exp006_sd15core_relay/README.md

# exp006_sd15core_relay — relays on the CORE EPRED SD1.5 (CANDIDATE, s0)

**Question.** Does the relay recipe certify on the primary substrate — stock
`stable-diffusion-v1-5`, epsilon objective on the shipped schedule, natural
77-token plain-English conditioning — and does it beat matched LoRA there?

**Design.** exp001's design transplanted to the natural paradigm: frozen fp32
stock UNet; three arms on one shared cache (4096/256 rows, latents + nl77
conditioning); epsilon-prediction loss with the stock scaled-linear schedule,
t~U{0..999}, 10% CFG dropout; 3000 steps, batch 16, pure Adam wd=0, gradient
checkpointing; paired val on FIXED per-row (noise, t), fp32. Round-trip judge
via the standard StableDiffusionPipeline (stock scheduler) on exp000's rows,
read against exp000b's `sd15_epred_core` baseline row (+0.1809).

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

| arm | trainable | val eps-MSE | Δ vs frozen | round-trip gap |
|---|---|---|---|---|
| frozen | 0 | 0.124788 | — | (+0.1809 baseline) |
| **relay_all16** | 3,227,568 | **0.121698** | **−2.5%** | **+0.2172** |
| lora_r32 | 3,182,592 | 0.122674 | −1.7% | +0.1596 |

**Findings (candidate, s0).**
1. **Relay ≥ matched LoRA, 2-for-2 across substrates** (here and exp001 on
   the Lune flow trunk). On the core, LoRA does help val (unlike Lune where
   it landed below frozen) — but stays behind the relay.
2. **Grounding: relay gains, LoRA trades away.** The relay arm *improved*
   natural-prompt round-trip grounding over the zero-shot core baseline
   (+0.1809 → +0.2172) while LoRA degraded it (+0.1596). Same direction as
   exp001; stronger effect.
3. **Gate dynamics are substrate-dependent:** core-epred relay gates GREW
   (0.0474 init → mean 0.0700, max 0.0986 — the "trunk opts in" mechanism
   from the text line), where Lune relay gates shrank (exp001, mean 0.0432).
   Neither sits in the LM-line 0.012–0.03 band.
4. **Toggle law held post-train, bit-exact** (toggled-off val ≡ frozen).

**Caveats.** Single seed; 3k-step short-train (machinery certification, not a
capability claim); one LoRA placement/rank; round-trip n=24. Cost ≈ 3.1 GPU-h.
Checkpoints: `relay_all16_s0.pt`, LoRA in the run dir (ships on request —
the relay stack is the line's artifact).

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## SEED-1 REPLICATION (2026-07-17, `results_s1.json`) — PROMOTED TO 2-SEED CONFIRMED
Same cache/val; training stochasticity reseeded. relay 0.121709 (s0 0.121698),
lora 0.122673 (s0 0.122674), frozen identical. Relay beats frozen AND matched
LoRA in BOTH seeds; round-trip relay +0.2206 (s0 +0.2172) vs lora +0.1889
(s0 +0.1596); gate growth replicates (mean 0.0707 vs 0.0700). No seed lottery.
Scope: 2 training seeds on one shared cache; data reseeding untested.