| # Split-Expert Bring-Up (`2026-03-10`) | |
| This bundle captures the initial PyTorch bring-up for the new packed TWIN split-action-expert path on `pi0.5`. | |
| Included here: | |
| - exact split warm-start checkpoints created from the original single-head PyTorch base checkpoint | |
| - invariant-check outputs for `split_independent` and `split_communicating` | |
| - detached real-data smoke and `20`-step training logs on `lsnu/twin_dual_push_128_train` | |
| - reproducibility commands used for the bring-up | |
| ## Warm-start summary | |
| Both split modes inherit the same base expert weights and per-arm input/output projections from the single-head checkpoint. | |
| - `split_independent` | |
| - `left_expert_max_abs_diff = 0.0` | |
| - `right_expert_max_abs_diff = 0.0` | |
| - `left_input_projection_max_abs_diff = 0.0` | |
| - `right_input_projection_max_abs_diff = 0.0` | |
| - `left_output_projection_max_abs_diff = 0.0` | |
| - `right_output_projection_max_abs_diff = 0.0` | |
| - `split_communicating` | |
| - same exact inherited diffs as above | |
| - added cross-arm communication parameters are zero-initialized at warm start | |
| ## Real-data bring-up summary | |
| Dataset used for real-data smoke and short training: | |
| - `lsnu/twin_dual_push_128_train` | |
| Successful detached runs: | |
| - `split_independent_real_smoke3_r2` | |
| - `3` train steps on real packed TWIN data | |
| - checkpoint saved at step `3` | |
| - `split_communicating_real_smoke3` | |
| - `3` train steps on real packed TWIN data | |
| - checkpoint saved at step `3` | |
| - `split_independent_real_train20` | |
| - `20` train steps on real packed TWIN data | |
| - final logged train loss at step `20`: `0.6038` | |
| - checkpoint saved at step `20` | |
| - `split_communicating_real_train20` | |
| - `20` train steps on real packed TWIN data | |
| - final logged train loss at step `20`: `0.5943` | |
| - checkpoint saved at step `20` | |
| ## Layout | |
| - `bootstrap_checkpoints/` | |
| - exact split warm-start checkpoints | |
| - `sanity_checks/` | |
| - invariant-check outputs | |
| - `run_logs/` | |
| - detached real-data run logs | |
| - `repro/commands_bringup.sh` | |
| - reproduction commands used during the bring-up | |