diff --git a/studio/backend/core/inference/diffusion.py b/studio/backend/core/inference/diffusion.py
index 8f7291cffa..7bd7180b53 100644
--- a/studio/backend/core/inference/diffusion.py
+++ b/studio/backend/core/inference/diffusion.py
@@ -488,6 +488,16 @@ class DiffusionBackend:
                     )
             elif path_shaped:
                 raise FileNotFoundError(f"Local model path does not exist: {repo_id}")
+            elif repo_id.upper().endswith("-GGUF"):
+                # A remote "*-GGUF" id is a single-file GGUF repo, not a full diffusers
+                # pipeline: loading it as a pipeline passes the trusted-repo check, evicts
+                # chat, then fails in the background when from_pretrained finds no
+                # model_index.json. Reject the certain case here (no network round-trip)
+                # so the bad pick fails before the GPU handoff, as the route expects.
+                raise ValueError(
+                    f"'{repo_id}' is a single-file GGUF repo; load it with model_kind 'gguf' "
+                    f"and a .gguf filename, not as a full pipeline."
+                )
         return fam
 
     # ── Background load + progress ─────────────────────────────────────────
@@ -1348,7 +1358,14 @@ class DiffusionBackend:
         # reuse the resident modules AT THEIR LOADED dtype, which is the whole point of
         # from_pipe (component reuse, no reload, no extra VRAM).
         pipe = getattr(diffusers, class_name).from_pipe(state.pipe, torch_dtype = None)
-        self._aux_pipes[class_name] = pipe
+        # Only publish to the shared aux cache if THIS load is still current. from_pipe runs
+        # under _generate_lock but NOT _lock, so an unload()/superseding load can clear
+        # _aux_pipes and null _state while it builds; caching unconditionally would re-insert
+        # a wrapper over now-stale modules that a later same-workflow load would reuse (or
+        # keep the old VRAM pinned). This generation still uses the returned pipe.
+        with self._lock:
+            if self._state is state:
+                self._aux_pipes[class_name] = pipe
         return pipe
 
     @staticmethod
diff --git a/studio/backend/routes/inference.py b/studio/backend/routes/inference.py
index 084d892a07..30f35cb9de 100644
--- a/studio/backend/routes/inference.py
+++ b/studio/backend/routes/inference.py
@@ -11199,8 +11199,13 @@ async def generate_diffusion_image(
                     {
                         "prompt": request.prompt,
                         "negative_prompt": request.negative_prompt,
-                        "width": request.width,
-                        "height": request.height,
+                        # Persist the ACTUAL output size, not the request sliders: Transform/
+                        # Inpaint/Edit derive it from the uploaded image, Extend grows the
+                        # canvas, and Upscale resizes it, so request.width/height would record
+                        # (and later restore) the wrong dimensions for those workflows. For
+                        # plain txt2img the image size equals the sliders anyway.
+                        "width": getattr(image, "width", None) or request.width,
+                        "height": getattr(image, "height", None) or request.height,
                         "steps": request.steps,
                         "guidance": request.guidance,
                         "seed": seed,
diff --git a/studio/backend/tests/test_diffusion_backend.py b/studio/backend/tests/test_diffusion_backend.py
index d1cbf513d0..ce1ced8352 100644
--- a/studio/backend/tests/test_diffusion_backend.py
+++ b/studio/backend/tests/test_diffusion_backend.py
@@ -1461,6 +1461,11 @@ def test_validate_load_request(tmp_path):
         backend.validate_load_request(
             "unsloth/Qwen-Image-2512-FP8", gguf_filename = "q.gguf", model_kind = "single_file"
         )
+    # A remote "*-GGUF" repo loaded as a full pipeline (no single-file name) is a single-file
+    # GGUF repo, so from_pretrained would find no pipeline manifest and fail after chat is
+    # already evicted; reject it here before the GPU handoff.
+    with pytest.raises(ValueError, match = "GGUF"):
+        backend.validate_load_request("unsloth/Z-Image-Turbo-GGUF", model_kind = "pipeline")
     # A local path with a missing child fails here (before any GPU/network work).
     with pytest.raises(FileNotFoundError):
         backend.validate_load_request(
diff --git a/studio/install_sd_cpp_prebuilt.py b/studio/install_sd_cpp_prebuilt.py
index 193c5e4670..639e3a894d 100644
--- a/studio/install_sd_cpp_prebuilt.py
+++ b/studio/install_sd_cpp_prebuilt.py
@@ -262,6 +262,10 @@ def _maybe_fetch_windows_cudart(release: dict, chosen: str, target: Path) -> Non
     print(f"downloading CUDA runtime {cudart['name']} ...", flush = True)
     try:
         _download(cudart["browser_download_url"], dest)
+        # Verify integrity BEFORE extracting, like the main sd-cli archive: these DLLs are
+        # loaded into sd-cli.exe at runtime, so a corrupt/tampered runtime archive must be
+        # rejected rather than extracted next to the binary.
+        _verify_sha256(dest, cudart.get("digest"))
         with zipfile.ZipFile(dest) as zf:
             _safe_extractall(zf, target)
     finally: