Remediation
<html lang> matches the language the visible content is actually written in, per a conservative deterministic language profile. The classic failure is a template default nobody edited: a German shop declaring lang="en". A mismatch WARNs, never fails - the detector is probabilistic and stays silent when unsure.
coherence.language_declared_matches_contentreadabilityweight 1heuristic
Why it matters
<html lang> matches the language the visible content is actually written in, per a conservative deterministic language profile. The classic failure is a template default nobody edited: a German shop declaring lang="en". A mismatch WARNs, never fails - the detector is probabilistic and stays silent when unsure.
How to fix
- See the full check definition in the rubric (linked above) for the canonical reference.
- Reach out to research@agentspeed.com if you need clarification on the check.
Hand it to your AI assistant
Paste this into Claude Code, Cursor, or any assistant with your repository open. It carries the steps, how to verify them, and the shortcuts to avoid. It is generic, though: run a scan to get one written from what your pages actually do.
Run a scan to check your site
Verify on your site
Run a scan against your domain to see whether coherence.language_declared_matches_content currently passes, warns, or fails. Free, no signup; the score page is permanent and citable.