{"type":"post","id":"google-harness2-for-recursive-self-improvement-github-repo-89c90b","slug":"google-harness2-for-recursive-self-improvement-github-repo-89c90b","title":"Google Harness² for Recursive Self Improvement (GitHub Repo)","description":"Harness² makes the harness, rather than the model weights, the object of recursive improvement.","retrieval_nugget":"Harness² makes the harness, rather than the model weights, the object of recursive improvement.","published_at":"2026-10-15","updated_at":"2026-10-15","record_date":"2026-10-15","date_kind":"published_at","topics":["google"],"source_urls":["https://github.com/google-research/harness2"],"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:google-harness2-for-recursive-self-improvement-github-repo-89c90b","status":"published","visuals":[],"editorial_provenance":{"schema_version":"newruntime-editorial-copy-v1","content_status":"source_grounded_final","final_copy_sha256":"sha256:905a7751bb00a39b1cbfff2353849dbaeb04a02c4198dd7ef254f259776219f3","reviewed_at":"2026-10-15T16:09:22.316Z","source_evidence_count":1,"verified_claim_count":3,"site_analysis_schema_version":"newruntime-site-analysis-v1","site_object_kind":"field_note","observed_fact_count":3,"implication_count":2,"watch_condition_count":1,"related_record_count":0},"analysis":{"schema_version":"newruntime-site-analysis-v1","object_kind":"field_note","thesis":"the harness can be refined as an editable, evidence-bearing system around a fixed model.","observed_facts":[{"text":"The repository describes task-level Propose–Probe–Compose refinement without ground-truth feedback, alongside a persistent harness-level loop that retains adopted harnesses and evidence-supported lessons.","source_urls":["https://github.com/google-research/harness2"]},{"text":"It lists eight editable components: system prompt, guardrails, memory, tool guidance, subagents, skills, scripts, and plugins.","source_urls":["https://github.com/google-research/harness2"]},{"text":"Google reports maxima of 11.5 points on WorkBuddy-Bench, 4.5 on JobBench, and 11.8 percentage points in LAB partial pass rate.","source_urls":["https://github.com/google-research/harness2"]}],"mechanism":"An agent proposes harness edits, probes their effects on the same task, and composes a refinement from behavioral contrasts; adopted harnesses and evidence-supported lessons can then guide subsequent task-level refinement.","why_now":"the release turns harness engineering from an abstract practice into a runnable, benchmarked workflow for recursive refinement.","implications":["Teams can treat harness changes and their evidence as a persistent engineering asset, while holding model weights fixed.","The two loops separate local adaptation for a task from retained learning intended to inform future tasks."],"evidence_boundary":"the supplied repository describes the method and reports its own benchmark results; independent replication and broader deployment outcomes are not established here.","watch_conditions":["independent runs should test whether gains persist on unseen tasks and across different model–harness configurations."],"related_records":[],"new_branch_reason":"No prior New Runtime record was supplied; this release's linked task-level and persistent harness-improvement loops warrant a distinct analytical record."},"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/google-harness2-for-recursive-self-improvement-github-repo-89c90b/","markdown":"https://newruntime.com/posts/google-harness2-for-recursive-self-improvement-github-repo-89c90b.md","json":"https://newruntime.com/posts/google-harness2-for-recursive-self-improvement-github-repo-89c90b.json"},"related_patterns":["harness-architecture-outlives-model-choice"],"next_reads":[{"type":"topic","path":"/topics/google/","url":"https://newruntime.com/topics/google/","title":"Google","reason":"Explore the google topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/google.md","json_url":"https://newruntime.com/topics/google.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"}]}