To verify link liveness, the engine scans the markdown draft for inline and autolinked URLs, probing them concurrently using thread-pooled, ranged streaming GET requests (bytes=0-0) routed through strict SSRF guards. Each response is categorized—marking 4xx, 5xx, or unreachable destinations as broken—and cached in memory to avoid duplicate network calls across drafts. When dead citations are found, the engine unwraps them into plain anchor text to maintain sentence flow without leaving broken hyperlinks, all while strictly shielding the protected target URL so it is flagged for review rather than deleted.