fix(core.utils): unpack extra_sources tuples in cache key

extra_sources is a sequence of (name, source) tuples but the prior
fix hashed each item as a flat str/bytes, never reaching the actual
source content. Now unpacks both name and source from each tuple.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: cpcloud

cuda_core/cuda/core/utils/_program_cache.py

@@ -277,11 +277,20 @@ def _update(label: str, payload: bytes) -> None:
     extra_sources = getattr(options, "extra_sources", None)
     if extra_sources:
         _update("extra_sources_count", str(len(extra_sources)).encode("ascii"))
-        for src in extra_sources:
-            if isinstance(src, str):
-                _update("extra_source", src.encode("utf-8"))
-            elif isinstance(src, (bytes, bytearray)):
-                _update("extra_source", bytes(src))
+        for item in extra_sources:
+            # extra_sources is a sequence of (name, source) tuples.
+            if isinstance(item, (tuple, list)) and len(item) == 2:
+                name, src = item
+                _update("extra_source_name", str(name).encode("utf-8"))
+                if isinstance(src, str):
+                    _update("extra_source_code", src.encode("utf-8"))
+                elif isinstance(src, (bytes, bytearray)):
+                    _update("extra_source_code", bytes(src))
+                else:
+                    _update("extra_source_code", str(src).encode("utf-8"))
+            else:
+                # Fallback for unexpected format.
+                _update("extra_source", str(item).encode("utf-8"))
     use_libdevice = getattr(options, "use_libdevice", None)
     if use_libdevice is not None:
         _update("use_libdevice", str(use_libdevice).encode("ascii"))