feat(coding-agent): complete steer()/followUp() migration

- Update settings-manager with steeringMode/followUpMode (migrates old queueMode)
- Update sdk.ts to use new mode options
- Update settings-selector UI to show both modes
- Add Alt+Enter keybind for follow-up messages
- Update RPC API: steer/follow_up commands, set_steering_mode/set_follow_up_mode
- Update rpc-client with new methods
- Delete dead code: queue-mode-selector.ts
- Update tests for new API
- Update mom/context.ts stubs
- Update web-ui example

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

@@ -173,10 +173,17 @@ export class RpcClient {
 	}
 
 	/**
-	 * Queue a message while agent is streaming.
+	 * Queue a steering message to interrupt the agent mid-run.
 	 */
-	async queueMessage(message: string): Promise<void> {
-		await this.send({ type: "queue_message", message });
+	async steer(message: string): Promise<void> {
+		await this.send({ type: "steer", message });
+	}
+
+	/**
+	 * Queue a follow-up message to be processed after the agent finishes.
+	 */
+	async followUp(message: string): Promise<void> {
+		await this.send({ type: "follow_up", message });
 	}
 
 	/**
@@ -248,10 +255,17 @@ export class RpcClient {
 	}
 
 	/**
-	 * Set queue mode.
+	 * Set steering mode.
 	 */
-	async setQueueMode(mode: "all" | "one-at-a-time"): Promise<void> {
-		await this.send({ type: "set_queue_mode", mode });
+	async setSteeringMode(mode: "all" | "one-at-a-time"): Promise<void> {
+		await this.send({ type: "set_steering_mode", mode });
+	}
+
+	/**
+	 * Set follow-up mode.
+	 */
+	async setFollowUpMode(mode: "all" | "one-at-a-time"): Promise<void> {
+		await this.send({ type: "set_follow_up_mode", mode });
 	}
 
 	/**

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

@@ -253,9 +253,14 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 				return success(id, "prompt");
 			}
 
-			case "queue_message": {
-				await session.queueMessage(command.message);
-				return success(id, "queue_message");
+			case "steer": {
+				await session.steer(command.message);
+				return success(id, "steer");
+			}
+
+			case "follow_up": {
+				await session.followUp(command.message);
+				return success(id, "follow_up");
 			}
 
 			case "abort": {
@@ -279,7 +284,8 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 					thinkingLevel: session.thinkingLevel,
 					isStreaming: session.isStreaming,
 					isCompacting: session.isCompacting,
-					queueMode: session.queueMode,
+					steeringMode: session.steeringMode,
+					followUpMode: session.followUpMode,
 					sessionFile: session.sessionFile,
 					sessionId: session.sessionId,
 					autoCompactionEnabled: session.autoCompactionEnabled,
@@ -334,12 +340,17 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 			}
 
 			// =================================================================
-			// Queue Mode
+			// Queue Modes
 			// =================================================================
 
-			case "set_queue_mode": {
-				session.setQueueMode(command.mode);
-				return success(id, "set_queue_mode");
+			case "set_steering_mode": {
+				session.setSteeringMode(command.mode);
+				return success(id, "set_steering_mode");
+			}
+
+			case "set_follow_up_mode": {
+				session.setFollowUpMode(command.mode);
+				return success(id, "set_follow_up_mode");
 			}
 
 			// =================================================================

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

@@ -18,7 +18,8 @@ import type { CompactionResult } from "../../core/compaction/index.js";
 export type RpcCommand =
 	// Prompting
 	| { id?: string; type: "prompt"; message: string; images?: ImageContent[] }
-	| { id?: string; type: "queue_message"; message: string }
+	| { id?: string; type: "steer"; message: string }
+	| { id?: string; type: "follow_up"; message: string }
 	| { id?: string; type: "abort" }
 	| { id?: string; type: "new_session"; parentSession?: string }
 
@@ -34,8 +35,9 @@ export type RpcCommand =
 	| { id?: string; type: "set_thinking_level"; level: ThinkingLevel }
 	| { id?: string; type: "cycle_thinking_level" }
 
-	// Queue mode
-	| { id?: string; type: "set_queue_mode"; mode: "all" | "one-at-a-time" }
+	// Queue modes
+	| { id?: string; type: "set_steering_mode"; mode: "all" | "one-at-a-time" }
+	| { id?: string; type: "set_follow_up_mode"; mode: "all" | "one-at-a-time" }
 
 	// Compaction
 	| { id?: string; type: "compact"; customInstructions?: string }
@@ -69,7 +71,8 @@ export interface RpcSessionState {
 	thinkingLevel: ThinkingLevel;
 	isStreaming: boolean;
 	isCompacting: boolean;
-	queueMode: "all" | "one-at-a-time";
+	steeringMode: "all" | "one-at-a-time";
+	followUpMode: "all" | "one-at-a-time";
 	sessionFile?: string;
 	sessionId: string;
 	autoCompactionEnabled: boolean;
@@ -85,7 +88,8 @@ export interface RpcSessionState {
 export type RpcResponse =
 	// Prompting (async - events follow)
 	| { id?: string; type: "response"; command: "prompt"; success: true }
-	| { id?: string; type: "response"; command: "queue_message"; success: true }
+	| { id?: string; type: "response"; command: "steer"; success: true }
+	| { id?: string; type: "response"; command: "follow_up"; success: true }
 	| { id?: string; type: "response"; command: "abort"; success: true }
 	| { id?: string; type: "response"; command: "new_session"; success: true; data: { cancelled: boolean } }
 
@@ -125,8 +129,9 @@ export type RpcResponse =
 			data: { level: ThinkingLevel } | null;
 	  }
 
-	// Queue mode
-	| { id?: string; type: "response"; command: "set_queue_mode"; success: true }
+	// Queue modes
+	| { id?: string; type: "response"; command: "set_steering_mode"; success: true }
+	| { id?: string; type: "response"; command: "set_follow_up_mode"; success: true }
 
 	// Compaction
 	| { id?: string; type: "response"; command: "compact"; success: true; data: CompactionResult }