Microsoft's ActiveSaddler picks training tasks by open failures: +7.5 on Terminal-Bench 2.0

rohanpaul_ai · x · 2026-10-05

A new Microsoft paper introduces ActiveSaddler, an active task-selection method for agent harness optimization. Instead of a fixed task list, it tracks failure patterns and targets the most valuable unfixed failures, or explores unseen tasks to discover new ones. Gains: +4.4 points pass rate on GAIA2 and +7.5 on Terminal-Bench 2.0; reaching 58.5% GAIA2 dev accuracy cost $298 vs $1,360 with fixed ordering. Takeaway: aim your optimizer budget at still-open failures.

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