fix: count a core file filling a declaration

In existence mode the builder packs a core's file at a destination the
platform declares and does not hold, and counts the declaration met.
verify now reads the same placement and reports it OK, so both sides
agree on the platform's count.

scripts/verify.py

@@ -763,15 +763,19 @@ def _mark_hidden(
     shipped: dict[str, str],
     target_cores: set[str] | None,
     region_drops: set[str] | None = None,
-) -> None:
-    """What the builder holds but cannot place beside the files it packed."""
+) -> set[str]:
+    """What the builder holds but cannot place beside the files it packed.
+
+    Returns the full destinations the builder fills with a core's file.
+    """
     from packextras import hidden_extras
 
+    placed: set[str] = set()
     hidden = hidden_extras(
         config, emulators_dir, db,
         emu_profiles if emu_profiles is not None
         else load_emulator_profiles(emulators_dir),
-        shipped, target_cores, region_drops,
+        shipped, target_cores, region_drops, placed,
     )
     for u in undeclared:
         reason = hidden.get(
@@ -780,6 +784,7 @@ def _mark_hidden(
         if reason and u.get("in_repo") and u.get("in_pack", True):
             u["in_pack"] = False
             u["omitted"] = _HIDDEN_REASONS[reason]
+    return placed
 
 
 def _twin_index(
@@ -987,6 +992,7 @@ def verify_platform(
     )
 
     shipped: dict[str, str] = {}
+    results_at: dict[str, list[dict]] = {}
     for sys_id, system in verify_systems.items():
         for file_entry in system.get("files", []):
             if region_drops and (
@@ -1055,6 +1061,7 @@ def verify_platform(
             dest = file_entry.get("destination", file_entry.get("name", ""))
             if not dest:
                 dest = f"{sys_id}/{file_entry.get('name', '')}"
+            results_at.setdefault(dest, []).append(result)
             required = file_entry.get("required", True)
             cur = result["status"]
             prev = file_status.get(dest)
@@ -1069,21 +1076,6 @@ def verify_platform(
             ):
                 file_severity[dest] = sev
 
-    # Count by severity
-    counts = {
-        Severity.OK: 0,
-        Severity.INFO: 0,
-        Severity.WARNING: 0,
-        Severity.CRITICAL: 0,
-    }
-    for s in file_severity.values():
-        counts[s] = counts.get(s, 0) + 1
-
-    # Count by file status (ok/untested/missing)
-    status_counts: dict[str, int] = {}
-    for s in file_status.values():
-        status_counts[s] = status_counts.get(s, 0) + 1
-
     # Cross-reference undeclared files
     if supplemental_names is None:
         from cross_reference import _build_supplemental_index
@@ -1107,10 +1099,36 @@ def verify_platform(
             not in region_drops
         ]
     _mark_unplaced(config, undeclared, profiles)
-    _mark_hidden(
+    placed = _mark_hidden(
         config, undeclared, emulators_dir, db, emu_profiles, shipped, target_cores,
         region_drops,
     )
+    if not reads_file_contents(mode):
+        # An existence frontend is satisfied by any file at the path, and the
+        # builder fills a free platform destination with a core's file.
+        for dest, status in file_status.items():
+            full = f"{base_dest}/{dest}" if base_dest else dest
+            if status == Status.MISSING and full in placed:
+                file_status[dest] = Status.OK
+                file_severity[dest] = Severity.OK
+                for result in results_at.get(dest, []):
+                    result["status"] = Status.OK
+
+    # Count by severity
+    counts = {
+        Severity.OK: 0,
+        Severity.INFO: 0,
+        Severity.WARNING: 0,
+        Severity.CRITICAL: 0,
+    }
+    for s in file_severity.values():
+        counts[s] = counts.get(s, 0) + 1
+
+    # Count by file status (ok/untested/missing)
+    status_counts: dict[str, int] = {}
+    for s in file_status.values():
+        status_counts[s] = status_counts.get(s, 0) + 1
+
     exclusions = find_exclusion_notes(
         config, emulators_dir, emu_profiles, target_cores=target_cores
     )