feat: respect robots.txt before fetching pages#8
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Production-grade crawlers check robots.txt. deepdive's per-query fetch volume is low (~12 URLs) but it's still the polite thing; sites with explicit scraper deny rules shouldn't be surprised. Behavior: - Before every agent.fetchOne, we check <scheme>://<host>/robots.txt with User-Agent "deepdive-bot" (configurable via AgentConfig.robotsUserAgent). - On "deny", skip the URL + emit a new fetch.skipped event so --verbose output shows the skip reason. - On "allow" or "unknown", proceed as before. - robots.txt content is cached in-memory per run (one GET per origin). - Network errors fetching robots.txt err on the side of "fetch" rather than "deny" — publishers who care have working robots.txt. Opt-out: --ignore-robots / DEEPDIVE_IGNORE_ROBOTS=1 bypasses the check entirely (for operators with their own relationship to the target). Parser supports: User-agent blocks (case-insensitive substring match, exact agent beats *), Disallow + Allow with longest-prefix wins (ties go to Allow per RFC 9309), empty Disallow = allow everything, wildcard * in paths, $ end-anchor, Crawl-delay field, # comments. Tests: 17 new assertions (12 parser unit, 5 canFetch integration, 2 CLI). 198 total.
This was referenced Apr 23, 2026
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Summary
Production-grade crawlers check robots.txt. deepdive's per-query fetch volume is low (~12 URLs) but it's still the polite thing; sites with explicit scraper deny rules shouldn't be surprised.
Behavior
Before every
agent.fetchOne, check<scheme>://<host>/robots.txtwith User-Agentdeepdive-bot:fetch.skippedeventunknown(err on the side of fetching; publishers who care have working robots.txt)robots.txt content is cached in-memory per run (one GET per origin).
Opt-out
--ignore-robots/DEEPDIVE_IGNORE_ROBOTS=1bypasses entirely — for operators with their own relationship to the target.Parser
*)Disallow+Allowwith longest-prefix wins, ties go to Allow (RFC 9309)Disallow:grants everything*in paths,$end-anchorCrawl-delayfield captured (not yet enforced — would need per-host pacing in the fetch worker-pool)#comments strippedNew library exports
canFetch,createRobotsCache,parseRobotsTxt,isPathAllowed,DEFAULT_USER_AGENT, and typesRobotsCache,ParsedRobots,RobotsCheckResult,CanFetchOptions.Test plan
npm run build— clean under strict: truenpm test— 181 pass (up from 164), 0 fail*, UA substring+case-insensitive, comments, empty-Disallow grants, wildcard+$patterns, Crawl-delay captured, malformed lines skipped