fix: make code index migration mysql-compatible

app/main.py

@@ -96,6 +96,25 @@ def _migrate_schema():
             {"column_name": column_name},
         ).fetchone() is not None
 
+    def _has_index(db, table_name: str, index_name: str) -> bool:
+        return db.execute(
+            text(
+                """
+                SELECT 1
+                FROM information_schema.STATISTICS
+                WHERE TABLE_SCHEMA = DATABASE()
+                  AND TABLE_NAME = :table_name
+                  AND INDEX_NAME = :index_name
+                LIMIT 1
+                """
+            ),
+            {"table_name": table_name, "index_name": index_name},
+        ).fetchone() is not None
+
+    def _ensure_unique_index(db, table_name: str, index_name: str, columns_sql: str):
+        if not _has_index(db, table_name, index_name):
+            db.execute(text(f"CREATE UNIQUE INDEX {index_name} ON {table_name} ({columns_sql})"))
+
     def _drop_fk_constraints(db, table_name: str, referenced_table: str):
         rows = db.execute(text(
             """
@@ -139,9 +158,7 @@ def _migrate_schema():
         result = db.execute(text("SHOW COLUMNS FROM projects LIKE 'project_code'"))
         if not result.fetchone():
             db.execute(text("ALTER TABLE projects ADD COLUMN project_code VARCHAR(16) NULL"))
-            db.execute(text("CREATE UNIQUE INDEX idx_projects_project_code ON projects (project_code)"))
+        _ensure_unique_index(db, "projects", "idx_projects_project_code", "project_code")
-        else:
-            db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_projects_project_code ON projects (project_code)"))
 
         # projects.owner_name
         result = db.execute(text("SHOW COLUMNS FROM projects LIKE 'owner_name'"))
@@ -176,7 +193,7 @@ def _migrate_schema():
             db.execute(text("ALTER TABLE tasks ADD COLUMN created_by_id INTEGER NULL"))
             _ensure_fk(db, "tasks", "created_by_id", "users", "id", "fk_tasks_created_by_id")
         if _has_column(db, "tasks", "task_code"):
-            db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_tasks_task_code ON tasks (task_code)"))
+            _ensure_unique_index(db, "tasks", "idx_tasks_task_code", "task_code")
 
         # milestones creator field
         result = db.execute(text("SHOW COLUMNS FROM milestones LIKE 'created_by_id'"))
@@ -207,7 +224,7 @@ def _migrate_schema():
         # --- Milestone status enum migration (old -> new) ---
         if _has_table(db, "milestones"):
             if _has_column(db, "milestones", "milestone_code"):
-                db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_milestones_milestone_code ON milestones (milestone_code)"))
+                _ensure_unique_index(db, "milestones", "idx_milestones_milestone_code", "milestone_code")
             # Alter enum column to accept new values
             db.execute(text(
                 "ALTER TABLE milestones MODIFY COLUMN status "
@@ -264,16 +281,16 @@ def _migrate_schema():
             db.execute(text("ALTER TABLE server_states ADD COLUMN plugin_version VARCHAR(64) NULL"))
 
         if _has_table(db, "meetings") and _has_column(db, "meetings", "meeting_code"):
-            db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_meetings_meeting_code ON meetings (meeting_code)"))
+            _ensure_unique_index(db, "meetings", "idx_meetings_meeting_code", "meeting_code")
 
         if _has_table(db, "supports") and _has_column(db, "supports", "support_code"):
-            db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_supports_support_code ON supports (support_code)"))
+            _ensure_unique_index(db, "supports", "idx_supports_support_code", "support_code")
 
         if _has_table(db, "proposes") and _has_column(db, "proposes", "propose_code"):
-            db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_proposes_propose_code ON proposes (propose_code)"))
+            _ensure_unique_index(db, "proposes", "idx_proposes_propose_code", "propose_code")
 
         if _has_table(db, "essentials") and _has_column(db, "essentials", "essential_code"):
-            db.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS idx_essentials_essential_code ON essentials (essential_code)"))
+            _ensure_unique_index(db, "essentials", "idx_essentials_essential_code", "essential_code")
 
         # --- server_states nginx telemetry for generic monitor client ---
         if _has_table(db, "server_states") and not _has_column(db, "server_states", "nginx_installed"):