From 356a101c533fd7a9c56315660b894dd28abd94ac Mon Sep 17 00:00:00 2001
From: Abdessamad Derraz <3028866+Abdess@users.noreply.github.com>
Date: Wed, 28 Oct 2026 00:29:09 +0100
Subject: [PATCH] fix: call a region claim ambiguous on every file

PCSX-ReARMed opens the three regional BIOS files whatever the disc, and the rule called that a confirmation because one of them held the region. A run that opened its own region's file and the others too now settles nothing.
---
 scripts/region_check.py    | 11 ++++++++---
 tests/test_region_check.py |  5 +++++
 wiki/tools.md              |  2 +-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/scripts/region_check.py b/scripts/region_check.py
index fa95d159a..3ba28643b 100644
--- a/scripts/region_check.py
+++ b/scripts/region_check.py
@@ -114,8 +114,9 @@ def outcome(records: dict[str, dict], entries: list[dict], region: str) -> dict:
     """What the four records of one game on one core settle.
 
     `selected` is the regional file the core opened with every one staged.
-    The `region:` claim is `confirmed` when the regions of what it opened
-    hold the game's region, `contradicted` when none does, `unread` when it
+    The `region:` claim is `confirmed` when every regional file it opened
+    holds the game's region, `contradicted` when none does, `ambiguous`
+    when it opened its own region's file and others too, `unread` when it
     opened none. Each variant's result is its oracle verdict. While no
     reference frame is known for the game, a variant that samples the same
     frames as the full run (`as_full`) boots, and one that does not stays
@@ -128,8 +129,12 @@ def outcome(records: dict[str, dict], entries: list[dict], region: str) -> dict:
         claim = "unrun"
     elif not selected:
         claim = "unread"
-    elif any(region in regions_of(by_dest[d]) for d in selected):
+    elif all(region in regions_of(by_dest[d]) for d in selected):
         claim = "confirmed"
+    elif any(region in regions_of(by_dest[d]) for d in selected):
+        # Opened every region's file, to hash them or to choose: the open
+        # alone does not say which one the core runs.
+        claim = "ambiguous"
     else:
         claim = "contradicted"
     results: dict[str, dict] = {}
diff --git a/tests/test_region_check.py b/tests/test_region_check.py
index 806cbaca2..176428fc6 100644
--- a/tests/test_region_check.py
+++ b/tests/test_region_check.py
@@ -135,6 +135,11 @@ class Outcome(unittest.TestCase):
         records = {"full": record("f", self.ALL, ["scph5501.bin"], [[0, "a"]], "boots")}
         self.assertEqual(rc.outcome(records, self.ENTRIES, "japan")["claim"], "contradicted")
 
+    def test_a_core_opening_every_region_file_settles_nothing(self) -> None:
+        """PCSX-ReARMed opens the three regional files whatever the disc."""
+        records = {"full": record("f", self.ALL, self.ALL, [[0, "a"]], "boots")}
+        self.assertEqual(rc.outcome(records, self.ENTRIES, "japan")["claim"], "ambiguous")
+
     def test_region_free_bios(self) -> None:
         records = {"full": record("f", self.ALL, ["scph5501.bin"], [[0, "a"]], "boots"),
                    "own": record("o", ["scph5502.bin"], [], [[0, "a"]], "boots"),
diff --git a/wiki/tools.md b/wiki/tools.md
index 2a8d8231c..06ecfdc76 100644
--- a/wiki/tools.md
+++ b/wiki/tools.md
@@ -1129,7 +1129,7 @@ python scripts/region_check.py report        # the outcome of every region recor
 
 The file the core opened in the `full` run, read from strace, settles the
 claim: `confirmed` when its `region:` holds the game's region, `contradicted`
-when it does not, `unread` when the core opened none of them. Each variant's
+when it does not, `ambiguous` when the core opened its own region's file and the others too (PCSX-ReARMed opens all three), `unread` when it opened none of them. Each variant's
 result is the oracle verdict of its record. While the oracle has no reference
 frame for a game, a variant counts as booting when it samples the same frames
 as the `full` run, and the outcome says it was judged that way. Other frames give no verdict: the US disc reaches its game on the Japanese and European BIOS through another licence screen. The system