--- title: Frontier Code (GPT-5.6 VS Mythos): This BENCHMARK is... description: Cognition's Frontier Code benchmark evaluates AI coding agents on code mergeability rather than just test passage. It uses 150 tasks (with a hardest 50... canonical: https://daily.dev/posts/frontier-code-gpt-5-6-vs-mythos-this-benchmark-is-actually-real--d9rhz6s9h twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Frontier Code (GPT-5.6 VS Mythos): This BENCHMARK is ACTUALLY REAL! | daily.dev og:description: Cognition's Frontier Code benchmark evaluates AI coding agents on code mergeability rather than just test passage. It uses 150 tasks (with a hardest 50... og:url: https://daily.dev/posts/frontier-code-gpt-5-6-vs-mythos-this-benchmark-is-actually-real--d9rhz6s9h og:image: https://api.daily.dev/og/posts/D9rHz6S9H.png og:image:alt: Frontier Code (GPT-5.6 VS Mythos): This BENCHMARK is ACTUALLY REAL! og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Frontier Code (GPT-5.6 VS Mythos): This BENCHMARK is ACTUALLY REAL! **[AICodeKing](https://daily.dev/sources/aicodeking)** · 16 min read · 0 upvotes · 0 comments ## Summary Cognition's Frontier Code benchmark evaluates AI coding agents on code mergeability rather than just test passage. It uses 150 tasks (with a hardest 50 'Diamond' subset) sourced from 36 open source repos, graded by actual maintainers across axes like behavioral correctness, regression safety, scope, and code quality. Results show Claude Opus 4.8 leads on Diamond with only 13.4% score, highlighting how far current models are from production-quality code. The benchmark also compares favorably to older benchmarks like SWE-Bench Pro on false positive rates (81% reduction). Key caveats: tasks are not public, scores reflect model+harness combinations, and prompt-based grading introduces subjectivity. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#llm](https://daily.dev/tags/llm), [#code-review](https://daily.dev/tags/code-review) [View this post on daily.dev](https://daily.dev/posts/frontier-code-gpt-5-6-vs-mythos-this-benchmark-is-actually-real--d9rhz6s9h) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Frontier Code (GPT-5.6 VS Mythos): This BENCHMARK is ACTUALLY REAL!","url":"https://daily.dev/posts/frontier-code-gpt-5-6-vs-mythos-this-benchmark-is-actually-real--d9rhz6s9h","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/frontier-code-gpt-5-6-vs-mythos-this-benchmark-is-actually-real--d9rhz6s9h"},"datePublished":"2026-06-09T09:41:11.109Z","dateModified":"2026-06-15T12:01:11.942Z","description":"Cognition's Frontier Code benchmark evaluates AI coding agents on code mergeability rather than just test passage. 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