bjj-scheduler
GymClass
Gym management app. Devin shipped a Gymdesk import wizard, schedule-from-photo and rank systems as stacked PRs.
PR #276 →A talk for developers
Build great things
with Devin
What changes when every developer has an AI software engineer with its own computer, working next to them.
Horacio Herrerahoracioh.com
01 The shift
You stop typing every line and start directing the work.
Autocomplete
Suggests the next few lines while you type.
Chat assistant
Answers questions. You copy, paste, run and fix.
Devin
Takes the whole task: plans, codes, runs, tests, and opens a pull request.
02 Its own computer
A teammate with a full dev machine
Every session runs on its own VM with a shell, editor, browser and desktop. Devin installs dependencies, runs your app and your tests, and checks the result in the browser.
H
You from your phone
Add a “schedule from photo” option to the class import wizard.D
Devin
On it. I’ll read the wizard code first.
- Explored repo, found the import flow
- Implemented upload and parsing step
- Lint, types and tests pass
- Clicking through it in the browser
03 Start from anywhere
Meet it where you already work
Web & mobile
Start and steer sessions from a browser or your phone.
Slack & Teams
Mention Devin in a thread and it replies with progress.
@Devin fix the flaky testLinear & Jira
Hand off tickets straight from the backlog.
API & CLI
Create sessions from scripts, CI or your terminal.
curl -fsSL cli.devin.ai/install.shThis deck started as one message from my phone.
04 Understand first
Ask your codebase anything
Ask Devin
Questions about how your code works, answered with citations to real files. Then turn the answer into a plan and hand it to an agent session.
“How does a trial booking reach the calendar?”
DeepWiki
Auto-generated, always-current docs for every repo: architecture, key concepts and diagrams. Onboard to a new codebase in an afternoon.
deepwiki.com/<owner>/<repo>
05 Prompt to pull request
It doesn’t stop at the first commit
Devin opens the PR, then watches CI, fixes what breaks and replies to review comments until the PR is ready to merge. You review finished work.
feat: self-serve Gymdesk import wizard + schedule from photo
horacioh/bjj-scheduler · opened by Devin
Typecheck and unit tests
E2E failed, fix pushed by Devin
E2E re-run passed
2 review comments addressed
Ready to merge
06 Proof, not promises
It shows you that it works
Devin clicks through your app like a user and sends a recording with captions and auto-zoom, with idle time cut out. Watch 40 seconds instead of checking out the branch.
Import schedule
Step 3 · Upload a photo of the timetable
07 A second pair of eyes
Review and scan, not only write
Devin Review
Comment /devin review on any pull request and get bugs and risky changes flagged inline, with suggested fixes.
Code scans
Sweep a whole repo for security issues, slow queries, dead code, missing test coverage and quality problems, then let Devin fix what it finds.
08 It learns your team
Gets better every session
Knowledge
Facts about your repos and conventions, recalled when they’re relevant.
Skills & playbooks
Repeatable recipes: “how we deploy”, “how we write migrations”.
Memory
Remembers how you like to work, across every session.
Blueprints
Your environment as config, so each session boots ready to run.
09 Plugs into your stack
Connected to the tools you use
Through the MCP marketplace Devin can read the Sentry error, query the database, check the dashboard and open the spec, all in one session.
Monitoring
Sentry, Datadog, PagerDuty
Data
PostgreSQL, MySQL, MongoDB
Docs & tickets
Notion, Confluence, Linear, Jira
Your own
Any MCP server you build
10 Scale out
One developer, many sessions at once.
Parallel sessions
Fix the bug, write the docs and spike the feature at the same time.
Child sessions
Devin splits a big task, hands out the pieces and checks the results.
Workflows
Scripted pipelines for migrations and batch changes across many files or repos.
11 Automations
Work that happens while you sleep
Trigger
CI fails on main, a message in #bugs, or every morning at 7
Conditions
Only this repo, only issues labelled bug
Preflight check
A quick filter decides if it’s worth a session
Action
Devin investigates, fixes and opens a PR, or posts a summary
12 What I built with it
Real projects, real pull requests
vivienda-es
Housing law tracker
A daily automation finds Spanish housing law changes and publishes the news to Seed.
PR #25 →horacioh.com
Personal site
Rebuilt from Gatsby to Astro, with content pulled from Seed at build time.
PR #60 →seed
Seed Hypermedia
Deploy and ops fixes on the self-hosted fork of a peer-to-peer publishing app.
PR #43 →13 Getting great results
Brief it like a great teammate
Say what “done” looks like
“Tests pass and the import shows 20 classes” beats “make the import work”.
Point to the right place
Name the files, the similar feature, the doc. Context is the cheapest speed-up.
Start small, then scale
Bugs and chores first. Once you trust the loop, hand over features, then run them in parallel.
Teach it once
Turn every correction into knowledge or a skill so it never repeats the mistake.
Your turn
What will you build?
The limit is no longer how fast you can type. It’s how many good ideas you’re willing to try. Pick the project you never had time for, and start it tonight.