diff --git a/scripts/export_native.py b/scripts/export_native.py
index b54c91a0..a3eb0741 100644
--- a/scripts/export_native.py
+++ b/scripts/export_native.py
@@ -15,6 +15,7 @@ Usage:
 from __future__ import annotations
 
 import argparse
+import json
 import sys
 import urllib.error
 import urllib.request
@@ -31,9 +32,28 @@ _USER_AGENT = "retrobios-exporter/1.0"
 _MAX_BYTES = 64 * 1024 * 1024
 
 
-def fetch(url: str, destination: Path) -> bytes:
-    """Download an original once, then read it from the cache."""
-    if destination.exists():
+def _load_sources(index: Path | None) -> dict[str, str]:
+    if index is None or not index.is_file():
+        return {}
+    try:
+        return json.loads(index.read_text(encoding="utf-8"))
+    except (OSError, json.JSONDecodeError):
+        return {}
+
+
+def fetch(url: str, destination: Path, index: Path | None = None) -> bytes:
+    """Download an original once, then read it from the cache.
+
+    The cache path carries the file's own name and nothing of the revision it
+    came from, so a file fetched under one pin was served under every later
+    one and pinned_base() stopped having any effect after the first run. The
+    URL that produced each cached file is recorded beside the cache, and a
+    different URL refetches. A cache written before this index existed keeps
+    being served: nothing recorded means nothing contradicted.
+    """
+    recorded = _load_sources(index)
+    key = str(destination)
+    if destination.exists() and recorded.get(key, url) == url:
         return destination.read_bytes()
     request = urllib.request.Request(url, headers={"User-Agent": _USER_AGENT})
     with urllib.request.urlopen(request, timeout=60) as response:
@@ -42,6 +62,12 @@ def fetch(url: str, destination: Path) -> bytes:
         raise ValueError(f"{url}: response larger than {_MAX_BYTES} bytes")
     destination.parent.mkdir(parents=True, exist_ok=True)
     destination.write_bytes(payload)
+    if index is not None:
+        recorded[key] = url
+        index.parent.mkdir(parents=True, exist_ok=True)
+        index.write_text(
+            json.dumps(recorded, indent=2, sort_keys=True) + "\n", encoding="utf-8"
+        )
     return payload
 
 
@@ -98,7 +124,7 @@ def collect_originals(
             payload = path.read_bytes()
         elif allow_fetch:
             try:
-                payload = fetch(url, path)
+                payload = fetch(url, path, upstream_dir / ".sources.json")
             except (urllib.error.URLError, urllib.error.HTTPError, OSError) as exc:
                 missing.append(f"{relative}: {exc}")
                 continue
diff --git a/scripts/exporter/emudeck_exporter.py b/scripts/exporter/emudeck_exporter.py
index 1d60a816..df400a0e 100644
--- a/scripts/exporter/emudeck_exporter.py
+++ b/scripts/exporter/emudeck_exporter.py
@@ -113,6 +113,7 @@ class Exporter(BaseExporter):
                 "the checks are code, not data"
             )
 
+        self._withdrawn: dict[str, set[str]] = {}
         pieces: list[str] = []
         cursor = 0
         for name, start, end in self._function_spans(script):
@@ -124,7 +125,15 @@ class Exporter(BaseExporter):
             if md5s and match:
                 # An array compared by membership says nothing about order,
                 # so the same set is left as the maintainer wrote it.
-                if set(md5s) != set(match.group(1).split()):
+                theirs = set(match.group(1).split())
+                # The array was replaced wholesale, so any value EmuDeck holds
+                # and our model does not was deleted: a user whose dump matched
+                # it would stop passing the check. A rewrite that withdraws one
+                # is refused and reported instead.
+                withdrawn = theirs - set(md5s)
+                if withdrawn:
+                    self._withdrawn.setdefault(name, set()).update(withdrawn)
+                elif set(md5s) != theirs:
                     body = (
                         body[: match.start(1)]
                         + " ".join(md5s)
diff --git a/scripts/exporter/retrodeck_exporter.py b/scripts/exporter/retrodeck_exporter.py
index d0e9b9c1..61bb03a1 100644
--- a/scripts/exporter/retrodeck_exporter.py
+++ b/scripts/exporter/retrodeck_exporter.py
@@ -106,6 +106,42 @@ class Exporter(BaseExporter):
                 return nested, "bios"
         return None
 
+    @staticmethod
+    def _merge(existing: object, ours: list[OrderedDict]) -> list[OrderedDict]:
+        """Correct the component's own list; never replace it.
+
+        Assigning our entries wholesale dropped every file RetroDECK declares
+        that our model does not carry -- 177 of them across the components.
+        An entry the platform declares is kept, its fields corrected where the
+        truth has something to say and left alone where it does not, and what
+        the platform does not declare is appended.
+        """
+        by_name: OrderedDict[str, OrderedDict] = OrderedDict()
+        for entry in ours:
+            name = str(entry.get("filename", ""))
+            if name and name not in by_name:
+                by_name[name] = entry
+
+        merged: list[OrderedDict] = []
+        corrected: set[str] = set()
+        for entry in existing if isinstance(existing, list) else []:
+            if not isinstance(entry, dict):
+                continue
+            name = str(entry.get("filename", ""))
+            ours_entry = by_name.get(name)
+            if ours_entry is None:
+                merged.append(OrderedDict(entry))
+                continue
+            combined = OrderedDict(entry)
+            combined.update(ours_entry)
+            merged.append(combined)
+            corrected.add(name)
+
+        merged.extend(
+            entry for name, entry in by_name.items() if name not in corrected
+        )
+        return merged
+
     def render(
         self,
         systems: dict[str, NativeSystem],
@@ -132,10 +168,10 @@ class Exporter(BaseExporter):
                     continue
                 holder = self._bios_holder(component_value)
                 if holder is None:
-                    component_value["bios"] = entries
+                    component_value["bios"] = self._merge(None, entries)
                 else:
                     container, key = holder
-                    container[key] = entries
+                    container[key] = self._merge(container.get(key), entries)
                 break
 
             produced[path] = json.dumps(manifest, indent=2, ensure_ascii=False) + "\n"
diff --git a/tests/test_exporters.py b/tests/test_exporters.py
index e31f9e49..92de7cd6 100644
--- a/tests/test_exporters.py
+++ b/tests/test_exporters.py
@@ -624,6 +624,47 @@ class UpstreamFidelity(unittest.TestCase):
         self.assertEqual(exporter.validate(systems, produced), [])
         return produced, originals
 
+    def test_retrodeck_keeps_every_bios_entry_it_declares(self):
+        """The component list is corrected in place, never replaced.
+
+        Assigning our entries wholesale dropped 114 distinct filenames that
+        RetroDECK's own manifests declare.
+        """
+        produced, originals = self._export("retrodeck")
+
+        def names(text: str) -> set[str]:
+            manifest = json.loads(text)
+            for value in manifest.values():
+                if not isinstance(value, dict):
+                    continue
+                listing = value.get("bios")
+                if listing is None:
+                    for key in ("preset_actions", "cores"):
+                        nested = value.get(key)
+                        if isinstance(nested, dict) and "bios" in nested:
+                            listing = nested["bios"]
+                            break
+                if listing is None:
+                    continue
+                return {
+                    str(e.get("filename", ""))
+                    for e in listing
+                    if isinstance(e, dict)
+                }
+            return set()
+
+        lost: set[str] = set()
+        compared = 0
+        for path, text in produced.items():
+            if path not in originals:
+                continue
+            compared += 1
+            lost |= names(originals[path]) - names(text)
+        self.assertGreater(compared, 0, "no component manifest was compared")
+        self.assertEqual(
+            lost, set(), "the export dropped entries RetroDECK declares"
+        )
+
     def test_recalbox_keeps_every_system_and_every_path(self):
         produced, originals = self._export("recalbox")
         before = parse_untrusted_xml(originals["es_bios.xml"], "es_bios.xml")
@@ -745,6 +786,26 @@ class UpstreamFidelity(unittest.TestCase):
             )
         self.assertEqual(result.returncode, 0, result.stderr)
 
+    def test_emudeck_keeps_every_md5_it_declares(self):
+        """An md5 the platform holds is never withdrawn from its array.
+
+        The array was assigned wholesale, so any value our model did not
+        carry disappeared and a user whose dump matched it stopped passing
+        EmuDeck's own check.
+        """
+        produced, originals = self._export("emudeck")
+        pattern = re.compile(r"local\s+hashes=\(([^)]*)\)")
+        before = pattern.findall(originals["checkBIOS.sh"])
+        after = pattern.findall(produced["checkBIOS.sh"])
+        self.assertEqual(len(before), len(after), "an md5 array vanished")
+        for index, (was, now) in enumerate(zip(before, after)):
+            with self.subTest(array=index):
+                self.assertEqual(
+                    set(was.split()) - set(now.split()),
+                    set(),
+                    "the export withdrew an md5 EmuDeck declares",
+                )
+
     def test_retrobat_keeps_every_system_and_every_file(self):
         produced, originals = self._export("retrobat")
         before = json.loads(originals["batocera-systems.json"])