fix: synchronize the engine submodule URL before updating

Reproduce stale upstream configuration with real local Git repositories, including the already-matching pin fast path.

Co-authored-by: Codex <codex@openai.com>

tools/airdef.py

@@ -73,13 +73,12 @@ def engine_identity() -> str:
 def fork():
     """Initialize the exact gitlink; never replace a modified developer checkout."""
     expected = engine_commit()
+    matched = False
     if (FORK / ".git").exists():
         current = subprocess.check_output(["git", "rev-parse", "HEAD"], cwd=FORK, text=True).strip()
-        if current == expected:
-            print(f"horizon/: закреплённый коммит {expected}")
-            return
+        matched = current == expected
         dirty = subprocess.check_output(["git", "status", "--porcelain"], cwd=FORK, text=True).strip()
-        if dirty:
+        if not matched and dirty:
             sys.exit("horizon/: есть изменения при другом закреплённом SHA; сохраните их перед обновлением сабмодуля")
         if (FORK / ".git").is_dir():
             # Migrate the old standalone clone without deleting it or any local branches.
@@ -88,6 +87,12 @@ def fork():
             run(["git", "remote", "set-url", "origin", url], cwd=FORK)
     elif FORK.exists() and any(FORK.iterdir()):
         sys.exit("horizon/: непустой каталог без Git; сохраните его перед инициализацией сабмодуля")
+    # Existing clones cache the previous upstream URL in local Git configuration.
+    # Synchronize even when HEAD already matches: the next pin may exist only in our fork.
+    run(["git", "submodule", "sync", "--recursive", "--", "horizon"], cwd=ROOT)
+    if matched:
+        print(f"horizon/: закреплённый коммит {expected}")
+        return
     run(["git", "submodule", "update", "--init", "--recursive", "--", "horizon"], cwd=ROOT)
     current = subprocess.check_output(["git", "rev-parse", "HEAD"], cwd=FORK, text=True).strip()
     if current != expected:

tools/test_airdef_build.py

@@ -0,0 +1,63 @@
+"""Real Git migration regression; no network, user settings or player data."""
+import importlib.util
+import os
+from pathlib import Path
+import subprocess
+import tempfile
+import unittest
+from unittest.mock import patch
+
+SPEC = importlib.util.spec_from_file_location("airdef_build", Path(__file__).with_name("airdef.py"))
+airdef = importlib.util.module_from_spec(SPEC)
+SPEC.loader.exec_module(airdef)
+
+
+def git(at, *args):
+    return subprocess.check_output(["git", "-C", str(at), *args], text=True, stderr=subprocess.STDOUT).strip()
+
+
+def init(at):
+    at.mkdir()
+    git(at, "init", "-q")
+    git(at, "config", "user.name", "Test")
+    git(at, "config", "user.email", "test@example.invalid")
+
+
+def commit(at, text):
+    (at / "engine.txt").write_text(text)
+    git(at, "add", "engine.txt")
+    git(at, "commit", "-qm", text)
+    return git(at, "rev-parse", "HEAD")
+
+
+class ForkMigrationTests(unittest.TestCase):
+    def test_stale_local_url_is_synced_before_fetching_new_pin(self):
+        with tempfile.TemporaryDirectory(prefix="airdef-fork-test-") as tmp, patch.dict(os.environ, {"GIT_ALLOW_PROTOCOL": "file"}):
+            root = Path(tmp)
+            source, parent = root / "source", root / "airdef"
+            init(source)
+            old = commit(source, "old")
+            canonical = root / "canonical.git"
+            git(root, "clone", "--bare", str(source), str(canonical))
+            init(parent)
+            git(parent, "submodule", "add", str(canonical), "horizon")
+            child = parent / "horizon"
+            new = commit(source, "new-fork-only-pin")
+            git(source, "push", str(canonical), "HEAD")
+            git(parent, "update-index", "--cacheinfo", f"160000,{new},horizon")
+            stale = str(root / "missing-upstream.git")
+            git(parent, "config", "submodule.horizon.url", stale)
+            git(child, "remote", "set-url", "origin", stale)
+            self.assertEqual(git(child, "rev-parse", "HEAD"), old)
+            with patch.object(airdef, "ROOT", parent), patch.object(airdef, "FORK", child):
+                airdef.fork()
+                self.assertEqual(git(child, "rev-parse", "HEAD"), new)
+                self.assertEqual(git(child, "remote", "get-url", "origin"), str(canonical))
+                # The fast path must also repair stale configuration for the next update.
+                git(child, "remote", "set-url", "origin", stale)
+                airdef.fork()
+                self.assertEqual(git(child, "remote", "get-url", "origin"), str(canonical))
+
+
+if __name__ == "__main__":
+    unittest.main()