fix(api): use processed_file_path from DB in upload retry path resolution

The upload retry logic now checks file_record.processed_file_path first
(the GPT-suggested filename stored during finalization), before falling
back to legacy hash-based and original-filename-based path patterns.

This fixes the case where the processed file has a different name than
the original (e.g., '2023-10-01_Unknown.pdf' vs 'cable_graphic.pdf')
and the retry couldn't find the file on disk.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

tests/test_retry_subtask_logging.py

@@ -168,6 +168,7 @@ class TestRetrySubtaskEnhancedLogging:
             filehash="upload_error_test",
             original_filename="missing.pdf",
             local_filename="/nonexistent/tmp/missing.pdf",
+            processed_file_path="/nonexistent/processed/missing_gpt.pdf",
             file_size=1024,
             mime_type="application/pdf",
         )
@@ -183,8 +184,82 @@ class TestRetrySubtaskEnhancedLogging:
         # Verify the error message contains diagnostic information
         assert "Cannot retry upload" in error_detail
         assert "Paths checked:" in error_detail
+        assert "processed_file_path" in error_detail
         assert "exists=False" in error_detail
 
+    def test_upload_retry_uses_processed_file_path_from_db(
+        self, client: TestClient, db_session, sample_pdf_path, tmp_path
+    ):
+        """Test that upload retry uses processed_file_path from DB when legacy paths don't exist."""
+        mock_task = MagicMock()
+        mock_task.id = "upload-processed-path-task"
+
+        # Create processed file at the DB-stored path (GPT-suggested filename)
+        processed_file = tmp_path / "2023-10-01_Unknown.pdf"
+        shutil.copy(sample_pdf_path, processed_file)
+
+        # Create file record where only processed_file_path exists
+        # (simulates the real scenario: original filename != GPT-suggested filename)
+        file_record = FileRecord(
+            filehash="upload_db_path_test",
+            original_filename="cable_graphic.pdf",
+            local_filename="/nonexistent/tmp/uuid.pdf",
+            processed_file_path=str(processed_file),
+            file_size=1024,
+            mime_type="application/pdf",
+        )
+        db_session.add(file_record)
+        db_session.commit()
+        db_session.refresh(file_record)
+
+        with patch("app.tasks.upload_to_onedrive.upload_to_onedrive") as mock_upload:
+            mock_upload.delay.return_value = mock_task
+            response = client.post(f"/api/files/{file_record.id}/retry-subtask?subtask_name=upload_to_onedrive")
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["status"] == "success"
+        assert data["subtask_name"] == "upload_to_onedrive"
+
+        # Verify the task was called with the processed_file_path from DB
+        mock_upload.delay.assert_called_once()
+        call_args = mock_upload.delay.call_args
+        assert call_args[0][0] == str(processed_file)
+
+    def test_upload_retry_processed_file_path_takes_priority(
+        self, client: TestClient, db_session, sample_pdf_path, tmp_path
+    ):
+        """Test that processed_file_path from DB takes priority over legacy hash-based paths."""
+        mock_task = MagicMock()
+        mock_task.id = "upload-priority-task"
+
+        # Create the DB-stored processed file
+        processed_file = tmp_path / "2024-01-01_Invoice.pdf"
+        shutil.copy(sample_pdf_path, processed_file)
+
+        file_record = FileRecord(
+            filehash="upload_priority_test",
+            original_filename="scan001.pdf",
+            local_filename="/nonexistent/tmp/uuid.pdf",
+            processed_file_path=str(processed_file),
+            file_size=1024,
+            mime_type="application/pdf",
+        )
+        db_session.add(file_record)
+        db_session.commit()
+        db_session.refresh(file_record)
+
+        with patch("app.tasks.upload_to_dropbox.upload_to_dropbox") as mock_upload:
+            mock_upload.delay.return_value = mock_task
+            response = client.post(f"/api/files/{file_record.id}/retry-subtask?subtask_name=upload_to_dropbox")
+
+        assert response.status_code == 200
+
+        # Verify the task was called with the processed_file_path (first priority for uploads)
+        mock_upload.delay.assert_called_once()
+        call_args = mock_upload.delay.call_args
+        assert call_args[0][0] == str(processed_file)
+
     def test_embed_metadata_path_order(self, client: TestClient, db_session, sample_pdf_path, tmp_path):
         """Test that embed_metadata_into_pdf checks paths in the correct order."""
         mock_task = MagicMock()