What problem does it solve? Final-answer scoring hides where an agent actually went wrong: a trace can reach a correct answer via a bad path, or fail only at the last step after a good run. This Skill scores the trajectory itself and pinpoints the first step where a failed trace diverged from a known-good path. ## Core Features & Use Cases - Three independent code-based checks: pytest-style evaluators over evallib.schema.Trace for tool selection, argument-schema validity, and execution success, each reported separately. - Transition failure matrix: uses scripts/transitions.py to extract per-turn state sequences, build transition counts, and compute each failed trace's earliest divergence index against a reference sequence. - Divergence-ranked reporting: outputs transition_matrix.json and divergence_report.json, ranking which state most often marks the first failure point, cross-referenced against an existing failure taxonomy backlog. - Use Case: After running an agent over evals/traces.jsonl, discover that 12 of 20 failed refund traces first diverge at tool_call:issue_refund because eligibility was never checked — and fix that step first. ## Quick Start Evaluate the traces in evals/traces.jsonl for tool selection, argument validity, and execution success, then build a divergence report showing where failed traces first went wrong.