新增: Reviewer仲裁+命令互斥锁+冲突解决IPC(批次C散项)

- coordinator: arbitrate_conflicts 方法(规则仲裁:成功方优先/双方成功推荐合并/都失败手动)

- coordinator: ConflictItem 加 subtask_a/subtask_b/recommendation 字段 + ConflictResolution 枚举

- command_lock.rs: CommandLockRegistry (dir+cmd首词 Semaphore 串行化,5个测试全绿)

- resolve_conflict IPC: 解决冲突→更新DB→emit AiConflictResolved 事件闭环

- 3个仲裁测试 + 5个互斥锁测试全绿

- 零编译警告

src-tauri/src/commands/settings.rs

@@ -140,3 +140,45 @@ pub async fn set_plan_execution(enabled: bool) -> Result<(), String> {
 pub async fn get_plan_execution() -> Result<bool, String> {
     Ok(df_ai::plan_executor::plan_execution_enabled())
 }
+
+/// 解决合并冲突(用户/reviewer 选择解决方案后调用)。
+///
+/// 更新 ai_conflicts 表的 resolution + resolved_by + resolved_at,
+/// 并 emit AiConflictResolved 事件供前端更新徽章。
+#[tauri::command]
+pub async fn resolve_conflict(
+    state: State<'_, AppState>,
+    app_handle: tauri::AppHandle,
+    conflict_id: String,
+    plan_id: String,
+    resolution: String,
+    resolved_by: String,
+    conversation_id: Option<String>,
+) -> Result<(), String> {
+    use tauri::Emitter;
+    let repo = df_storage::crud::ConflictRepo::new(&state.db);
+    let now = df_types::now_millis().to_string();
+    let ok = repo.resolve(&conflict_id, &resolution, &resolved_by, &now)
+        .await
+        .map_err(err_str)?;
+    if !ok {
+        return Err(format!("冲突 {} 不存在或已解决", conflict_id));
+    }
+    tracing::info!(
+        conflict_id = %conflict_id,
+        resolution = %resolution,
+        resolved_by = %resolved_by,
+        "[CONFLICT] 冲突已解决"
+    );
+    // emit AiConflictResolved 事件
+    let ev = crate::commands::ai::AiChatEvent::AiConflictResolved {
+        conflict_id,
+        plan_id,
+        resolution,
+        resolved_by,
+        conversation_id,
+    };
+    let _ = app_handle.emit("ai-chat-event", ev.clone());
+    let _ = state.ai_event_bus.publish_event(ev);
+    Ok(())
+}