apps/desktop/src/main/project-context-root.ts

import { constants } from 'node:fs';
import { access, stat } from 'node:fs/promises';

export const SESSION_WORKSPACE_UNAVAILABLE_CODE = 'SESSION_WORKSPACE_UNAVAILABLE';

export function isSessionWorkspaceUnavailableError(error: unknown): boolean {
  if (!error || typeof error !== 'object') return false;
  const event = error as { code?: unknown; message?: unknown };
  return event.code === SESSION_WORKSPACE_UNAVAILABLE_CODE
    || (typeof event.message === 'string' && event.message.includes(`${SESSION_WORKSPACE_UNAVAILABLE_CODE}:`));
}

export async function assertSessionWorkspaceAvailable(
  cwd: string,
): Promise<void> {
  try {
    const info = await stat(cwd);
    if (!info.isDirectory()) throw new Error('Not a directory.');
    await access(cwd, constants.R_OK | constants.X_OK);
    return;
  } catch {
    // Fall through to the stable cross-process error contract.
  }

  const error = new Error(
    `${SESSION_WORKSPACE_UNAVAILABLE_CODE}: Working directory does not exist or is not accessible.`,
  );
  (error as Error & { code: string }).code = SESSION_WORKSPACE_UNAVAILABLE_CODE;
  throw error;
}

export async function resolveProjectContextRoot(
  sessionId: unknown,
  deps: {
    currentProjectRoot(): Promise<string>;
    readSessionCwd(sessionId: string): Promise<string>;
  },
): Promise<string> {
  if (sessionId === undefined) return deps.currentProjectRoot();
  if (typeof sessionId !== 'string' || sessionId.length === 0) {
    throw new Error('Invalid project-context session id.');
  }

  const cwd = await deps.readSessionCwd(sessionId);
  await assertSessionWorkspaceAvailable(cwd);
  return cwd;
}