fix(tui): preserve drafts when Down is not navigating history (#6219)

README.md

@@ -2391,6 +2391,10 @@ Headless `--print` and `--json` exit with status `1` when the run fails, includi
 
 A keyboard-driven chat surface with a streaming transcript (Markdown-rendered answers), compact tool-activity cards, a `/` slash-command palette, display-only `/clear`, `/goal` goal management, `/model` and `/threads` pickers, input history, PageUp/PageDown transcript navigation, and `Esc` / `Ctrl+C` interrupt. The composer preserves line breaks and indentation in pasted code, stack traces, and multi-paragraph prompts; `Enter` sends the complete document. Transcript refreshes preserve your reading position after you scroll upward and resume following new output when you return to the bottom. `/clear` removes rows from the current terminal display without deleting the thread or its persisted conversation; `/new` and `/clear` ask you to wait during an active run instead of resetting in-flight display state. Sessions opened in the TUI also appear in the Web UI sidebar — it writes the shared thread store under the local default user, so terminal and web stay in sync **without running the Gateway**.
 
+At the last composer row, `Down` leaves an unsent draft untouched unless you are
+browsing input history; after recalling history, it moves forward to restore your
+saved draft.
+
 See [backend/docs/TUI.md](backend/docs/TUI.md) for the full guide.
 
 ## Documentation

backend/docs/TUI.md

@@ -85,6 +85,10 @@ for trusted embedded CLI runs.
 | `Ctrl+C` | Interrupt the active run, or quit when idle |
 | `Ctrl+L` | Redraw · `Ctrl+U` clear composer |
 
+At the last input row, `↓` preserves the current draft unless you are browsing
+history. After `↑` recalls history, `↓` moves forward and restores the saved
+draft when it passes the newest entry.
+
 Transcript updates follow new output while the view is at the bottom. After you
 scroll upward, streaming refreshes preserve the reading position until you
 return to the bottom with `PageDown`.

backend/packages/harness/deerflow/tui/AGENTS.md

@@ -13,4 +13,8 @@ A terminal-native UI over the embedded harness, exposed as the `deerflow` consol
 
 **Web UI visibility**: the Web UI lists threads from the `threads_meta` SQL table (user-scoped), not the checkpointer. `persistence.py` writes a `threads_meta` row under the default user (`"default"`) into the same DB the Gateway reads — via the harness-only `deerflow.persistence.engine.init_engine_from_config()` — so TUI sessions appear in the Web UI sidebar **without** running the Gateway. Best-effort: a no-op on the `memory` backend. All DB work runs on one long-lived background event loop (a SQLAlchemy async engine is bound to its creating loop).
 
+`InputHistory.down()` returns `None` when history navigation is inactive; the
+app must then leave the composer untouched, including its cursor and undo state.
+An empty string is a valid saved draft and must still be restored after history.
+
 **Tests**: `tests/test_tui_*.py` — pure layers via plain pytest, the app/palette/overlays via Textual's pilot harness with a fake in-process session, and `test_tui_persistence.py` for the `threads_meta` round-trip.

backend/packages/harness/deerflow/tui/app.py

@@ -323,7 +323,9 @@ class DeerFlowTUI(App):
         if self._palette_open:
             self.action_palette_down()
         else:
-            self._history_move(self._history.down())
+            value = self._history.down()
+            if value is not None:
+                self._history_move(value)
 
     def _history_move(self, value: str) -> None:
         composer = self.query_one("#composer", ComposerInput)

backend/packages/harness/deerflow/tui/input_history.py

@@ -43,10 +43,10 @@ class InputHistory:
             self._cursor -= 1
         return self._entries[self._cursor]
 
-    def down(self) -> str:
-        """Move one entry newer. Past the newest entry, restores the draft."""
+    def down(self) -> str | None:
+        """Move newer or restore the draft; return None when not navigating."""
         if self._cursor is None:
-            return self._draft
+            return None
         if self._cursor < len(self._entries) - 1:
             self._cursor += 1
             return self._entries[self._cursor]

backend/tests/test_tui_app.py

@@ -624,6 +624,65 @@ async def test_down_on_last_line_of_multiline_input_falls_back_to_history():
         assert composer.value == ""
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize("history", [[], ["previous prompt"]])
+@pytest.mark.parametrize("draft", ["unsent question", "first line\nsecond line"])
+async def test_down_without_history_navigation_preserves_draft_and_cursor(history, draft):
+    app = DeerFlowTUI(_FakeSession(), LaunchPlan(mode="tui"))
+
+    async with app.run_test() as pilot:
+        await pilot.pause()
+        for entry in history:
+            app._history.add(entry)
+        app.post_message(events.Paste(draft))
+        await pilot.pause()
+        composer = app.query_one("#composer")
+        location = (len(draft.splitlines()) - 1, 2)
+        composer.move_cursor(location)
+
+        await pilot.press("down", "down")
+        await pilot.pause()
+        assert composer.value == draft
+        assert composer.cursor_location == location
+        await pilot.press("ctrl+z")
+        await pilot.pause()
+        assert composer.value == ""
+
+
+@pytest.mark.asyncio
+async def test_history_round_trip_restores_draft_and_idle_down_keeps_later_edits():
+    app = DeerFlowTUI(_FakeSession(), LaunchPlan(mode="tui"))
+    draft = "first line\nsecond line"
+
+    async with app.run_test() as pilot:
+        await pilot.pause()
+        app._history.add("older prompt")
+        app._history.add("newer prompt")
+        app.post_message(events.Paste(draft))
+        await pilot.pause()
+        composer = app.query_one("#composer")
+        composer.cursor_position = 0
+
+        await pilot.press("up")
+        await pilot.pause()
+        assert composer.value == "newer prompt"
+        await pilot.press("up")
+        await pilot.pause()
+        assert composer.value == "older prompt"
+        await pilot.press("down")
+        await pilot.pause()
+        assert composer.value == "newer prompt"
+        await pilot.press("down")
+        await pilot.pause()
+        assert composer.value == draft
+
+        app.post_message(events.Paste(" edited"))
+        await pilot.pause()
+        await pilot.press("down")
+        await pilot.pause()
+        assert composer.value == draft + " edited"
+
+
 @pytest.mark.asyncio
 async def test_slash_command_with_surrounding_whitespace_still_runs_as_command():
     session = _FakeSession()

backend/tests/test_tui_input_history.py

@@ -1,5 +1,7 @@
 """Tests for bounded composer input history (pure)."""
 
+import pytest
+
 from deerflow.tui.input_history import InputHistory
 
 
@@ -48,6 +50,20 @@ def test_down_walks_forward_then_restores_draft():
     assert h.down() == "my draft"  # past newest -> stashed draft
 
 
+@pytest.mark.parametrize("entries", [[], ["previous prompt"]])
+def test_down_without_history_navigation_returns_no_change(entries):
+    h = InputHistory(entries)
+    assert h.down() is None
+
+
+@pytest.mark.parametrize("draft", ["", "first line\nsecond line"])
+def test_down_restores_draft_once_and_then_stops(draft):
+    h = InputHistory(["previous prompt"])
+    assert h.up(draft) == "previous prompt"
+    assert h.down() == draft
+    assert h.down() is None
+
+
 def test_up_with_empty_history_returns_draft():
     h = InputHistory()
     assert h.up(draft="keep") == "keep"