Red Robot K.K. · Release ·
Replay Doctor
Replay Doctor is the tool we built to read our own agent bill, and today it is yours. It runs on your machine, reads the transcripts your coding agent already wrote, and names the turn the provider re-read everything at write prices.
It lives at replay.doctor and was incubated and supported by Red Robot K.K. Source available today, Apache 2.0 on 2029-09-06. Nothing leaves your machine, and every figure on this page carries the date it was read.
Install
macOS and Linux. The script verifies a checksum and refuses to build from source when it cannot. Read it before you run it.
Version at release
replay 0.5.4
The version that produced the figures below, on the date beside them.
Why we built it, in our own numbers
Replay came out of running coding agents on client work and wanting to know where the money went. This is the maintainer’s own corpus, read by replay 0.5.4 on 2026-09-12. One machine, one person’s habits, so run it on yours before you quote it.
- 119
- Sessions
1,881 transcripts, priced at list rates.
- $4039.23
- Total
Median task $0.79, p90 $7.79. No average, because the spread is the point.
- $199.77
- Paid twice
Re-billed because a prompt cache broke and nothing said so. Money already spent, with the turn named.
- 5%
- Of the total
Not a forecast. The share of this corpus, on this date.
What is being released
One Go binary, four commands that matter on the first day, and the documentation that goes with them. It reads Claude Code and Codex transcripts. Cursor keeps no cache fields in its store, so it is out of scope and the documentation says so.
- replay cost
- Prices every session in a transcript directory at list rates and reports the total, the median task, the p90 task, and the amount that was billed twice because a prompt cache broke.
- replay diff
- Names the turn the cache stopped matching and what changed on that turn: a timestamp, a reordered tool list, a history the client re-rendered.
- replay context
- Scores a different context layout against the same recorded session, so a change can be priced before it is made.
- replay doctor
- Says what is on this machine, which transcripts it can read, and what to run next. Names paths, never content.
The licence, in plain words
Replay is published under the Business Source License, BSL 1.1. The source is public, you can read it, build it, run it and change it, and the diagnosis is free. What the licence withholds until 2029-09-06 is offering Replay itself as a hosted service to third parties. On that date the licence converts to Apache 2.0 and the restriction ends.
So this is a source-available release, not an open-source one until that date, and we would rather say that plainly than borrow a label the licence does not earn. Everything else about how the project is run is what people expect from an open project: public repository, public issues, public corrections, public evidence.
How the project will be run
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Corrections are dated and public
When a published figure is wrong, the correction ships as a new dated file and the wrong number stays visible with a line through it. Three have been published already, and they are on the product page.
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Nothing leaves your machine
No account, no telemetry, no first-run prompt. The binary reaches the network for four commands you type, and the surfaces page lists every file, socket and process it touches.
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Issues are the front door
Bugs, questions and feature ideas go through the public repository. Security problems go through a private advisory and are acknowledged within three working days.
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Diagnosis stays free
Running the tool costs nothing and no entitlement check will enter the binary. The one thing for sale is a week of one operator reading a team’s corpus with them, and there is no price page because nobody has paid for one yet.
Where things live
- replay.doctor The product site: documentation, FAQ, support, and every evidence file with its date.
- github.com/RedRobotKK/Replay Source, releases, issues, discussions, and the security policy.
- redrobot.jp/Replay The product page on this site: what it measures and what it got wrong in public.
- Releases Signed binaries for macOS and Linux, with the checksum the installer verifies.
Quoting this release
This page is the announcement of record. If you write about Replay, link here or to replay.doctor, quote figures with the date printed beside them, and check the corrections first, because a number you saw last week may have been retracted since.
Boilerplate
Replay Doctor (replay.doctor) is a command line tool that reads the transcripts a coding agent already keeps on disk and names the turn the prompt cache broke and what it cost. It runs locally, sends nothing, and publishes its own corrections. Incubated and supported by Red Robot K.K., a software studio in Tokyo. Source available under BSL 1.1, Apache 2.0 on 2029-09-06.
Contact and assets
Daniel Saito, founder, [email protected]. The RedRobot mark and wordmark are in the brand folder on this site; the social card for Replay is here.
