# exp010_controller — THE STEP-GATED DIFFUSION CONTROLLER + generation-side
# band-lesion battery (CANDIDATE, 1-seed battery)

**The artifact.** `StepGatedSampler` — DDIM sampling where EVERY denoising
step sets the band crossfade windows from the current timestep, activating
the trained band experts coarse-to-fine across the trajectory. The stage's
controller, shipped as a usable module.

**The question.** exp009 showed per-step eps-MSE is nearly blind to band
behavior (0.05–0.2% moves). What do the bands do IN IMAGE SPACE? Battery:
exp008's 2-seed-confirmed mb3 stack; arms all_on / lesion each band / frozen;
paired seeds; judged by round-trip grounding, lesion-vs-all_on LP/HP
decomposition, and within-prompt diversity (6 prompts × 4 seeds).

**Results** (`results.json`):

| arm | grounding gap | diversity | LP-change vs all_on | HP-change |
|---|---|---|---|---|
| **all_on** | **+0.2135** | 0.196 | — | — |
| lesion band0 (LOW noise) | +0.1979 | 0.208 | 0.0036 | 0.0031 |
| lesion band1 (MID) | +0.1821 | 0.217 | 0.0184 | 0.0039 |
| lesion band2 (HIGH noise) | +0.1782 | 0.297 | **0.0727** | 0.0051 |
| frozen | +0.1247 | 0.332 | 0.0804 | 0.0052 |

**Findings.**
1. **The controller lifts grounding +0.089 over frozen** (+0.1247 → +0.2135)
   and every band lesion cuts it monotonically — all three bands carry
   generation-relevant signal that eps-MSE could not see. The image-space
   instrument was the right upgrade.
2. **Coarse-to-fine confirmed by lesion signature ratios**: the HIGH-band
   lesion is 14× LP-dominated (0.0727 LP vs 0.0051 HP — structure/layout),
   the LOW-band lesion is ~1:1 detail-leaning (0.0036/0.0031), MID
   intermediate. (Raw prereg G2b "LOW moves HP most in absolute terms"
   missed — layout shift mechanically drags detail with it; the per-lesion
   ratio is the honest read, disclosed.)
3. **Diversity interpretation flip (G3 miss, informative):** the eps-trained
   HIGH band CONCENTRATES generations toward the conditioning (its lesion
   raises diversity 0.196 → 0.297; frozen is most "diverse" because least
   grounded). A diversity-CARRYING high-noise expert remains a training-
   objective goal (nothing here trained for diversity), not a refuted
   property — the docket's diversity/blob supervision is the open path.

**Caveats.** 1-seed battery (one noise-seed bank, n=24 + 6×4 diversity
probe); one checkpoint (uniform-trained mb3_s0; the roles checkpoint runs
the same battery as an amendment); CLIP-L gauges. Cost ≈ 0.2 GPU-h.

---
## AMENDMENT: the ROLES checkpoint through the same battery (`results_roles_s0.json`)
Image-space lesion signatures are IDENTICAL to the uniform checkpoint's
(band2 LP-change 0.0724 vs 0.0727; all bands within a few %), and role
training slightly COST grounding (all_on +0.1996 vs uniform +0.2135).
Frequency-reweighted role pressure is now confirmed inert on BOTH
instruments (per-step gauges, exp009; generation-side battery, here).
The role thesis's open path is qualitatively different supervision
(segmentation blobbing / diversity pressure — the stage's exp011+).