fix(coding-agent): handle missing session cwd

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

@@ -0,0 +1,59 @@
+import { existsSync } from "node:fs";
+
+export interface SessionCwdIssue {
+	sessionFile?: string;
+	sessionCwd: string;
+	fallbackCwd: string;
+}
+
+interface SessionCwdSource {
+	getCwd(): string;
+	getSessionFile(): string | undefined;
+}
+
+export function getMissingSessionCwdIssue(
+	sessionManager: SessionCwdSource,
+	fallbackCwd: string,
+): SessionCwdIssue | undefined {
+	const sessionFile = sessionManager.getSessionFile();
+	if (!sessionFile) {
+		return undefined;
+	}
+
+	const sessionCwd = sessionManager.getCwd();
+	if (!sessionCwd || existsSync(sessionCwd)) {
+		return undefined;
+	}
+
+	return {
+		sessionFile,
+		sessionCwd,
+		fallbackCwd,
+	};
+}
+
+export function formatMissingSessionCwdError(issue: SessionCwdIssue): string {
+	const sessionFile = issue.sessionFile ? `\nSession file: ${issue.sessionFile}` : "";
+	return `Stored session working directory does not exist: ${issue.sessionCwd}${sessionFile}\nCurrent working directory: ${issue.fallbackCwd}`;
+}
+
+export function formatMissingSessionCwdPrompt(issue: SessionCwdIssue): string {
+	return `cwd from session file does not exist\n${issue.sessionCwd}\n\ncontinue in current cwd\n${issue.fallbackCwd}`;
+}
+
+export class MissingSessionCwdError extends Error {
+	readonly issue: SessionCwdIssue;
+
+	constructor(issue: SessionCwdIssue) {
+		super(formatMissingSessionCwdError(issue));
+		this.name = "MissingSessionCwdError";
+		this.issue = issue;
+	}
+}
+
+export function assertSessionCwdExists(sessionManager: SessionCwdSource, fallbackCwd: string): void {
+	const issue = getMissingSessionCwdIssue(sessionManager, fallbackCwd);
+	if (issue) {
+		throw new MissingSessionCwdError(issue);
+	}
+}