fix(coding-agent): split /clone from /fork UX

closes #2962

packages/coding-agent/src/modes/rpc/rpc-client.ts

@@ -342,6 +342,15 @@ export class RpcClient {
 		return this.getData(response);
 	}
 
+	/**
+	 * Clone the current active branch into a new session.
+	 * @returns Object with `cancelled: true` if an extension cancelled the clone
+	 */
+	async clone(): Promise<{ cancelled: boolean }> {
+		const response = await this.send({ type: "clone" });
+		return this.getData(response);
+	}
+
 	/**
 	 * Get messages available for forking.
 	 */

packages/coding-agent/src/modes/rpc/rpc-mode.ts

@@ -567,6 +567,18 @@ export async function runRpcMode(runtimeHost: AgentSessionRuntime): Promise<neve
 				return success(id, "fork", { text: result.selectedText, cancelled: result.cancelled });
 			}
 
+			case "clone": {
+				const leafId = session.sessionManager.getLeafId();
+				if (!leafId) {
+					return error(id, "clone", "Cannot clone session: no current entry selected");
+				}
+				const result = await runtimeHost.fork(leafId, { position: "at" });
+				if (!result.cancelled) {
+					await rebindSession();
+				}
+				return success(id, "clone", { cancelled: result.cancelled });
+			}
+
 			case "get_fork_messages": {
 				const messages = session.getUserMessagesForForking();
 				return success(id, "get_fork_messages", { messages });

packages/coding-agent/src/modes/rpc/rpc-types.ts

@@ -57,6 +57,7 @@ export type RpcCommand =
 	| { id?: string; type: "export_html"; outputPath?: string }
 	| { id?: string; type: "switch_session"; sessionPath: string }
 	| { id?: string; type: "fork"; entryId: string }
+	| { id?: string; type: "clone" }
 	| { id?: string; type: "get_fork_messages" }
 	| { id?: string; type: "get_last_assistant_text" }
 	| { id?: string; type: "set_session_name"; name: string }
@@ -172,6 +173,7 @@ export type RpcResponse =
 	| { id?: string; type: "response"; command: "export_html"; success: true; data: { path: string } }
 	| { id?: string; type: "response"; command: "switch_session"; success: true; data: { cancelled: boolean } }
 	| { id?: string; type: "response"; command: "fork"; success: true; data: { text: string; cancelled: boolean } }
+	| { id?: string; type: "response"; command: "clone"; success: true; data: { cancelled: boolean } }
 	| {
 			id?: string;
 			type: "response";