Add application file update

README.md

@@ -45,6 +45,10 @@ What changed for the reader: sample cards are tapped rather than dragged (Gradio
 - A missing capability is never reported as tampering.
 - Weights are never re-served — the page has no file output component.
 
+## Hardware
+
+The Space runs on the free **ZeroGPU** tier (CPU basic is not selectable for it). ZeroGPU refuses any app without a `@spaces.GPU` function, so `app.py` declares a no-op one that nothing calls; all verification runs on CPU and uses no GPU quota. `requirements.txt` lists `spaces` so the import resolves; locally the import is guarded.
+
 ## Configuration
 
 | env | default | meaning |

app.py

@@ -35,6 +35,23 @@ from pathlib import Path
 
 import gradio as gr
 
+# ZeroGPU runtime (RealFalconsAI/verifier runs on the free ZeroGPU tier — the
+# CPU tier is not selectable for this Space): the runtime kills any app that
+# declares no @spaces.GPU function at startup ("No @spaces.GPU function
+# detected"). The verifier needs no GPU, so the declared function is a no-op
+# that no control ever calls — every verification runs on the CPU path below
+# and consumes no GPU quota. Guarded so `python app.py` runs anywhere.
+try:
+    import spaces as _spaces
+except Exception:  # not on Spaces, or the package is absent
+    _spaces = None
+
+if _spaces is not None:
+    @_spaces.GPU(duration=1)
+    def _zerogpu_placeholder():
+        """Declared for the ZeroGPU runtime only. Never invoked."""
+        return None
+
 from engine_wrapper import (
     BUILD_STAMP, LOCAL_CMD, MANIFEST, MAX_UPLOAD_BYTES, MAX_UPLOAD_MB,
     MAX_REPO_MB, NORMALIZED_NOTE, NOT_A_PACKAGE_COPY, ROOT, SAMPLES_DIR,

engine_wrapper.py

@@ -56,7 +56,7 @@ NOT_A_PACKAGE_COPY = (
 ATTESTATION_PATTERNS = ("lineage.intoto.jsonl",)
 
 # Bumped on every delivered build so a running instance is identifiable.
-BUILD_STAMP = "2026-09-03.4-gradio"
+BUILD_STAMP = "2026-09-03.5-gradio"
 
 # ---------------------------------------------------------------- helpers
 

requirements.txt

@@ -1,3 +1,4 @@
 gradio>=4.44,<6
+spaces
 cryptography
 huggingface_hub