Source Claim Proof Verifier

Use this endpoint when you need to verify whether a specific, already-known source URL actually substantiates a single discrete factual claim — especially for citation auditing, misinformation detection, or fact-checking pipelines where the source is already identified. This is not a web search tool; you must provide both the URL and the exact claim. Prefer this over general fact-checkers when provenance matters and you need snippet-level evidence from a specific page.

• blocked — the target URL returned a 403 or bot-blocking response, so content could not be read
• unreachable — the target URL timed out or returned a 404/5xx error
• unsupported — the URL points to a PDF, video, or non-parseable content type
• insufficient-evidence — the page loads but contains no content clearly related to the claim
• claim too broad or compound — multi-part claims may get ambiguous verdicts; only atomic claims are supported
• URL exceeds 2048 characters or claim is fewer than 3 characters — returns validation error