docs: describe short md5 handling as the code does

No platform YAML holds an md5 shorter than 32 characters: the Batocera scraper completes one when a single collection md5 starts with it. The pages said some entries carry 29 characters and that scrapers store them as-is.

tests/test_doc_pages.py

@@ -497,5 +497,31 @@ class EmulatorVerboseSample(unittest.TestCase):
                 self.assertIn(line, printed)
 
 
+class ShortMd5Handling(unittest.TestCase):
+    """Three pages said some Batocera entries carry 29-character MD5s and show
+    as untested. No platform YAML holds one, since the Batocera scraper
+    completes them, and adding-a-scraper.md said to store them as-is."""
+
+    def test_no_page_claims_short_md5_entries(self):
+        offenders = [
+            page.name for page in PUBLISHED
+            if re.search(r"(?i)29[- ]char|truncated md5 hashes in some entries|store the hash as-is",
+                         page.read_text(encoding="utf-8"))
+        ]
+        self.assertEqual(offenders, [])
+
+    def test_the_page_names_what_the_code_does(self):
+        import common
+        from scraper import batocera_scraper
+
+        scraper = inspect.getsource(batocera_scraper)
+        self.assertIn("md5 = _resolve_truncated_md5(", scraper)
+        resolver = inspect.getsource(common.resolve_local_file)
+        self.assertIn("if len(md5_candidate) < 32:", resolver)
+        self.assertIn("_md5_name_ok(path)", resolver)
+        section = _section(_page("verification-modes.md"), "MD5 shorter than 32 characters (Batocera)")
+        self.assertIn("_resolve_truncated_md5", section)
+
+
 if __name__ == "__main__":
     unittest.main()

tests/test_e2e.py

@@ -265,7 +265,7 @@ class TestE2E(unittest.TestCase):
         ).hexdigest()  # sorted: a.rom, b.rom
         multi_wrong = "0000000000000000000000000000000"
         multi_right = f["multi.zip"]["inner_md5s"]["rom.bin"]
-        truncated_md5 = f["truncated.bin"]["md5"][:29]  # Batocera 29-char
+        truncated_md5 = f["truncated.bin"]["md5"][:29]  # shorter than 32 characters
 
         config = {
             "platform": "TestMD5",
@@ -347,7 +347,7 @@ class TestE2E(unittest.TestCase):
                             "zipped_file": "rom.bin",
                             "required": True,
                         },
-                        # Truncated MD5 (Batocera 29 chars)
+                        # MD5 shorter than 32 characters
                         {
                             "name": "truncated.bin",
                             "destination": "truncated.bin",

tests/test_resolution_evidence.py

@@ -86,7 +86,7 @@ class DeclaredHashVerdict(unittest.TestCase):
         )
 
     def test_a_truncated_md5_still_decides(self):
-        """Batocera publishes 29-character prefixes, which are still evidence."""
+        """An MD5 shorter than 32 characters is still evidence, by prefix."""
         self.assertEqual(
             self.verdict(self.right, md5_list=[self.d["md5"][:29]]),
             "data_dir_hash_exact",

tests/test_shipped_content.py

@@ -118,7 +118,7 @@ class ShippedFilesSatisfyTheirDeclaration(unittest.TestCase):
                     digests["md5"].append(common.md5_composite(str(blob_path)))
                 except (zipfile.BadZipFile, OSError):
                     pass
-                # Batocera publishes 29-character prefixes, so compare by prefix.
+                # A declared MD5 can be shorter than 32 characters: compare by prefix.
                 satisfied = any(
                     all(
                         any(