Fix split button missing rounded corners when rendered as single action (#8610)

* Initial plan

* Initial plan for fixing button missing rounded corners

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>
Agent-Logs-Url: https://github.com/microsoft/vscode-pull-request-github/sessions/bf4729e0-f0d3-4c05-88a6-cf04d33863be

* Fix button missing rounded corners when hasSingleAction is true

Add CSS rule for button.split-left:only-child to restore full
border-radius and border-right when the split-left button is the
only child in the container (i.e., when split/split-right elements
are not rendered because hasSingleAction is true).

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>
Agent-Logs-Url: https://github.com/microsoft/vscode-pull-request-github/sessions/bf4729e0-f0d3-4c05-88a6-cf04d33863be

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/@types/vscode.proposed.chatParticipantPrivate.d.ts

@@ -50,6 +50,12 @@ declare module 'vscode' {
 		constructor(cell: TextDocument);
 	}
 
+	export interface ChatRequestSessionGrouping {
+		readonly id: string;
+		readonly order: number;
+		readonly kind?: string;
+	}
+
 	export interface ChatRequest {
 		/**
 		 * The id of the chat request. Used to identity an interaction with any of the chat surfaces.
@@ -116,6 +122,11 @@ declare module 'vscode' {
 		 */
 		readonly parentRequestId?: string;
 
+		/**
+		 * Optional metadata used to group related requests together in the UI.
+		 */
+		readonly sessionGrouping?: ChatRequestSessionGrouping;
+
 		/**
 		 * The permission level for tool auto-approval in this request.
 		 * - `'autoApprove'`: Auto-approve all tool calls and retry on errors.

src/@types/vscode.proposed.chatSessionsProvider.d.ts

@@ -100,7 +100,7 @@ declare module 'vscode' {
 			readonly command?: string;
 		};
 
-		readonly sessionOptions: ReadonlyArray<{ optionId: string; value: ChatSessionProviderOptionItem }>;
+		readonly sessionOptions: ReadonlyArray<{ optionId: string; value: string | ChatSessionProviderOptionItem }>;
 	}
 
 	/**
@@ -116,7 +116,7 @@ declare module 'vscode' {
 	 *
 	 * @param sessionResource The resource of the chat session being forked.
 	 * @param request The request turn that marks the fork point. The forked session includes all turns
-	 * upto this request turn and includes this request turn itself. If undefined, fork the full session.
+	 * upto this request turn and excludes this request turn itself. If undefined, fork the full session.
 	 * @param token A cancellation token.
 	 * @returns The forked session item.
 	 */
@@ -396,9 +396,12 @@ declare module 'vscode' {
 		/**
 		 * Options configured for this session as key-value pairs.
 		 * Keys correspond to option group IDs (e.g., 'models', 'subagents').
+		 * Values can be either:
+		 * - A string (the option item ID) for backwards compatibility
+		 * - A ChatSessionProviderOptionItem object to include metadata like locked state
 		 * TODO: Strongly type the keys
 		 */
-		readonly options?: Record<string, ChatSessionProviderOptionItem>;
+		readonly options?: Record<string, string | ChatSessionProviderOptionItem>;
 
 		/**
 		 * Callback invoked by the editor for a currently running response. This allows the session to push items for the
@@ -429,7 +432,7 @@ declare module 'vscode' {
 		 *
 		 * @param sessionResource The resource of the chat session being forked.
 		 * @param request The request turn that marks the fork point. The forked session includes all turns
-		 * until this request turn and includes this request turn itself. If undefined, fork the full session.
+		 * upto this request turn and excludes this request turn itself. If undefined, fork the full session.
 		 * @param token A cancellation token.
 		 * @returns The forked session item.
 		 */
@@ -456,7 +459,7 @@ declare module 'vscode' {
 			/**
 			 * The new value assigned to the option. When `undefined`, the option is cleared.
 			 */
-			readonly value: ChatSessionProviderOptionItem;
+			readonly value: string | ChatSessionProviderOptionItem;
 		}>;
 	}
 
@@ -489,7 +492,7 @@ declare module 'vscode' {
 		 * @return The {@link ChatSession chat session} associated with the given URI.
 		 */
 		provideChatSessionContent(resource: Uri, token: CancellationToken, context: {
-			readonly sessionOptions: ReadonlyArray<{ optionId: string; value: ChatSessionProviderOptionItem }>;
+			readonly sessionOptions: ReadonlyArray<{ optionId: string; value: string | ChatSessionProviderOptionItem }>;
 		}): Thenable<ChatSession> | ChatSession;
 
 		/**
@@ -514,7 +517,7 @@ declare module 'vscode' {
 		/**
 		 * The new value assigned to the option. When `undefined`, the option is cleared.
 		 */
-		readonly value: ChatSessionProviderOptionItem | undefined;
+		readonly value: string | undefined;
 	}
 
 	export namespace chat {
@@ -544,7 +547,7 @@ declare module 'vscode' {
 		 * The initial option selections for the session, provided with the first request.
 		 * Contains the options the user selected (or defaults) before the session was created.
 		 */
-		readonly initialSessionOptions?: ReadonlyArray<{ optionId: string; value: ChatSessionProviderOptionItem }>;
+		readonly initialSessionOptions?: ReadonlyArray<{ optionId: string; value: string | ChatSessionProviderOptionItem }>;
 	}
 
 	export interface ChatSessionCapabilities {
@@ -667,6 +670,6 @@ declare module 'vscode' {
 		 *
 		 * Keys correspond to option group IDs (e.g., 'models', 'subagents').
 		 */
-		readonly newSessionOptions?: Record<string, ChatSessionProviderOptionItem>;
+		readonly newSessionOptions?: Record<string, string | ChatSessionProviderOptionItem>;
 	}
 }

webviews/common/common.css

@@ -430,6 +430,11 @@ button.split-left {
 	border-right: none;
 }
 
+button.split-left:only-child {
+	border-radius: 4px;
+	border-right: 1px solid var(--vscode-button-border, transparent);
+}
+
 .split {
 	background-color: var(--vscode-button-background);
 	border-top: 1px solid var(--vscode-button-border);