llms.txt: inspect a voluntary page reference

GET /llms.txt distinguishes 200, 404/410 and retrieval unknown. A bounded leading HTML-document pattern is reported. A conservative standalone/list inline Markdown subset supplies up to eight distinct URL status checks. Exact URL duplicates and count/heading patterns are observations.

This is not general Markdown validation, complete link checking or a consumer-compatibility test. Unsupported syntax can suppress actionable entries. A redirect, protected endpoint or intentionally retired URL needs context. Absence is optional, not a universal defect.

If you maintain this file for a known consumer, inspect its actual response and intended source pages. Review 404/410 on the exact checked URL before changing an entry. Do not create a file just to earn a legacy score.

- [Reference](https://example.com/reference): API reference

This standalone entry is within the supported subset. A 200 status verifies only the bounded status response, not correct documentation content or AI use.

Public measurement separates Confirmed issue, Advisory, Unknown, Not applicable and Observed pass. An observed pass applies only to an explicit bounded rule; absence of an emitted failure is not a pass. Missing prerequisites do not earn repair credit.

Start 100. Retrieval unknown returns 0; absent/empty returns 100; leading HTML pattern returns 10. Subtract min(40, 10 × sampled 404/410 count) and min(15, 5 × redirect count). Other observations do not deduct.

Legacy values are clamped to 0..100 and rounded. They are not readiness certification, risk indicators or predicted citation outcomes. Method changes do not rewrite historical records.

The observations above describe the local implementation, not guarantees from these sources. Protocol and provider documents help interpret purpose and perform checks this audit does not implement.

• llms.txt proposal (voluntary convention)