fix: handle filesystem errors during lora and upscaler cache scan (#2064)

Co-authored-by: leejet <leejet714@gmail.com>

README.md

@@ -64,6 +64,7 @@ API and command-line option may change frequently.***
     - [HiDream-O1-Image](./docs/hidream_o1_image.md)
     - [Ideogram4](./docs/ideogram4.md)
     - [LLaDA-Image](./docs/llada_image.md)
+    - [PixArt](./docs/pixart.md)
   - [Image Edit Models](./docs/edit.md)
     - [FLUX.1-Kontext-dev](./docs/kontext.md)
     - [Qwen Image Edit series](./docs/qwen_image_edit.md)

docker/Dockerfile

@@ -40,4 +40,6 @@ RUN printf '#!/bin/sh\nexec /sd.cpp/bin/sd-cli "$@"\n' > /sd-cli && \
     printf '#!/bin/sh\nexec /sd.cpp/bin/sd-server "$@"\n' > /sd-server && \
     chmod +x /sd-cli /sd-server
 
+WORKDIR /sd.cpp
+
 ENTRYPOINT [ "/sd-cli" ]

docker/Dockerfile.cuda

@@ -57,4 +57,6 @@ RUN printf '#!/bin/sh\nexec /sd.cpp/bin/sd-cli "$@"\n' > /sd-cli && \
     printf '#!/bin/sh\nexec /sd.cpp/bin/sd-server "$@"\n' > /sd-server && \
     chmod +x /sd-cli /sd-server
 
+WORKDIR /sd.cpp
+
 ENTRYPOINT [ "/sd-cli" ]

docker/Dockerfile.musa

@@ -42,4 +42,6 @@ RUN printf '#!/bin/sh\nexec /sd.cpp/bin/sd-cli "$@"\n' > /sd-cli && \
     printf '#!/bin/sh\nexec /sd.cpp/bin/sd-server "$@"\n' > /sd-server && \
     chmod +x /sd-cli /sd-server
 
+WORKDIR /sd.cpp
+
 ENTRYPOINT [ "/sd-cli" ]

docker/Dockerfile.sycl

@@ -29,4 +29,6 @@ FROM intel/oneapi-basekit:${SYCL_VERSION}-devel-ubuntu24.04 AS runtime
 COPY --from=build /sd.cpp/build/bin/sd-cli /sd-cli
 COPY --from=build /sd.cpp/build/bin/sd-server /sd-server
 
+WORKDIR /sd.cpp
+
 ENTRYPOINT [ "/sd-cli" ]

docker/Dockerfile.vulkan

@@ -41,4 +41,6 @@ RUN printf '#!/bin/sh\nexec /sd.cpp/bin/sd-cli "$@"\n' > /sd-cli && \
     printf '#!/bin/sh\nexec /sd.cpp/bin/sd-server "$@"\n' > /sd-server && \
     chmod +x /sd-cli /sd-server
 
+WORKDIR /sd.cpp
+
 ENTRYPOINT [ "/sd-cli" ]

docs/performance.md

@@ -21,6 +21,54 @@ CPU fallback. It excludes weights and cache buffers. Within a runner lifecycle,
 the summary is printed only on the first graph or when backend capacities or the
 segment count change.
 
+## Use VAE tiling to reduce encode and decode memory usage.
+
+`--vae-tiling` enables spatial tiling for both VAE encoding and decoding. The
+default tile size is 256x256 **image pixels**, independent of the VAE scale factor:
+
+```shell
+--vae-tiling --vae-tile-size 256x256 --vae-tile-overlap 0.5
+```
+
+`--vae-tile-size` accepts one size or `WIDTHxHEIGHT`. A zero dimension uses the
+256-pixel default. Sizes are rounded down to a multiple of the VAE scale factor
+and capped at the current input dimensions. Explicit sizes below four latent
+pixels per axis (or the full axis when it is smaller) are rejected. Encoding and
+decoding use the same spatial sizes, without an additional encoding multiplier.
+Inputs that fit within a tile are processed as one tile.
+
+For a 512x512 image with the default 50% overlap, both encoding and decoding use
+3x3 tiles. A 256-pixel tile corresponds to 32 latent pixels for an 8x VAE, 16 for
+a 16x VAE, and 8 for a 32x VAE. Smaller tiles reduce each graph's memory demand,
+but overlapping work can increase processing time and tiling can affect image
+quality, especially during encoding. Use larger tiles when more context is needed.
+
+`--vae-relative-tile-size` overrides the absolute size on each axis with a positive
+value. Values up to and including 1 specify a fraction of the current input size;
+values greater than 1 specify a target number of tiles per axis, accounting for
+overlap. For example, `0.5x0.5` uses half the width and height in both encode and
+decode. The target overlap is clamped to 0 through 0.5 and the actual overlap is
+adjusted to fit the image. Size and overlap options require `--vae-tiling`.
+
+**Migration:** `--vae-tile-size` and the C/JSON fields `tile_size_w` and
+`tile_size_h` now use image pixels instead of latent units. The C/JSON fields
+`tile_size_x/y` have been renamed to `tile_size_w/h`, and `rel_size_x/y` to
+`rel_size_w/h`. The command-line option names are unchanged. For example, an old
+decode tile size of 32 corresponds to 256 pixels for an 8x VAE or 512 pixels for a
+16x VAE. Encoding no longer enlarges explicit or relative tile sizes.
+
+The main VAE decode path retries allocation failures with smaller tiles, even
+without `--vae-tiling`. Supported video VAEs first try temporal tiling; spatial
+retries use at most 256-pixel tiles initially and then halve the effective tile
+dimensions down to the minimum size. Each spatial retry must reduce the effective
+tile size. These runtime adjustments do not change the caller's parameters.
+Execution failures are not retried, and encoding has no automatic OOM retry.
+
+`--temporal-tiling` remains independent of spatial tiling. MiniMax H3 always uses
+spatial tiling (256x256 pixels and 25% overlap by default) and its own temporal
+windows. With `--vae-tiling`, its overlap follows `--vae-tile-overlap`; explicit
+spatial sizes are honored.
+
 ## Offload weights to the CPU to save VRAM without reducing generation speed.
 
 Using `--offload-to-cpu` allows you to offload weights to the CPU, saving VRAM without reducing generation speed.

docs/pixart.md

@@ -0,0 +1,46 @@
+# How to Use
+
+You can run PixArt-α / PixArt-Σ with stable-diffusion.cpp.
+
+PixArt is a DiT-based text-to-image model family conditioned by a T5-XXL text
+encoder and a 4-channel VAE: SDXL-style for PixArt-Σ and SD1.x-style for PixArt-α.
+
+## Download weights
+
+- Download the transformer (diffusion model)
+    - PixArt-Σ XL-2 1024-MS: https://huggingface.co/PixArt-alpha/PixArt-Sigma-XL-2-1024-MS/tree/main/transformer
+    - PixArt-α XL-2 1024-MS: https://huggingface.co/PixArt-alpha/PixArt-XL-2-1024-MS/tree/main/transformer
+- Download the T5-XXL text encoder
+    - safetensors: https://huggingface.co/PixArt-alpha/PixArt-Sigma-XL-2-1024-MS/tree/main/text_encoder
+- Download the VAE
+    - PixArt-Σ: https://huggingface.co/PixArt-alpha/PixArt-Sigma-XL-2-1024-MS/tree/main/vae
+    - PixArt-α: https://huggingface.co/PixArt-alpha/PixArt-XL-2-1024-MS/tree/main/vae
+    - Use the VAE matching the checkpoint's latent space. For TAE decoding or
+      preview, use TAESDXL for PixArt-Σ and TAESD for PixArt-α.
+- Tokenizer: the T5 vocabulary is embedded; no extra tokenizer file is needed.
+
+## Examples
+
+```
+.\bin\Release\sd-cli.exe --diffusion-model ..\models\diffusion_models\pixart_sigma_xl2_1024_ms.safetensors --t5xxl ..\models\text_encoders\t5xxl.safetensors --vae ..\models\vae\pixart_vae.safetensors -p "a lovely cat" --cfg-scale 4.5 -W 1024 -H 1024 --steps 20 -v
+```
+
+## Notes
+
+- The VAE scaling factor defaults to `0.13025` for PixArt-Σ. PixArt-α
+  checkpoints with resolution micro-condition weights use `0.18215`.
+  PixArt-α 512 has the same tensor layout as PixArt-Σ, so it requires an
+  explicit override: `--model-args "pixart_vae_scale_factor=0.18215"`.
+  This argument can also override the scale for other compatible checkpoints.
+- PixArt-Σ checkpoints compute 2D sincos positional embeddings at runtime;
+  the trained grid is 64x64 patches with an interpolation scale of 2.
+  For checkpoints trained at a different resolution, the positional embedding
+  parameters can be adjusted via model args:
+  `--model-args "pixart_pos_embed_base_size=<trained grid>,pixart_interpolation_scale=<scale>"`
+  (e.g. `pixart_pos_embed_base_size=32,pixart_interpolation_scale=1,pixart_vae_scale_factor=0.18215` for
+  PixArt-α XL-2 512).
+- Checkpoints carrying resolution/aspect-ratio micro-condition weights are
+  detected but those conditions are not applied yet; a warning is logged and
+  generation proceeds with the timestep embedding only.
+- The transformer predicts 8 channels (noise + learned variance); only the
+  noise half is used for sampling, matching the reference implementation.

docs/wan.md

@@ -40,6 +40,9 @@ Wan models require `-M vid_gen`, including single-frame generation. `--video-fra
             - safetensors: https://huggingface.co/Comfy-Org/Wan_2.2_ComfyUI_Repackaged/tree/main/split_files/diffusion_models
             - gguf: https://huggingface.co/QuantStack/Wan2.2-S2V-14B-GGUF/tree/main
             - int8_convrot safetensors: https://huggingface.co/noctrex/Wan2.2-S2V-14B-int8_convrot
+        - Wan2.2 VACE-Fun A14B
+            - safetensors: https://huggingface.co/alibaba-pai/Wan2.2-VACE-Fun-A14B
+            - gguf: https://huggingface.co/QuantStack/Wan2.2-VACE-Fun-A14B-GGUF/tree/main
 - Download vae
     - wan_2.1_vae (for all the wan model except Wan2.2 TI2V 5B)
         - safetensors: https://huggingface.co/Comfy-Org/Wan_2.1_ComfyUI_repackaged/blob/main/split_files/vae/wan_2.1_vae.safetensors
@@ -256,3 +259,25 @@ ffmpeg -i ..\..\ComfyUI\input\post+depth.mp4 -qscale:v 1 -vf fps=8 post+depth\fr
 ```
 
 <video src=../assets/wan/Wan2.1_14B_vace_v2v.mp4 controls="controls" muted="muted" type="video/mp4"></video>
+
+### Wan2.2 VACE-Fun A14B
+
+VACE-Fun runs as a MoE pair: `--diffusion-model` takes the low-noise expert and
+`--high-noise-diffusion-model` the high-noise one. Reference-to-video uses `-i`
+for the reference image, same as Wan2.1 VACE.
+
+#### R2V
+
+```
+.\bin\Release\sd-cli.exe -M vid_gen --diffusion-model ..\models\diffusion_models\Wan2.2-VACE-Fun-A14B-low-noise-Q8_0.gguf --high-noise-diffusion-model ..\models\diffusion_models\Wan2.2-VACE-Fun-A14B-high-noise-Q8_0.gguf --vae ..\models\vae\wan_2.1_vae.safetensors --t5xxl ..\models\text_encoders\umt5-xxl-encoder-Q8_0.gguf -p "a lovely cat" --cfg-scale 3.5 --sampling-method euler --steps 10 --high-noise-cfg-scale 3.5 --high-noise-sampling-method euler --high-noise-steps 8 -v -n "色调艳丽，过曝，静态，细节模糊不清，字幕，风格，作品，画作，画面，静止，整体发灰，最差质量，低质量，JPEG压缩残留，丑陋的，残缺的，多余的手指，画得不好的手部，画得不好的脸部， 畸形的，毁容的，形态畸形的肢体，手指融合，静止不动的画面，杂乱的背景，三条腿，背景人很多，倒着走" -W 832 -H 480 --diffusion-fa -i ..\assets\cat_with_sd_cpp_42.png --video-frames 33 --offload-to-cpu
+```
+
+<video src=../assets/wan/Wan2.2_A14B_vace_r2v.mp4 controls="controls" muted="muted" type="video/mp4"></video>
+
+#### T2V
+
+Same command without `-i` (VACE context is synthesized from an empty control
+video, like Wan2.1 VACE t2v).
+
+> On GPUs with ~12 GB VRAM, VACE also needs `--vae-tiling` — the control-video
+> encode can exceed the budget otherwise.

examples/common/common.cpp

@@ -1341,7 +1341,7 @@ ArgOptions SDGenerationParams::get_options() {
          &embed_image_metadata},
         {"",
          "--vae-tiling",
-         "process vae in tiles to reduce memory usage",
+         "process vae encode and decode in spatial tiles to reduce memory usage (default: 256x256 image pixels)",
          true,
          &vae_tiling_params.enabled},
         {"",
@@ -1605,12 +1605,12 @@ ArgOptions SDGenerationParams::get_options() {
         size_t x_pos              = tile_size_str.find('x');
         try {
             if (x_pos != std::string::npos) {
-                std::string tile_x_str        = tile_size_str.substr(0, x_pos);
-                std::string tile_y_str        = tile_size_str.substr(x_pos + 1);
-                vae_tiling_params.tile_size_x = std::stoi(tile_x_str);
-                vae_tiling_params.tile_size_y = std::stoi(tile_y_str);
+                std::string tile_w_str        = tile_size_str.substr(0, x_pos);
+                std::string tile_h_str        = tile_size_str.substr(x_pos + 1);
+                vae_tiling_params.tile_size_w = std::stoi(tile_w_str);
+                vae_tiling_params.tile_size_h = std::stoi(tile_h_str);
             } else {
-                vae_tiling_params.tile_size_x = vae_tiling_params.tile_size_y = std::stoi(tile_size_str);
+                vae_tiling_params.tile_size_w = vae_tiling_params.tile_size_h = std::stoi(tile_size_str);
             }
         } catch (const std::invalid_argument&) {
             return -1;
@@ -1628,12 +1628,12 @@ ArgOptions SDGenerationParams::get_options() {
         size_t x_pos             = rel_size_str.find('x');
         try {
             if (x_pos != std::string::npos) {
-                std::string rel_x_str        = rel_size_str.substr(0, x_pos);
-                std::string rel_y_str        = rel_size_str.substr(x_pos + 1);
-                vae_tiling_params.rel_size_x = std::stof(rel_x_str);
-                vae_tiling_params.rel_size_y = std::stof(rel_y_str);
+                std::string rel_w_str        = rel_size_str.substr(0, x_pos);
+                std::string rel_h_str        = rel_size_str.substr(x_pos + 1);
+                vae_tiling_params.rel_size_w = std::stof(rel_w_str);
+                vae_tiling_params.rel_size_h = std::stof(rel_h_str);
             } else {
-                vae_tiling_params.rel_size_x = vae_tiling_params.rel_size_y = std::stof(rel_size_str);
+                vae_tiling_params.rel_size_w = vae_tiling_params.rel_size_h = std::stof(rel_size_str);
             }
         } catch (const std::invalid_argument&) {
             return -1;
@@ -1763,11 +1763,11 @@ ArgOptions SDGenerationParams::get_options() {
          on_scm_policy_arg},
         {"",
          "--vae-tile-size",
-         "tile size for vae tiling in latent units, not image pixels, format [X]x[Y] (default: 32x32)",
+         "tile size for vae encode and decode in image pixels, format [W]x[H] or [S] (default: 256x256; requires --vae-tiling)",
          on_tile_size_arg},
         {"",
          "--vae-relative-tile-size",
-         "relative tile size for vae tiling, format [X]x[Y], in fraction of image size if < 1, in number of tiles per dim if >=1 (overrides --vae-tile-size)",
+         "relative tile size for vae encode and decode, format [W]x[H] or [S]: <=1 is a dimension fraction, >1 a target tile count (overrides --vae-tile-size; requires --vae-tiling)",
          on_relative_tile_size_arg},
         {"",
          "--prompt-file",
@@ -2224,20 +2224,20 @@ bool SDGenerationParams::from_json_str(
         if (tiling_json.contains("temporal_tiling") && tiling_json["temporal_tiling"].is_boolean()) {
             vae_tiling_params.temporal_tiling = tiling_json["temporal_tiling"];
         }
-        if (tiling_json.contains("tile_size_x") && tiling_json["tile_size_x"].is_number_integer()) {
-            vae_tiling_params.tile_size_x = tiling_json["tile_size_x"];
+        if (tiling_json.contains("tile_size_w") && tiling_json["tile_size_w"].is_number_integer()) {
+            vae_tiling_params.tile_size_w = tiling_json["tile_size_w"];
         }
-        if (tiling_json.contains("tile_size_y") && tiling_json["tile_size_y"].is_number_integer()) {
-            vae_tiling_params.tile_size_y = tiling_json["tile_size_y"];
+        if (tiling_json.contains("tile_size_h") && tiling_json["tile_size_h"].is_number_integer()) {
+            vae_tiling_params.tile_size_h = tiling_json["tile_size_h"];
         }
         if (tiling_json.contains("target_overlap") && tiling_json["target_overlap"].is_number()) {
             vae_tiling_params.target_overlap = tiling_json["target_overlap"];
         }
-        if (tiling_json.contains("rel_size_x") && tiling_json["rel_size_x"].is_number()) {
-            vae_tiling_params.rel_size_x = tiling_json["rel_size_x"];
+        if (tiling_json.contains("rel_size_w") && tiling_json["rel_size_w"].is_number()) {
+            vae_tiling_params.rel_size_w = tiling_json["rel_size_w"];
         }
-        if (tiling_json.contains("rel_size_y") && tiling_json["rel_size_y"].is_number()) {
-            vae_tiling_params.rel_size_y = tiling_json["rel_size_y"];
+        if (tiling_json.contains("rel_size_h") && tiling_json["rel_size_h"].is_number()) {
+            vae_tiling_params.rel_size_h = tiling_json["rel_size_h"];
         }
         if (tiling_json.contains("extra_tiling_args") && tiling_json["extra_tiling_args"].is_string()) {
             extra_tiling_args = tiling_json["extra_tiling_args"].get<std::string>();
@@ -2934,11 +2934,11 @@ std::string SDGenerationParams::to_string() const {
         << "  vae_tiling_params: { "
         << vae_tiling_params.enabled << ", "
         << vae_tiling_params.temporal_tiling << ", "
-        << vae_tiling_params.tile_size_x << ", "
-        << vae_tiling_params.tile_size_y << ", "
+        << vae_tiling_params.tile_size_w << ", "
+        << vae_tiling_params.tile_size_h << ", "
         << vae_tiling_params.target_overlap << ", "
-        << vae_tiling_params.rel_size_x << ", "
-        << vae_tiling_params.rel_size_y << ", "
+        << vae_tiling_params.rel_size_w << ", "
+        << vae_tiling_params.rel_size_h << ", "
         << "\"" << extra_tiling_args << "\" },\n"
         << "}";
     return oss.str();
@@ -3140,11 +3140,11 @@ std::string build_sdcpp_image_metadata_json(const SDContextParams& ctx_params,
         root["vae_tiling"] = {
             {"enabled", gen_params.vae_tiling_params.enabled},
             {"temporal_tiling", gen_params.vae_tiling_params.temporal_tiling},
-            {"tile_size_x", gen_params.vae_tiling_params.tile_size_x},
-            {"tile_size_y", gen_params.vae_tiling_params.tile_size_y},
+            {"tile_size_w", gen_params.vae_tiling_params.tile_size_w},
+            {"tile_size_h", gen_params.vae_tiling_params.tile_size_h},
             {"target_overlap", gen_params.vae_tiling_params.target_overlap},
-            {"rel_size_x", gen_params.vae_tiling_params.rel_size_x},
-            {"rel_size_y", gen_params.vae_tiling_params.rel_size_y},
+            {"rel_size_w", gen_params.vae_tiling_params.rel_size_w},
+            {"rel_size_h", gen_params.vae_tiling_params.rel_size_h},
             {"extra_tiling_args", gen_params.extra_tiling_args},
         };
     }

examples/server/api.md

@@ -524,11 +524,11 @@ Shared default fields used by both `img_gen` and `vid_gen`:
 | `vae_tiling_params` | `object` |
 | `vae_tiling_params.enabled` | `boolean` |
 | `vae_tiling_params.temporal_tiling` | `boolean` |
-| `vae_tiling_params.tile_size_x` | `integer` |
-| `vae_tiling_params.tile_size_y` | `integer` |
+| `vae_tiling_params.tile_size_w` | `integer` |
+| `vae_tiling_params.tile_size_h` | `integer` |
 | `vae_tiling_params.target_overlap` | `number` |
-| `vae_tiling_params.rel_size_x` | `number` |
-| `vae_tiling_params.rel_size_y` | `number` |
+| `vae_tiling_params.rel_size_w` | `number` |
+| `vae_tiling_params.rel_size_h` | `number` |
 | `vae_tiling_params.extra_tiling_args` | `string` |
 | `cache_mode` | `string` |
 | `cache_option` | `string` |
@@ -537,6 +537,8 @@ Shared default fields used by both `img_gen` and `vid_gen`:
 | `output_format` | `string` |
 | `output_compression` | `integer` |
 
+`vae_tiling_params.tile_size_w` and `tile_size_h` are in **image pixels**, with `0` selecting the 256-pixel default. Both encode and decode use these sizes without an encoding multiplier. Positive `rel_size_w`/`rel_size_h` values override the corresponding absolute size: values up to 1 are dimension fractions, and values greater than 1 are target tile counts. Set `enabled` to use spatial tiling. Sizes are aligned down to the VAE scale factor and capped at the input dimensions; explicit sizes below the minimum supported tile size are rejected. These fields previously used latent units; see [VAE tiling](../../docs/performance.md#use-vae-tiling-to-reduce-encode-and-decode-memory-usage) for migration and OOM retry behavior.
+
 `vae_tiling_params.extra_tiling_args` accepts a key=value list. Supported video VAEs accept `temporal_tile_frames` (alias `temporal_tile_size`, default `4`) and `temporal_tile_overlap` (default `1`).
 LTX and Wan preserve causal state between temporal tiles. Hunyuan Video and TAEHV use overlap blending. MiniMax H3 keeps its model-specific fixed temporal windows because its latent-to-frame mapping is non-linear.
 
@@ -767,11 +769,11 @@ Example:
   "vae_tiling_params": {
     "enabled": false,
     "temporal_tiling": false,
-    "tile_size_x": 0,
-    "tile_size_y": 0,
+    "tile_size_w": 0,
+    "tile_size_h": 0,
     "target_overlap": 0.5,
-    "rel_size_x": 0.0,
-    "rel_size_y": 0.0,
+    "rel_size_w": 0.0,
+    "rel_size_h": 0.0,
     "extra_tiling_args": ""
   },
 
@@ -900,11 +902,11 @@ Other native fields:
 | `vae_tiling_params` | `object` |
 | `vae_tiling_params.enabled` | `boolean` |
 | `vae_tiling_params.temporal_tiling` | `boolean` |
-| `vae_tiling_params.tile_size_x` | `integer` |
-| `vae_tiling_params.tile_size_y` | `integer` |
+| `vae_tiling_params.tile_size_w` | `integer` |
+| `vae_tiling_params.tile_size_h` | `integer` |
 | `vae_tiling_params.target_overlap` | `number` |
-| `vae_tiling_params.rel_size_x` | `number` |
-| `vae_tiling_params.rel_size_y` | `number` |
+| `vae_tiling_params.rel_size_w` | `number` |
+| `vae_tiling_params.rel_size_h` | `number` |
 | `vae_tiling_params.extra_tiling_args` | `string` |
 | `cache_mode` | `string` |
 | `cache_option` | `string` |
@@ -1115,11 +1117,11 @@ Example:
   "vae_tiling_params": {
     "enabled": false,
     "temporal_tiling": false,
-    "tile_size_x": 0,
-    "tile_size_y": 0,
+    "tile_size_w": 0,
+    "tile_size_h": 0,
     "target_overlap": 0.5,
-    "rel_size_x": 0.0,
-    "rel_size_y": 0.0,
+    "rel_size_w": 0.0,
+    "rel_size_h": 0.0,
     "extra_tiling_args": ""
   },
 
@@ -1240,11 +1242,11 @@ Other native fields:
 | `vae_tiling_params` | `object` |
 | `vae_tiling_params.enabled` | `boolean` |
 | `vae_tiling_params.temporal_tiling` | `boolean` |
-| `vae_tiling_params.tile_size_x` | `integer` |
-| `vae_tiling_params.tile_size_y` | `integer` |
+| `vae_tiling_params.tile_size_w` | `integer` |
+| `vae_tiling_params.tile_size_h` | `integer` |
 | `vae_tiling_params.target_overlap` | `number` |
-| `vae_tiling_params.rel_size_x` | `number` |
-| `vae_tiling_params.rel_size_y` | `number` |
+| `vae_tiling_params.rel_size_w` | `number` |
+| `vae_tiling_params.rel_size_h` | `number` |
 | `vae_tiling_params.extra_tiling_args` | `string` |
 | `cache_mode` | `string` |
 | `cache_option` | `string` |

examples/server/routes_sdcpp.cpp

@@ -78,11 +78,11 @@ static json make_vae_tiling_json(const sd_tiling_params_t& params) {
     return {
         {"enabled", params.enabled},
         {"temporal_tiling", params.temporal_tiling},
-        {"tile_size_x", params.tile_size_x},
-        {"tile_size_y", params.tile_size_y},
+        {"tile_size_w", params.tile_size_w},
+        {"tile_size_h", params.tile_size_h},
         {"target_overlap", params.target_overlap},
-        {"rel_size_x", params.rel_size_x},
-        {"rel_size_y", params.rel_size_y},
+        {"rel_size_w", params.rel_size_w},
+        {"rel_size_h", params.rel_size_h},
         {"extra_tiling_args", params.extra_tiling_args ? params.extra_tiling_args : ""},
     };
 }

examples/server/runtime.cpp

@@ -255,27 +255,48 @@ void refresh_lora_cache(ServerRuntime& rt) {
     std::vector<LoraEntry> new_cache;
 
     fs::path lora_dir = rt.ctx_params->lora_model_dir;
-    if (fs::exists(lora_dir) && fs::is_directory(lora_dir)) {
-        for (auto& entry : fs::recursive_directory_iterator(lora_dir, fs::directory_options::skip_permission_denied)) {
-            if (!entry.is_regular_file()) {
-                continue;
-            }
-            const fs::path& p = entry.path();
-            if (!is_supported_model_ext(p)) {
-                continue;
-            }
+    std::error_code ec;
+    if (fs::exists(lora_dir, ec) && !ec && fs::is_directory(lora_dir, ec) && !ec) {
+        try {
+            auto it = fs::recursive_directory_iterator(
+                lora_dir,
+                fs::directory_options::skip_permission_denied,
+                ec);
+            auto end = fs::recursive_directory_iterator();
+            while (!ec && it != end) {
+                std::error_code entry_ec;
+                bool is_reg = it->is_regular_file(entry_ec);
+                if (entry_ec || !is_reg) {
+                    it.increment(ec);
+                    continue;
+                }
+                const fs::path& p = it->path();
+                if (!is_supported_model_ext(p)) {
+                    it.increment(ec);
+                    continue;
+                }
 
-            LoraEntry lora_entry;
-            lora_entry.name     = p.stem().u8string();
-            lora_entry.fullpath = p.u8string();
-            std::string rel     = p.lexically_relative(lora_dir).u8string();
-            std::replace(rel.begin(), rel.end(), '\\', '/');
-            lora_entry.path = rel;
+                LoraEntry lora_entry;
+                lora_entry.name     = p.stem().u8string();
+                lora_entry.fullpath = p.u8string();
+                std::string rel     = p.lexically_relative(lora_dir).u8string();
+                std::replace(rel.begin(), rel.end(), '\\', '/');
+                lora_entry.path = rel;
 
-            new_cache.push_back(std::move(lora_entry));
+                new_cache.push_back(std::move(lora_entry));
+                it.increment(ec);
+            }
+        } catch (const std::exception& e) {
+            LOG_WARN("error while scanning lora directory '%s': %s", lora_dir.string().c_str(), e.what());
+            return;
         }
     }
 
+    if (ec) {
+        LOG_WARN("error while scanning lora directory '%s': %s", lora_dir.string().c_str(), ec.message().c_str());
+        return;
+    }
+
     std::sort(new_cache.begin(), new_cache.end(), [](const LoraEntry& a, const LoraEntry& b) {
         return a.path < b.path;
     });
@@ -302,40 +323,71 @@ void refresh_upscaler_cache(ServerRuntime& rt) {
     }
 
     fs::path upscaler_dir = rt.ctx_params->hires_upscalers_dir;
-    if (fs::exists(upscaler_dir) && fs::is_directory(upscaler_dir)) {
-        for (auto& entry : fs::directory_iterator(upscaler_dir)) {
-            if (!entry.is_regular_file()) {
-                continue;
-            }
-            const fs::path& p = entry.path();
-            if (!is_supported_model_ext(p)) {
-                continue;
-            }
+    std::error_code ec;
+    if (fs::exists(upscaler_dir, ec) && !ec && fs::is_directory(upscaler_dir, ec) && !ec) {
+        try {
+            auto it = fs::directory_iterator(
+                upscaler_dir,
+                fs::directory_options::skip_permission_denied,
+                ec);
+            auto end = fs::directory_iterator();
+            while (!ec && it != end) {
+                std::error_code entry_ec;
+                bool is_reg = it->is_regular_file(entry_ec);
+                if (entry_ec || !is_reg) {
+                    it.increment(ec);
+                    continue;
+                }
+                const fs::path& p = it->path();
+                if (!is_supported_model_ext(p)) {
+                    it.increment(ec);
+                    continue;
+                }
 
-            UpscalerEntry upscaler_entry;
-            upscaler_entry.name                 = p.stem().u8string();
-            upscaler_entry.fullpath             = fs::absolute(p).lexically_normal().u8string();
-            upscaler_entry.model_name           = "ESRGAN_4x";
-            upscaler_entry.path                 = p.filename().u8string();
-            upscaler_entry.file_size            = entry.file_size();
-            upscaler_entry.last_modified        = entry.last_write_time();
-            auto previous                       = std::find_if(previous_cache.begin(), previous_cache.end(), [&](const UpscalerEntry& cached) {
-                return cached.fullpath == upscaler_entry.fullpath &&
-                       cached.file_size == upscaler_entry.file_size &&
-                       cached.last_modified == upscaler_entry.last_modified;
-            });
-            upscaler_entry.image_upscale_factor = previous != previous_cache.end()
-                                                      ? previous->image_upscale_factor
-                                                      : get_upscaler_model_scale(upscaler_entry.fullpath.c_str());
-            if (upscaler_entry.image_upscale_factor > 0) {
-                upscaler_entry.scale      = upscaler_entry.image_upscale_factor;
-                upscaler_entry.model_name = "ESRGAN_" + std::to_string(upscaler_entry.scale) + "x";
-            }
+                UpscalerEntry upscaler_entry;
+                upscaler_entry.name = p.stem().u8string();
+                std::error_code abs_ec;
+                fs::path abs_path         = fs::absolute(p, abs_ec);
+                upscaler_entry.fullpath   = (abs_ec ? p : abs_path.lexically_normal()).u8string();
+                upscaler_entry.model_name = "ESRGAN_4x";
+                upscaler_entry.path       = p.filename().u8string();
 
-            new_cache.push_back(std::move(upscaler_entry));
+                std::error_code size_ec;
+                upscaler_entry.file_size = it->file_size(size_ec);
+                if (size_ec) {
+                    it.increment(ec);
+                    continue;
+                }
+
+                std::error_code time_ec;
+                upscaler_entry.last_modified        = it->last_write_time(time_ec);
+                auto previous                       = std::find_if(previous_cache.begin(), previous_cache.end(), [&](const UpscalerEntry& cached) {
+                    return cached.fullpath == upscaler_entry.fullpath &&
+                           cached.file_size == upscaler_entry.file_size &&
+                           (!time_ec && cached.last_modified == upscaler_entry.last_modified);
+                });
+                upscaler_entry.image_upscale_factor = previous != previous_cache.end()
+                                                          ? previous->image_upscale_factor
+                                                          : get_upscaler_model_scale(upscaler_entry.fullpath.c_str());
+                if (upscaler_entry.image_upscale_factor > 0) {
+                    upscaler_entry.scale      = upscaler_entry.image_upscale_factor;
+                    upscaler_entry.model_name = "ESRGAN_" + std::to_string(upscaler_entry.scale) + "x";
+                }
+
+                new_cache.push_back(std::move(upscaler_entry));
+                it.increment(ec);
+            }
+        } catch (const std::exception& e) {
+            LOG_WARN("error while scanning upscalers directory '%s': %s", upscaler_dir.string().c_str(), e.what());
+            return;
         }
     }
 
+    if (ec) {
+        LOG_WARN("error while scanning upscalers directory '%s': %s", upscaler_dir.string().c_str(), ec.message().c_str());
+        return;
+    }
+
     std::sort(new_cache.begin(), new_cache.end(), [](const UpscalerEntry& a, const UpscalerEntry& b) {
         return a.name < b.name;
     });

include/stable-diffusion.h

@@ -173,11 +173,13 @@ enum lora_apply_mode_t {
 typedef struct {
     bool enabled;
     bool temporal_tiling;
-    int tile_size_x;
-    int tile_size_y;
+    // Spatial tile dimensions in image pixels for both encode and decode; 0 uses 256.
+    int tile_size_w;
+    int tile_size_h;
     float target_overlap;
-    float rel_size_x;
-    float rel_size_y;
+    // Positive values override tile_size: <= 1 is a dimension fraction, > 1 a target tile count.
+    float rel_size_w;
+    float rel_size_h;
     const char* extra_tiling_args;
 } sd_tiling_params_t;
 

src/core/backend_fit.cpp

@@ -478,7 +478,12 @@ namespace sd::backend_fit {
         return true;
     }
 
-    bool prepare_vae_decode_retry_tiling(sd_tiling_params_t& tiling_params, bool prefer_temporal_tiling, ggml_status status) {
+    bool prepare_vae_decode_retry_tiling(sd_tiling_params_t& tiling_params,
+                                         bool prefer_temporal_tiling,
+                                         ggml_status status,
+                                         int latent_tile_size_w,
+                                         int latent_tile_size_h,
+                                         int scale_factor) {
         // Execution failures can leave the device unusable; tiling only helps with allocation failures.
         if (status != GGML_STATUS_ALLOC_FAILED) {
             return false;
@@ -487,19 +492,31 @@ namespace sd::backend_fit {
         if (prefer_temporal_tiling && !tiling_params.temporal_tiling) {
             tiling_params.temporal_tiling = true;
             retry_mode                    = tiling_params.enabled ? "spatial+temporal" : "temporal";
-        } else if (!tiling_params.enabled) {
-            tiling_params.enabled    = true;
-            tiling_params.rel_size_x = 0.5f;
-            tiling_params.rel_size_y = 0.5f;
-            if (tiling_params.tile_size_x <= 0) {
-                tiling_params.tile_size_x = 256;
-            }
-            if (tiling_params.tile_size_y <= 0) {
-                tiling_params.tile_size_y = 256;
-            }
-            retry_mode = tiling_params.temporal_tiling ? "spatial+temporal" : "spatial";
         } else {
-            return false;
+            if (latent_tile_size_w <= 0 || latent_tile_size_h <= 0 || scale_factor <= 0) {
+                return false;
+            }
+            auto smaller_tile = [&](int size) {
+                int next_size = size / 2;
+                if (!tiling_params.enabled) {
+                    next_size = std::min(next_size, 256 / scale_factor);
+                }
+                return std::min(size, std::max(4, next_size));
+            };
+            const int tile_size_w = smaller_tile(latent_tile_size_w);
+            const int tile_size_h = smaller_tile(latent_tile_size_h);
+            if (tile_size_w == latent_tile_size_w && tile_size_h == latent_tile_size_h) {
+                return false;
+            }
+            tiling_params.enabled     = true;
+            tiling_params.rel_size_w  = 0.0f;
+            tiling_params.rel_size_h  = 0.0f;
+            tiling_params.tile_size_w = tile_size_w * scale_factor;
+            tiling_params.tile_size_h = tile_size_h * scale_factor;
+            retry_mode                = tiling_params.temporal_tiling ? "spatial+temporal" : "spatial";
+            LOG_WARN("Reducing VAE decode tiles from %dx%d to %dx%d image pixels",
+                     latent_tile_size_w * scale_factor, latent_tile_size_h * scale_factor,
+                     tiling_params.tile_size_w, tiling_params.tile_size_h);
         }
 
         LOG_WARN("VAE decode ran out of memory; retrying with %s tiling",

src/core/backend_fit.h

@@ -17,7 +17,10 @@ namespace sd::backend_fit {
 
     bool prepare_vae_decode_retry_tiling(sd_tiling_params_t& tiling_params,
                                          bool prefer_temporal_tiling,
-                                         ggml_status status);
+                                         ggml_status status,
+                                         int latent_tile_size_w,
+                                         int latent_tile_size_h,
+                                         int scale_factor);
 
 }  // namespace sd::backend_fit
 

src/model.h

@@ -62,6 +62,7 @@ enum SDVersion {
     VERSION_SENSENOVA_U1_5,
     VERSION_LLADA_IMAGE,
     VERSION_ESRGAN,
+    VERSION_PIXART,
     VERSION_COUNT,
 };
 
@@ -252,6 +253,10 @@ static inline bool sd_version_is_sensenova_u1(SDVersion version) {
     return version == VERSION_SENSENOVA_U1_5;
 }
 
+static inline bool sd_version_is_pixart(SDVersion version) {
+    return version == VERSION_PIXART;
+}
+
 static inline bool sd_version_supports_video_generation(SDVersion version) {
     return version == VERSION_SVD || sd_version_is_wan(version) || sd_version_is_hunyuan_video(version) || sd_version_is_lingbot_video(version) || sd_version_is_ltxav(version) || sd_version_is_minimax_h3(version);
 }
@@ -320,7 +325,8 @@ static inline bool sd_version_is_dit(SDVersion version) {
         sd_version_is_sefi_image(version) ||
         sd_version_is_krea2(version) ||
         sd_version_is_mage_flow(version) ||
-        sd_version_is_sensenova_u1(version)) {
+        sd_version_is_sensenova_u1(version) ||
+        sd_version_is_pixart(version)) {
         return true;
     }
     return false;

src/model/diffusion/pixart.hpp

@@ -0,0 +1,399 @@
+#ifndef __SD_MODEL_DIFFUSION_PIXART_HPP__
+#define __SD_MODEL_DIFFUSION_PIXART_HPP__
+
+#include <algorithm>
+#include <cinttypes>
+#include <cmath>
+#include <vector>
+
+#include "core/ggml_extend.h"
+#include "core/ggml_runner.h"
+#include "core/util.h"
+#include "model/common/ggml_block.hpp"
+#include "model/diffusion/dit.hpp"
+#include "model/diffusion/mmdit.hpp"
+#include "model/diffusion/model.hpp"
+#include "model_loader.h"
+
+// Ref: https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/transformers/pixart_transformer_2d.py
+// Ref: https://github.com/PixArt-alpha/PixArt-sigma
+
+namespace PixArt {
+    constexpr int PIXART_GRAPH_SIZE = 20480;
+    constexpr int ADALN_EMBED_DIM   = 256;
+
+    struct PixArtConfig {
+        int64_t in_channels         = 4;
+        int64_t out_channels        = 8;  // learn_sigma: noise prediction + learned variance
+        int64_t hidden_size         = 1152;
+        int64_t cross_attention_dim = 1152;
+        int64_t caption_channels    = 4096;
+        int64_t num_heads           = 16;
+        int64_t patch_size          = 2;
+        int64_t ffn_dim             = 4608;
+        int64_t pos_embed_base_size = 64;
+        float interpolation_scale   = 2.f;
+        int num_layers              = 28;
+
+        static PixArtConfig detect_from_weights(const String2TensorStorage& weights, const std::string& prefix) {
+            PixArtConfig config;
+            auto find = [&](const std::string& suffix) -> const TensorStorage* {
+                auto it = weights.find(prefix + "." + suffix);
+                return it == weights.end() ? nullptr : &it->second;
+            };
+            if (auto w = find("x_embedder.proj.weight")) {
+                config.hidden_size = w->ne[3];
+                config.in_channels = w->ne[2];
+                config.patch_size  = w->ne[0];
+            }
+            if (auto w = find("final_layer.linear.weight")) {
+                config.out_channels = w->ne[1] / (config.patch_size * config.patch_size);
+            }
+            if (auto w = find("y_embedder.y_proj.fc1.weight")) {
+                config.caption_channels = w->ne[0];
+            }
+            if (auto w = find("blocks.0.cross_attn.kv_linear.weight")) {
+                config.cross_attention_dim = w->ne[0];
+            }
+            if (auto w = find("blocks.0.mlp.fc1.weight")) {
+                config.ffn_dim = w->ne[1];
+            }
+            if (find("csize_embedder.mlp.0.weight") != nullptr) {
+                LOG_WARN("pixart: resolution/aspect-ratio micro conditions are not supported; output may differ from the reference");
+            }
+            int layers                     = 0;
+            const std::string block_prefix = prefix + ".blocks.";
+            for (const auto& [name, _] : weights) {
+                if (starts_with(name, block_prefix)) {
+                    layers = std::max(layers, atoi(name.substr(block_prefix.size()).c_str()) + 1);
+                }
+            }
+            if (layers > 0) {
+                config.num_layers = layers;
+                LOG_VERBOSE("pixart: layers = %d, hidden_size = %" PRId64,
+                            layers, config.hidden_size);
+            }
+            return config;
+        }
+    };
+
+    // Mirrors diffusers get_2d_sincos_pos_embed for a (gh, gw) patch grid.
+    static std::vector<float> gen_2d_sincos_pos_embed(int64_t dim,
+                                                      int64_t gh,
+                                                      int64_t gw,
+                                                      int64_t base_size,
+                                                      float interpolation_scale) {
+        // diffusers: meshgrid(grid_w, grid_h, indexing="xy") -> grid[0]=w, grid[1]=h,
+        // embedding = concat(sincos(w), sincos(h))
+        std::vector<float> out(static_cast<size_t>(gh) * gw * dim);
+        int64_t quarter = dim / 4;
+        for (int64_t h = 0; h < gh; ++h) {
+            float pos_h = static_cast<float>(h) / (static_cast<float>(gh) / base_size) / interpolation_scale;
+            for (int64_t w = 0; w < gw; ++w) {
+                float pos_w  = static_cast<float>(w) / (static_cast<float>(gw) / base_size) / interpolation_scale;
+                float* dst_w = out.data() + (h * gw + w) * dim;
+                float* dst_h = dst_w + dim / 2;
+                for (int64_t i = 0; i < quarter; ++i) {
+                    float omega        = 1.f / powf(10000.f, static_cast<float>(i) / quarter);
+                    dst_w[i]           = sinf(pos_w * omega);
+                    dst_w[i + quarter] = cosf(pos_w * omega);
+                    dst_h[i]           = sinf(pos_h * omega);
+                    dst_h[i + quarter] = cosf(pos_h * omega);
+                }
+            }
+        }
+        return out;
+    }
+
+    class PixArtTimestepEmbedding : public GGMLBlock {
+    public:
+        PixArtTimestepEmbedding(int64_t in_channels, int64_t out_dim) {
+            blocks["mlp.0"] = std::make_shared<Linear>(in_channels, out_dim);
+            blocks["mlp.2"] = std::make_shared<Linear>(out_dim, out_dim);
+        }
+
+        ggml_tensor* forward(GGMLRunnerContext* ctx, ggml_tensor* x) {
+            x = std::dynamic_pointer_cast<Linear>(blocks["mlp.0"])->forward(ctx, x);
+            x = ggml_silu(ctx->ggml_ctx, x);
+            return std::dynamic_pointer_cast<Linear>(blocks["mlp.2"])->forward(ctx, x);
+        }
+    };
+
+    class PixArtAttention : public GGMLBlock {
+        int64_t num_heads;
+        bool self_attention;
+
+    public:
+        PixArtAttention(int64_t dim, int64_t num_heads, int64_t context_dim, bool self_attention)
+            : num_heads(num_heads), self_attention(self_attention) {
+            if (self_attention) {
+                blocks["qkv"] = std::make_shared<Linear>(dim, 3 * dim);
+            } else {
+                blocks["q_linear"]  = std::make_shared<Linear>(dim, dim);
+                blocks["kv_linear"] = std::make_shared<Linear>(context_dim, 2 * dim);
+            }
+            blocks["proj"] = std::make_shared<Linear>(dim, dim);
+        }
+
+        ggml_tensor* forward(GGMLRunnerContext* ctx, ggml_tensor* x, ggml_tensor* context, ggml_tensor* mask = nullptr) {
+            std::vector<ggml_tensor*> qkv;
+            if (self_attention) {
+                auto projected = std::dynamic_pointer_cast<Linear>(blocks["qkv"])->forward(ctx, x);
+                qkv            = ggml_ext_chunk(ctx->ggml_ctx, projected, 3, 0);
+            } else {
+                auto q     = std::dynamic_pointer_cast<Linear>(blocks["q_linear"])->forward(ctx, x);
+                auto kv    = std::dynamic_pointer_cast<Linear>(blocks["kv_linear"])->forward(ctx, context);
+                auto parts = ggml_ext_chunk(ctx->ggml_ctx, kv, 2, 0);
+                qkv        = {q, parts[0], parts[1]};
+            }
+            auto out = ggml_ext_attention_ext(ctx, qkv[0], qkv[1], qkv[2], num_heads, mask, false, ctx->flash_attn_enabled);
+            return std::dynamic_pointer_cast<Linear>(blocks["proj"])->forward(ctx, out);
+        }
+    };
+
+    class PixArtBlock : public GGMLBlock {
+        int64_t dim;
+
+        void init_params(ggml_context* ctx,
+                         const String2TensorStorage& tensor_storage_map = {},
+                         const std::string prefix                       = "") override {
+            ggml_type wtype             = get_type(prefix + "scale_shift_table", tensor_storage_map, GGML_TYPE_F32);
+            params["scale_shift_table"] = ggml_new_tensor_2d(ctx, wtype, dim, 6);
+        }
+
+    public:
+        PixArtBlock(int64_t dim, int64_t num_heads, int64_t context_dim, int64_t ffn_dim)
+            : dim(dim) {
+            blocks["attn"]       = std::make_shared<PixArtAttention>(dim, num_heads, dim, true);
+            blocks["cross_attn"] = std::make_shared<PixArtAttention>(dim, num_heads, context_dim, false);
+            blocks["mlp.fc1"]    = std::make_shared<Linear>(dim, ffn_dim);
+            blocks["mlp.fc2"]    = std::make_shared<Linear>(ffn_dim, dim);
+        }
+
+        static ggml_tensor* norm(ggml_context* ctx, ggml_tensor* x) {
+            return ggml_norm(ctx, x, 1e-6f);
+        }
+
+        ggml_tensor* forward(GGMLRunnerContext* ctx, ggml_tensor* x, ggml_tensor* mod, ggml_tensor* context, ggml_tensor* context_mask) {
+            // x: [N, n_token, dim]
+            // mod: [N, 6 * dim], shared adaLN-single output
+            int64_t N = x->ne[2];
+
+            auto table = params["scale_shift_table"];
+            if (table->type != GGML_TYPE_F32) {
+                table = ggml_cast(ctx->ggml_ctx, table, GGML_TYPE_F32);
+            }
+            table   = ggml_reshape_3d(ctx->ggml_ctx, table, dim, 6, 1);
+            auto m  = ggml_add(ctx->ggml_ctx, ggml_reshape_3d(ctx->ggml_ctx, mod, dim, 6, N), table);
+            auto mv = ggml_ext_chunk(ctx->ggml_ctx, ggml_reshape_2d(ctx->ggml_ctx, ggml_ext_cont(ctx->ggml_ctx, m), dim * 6, N), 6, 0);
+
+            auto attn1 = std::dynamic_pointer_cast<PixArtAttention>(blocks["attn"]);
+            auto attn2 = std::dynamic_pointer_cast<PixArtAttention>(blocks["cross_attn"]);
+            auto proj  = std::dynamic_pointer_cast<Linear>(blocks["mlp.fc1"]);
+            auto fc2   = std::dynamic_pointer_cast<Linear>(blocks["mlp.fc2"]);
+
+            auto gate = [&](ggml_tensor* y, ggml_tensor* g) {
+                g = ggml_reshape_3d(ctx->ggml_ctx, g, dim, 1, N);
+                return ggml_add(ctx->ggml_ctx, x, ggml_mul(ctx->ggml_ctx, y, g));
+            };
+
+            auto h = modulate(ctx->ggml_ctx, norm(ctx->ggml_ctx, x), mv[0], mv[1]);
+            x      = gate(attn1->forward(ctx, h, h), mv[2]);
+            // ada_norm_single: no norm before cross-attention (PixArtMS.py)
+            x = ggml_add(ctx->ggml_ctx, x, attn2->forward(ctx, x, context, context_mask));
+            h = modulate(ctx->ggml_ctx, norm(ctx->ggml_ctx, x), mv[3], mv[4]);
+            h = proj->forward(ctx, h);
+            h = ggml_ext_gelu(ctx->ggml_ctx, h, true);
+            h = fc2->forward(ctx, h);
+            return gate(h, mv[5]);
+        }
+    };
+
+    class PixArtModel : public GGMLBlock {
+        PixArtConfig config;
+
+        void init_params(ggml_context* ctx,
+                         const String2TensorStorage& tensor_storage_map = {},
+                         const std::string prefix                       = "") override {
+            ggml_type wtype                         = get_type(prefix + "final_layer.scale_shift_table", tensor_storage_map, GGML_TYPE_F32);
+            params["final_layer.scale_shift_table"] = ggml_new_tensor_2d(ctx, wtype, config.hidden_size, 2);
+        }
+
+    public:
+        PixArtModel() = default;
+        PixArtModel(const PixArtConfig& config)
+            : config(config) {
+            blocks["x_embedder.proj"]       = std::make_shared<Conv2d>(config.in_channels,
+                                                                 config.hidden_size,
+                                                                 std::pair<int, int>{static_cast<int>(config.patch_size), static_cast<int>(config.patch_size)},
+                                                                 std::pair<int, int>{static_cast<int>(config.patch_size), static_cast<int>(config.patch_size)});
+            blocks["t_embedder"]            = std::make_shared<PixArtTimestepEmbedding>(ADALN_EMBED_DIM, config.hidden_size);
+            blocks["t_block.1"]             = std::make_shared<Linear>(config.hidden_size, 6 * config.hidden_size);
+            blocks["y_embedder.y_proj.fc1"] = std::make_shared<Linear>(config.caption_channels, config.hidden_size);
+            blocks["y_embedder.y_proj.fc2"] = std::make_shared<Linear>(config.hidden_size, config.cross_attention_dim);
+            for (int i = 0; i < config.num_layers; ++i) {
+                blocks["blocks." + std::to_string(i)] =
+                    std::make_shared<PixArtBlock>(config.hidden_size, config.num_heads, config.cross_attention_dim, config.ffn_dim);
+            }
+            blocks["final_layer.norm_final"] = std::make_shared<LayerNorm>(config.hidden_size, 1e-6f, false);
+            blocks["final_layer.linear"]     = std::make_shared<Linear>(config.hidden_size,
+                                                                    config.patch_size * config.patch_size * config.out_channels);
+        }
+
+        ggml_tensor* forward(GGMLRunnerContext* ctx,
+                             ggml_tensor* x,
+                             ggml_tensor* timesteps,
+                             ggml_tensor* context,
+                             ggml_tensor* pos_embed,
+                             ggml_tensor* context_mask) {
+            // x: [N, C, H, W] latent, context: [N, n_ctx, caption_channels]
+            int64_t W  = x->ne[0];
+            int64_t H  = x->ne[1];
+            int64_t N  = x->ne[3];
+            int64_t p  = config.patch_size;
+            int64_t wp = W / p;
+            int64_t hp = H / p;
+
+            auto h = std::dynamic_pointer_cast<Conv2d>(blocks["x_embedder.proj"])->forward(ctx, x);  // [N, hidden, hp, wp]
+            h      = ggml_ext_cont(ctx->ggml_ctx, ggml_permute(ctx->ggml_ctx, h, 1, 2, 0, 3));       // [N, hp, wp, hidden] -> [N, hp*wp, hidden]
+            h      = ggml_reshape_3d(ctx->ggml_ctx, h, config.hidden_size, wp * hp, N);              // [N, hp*wp, hidden]
+            h      = ggml_add(ctx->ggml_ctx, h, pos_embed);
+
+            auto t   = ggml_ext_timestep_embedding(ctx->ggml_ctx, timesteps, ADALN_EMBED_DIM, 10000);
+            auto emb = std::dynamic_pointer_cast<PixArtTimestepEmbedding>(blocks["t_embedder"])->forward(ctx, t);
+
+            auto mod = std::dynamic_pointer_cast<Linear>(blocks["t_block.1"])
+                           ->forward(ctx, ggml_silu(ctx->ggml_ctx, emb));  // [N, 6 * hidden]
+
+            auto ctx_emb = std::dynamic_pointer_cast<Linear>(blocks["y_embedder.y_proj.fc1"])->forward(ctx, context);
+            ctx_emb      = ggml_ext_gelu(ctx->ggml_ctx, ctx_emb, true);
+            ctx_emb      = std::dynamic_pointer_cast<Linear>(blocks["y_embedder.y_proj.fc2"])->forward(ctx, ctx_emb);
+
+            for (int i = 0; i < config.num_layers; ++i) {
+                auto block = std::dynamic_pointer_cast<PixArtBlock>(blocks["blocks." + std::to_string(i)]);
+                h          = block->forward(ctx, h, mod, ctx_emb, context_mask);
+                sd::ggml_graph_cut::mark_graph_cut(h, "pixart.blocks." + std::to_string(i), "h");
+            }
+
+            // scale_shift_table + emb -> (shift, scale) for the affine-free final norm
+            auto tail_table = params["final_layer.scale_shift_table"];
+            if (tail_table->type != GGML_TYPE_F32) {
+                tail_table = ggml_cast(ctx->ggml_ctx, tail_table, GGML_TYPE_F32);
+            }
+            auto ss    = ggml_add(ctx->ggml_ctx,
+                                  ggml_reshape_3d(ctx->ggml_ctx, tail_table, config.hidden_size, 2, 1),
+                                  ggml_reshape_3d(ctx->ggml_ctx, emb, config.hidden_size, 1, N));  // [2, hidden, N]
+            auto parts = ggml_ext_chunk(ctx->ggml_ctx,
+                                        ggml_reshape_2d(ctx->ggml_ctx, ggml_ext_cont(ctx->ggml_ctx, ss), config.hidden_size * 2, N),
+                                        2, 0);
+            h          = std::dynamic_pointer_cast<LayerNorm>(blocks["final_layer.norm_final"])->forward(ctx, h);
+            h          = modulate(ctx->ggml_ctx, h, parts[0], parts[1]);
+            h          = std::dynamic_pointer_cast<Linear>(blocks["final_layer.linear"])->forward(ctx, h);  // [N, hp*wp, p*p*out_ch]
+            h          = DiT::unpatchify(ctx->ggml_ctx, h, hp, wp, static_cast<int>(p), static_cast<int>(p), false);
+            return h;  // [N, out_channels, H, W]
+        }
+    };
+
+    struct PixArtRunner : public DiffusionModelRunner {
+        PixArtConfig config;
+        PixArtModel model;
+        std::vector<float> pos_vec;
+
+        PixArtRunner(ggml_backend_t backend,
+                     const String2TensorStorage& tensor_storage_map      = {},
+                     const std::string prefix                            = "",
+                     std::shared_ptr<RunnerWeightManager> weight_manager = nullptr,
+                     const char* model_args                              = nullptr)
+            : DiffusionModelRunner(backend, prefix, weight_manager),
+              config(PixArtConfig::detect_from_weights(tensor_storage_map, prefix)) {
+            for (const auto& [key, value] : parse_key_value_args(model_args, "model arg")) {
+                if (key == "pixart_pos_embed_base_size") {
+                    int parsed = 0;
+                    if (parse_strict_int(value, parsed)) {
+                        config.pos_embed_base_size = parsed;
+                    } else {
+                        LOG_WARN("ignoring invalid PixArt model arg '%s=%s'", key.c_str(), value.c_str());
+                    }
+                } else if (key == "pixart_interpolation_scale") {
+                    float parsed = 0.f;
+                    if (parse_strict_float(value, parsed)) {
+                        config.interpolation_scale = parsed;
+                    } else {
+                        LOG_WARN("ignoring invalid PixArt model arg '%s=%s'", key.c_str(), value.c_str());
+                    }
+                }
+            }
+            model = PixArtModel(config);
+            model.init(params_ctx, tensor_storage_map, prefix);
+        }
+
+        std::string get_desc() override {
+            return "pixart";
+        }
+
+        void get_param_tensors(std::map<std::string, ggml_tensor*>& tensors, const std::string& prefix) override {
+            model.get_param_tensors(tensors, prefix);
+        }
+
+        ggml_cgraph* build_graph(const sd::Tensor<float>& x_tensor,
+                                 const sd::Tensor<float>& timesteps_tensor,
+                                 const sd::Tensor<float>& context_tensor,
+                                 const sd::Tensor<float>& mask_tensor) {
+            ggml_cgraph* gf        = new_graph_custom(PIXART_GRAPH_SIZE);
+            ggml_tensor* x         = make_input(x_tensor);
+            ggml_tensor* timesteps = make_input(timesteps_tensor);
+            GGML_ASSERT(x->ne[3] == 1);
+            GGML_ASSERT(!context_tensor.empty());
+            ggml_tensor* context = make_input(context_tensor);
+
+            ggml_tensor* context_mask = nullptr;
+            if (!mask_tensor.empty()) {
+                // additive attention bias over context tokens: 0 keep / -inf discard
+                context_mask = ggml_reshape_4d(compute_ctx, make_input(mask_tensor), mask_tensor.shape()[0], 1, 1, 1);
+            }
+
+            int64_t W  = x->ne[0];
+            int64_t H  = x->ne[1];
+            int64_t wp = W / config.patch_size;
+            int64_t hp = H / config.patch_size;
+
+            pos_vec  = gen_2d_sincos_pos_embed(config.hidden_size, hp, wp,
+                                               config.pos_embed_base_size, config.interpolation_scale);
+            auto pos = ggml_new_tensor_3d(compute_ctx, GGML_TYPE_F32, config.hidden_size, wp * hp, 1);
+            set_backend_tensor_data(pos, pos_vec.data());
+
+            auto runner_ctx  = get_context();
+            ggml_tensor* out = model.forward(&runner_ctx, x, timesteps, context, pos, context_mask);
+            // learn_sigma: keep the noise prediction half of the output channels
+            out = ggml_ext_slice(compute_ctx, out, 2, 0, config.in_channels);
+            ggml_build_forward_expand(gf, out);
+            return gf;
+        }
+
+        sd::Tensor<float> compute(int n_threads,
+                                  const sd::Tensor<float>& x,
+                                  const sd::Tensor<float>& timesteps,
+                                  const sd::Tensor<float>& context,
+                                  const sd::Tensor<float>& context_mask) {
+            auto get_graph = [&]() -> ggml_cgraph* {
+                return build_graph(x, timesteps, context, context_mask);
+            };
+            return restore_trailing_singleton_dims(GGMLRunner::compute(get_graph, n_threads, false), x.dim());
+        }
+
+        sd::Tensor<float> compute(int n_threads,
+                                  const DiffusionParams& diffusion_params) override {
+            GGML_ASSERT(diffusion_params.x != nullptr);
+            GGML_ASSERT(diffusion_params.timesteps != nullptr);
+            auto context     = tensor_or_empty(diffusion_params.context);
+            auto context_msk = tensor_or_empty(diffusion_params.y);
+            return compute(n_threads,
+                           *diffusion_params.x,
+                           *diffusion_params.timesteps,
+                           context,
+                           context_msk);
+        }
+    };
+}  // namespace PixArt
+
+#endif  // __SD_MODEL_DIFFUSION_PIXART_HPP__

src/model/vae/auto_encoder_kl.hpp

@@ -544,7 +544,7 @@ public:
                        const String2TensorStorage& tensor_storage_map = {},
                        const std::string& prefix                      = "")
         : version(version), decode_only(decode_only), use_video_decoder(use_video_decoder) {
-        if (sd_version_is_dit(version)) {
+        if (sd_version_is_dit(version) && version != VERSION_PIXART) {
             if (sd_version_uses_flux2_vae(version)) {
                 dd_config.z_channels = 32;
                 embed_dim            = 32;
@@ -678,7 +678,7 @@ struct AutoEncoderKL : public VAE {
         if (sd_version_is_sd1(version) || sd_version_is_sd2(version)) {
             scale_factor = 0.18215f;
             shift_factor = 0.f;
-        } else if (sd_version_is_sdxl(version)) {
+        } else if (sd_version_is_sdxl(version) || sd_version_is_pixart(version)) {
             scale_factor = 0.13025f;
             shift_factor = 0.f;
         } else if (sd_version_is_sd3(version)) {

src/model/vae/minimax_h3_vae.hpp

@@ -556,12 +556,18 @@ namespace MiniMaxH3VAE {
                                    tensor.shape()[3]});
         }
 
-        static sd_tiling_params_t h3_tiling(sd_tiling_params_t params) {
+        sd_tiling_params_t resolve_tiling_params(sd_tiling_params_t params) const override {
+            if (!params.enabled) {
+                params.target_overlap = 0.25f;
+            }
+            if (params.tile_size_w == 0 && params.rel_size_w == 0.f) {
+                params.tile_size_w = 256;
+            }
+            if (params.tile_size_h == 0 && params.rel_size_h == 0.f) {
+                params.tile_size_h = 256;
+            }
             params.enabled         = true;
             params.temporal_tiling = false;
-            params.tile_size_x     = 16;
-            params.tile_size_y     = 16;
-            params.target_overlap  = 0.25f;
             return params;
         }
 
@@ -605,7 +611,7 @@ namespace MiniMaxH3VAE {
                                  bool circular_x = false,
                                  bool circular_y = false) override {
             auto input  = ensure_video_shape(x);
-            auto tiling = h3_tiling(tiling_params);
+            auto tiling = resolve_tiling_params(tiling_params);
             if (input.shape()[2] == 1) {
                 auto encoded = VAE::encode(n_threads, input, tiling, circular_x, circular_y);
                 if (!encoded.empty() && encoded.shape()[2] > 1) {
@@ -646,7 +652,7 @@ namespace MiniMaxH3VAE {
                                  bool circular_y   = false,
                                  bool silent       = false) override {
             auto input  = ensure_video_shape(x);
-            auto tiling = h3_tiling(tiling_params);
+            auto tiling = resolve_tiling_params(tiling_params);
             if (input.shape()[2] == 1) {
                 auto decoded = VAE::decode(n_threads,
                                            input,

src/model/vae/tae.hpp

@@ -701,7 +701,7 @@ public:
         bool use_midblock_gn = false;
         taef2                = sd_version_uses_flux2_vae(version);
 
-        if (sd_version_is_dit(version)) {
+        if (sd_version_is_dit(version) && !sd_version_is_pixart(version)) {
             z_channels = 16;
         }
         if (taef2) {

src/model/vae/vae.hpp

@@ -1,6 +1,9 @@
 #ifndef __SD_MODEL_VAE_VAE_HPP__
 #define __SD_MODEL_VAE_VAE_HPP__
 
+#include <cmath>
+#include <limits>
+
 #include "core/tensor_ggml.hpp"
 #include "model/common/block.hpp"
 #include "model/vae/vae_tiling.hpp"
@@ -117,8 +120,8 @@ protected:
                                     int output_width,
                                     int output_height,
                                     int scale,
-                                    int p_tile_size_x,
-                                    int p_tile_size_y,
+                                    int p_tile_size_w,
+                                    int p_tile_size_h,
                                     float tile_overlap_factor,
                                     bool circular_x,
                                     bool circular_y,
@@ -138,17 +141,28 @@ protected:
             }
             return output_tile;
         };
-        return ::process_tiles_2d(input,
-                                  output_width,
-                                  output_height,
-                                  scale,
-                                  p_tile_size_x,
-                                  p_tile_size_y,
-                                  tile_overlap_factor,
-                                  circular_x,
-                                  circular_y,
-                                  on_processing,
-                                  silent);
+        const bool original_circular_x = circular_x_enabled;
+        const bool original_circular_y = circular_y_enabled;
+        const int64_t latent_width     = decode_graph ? input.shape()[0] : output_width;
+        const int64_t latent_height    = decode_graph ? input.shape()[1] : output_height;
+        circular_x                     = circular_x || original_circular_x;
+        circular_y                     = circular_y || original_circular_y;
+        // Full-width axes wrap in convolutions; split axes wrap between tiles.
+        set_circular_axes(circular_x && p_tile_size_w >= latent_width,
+                          circular_y && p_tile_size_h >= latent_height);
+        auto output = ::process_tiles_2d(input,
+                                         output_width,
+                                         output_height,
+                                         scale,
+                                         p_tile_size_w,
+                                         p_tile_size_h,
+                                         tile_overlap_factor,
+                                         circular_x && p_tile_size_w < latent_width,
+                                         circular_y && p_tile_size_h < latent_height,
+                                         on_processing,
+                                         silent);
+        set_circular_axes(original_circular_x, original_circular_y);
+        return output;
     }
 
 public:
@@ -178,33 +192,48 @@ public:
         return supports_temporal_tiling(VAETemporalDirection::DECODE);
     }
 
-    void get_tile_sizes(int& tile_size_x,
-                        int& tile_size_y,
+    virtual sd_tiling_params_t resolve_tiling_params(sd_tiling_params_t params) const {
+        return params;
+    }
+
+    bool get_tile_sizes(int& tile_size_w,
+                        int& tile_size_h,
                         float& tile_overlap,
                         const sd_tiling_params_t& params,
-                        int64_t latent_x,
-                        int64_t latent_y,
-                        float encoding_factor = 1.0f) {
-        tile_overlap       = std::max(std::min(params.target_overlap, 0.5f), 0.0f);
-        auto get_tile_size = [&](int requested_size, float factor, int64_t latent_size) {
-            const int default_tile_size  = 32;
-            const int min_tile_dimension = 4;
-            int tile_size                = default_tile_size;
-            // factor <= 1 means simple fraction of the latent dimension
-            // factor > 1 means number of tiles across that dimension
-            if (factor > 0.f) {
-                if (factor > 1.0)
-                    factor = 1 / (factor - factor * tile_overlap + tile_overlap);
-                tile_size = static_cast<int>(std::round(latent_size * factor));
-            } else if (requested_size >= min_tile_dimension) {
-                tile_size = requested_size;
+                        int64_t latent_w,
+                        int64_t latent_h) {
+        const auto tiling = resolve_tiling_params(params);
+        if (latent_w <= 0 || latent_h <= 0 ||
+            latent_w > std::numeric_limits<int>::max() || latent_h > std::numeric_limits<int>::max() ||
+            !std::isfinite(tiling.target_overlap)) {
+            LOG_ERROR("invalid VAE tiling dimensions or overlap");
+            return false;
+        }
+        const int scale_factor = get_scale_factor();
+        tile_overlap           = std::max(std::min(tiling.target_overlap, 0.5f), 0.0f);
+        auto get_tile_size     = [&](int requested_size, double factor, int64_t latent_size, int& tile_size) {
+            if (requested_size < 0 || !std::isfinite(factor) || factor < 0.0) {
+                LOG_ERROR("VAE tile sizes and relative sizes must be finite and non-negative");
+                return false;
             }
-            tile_size = static_cast<int>(tile_size * encoding_factor);
-            return std::max(std::min(tile_size, static_cast<int>(latent_size)), min_tile_dimension);
+            const int min_tile_dimension = std::min(4, static_cast<int>(latent_size));
+            double size                  = (requested_size > 0 ? requested_size : 256) / scale_factor;
+            if (factor > 0.0) {
+                if (factor > 1.0) {
+                    factor = 1.0 / (factor * (1.0 - tile_overlap) + tile_overlap);
+                }
+                size = std::floor(static_cast<double>(latent_size) * factor);
+            }
+            if (size < min_tile_dimension && (requested_size > 0 || factor > 0.0)) {
+                LOG_ERROR("VAE tile size must be at least %d image pixels on this axis", min_tile_dimension * scale_factor);
+                return false;
+            }
+            tile_size = static_cast<int>(std::min(static_cast<double>(latent_size), std::max<double>(min_tile_dimension, size)));
+            return true;
         };
 
-        tile_size_x = get_tile_size(params.tile_size_x, params.rel_size_x, latent_x);
-        tile_size_y = get_tile_size(params.tile_size_y, params.rel_size_y, latent_y);
+        return get_tile_size(tiling.tile_size_w, tiling.rel_size_w, latent_w, tile_size_w) &&
+               get_tile_size(tiling.tile_size_h, tiling.rel_size_h, latent_h, tile_size_h);
     }
 
     virtual sd::Tensor<float> encode(int n_threads,
@@ -213,6 +242,7 @@ public:
                                      bool circular_x = false,
                                      bool circular_y = false) {
         int64_t t0              = ggml_time_ms();
+        tiling_params           = resolve_tiling_params(tiling_params);
         sd::Tensor<float> input = x;
         sd::Tensor<float> output;
         if (scale_input) {
@@ -224,21 +254,19 @@ public:
             int64_t W              = input.shape()[0] / scale_factor;
             int64_t H              = input.shape()[1] / scale_factor;
             float tile_overlap;
-            int tile_size_x, tile_size_y;
-            // Image VAE encode is more sensitive to tile boundary context than decode.
-            // Keep the smaller legacy factor for video VAEs, but default image encode
-            // tiles to 64 latent pixels so a 512px SD image is encoded as one tile.
-            const float encode_tile_factor = sd_version_is_minimax_h3(version) ? 1.f : (sd_version_is_wan(version) || sd_version_is_hunyuan_video(version) || sd_version_is_ltxav(version)) ? 1.30539f
-                                                                                                                                                                                            : 2.0f;
-            get_tile_sizes(tile_size_x, tile_size_y, tile_overlap, tiling_params, W, H, encode_tile_factor);
-            LOG_VERBOSE("VAE Tile size: %dx%d", tile_size_x, tile_size_y);
+            int tile_size_w, tile_size_h;
+            if (!get_tile_sizes(tile_size_w, tile_size_h, tile_overlap, tiling_params, W, H)) {
+                return {};
+            }
+            LOG_VERBOSE("VAE encode tile size: %dx%d pixels (%dx%d latent)",
+                        tile_size_w * scale_factor, tile_size_h * scale_factor, tile_size_w, tile_size_h);
             output = tiled_compute(input,
                                    n_threads,
                                    static_cast<int>(W),
                                    static_cast<int>(H),
                                    scale_factor,
-                                   tile_size_x,
-                                   tile_size_y,
+                                   tile_size_w,
+                                   tile_size_h,
                                    tile_overlap,
                                    circular_x,
                                    circular_y,
@@ -271,6 +299,7 @@ public:
                                      bool circular_y   = false,
                                      bool silent       = false) {
         int64_t t0              = ggml_time_ms();
+        tiling_params           = resolve_tiling_params(tiling_params);
         sd::Tensor<float> input = x;
         sd::Tensor<float> output;
 
@@ -279,10 +308,13 @@ public:
             int64_t W              = input.shape()[0] * scale_factor;
             int64_t H              = input.shape()[1] * scale_factor;
             float tile_overlap;
-            int tile_size_x, tile_size_y;
-            get_tile_sizes(tile_size_x, tile_size_y, tile_overlap, tiling_params, input.shape()[0], input.shape()[1]);
+            int tile_size_w, tile_size_h;
+            if (!get_tile_sizes(tile_size_w, tile_size_h, tile_overlap, tiling_params, input.shape()[0], input.shape()[1])) {
+                return {};
+            }
             if (!silent) {
-                LOG_VERBOSE("VAE Tile size: %dx%d", tile_size_x, tile_size_y);
+                LOG_VERBOSE("VAE decode tile size: %dx%d pixels (%dx%d latent)",
+                            tile_size_w * scale_factor, tile_size_h * scale_factor, tile_size_w, tile_size_h);
             }
             output = tiled_compute(
                 input,
@@ -290,8 +322,8 @@ public:
                 static_cast<int>(W),
                 static_cast<int>(H),
                 scale_factor,
-                tile_size_x,
-                tile_size_y,
+                tile_size_w,
+                tile_size_h,
                 tile_overlap,
                 circular_x,
                 circular_y,

src/model_io/gguf_io.cpp

@@ -47,10 +47,14 @@ bool read_gguf_file(const std::string& file_path,
     gguf_context* ctx_gguf_ = nullptr;
     ggml_context* ctx_meta_ = nullptr;
 
-    ctx_gguf_ = gguf_init_from_file(file_path.c_str(), {true, &ctx_meta_});
+    GGUFReader gguf_reader;
+    bool probe_ok = gguf_reader.load(file_path);
+
+    if (!probe_ok || !gguf_reader.has_tensors_beyond_ggml_limits()) {
+        ctx_gguf_ = gguf_init_from_file(file_path.c_str(), {true, &ctx_meta_});
+    }
     if (!ctx_gguf_) {
-        GGUFReader gguf_reader;
-        if (!gguf_reader.load(file_path)) {
+        if (!probe_ok && !gguf_reader.load(file_path)) {
             set_error(error, "failed to open '" + file_path + "' with GGUFReader");
             return false;
         }

src/model_io/gguf_reader_ext.h

@@ -35,23 +35,72 @@ enum class GGUFMetadataType : uint32_t {
 class GGUFReader {
 private:
     std::vector<GGUFTensorInfo> tensors_;
+    bool has_wide_tensors_    = false;
+    uint64_t remaining_bytes_ = 0;
     size_t data_offset_;
     size_t alignment_ = 32;  // default alignment is 32
 
     template <typename T>
     bool safe_read(std::ifstream& fin, T& value) {
-        fin.read(reinterpret_cast<char*>(&value), sizeof(T));
-        return fin.good();
+        return safe_read(fin, reinterpret_cast<char*>(&value), sizeof(T));
     }
 
     bool safe_read(std::ifstream& fin, char* buffer, size_t size) {
+        if (size > remaining_bytes_)
+            return false;
         fin.read(buffer, size);
-        return fin.good();
+        if (!fin.good())
+            return false;
+        remaining_bytes_ -= size;
+        return true;
     }
 
-    bool safe_seek(std::ifstream& fin, std::streamoff offset, std::ios::seekdir dir) {
-        fin.seekg(offset, dir);
-        return fin.good();
+    bool safe_skip(std::ifstream& fin, uint64_t count, uint64_t element_size = 1) {
+        if (count > remaining_bytes_ / element_size)
+            return false;
+        uint64_t size = count * element_size;
+        fin.seekg(static_cast<std::streamoff>(size), std::ios::cur);
+        if (!fin.good())
+            return false;
+        remaining_bytes_ -= size;
+        return true;
+    }
+
+    bool skip_metadata_values(std::ifstream& fin, GGUFMetadataType type, uint64_t count) {
+        switch (type) {
+            case GGUFMetadataType::UINT8:
+            case GGUFMetadataType::INT8:
+            case GGUFMetadataType::BOOL:
+                return safe_skip(fin, count);
+
+            case GGUFMetadataType::UINT16:
+            case GGUFMetadataType::INT16:
+                return safe_skip(fin, count, 2);
+
+            case GGUFMetadataType::UINT32:
+            case GGUFMetadataType::INT32:
+            case GGUFMetadataType::FLOAT32:
+                return safe_skip(fin, count, 4);
+
+            case GGUFMetadataType::UINT64:
+            case GGUFMetadataType::INT64:
+            case GGUFMetadataType::FLOAT64:
+                return safe_skip(fin, count, 8);
+
+            case GGUFMetadataType::STRING:
+                if (count > remaining_bytes_ / sizeof(uint64_t))
+                    return false;
+                for (uint64_t i = 0; i < count; i++) {
+                    uint64_t len = 0;
+                    if (!safe_read(fin, len) || !safe_skip(fin, len))
+                        return false;
+                }
+                return true;
+
+            default:
+                LOG_ERROR("Unknown metadata type=%u", static_cast<uint32_t>(type));
+                return false;
+        }
     }
 
     bool read_metadata(std::ifstream& fin) {
@@ -84,52 +133,12 @@ private:
             return true;
         }
 
-        switch (static_cast<GGUFMetadataType>(type)) {
-            case GGUFMetadataType::UINT8:
-            case GGUFMetadataType::INT8:
-            case GGUFMetadataType::BOOL:
-                return safe_seek(fin, 1, std::ios::cur);
-
-            case GGUFMetadataType::UINT16:
-            case GGUFMetadataType::INT16:
-                return safe_seek(fin, 2, std::ios::cur);
-
-            case GGUFMetadataType::UINT32:
-            case GGUFMetadataType::INT32:
-            case GGUFMetadataType::FLOAT32:
-                return safe_seek(fin, 4, std::ios::cur);
-
-            case GGUFMetadataType::UINT64:
-            case GGUFMetadataType::INT64:
-            case GGUFMetadataType::FLOAT64:
-                return safe_seek(fin, 8, std::ios::cur);
-
-            case GGUFMetadataType::STRING: {
-                uint64_t len = 0;
-                if (!safe_read(fin, len))
-                    return false;
-                return safe_seek(fin, len, std::ios::cur);
-            }
-
-            case GGUFMetadataType::ARRAY: {
-                uint32_t elem_type = 0;
-                uint64_t len       = 0;
-                if (!safe_read(fin, elem_type))
-                    return false;
-                if (!safe_read(fin, len))
-                    return false;
-
-                for (uint64_t i = 0; i < len; i++) {
-                    if (!read_metadata(fin))
-                        return false;
-                }
-                return true;
-            }
-
-            default:
-                LOG_ERROR("Unknown metadata type=%u", type);
+        uint64_t count = 1;
+        if (type == static_cast<uint32_t>(GGUFMetadataType::ARRAY)) {
+            if (!safe_read(fin, type) || !safe_read(fin, count))
                 return false;
         }
+        return skip_metadata_values(fin, static_cast<GGUFMetadataType>(type), count);
     }
 
     GGUFTensorInfo read_tensor_info(std::ifstream& fin) {
@@ -154,6 +163,7 @@ private:
         }
 
         if (n_dims > GGML_MAX_DIMS) {
+            has_wide_tensors_ = true;
             for (uint32_t i = GGML_MAX_DIMS; i < n_dims; i++) {
                 info.shape[GGML_MAX_DIMS - 1] *= info.shape[i];  // stack to last dim;
             }
@@ -174,12 +184,20 @@ private:
 
 public:
     bool load(const std::string& file_path) {
-        std::ifstream fin(file_path, std::ios::binary);
+        std::ifstream fin(file_path, std::ios::binary | std::ios::ate);
         if (!fin) {
             LOG_ERROR("failed to open '%s'", file_path.c_str());
             return false;
         }
 
+        std::streamoff file_size = fin.tellg();
+        if (file_size < 0)
+            return false;
+        remaining_bytes_ = static_cast<uint64_t>(file_size);
+        fin.seekg(0, std::ios::beg);
+        if (!fin.good())
+            return false;
+
         // --- Header ---
         char magic[4];
         if (!safe_read(fin, magic, 4) || strncmp(magic, "GGUF", 4) != 0) {
@@ -228,6 +246,8 @@ public:
     }
 
     const std::vector<GGUFTensorInfo>& tensors() const { return tensors_; }
+
+    bool has_tensors_beyond_ggml_limits() const { return has_wide_tensors_; }
     size_t data_offset() const { return data_offset_; }
 };
 

src/model_loader.cpp

@@ -532,7 +532,18 @@ SDVersion ModelLoader::get_sd_version() const {
         if (tensor_storage.name.find("model.diffusion_model.layers.0.adaLN_sa_ln.weight") != std::string::npos) {
             return VERSION_ERNIE_IMAGE;
         }
+        if (tensor_storage.name.find("model.diffusion_model.t_block.1.weight") != std::string::npos &&
+            tensor_storage_map.find("model.diffusion_model.x_embedder.proj.weight") != tensor_storage_map.end() &&
+            tensor_storage_map.find("model.diffusion_model.audio_patchify_proj.weight") == tensor_storage_map.end()) {
+            return VERSION_PIXART;
+        }
         if (tensor_storage.name.find("model.diffusion_model.adaln_single.emb.timestep_embedder.linear_1.bias") != std::string::npos) {
+            // PixArt shares this timestep embedding with LTX-AV.
+            if (tensor_storage_map.find("model.diffusion_model.pos_embed.proj.weight") != tensor_storage_map.end() &&
+                tensor_storage_map.find("model.diffusion_model.adaln_single.linear.weight") != tensor_storage_map.end() &&
+                tensor_storage_map.find("model.diffusion_model.audio_patchify_proj.weight") == tensor_storage_map.end()) {
+                return VERSION_PIXART;
+            }
             return VERSION_LTXAV;
         }
         if (tensor_storage.name.find("model.diffusion_model.video_patch_proj.weight") != std::string::npos &&
@@ -1090,10 +1101,12 @@ bool ModelLoader::load_tensors(on_new_tensor_cb_t on_new_tensor_cb,
         if (tensors_to_process.empty()) {
             continue;
         }
-        LOG_VERBOSE("loading %zu/%zu tensors from %s",
-                    tensors_to_process.size(),
-                    file_tensors.size(),
-                    file_path.c_str());
+        if (log_progress) {
+            LOG_VERBOSE("loading %zu/%zu tensors from %s",
+                        tensors_to_process.size(),
+                        file_tensors.size(),
+                        file_path.c_str());
+        }
 
         bool is_zip = fdata.is_zip;
 
@@ -1597,6 +1610,9 @@ bool ModelLoader::tensor_should_be_converted(const TensorStorage& tensor_storage
             // Pass, do not convert. For Unet
         } else if (contains(name, "embedding")) {
             // Pass, do not convert embedding
+        } else if (contains(name, "scale_shift_table")) {
+            // Pass, do not convert. adaLN modulation tables (PixArt, LTXV) are sliced
+            // element-wise, which is invalid on quantized block layouts.
         } else if (ends_with(name, "_pad_token")) {
             // Pass, do not convert. LLaDA-Image stores its pad tokens far outside the f16
             // range, so any format with an f16 scale or payload turns them into inf.

src/model_manager.cpp

@@ -246,17 +246,13 @@ bool ModelManager::register_param_tensors(ModelComponent component,
         }
         ggml_set_name(tensor, name.c_str());
 
-        auto state            = std::make_unique<TensorState>();
-        state->name           = name;
-        state->tensor         = tensor;
-        state->component      = component;
-        state->source_file    = source_file;
-        state->source_version = source_version;
-        auto source           = sources.find(name);
-        if (source != sources.end()) {
-            state->source     = source->second;
-            state->has_source = true;
-        }
+        auto state             = std::make_unique<TensorState>();
+        state->name            = name;
+        state->tensor          = tensor;
+        state->component       = component;
+        state->source_file     = source_file;
+        state->source_version  = source_version;
+        state->sources         = find_tensor_sources(*state, sources);
         state->residency_mode  = residency_mode;
         state->compute_backend = compute_backend;
         state->params_backend  = params_backend;
@@ -757,12 +753,33 @@ bool ModelManager::validate_tensor(const TensorState& state) const {
         return true;
     }
 
-    if (!state.has_source) {
+    if (state.sources.empty()) {
         LOG_ERROR("%s tensor '%s' not in model metadata", model_component_name(state.component), state.name.c_str());
         return false;
     }
 
-    const TensorStorage& tensor_storage = state.source;
+    TensorStorage tensor_storage = state.sources.front();
+    if (state.sources.size() > 1) {
+        const int dim = tensor_storage.n_dims - 1;
+        if (dim < 0 || dim >= GGML_MAX_DIMS) {
+            return false;
+        }
+        tensor_storage.ne[dim] = 0;
+        for (const auto& part : state.sources) {
+            if (part.n_dims != tensor_storage.n_dims || part.ne[dim] < 0 ||
+                part.ne[dim] > state.tensor->ne[dim] - tensor_storage.ne[dim]) {
+                LOG_ERROR("invalid tensor part '%s' for '%s'", part.name.c_str(), state.name.c_str());
+                return false;
+            }
+            for (int i = 0; i < GGML_MAX_DIMS; ++i) {
+                if (i != dim && part.ne[i] != tensor_storage.ne[i]) {
+                    LOG_ERROR("incompatible tensor part '%s' for '%s'", part.name.c_str(), state.name.c_str());
+                    return false;
+                }
+            }
+            tensor_storage.ne[dim] += part.ne[dim];
+        }
+    }
     if (state.tensor->ne[0] != tensor_storage.ne[0] ||
         state.tensor->ne[1] != tensor_storage.ne[1] ||
         state.tensor->ne[2] != tensor_storage.ne[2] ||
@@ -831,7 +848,7 @@ bool ModelManager::mmap_params(const std::vector<TensorState*>& states,
 }
 
 bool ModelManager::can_mmap_storage(const TensorState& state) const {
-    if (state.source_file != 0 || !enable_mmap_ || state.residency_mode != ResidencyMode::ParamBackend) {
+    if (state.sources.size() > 1 || state.source_file != 0 || !enable_mmap_ || state.residency_mode != ResidencyMode::ParamBackend) {
         return false;
     }
     if (state.compute_backend == nullptr || state.params_backend == nullptr) {
@@ -941,6 +958,62 @@ bool ModelManager::alloc_params_buffers(const std::vector<TensorState*>& states,
     return true;
 }
 
+bool ModelManager::load_tensor_parts(TensorState& state) {
+    auto ctx = std::unique_ptr<ggml_context, decltype(&ggml_free)>(
+        ggml_init({state.sources.size() * ggml_tensor_overhead(), nullptr, true}), ggml_free);
+    if (!ctx) {
+        return false;
+    }
+    const size_t size = ggml_nbytes(state.tensor);
+    std::vector<uint8_t> buffer;
+    void* data = state.tensor->data;
+    if (!ggml_backend_buffer_is_host(state.tensor->buffer)) {
+        buffer.resize(size);
+        data = buffer.data();
+    }
+    std::map<std::string, ggml_tensor*> parts;
+    std::set<std::string> names;
+    size_t offset = 0;
+    for (const auto& source : state.sources) {
+        auto part              = ggml_new_tensor(ctx.get(), state.tensor->type, source.n_dims, source.ne);
+        const size_t part_size = ggml_nbytes(part);
+        if (part_size > size - offset) {
+            return false;
+        }
+        part->data         = static_cast<uint8_t*>(data) + offset;
+        parts[source.name] = part;
+        names.insert(source.name);
+        offset += part_size;
+    }
+    if (offset != size) {
+        return false;
+    }
+    std::set<std::string> loaded;
+    std::mutex mutex;
+    auto callback = [&](const TensorStorage& source, ggml_tensor** dst) {
+        *dst      = nullptr;
+        auto part = parts.find(source.name);
+        if (part != parts.end()) {
+            *dst = part->second;
+            std::lock_guard<std::mutex> lock(mutex);
+            loaded.insert(source.name);
+        }
+        return true;
+    };
+    const bool success = state.source_file == 0
+                             ? model_loader_.load_tensors(callback, enable_mmap_, &names, false)
+                             : model_loader_.load_file_tensors(state.source_file, state.source_version, callback, names, enable_mmap_);
+    if (!success || loaded != names) {
+        return false;
+    }
+    if (!buffer.empty()) {
+        // Upload the assembled tensor once, including for row-split backend buffers.
+        ggml_backend_tensor_set(state.tensor, buffer.data(), 0, size);
+    }
+    state.loaded_to_params_backend = true;
+    return true;
+}
+
 bool ModelManager::load_tensors(const std::vector<TensorState*>& states) {
     using ReadGroup = std::pair<ModelLoader::FileId, SDVersion>;
     using ReadBatch = std::map<std::string, std::vector<TensorState*>>;
@@ -948,6 +1021,12 @@ bool ModelManager::load_tensors(const std::vector<TensorState*>& states) {
     for (auto* state : states) {
         if (state == nullptr)
             continue;
+        if (state->sources.size() > 1) {
+            if (!load_tensor_parts(*state)) {
+                return false;
+            }
+            continue;
+        }
         auto& batches = groups[{state->source_file, state->source_version}];
         // The loader supplies one destination per name; only conflicting types need another batch.
         auto batch = std::find_if(batches.begin(), batches.end(), [&](const ReadBatch& candidate) {

src/model_manager.h

@@ -38,8 +38,7 @@ private:
         std::string name;
         ggml_tensor* tensor      = nullptr;
         ModelComponent component = ModelComponent::Count;
-        TensorStorage source;
-        bool has_source                 = false;
+        std::vector<TensorStorage> sources;
         ModelLoader::FileId source_file = 0;
         SDVersion source_version        = VERSION_COUNT;
 
@@ -138,6 +137,8 @@ private:
     bool apply_loras_to_params(const std::vector<TensorState*>& states);
     bool mmap_params(const std::vector<TensorState*>& states,
                      std::vector<ParamsStorageBlock*>& created_storage_blocks);
+    static std::vector<TensorStorage> find_tensor_sources(const TensorState& state, const String2TensorStorage& sources);
+    bool load_tensor_parts(TensorState& state);
     bool can_mmap_storage(const TensorState& state) const;
     bool alloc_params_buffers(const std::vector<TensorState*>& states,
                               std::vector<ParamsStorageBlock*>& created_storage_blocks);

src/model_manager_files.cpp

@@ -15,6 +15,26 @@ static bool same_tensor_source(const TensorStorage& a, const TensorStorage& b) {
            a.int8_convrot_group_size == b.int8_convrot_group_size;
 }
 
+std::vector<TensorStorage> ModelManager::find_tensor_sources(const TensorState& state, const String2TensorStorage& sources) {
+    auto first = sources.find(state.name);
+    if (first == sources.end()) {
+        return {};
+    }
+    std::vector<TensorStorage> result{first->second};
+    if (state.component == ModelComponent::LoRA ||
+        std::equal(first->second.ne, first->second.ne + GGML_MAX_DIMS, state.tensor->ne)) {
+        return result;
+    }
+    for (size_t i = 1;; ++i) {
+        auto part = sources.find(state.name + "." + std::to_string(i));
+        if (part == sources.end()) {
+            break;
+        }
+        result.push_back(part->second);
+    }
+    return result;
+}
+
 void ModelManager::invalidate_sources(const std::unordered_set<TensorState*>& states) {
     auto affected = states;
     for (const auto& block : params_storage_blocks_) {
@@ -76,20 +96,16 @@ bool ModelManager::set_loader(ModelLoader loader) {
     }
     std::unordered_set<TensorState*> changed;
     for (const auto& state : tensor_states_) {
-        const auto& sources = sources_for(*state);
-        auto source         = sources.find(state->name);
-        const bool found    = source != sources.end();
-        if (found != state->has_source || (found && !same_tensor_source(state->source, source->second)) ||
+        const auto sources = find_tensor_sources(*state, sources_for(*state));
+        if (sources.size() != state->sources.size() ||
+            !std::equal(sources.begin(), sources.end(), state->sources.begin(), same_tensor_source) ||
             (lora_changed && state->component != ModelComponent::LoRA && state->applied_lora_epoch != UINT64_MAX)) {
             changed.insert(state.get());
         }
     }
     invalidate_sources(changed);
     for (auto* state : changed) {
-        const auto& sources = sources_for(*state);
-        auto source         = sources.find(state->name);
-        state->has_source   = source != sources.end();
-        state->source       = state->has_source ? source->second : TensorStorage{};
+        state->sources = find_tensor_sources(*state, sources_for(*state));
     }
     if (lora_changed) {
         ++current_lora_epoch_;
@@ -134,9 +150,8 @@ ModelLoader::FileVersions ModelManager::source_versions(const std::set<ModelComp
             versions[state->source_file] = loader.file_revision(state->source_file);
             continue;
         }
-        auto source = sources.find(state->name);
-        if (source != sources.end()) {
-            versions[source->second.file_id] = source->second.file_revision;
+        for (const auto& source : find_tensor_sources(*state, sources)) {
+            versions[source.file_id] = source.file_revision;
         }
     }
     return versions;

src/name_conversion.cpp

@@ -932,6 +932,68 @@ static bool is_diffusers_controlnet_name(const std::string& name) {
     return false;
 }
 
+static std::string convert_diffusers_dit_to_original_pixart(std::string name) {
+    static const std::vector<std::pair<std::string, std::string>> prefix_map = {
+        {"pos_embed.proj.", "x_embedder.proj."},
+        {"adaln_single.emb.timestep_embedder.linear_1.", "t_embedder.mlp.0."},
+        {"adaln_single.emb.timestep_embedder.linear_2.", "t_embedder.mlp.2."},
+        {"adaln_single.emb.resolution_embedder.linear_1.", "csize_embedder.mlp.0."},
+        {"adaln_single.emb.resolution_embedder.linear_2.", "csize_embedder.mlp.2."},
+        {"adaln_single.emb.aspect_ratio_embedder.linear_1.", "ar_embedder.mlp.0."},
+        {"adaln_single.emb.aspect_ratio_embedder.linear_2.", "ar_embedder.mlp.2."},
+        {"adaln_single.linear.", "t_block.1."},
+        {"caption_projection.linear_1.", "y_embedder.y_proj.fc1."},
+        {"caption_projection.linear_2.", "y_embedder.y_proj.fc2."},
+        {"proj_out.", "final_layer.linear."},
+    };
+    for (const auto& entry : prefix_map) {
+        if (starts_with(name, entry.first)) {
+            return entry.second + name.substr(entry.first.size());
+        }
+    }
+    if (name == "scale_shift_table") {
+        return "final_layer.scale_shift_table";
+    }
+    const std::string block_prefix = "transformer_blocks.";
+    if (!starts_with(name, block_prefix)) {
+        return name;
+    }
+    const size_t block_end = name.find('.', block_prefix.size());
+    if (block_end == std::string::npos) {
+        return name;
+    }
+    const std::string prefix                                                = "blocks." + name.substr(block_prefix.size(), block_end - block_prefix.size()) + ".";
+    name                                                                    = name.substr(block_end + 1);
+    static const std::vector<std::pair<std::string, std::string>> block_map = {
+        {"attn1.to_q.", "attn.qkv."},
+        {"attn1.to_out.0.", "attn.proj."},
+        {"attn2.to_q.", "cross_attn.q_linear."},
+        {"attn2.to_k.", "cross_attn.kv_linear."},
+        {"attn2.to_out.0.", "cross_attn.proj."},
+        {"ff.net.0.proj.", "mlp.fc1."},
+        {"ff.net.2.", "mlp.fc2."},
+    };
+    for (const auto& entry : block_map) {
+        if (starts_with(name, entry.first)) {
+            return prefix + entry.second + name.substr(entry.first.size());
+        }
+    }
+    static const std::vector<std::pair<std::string, std::string>> part_map = {
+        {"attn1.to_k.weight", "attn.qkv.weight.1"},
+        {"attn1.to_k.bias", "attn.qkv.bias.1"},
+        {"attn1.to_v.weight", "attn.qkv.weight.2"},
+        {"attn1.to_v.bias", "attn.qkv.bias.2"},
+        {"attn2.to_v.weight", "cross_attn.kv_linear.weight.1"},
+        {"attn2.to_v.bias", "cross_attn.kv_linear.bias.1"},
+    };
+    for (const auto& entry : part_map) {
+        if (name == entry.first || starts_with(name, entry.first + ".")) {
+            return prefix + entry.second + name.substr(entry.first.size());
+        }
+    }
+    return prefix + name;
+}
+
 std::string convert_diffusion_model_name(std::string name, std::string prefix, SDVersion version) {
     if (sd_version_is_sd1(version) || sd_version_is_sd2(version)) {
         name = convert_diffusers_unet_to_original_sd1(name);
@@ -951,6 +1013,8 @@ std::string convert_diffusion_model_name(std::string name, std::string prefix, S
         name = convert_other_dit_to_original_anima(name);
     } else if (sd_version_is_krea2(version)) {
         name = convert_diffusers_dit_to_original_krea2(name);
+    } else if (sd_version_is_pixart(version)) {
+        name = convert_diffusers_dit_to_original_pixart(name);
     }
     return name;
 }

src/pipeline/diffusion_engine.cpp

@@ -105,6 +105,7 @@ const char* model_version_to_str[] = {
     "SenseNova U1.5",
     "LLaDA-Image",
     "ESRGAN",
+    "PixArt",
 };
 
 static_assert(VERSION_COUNT == sizeof(model_version_to_str) / sizeof(model_version_to_str[0]),
@@ -125,6 +126,18 @@ void calculate_alphas_cumprod(float* alphas_cumprod,
     }
 }
 
+void calculate_alphas_cumprod_linear_beta(float* alphas_cumprod,
+                                          float beta_start,
+                                          float beta_end,
+                                          int timesteps = TIMESTEPS) {
+    float product = 1.0f;
+    for (int i = 0; i < timesteps; i++) {
+        float beta = beta_start + (beta_end - beta_start) * ((float)i / (timesteps - 1));
+        product *= 1.0f - beta;
+        alphas_cumprod[i] = product;
+    }
+}
+
 template <typename T, typename = void>
 struct has_set_runtime_backends : std::false_type {};
 template <typename T>
@@ -666,6 +679,10 @@ void StableDiffusionGGML::refresh_compvis_denoiser_sigmas() {
     std::vector<float> alphas_cumprod(TIMESTEPS);
     if (file_alphas_cumprod.size() == TIMESTEPS) {
         alphas_cumprod = file_alphas_cumprod;
+    } else if (sd_version_is_pixart(version)) {
+        // PixArt checkpoints train with a linear beta schedule (0.0001 -> 0.02)
+        // instead of the scaled_linear schedule used by SD1.x/SDXL.
+        calculate_alphas_cumprod_linear_beta(alphas_cumprod.data(), 0.0001f, 0.02f);
     } else {
         calculate_alphas_cumprod(alphas_cumprod.data());
     }
@@ -2731,7 +2748,7 @@ int StableDiffusionGGML::get_diffusion_model_down_factor() {
     if (sd_version_is_dit(version)) {
         if (sd_version_is_sensenova_u1(version)) {
             down_factor = 32;
-        } else if (version == VERSION_QWEN_IMAGE_2_1 || sd_version_is_wan(version) || sd_version_is_lingbot_video(version) || sd_version_is_minimax_h3(version)) {
+        } else if (version == VERSION_QWEN_IMAGE_2_1 || sd_version_is_wan(version) || sd_version_is_lingbot_video(version) || sd_version_is_minimax_h3(version) || sd_version_is_pixart(version)) {
             down_factor = 2;
         } else {
             down_factor = 1;
@@ -2769,6 +2786,8 @@ int StableDiffusionGGML::get_latent_channel() {
             latent_channel = 128;
         } else if (sd_version_is_mage_flow(version)) {
             latent_channel = 128;
+        } else if (sd_version_is_pixart(version)) {
+            latent_channel = 4;
         } else {
             latent_channel = 16;
         }
@@ -2864,14 +2883,26 @@ sd::Tensor<float> StableDiffusionGGML::decode_first_stage(const sd::Tensor<float
         return sd::ops::clamp((x + 1.f) * 0.5f, 0.0f, 1.0f);
     }
     auto latents                      = first_stage_model->diffusion_to_vae_latents(x);
-    auto decoded                      = first_stage_model->decode(n_threads, latents, vae_tiling_params, decode_video, circular_x, circular_y);
-    const bool prefer_temporal_tiling = decode_video && first_stage_model->can_temporal_tile_decode();
-    while (decoded.empty() &&
-           sd::backend_fit::prepare_vae_decode_retry_tiling(vae_tiling_params, prefer_temporal_tiling,
-                                                            first_stage_model->last_compute_status())) {
-        decoded = first_stage_model->decode(n_threads, latents, vae_tiling_params, decode_video, circular_x, circular_y);
+    auto tiling_params                = first_stage_model->resolve_tiling_params(vae_tiling_params);
+    const bool prefer_temporal_tiling = decode_video && latents.dim() == 5 && latents.shape()[2] > 1 &&
+                                        first_stage_model->can_temporal_tile_decode();
+    for (;;) {
+        int tile_size_w = static_cast<int>(latents.shape()[0]);
+        int tile_size_h = static_cast<int>(latents.shape()[1]);
+        float tile_overlap;
+        if (tiling_params.enabled &&
+            !first_stage_model->get_tile_sizes(tile_size_w, tile_size_h, tile_overlap, tiling_params,
+                                               latents.shape()[0], latents.shape()[1])) {
+            return {};
+        }
+        auto decoded = first_stage_model->decode(n_threads, latents, tiling_params, decode_video, circular_x, circular_y);
+        if (!decoded.empty() ||
+            !sd::backend_fit::prepare_vae_decode_retry_tiling(tiling_params, prefer_temporal_tiling,
+                                                              first_stage_model->last_compute_status(),
+                                                              tile_size_w, tile_size_h, first_stage_model->get_scale_factor())) {
+            return decoded;
+        }
     }
-    return decoded;
 }
 
 sd::Tensor<float> StableDiffusionGGML::normalize_ltx_video_latents(const sd::Tensor<float>& x) {

src/pipeline/image.cpp

@@ -35,19 +35,21 @@ namespace sd::pipeline {
             return original_axes;
         }
 
-        int tile_size_x, tile_size_y;
+        int tile_size_w, tile_size_h;
         float overlap;
-        int latent_size_x = request.width / request.vae_scale_factor;
-        int latent_size_y = request.height / request.vae_scale_factor;
-        sd->first_stage_model->get_tile_sizes(tile_size_x,
-                                              tile_size_y,
-                                              overlap,
-                                              sd_img_gen_params->vae_tiling_params,
-                                              latent_size_x,
-                                              latent_size_y);
+        int latent_size_w = request.width / request.vae_scale_factor;
+        int latent_size_h = request.height / request.vae_scale_factor;
+        if (!sd->first_stage_model->get_tile_sizes(tile_size_w,
+                                                   tile_size_h,
+                                                   overlap,
+                                                   sd_img_gen_params->vae_tiling_params,
+                                                   latent_size_w,
+                                                   latent_size_h)) {
+            return original_axes;
+        }
 
-        sd->circular_x = sd->circular_x && (tile_size_x >= latent_size_x);
-        sd->circular_y = sd->circular_y && (tile_size_y >= latent_size_y);
+        sd->circular_x = sd->circular_x && (tile_size_w >= latent_size_w);
+        sd->circular_y = sd->circular_y && (tile_size_h >= latent_size_h);
 
         if (sd->first_stage_model) {
             sd->first_stage_model->set_circular_axes(sd->circular_x, sd->circular_y);
@@ -56,8 +58,8 @@ namespace sd::pipeline {
             sd->preview_vae->set_circular_axes(sd->circular_x, sd->circular_y);
         }
 
-        sd->circular_x = original_axes.circular_x && (tile_size_x < latent_size_x);
-        sd->circular_y = original_axes.circular_y && (tile_size_y < latent_size_y);
+        sd->circular_x = original_axes.circular_x && (tile_size_w < latent_size_w);
+        sd->circular_y = original_axes.circular_y && (tile_size_h < latent_size_h);
 
         return original_axes;
     }

src/pipeline/model_builders.cpp

@@ -1,5 +1,6 @@
 #include "model_builders.h"
 
+#include <cmath>
 #include <cstring>
 #include <utility>
 
@@ -28,6 +29,7 @@
 #include "model/diffusion/mmdit.hpp"
 #include "model/diffusion/model.hpp"
 #include "model/diffusion/pid.hpp"
+#include "model/diffusion/pixart.hpp"
 #include "model/diffusion/qwen_image.hpp"
 #include "model/diffusion/qwen_image_2_1.hpp"
 #include "model/diffusion/sensenova_u1.h"
@@ -301,6 +303,19 @@ namespace sd::model_builders {
                                                                            weight_manager,
                                                                            sd_ctx_params->model_args);
             }
+        } else if (version == VERSION_PIXART) {
+            result.conditioner = std::make_shared<T5CLIPEmbedder>(ctx.backends.runtime_backend(SDBackendModule::TE),
+                                                                  tensor_storage_map,
+                                                                  true,
+                                                                  0,
+                                                                  false,
+                                                                  weight_manager,
+                                                                  sd_ctx_params->model_args);
+            result.diffusion   = std::make_shared<PixArt::PixArtRunner>(ctx.backends.runtime_backend(SDBackendModule::DIFFUSION),
+                                                                      tensor_storage_map,
+                                                                      "model.diffusion_model",
+                                                                      weight_manager,
+                                                                      sd_ctx_params->model_args);
         } else if (sd_version_is_mage_flow(version)) {
             result.conditioner = std::make_shared<LLMEmbedder>(ctx.backends.runtime_backend(SDBackendModule::TE),
                                                                tensor_storage_map,
@@ -562,6 +577,23 @@ namespace sd::model_builders {
                                                              false,
                                                              vae_version,
                                                              weight_manager);
+                if (sd_version_is_pixart(version)) {
+                    // Alpha-512 and Sigma share tensor layouts; Alpha-512 needs an explicit scale override.
+                    if (tensor_storage_map.count("model.diffusion_model.csize_embedder.mlp.0.weight") != 0) {
+                        model->scale_factor = 0.18215f;
+                    }
+                    for (const auto& [key, value] : parse_key_value_args(sd_ctx_params->model_args, "model arg")) {
+                        if (key == "pixart_vae_scale_factor") {
+                            float parsed = 0.f;
+                            if (parse_strict_float(value, parsed) && std::isfinite(parsed) && parsed > 0.f) {
+                                model->scale_factor = parsed;
+                            } else {
+                                LOG_WARN("ignoring invalid PixArt model arg '%s=%s'", key.c_str(), value.c_str());
+                            }
+                        }
+                    }
+                    LOG_VERBOSE("pixart: VAE scale factor = %.5f", model->scale_factor);
+                }
                 if (sd_version_is_sdxl(version) &&
                     (strlen(SAFE_STR(sd_ctx_params->vae_path)) == 0 || sd_ctx_params->force_sdxl_vae_conv_scale || options.external_vae_is_invalid)) {
                     float vae_conv_2d_scale = 1.f / 32.f;

src/runtime/tiling.cpp

@@ -142,8 +142,8 @@ sd::Tensor<float> process_tiles_2d(const sd::Tensor<float>& input,
                                    int output_width,
                                    int output_height,
                                    int scale,
-                                   int p_tile_size_x,
-                                   int p_tile_size_y,
+                                   int p_tile_size_w,
+                                   int p_tile_size_h,
                                    float tile_overlap_factor,
                                    bool circular_x,
                                    bool circular_y,
@@ -168,28 +168,28 @@ sd::Tensor<float> process_tiles_2d(const sd::Tensor<float>& input,
 
     int num_tiles_x;
     float tile_overlap_factor_x;
-    sd_tiling_calc_tiles(num_tiles_x, tile_overlap_factor_x, small_width, p_tile_size_x, tile_overlap_factor, circular_x);
+    sd_tiling_calc_tiles(num_tiles_x, tile_overlap_factor_x, small_width, p_tile_size_w, tile_overlap_factor, circular_x);
 
     int num_tiles_y;
     float tile_overlap_factor_y;
-    sd_tiling_calc_tiles(num_tiles_y, tile_overlap_factor_y, small_height, p_tile_size_y, tile_overlap_factor, circular_y);
+    sd_tiling_calc_tiles(num_tiles_y, tile_overlap_factor_y, small_height, p_tile_size_h, tile_overlap_factor, circular_y);
 
-    int tile_overlap_x     = static_cast<int32_t>(p_tile_size_x * tile_overlap_factor_x);
-    int non_tile_overlap_x = p_tile_size_x - tile_overlap_x;
-    int tile_overlap_y     = static_cast<int32_t>(p_tile_size_y * tile_overlap_factor_y);
-    int non_tile_overlap_y = p_tile_size_y - tile_overlap_y;
-    int tile_size_x        = p_tile_size_x < small_width ? p_tile_size_x : small_width;
-    int tile_size_y        = p_tile_size_y < small_height ? p_tile_size_y : small_height;
-    int input_tile_size_x  = tile_size_x;
-    int input_tile_size_y  = tile_size_y;
-    int output_tile_size_x = tile_size_x;
-    int output_tile_size_y = tile_size_y;
+    int tile_overlap_x     = static_cast<int32_t>(p_tile_size_w * tile_overlap_factor_x);
+    int non_tile_overlap_x = p_tile_size_w - tile_overlap_x;
+    int tile_overlap_y     = static_cast<int32_t>(p_tile_size_h * tile_overlap_factor_y);
+    int non_tile_overlap_y = p_tile_size_h - tile_overlap_y;
+    int tile_size_w        = p_tile_size_w < small_width ? p_tile_size_w : small_width;
+    int tile_size_h        = p_tile_size_h < small_height ? p_tile_size_h : small_height;
+    int input_tile_size_w  = tile_size_w;
+    int input_tile_size_h  = tile_size_h;
+    int output_tile_size_w = tile_size_w;
+    int output_tile_size_h = tile_size_h;
     if (decode) {
-        output_tile_size_x *= scale;
-        output_tile_size_y *= scale;
+        output_tile_size_w *= scale;
+        output_tile_size_h *= scale;
     } else {
-        input_tile_size_x *= scale;
-        input_tile_size_y *= scale;
+        input_tile_size_w *= scale;
+        input_tile_size_h *= scale;
     }
 
     int num_tiles   = num_tiles_x * num_tiles_y;
@@ -205,9 +205,9 @@ sd::Tensor<float> process_tiles_2d(const sd::Tensor<float>& input,
     }
     for (int y = 0; y < small_height && !last_y; y += non_tile_overlap_y) {
         int dy = 0;
-        if (!circular_y && y + tile_size_y >= small_height) {
+        if (!circular_y && y + tile_size_h >= small_height) {
             int original_y = y;
-            y              = small_height - tile_size_y;
+            y              = small_height - tile_size_h;
             dy             = original_y - y;
             if (decode) {
                 dy *= scale;
@@ -216,9 +216,9 @@ sd::Tensor<float> process_tiles_2d(const sd::Tensor<float>& input,
         }
         for (int x = 0; x < small_width && !last_x; x += non_tile_overlap_x) {
             int dx = 0;
-            if (!circular_x && x + tile_size_x >= small_width) {
+            if (!circular_x && x + tile_size_w >= small_width) {
                 int original_x = x;
-                x              = small_width - tile_size_x;
+                x              = small_width - tile_size_w;
                 dx             = original_x - x;
                 if (decode) {
                     dx *= scale;
@@ -235,12 +235,12 @@ sd::Tensor<float> process_tiles_2d(const sd::Tensor<float>& input,
             int overlap_y_out = decode ? tile_overlap_y * scale : tile_overlap_y;
 
             int64_t t1       = ggml_time_ms();
-            auto input_tile  = sd_tensor_split_2d(input, input_tile_size_x, input_tile_size_y, x_in, y_in);
+            auto input_tile  = sd_tensor_split_2d(input, input_tile_size_w, input_tile_size_h, x_in, y_in);
             auto output_tile = on_processing(input_tile);
             if (output_tile.empty()) {
                 return {};
             }
-            GGML_ASSERT(output_tile.shape()[0] == output_tile_size_x && output_tile.shape()[1] == output_tile_size_y);
+            GGML_ASSERT(output_tile.shape()[0] == output_tile_size_w && output_tile.shape()[1] == output_tile_size_h);
             if (output.empty()) {
                 std::vector<int64_t> output_shape = output_tile.shape();
                 output_shape[0]                   = output_width;

src/runtime/tiling.h

@@ -11,8 +11,8 @@ sd::Tensor<float> process_tiles_2d(const sd::Tensor<float>& input,
                                    int output_width,
                                    int output_height,
                                    int scale,
-                                   int p_tile_size_x,
-                                   int p_tile_size_y,
+                                   int p_tile_size_w,
+                                   int p_tile_size_h,
                                    float tile_overlap_factor,
                                    bool circular_x,
                                    bool circular_y,

src/tokenizers/t5_unigram_tokenizer.cpp

@@ -295,7 +295,13 @@ bool T5UniGramTokenizer::encode(const std::string& input, std::vector<int>& resu
     std::vector<int32_t> tokens;
     std::vector<std::string> token_strs;
     std::string normalized = normalize(input);
-    auto splited_texts     = split_with_special_tokens(normalized, special_tokens);
+    if (normalized.empty()) {
+        // HF reference tokenizers emit no pieces for empty input; pad_tokens
+        // still appends EOS so the sequence becomes [EOS] + padding.
+        result = std::move(tokens);
+        return true;
+    }
+    auto splited_texts = split_with_special_tokens(normalized, special_tokens);
     if (splited_texts.empty()) {
         splited_texts.push_back(normalized);  // for empty string
     }