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/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();