fix: install the variant the pack ships

scripts/generate_pack.py

@@ -73,6 +73,8 @@ from nativemode import (
     reads_file_contents,
 )
 from validation import (
+    destination_owners,
+    validated_choice,
     inner_rom_check,
     settle_mismatch,
     agnostic_substitute,
@@ -643,6 +645,7 @@ def generate_pack(
             for name in resolve_platform_cores(config, emu_profiles)
         }
         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
     )
@@ -904,33 +907,15 @@ def generate_pack(
                 # Platform verification (existence/md5) is the authority for pack status.
                 # Emulator checks are supplementary -logged but don't downgrade.
                 # When a discrepancy is found, try to find a file satisfying both.
-                if (
-                    file_status.get(dedup_key) == "ok"
-                    and local_path
-                    and validation_index
-                ):
-                    fname = file_entry.get("name", "")
-                    check = check_file_validation(
-                        local_path, fname, validation_index, bios_dir
+                if file_status.get(dedup_key) == "ok":
+                    local_path, disagreement = validated_choice(
+                        file_entry, local_path, db, validation_index, bios_dir,
+                        digest_algorithm(verification_mode), dest, validation_owners,
                     )
-                    if check:
-                        reason, emus_list = check
-                        better = find_validated_variant(
-                            file_entry,
-                            db,
-                            local_path,
-                            validation_index,
-                            bios_dir,
-                            platform_digest=digest_algorithm(verification_mode),
+                    if disagreement:
+                        file_reasons.setdefault(
+                            dedup_key, f"{platform_display} says OK but {disagreement}"
                         )
-                        if better:
-                            local_path = better
-                        else:
-                            emus = ", ".join(emus_list)
-                            file_reasons.setdefault(
-                                dedup_key,
-                                f"{platform_display} says OK but {emus} says {reason}",
-                            )
 
                 if already_packed:
                     continue
@@ -3039,6 +3024,8 @@ def generate_manifest(
         name: emu_profiles[name]
         for name in _platform_cores(config, emu_profiles)
     }
+    manifest_validation = _build_validation_index(manifest_profiles)
+    manifest_owners = destination_owners(manifest_profiles)
 
     # Load registry for install metadata
     registry: dict = {}
@@ -3179,6 +3166,12 @@ def generate_manifest(
                 ):
                     record_omission(full_dest, file_entry, sys_id, status, None)
                     continue
+                # The variant the pack ships when an emulator rejects the
+                # resolved file: the installer must place the same bytes.
+                local_path, _disagreement = validated_choice(
+                    file_entry, local_path, db, manifest_validation, bios_dir,
+                    digest_algorithm(verification_mode), dest, manifest_owners,
+                )
 
                 # Get SHA1 and size. The installer fetches by hash, so record
                 # the copy this repo holds: an upstream hash carried by no

scripts/validation.py

@@ -490,3 +490,72 @@ def settle_mismatch(
     ):
         return "frontend_digest_exact"
     return status
+
+
+def destination_owners(profiles: dict) -> dict[str, list[tuple[str, str]]]:
+    """For each file name, the path tail each emulator reads it under."""
+    owners: dict[str, list[tuple[str, str]]] = {}
+    for emu_name, profile in profiles.items():
+        for f in profile.get("files", []):
+            name = str(f.get("name") or "")
+            if not name:
+                continue
+            for declared in {f.get("path"), f.get("standalone_path")} - {None, ""} or {name}:
+                owners.setdefault(name.lower(), []).append(
+                    (str(declared).replace("\\", "/").lower(), emu_name)
+                )
+    return owners
+
+
+def _owners_of(destination: str, name: str, owners: dict) -> set[str]:
+    """Emulators whose declared path is the longest tail of the destination."""
+    destination = destination.replace("\\", "/").lower()
+    matching = [
+        (tail, emu) for tail, emu in owners.get(name.lower(), [])
+        if destination == tail or destination.endswith("/" + tail)
+    ]
+    if not matching:
+        return set()
+    longest = max(len(tail) for tail, _emu in matching)
+    return {emu for tail, emu in matching if len(tail) == longest}
+
+
+def validated_choice(
+    file_entry: dict,
+    local_path: str | None,
+    db: dict,
+    validation_index: dict,
+    bios_dir: str,
+    platform_digest: str | None,
+    destination: str = "",
+    owners: dict | None = None,
+) -> tuple[str | None, str | None]:
+    """The file a platform destination ships, and the disagreement if any.
+
+    A frontend's own check can pass while an emulator it runs rejects the
+    file; a held variant both accept replaces it. The pack and the install
+    manifest both read this, so they name the same file. A destination
+    another emulator declares more precisely is that emulator's: ZEsarUX's
+    48 KB cpc6128.rom check has no say over ep128emu/roms/cpc6128.rom.
+    """
+    if not local_path or not validation_index:
+        return local_path, None
+    name = file_entry.get("name", "")
+    rules = validation_index.get(name)
+    if rules and owners and destination:
+        owning = _owners_of(destination, name, owners)
+        if owning and not owning & set(rules["emulators"]):
+            return local_path, None
+    check = check_file_validation(
+        local_path, file_entry.get("name", ""), validation_index, bios_dir
+    )
+    if not check:
+        return local_path, None
+    better = find_validated_variant(
+        file_entry, db, local_path, validation_index, bios_dir,
+        platform_digest=platform_digest,
+    )
+    if better:
+        return better, None
+    reason, emulators = check
+    return local_path, f"{', '.join(emulators)} says {reason}"

tests/test_validated_choice.py

@@ -0,0 +1,104 @@
+"""The pack and the install manifest place the same bytes at a destination.
+
+The builder replaced a file an emulator rejects by a held variant both
+accept; the manifest kept the first resolution. install.py then placed the
+PS2 ROM2.BIN at galaksija/ROM2.BIN where the pack carried the Galaksija ROM,
+across 14 destinations on six platforms.
+"""
+
+from __future__ import annotations
+
+import ast
+import hashlib
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+from validation import (  # noqa: E402
+    _build_validation_index,
+    destination_owners,
+    validated_choice,
+)
+
+
+class ValidatedChoice(unittest.TestCase):
+    def test_a_rejected_file_gives_way_to_an_accepted_variant(self):
+        with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as tmp:
+            wrong = Path(tmp) / "ps2" / "ROM2.BIN"
+            right = Path(tmp) / "galaksija" / "ROM2.BIN"
+            wrong.parent.mkdir()
+            right.parent.mkdir()
+            wrong.write_bytes(b"p" * 64)
+            right.write_bytes(b"g" * 4096)
+            db = {
+                "files": {
+                    hashlib.sha1(p.read_bytes()).hexdigest(): {
+                        "path": str(p),
+                        "name": "ROM2.BIN",
+                        "size": p.stat().st_size,
+                        "md5": hashlib.md5(p.read_bytes()).hexdigest(),
+                    }
+                    for p in (wrong, right)
+                },
+                "indexes": {"by_name": {}, "by_md5": {}},
+            }
+            db["indexes"]["by_name"]["ROM2.BIN"] = list(db["files"])
+            index = _build_validation_index({
+                "galaksija": {
+                    "emulator": "galaksija",
+                    "files": [{"name": "ROM2.BIN", "size": 4096, "validation": ["size"]}],
+                }
+            })
+            chosen, disagreement = validated_choice(
+                {"name": "ROM2.BIN"}, str(wrong), db, index, tmp, None
+            )
+            self.assertEqual(chosen, str(right))
+            self.assertIsNone(disagreement)
+
+    def test_a_destination_another_emulator_owns_is_not_judged(self):
+        """ZEsarUX's 48 KB cpc6128.rom check gave ep128emu the composite image."""
+        profiles = {
+            "zesarux": {"files": [
+                {"name": "cpc6128.rom", "size": 49152, "validation": ["size"]},
+            ]},
+            "ep128emu": {"files": [
+                {"name": "cpc6128.rom", "path": "ep128emu/roms/cpc6128.rom"},
+            ]},
+        }
+        index = _build_validation_index(profiles)
+        owners = destination_owners(profiles)
+        with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as tmp:
+            rom = Path(tmp) / "cpc6128.rom"
+            rom.write_bytes(b"c" * 32768)
+            db = {"files": {}, "indexes": {"by_name": {}, "by_md5": {}}}
+            for destination, judged in (
+                ("ep128emu/roms/cpc6128.rom", False),
+                ("cpc6128.rom", True),
+            ):
+                with self.subTest(destination=destination):
+                    _chosen, disagreement = validated_choice(
+                        {"name": "cpc6128.rom"}, str(rom), db, index, tmp, None,
+                        destination, owners,
+                    )
+                    self.assertEqual(disagreement is not None, judged)
+
+    def test_pack_and_manifest_both_read_it(self):
+        tree = ast.parse((REPO_ROOT / "scripts" / "generate_pack.py").read_text(encoding="utf-8"))
+        callers = {
+            node.name
+            for node in ast.walk(tree)
+            if isinstance(node, ast.FunctionDef)
+            and any(
+                isinstance(call, ast.Call) and getattr(call.func, "id", None) == "validated_choice"
+                for call in ast.walk(node)
+            )
+        }
+        self.assertLessEqual({"generate_pack", "generate_manifest"}, callers)
+
+
+if __name__ == "__main__":
+    unittest.main()