @@
 	align-items: center;
 }
 
-/* Separator before right layout toolbar (only when session actions toolbar also has actions) */
-.monaco-workbench .part.titlebar > .sessions-titlebar-container > .titlebar-right > .titlebar-session-actions-container:not(.has-no-actions) + .titlebar-right-layout-container:not(.has-no-actions)::before {
-	content: '';
-	width: 1px;
-	height: 16px;
-	margin: 0 8px;
-	background-color: var(--vscode-disabledForeground);
+/* Add spacing between the session action group and the right layout actions. */
+.monaco-workbench .part.titlebar > .sessions-titlebar-container > .titlebar-right > .titlebar-session-actions-container:not(.has-no-actions) + .titlebar-right-layout-container:not(.has-no-actions) {
+	margin-left: 8px;
 }
 
 /* Toggled action buttons in session actions toolbar */

src/vs/sessions/contrib/changes/browser/media/changesTitleBarWidget.css

@@ -5,19 +5,8 @@
 
 /* ---- Changes titlebar action spacing ---- */
 
-/* Separator between local-session actions (Run, VS Code) and fixed toggles (Terminal, Changes).
+/* Remove leftover spacing between local-session actions (Run, VS Code) and fixed toggles (Terminal, Changes).
  * Targets the action following the VS Code icon (any Codicon.vscode variant). */
 .agent-sessions-workbench .titlebar-session-actions-container .monaco-action-bar .actions-container > .action-item:has(.codicon[class*="codicon-vscode"]) + .action-item {
-	position: relative;
-	margin-left: 17px;
-}
-
-.agent-sessions-workbench .titlebar-session-actions-container .monaco-action-bar .actions-container > .action-item:has(.codicon[class*="codicon-vscode"]) + .action-item::before {
-	content: '';
-	position: absolute;
-	left: -9px;
-	top: 3px;
-	width: 1px;
-	height: 16px;
-	background-color: var(--vscode-disabledForeground);
+	margin-left: 0;
 }

src/vs/sessions/contrib/sessions/browser/media/sessionsTitleBarWidget.css

@@ -10,21 +10,7 @@
 }
 
 .agent-sessions-workbench .command-center .monaco-action-bar .actions-container > .action-item.agent-sessions-titlebar-container + .action-item {
-	position: relative;
-	margin-left: 8px;
-	padding-left: 12px;
-}
-
-.agent-sessions-workbench .command-center .monaco-action-bar .actions-container > .action-item.agent-sessions-titlebar-container + .action-item::before {
-	content: '';
-	position: absolute;
-	left: 0;
-	top: 50%;
-	width: 1px;
-	height: 16px;
-	transform: translateY(-50%);
-	background-color: var(--vscode-commandCenter-border);
-	pointer-events: none;
+	margin-left: 0;
 }
 
 .command-center .agent-sessions-titlebar-container {
@@ -121,12 +107,6 @@
 	opacity: 0.7;
 }
 
-/* Dot separator */
-.command-center .agent-sessions-titlebar-container .agent-sessions-titlebar-separator {
-	opacity: 0.5;
-	flex-shrink: 0;
-}
-
 /* Provider label (shown for untitled sessions) */
 .command-center .agent-sessions-titlebar-container .agent-sessions-titlebar-provider {
 	display: flex;

src/vs/sessions/contrib/sessions/browser/sessionsTitleBarWidget.ts

@@ -131,7 +131,7 @@ export class SessionsTitleBarWidget extends BaseActionViewItem {
 			const icon = this._getActiveSessionIcon();
 			const repoLabel = this._getRepositoryLabel();
 			const repoDetailLabel = this._getRepositoryDetailLabel();
-			const pillLabel = repoLabel ? `${label} \u00B7 ${repoLabel}${repoDetailLabel ? ` (${repoDetailLabel})` : ''}` : label;
+			const pillLabel = repoLabel ? `${label} ${repoLabel}${repoDetailLabel ? ` (${repoDetailLabel})` : ''}` : label;
 			// Build a render-state key from all displayed data
 			const renderState = `${icon?.id ?? ''}|${label}|${repoLabel ?? ''}|${repoDetailLabel ?? ''}`;
 
@@ -171,11 +171,6 @@ export class SessionsTitleBarWidget extends BaseActionViewItem {
 			if (repoLabel) {
 				const detailsEl = $('span.agent-sessions-titlebar-details');
 
-				const separator1 = $('span.agent-sessions-titlebar-separator');
-				separator1.textContent = '\u00B7';
-				separator1.setAttribute('aria-hidden', 'true');
-				detailsEl.appendChild(separator1);
-
 				const repoEl = $('span.agent-sessions-titlebar-repo');
 				repoEl.textContent = repoDetailLabel ? `${repoLabel} (${repoDetailLabel})` : repoLabel;
 				detailsEl.appendChild(repoEl);

src/vs/sessions/contrib/sessions/browser/views/sessionsViewActions.ts

@@ -701,16 +701,6 @@ registerAction2(class MarkSessionAsDoneAction extends Action2 {
 			icon: Codicon.check,
 			precondition: ChatContextKeys.requestInProgress.negate(),
 			menu: [{
-				id: Menus.CommandCenter,
-				order: 103,
-				when: ContextKeyExpr.and(
-					IsAuxiliaryWindowContext.negate(),
-					SessionsWelcomeVisibleContext.negate(),
-					IsNewChatSessionContext.negate(),
-					IsActiveSessionArchivedContext.negate()
-				)
-			},
-			{
 				id: MenuId.ChatEditingSessionChangesToolbar,
 				group: 'navigation',
 				order: 1,
@@ -750,7 +740,7 @@ registerAction2(class AddChatAction extends Action2 {
 	constructor() {
 		super({
 			id: 'agentSession.addChat',
-			title: localize2('addChat', "Add Chat"),
+			title: localize2('addChat', "New Sub-Session"),
 			icon: Codicon.plus,
 			menu: [{
 				id: Menus.CommandCenter,