Harness Engineering
A harness that makes AI-driven development fast and safe at once
Context
I was building Pervis alone, which made engineering speed the same thing as business speed.
Problem
Agent-driven development is fast, but without guarantees on quality and consistency the review and rework costs eat the gains. The team needed a system that delivered both speed and safety.
How I solved it
- Designed the gates around baselines — complexity, circular dependencies, migration integrity and more are pinned to baseline files, so existing debt passes while new violations are blocked
- Wired 25 hooks across 8 lifecycle points (edit, commit, compaction, exit) so an agent cannot route around the rules
- Structured what agents read: 17 domain rule documents plus per-branch session state, preserved across context compaction
- Split roles into 19 agents across three tiers — planning, execution, tooling — and isolated parallel work with worktrees and locks
- Watched spec-to-code drift on a nightly workflow, and cut runaway agent loops with a circuit breaker
Result
- All product work on Pervis (100%) now runs through the AI-driven workflow
- Shipped a feature scoped at three months under standard estimation in three weeks
- Runs continuously at 135 verification scripts, 25 hooks, and 19 agents
Standard estimate3 months
Actual3 weeks
Impact
One person can now carry every layer of the product at a workable pace.