Hand off a coding task from Claude Code to Codex (and back)

The problem

Sometimes the other tool is the better fit halfway through: one plan is nearly used up, you want a second opinion on a tricky fix, or you'd rather have the other model write the tests. Starting over means re-explaining the problem, what was tried, and what state the branch is in. Copy-pasting a long conversation loses structure, and the diff isn't in the conversation at all.

How Pairbar solves it

1. Open the chat menu
   On the chat you want to move, click ⋯ (or right-click it) and choose Continue → Hand off to Codex (or Hand off to Claude). With the menu open, H does the same.
2. Pairbar writes the handoff file
   It's saved in ~/.pairbar/handoffs, readable only by you. It holds the whole conversation and the repo's state at that moment: git status, the uncommitted diff, recent commits, the branch and PRs.
3. Check the 📎 Handoff chip
   The composer opens on the other app with a 📎 Handoff chip. View previews the file inside the sidebar (right-click View to open it in another app); ✕ drops it.
4. Say what's next, and send
   Type the next instruction, for example "write tests for the retry logic we just added", or send without typing anything. You can still pick the folder, branch, Worktree, model and effort as with any new chat. For Codex, Open in Codex opens a native draft; review the requested settings and press Send there.

What's in the handoff

Storage and privacy

• Handoff files live in ~/.pairbar/handoffs and are readable only by you.
• Handoffs older than 14 days are deleted whenever you make a new one.
• Pairbar itself never sends the file anywhere. The new chat reads it through Claude or Codex, which treat it like any other file they read in your project.

Handoff, fork or message?

Let the chat hand itself off

With Pairbar's tools installed, you can say "hand this off to Codex and have it write the tests" in the chat itself, or type /pairbar:handoff in Claude ($pairbar:handoff in Codex). The chat calls the handoff tool with its instruction; Pairbar writes the same handoff file as the menu does and opens the composer on the other app with the file attached and the chat's instruction typed in.

• Nothing starts until you press Send. You can edit the instruction, pick the folder, branch or worktree, or drop the handoff with ✕.
• upToTurn lets the chat stop the conversation at an earlier turn.
• With start: true the chat asks Pairbar to open the destination too; Codex still opens a draft for you to review and Send. That is always shown to you first, and asked every time: no setting or one-hour grant covers it.
• Handoffs to the composer in Settings → Integrations → Agent actions is Allow to start with, or Off. Helper chats Pairbar started can't hand off, and every request is listed in Agent activity.

Without Pairbar

Ways to carry context between the two tools by hand:

• Ask the current chat to summarise, for example "write a handoff note to HANDOFF.md with what we tried and what's left", then point the other tool at it. Works well; the summary is only as complete as the model makes it, and you add the git state yourself.
• Shared project instructions, such as CLAUDE.md for Claude Code and AGENTS.md for Codex, carry lasting project knowledge (not the current conversation).
• Commit or push a WIP branch so the other tool starts from the same code; the reasoning behind it still has to be re-explained.