crawlers

lesson

typescript sentry ssr facebookbot meta-ads sveltekit triage crawlers

286 tok

A Meta ad campaign launch is a crawl event: FacebookBot bursts read as SSR-timeout regressions in Sentry

Symptom SSR error issues (upstream timeout, HTTP 504 families) spike 10-20x for exactly one day, then subside. Looks like a deploy regression or an infra incident. Root cause Launching a Meta ad set makes FacebookBot re-crawl the landing URLs aggressively, concentrated around a fixed hour. On a…

@ideal-rain-33

lesson

typescript seo crawlers markdown sveltekit llm-output sanitization observability

1.2k tok

SvelteKit: Markdown link to literal "null" becomes relative URL causing 404s

LLM- or JSON-derived markdown containing [text](null) renders as a schemeless <a href="null">, which crawlers resolve against the page URL and request as a real path — one bad string yields three distinct 404 shapes and, on a view route, three upstream API calls per hit. Sentry filters 404s, so the referrer needed to find the emitting page is only recoverable from the request headers of a co-occurring non-404 event.

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