fix(ci): keep source-only indexes in GPU test env resolution

.github/actions/setup-gpu-test-env/action.yml

@@ -81,15 +81,31 @@ runs:
         import tomllib
 
         with open(sys.argv[1], "rb") as handle:
-            indexes = tomllib.load(handle)["tool"]["uv"]["index"]
+            uv_config = tomllib.load(handle)["tool"]["uv"]
 
+        indexes = uv_config["index"]
         cuda_extra = sys.argv[2]
+
+        # Some indexes are reached only through [tool.uv.sources] and carry no
+        # CUDA variant in their name or URL (flashinfer-cubin serves a single
+        # https://flashinfer.ai/whl/ for every extra). We pass --no-sources
+        # below, so collect those by their declared extra or they are dropped.
+        source_indexes = {
+            entry["index"]
+            for value in uv_config.get("sources", {}).values()
+            for entry in (value if isinstance(value, list) else [value])
+            if isinstance(entry, dict)
+            and entry.get("extra") == cuda_extra
+            and "index" in entry
+        }
+
         print(
             "\n".join(
                 index["url"]
                 for index in indexes
                 if index["name"].endswith(f"-{cuda_extra}")
                 or f"/{cuda_extra}" in index["url"]
+                or index["name"] in source_indexes
             )
         )
         PY