feat(coding-agent): add set_session_name RPC command (#1075)

- Add set_session_name command with empty name validation
- Expose sessionName in get_state response
- Add setSessionName() to AgentSession and RpcClient
- Document in docs/rpc.md

packages/coding-agent/src/core/agent-session.ts

@@ -590,6 +590,11 @@ export class AgentSession {
 		return this.sessionManager.getSessionId();
 	}
 
+	/** Current session display name, if set */
+	get sessionName(): string | undefined {
+		return this.sessionManager.getSessionName();
+	}
+
 	/** Scoped models for cycling (from --models flag) */
 	get scopedModels(): ReadonlyArray<{ model: Model<any>; thinkingLevel: ThinkingLevel }> {
 		return this._scopedModels;
@@ -2181,6 +2186,13 @@ export class AgentSession {
 		return true;
 	}
 
+	/**
+	 * Set a display name for the current session.
+	 */
+	setSessionName(name: string): void {
+		this.sessionManager.appendSessionInfo(name);
+	}
+
 	/**
 	 * Create a fork from a specific entry.
 	 * Emits before_fork/fork session events to extensions.

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

@@ -362,6 +362,13 @@ export class RpcClient {
 		return this.getData<{ text: string | null }>(response).text;
 	}
 
+	/**
+	 * Set the session display name.
+	 */
+	async setSessionName(name: string): Promise<void> {
+		await this.send({ type: "set_session_name", name });
+	}
+
 	/**
 	 * Get all messages in the session.
 	 */

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

@@ -349,6 +349,7 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 					followUpMode: session.followUpMode,
 					sessionFile: session.sessionFile,
 					sessionId: session.sessionId,
+					sessionName: session.sessionName,
 					autoCompactionEnabled: session.autoCompactionEnabled,
 					messageCount: session.messages.length,
 					pendingMessageCount: session.pendingMessageCount,
@@ -490,6 +491,15 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 				return success(id, "get_last_assistant_text", { text });
 			}
 
+			case "set_session_name": {
+				const name = command.name.trim();
+				if (!name) {
+					return error(id, "set_session_name", "Session name cannot be empty");
+				}
+				session.setSessionName(name);
+				return success(id, "set_session_name");
+			}
+
 			// =================================================================
 			// Messages
 			// =================================================================

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

@@ -58,6 +58,7 @@ export type RpcCommand =
 	| { id?: string; type: "fork"; entryId: string }
 	| { id?: string; type: "get_fork_messages" }
 	| { id?: string; type: "get_last_assistant_text" }
+	| { id?: string; type: "set_session_name"; name: string }
 
 	// Messages
 	| { id?: string; type: "get_messages" }
@@ -96,6 +97,7 @@ export interface RpcSessionState {
 	followUpMode: "all" | "one-at-a-time";
 	sessionFile?: string;
 	sessionId: string;
+	sessionName?: string;
 	autoCompactionEnabled: boolean;
 	messageCount: number;
 	pendingMessageCount: number;
@@ -185,6 +187,7 @@ export type RpcResponse =
 			success: true;
 			data: { text: string | null };
 	  }
+	| { id?: string; type: "response"; command: "set_session_name"; success: true }
 
 	// Messages
 	| { id?: string; type: "response"; command: "get_messages"; success: true; data: { messages: AgentMessage[] } }