Method read

packages/agent-core/src/services/fs/fsService.ts:163–226

(sessionId: string, req: FsReadRequest)

  }

  async read(sessionId: string, req: FsReadRequest): Promise<FsReadResponse> {
    const session = await this.sessions.get(sessionId);
    const cwd = session.metadata.cwd;
    const safe = await resolveSafePath(cwd, req.path);

    let st: import('node:fs').Stats;
    try {
      st = await fs.stat(safe.absolute);
    } catch (err) {
      throw mapStatError(err, req.path);
    }
    if (st.isDirectory()) {
      throw new FsIsDirectoryError(req.path);
    }
    if (st.size > FS_READ_MAX_BYTES) {
      throw new FsTooLargeError(req.path, st.size);
    }

    const sampleSize = Math.min(FS_BINARY_SAMPLE_BYTES, st.size);
    const sample = await readFileRange(safe.absolute, 0, sampleSize);
    const isBinaryHeuristic = detectBinary(sample);

    if (isBinaryHeuristic && req.encoding === 'utf-8') {

      throw new FsIsBinaryError(req.path);
    }

    const effectiveLength = Math.min(req.length, st.size - req.offset);
    const bytes =
      effectiveLength <= 0
        ? Buffer.alloc(0)
        : await readFileRange(
            safe.absolute,
            req.offset,
            req.offset + effectiveLength,
          );

    const encoding: 'utf-8' | 'base64' =
      req.encoding === 'base64' || (req.encoding === 'auto' && isBinaryHeuristic)
        ? 'base64'
        : 'utf-8';
    const content = encoding === 'utf-8' ? bytes.toString('utf-8') : bytes.toString('base64');
    const truncated = req.offset + effectiveLength < st.size;

    const mime = guessMime(safe.relative, isBinaryHeuristic);
    const languageId = encoding === 'utf-8' ? guessLanguageId(safe.relative) : undefined;
    const etag = buildEtag(st);

    const out: FsReadResponse = {
      path: safe.relative,
      content,
      encoding,
      size: st.size,
      truncated,
      etag,
      mime,
      is_binary: isBinaryHeuristic,
    };