Debug agent failures by finding the earliest error, not the final one — 486 annotated failed trajectories now available as a benchmark

arXiv 2608.06346·medium signalXBlueskyLinkedInCopy link

TrajDebug (arXiv 2608.06346, Aug 6) formalizes long-horizon agent debugging as locating the first error in a failed trajectory and tracing its lifecycle to terminal impact, using multi-granularity history compression plus evidence-based identification rather than reading the whole trace. The authors release TrajErrBench, 486 manually annotated failed trajectories drawn from Tau2Bench (tool use) and SWE-Bench Pro (coding), and report best overall attribution performance against existing baselines. For builders, the release is the asset: a labeled corpus of real agent failure trajectories you can use to evaluate your own post-mortem tooling instead of eyeballing transcripts.