Parallel Task Execution

The defining advantage of Codex Cloud is parallelism. Because each task runs in its own microVM, you can submit multiple tasks simultaneously with zero interference. One task refactors the payment module. Another writes tests for the user module. A third updates documentation. All three execute concurrently, each in its own isolated environment with its own git worktree.

Effective parallelism requires task independence. Tasks that modify the same files will produce conflicting diffs that are painful to merge. The discipline is the same as assigning work to a team of developers: decompose the project into non-overlapping work streams, assign each stream to a thread, and merge the results after review. Codex Cloud manages the git worktrees automatically — each thread gets its own branch.

# Submit parallel tasks via CLI
codex cloud "refactor src/auth/ to use JWT refresh tokens" &
codex cloud "add comprehensive tests for src/payments/" &
codex cloud "update API documentation for all /v2 endpoints" &

# Monitor all running tasks
codex cloud status

# Review each task's output independently
codex cloud diff <auth-task-id>
codex cloud diff <payments-task-id>
codex cloud diff <docs-task-id>

1. Decompose the work List all tasks and identify which modify overlapping files. Group overlapping tasks into a single thread; parallelize the rest.
2. Submit in parallel Launch each independent task as a separate cloud thread. Use descriptive prompts so each thread has clear scope.
3. Review and merge Review each thread's diff independently. Merge branches in dependency order — infrastructure first, then features, then tests.