feat: add preview table to batch tab UI

Add gr.Dataframe component to the Batch tab so translate_batch() results
display as a preview table alongside the downloadable file.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -231,14 +231,16 @@ def _build_demo() -> gr.Blocks:
                 with gr.Tab("Batch"):
                     gr.Markdown("Upload a `.txt` file (one sentence per line) or a `.csv` file with a `text` column.")
                     batch_input = gr.File(label="Upload file", file_types=[".txt", ".csv"])
-                    batch_output = gr.File(label="Download translations", interactive=False)
 
                     batch_btn = gr.Button("Translate", variant="primary")
 
+                    batch_preview = gr.Dataframe(label="Preview", interactive=False)
+                    batch_output = gr.File(label="Download translations", interactive=False)
+
                     batch_btn.click(
                         fn=translate_batch,
                         inputs=[batch_input, target_language, max_new_tokens, num_beams, temperature],
-                        outputs=batch_output,
+                        outputs=[batch_preview, batch_output],
                     )
 
     return demo

tests/test_app.py

@@ -313,6 +313,22 @@ def test_build_table_data_csv():
     assert result["data"] == [["1", "Hello", "Bonjour"]]
 
 
+# --- Batch tab Dataframe tests ---
+
+
+def test_demo_has_dataframe_component(demo):
+    """Batch tab should contain a Dataframe component for preview."""
+    dataframes = [b for b in demo.blocks.values() if type(b).__name__ == "Dataframe"]
+    assert len(dataframes) >= 1, "Expected at least one Dataframe component"
+
+
+def test_dataframe_is_non_interactive(demo):
+    """Batch preview Dataframe should be non-interactive."""
+    dataframes = [b for b in demo.blocks.values() if type(b).__name__ == "Dataframe"]
+    assert len(dataframes) >= 1
+    assert dataframes[0].interactive is False
+
+
 # --- UI component tests ---