Phase 2：修復 Bug2——格式驗證失敗後可重新上傳

- run_format_check 失敗分支改為只清除驗證失敗的檔案，保留已通過的
- on_upload_confirm 失敗分支的 upload_row 改回 visible=True（原本寫死
False 導致使用者被要求重傳卻沒有上傳欄位可用）
- handle_uploaded_files 改成依檔名合併新舊上傳清單而非整批覆蓋，
否則前兩項修復會在下一次上傳時被覆蓋掉、無法真正只補傳壞檔

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app_agent.py

@@ -1468,7 +1468,13 @@ def handle_uploaded_files(files, state: dict):
         shutil.copy2(str(src), str(dst))
         saved_paths.append(str(dst))
 
-    state["uploaded_files"] = saved_paths
+    # 格式驗證失敗時只會清掉不合格的檔案（見 run_format_check），這裡補傳
+    # 要跟先前保留下來、已通過驗證的檔案合併，而不是整批覆蓋掉，使用者才
+    # 只需要補傳有問題的那幾個檔案，同名檔案則視為修正版本直接取代舊的
+    existing = state.get("uploaded_files", [])
+    new_names = {Path(p).name for p in saved_paths}
+    merged_paths = [p for p in existing if Path(p).name not in new_names] + saved_paths
+    state["uploaded_files"] = merged_paths
     state["state"] = "FORMAT_CHECK"
 
     # 工作程序 Agent 說明開始檢查
@@ -1530,7 +1536,8 @@ def run_format_check(state: dict):
             "請使用 [ckip_segmentation_sumin](https://github.com/suhsiung/ckip_segmentation_sumin) "
             "工具完成斷詞後，重新上傳檔案。"
         )
-    state["uploaded_files"] = []
+    failed_names = set(failed.keys())
+    state["uploaded_files"] = [fp for fp in state["uploaded_files"] if Path(fp).name not in failed_names]
     state["state"] = "UPLOAD_WAIT"
     return msg, state, True
 
@@ -3227,7 +3234,7 @@ def create_app():
             if has_errors:
                 log_history = _log_append(log_history, "⚠️ STEP 4 格式不符，請重新上傳")
                 state["current_step"] = 3
-                yield chat_history, log_history, state, gr.update(visible=False), _todo_update(state)
+                yield chat_history, log_history, state, gr.update(visible=True), _todo_update(state)
                 return
 
             state["done_steps"] = list(set(state.get("done_steps", []) + [4]))