RLOO length-bias A/B ablation, arm0 = sequence_mean loss reduction WITH TIS (truncated importance sampling). Trained with SkyRL (RLOO-n, FSDP2) on DCAgent/exp_rpt_pymethods2test-large from the Qwen3-8B pre-RL base laion/GLM-4_7-swesmith-...-fixthink.

Checkpoint selected at global_step 15 by trailing-5 EMA (alpha=1/3) of reward/avg_raw_reward over the full training chain (cap step <= 80).

Training-time Daytona/Harbor rollouts for this run are uploaded as a companion dataset: open-athena/ablation-pymethods2test-seqmean-arm0-tis

The dataset contains the last episode of each trial (per make_and_upload_trace_dataset --episodes last) — the same rollouts the policy was trained on after rollback / truncation.