seeded-determinism-and-golden-vectors
Seeded determinism and golden vectors
Some output must be a pure function of a key: the daily pick every user compares with their friends, a procedurally generated layout, a shareable result someone else can verify. It has to come out identical on every device, in every timezone, on the platform build you ship next year — with no server to arbitrate. That is a stronger property than "the tests pass", and it needs its own discipline plus a frozen oracle to keep it.
testing-strategy owns how you test pure logic (seeded fuzz against an independent oracle, injected
Clock). This skill owns what makes the output reproducible in the first place, and the committed
vector table that pins it.
A golden vector is not a golden image. Vectors are data fingerprints for a pure generator,
asserted by dart test with no widget binding; reference PNGs of rendered UI belong to
widget-golden-and-a11y-testing, and re-blessing them is the separate ritual in
run-goldens-rebaseline. The two share only the word "golden" and the rule that a gate must never
regenerate what it checks.