{"ok":true,"kind":"crawlcheck-rulebook","v":1,"generated_at":"2026-10-07T17:45:14.108Z","score_version":28,"schema":"https://crawlcheck.io/schemas/rulebook.json","counts":{"rules":77,"by_kind":{"scan":52,"answer_correlation":5,"capability_mismatch":6,"self_audit":12,"mcp_server":2},"by_family":{"site":8,"headers":4,"mostly_code":3,"machine_files":11,"robots":13,"delivery":8,"jsonld":3,"nap":2,"answers":5,"capabilities":6,"self_audit":12,"mcp":1,"watch":1},"revised":7,"scored":48},"scans_counted":3137,"severity_scale":[{"level":"info"},{"level":"low"},{"level":"medium"},{"level":"high"},{"level":"critical"}],"method":{"revisions":"A rule that changes what it reports gets a new revision; a record keeps the revision that decided it, and a replay uses that revision, never today's.","share":"Share of counted scans that carried the code at least once, the same numbers /data publishes. Self-scans and opted-out sites are never counted.","grade":"Each finding has a level from info to critical. Open findings at medium and above lower the letter grade; fix them first."},"rules":[{"code":"CONTENT_NEEDS_JAVASCRIPT","kind":"scan","family":{"id":"mostly_code","label":"Mostly code"},"title":"The page’s content only exists after JavaScript runs","meaning":"The HTML the server sends is an application shell: a framework mount point and a script bundle, with almost no readable text. A browser runs the bundle and the page appears. A crawler that does not execute JavaScript — which is most AI crawlers and every training-data fetch — receives the shell and quotes nothing. This is measured on the bytes the server delivered, not on a rendered view; a framework by itself is not the defect, an empty delivery is.","severity":{"level":"medium"},"scored":true,"measured_on":"full scans only (the daily watch does not measure it)","revision":{"current":1,"revised_at":null},"fix":{"advice":"Render the page on the server or at build time (Next.js/Nuxt/SvelteKit SSR or SSG, or a prerender step) so the delivered HTML already contains the text. Check by fetching the page with curl: the words a crawler needs must be in that response.","effort":"build","endpoint":null},"share_of_scans":{"pct":1.1,"scans":34,"of_scans":3137,"basis":"share of counted scans that carried it; the same numbers /data publishes"},"links":{"self":"https://crawlcheck.io/rules#CONTENT_NEEDS_JAVASCRIPT","api":"https://crawlcheck.io/api/rules?code=CONTENT_NEEDS_JAVASCRIPT","glossary":["https://crawlcheck.io/glossary/render-dependence","https://crawlcheck.io/glossary/render-dependence-gap","https://crawlcheck.io/glossary/render-gap"],"workflow":null,"lineage":"https://crawlcheck.io/docs/lineage-coverage","explain_template":"https://crawlcheck.io/api/explain?id={report_id}&code=CONTENT_NEEDS_JAVASCRIPT"}}],"filter":{"code":"CONTENT_NEEDS_JAVASCRIPT"}}