fix: migrate proxy_config singleton to per-app on startup for v2 databases

Add startup migration for legacy proxy_config tables that still have
singleton structure (no app_type column) even with user_version=2.

This fixes the issue where v3.9.0-2 databases with v2 schema but legacy
proxy_config structure would fail with "no such column: app_type" error.

- Call migrate_proxy_config_to_per_app in create_tables_on_conn
- Add regression test to verify the fix

src-tauri/src/database/schema.rs

@@ -265,6 +265,14 @@ impl Database {
             [],
         );
 
+        // 兼容：若旧版 proxy_config 仍为单例结构（无 app_type），则在启动时直接转换为三行结构
+        // 说明：user_version=2 时不会再触发 v1->v2 迁移，但新代码查询依赖 app_type 列。
+        if Self::table_exists(conn, "proxy_config")?
+            && !Self::has_column(conn, "proxy_config", "app_type")?
+        {
+            Self::migrate_proxy_config_to_per_app(conn)?;
+        }
+
         // 确保 in_failover_queue 列存在（对于已存在的 v2 数据库）
         Self::add_column_if_missing(
             conn,

src-tauri/src/database/tests.rs

@@ -201,6 +201,53 @@ fn migration_aligns_column_defaults_and_types() {
     );
 }
 
+#[test]
+fn create_tables_repairs_legacy_proxy_config_singleton_to_per_app() {
+    let conn = Connection::open_in_memory().expect("open memory db");
+
+    // 模拟测试版 v2：user_version=2，但 proxy_config 仍是单例结构（无 app_type）
+    Database::set_user_version(&conn, 2).expect("set user_version");
+    conn.execute_batch(
+        r#"
+        CREATE TABLE proxy_config (
+            id INTEGER PRIMARY KEY,
+            enabled INTEGER NOT NULL DEFAULT 0,
+            listen_address TEXT NOT NULL DEFAULT '127.0.0.1',
+            listen_port INTEGER NOT NULL DEFAULT 5000,
+            max_retries INTEGER NOT NULL DEFAULT 3,
+            request_timeout INTEGER NOT NULL DEFAULT 300,
+            enable_logging INTEGER NOT NULL DEFAULT 1,
+            target_app TEXT NOT NULL DEFAULT 'claude',
+            created_at TEXT NOT NULL DEFAULT (datetime('now')),
+            updated_at TEXT NOT NULL DEFAULT (datetime('now'))
+        );
+        INSERT INTO proxy_config (id, enabled) VALUES (1, 1);
+        "#,
+    )
+    .expect("seed legacy proxy_config");
+
+    Database::create_tables_on_conn(&conn).expect("create tables should repair proxy_config");
+
+    assert!(
+        Database::has_column(&conn, "proxy_config", "app_type").expect("check app_type"),
+        "proxy_config should be migrated to per-app structure"
+    );
+
+    let count: i32 = conn
+        .query_row("SELECT COUNT(*) FROM proxy_config", [], |r| r.get(0))
+        .expect("count rows");
+    assert_eq!(count, 3, "per-app proxy_config should have 3 rows");
+
+    // 新结构下应能按 app_type 查询
+    let _: i32 = conn
+        .query_row(
+            "SELECT COUNT(*) FROM proxy_config WHERE app_type = 'claude'",
+            [],
+            |r| r.get(0),
+        )
+        .expect("query by app_type");
+}
+
 #[test]
 fn dry_run_does_not_write_to_disk() {
     // Create minimal valid config for migration