Claim checker for public texts (TypeSafe), measured manifest load times, corrected README timings

CONTRIBUTING.md

@@ -50,6 +50,23 @@ and 3.13. If your change touches file formats, calling, QC or outputs, also run
 8. **Plain writing.** Documentation follows the voice in `branding/README.md`: short sentences, numbers instead of
    adjectives, and every claim next to its limitation.
 
+## Checking numbers before publishing
+
+Text that quotes results (README, user guide, blog posts, announcements) is checked against the validation reports
+before it goes out:
+
+```bash
+python scripts/docs/check_claims.py README.md blog/*.md docs/user_guide.md my_draft.txt
+```
+
+Code finds every sentence or table row with a number and the passages in `docs/validation/`,
+`docs/known_unknowns.md` and the spec that share it; a TypeSafe System One model only judges whether each passage
+supports, contradicts or says nothing about the claim. `claims_report.md` lists contradicted claims, claims without
+a source, low confidence cases for a person to read, and verified claims. Only this repository's documentation text
+is sent to the API, never data. The key comes from `TYPESAFE_API_KEY` or `~/.config/typesafe/credentials` and never
+enters the repository; a full check costs well under one cent. `--dry-run` shows the claims and evidence without
+calling the API.
+
 ## Pull requests
 
 * One topic per pull request, with tests.