feat(db): rebuild Codex usage on upgrade and via maintenance action

Schema v16 wipes codex_session detail rows, _codex_session rollups and
Codex rollout cursors inside the migration savepoint (cursor deletion
uses pure shape matching so CODEX_HOME drift cannot orphan cursors);
the next session sync re-imports history from source JSONL under the
corrected importer. Fresh installs traverse the same branch as a no-op.

Add a manual "Rebuild Codex usage" maintenance action (single-flight,
hard-fail backup before reset, unconditional refresh notification even
when reimport is empty or fails after reset) with a destructive confirm
dialog, result toast and four-locale strings. Historical proxy-side
duplicate rows are intentionally left untouched; history whose source
JSONL was already deleted cannot be reconstructed.

src-tauri/src/commands/usage.rs

@@ -289,6 +289,35 @@ pub async fn sync_session_usage(
     .map_err(|error| AppError::Message(format!("会话用量同步任务失败: {error}")))
 }
 
+/// Codex reset 成功后，无论重导是否导入新行或返回错误，都必须通知前端刷新。
+/// 调用方应只在 reset 成功后调用，避免把未发生的数据变更误报为重建完成。
+fn finish_codex_rebuild(
+    result: Result<crate::services::session_usage::SessionSyncResult, AppError>,
+) -> Result<crate::services::session_usage::SessionSyncResult, AppError> {
+    crate::usage_events::notify_log_recorded();
+    result
+}
+
+/// 备份数据库后，仅重建 Codex session 用量。锁覆盖 backup → reset → import
+/// 整个序列，避免后台同步在清理和重导之间插入数据。
+#[tauri::command]
+pub async fn rebuild_codex_usage(
+    state: State<'_, AppState>,
+) -> Result<crate::services::session_usage::SessionSyncResult, AppError> {
+    let db = state.db.clone();
+    let _guard = crate::services::session_usage::session_sync_mutex()
+        .lock()
+        .await;
+    tauri::async_runtime::spawn_blocking(move || {
+        db.backup_database_file()?;
+        db.reset_codex_usage()?;
+        let result = crate::services::session_usage_codex::sync_codex_usage(&db);
+        finish_codex_rebuild(result)
+    })
+    .await
+    .map_err(|error| AppError::Message(format!("Codex 用量重建任务失败: {error}")))?
+}
+
 /// 获取数据来源分布
 #[tauri::command]
 pub fn get_usage_data_sources(
@@ -308,3 +337,33 @@ pub struct ModelPricingInfo {
     pub cache_read_cost_per_million: String,
     pub cache_creation_cost_per_million: String,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn codex_rebuild_notifies_when_reimport_is_empty() {
+        crate::usage_events::take_test_notify_count();
+
+        let result = finish_codex_rebuild(Ok(
+            crate::services::session_usage::SessionSyncResult::default(),
+        ))
+        .expect("空重导应成功");
+
+        assert_eq!(result.imported, 0);
+        assert_eq!(crate::usage_events::take_test_notify_count(), 1);
+    }
+
+    #[test]
+    fn codex_rebuild_notifies_when_reimport_fails_after_reset() {
+        crate::usage_events::take_test_notify_count();
+
+        let result = finish_codex_rebuild(Err(AppError::Message(
+            "synthetic reimport failure".to_string(),
+        )));
+
+        assert!(result.is_err());
+        assert_eq!(crate::usage_events::take_test_notify_count(), 1);
+    }
+}

src-tauri/src/database/mod.rs

@@ -52,7 +52,7 @@ use std::sync::Mutex;
 
 /// 当前 Schema 版本号
 /// 每次修改表结构时递增，并在 schema.rs 中添加相应的迁移逻辑
-pub(crate) const SCHEMA_VERSION: i32 = 15;
+pub(crate) const SCHEMA_VERSION: i32 = 16;
 
 /// 安全地序列化 JSON，避免 unwrap panic
 pub(crate) fn to_json_string<T: Serialize>(value: &T) -> Result<String, AppError> {

src-tauri/src/database/schema.rs

@@ -506,6 +506,11 @@ impl Database {
                         Self::migrate_v14_to_v15(conn)?;
                         Self::set_user_version(conn, 15)?;
                     }
+                    15 => {
+                        log::info!("迁移数据库从 v15 到 v16（重建 Codex 会话用量）");
+                        Self::migrate_v15_to_v16(conn)?;
+                        Self::set_user_version(conn, 16)?;
+                    }
                     _ => {
                         return Err(AppError::Database(format!(
                             "未知的数据库版本 {version}，无法迁移到 {SCHEMA_VERSION}"
@@ -1510,6 +1515,14 @@ impl Database {
         Ok(())
     }
 
+    /// v15 -> v16: remove Codex session rows and cursors so startup sync can
+    /// rebuild them with fork-history alignment. Must stay connection-level:
+    /// schema migration already owns the Database connection mutex.
+    fn migrate_v15_to_v16(conn: &Connection) -> Result<(), AppError> {
+        let codex_dir = crate::codex_config::get_codex_config_dir();
+        crate::services::session_usage_codex::reset_codex_usage_on_conn(conn, &codex_dir)
+    }
+
     /// 插入默认模型定价数据
     /// 格式: (model_id, display_name, input, output, cache_read, cache_creation)
     /// 注意: model_id 使用短横线格式（如 claude-haiku-4-5），与 API 返回的模型名称标准化后一致
@@ -3025,4 +3038,44 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn migrate_v15_to_v16_resets_only_codex_session_usage() -> Result<(), AppError> {
+        let conn = Connection::open_in_memory()?;
+        Database::create_tables_on_conn(&conn)?;
+        conn.execute_batch(
+            "INSERT INTO proxy_request_logs (
+                request_id, provider_id, app_type, model, input_tokens,
+                output_tokens, cache_read_tokens, latency_ms, status_code,
+                created_at, data_source
+             ) VALUES
+                ('codex-row', '_codex_session', 'codex', 'gpt', 1, 1, 0, 0, 200, 1, 'codex_session'),
+                ('gemini-row', '_gemini_session', 'gemini', 'gemini', 1, 1, 0, 0, 200, 1, 'gemini_session');
+             INSERT INTO usage_daily_rollups (date, app_type, provider_id, model)
+             VALUES
+                ('2026-07-10', 'codex', '_codex_session', 'gpt'),
+                ('2026-07-10', 'gemini', '_gemini_session', 'gemini');
+             INSERT INTO session_log_sync
+                (file_path, last_modified, last_line_offset, last_synced_at)
+             VALUES
+                ('/old/sessions/rollout-old-00000000-0000-4000-8000-000000000001.jsonl', 1, 1, 1),
+                ('/gemini/tmp/session-123.json', 1, 1, 1);",
+        )?;
+        Database::set_user_version(&conn, 15)?;
+
+        Database::apply_schema_migrations_on_conn(&conn)?;
+
+        assert_eq!(Database::get_user_version(&conn)?, 16);
+        let counts: (i64, i64, i64, i64) = conn.query_row(
+            "SELECT
+                (SELECT COUNT(*) FROM proxy_request_logs WHERE data_source = 'codex_session'),
+                (SELECT COUNT(*) FROM proxy_request_logs WHERE data_source = 'gemini_session'),
+                (SELECT COUNT(*) FROM usage_daily_rollups WHERE provider_id = '_codex_session'),
+                (SELECT COUNT(*) FROM session_log_sync)",
+            [],
+            |row| Ok((row.get(0)?, row.get(1)?, row.get(2)?, row.get(3)?)),
+        )?;
+        assert_eq!(counts, (0, 1, 0, 1));
+        Ok(())
+    }
 }

src-tauri/src/lib.rs

@@ -1522,6 +1522,7 @@ pub fn run() {
             commands::check_provider_limits,
             // Session usage sync
             commands::sync_session_usage,
+            commands::rebuild_codex_usage,
             commands::get_usage_data_sources,
             // Stream health check
             commands::stream_check_provider,