[Tielem]

"0.19.x means implements spec 0.19" lived only in prose — CLAUDE.md and the changelog headers. That left it one typo from being silently false.

Three ways it drifted, none of which failed a build

Scenario	Result
Spec → 0.20.0, repo implements it, heading dated ## [0.19.4]	Claims 0.19, implements 0.20
Spec still 0.19, a bug fix dated ## [0.20.0]	Claims a spec that does not exist
Pins bumped to 0.20.x packages, changelog left at 0.19.x	Version and dependencies disagree

The check

Each implementation carries a SPEC_VERSION file naming the spec it implements, and scripts/check-version-parity.sh runs first in CI:

1. the minor of the top CHANGELOG.md version equals the minor of SPEC_VERSION
2. every Utos.* package pin is on that same minor — a package on a different minor is on a different spec line

Checked at PR time rather than release time, because at release time the mistake is a tag and a published artifact that cannot be taken back.

Verified by breaking it

Both halves, not just the happy path:

error: CHANGELOG.md names 0.20.0 but SPEC_VERSION says this repo implements 0.19.0.
       The minor is the contract: 0.20.x must mean implements spec 0.20.
       Either the version is wrong, or SPEC_VERSION was not updated when the spec moved.

error: Utos.Workflow is pinned at 0.20.1, but this repo implements spec 0.19.0.
       A package on a different minor is on a different spec line.

The message names which of the two is likely wrong, since "these disagree" is the easy half and "which one moved" is what a reader actually needs.

The script is runnable locally — scripts/check-version-parity.sh — so a version change can be checked before pushing.