claude-task-master/.changeset/fix-file-locking.md

task-master-ai

task-master-ai
patch

Fix race condition when multiple Claude Code windows write to tasks.json simultaneously

• Add cross-process file locking to prevent concurrent write collisions
• Implement atomic writes using temp file + rename pattern to prevent partial writes
• Re-read file inside lock to get current state, preventing lost updates from stale snapshots
• Add stale lock detection and automatic cleanup (10-second timeout)
• Export withFileLock and withFileLockSync utilities for use by other modules

This fix prevents data loss that could occur when multiple Task Master instances (e.g., multiple Claude Code windows) access the same tasks.json file concurrently.