1 changed files with 13 additions and 0 deletions
@@ -65,6 +65,19 @@ Each of these produced a wrong conclusion before it was written down.
    conclusion drawn from it describes the wrong tree. Confirm `git rev-parse --show-toplevel`
    is the tree you think it is before trusting any git output.

+13. **Run the repository's PINNED tool version.** `npx <tool>` resolves a local `node_modules`
+    install when one is present and fetches the latest release when one is not, so the same
+    command answers differently depending on where it ran. A reviewer measuring in a fresh clone
+    or a detached worktree — which is exactly where reviewers measure — has no `node_modules` and
+    silently gets the latest release instead of the pinned one. Measured on mosaicstack#1313: the
+    lockfile pins prettier 3.8.1, under which three guides pass; a version-less `npx` in a
+    worktree resolved 3.9.6, under which the same three fail; and 3.0.0, the floor of the declared
+    `^3.0.0` range, fails a different one. Three versions, three verdicts, identical bytes. Use
+    `node_modules/.bin/<tool>`, or name the version the lockfile pins.
+14. **A formatter or linter declared as a range is a dated verdict, not a fact.** If a lockfile
+    pins it, the gate is reproducible today and will disagree with itself the day the pin moves.
+    Report a formatting failure with the version that produced it, always.
+
 ### Feedback Categories

 - **Blocker**: must fix before merge (security, bugs, test failures)