README.md

# ComfyUI-RH-MiniMax-H3

[Chinese documentation](README_CN.md)

RunningHub MiniMax-H3 audio-video diffusion nodes for ComfyUI. The plugin runs
every model component inside the ComfyUI process; it does not call an SGLang
server or a Diffusers pipeline.

The task-aware path exposes T2VA, FL2VA (first/last-frame-to-video+audio), and
Ref2VA (ordered image/audio/video references). All three paths have passed
local contract, packing, sampler, media-preprocessing, static-node, and unit
validation. Ref2VA has also completed a real CUDA end-to-end run with released
weights. FL2VA shares the same FL2VA partition and encoding/sampling contract;
treat a first local CUDA smoke as recommended before production use.

## Install

```bash
cd ComfyUI/custom_nodes
git clone https://github.com/HM-RunningHub/ComfyUI_RH_MinMaxH3.git
pip install -r ComfyUI_RH_MinMaxH3/requirements.txt
```

Restart ComfyUI afterwards: node definitions are read once at start-up.

## Nodes

Every node is registered under an `RHMiniMaxH3` prefix and grouped below the
`RunningHub/MiniMax H3` category. The **node ID** is what a saved workflow
stores as `class_type` / `type`; the **display name** is what the canvas shows.

**`RunningHub/MiniMax H3/loaders`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3DirectModelLoader` | RunningHub MiniMax H3 Model Loader (Direct) |
| `RHMiniMaxH3DirectTextEncoderLoader` | RunningHub MiniMax H3 Qwen3-VL Loader (Direct) |
| `RHMiniMaxH3DirectVAELoader` | RunningHub MiniMax H3 Dual VAE Loader (Direct) |
| `RHMiniMaxH3FL2VAModelLoader` | RunningHub MiniMax H3 FL2VA Model Loader (Direct) |
| `RHMiniMaxH3FL2VATextEncoderLoader` | RunningHub MiniMax H3 FL2VA Qwen3-VL Loader (Direct) |
| `RHMiniMaxH3FL2VAVAELoader` | RunningHub MiniMax H3 FL2VA Dual VAE Loader (Direct) |
| `RHMiniMaxH3Ref2VAModelLoader` | RunningHub MiniMax H3 Ref2VA Model Loader (Direct) |
| `RHMiniMaxH3Ref2VATextEncoderLoader` | RunningHub MiniMax H3 Ref2VA Qwen3-VL Loader (Direct) |
| `RHMiniMaxH3Ref2VAVAELoader` | RunningHub MiniMax H3 Ref2VA Dual VAE Loader (Direct) |

**`RunningHub/MiniMax H3/conditioning`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3T2VATarget` | RunningHub MiniMax H3 T2VA Target |
| `RHMiniMaxH3T2VATextEncode` | RunningHub MiniMax H3 T2VA Text Encode |
| `RHMiniMaxH3UnsupportedConditioning` | RunningHub MiniMax H3 Legacy Unsupported Conditioning (Migration Error) |

**`RunningHub/MiniMax H3/fl2va`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3FL2VAFirstFrameCondition` | RunningHub MiniMax H3 FL2VA First / First+Last |
| `RHMiniMaxH3FL2VALastFrameCondition` | RunningHub MiniMax H3 FL2VA Last Only |
| `RHMiniMaxH3FL2VATarget` | RunningHub MiniMax H3 FL2VA Target |
| `RHMiniMaxH3FL2VAEncode` | RunningHub MiniMax H3 FL2VA Encode |

**`RunningHub/MiniMax H3/ref2va`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3Ref2VAImageReference` | RunningHub MiniMax H3 Ref2VA Image Reference |
| `RHMiniMaxH3Ref2VAAudioReference` | RunningHub MiniMax H3 Ref2VA Audio Reference |
| `RHMiniMaxH3Ref2VAVideoReference` | RunningHub MiniMax H3 Ref2VA Video Reference |
| `RHMiniMaxH3Ref2VATarget` | RunningHub MiniMax H3 Ref2VA Target |
| `RHMiniMaxH3Ref2VAEncode` | RunningHub MiniMax H3 Ref2VA Encode |

**`RunningHub/MiniMax H3/latent`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3EmptyAVLatent` | RunningHub MiniMax H3 Empty AV Latent |
| `RHMiniMaxH3SeparateAVLatent` | RunningHub MiniMax H3 Separate AV Latent |
| `RHMiniMaxH3CombineAVLatent` | RunningHub MiniMax H3 Combine AV Latent |
| `RHMiniMaxH3EncodeVideoAVLatent` | RunningHub MiniMax H3 Encode Video → AV Latent |

**`RunningHub/MiniMax H3/sampling`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3FrameRate` | RunningHub MiniMax H3 Frame Rate (Experimental) |
| `RHMiniMaxH3DualSigmaSampler` | RunningHub MiniMax H3 Dual Sigma Sampler |

**`RunningHub/MiniMax H3/decode`**

| Node ID | Display name |
|---|---|
| `RHMiniMaxH3DecodeAV` | RunningHub MiniMax H3 Decode Video + Audio |

### Migrating older workflows

Node IDs gained an `RH` prefix and the dual VAE loader's `vae_path` became two
inputs, so workflows saved earlier fail with `Node type not found`. Convert them
instead of rebuilding by hand:

```bash
python3 tools/migrate_workflow.py old_workflow.json --in-place
```

Both the frontend graph and the API prompt format are supported. The tool
rewrites node IDs, splits the VAE input, pads widgets to the current signature,
and replaces model names that are no longer selectable with the current default
— every substitution is printed for review. `--in-place` keeps a `.bak`.

## Requirements

- ComfyUI 0.27 or newer (0.28+ recommended)
- A CUDA build of PyTorch compatible with ComfyUI, plus Triton and
  `comfy-kitchen`
- `ffmpeg` and `ffprobe` on `PATH` for Ref2VA video/audio references
  (Ref2VA Encode / Video Reference probe at node-load time; missing tools
  warn early and fail closed when a media plan actually runs)
- MiniMax-H3 weights downloaded separately; weights are not bundled here
- Python dependencies from `requirements.txt`
  (`transformers>=4.57.0,<=5.8.1`)

The runtime is large. INT8 reduces checkpoint storage and transfer cost, but
does not make MiniMax-H3 a small model. BF16 DiT layerwise offload is **auto**
(official `auto_dit_layerwise_offload`, baseline single-GPU 24GB): when free
VRAM ≥ full weights + `DIT_INFERENCE_RESERVE`, layerwise turns off and the DiT
fully resides; otherwise non-block modules stay on GPU and transformer blocks
are prefetched one layer at a time (`ENABLE_DIT_LAYERWISE_OFFLOAD` — `False`
forces full load — / `DIT_LAYERWISE_PREFETCH` in
`minimax_h3_nodes/runtime/h3_settings.py`). INT8 can still use Comfy
MixedPrecisionOps partial/streaming offload. Both paths need substantial host
RAM and fast storage.

Sampler hot-path opts are on by default (toggle independently in
`h3_settings.py` for rollback): `OPT_SDPA_PRECOMPUTED_BOUNDS` (precomputed
attention bounds, no per-layer CUDA→CPU sync), `OPT_PREPARED_STRUCTURE`
(session-cached RoPE/structure tensors), `OPT_INPLACE_EULER_UPDATE` (in-place
target-row updates, no full-row clone), `OPT_ADALN_SEGMENT_BROADCAST`
(segment-wise in-place adaLN broadcast instead of per-layer full-sequence
`index_select`), `OPT_ADALN_PRECOMPUTE` / `OPT_ADALN_RELEASE_WEIGHTS`
(precompute all schedule AdaLN rows once, then drop ~40% of DiT weights;
cache placement via `OPT_ADALN_CACHE_DEVICE`: `auto`/`ram`/`vram`),
`OPT_PREBUILT_TIMESTEPS` (contiguous sigma/timestep
tensors), `OPT_DYNAMIC_ACTIVATION_RESERVE` (shape-aware
activation reserve with `full`/`layerwise`/`partial`/`reject` tiers; sampler
output includes `residency_mode`).

Lifecycle/cache flags (all in `h3_settings.py`):
- `OPT_RESIDENCY_LEASE` + `RESIDENCY_POLICY` (`safe`/`balanced`/`resident`):
  keep DiT warm after inference (`gpu-resident` / `layerwise-warm`) with TTL;
- `OPT_ENCODE_CACHE`: LRU for text prompt, multimodal Qwen, and VAE condition rows (CPU, byte-capped);
- `OPT_VAE_RESIDENCY`: skip `soft_empty_cache` after VAE offload for faster reload;
- `FORCE_ABSOLUTE_MODEL_ROOTS`: `True` forces absolute roots in the COMBO;
  the default `False` follows ComfyUI's directory-model convention and lists names
  relative to each search path (`MiniMax-H3`), resolving through the
  `folder_paths` search order;
- `OPT_WRITE_SIDECAR`: Decode writes JSON under Comfy `output/` (task/geometry/residency/telemetry + `env`: plugin commit / GPU / torch / Comfy);
- Downscale chain for 16:9: `1344x768→1024x576→832x480→640x352`
  (`runtime/downscale.py`).

Packaging (public node class names unchanged):
- `nodes.py` → thin facade; impl in `api/{loaders,targets,conditioning,sampling_nodes,decode,_shared}.py`
- `contracts/` → `constants` / `target` / `conditioning` / `components` / `fingerprints` (+ `_impl`)
- `sampling.py` → `runtime/sampler_core.py`
- `runtime/packing/` · `qwen_encoder/` · `media_conditioning/` · `model_loader/` · `vae_adapter/` · `components/` · `dit/`
- DiT helpers: `runtime/attention.py`, `runtime/prepared_structure.py`

## Telemetry & baseline

- `OPT_TELEMETRY`: stage timers, per-step P50/P95, peak VRAM; sidecar includes `telemetry`
- 24GB primary matrix: `benchmarks/matrix.json` + `benchmarks/BASELINE_24GB.md`
- Aggregate: `python3 benchmarks/run_matrix.py --sidecars <Comfy output> --out benchmarks/results`
- Latent golden: `python3 benchmarks/compare_golden.py --ref a.pt --cand b.pt` (`accel=off`)

## Model layout

Weights live in two places: the **official sharded release** stays under
`ComfyUI/models/diffusers` (or `models/minimax_h3`), while **single-file
conversion artifacts** go into the dedicated root `ComfyUI/models/MiniMax-H3`.

```text
models/MiniMax-H3/                              # flat single-file weights
├── MiniMax-H3-FL2VA-int8_convrot.safetensors
├── MiniMax-H3-Ref2VA-int8_convrot.safetensors
├── qwen3-vl-32b-int8_convrot.safetensors
├── MiniMax-H3-video_vae.safetensors
└── MiniMax-H3-audio_vae.safetensors

models/diffusers/MiniMax-H3/                    # official sharded release
├── FL2VA/
│   ├── transformer/                  # official BF16 DiT (sharded)
│   ├── text_encoder/                 # official Qwen3-VL + tokenizer/processor
│   ├── video_vae/
│   └── audio_vae/
└── Ref2VA/
    └── ...                           # the same component layout
```

The dedicated root holds **weights only, with no sidecar**: component type and
partition are decided entirely by the filename (`MiniMax-H3-<partition>-<format>`,
`qwen3-vl-32b-*`, `MiniMax-H3-{video,audio}_vae`), and a file that does not
follow the convention is ignored rather than guessed at. `config.json`,
`source/config.json`, the tokenizer and `preprocessor_config.json` are still read
from the sharded release that `model_root` points at, so **both locations are
required**: the release supplies the architecture, the dedicated root the tensors.

`model_root` selects the official release. FL2VA nodes only resolve the `FL2VA`
partition; Ref2VA nodes only resolve the `Ref2VA` partition. Each task has three
explicit component loaders and **every dropdown lists only its own component
type**:

- `... Model Loader (Direct)`: `transformer_path` lists DiT weights only,
  filtered by partition.
- `... Qwen3-VL Loader (Direct)`: `text_encoder_path` lists text/multimodal
  encoders only.
- `... Dual VAE Loader (Direct)`: split into `video_vae_path` and
  `audio_vae_path`, selecting and loading the 24-channel video VAE and the
  32-channel audio VAE together.

The selectors never silently switch between BF16 and INT8. Prefer weight
filenames / logical names, for example:

- DiT INT8 (single file): `MiniMax-H3-FL2VA-int8_convrot.safetensors` /
  `MiniMax-H3-Ref2VA-int8_convrot.safetensors`
- DiT BF16 (sharded): logical name `MiniMax-H3-FL2VA` / `MiniMax-H3-Ref2VA`
- TE INT8 (single file): `qwen3-vl-32b-int8_convrot.safetensors`
- TE BF16 (sharded): logical name `qwen3-vl-32b`
- VAE single file: `MiniMax-H3-video_vae.safetensors` /
  `MiniMax-H3-audio_vae.safetensors`
- VAE sharded/original: logical name `MiniMax-H3-video_vae` /
  `MiniMax-H3-audio_vae`

A flat single file carries no `quant_meta.json`, so **the filename is the
partition proof**: feeding a Ref2VA DiT into an FL2VA node fails closed. The
selected weight path is folded into the component fingerprint, so swapping a
checkpoint is detected downstream.

Legacy directory names such as `transformer_int8_convrot` / `vae`, and merged
dual-VAE bundles inside a release, still resolve for older workflows. The old
single `vae_path` input has been replaced by `video_vae_path` +
`audio_vae_path`, so existing workflows containing a VAE loader must reconnect
that node.

Loading the Qwen processor validates the official
`preprocessor_config.json` / `video_preprocessor_config.json` (shortest/longest
edge, patch/merge, mean/std). Generic Qwen3-VL processors or wrong hardcoded
pixel caps fail closed so conditioning embeddings cannot silently drift.

## FL2VA workflow

The supported keyframe signatures are first frame, last frame, or first+last
frame. Conditions and their semantic frame positions are carried together and
validated again before sampling.

1. Load an image with ComfyUI `LoadImage`.
2. Build `RunningHub MiniMax H3 FL2VA First / First+Last` (or `Last Only`).
3. Load FL2VA DiT, Qwen3-VL, and VAE with the three FL2VA loaders.
4. Build `RunningHub MiniMax H3 FL2VA Target`, then run `FL2VA Encode`.
5. Connect the same target to `Empty AV Latent`.
6. Run `Dual Sigma Sampler`, `Decode Video + Audio`, `CreateVideo`, and
   `SaveVideo`.

Workflows, one per legal signature:
[`fl2va_first_frame.json`](examples/workflows/fl2va_first_frame.json) ·
[`fl2va_last_frame.json`](examples/workflows/fl2va_last_frame.json) ·
[`fl2va_first_last_frame.json`](examples/workflows/fl2va_first_last_frame.json).
Replace the placeholder input image name before queueing either workflow.

## Ref2VA workflow

Ref2VA references are ordered. Chain the optional `references` input when
adding each image, audio, video, or video+audio item; changing the chain order
changes the multimodal presentation and conditioning rows.

1. Load source media with the standard ComfyUI `LoadImage`, `LoadAudio`, or
   `LoadVideo` nodes.
2. Append each item with the matching `RunningHub MiniMax H3 Ref2VA ... Reference` node.
3. Load Ref2VA DiT, Qwen3-VL, and VAE with the three Ref2VA loaders.
4. Feed the final ordered reference chain to both `Ref2VA Target` and
   `Ref2VA Encode`.
5. Finish with `Empty AV Latent`, `Dual Sigma Sampler`,
   `Decode Video + Audio`, `CreateVideo`, and `SaveVideo`.

Workflows, one per reference shape:
[`ref2va_image.json`](examples/workflows/ref2va_image.json) ·
[`ref2va_image_audio.json`](examples/workflows/ref2va_image_audio.json) ·
[`ref2va_video_audio.json`](examples/workflows/ref2va_video_audio.json).
Replace both placeholder media names before queueing either workflow.

`Ref2VA Encode` exposes `ref_image_size`, which decides how large each
reference image is resolved:

- `match` (default) scales the reference down — never up — to the generation
  canvas' pixel area, keeping its aspect ratio.
- `max` keeps the reference pipeline's independent 2048px short edge, the best
  identity fidelity.

Reference tokens ride through every sampling step, so `max` can be several
times slower than `match` on the same canvas. Workflows saved before this
option existed now run `match`; set it to `max` to reproduce their earlier
output exactly. Switching modes re-encodes rather than reusing a cached one.

Ref2VA video references are normalized to the official 24 fps preparation
path; the Qwen presentation samples that prepared sequence at 2 fps. A
`video_audio` reference must contain a soundtrack. Reference audio is prepared
for the model's stereo/32 kHz VAE path. Comfy `AUDIO` with more than two
channels (no layout metadata) is mean-downmixed to stereo at the reference
node / VAE boundary; prefer file/video references when you need ffmpeg's
layout-aware `-ac 2`.

## Target and sampler semantics

- Public target duration is 5–15 seconds. The runtime aligns the requested
  frame count upward to MiniMax-H3's `17n+5` temporal boundary. For example,
  a 5.0-second request at 24 fps resolves to 124 frames.
- `auto` FL2VA geometry follows the keyframe media. A finite aspect ratio uses
  the official `adapt_shape_v1` canvas policy. Ref2VA uses the official aspect
  buckets (`21:9`, `16:9`, `4:3`, `1:1`, `3:4`, `9:16`); its `auto` default is
  16:9.
- `Ref2VA Target` also accepts optional `width` and `height`. Leaving both at
  `0` preserves the bucket policy above; setting both makes that explicit
  canvas authoritative. Values must be multiples of 32, stay within a 1:4–4:1
  ratio, and respect the H3 pixel cap.
- Ref2VA duration `0` means infer the duration from exactly one real
  audio-bearing reference. Use an explicit 5–15 second value when there are
  zero or multiple audio-bearing references.
- The sampler uses separate video and audio noise streams. Visual condition
  rows are pinned at sigma `0.999`; audio-reference rows are pinned at sigma
  `1.0` at every step. With 50 sigma points the model performs 49 DiT forwards.
- The target, ordered conditions, partition, and release/component
  fingerprints are checked across encoder, sampler, and decoder. Cross-wiring
  FL2VA/Ref2VA components fails closed instead of producing undefined output.

## V2A (video → audio, optional)

Set `denoise_video=False` on `Dual Sigma Sampler` to freeze `av_latent.video`
as a clean visual condition (timestep floor `0.999`) and denoise audio only.
Requires a **T2VA** packed layout (no prior visual condition rows).

Typical graph:

1. `T2VA Target` + `Empty AV Latent`
2. `Encode Video → AV Latent` (VAE + `IMAGE` frames aligned to target), or
   `Separate` / `Combine AV Latent` to assemble a non-zero video shell
3. `T2VA Text Encode` + `Dual Sigma Sampler` with `denoise_video=false`
4. `Decode Video + Audio` (video is the input latent; audio is newly sampled)

All-zero `Empty AV Latent` video is rejected. Do not enable V2A on
FL2VA/Ref2VA layouts that already carry visual condition rows.

## Frame-rate conditioning (experimental, optional)

`RunningHub MiniMax H3 Frame Rate (Experimental)` mirrors PR#15210. It is **not** part of
the official training contract and does **not** change the `target.fps=24` grid:

- `adaln=True`: add an fps sinusoid into `TimeEmbedder` (even `24` is not a
  no-op); compatible with AdaLN precompute (stored in the cache key)
- `temporal_rope=True`: scale video-row temporal RoPE low frequencies by
  `24/fps` (optional hard/linear/smoothstep frequency and sigma profiles);
  no-op at 24 fps

Wire `Model Loader` → `Frame Rate` → `Dual Sigma Sampler`. After changing fps,
reload the DiT if AdaLN weights were already released.

## Optional single-GPU acceleration

This plugin targets **single-GPU** Comfy. There is no multi-GPU / Ulysses gate.
Upstream 4×H200 numbers are knobs/quality references only; single-GPU gains come
from fewer DiT calls (velocity-cache) or skipped blocks (Cache-DiT). Default
`accel=off`.

| Value | Behavior | Single-GPU note |
| --- | --- | --- |
| `off` | Disabled (GT-safe) | Default |
| `auto` | On validated 1344×768/124f/50steps/shifts 12·3, prefer velocity-cache | Good first try |
| `minimax-h3-velocity-cache-v1` | Whole-step velocity reuse + Taylor (no extra package) | **Preferred** |
| `minimax-h3-cache-v1` | Cache-DiT DBCache (`pip install cache-dit>=1.3.0`) | Alternative |
| `manual-velocity` / `manual-cache-dit` | Tune stride or RDT/MC/warmup | Debug |

Upstream references: ~**3.2×** velocity-cache, ~**2×** Cache-DiT on 4×H200.
Approximate—do **not** use as consistency GT. Profiles live under
`minimax_h3_nodes/runtime/profiles/`. Sampler logs actual vs theoretical DiT
call counts when velocity-cache runs; `auto` miss / `manual-*` also log the
workload and that the path is non-GT.

Set `accel` on the sampler in any of the bundled workflows under
[`examples/workflows/`](examples/workflows). Give Ref2VA Target an
explicit width/height: leaving them empty resolves to 1344×768 by aspect ratio
and costs far more.

Independently of `accel`, two fused-kernel paths engage automatically when the
installed Comfy exposes them (both from upstream PR #15224). Each is probed once
per process and logged; when the entry point is missing — older Comfy, no
comfy-kitchen, non-CUDA device — the existing PyTorch path runs unchanged.

| Setting | Kernel | What it saves |
| --- | --- | --- |
| `OPT_INT8_FUSED_SWIGLU` | `comfy.ops.linear_input_act` | INT8 MLP: swiglu folds into the activation quantizer, dropping one full-size intermediate per layer per step |
| `OPT_FUSED_QK_ROPE` | `comfy.quant_ops.ck.rms_rope_split_half_` | Attention: per-head RMSNorm + split-half RoPE in one pass, written in place on the qkv buffer |

Both live in `minimax_h3_nodes/runtime/h3_settings.py`;
`OPT_FUSED_QK_ROPE_CUDA_ONLY` keeps the RoPE kernel off non-CUDA devices, where
comfy-kitchen has no implementation. The fused RoPE path also steps aside when
gradients are live, since it rewrites autograd views in place.

## INT8 conversion and VAE merge

Run conversion from this repository and keep each partition separate:

```bash
cd custom_nodes/ComfyUI-RH-MiniMax-H3
BASE=/path/to/ComfyUI/models/diffusers/MiniMax-H3

python3 tools/quantize_int8_convrot.py \
  --src "$BASE/FL2VA/transformer" --device cuda --verify
python3 tools/quantize_int8_convrot.py \
  --src "$BASE/Ref2VA/transformer" --device cuda --verify

python3 tools/quantize_text_encoder_int8_convrot.py \
  --src "$BASE/FL2VA/text_encoder" --device cuda --verify
python3 tools/quantize_text_encoder_int8_convrot.py \
  --src "$BASE/Ref2VA/text_encoder" --device cuda --verify

python3 tools/merge_vae.py --src "$BASE/FL2VA"
python3 tools/merge_vae.py --src "$BASE/Ref2VA"
```

The VAE is merged, not INT8-quantized. Do not repair one partition with files
from the other partition, even when filenames look identical. Verify the
downloaded checkpoint before conversion.

Each tool emits a **component directory** (`config.json` + a single-file weight +
`quant_meta.json`). To use the flat dedicated root, move the `.safetensors` out
of it into `models/MiniMax-H3/` — the filename already encodes model, component
type and quantization format, which is what the nodes classify on, and the
config keeps coming from the sharded release under `$BASE`:

```bash
FLAT=/path/to/ComfyUI/models/MiniMax-H3
mkdir -p "$FLAT"
mv "$BASE/FL2VA/transformer_int8_convrot/MiniMax-H3-FL2VA-int8_convrot.safetensors" "$FLAT/"
mv "$BASE/Ref2VA/transformer_int8_convrot/MiniMax-H3-Ref2VA-int8_convrot.safetensors" "$FLAT/"
mv "$BASE/FL2VA/text_encoder_int8_convrot/qwen3-vl-32b-int8_convrot.safetensors" "$FLAT/"
mv "$BASE/FL2VA/vae/video_vae/MiniMax-H3-video_vae.safetensors" "$FLAT/"
mv "$BASE/FL2VA/vae/audio_vae/MiniMax-H3-audio_vae.safetensors" "$FLAT/"
```

Component directories left inside the release keep working; both shapes show up
in the matching per-type dropdown.

## AdaLN curve-table DiT (optional, ~40% smaller checkpoint)

Every DiT layer carries a `[96768, 2688]` adaLN projection — 26 GB in total,
39% of the BF16 DiT and 55% of the INT8 one (adaLN is never quantized). Its
input is only the one-dimensional curve `silu(time_embedder(t))`, so projecting
that curve onto a shared rank-`k` basis folds the basis into each layer's
weight (`[96768, k]`) and replaces the time embedder with an `adaln_t_table`
`[grid, k]` sampled table read by linear interpolation. This is the checkpoint
format introduced by upstream PR #15224; the loader detects it from the
`adaln_t_table` tensor, so both variants load through the same nodes.

```bash
python3 tools/convert_adaln_curve.py \
  --src "$BASE/FL2VA/transformer" --verify           # BF16: 66.3 GiB -> ~40 GiB
python3 tools/convert_adaln_curve.py \
  --src "$BASE/FL2VA/transformer_int8_convrot" --verify   # INT8: 47.0 GiB -> ~21 GiB
```

The output lands in `<src>_adaln_curve/` and appears in the DiT selector as its
own model name. `--verify` compares the curve path against the real adaLN
output at random off-grid timesteps and aborts below `--cosine-floor` (0.9999);
raise `--rank` / `--grid` if it does. Defaults are rank 64 / grid 1024.

Trade-offs versus the runtime adaLN precompute (which stays the default for
stock checkpoints):

- Smaller on disk, no precompute pass, no modulation cache, any timestep works.
- The adaLN input is a rank-`k` approximation instead of exact.
- The experimental Frame Rate node's `adaln` mode needs the time embedder and is
  therefore rejected on curve checkpoints; its `temporal_rope` mode still works.

## Local validation

```bash
python3 -m compileall -q minimax_h3_nodes tools tests
python3 -m unittest discover -s tests -v
```

These checks cover local structure and CPU-testable contracts. Passing them is
not a substitute for a real CUDA run with the complete released weights.

## License and upstream

Plugin code is distributed under the repository's Apache-2.0 license. Model
weights are not included and remain subject to their upstream license and
terms. The implementation is based on the official
[MiniMax-H3 source package](https://github.com/MiniMax-AI-Dev/Internal-0727-private-3).