Rules

Go runs only through docker compose run --rm <test|vet|fmt|build>; the merge gate is docker build ..
Tests first, in their own commit; the implementation follows in the next. A re-pin of seeded output is its own commit.
One-line commit messages: no ticket prefix, no repo name, no authorship trailers.
Hard tabs. No comment by default; delete a restatement, a rationale, history, or a file preamble.
One spelling per result: reject the other at New, and let the error name the spelling to use.
A standing choice a reader would relitigate goes under Decisions in the README, not in a comment.
A README example is a json block that loads and renders as a category; readme_test.go runs every one.
Cyclomatic complexity is gated at 14: the table-shaped dispatches (eachToken, calc.factor, walkPath) sit at 13–14 and stay whole; anything else that reaches 14 is decomposed.

Deferred

Shipped-data de-duplication (2026-09-02). email.json's local is a drifted copy of username.json, and no shipped file yet uses a held path, an operand or a reference. Fixed in the data fill before the first tag, when the shipped set is rewritten anyway; premise: nothing depends on the shipped data's shape until then. Not raised in review before that.