fix: arbitrate slots for the target and source

scripts/generate_pack.py

@@ -610,7 +610,8 @@ def generate_pack(
         validation_index = _build_validation_index(platform_profiles)
     validation_owners = destination_owners(platform_profiles)
     slot_overrides = slots.pack_overrides(
-        config, emu_profiles or {}, db, zip_contents, data_registry
+        config, emu_profiles or {}, db, zip_contents, data_registry,
+        target_cores=target_cores, source=source,
     )
 
     # Filter systems by target if specified
@@ -3437,7 +3438,8 @@ def generate_manifest(
     if data_registry is None:
         data_registry = load_data_dir_registry(platforms_dir)
     slot_overrides = slots.pack_overrides(
-        config, emu_profiles, db, zip_contents, data_registry
+        config, emu_profiles, db, zip_contents, data_registry,
+        target_cores=target_cores, source=source,
     )
 
     def manifest_destination(full_destination: str) -> str:

scripts/slots.py

@@ -416,6 +416,8 @@ def pack_overrides(
     db: dict,
     zip_contents: dict | None = None,
     data_dir_registry: dict | None = None,
+    target_cores: set[str] | None = None,
+    source: str = "full",
 ) -> dict[str, str]:
     """Full pack destination -> the file a platform pack serves there instead.
 
@@ -428,10 +430,14 @@ def pack_overrides(
     """
     from common import resolve_platform_cores
 
-    if not profiles:
+    # A baseline-only pack serves what the platform declares, and a target's
+    # pack answers to the cores that hardware builds: DuckStation does not
+    # exist on any RetroArch target and still replaced its scph5000.bin.
+    if not profiles or source == "platform":
         return {}
     platform_profiles = {
-        name: profiles[name] for name in resolve_platform_cores(config, profiles)
+        name: profiles[name]
+        for name in resolve_platform_cores(config, profiles, target_cores=target_cores)
     }
     mode = config.get("verification_mode", "existence")
     overrides: dict[str, str] = {}

scripts/verify.py

@@ -912,7 +912,8 @@ def verify_platform(
     slot_overrides = {
         (key[len(base_dest) + 1:] if base_dest and key.startswith(f"{base_dest}/") else key): path
         for key, path in slots.pack_overrides(
-            config, emu_profiles or {}, db, zip_contents, data_dir_registry
+            config, emu_profiles or {}, db, zip_contents, data_dir_registry,
+            target_cores=target_cores,
         ).items()
     }