Method diff

packages/agent-core/src/services/fs/fsGitService.ts:134–212

(sessionId: string, req: FsDiffRequest)

  }

  async diff(sessionId: string, req: FsDiffRequest): Promise<FsDiffResponse> {
    const session = await this.sessions.get(sessionId);
    const cwd = session.metadata.cwd;
    const realCwd = await fs.realpath(cwd);
    const safe = await resolveSafePath(realCwd, req.path);
    const rel = safe.relative;

    const insideRes = await runCommand('git', ['rev-parse', '--is-inside-work-tree'], realCwd);
    if (insideRes.exitCode !== 0 || insideRes.stdout.trim() !== 'true') {
      throw new FsGitUnavailableError(
        realCwd,
        insideRes.stderr.trim() || `git rev-parse exit ${insideRes.exitCode}`,
      );
    }

    const statusRes = await runCommand(
      'git',
      ['status', '--porcelain=v1', '--', rel],
      realCwd,
    );
    if (statusRes.exitCode !== 0) {
      throw new FsGitUnavailableError(
        realCwd,
        statusRes.stderr.trim() || `git status exit ${statusRes.exitCode}`,
      );
    }
    const untracked = statusRes.stdout.startsWith('??');

    // A repo with no commits yet has no HEAD to diff against — every changed
    // file is all-new there, same as the untracked case.
    const headRes = await runCommand('git', ['rev-parse', '--verify', '--quiet', 'HEAD'], realCwd);
    const hasHead = headRes.exitCode === 0;

    // An untracked file has no HEAD side; diff it against /dev/null so the UI
    // gets an all-added hunk. `git diff --no-index` exits 1 when files differ.
    let diffRes: RunResult;
    if (untracked || !hasHead) {
      diffRes = await runCommand(
        'git',
        ['diff', '--no-color', '--no-index', '--', '/dev/null', rel],
        realCwd,
      );
      if (diffRes.exitCode !== 0 && diffRes.exitCode !== 1) {
        throw new FsGitUnavailableError(
          realCwd,
          diffRes.stderr.trim() || `git diff exit ${diffRes.exitCode}`,
        );
      }
    } else {
      diffRes = await runCommand(
        'git',
        ['diff', '--no-color', 'HEAD', '--', rel],
        realCwd,
      );
      if (diffRes.exitCode !== 0) {
        throw new FsGitUnavailableError(
          realCwd,
          diffRes.stderr.trim() || `git diff exit ${diffRes.exitCode}`,