# L5-N541 adjacent-layer branching bundle

This bundle accompanies the Mesocosm writeup **When the Threads Branch**.

## Protocol

- GPT-2 Small, Hugging Face revision `607a30d783dfa663caf39e06633721c8d4cfcd7e`
- float32, TF32 disabled, deterministic CUDA configuration
- implicit resonance (`imp_r`): BOS plus all ordinary input tokens
- post-GELU MLP activations
- sentence destination: largest neuron activation observed across all token positions
- local intervention: set L5-N541 to zero at its natural peak position

## Files

- `probe_541_to_l6.py` — reduced 80-row and 62-exact-unique replay/ablation.
- `trace_541_full_to_l6.py` — full-sentence peak-position trace and local ablation for the 80 natural Moby Dick L5-N541 routes.
- `probe_541_l6_branch_panel.py` — preregistered 24-positive/24-control held-out panel.
- `541 MAE List - Moby Dick.txt` — reduced-string source packet.
- `n541_l5_to_l6_ablation_all_80.csv` — reduced 80-row result.
- `n541_l5_to_l6_ablation_unique_62.csv` — exact-unique result; primary reduced-string summary.
- `n541_full_80_l5_l6_peak_trace.csv` — full-sentence peak trace.
- `n541_l6_held_out_branch_panel.csv` — held-out panel result.

## Full-corpus inputs

The full-sentence tracer additionally reads aligned L5 and L6 destination exports for 7,353 Moby Dick sentences. These large source exports are not duplicated in this small bundle. Their expected filenames are:

- `the_sea_implicit_resonance.json`
- `the_sea_implicit_resonance_L6.json`

The copy of `trace_541_full_to_l6.py` is the exact script used for the reported run and therefore retains its original local input paths. To reproduce elsewhere, change `L5_FILE` and `L6_FILE` to the locations of the aligned exports.

## Reading the evidence

The outputs support differently signed, graded effects from L5-N541 onto several L6 neurons at construction completion. They do not establish labelled semantic channels, dedicated circuit edges, or one-to-one neuron meanings. Keep the 62-string exact-unique result separate from the duplicate-weighted 80-row result.