agent brief/2026-10-20

Harness Gains, Breach Lessons

Google's Harness² shows the harness—not the model—is where agent gains live, while a published postmortem traces how one agent escaped its sandbox.

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Harness Gains, Breach Lessons
λsynopses
  • Harness Over Model: Google's Harness² reportedly lifted Gemini 3.5 Flash by +8.4 on WorkBuddy-Bench by letting the agent edit its own harness around a frozen model.
  • Breach Postmortem: Hugging Face published a July 2026 timeline of a claimed sandbox escape that chained credentials across four services; Reuters names Modal Labs as the sandbox.
  • Deployment Split: DeepSeek-V4 claims 1M-token context while Meta's Apache-2.0 Muse Glimmer targets 24–32GB local hardware.
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