CLI: Implement Claude Code-style /rewind with checkpoint restore + context summarize modes

What variant of Codex are you using?

CLI

What feature would you like to see?

Implement a Codex CLI feature that matches the Claude Code checkpoint/rewind model:

• Trigger rewind through both /rewind and Esc + Esc.
• Open a rewind menu that lists recent checkpoints (session message points).
• Add restore modes:
• restore code and conversation (both)
• restore conversation only
• restore code only
• summarize from this message (compact forward context without changing files)
• After restore/summarize, put the selected message back into the input so users can resend/edit it.
• Track state at checkpoint granularity and keep checkpoints available in resumed sessions.
• Use existing retention/cleanup behavior for historical checkpoints.
• Do not touch manual edits that were not produced by Codex file-edit actions.

Why this is needed

I reviewed Claude Code behavior from official docs:

• checkpointing says rewind is opened by Esc + Esc or /rewind and presents actions:
• restore code + conversation
• restore conversation
• restore code
• summarize from selected message
• Checkpoints are created before each Claude edit and each user prompt creates a checkpoint.
• Checkpoints persist across sessions and are cleaned up with session cleanup (~30 days, configurable).
• Rewind/summarize is a local safety net and not a Git replacement.
• Bash/console/external changes are not reverted by rewind; only tracked file-edit operations are included.

Expected behavior in Codex

• Safe rollback of both transcript history and working tree edits to a chosen checkpoint.
• Optional code-preview before applying a checkpoint revert.
• Keep rollback behavior non-destructive for unrelated local changes and allow users to rework from the restored prompt quickly.

Related issue

• Existing closely related feature request: https://github.com/openai/codex/issues/11626

Additional notes

Current Codex backtrack already rewinds conversation context; this feature request is to make it parity-level with Claude Code's checkpoint model including code restore and summarize mode in the same command.