How it's built

catastr is written almost entirely by Claude Code (Claude Opus). My part is direction, decisions and review. The interesting question was: how far does this go if the process is taken seriously?

By the numbers

Started on 6 October 2026
655 commits, nearly all co-authored by Claude
~94,000 lines of Rust in six crates
~1,400 tests
82 ADRs (architecture decision records)

The first month in Forgejo:

Activity, 21 September – 21 October 2026

Code frequency: additions and deletions over time

What keeps it on track

A written plan. Architecture, data model and phases are in one document. The agent reads it first and must not quietly deviate from it.
ADRs for every decision. Each one records context, decision and consequences. Old ADRs are never rewritten; a changed mind gets a new one.
A task tree. Open work, observations and half-done steps live in one Org file, with states and priorities.
A definition of done. make check — format, clippy, tests — has to pass before anything is committed.
Independent audits. Separate, read-only agents review the code for drift from the plan, for bugs and for security issues.
Real data. Measurements against a real mailbox of 59,533 messages, not just test fixtures.

Why Rust

A strict compiler is a good safety net when most of the code is generated. Rust also gives one core for the daemon, the browser (WASM) and Android.