{"type":"post","id":"how-meta-catches-bugs-before-code-ships-9-e2fbb9","slug":"how-meta-catches-bugs-before-code-ships-9-e2fbb9","title":"How Meta Catches Bugs Before Code Ships (9 minute read)","description":"Meta says its LLM-powered Just-in-Time Testing system has progressed from a research prototype into production infrastructure.","retrieval_nugget":"Meta says its LLM-powered Just-in-Time Testing system has progressed from a research prototype into production infrastructure. The system generates tests around incoming code changes to catch defects before they land, while treating false-positive control, testing overhead, and human review as operating constraints rather than afterthoughts.","published_at":"2026-10-30","updated_at":"2026-10-30","record_date":"2026-10-30","date_kind":"published_at","topics":["coding-agents","evals"],"entities":["Meta","Catching Just-in-Time Tests","JiTTests","Just-in-Time Catching Test Generation at Meta"],"related_patterns":["verification-bandwidth-is-the-scarce-resource"],"novelty_label":"new_fact","what_changed":"Meta’s production JiTTests system is unrelated to the archived Meta projects and other tools.","prior_refs":[],"source_url":"https://engineering.fb.com/2026/10/29/security/catching-bugs-before-they-land-jittestings-human-on-the-loop-approach-at-full-scale","source_urls":["https://engineering.fb.com/2026/10/29/security/catching-bugs-before-they-land-jittestings-human-on-the-loop-approach-at-full-scale"],"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:how-meta-catches-bugs-before-code-ships-9-e2fbb9","status":"published","visuals":[],"editor":{"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]},"routes":{"html":"https://newruntime.com/posts/how-meta-catches-bugs-before-code-ships-9-e2fbb9/","markdown":"https://newruntime.com/posts/how-meta-catches-bugs-before-code-ships-9-e2fbb9.md","json":"https://newruntime.com/posts/how-meta-catches-bugs-before-code-ships-9-e2fbb9.json"},"next_reads":[{"type":"topic","path":"/topics/coding-agents/","url":"https://newruntime.com/topics/coding-agents/","title":"Coding Agents","reason":"Explore the coding-agents topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/coding-agents.md","json_url":"https://newruntime.com/topics/coding-agents.json"},{"type":"topic","path":"/topics/evals/","url":"https://newruntime.com/topics/evals/","title":"Evals","reason":"Explore the evals topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/evals.md","json_url":"https://newruntime.com/topics/evals.json"},{"type":"collection","path":"/posts/","url":"https://newruntime.com/posts/","title":"Field Notes","reason":"Open the latest editorial analysis.","media_type":"text/html","json_url":"https://newruntime.com/posts.json"},{"type":"collection","path":"/source-ledger.json","url":"https://newruntime.com/source-ledger.json","title":"Source Ledger","reason":"Inspect the public source evidence graph.","media_type":"application/json"}]}