fix: place slot claims where the pack puts extras

scripts/common.py

@@ -1733,7 +1733,7 @@ def platform_declarations(
     declaring a file under a different name than the emulator profile
     (e.g. Batocera ROM1 vs gsplus ROM).
     """
-    prefix = "" if config.get("base_destination") else declared_root(config).lower()
+    prefix = declared_root(config).lower()
     declared: dict[str, list[tuple[int | None, str]]] = {}
     by_md5 = db.get("indexes", {}).get("by_md5", {})
     files_db = db.get("files", {})
@@ -1767,11 +1767,15 @@ def platform_declarations(
 
 
 def declared_root(config: dict) -> str:
-    """The directory nearly every declared destination starts with, if any.
+    """The BIOS directory a platform writes into every destination, if any.
 
-    A platform without base_destination writes it into each destination;
-    core files go under the same directory.
+    Only a platform whose base_destination is explicitly empty does that
+    (RetroDECK writes bios/ in front of each file), and core files go under
+    the same directory. A config that does not state a base says nothing,
+    and its common folder is a system's, not the BIOS root.
     """
+    if config.get("base_destination", None) != "":
+        return ""
     roots = [
         d.split("/", 1)[0]
         for system in config.get("systems", {}).values()

scripts/packextras.py

@@ -436,6 +436,45 @@ def _archive_prefix_extras(
     return extras
 
 
+class ExtraPlacement:
+    """Where a pack puts a core's file, decided once for every reader.
+
+    The builder, and slots.py judging what a destination holds, both read
+    this: placed apart, slot arbitration compared RetroDECK's bios/ claims
+    with core claims at the root and never saw them meet.
+    """
+
+    def __init__(self, config: dict, base_dest: str, profiles: dict) -> None:
+        from common import _norm_system_id
+
+        self.prefix = _detect_extras_prefix(config, base_dest)
+        self.slug_based, self.sys_to_slug = _detect_slug_structure(config)
+        self.platform_systems = set(config.get("systems", {}).keys())
+        self.norm_map = (
+            {_norm_system_id(sid): sid for sid in self.platform_systems}
+            if self.slug_based
+            else {}
+        )
+        self.profiles = profiles
+
+    def place(self, entry: dict, dest: str) -> tuple[str, str] | None:
+        """(pack-relative destination, full destination), or None.
+
+        ``entry`` names its profile and may name its own system. A
+        slug-based platform cannot place a file of a system it has no
+        folder for.
+        """
+        if self.slug_based:
+            slug = _slug_for(
+                entry, self.profiles, self.platform_systems, self.norm_map,
+                self.sys_to_slug,
+            )
+            if not slug:
+                return None
+            dest = f"{slug}/{dest}"
+        return dest, (f"{self.prefix}/{dest}" if self.prefix else dest)
+
+
 def _collect_emulator_extras(
     config: dict,
     emulators_dir: str,
@@ -469,7 +508,7 @@ def _collect_emulator_extras(
 
     Works for ANY platform (RetroArch, Batocera, Recalbox, etc.)
     """
-    from common import _norm_system_id, resolve_platform_cores
+    from common import resolve_platform_cores
     from verify import find_undeclared_files
 
     profiles = (
@@ -479,13 +518,9 @@ def _collect_emulator_extras(
     )
 
     # Detect destination conventions for core extras
-    extras_prefix = _detect_extras_prefix(config, base_dest)
-    is_slug_based, sys_to_slug = _detect_slug_structure(config)
-    platform_systems = set(config.get("systems", {}).keys())
-    norm_map: dict[str, str] = {}
-    if is_slug_based:
-        for sid in platform_systems:
-            norm_map[_norm_system_id(sid)] = sid
+    placement = ExtraPlacement(config, base_dest, profiles)
+    extras_prefix = placement.prefix
+    is_slug_based = placement.slug_based
 
     # Use strict YAML names (no DB alias enrichment) so that files known
     # under an alias still get packed at the emulator's expected path.
@@ -508,15 +543,12 @@ def _collect_emulator_extras(
         dest = f"{raw_dest}{u['name']}" if raw_dest.endswith("/") else raw_dest
 
         # Slug-based platforms: prefix dest with system slug
-        if is_slug_based:
-            slug = _slug_for(u, profiles, platform_systems, norm_map, sys_to_slug)
-            if not slug:
-                if unplaceable is not None:
-                    unplaceable.append(u)
-                continue
-            dest = f"{slug}/{dest}"
-
-        full_dest = f"{extras_prefix}/{dest}" if extras_prefix else dest
+        placed = placement.place(u, dest)
+        if placed is None:
+            if unplaceable is not None:
+                unplaceable.append(u)
+            continue
+        dest, full_dest = placed
         if claimants is not None:
             claimants[(u.get("emulator", ""), u.get("name", ""), u.get("path") or "")] = (
                 sanitize_pack_path(dest)

scripts/slots.py

@@ -136,9 +136,14 @@ def profile_claims(
     standalone_cores: set[str] | None = None,
     zip_contents: dict | None = None,
     data_dir_registry: dict | None = None,
+    config: dict | None = None,
 ) -> list[Claim]:
     """What each emulator profile says belongs at each destination it names.
 
+    With the platform's config, a claim sits where the pack puts the core's
+    file (ExtraPlacement): under RetroDECK's bios/, under RomM's system
+    folder. A file the platform cannot place claims nothing.
+
     A file can exist in one build of an emulator and not the other, and the
     two builds read from different directories. The mode is decided per
     emulator, not per pack: a platform runs some of its emulators as libretro
@@ -148,6 +153,11 @@ def profile_claims(
     ``standalone_path``. This is the gate verify already applies.
     """
     standalone_cores = standalone_cores or set()
+    placement = None
+    if config is not None:
+        from packextras import ExtraPlacement  # noqa: PLC0415
+
+        placement = ExtraPlacement(config, base_dest, profiles)
     claims: list[Claim] = []
     for emu_name, profile in sorted(profiles.items()):
         if profile.get("type") in ("launcher", "alias"):
@@ -174,7 +184,15 @@ def profile_claims(
             ) or entry.get("name") or ""
             if not dest:
                 continue
-            full = f"{base_dest}/{dest}" if base_dest else dest
+            if placement is None:
+                full = f"{base_dest}/{dest}" if base_dest else dest
+            else:
+                placed = placement.place(
+                    {"profile": emu_name, "system": entry.get("system")}, dest
+                )
+                if placed is None:
+                    continue
+                full = placed[1]
             # The owner's own copy is the one the builder ships.
             local, status = resolve_local_file(
                 {**entry, "source_profile": emu_name},
@@ -236,7 +254,8 @@ def find_conflicts(
     # claim at all matches what ships is a disagreement.
     by_slot: dict[str, list[Claim]] = {}
     for claim in profile_claims(
-        profiles, db, base_dest, standalone_cores, zip_contents, data_dir_registry
+        profiles, db, base_dest, standalone_cores, zip_contents, data_dir_registry,
+        config=config,
     ):
         key = _normalize(claim.destination)
         platform = by_dest.get(key)