refactor(coding-agent): replace AgentSessionRuntimeHost with closure-based AgentSessionRuntime

- Replace AgentSessionRuntimeHost and bootstrap abstractions with AgentSessionRuntime
- Runtime creation is now closure-based via CreateAgentSessionRuntimeFactory
- Factory closes over process-global fixed inputs, recreates cwd-bound services per effective cwd
- Session config (model, thinking, tools, scoped models) re-resolved per target cwd
- CLI resource paths resolved once at startup as absolute paths
- Swap lifecycle: teardown old, create next, apply next (hard fail on creation error)
- Unified diagnostics model (info/warning/error) for args, services, session resolution, resources
- No logging or process exits inside creation/parsing logic
- Removed session_directory support
- Removed session_switch and session_fork extension events (use session_start with reason)
- Moved package/config CLI to package-manager-cli.ts
- Fixed theme init for --resume session picker
- Fixed flaky reftable footer test (content-based polling)
- Fixed silent drop of unknown single-dash CLI flags
- Added error diagnostics for missing explicit CLI resource paths
- Updated SDK docs, examples, plans, exports, tests, changelog

fixes #2753

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

@@ -47,7 +47,7 @@ import {
 	VERSION,
 } from "../../config.js";
 import { type AgentSession, type AgentSessionEvent, parseSkillBlock } from "../../core/agent-session.js";
-import type { AgentSessionRuntimeHost } from "../../core/agent-session-runtime.js";
+import type { AgentSessionRuntime } from "../../core/agent-session-runtime.js";
 import type {
 	ExtensionContext,
 	ExtensionRunner,
@@ -107,6 +107,7 @@ import {
 	setRegisteredThemes,
 	setTheme,
 	setThemeInstance,
+	stopThemeWatcher,
 	Theme,
 	type ThemeColor,
 	theme,
@@ -145,7 +146,7 @@ export interface InteractiveModeOptions {
 }
 
 export class InteractiveMode {
-	private runtimeHost: AgentSessionRuntimeHost;
+	private runtimeHost: AgentSessionRuntime;
 	private ui: TUI;
 	private chatContainer: Container;
 	private pendingMessagesContainer: Container;
@@ -257,7 +258,7 @@ export class InteractiveMode {
 	}
 
 	constructor(
-		runtimeHost: AgentSessionRuntimeHost,
+		runtimeHost: AgentSessionRuntime,
 		private options: InteractiveModeOptions = {},
 	) {
 		this.runtimeHost = runtimeHost;
@@ -1177,23 +1178,31 @@ export class InteractiveMode {
 						this.loadingAnimation = undefined;
 					}
 					this.statusContainer.clear();
-					const result = await this.runtimeHost.newSession(options);
-					if (!result.cancelled) {
-						await this.handleRuntimeSessionChange();
-						this.renderCurrentSessionState();
-						this.ui.requestRender();
+					try {
+						const result = await this.runtimeHost.newSession(options);
+						if (!result.cancelled) {
+							await this.handleRuntimeSessionChange();
+							this.renderCurrentSessionState();
+							this.ui.requestRender();
+						}
+						return result;
+					} catch (error: unknown) {
+						return this.handleFatalRuntimeError("Failed to create session", error);
 					}
-					return result;
 				},
 				fork: async (entryId) => {
-					const result = await this.runtimeHost.fork(entryId);
-					if (!result.cancelled) {
-						await this.handleRuntimeSessionChange();
-						this.renderCurrentSessionState();
-						this.editor.setText(result.selectedText ?? "");
-						this.showStatus("Forked to new session");
+					try {
+						const result = await this.runtimeHost.fork(entryId);
+						if (!result.cancelled) {
+							await this.handleRuntimeSessionChange();
+							this.renderCurrentSessionState();
+							this.editor.setText(result.selectedText ?? "");
+							this.showStatus("Forked to new session");
+						}
+						return { cancelled: result.cancelled };
+					} catch (error: unknown) {
+						return this.handleFatalRuntimeError("Failed to fork session", error);
 					}
-					return { cancelled: result.cancelled };
 				},
 				navigateTree: async (targetId, options) => {
 					const result = await this.session.navigateTree(targetId, {
@@ -1275,6 +1284,14 @@ export class InteractiveMode {
 		this.updateTerminalTitle();
 	}
 
+	private async handleFatalRuntimeError(prefix: string, error: unknown): Promise<never> {
+		const message = error instanceof Error ? error.message : String(error);
+		this.showError(`${prefix}: ${message}`);
+		stopThemeWatcher();
+		this.stop();
+		process.exit(1);
+	}
+
 	private renderCurrentSessionState(): void {
 		this.chatContainer.clear();
 		this.pendingMessagesContainer.clear();
@@ -3817,13 +3834,17 @@ export class InteractiveMode {
 			this.loadingAnimation = undefined;
 		}
 		this.statusContainer.clear();
-		const result = await this.runtimeHost.switchSession(sessionPath);
-		if (result.cancelled) {
-			return;
+		try {
+			const result = await this.runtimeHost.switchSession(sessionPath);
+			if (result.cancelled) {
+				return;
+			}
+			await this.handleRuntimeSessionChange();
+			this.renderCurrentSessionState();
+			this.showStatus("Resumed session");
+		} catch (error: unknown) {
+			await this.handleFatalRuntimeError("Failed to resume session", error);
 		}
-		await this.handleRuntimeSessionChange();
-		this.renderCurrentSessionState();
-		this.showStatus("Resumed session");
 	}
 
 	private async showOAuthSelector(mode: "login" | "logout"): Promise<void> {
@@ -4088,7 +4109,7 @@ export class InteractiveMode {
 			this.renderCurrentSessionState();
 			this.showStatus(`Session imported from: ${inputPath}`);
 		} catch (error: unknown) {
-			this.showError(`Failed to import session: ${error instanceof Error ? error.message : "Unknown error"}`);
+			await this.handleFatalRuntimeError("Failed to import session", error);
 		}
 	}
 
@@ -4432,15 +4453,19 @@ export class InteractiveMode {
 			this.loadingAnimation = undefined;
 		}
 		this.statusContainer.clear();
-		const result = await this.runtimeHost.newSession();
-		if (result.cancelled) {
-			return;
+		try {
+			const result = await this.runtimeHost.newSession();
+			if (result.cancelled) {
+				return;
+			}
+			await this.handleRuntimeSessionChange();
+			this.renderCurrentSessionState();
+			this.chatContainer.addChild(new Spacer(1));
+			this.chatContainer.addChild(new Text(`${theme.fg("accent", "✓ New session started")}`, 1, 1));
+			this.ui.requestRender();
+		} catch (error: unknown) {
+			await this.handleFatalRuntimeError("Failed to create session", error);
 		}
-		await this.handleRuntimeSessionChange();
-		this.renderCurrentSessionState();
-		this.chatContainer.addChild(new Spacer(1));
-		this.chatContainer.addChild(new Text(`${theme.fg("accent", "✓ New session started")}`, 1, 1));
-		this.ui.requestRender();
 	}
 
 	private handleDebugCommand(): void {

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

@@ -7,7 +7,7 @@
  */
 
 import type { AssistantMessage, ImageContent } from "@mariozechner/pi-ai";
-import type { AgentSessionRuntimeHost } from "../core/agent-session-runtime.js";
+import type { AgentSessionRuntime } from "../core/agent-session-runtime.js";
 import { flushRawStdout, writeRawStdout } from "../core/output-guard.js";
 
 /**
@@ -28,7 +28,7 @@ export interface PrintModeOptions {
  * Run in print (single-shot) mode.
  * Sends prompts to the agent and outputs the result.
  */
-export async function runPrintMode(runtimeHost: AgentSessionRuntimeHost, options: PrintModeOptions): Promise<number> {
+export async function runPrintMode(runtimeHost: AgentSessionRuntime, options: PrintModeOptions): Promise<number> {
 	const { mode, messages = [], initialMessage, initialImages } = options;
 	let exitCode = 0;
 	let session = runtimeHost.session;
@@ -124,6 +124,9 @@ export async function runPrintMode(runtimeHost: AgentSessionRuntimeHost, options
 		}
 
 		return exitCode;
+	} catch (error: unknown) {
+		console.error(error instanceof Error ? error.message : String(error));
+		return 1;
 	} finally {
 		unsubscribe?.();
 		await runtimeHost.dispose();

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

@@ -12,7 +12,7 @@
  */
 
 import * as crypto from "node:crypto";
-import type { AgentSessionRuntimeHost } from "../../core/agent-session-runtime.js";
+import type { AgentSessionRuntime } from "../../core/agent-session-runtime.js";
 import type {
 	ExtensionUIContext,
 	ExtensionUIDialogOptions,
@@ -43,7 +43,7 @@ export type {
  * Run in RPC mode.
  * Listens for JSON commands on stdin, outputs events and responses on stdout.
  */
-export async function runRpcMode(runtimeHost: AgentSessionRuntimeHost): Promise<never> {
+export async function runRpcMode(runtimeHost: AgentSessionRuntime): Promise<never> {
 	takeOverStdout();
 	let session = runtimeHost.session;
 	let unsubscribe: (() => void) | undefined;
@@ -628,29 +628,49 @@ export async function runRpcMode(runtimeHost: AgentSessionRuntimeHost): Promise<
 	}
 
 	const handleInputLine = async (line: string) => {
+		let parsed: unknown;
 		try {
-			const parsed = JSON.parse(line);
+			parsed = JSON.parse(line);
+		} catch (parseError: unknown) {
+			output(
+				error(
+					undefined,
+					"parse",
+					`Failed to parse command: ${parseError instanceof Error ? parseError.message : String(parseError)}`,
+				),
+			);
+			return;
+		}
 
-			// Handle extension UI responses
-			if (parsed.type === "extension_ui_response") {
-				const response = parsed as RpcExtensionUIResponse;
-				const pending = pendingExtensionRequests.get(response.id);
-				if (pending) {
-					pendingExtensionRequests.delete(response.id);
-					pending.resolve(response);
-				}
-				return;
+		// Handle extension UI responses
+		if (
+			typeof parsed === "object" &&
+			parsed !== null &&
+			"type" in parsed &&
+			parsed.type === "extension_ui_response"
+		) {
+			const response = parsed as RpcExtensionUIResponse;
+			const pending = pendingExtensionRequests.get(response.id);
+			if (pending) {
+				pendingExtensionRequests.delete(response.id);
+				pending.resolve(response);
 			}
+			return;
+		}
 
-			// Handle regular commands
-			const command = parsed as RpcCommand;
+		const command = parsed as RpcCommand;
+		try {
 			const response = await handleCommand(command);
 			output(response);
-
-			// Check for deferred shutdown request (idle between commands)
 			await checkShutdownRequested();
-		} catch (e: any) {
-			output(error(undefined, "parse", `Failed to parse command: ${e.message}`));
+		} catch (commandError: unknown) {
+			output(
+				error(
+					command.id,
+					command.type,
+					commandError instanceof Error ? commandError.message : String(commandError),
+				),
+			);
 		}
 	};