We stopped letting our best model write code.
Fable 5 plans, shards, gates, and judges. A $0.76 per MTok worker builds, and this week that worker tied our flagship three for three on real agentic coding slices. The system that runs it is one file, and it is free.
Context slices
Dispatch feed
Judgment is premium. Keystrokes are a commodity. Fable writes the contract and grades the work. The worker just types, and the validator does not care who typed.
Measured, not simulated.
Three bounded coding tasks, run by real headless agents with a tool loop, an external validator, and git isolated repos. The same harness we dispatch production work with.
the rematch · agentic workers · external validator · n=3 sharded slices
what the worker seat costs · the orchestrator seat stays premium, that is the whole point
How a slice moves.
Every issue travels the same relay. Premium judgment at the ends, commodity execution in the middle.
Fable 5 orchestrates
Interviews you, writes the validation contract, shards bounded issue slices, pins scope, and judges every result.
GLM executes
44sValidator guarded slices on the cheapest capable backend. Measurably equal on sharded work, escalation only on failure.
Codex reviews
GPT 5.5 sits in a different vendor family, so the worker never grades its own homework. Blocking findings send it back.
Gemini sees
Screenshots and visual verification route to a model that can look. Text models stay blind by policy.
The actual skill, unedited.
Not a blog post about the idea. The two command files we run in Claude Code, plus install notes.
/mission, the planning half
A structured interview that ends in a reviewed packet: a validation contract with stable VAL assertions, a PRD, tracer bullet issue slices, adversarial and engineering reviews, and a hard approval gate. Nothing executes from planning.
/mission-continue, the execution half
Runs the approved packet one bounded context slice at a time: dispatch to the cheapest capable backend, structured worker handoffs, fresh context validators, and stop at boundary discipline.
The routing doctrine, embedded
The orchestrator seat stays premium. Workers route down and off vendor by default and escalate only on validator failure. The eval on this page is the doctrine paying rent.
Honest install notes
These files reference paths and gate tooling from our machine. The README marks every line you will adapt, roughly fifteen minutes to wire into your own Claude Code setup.
Get the /mission skill.
Name and email. The download appears right here, no hoops.