fix(multiplayer): reconcile authoritative initial connections

server/migrations/0010_initial_connect_ready_at.sql

@@ -0,0 +1,13 @@
+ALTER TABLE matches
+    ADD COLUMN initial_connect_ready_at TIMESTAMPTZ;
+
+-- Existing in-flight matches receive a fresh, fair connection window when
+-- this migration is deployed. Future rows are stamped by the transition to
+-- ASSIGNMENT_READY, not by match creation or provider allocation.
+UPDATE matches
+SET initial_connect_ready_at = now()
+WHERE state IN ('ASSIGNMENT_READY', 'ASSIGNED', 'CONNECTING');
+
+ALTER TABLE matches
+    ADD CONSTRAINT matches_initial_connect_ready_at
+    CHECK (state NOT IN ('ASSIGNMENT_READY', 'ASSIGNED', 'CONNECTING') OR initial_connect_ready_at IS NOT NULL) NOT VALID;

server/migrations/down/0010_initial_connect_ready_at.sql

@@ -0,0 +1,3 @@
+ALTER TABLE matches
+    DROP CONSTRAINT IF EXISTS matches_initial_connect_ready_at,
+    DROP COLUMN IF EXISTS initial_connect_ready_at;

server/migrations/test_migration.py

@@ -9,6 +9,7 @@ ASSIGNMENTS_SQL = (Path(__file__).parent / "0002_assignments.sql").read_text()
 QUOTAS_SQL = (Path(__file__).parent / "0007_allocation_quotas.sql").read_text()
 ARENAS_SQL = (Path(__file__).parent / "0008_match_arena_paths.sql").read_text()
 ALLOCATION_ARENAS_SQL = (Path(__file__).parent / "0009_allocation_arena_paths.sql").read_text()
+INITIAL_CONNECT_READY_SQL = (Path(__file__).parent / "0010_initial_connect_ready_at.sql").read_text()
 
 
 class MigrationTest(unittest.TestCase):
@@ -73,6 +74,10 @@ class MigrationTest(unittest.TestCase):
         self.assertIn("ALTER TABLE allocations", ALLOCATION_ARENAS_SQL)
         self.assertIn("ADD COLUMN arena_path TEXT", ALLOCATION_ARENAS_SQL)
 
+    def test_initial_connect_window_starts_at_assignment_readiness(self):
+        self.assertIn("ADD COLUMN initial_connect_ready_at TIMESTAMPTZ", INITIAL_CONNECT_READY_SQL)
+        self.assertIn("state IN ('ASSIGNMENT_READY', 'ASSIGNED', 'CONNECTING')", INITIAL_CONNECT_READY_SQL)
+
 
 if __name__ == "__main__":
     unittest.main()