app: ZIMAGE_ONLY switch (no behaviour change here)

app.py

@@ -69,6 +69,10 @@ MODELS = {
         "size_gb": 10.46,
     },
 }
+# ZIMAGE_ONLY=turbo|base pins a Space to one model (the dedicated Turbo Space)
+ONLY = os.environ.get("ZIMAGE_ONLY", "").strip().lower()
+if ONLY in ("turbo", "base"):
+    MODELS = {k: v for k, v in MODELS.items() if v["key"] == ONLY}
 MODEL_NAMES = list(MODELS)
 
 SAMPLE_PROMPTS = [
@@ -288,7 +292,12 @@ def download_bytes(name):
 
 def load_samples():
     items = []
-    for label, repo in (("Z-Image-Turbo", "infosave/Z-Image-Turbo-cmf"), ("Z-Image", "infosave/Z-Image-cmf")):
+    pairs = (("Z-Image-Turbo", "infosave/Z-Image-Turbo-cmf"), ("Z-Image", "infosave/Z-Image-cmf"))
+    if ONLY == "turbo":
+        pairs = pairs[:1]
+    elif ONLY == "base":
+        pairs = pairs[1:]
+    for label, repo in pairs:
         for i, prompt in enumerate(SAMPLE_PROMPTS, 1):
             cap = f"{label}: {prompt} (1024², seed 7)"
             try:
@@ -537,10 +546,13 @@ def build():
     samples = load_samples()
     default_model = MODEL_NAMES[0]
     default_size = "256" if DEVICE == "cpu" else "512"
+    title = "Z-Image-Turbo · CMF" if ONLY == "turbo" else ("Z-Image · CMF")
     header = (
-        "# Z-Image · CMF\n"
-        "Text-to-image with Tongyi-MAI's Z-Image and Z-Image-Turbo (6B DiT + Qwen3-4B text encoder), "
-        f"run by [cortiq]({GITHUB}), a Rust engine with no Python ML stack. "
+        f"# {title}\n"
+        + ("Text-to-image with Tongyi-MAI's Z-Image-Turbo (6B DiT + Qwen3-4B text encoder, 8 steps, no CFG), "
+           if ONLY == "turbo" else
+           "Text-to-image with Tongyi-MAI's Z-Image and Z-Image-Turbo (6B DiT + Qwen3-4B text encoder), ")
+        + f"run by [cortiq]({GITHUB}), a Rust engine with no Python ML stack. "
         "Models: [Z-Image-Turbo-cmf](https://huggingface.co/infosave/Z-Image-Turbo-cmf) · "
         "[Z-Image-cmf](https://huggingface.co/infosave/Z-Image-cmf).\n\n"
         f"This Space runs on **{DEVICE_LABEL}**"
@@ -555,7 +567,7 @@ def build():
             else "Jobs run one at a time in a queue."
         )
     )
-    with gr.Blocks(title="Z-Image CMF") as demo:
+    with gr.Blocks(title=title) as demo:
         gr.Markdown(header, elem_id="title")
         with gr.Tabs():
             with gr.Tab("Generate"):