Function call

src/tools/FileEditTool/FileEditTool.ts:387–574

(
    input: FileEditInput,
    {
      readFileState,
      userModified,
      updateFileHistoryState,
      dynamicSkillDirTriggers,
    },
    _,
    parentMessage,
  )

    )
  },
  async call(
    input: FileEditInput,
    {
      readFileState,
      userModified,
      updateFileHistoryState,
      dynamicSkillDirTriggers,
    },
    _,
    parentMessage,
  ) {
    const { file_path, old_string, new_string, replace_all = false } = input

    // 1. Get current state
    const fs = getFsImplementation()
    const absoluteFilePath = expandPath(file_path)

    // Discover skills from this file's path (fire-and-forget, non-blocking)
    // Skip in simple mode - no skills available
    const cwd = getCwd()
    if (!isEnvTruthy(process.env.CLAUDE_CODE_SIMPLE)) {
      const newSkillDirs = await discoverSkillDirsForPaths(
        [absoluteFilePath],
        cwd,
      )
      if (newSkillDirs.length > 0) {
        // Store discovered dirs for attachment display
        for (const dir of newSkillDirs) {
          dynamicSkillDirTriggers?.add(dir)
        }
        // Don't await - let skill loading happen in the background
        addSkillDirectories(newSkillDirs).catch(() => {})
      }

      // Activate conditional skills whose path patterns match this file
      activateConditionalSkillsForPaths([absoluteFilePath], cwd)
    }

    await diagnosticTracker.beforeFileEdited(absoluteFilePath)

    // Ensure parent directory exists before the atomic read-modify-write section.
    // These awaits must stay OUTSIDE the critical section below — a yield between
    // the staleness check and writeTextContent lets concurrent edits interleave.
    await fs.mkdir(dirname(absoluteFilePath))
    if (fileHistoryEnabled()) {
      // Backup captures pre-edit content — safe to call before the staleness
      // check (idempotent v1 backup keyed on content hash; if staleness fails
      // later we just have an unused backup, not corrupt state).
      await fileHistoryTrackEdit(
        updateFileHistoryState,
        absoluteFilePath,
        parentMessage.uuid,
      )
    }

    // 2. Load current state and confirm no changes since last read
    // Please avoid async operations between here and writing to disk to preserve atomicity
    const {