Feature proposal: scheduled prompt tools and durable cron tasks

Summary

I built a prototype that adds Claude Code-style scheduled prompt support to Codex. The implementation is available on my fork:

• Branch: https://github.com/guangxiangdebizi/codex/tree/codex/scheduled-tasks
• Commit: https://github.com/guangxiangdebizi/codex/commit/8393465

I tried to open a PR from guangxiangdebizi:codex/scheduled-tasks into openai/codex:main, but GitHub shows that PR creation is limited to repository collaborators, so I am opening this issue to share the module and ask whether maintainers are interested in reviewing it.

What the prototype adds

• New built-in tools:
• cron_create
• cron_list
• cron_delete
• A new Rust crate: codex-rs/scheduled-tasks
• Session-local scheduled prompts that enqueue synthetic user messages into the existing pending-input turn queue
• Durable scheduled prompts persisted under CODEX_HOME/scheduled_tasks.json
• A codex cron CLI with create, list, delete, tick, and daemon subcommands
• A durable wake-up path that can be driven by an external cron/systemd timer through codex cron tick

Motivation

For long-running local agent workflows, it is useful to have scheduled check-ins that survive beyond one active turn. The main use case is a durable reminder/checkpoint mechanism for autonomous or semi-autonomous workflows where the agent should periodically resume a thread and inspect external state, logs, or experiment progress.

This mirrors the rough shape of Claude Code's scheduled-task idea:

• session-only tasks for in-memory reminders while the session is alive
• durable tasks persisted outside the live session
• scheduled wakeups added as normal user input rather than interrupting active work

Implementation notes

The prototype intentionally keeps the first version conservative:

• cron expressions are parsed as 5-field local-time cron specs
• durable state is plain JSON under CODEX_HOME
• root-thread-only tool handling prevents subagents from creating or deleting scheduled tasks
• codex cron tick drains due durable tasks and resumes their target thread with codex exec resume

Validation

• git diff --check passed locally
• I could not run Rust compile/tests in the environment where this was built because cargo/rustc were not installed there

Ask

Would maintainers be open to this kind of scheduled prompt module in Codex? If yes, could someone with collaborator permissions either open a PR from my fork/branch or advise what shape would make the proposal easier to review?