memory: ComfyUI API shape, SD's failure on flat swatches, the material-slot collapse

MEMORY.md

@@ -486,3 +486,9 @@ Scope: facts and traps that cost time to establish. Planned work lives in [TODO.
 - **Workaround that works: import under a new name.** `Tools/ue_character_anim_import.py` now uses `PREFIX = "CharacterV2"`, which creates `CharacterV2`, `CharacterV2_Skeleton` and `CharacterV2Human_rig_GigLine_{Idle,Walk}` fresh; the same quaternion probe then returned `(+0.439, +0.898)`, i.e. the 0.55 rad arm rotation had finally landed.
 - **Check the asset, not the importer.** A pose or material change that does not alter the probed asset data did not happen, whatever the log says. Probing a clip's bone quaternion takes one commandlet and settles it in seconds.
 - **The arms-down rotation belongs in the clips, not in the bind.** Every bind experiment (bake pose to rest, clear shape keys, apply the armature modifier, re-bind) was either impossible on this shape-keyed MPFB mesh or left Unreal showing the old bind. `Tools/character_anim_build.py` now carries a measured base offset in the clip keys (`BASE`: 0.55 rad on `upperarm01`, chosen by sweeping the rotation in Blender and reading the bone direction), and the character stands with its arms at its sides.
+
+## 2026-11-09 — Textures: ComfyUI works, Stable Diffusion fails for flat swatches
+
+- **ComfyUI is reachable at `127.0.0.1:8188` (0.44.0)** and its API is the clean way in: `POST /prompt` with an API-format graph (`[node_id, output_index]` references — the UI's workflow JSON cannot be posted), then poll `/history/<id>` and fetch `/view?filename=...`. `Tools/comfyui_generate.py` does this and writes a sidecar with model, prompt, seed and the full graph. Installed checkpoints: `juggernautXL_ragnarok.safetensors`, `epicrealismXL_pureFix.safetensors`, `sd-v1-5-inpainting.ckpt`, plus inpainting variants.
+- **Do not ask Stable Diffusion for a flat texture swatch.** Three attempts at "seamless skin texture" produced an anatomical close-up twice and a leather-scale surface once. SDXL has no reliable notion of a material sample without anatomy, so every seed needs manual rejection — worse than noise we control. Procedural generation won for skin pores (`Tools/generate_character_textures.py`, tileable octave noise) and a strand sheet for hair.
+- **Unreal collapses the second material slot on a skeletal-mesh import.** A joined hair cap (Blender shows two slots, hair faces on index 1) arrives as a single slot named after the body material, so the hair renders with the skin material. `unreal.SkeletalMesh` has no `set_material`, so it cannot be re-slotted after import. A separate skeletal mesh attached as a second component is the way around it.