batonpass

Automatic, local, verbatim session handoff between Codex and Claude Code.

Finish a turn in Codex, open Claude Code in the same repository, and it already knows what Codex just did: the last exchanges word for word, the goal, the pull requests and the state of the branch. The same works from Claude Code to Codex. No command to remember, no hosted service, no model-written summary.

How it works

• Stop hook (both tools, runs in the background): reads the new lines of the session transcript, removes secrets, stores the dialogue in a local SQLite ledger (~/.baton/baton.db) and renders a numbered snapshot of the project.
• SessionStart hook (both tools): injects the latest brief, about 2,000 tokens, as context. No network call, no model call.
• PreCompact hook: stores everything before the tool compacts its own context.
• Sessions are grouped by git remote, so clones and worktrees of one repository share one history.

The brief is framed as prior context, not instructions, and always tells the new session how to look further back: baton search "<words>", baton show --full, or the original session (codex resume <id>, claude --resume <id>).

Install

Requires Node.js 24 or later.

npm install -g @batonpass/cli
baton install --dry-run
baton install

baton install merges three hooks into ~/.claude/settings.json and ~/.codex/hooks.json, installs the baton-resume skill for both tools, keeps a backup of every file it changes, and records what it added so baton uninstall removes exactly that. Codex asks you to review and trust new hooks once: run /hooks in Codex.

Existing history is read on the first baton ingest (the last 30 days, at most 64 MiB per transcript).

Commands

Command	What it does
baton status	Projects, sessions per tool, snapshot age, Jev spend today
baton show [--full] [--project id] [--json]	Print the latest snapshot for this repository
baton ingest [--all] [--project id]	Read new transcript lines now and refresh snapshots
baton search <words…>	Full-text search over this project's redacted history
baton note <text…>	Pin a note into every future snapshot of this project
baton resume codex / baton resume claude	Start the other tool here with the brief as its first prompt
baton doctor [--jev]	Check Node, hooks, transcripts, ledger health and redaction counts
baton eval	Run the recall evaluation and write a scorecard
baton install / baton uninstall	Add or remove the hooks and the skill

Privacy

• Transcripts never leave your machine. The ledger lives in ~/.baton (directory 0700, database 0600).
• Tool outputs are never stored (Claude Code's compaction summaries are, and the model writes those from the whole context). Everything stored passes a secret redactor first.
• The default strategy makes no network call. The only optional network use is Jev (below) and read-only gh for open pull requests.

Details: docs/privacy.md.

Selection

The brief keeps the most recent dialogue turns verbatim until its budget is spent (recent-dialogue, the default). With a TypeSafe key you can opt in to jev-select: when the dialogue does not fit, TypeSafe's Jev model marks exchanges that are safe to cut, and only confident answers are acted on. jev.rules (experimental) extracts standing instructions into their own section.

# ~/.baton/config.toml
[select]
strategy = "jev-select"        # default "recent-dialogue"

[jev]
maxInputTokensPerDay = 2000000 # about $0.08 a day at the published price
rules = false

[aliases]
"~/old/checkout/of/web" = "github.com/acme/web"

Evaluation

baton eval rebuilds 8 synthetic multi-session histories (Codex and Claude Code mixed), renders the brief with each strategy, and asks a fresh claude -p session 64 questions about decisions, constraints, identifiers, verified results and open items: once from the brief alone, once with one baton search. Latest scorecard (evals/results, answered by Claude Haiku through claude -p):

Strategy	Recall, brief only	Recall, brief + one search	Brief tokens (avg)
no context	0.0% (0/64)	70.3% (45/64)	0
recent-dialogue (default)	71.9% (46/64)	95.3% (61/64)	1,497
jev-select	not yet measured (needs a TypeSafe key)

A release ships only when the default strategy is at least as good as recent-dialogue on both measures, beats having no context, and the run had no failed answers.

Supported transcripts

Codex rollouts (~/.codex/sessions, CLI 0.155 format) and Claude Code sessions (~/.claude/projects, 2.1.x). Readers ignore unknown line types; baton doctor reports malformed lines. Adding another agent means adding one reader: see docs/writing-a-reader.md.

License

MIT. Contributions welcome: see CONTRIBUTING.md.