fix: deliver MAME trees a search setting moves

A tree installed with MAME sits where its search setting points by
default. When a launcher passes the setting, MAME reads the folder it is
given and never the installed copy: RetroBat passes -hash bios/mame/hash
and -sp bios/mame/samples (Mame64.Generator.cs:30, 101, 106-107, 172,
177-178), KNULLI -samplepath /userdata/bios/mame/samples
(mameGenerator.py:129), RetroDECK samplepath $bios_path/mame-sa/samples
(mame/component_prepare.sh:94, 117). A bundled entry whose layout folder a
passed search setting (standalone_pools) binds is now delivered there.

A moved directory entry is found by its layout path and laid out below
the platform's folder, the folder proving nothing about content. A layout
tail two trees answer (MAME's hash/) falls back on the platform's tail. A
file the profile names itself only shadows a tree member of the same build
below the same root.

Manifests: RetroDECK gains the 19 floppy samples in bios/mame-sa/samples/
floppy. RetroBat's hash/ and samples/floppy and KNULLI's samples/floppy
reach the folders the libretro layout already fills, with the same files.

scripts/common.py

@@ -2760,27 +2760,49 @@ def expand_directory_entries(
 
     if not any(entry.get("type") == "directory" for entry in files):
         return files
+    # A file the profile names itself is left to that entry, in the same
+    # build and below the same root: MAME's libretro floppy samples share
+    # their path with the standalone tree RetroPie reads below roms/.
+    other_build = "libretro" if standalone else "standalone"
     named = {
-        destination(entry) for entry in files if entry.get("type") != "directory"
+        (entry.get("root") or "", destination(entry)) for entry in files
+        if entry.get("type") != "directory" and entry.get("mode") != other_build
     }
     expanded: list[dict] = []
     for entry in files:
         if entry.get("type") != "directory":
             expanded.append(entry)
             continue
-        members = directory_members(db, destination(entry))
+        target = destination(entry)
+        # A directory a platform moved (platform_layouts) is the profile's
+        # tree at the platform's place: the collection holds it under the
+        # layout path, and the platform's folder proves nothing (RetroDECK
+        # hands MAME samplepath $bios_path/mame-sa/samples).
+        layout = str(entry.get("layout_path") or "") if standalone else ""
+        members = directory_members(db, layout) if layout else {}
+        if not members:
+            # A layout tail two trees answer (MAME's hash/) leaves the
+            # platform's own tail.
+            layout = ""
+            members = directory_members(db, target)
+        if layout and layout.strip("/") != target.strip("/"):
+            source, place = layout.strip("/") + "/", target.strip("/") + "/"
+            members = {
+                place + dest[len(source):]: sha1
+                for dest, sha1 in members.items() if dest.startswith(source)
+            }
         if not members:
             expanded.append(entry)
             continue
         inherited = {
             key: value
             for key, value in entry.items()
-            if key not in ("type", "standalone_path")
+            if key not in ("type", "standalone_path", "layout_path")
         }
         expanded.extend(
             {**inherited, "name": dest, "path": dest, "sha1": sha1}
             for dest, sha1 in members.items()
-            if dest not in named
+            if (entry.get("root") or "", dest) not in named
         )
     return expanded
 
@@ -3274,6 +3296,20 @@ def platform_layouts(
     def bindings_of(entry: dict) -> dict[str, tuple[str, str]]:
         return bindings_for(launch_systems(entry))
 
+    # The layout folders a search setting stands for (standalone_pools):
+    # bound, the launcher passes the setting and the default is not read.
+    pool_folders = {
+        str(v).strip("/") for v in (profile.get("standalone_pools") or {}).values()
+    } - {""}
+
+    def passed_setting(entry: dict) -> bool:
+        layout = str(standalone_layout_path(entry, profile) or "")
+        bindings = bindings_of(entry)
+        return any(
+            folder in bindings and (layout == folder or layout.startswith(folder + "/"))
+            for folder in pool_folders
+        )
+
     def destinations(entry: dict) -> list[tuple[str, str] | None]:
         """Each place the entry's launches read it from, in launch order.
 
@@ -3316,7 +3352,14 @@ def platform_layouts(
             if not places:
                 files.append({**f, "unplaced": OUTSIDE_BIOS_FOLDER})
                 continue
-            files.extend(_placed_entry(f, profile, placed) for placed in places)
+            moved = f
+            if f.get("bundled") and passed_setting(f):
+                # The copy installed with the emulator sits where the setting
+                # pointed before the launcher moved it: RetroBat passes MAME
+                # -hash bios/mame/hash (Mame64.Generator.cs:172, 177-178), and
+                # the hash/ beside mame.exe is no longer read.
+                moved = {k: v for k, v in f.items() if k != "bundled"}
+            files.extend(_placed_entry(moved, profile, placed) for placed in places)
         standalone = {**profile, "files": files}
     dual = {c.removeprefix(DUAL_MODE_PREFIX) for c in standalone_cores
             if c.startswith(DUAL_MODE_PREFIX)}

tests/test_launcher_placement.py

@@ -851,6 +851,40 @@ class MameSearchPaths(unittest.TestCase):
             e.get("unplaced") == "outside_bios_folder" for e in self.sets(view)
         ))
 
+    def test_a_passed_search_setting_leaves_the_bundled_tree_unread(self) -> None:
+        # RetroBat passes -hash bios/mame/hash and -sp bios/mame/samples
+        # (Mame64.Generator.cs:30, 101, 106-107, 172, 177-178), RetroDECK
+        # writes samplepath $bios_path/mame-sa/samples (component_prepare.sh:94):
+        # the trees beside the executable are not read, the pack brings them.
+        for platform, tree, place in (
+            ("retrobat", "hash/", "mame/hash/"),
+            ("retrobat", "floppy/", "mame/samples/floppy/"),
+            ("knulli", "floppy/", "mame/samples/floppy/"),
+            ("retrodeck", "floppy/", "mame-sa/samples/floppy/"),
+        ):
+            view = standalone_view("mame", platform)
+            (entry,) = [e for e in view["files"]
+                        if e["name"] == tree and e.get("mode") == "standalone"]
+            self.assertEqual(entry["standalone_path"], place, platform)
+            self.assertNotIn("bundled", entry, platform)
+        # Where no launcher passes the setting, the bundled copy is read.
+        view = standalone_view("mame", "emudeck")
+        (entry,) = [e for e in view["files"]
+                    if e["name"] == "hash/" and e.get("mode") == "standalone"]
+        self.assertTrue(entry.get("bundled"))
+
+    def test_a_moved_tree_is_found_by_its_layout_path(self) -> None:
+        from common import expand_directory_entries, load_database
+
+        db = load_database(str(REPO_ROOT / "database.json"))
+        view = standalone_view("mame", "retrodeck")
+        (tree,) = [e for e in view["files"]
+                   if e["name"] == "floppy/" and e.get("mode") == "standalone"]
+        members = expand_directory_entries([tree], db, standalone=True)
+        self.assertEqual(len(members), 19)
+        for member in members:
+            self.assertTrue(member["path"].startswith("mame-sa/samples/floppy/"))
+
     def test_psxmame_reads_bios_psxmame_bios(self) -> None:
         # -rompath bios/psxmame/bios;<rom directory> (PSXMame.Generator.cs:38-48).
         view = standalone_view("psxmame", "retrobat")