be·lay·/bəˈlā/·verbTo secure a climber by controlling the rope, so that a fall is caught.
A Claude Code plugin for people learning to build software, and for engineers new to a codebase. You do the work. It coaches, runs the tests, and keeps the record. You earn delegation one skill at a time.
/plugin marketplace add sethatwood/belay /plugin install belay@belay
In build / Open source / Free
02 / the ground
Entry-level work was how a person became a senior. You did small real things badly, someone senior corrected you, and a few years later you weren't junior. Agents do the small real things now, and the senior's attention goes to the agent.
Every coding assistant works the same way: it does the work, you watch.
Anthropic studied that in January. Fifty-two engineers, one unfamiliar library. The group with AI help scored 17 points lower on comprehension, worst on debugging. The ones who kept their skill were the ones who asked why. A new codebase puts an engineer of any level in the same place: code they don't know yet, and an assistant that will write it for them. Read the study
Belay is the assistant where you do the work and it watches.
03 / how it works
For every step of real work, one of three things happens. Your logbook decides which. The logbook is the record of what you've done alone.
Mode 01 · unearned
The default for anything you haven't earned. Belay explains the goal, asks what you'd do, watches your diff, runs the tests, and corrects you like a senior would: "your retry can fire twice on timeout, look at line 14, what happens there?"
When you're stuck, Belay gives a hint, then a pattern from your own codebase, then pseudocode. It doesn't write the code.
Mode 02 · earned
For skills you've earned. Belay writes it. Before it merges, Belay asks you one question about it. Get it wrong and the skill drops back to unearned.
Mode 03 · mastered
For skills you've mastered: enough reviews, every answer right. Belay writes it and doesn't stop to ask.
You've written migrations alone three times. From now on I'll write them and you review.
Three unaided runs, each witnessed by a test run, a build, or a type check, and the skill is earned.
04 / the gate
On a step you haven't earned, a hook blocks Belay's edits before they happen: the edit tools, and the shell commands that write files.
A test run, a build, or a type check signs every unaided run in your logbook, and so do you, by answering one question about your own diff. Belay can't sign its own.
05 / the record
The map is the list of skills your work needs. Write a migration. Add an endpoint with validation. Verify a webhook signature. Debug a failing test. Each one starts unearned. The logbook counts your unaided runs, and at three the skill is earned.
You own it. Your team sees what you can do. The hints, the questions, and your answers stay in a journal on your machine.
It's a plain text file in your repo. You can read it, and so can anyone you hand it to.
06 / learn
Say what you want to learn. A language, a stack, or a thing you want to be able to build. Belay asks a few questions about your life, then proposes three projects you'd actually use, each sized to the time you have, each labeled with the skills it teaches. You pick one. Every skill starts unearned, so the first weeks are heavy coaching, the way a first job used to be. The first skill on every map is writing a test, so there's a witness from day one. By the end, Belay writes the boilerplate and you do the parts that matter.
New to a team? Open its repo. An engineer with ten years of experience is new again in their first week on a team. Say what you want to learn there. Belay maps the repo, finds the skills it uses that you haven't earned, and proposes real changes that teach them: a missing test, a pattern the codebase already uses that you haven't done, a gap someone senior would have fixed. Each one points at the file where it was done before. If there's no real place to learn a skill, Belay says so.
What you already know, you calibrate. Name the skills you've done before, answer two questions a senior would ask about each, and the ones you answer well start earned.
07 / the team
A senior plus a junior
An afternoon
a day
A senior plus an agent out-ships a senior plus a junior, and the junior costs the senior an afternoon a day. That's why teams stopped hiring juniors. The junior is also where the next senior comes from.
The same junior, with Belay
An hour
a week
With Belay carrying your standards, a junior costs a senior about an hour a week. Belay coaches with precedents from your own codebase.
Your team adds its own skills to the map, marks the zones that always need a human co-sign, and sets how many unaided runs earn a skill. When the hints run out, Belay writes the senior a ten-minute question instead of an afternoon of pairing.
An experienced hire runs calibration, and the skills they show they've done before start earned. The codebase's own skills they earn here, like everyone else.
Two zones are marked for a human co-sign. Version one records them, and the CI check that enforces them comes next.
| can do it alone | Ana | Theo | Ruth | Sam |
|---|---|---|---|---|
| write-a-migration | can do it alone | can do it alone | can do it alone | not yet |
| add-route | can do it alone | can do it alone | can do it alone | can do it alone |
| verify-webhook-signature | can do it alone | not yet | can do it alone | not yet |
| debug-a-failing-test | can do it alone | can do it alone | not yet | can do it alone |
| release-rollback | not yet | not yet | can do it alone | not yet |
Next: a team map read from everyone's committed logbook, showing who can do what alone and which skills only one person holds.
Hire the junior again.
At an hour of senior time a week, you can afford to. In five years your next senior has to come from somewhere.
08 / scope
09 / the author
I ran the team that went from a dozen engineers to two.
In 2023 we peaked at about twelve. Then the layoff, and I was in it. Ten months later they asked me back, and for a year and a half it was me alone. Now it's two of us and Claude Code, and we out-ship the twelve. I measured it and published the method.
A senior plus an agent beats a senior plus a junior, and the junior costs the senior an afternoon a day. Every engineering leader I know has done that math. Nobody says out loud where it leaves the person who would have been the junior, or where the next senior comes from.
I've hired and grown engineers at multiple companies. I know what it costs to make a senior, and what it's worth. The entry-level job that made them is going away, and the people who needed it are going to be angry.
Everything I use does the work for me.
I'm building the tool that makes me earn it.
You climb. It holds the rope.