# FLUX.2 Setup in ComfyUI — Full Reproduction Recipe

## Hardware Context (This Session)

- Proxmox CT 204, ROCm 6.2, PyTorch 2.6.0 (ROCm build)
- AMD Ryzen AI 9 HX PRO 370 w/ Radeon 890M (gfx1150)
- `HSA_OVERRIDE_GFX_VERSION=11.0.0` required for gfx1150
- 18GB "VRAM" reported; ~8.5 GB disk free after downloads

## Timeline

| Step | Result |
|------|--------|
| FLUX.1-dev E2E | ✅ Works in 46s (512×512, 4 steps) |
| FLUX.2 with FLUX.1 CLIP/T5 | ❌ `mat1 and mat2 shapes cannot be multiplied (512x4096 and 12288x4096)` |
| FLUX.2 with Qwen3VL + ae.safetensors | ❌ `expected input[1, 128, 32, 32] to have 16 channels, but got 128 channels instead` |
| FLUX.2 with Qwen3VL + taef2 | ✅ Success ~110s (1024×1024, 4 steps) |

## Required Models

### 1. UNet (GGUF)

```bash
# ~5.4 GB
wget https://huggingface.co/unsloth/FLUX.2-klein-9B-GGUF/resolve/main/flux-2-klein-9b-Q4_K_S.gguf
# → models/unet/flux-2-klein-9b-Q4_K_S.gguf
```

### 2. Text Encoder (Qwen3-VL-8B, GGUF)

**CRITICAL:** FLUX.2 uses Qwen3-VL-8B, NOT CLIP-L + T5XXL.

```bash
# ~4.7 GB — Q4_K_M quantization
wget https://huggingface.co/Qwen/Qwen3-VL-8B-Instruct-GGUF/resolve/main/Qwen3VL-8B-Instruct-Q4_K_M.gguf
# → models/clip/Qwen3VL-8B-Instruct-Q4_K_M.gguf
```

Alternative: `Qwen3-VL-8B-Instruct-Q8_0.gguf` (~8.3 GB) for higher quality.

The GGUF detection logic in ComfyUI (`comfy/sd.py:detect_te_model`) identifies this model by:
- `model.layers.0.self_attn.q_proj.weight` shape = `[4096, 4096]`
- `num_hidden_layers = 36`
→ maps to `TEModel.QWEN3VL_8B`

### 3. VAE — TWO OPTIONS

**Option A: TAEF2 (Tiny AutoEncoder, fast, lower quality)**

```bash
# ~5 MB total, public, no auth needed
cd models/vae_approx
curl -LO https://github.com/madebyollin/taesd/raw/main/taef2_encoder.pth
curl -LO https://github.com/madebyollin/taesd/raw/main/taef2_decoder.pth
# Reference as vae_name: "taef2" in VAELoader node
```

**Option B: Full FLUX.2 VAE (`flux2_vae.safetensors`)**

```bash
# ~160 MB, gated repo (BFL license acceptance required)
# From: black-forest-labs/FLUX.2-klein-9B vae/diffusion_pytorch_model.safetensors
# Save as: models/vae/flux2_vae.safetensors
```

The FLUX.1 VAE (`ae.safetensors`, 16 channels) is **incompatible** with FLUX.2 (128 channels).

## ComfyUI Workflow (API JSON)

```json
{
  "1": {
    "inputs": {"unet_name": "flux-2-klein-9b-Q4_K_S.gguf"},
    "class_type": "UnetLoaderGGUF"
  },
  "2": {
    "inputs": {
      "clip_name": "Qwen3VL-8B-Instruct-Q4_K_M.gguf",
      "type": "flux2"
    },
    "class_type": "CLIPLoaderGGUF"
  },
  "3": {
    "inputs": {"vae_name": "taef2"},
    "class_type": "VAELoader"
  },
  "4": {
    "inputs": {"width": 1024, "height": 1024, "batch_size": 1},
    "class_type": "EmptyFlux2LatentImage"
  },
  "5": {
    "inputs": {
      "text": "A beautiful mountain lake at sunset, photorealistic, 4k",
      "clip": ["2", 0]
    },
    "class_type": "CLIPTextEncode"
  },
  "6": {
    "inputs": {"text": "", "clip": ["2", 0]},
    "class_type": "CLIPTextEncode"
  },
  "7": {
    "inputs": {
      "seed": 42,
      "steps": 4,
      "cfg": 1.0,
      "sampler_name": "euler",
      "scheduler": "simple",
      "denoise": 1.0,
      "model": ["1", 0],
      "positive": ["5", 0],
      "negative": ["6", 0],
      "latent_image": ["4", 0]
    },
    "class_type": "KSampler"
  },
  "8": {
    "inputs": {"samples": ["7", 0], "vae": ["3", 0]},
    "class_type": "VAEDecode"
  },
  "9": {
    "inputs": {"filename_prefix": "flux2_out", "images": ["8", 0]},
    "class_type": "SaveImage"
  }
}
```

### Key node differences from FLUX.1

| Node | FLUX.1 | FLUX.2 |
|------|--------|--------|
| CLIP loader | `DualCLIPLoaderGGUF` (clip_l + t5xxl) | `CLIPLoaderGGUF` (single Qwen3VL) |
| CLIP type | `"flux"` | `"flux2"` |
| Empty latent | `EmptyLatentImage` (16 channels) | `EmptyFlux2LatentImage` (128 channels) |
| VAE | `ae.safetensors` | `taef2` or `flux2_vae.safetensors` |

## ROCm gfx1150 Workaround

gfx1150 (RDNA3.5, Radeon 890M) is not fully supported by ROCm 6.2. Set override before launch:

```bash
export HSA_OVERRIDE_GFX_VERSION=11.0.0
python main.py --listen 0.0.0.0 --port 8188
```

Without this, CLIP encoding fails with:
```
RuntimeError: HIP error: invalid device function
```

## Performance (gfx1150, ROCm 6.2)

| Pipeline | Resolution | Steps | Time |
|----------|-----------|-------|------|
| FLUX.1-dev Q4_K_S + CLIP/T5 + ae.safetensors | 512×512 | 4 | ~46s |
| FLUX.2-klein Q4_K_S + Qwen3VL Q4_K_M + taef2 | 1024×1024 | 4 | ~110s |

FLUX.2 is slower despite fewer parameters because Qwen3VL-8B text encoding is heavier than CLIP+T5, and the TAEF2 decode takes extra time.

## Disk Space Budget

| Component | Size |
|-----------|------|
| FLUX.2 UNet Q4_K_S | 5.4 GB |
| Qwen3VL-8B Q4_K_M | 4.7 GB |
| taef2 encoder+decoder | 5 MB |
| **Total** | **~10.1 GB** |

Full FLUX.2 VAE adds ~160 MB. Q8_0 text encoder adds ~3.6 GB more.

## Common Errors

### `mat1 and mat2 shapes cannot be multiplied (512x4096 and 12288x4096)`
**Cause:** Using CLIP-L + T5XXL (FLUX.1 encoders) with FLUX.2 UNet.
**Fix:** Switch to `Qwen3VL-8B-Instruct-Q4_K_M.gguf` + `CLIPLoaderGGUF` with `"type": "flux2"`.

### `expected input[1, 128, 32, 32] to have 16 channels, but got 128 channels instead`
**Cause:** Using FLUX.1 VAE (`ae.safetensors`) with FLUX.2 latents.
**Fix:** Use `taef2` or download dedicated `flux2_vae.safetensors`.

### `HIP error: invalid device function`
**Cause:** ROCm doesn't natively support gfx1150.
**Fix:** `export HSA_OVERRIDE_GFX_VERSION=11.0.0` before starting ComfyUI.

### `RuntimeError: The expanded size of the tensor (512) must match ...`
**Cause:** Using `EmptyLatentImage` (16-channel) instead of `EmptyFlux2LatentImage` (128-channel).
**Fix:** Change node class to `EmptyFlux2LatentImage`.

## References

- ComfyUI `comfy/model_base.py` lines 1057-1066: `class Flux2(Flux)`
- ComfyUI `comfy/latent_formats.py` line 192: `class Flux2(LatentFormat)` with `latent_channels = 128`
- ComfyUI `comfy/sd.py` lines 1631-1634: FLUX2 CLIPType routes to `klein_te` with Qwen3VL
- TAEF2 source: https://github.com/madebyollin/taesd
- Unsloth GGUF: https://huggingface.co/unsloth/FLUX.2-klein-9B-GGUF
- Qwen GGUF: https://huggingface.co/Qwen/Qwen3-VL-8B-Instruct-GGUF
