diff --git a/clients/terminal/tui/widgets/input_box.py b/clients/terminal/tui/widgets/input_box.py
index 5b42cdf..2c1fe7f 100644
--- a/clients/terminal/tui/widgets/input_box.py
+++ b/clients/terminal/tui/widgets/input_box.py
@@ -1,16 +1,47 @@
-"""Input box widget for the TUI."""
+"""Input box widget for the TUI.
+
+A multi-line prompt: ``Enter`` sends the message, ``Ctrl+Enter`` inserts a hard
+line break, and long lines soft-wrap visually (``TextArea`` defaults to
+``soft_wrap=True``). The field grows with content up to ``max-height`` and then
+scrolls internally.
+"""
 
 from __future__ import annotations
 
+from textual import events
 from textual.app import ComposeResult
 from textual.containers import Vertical
-from textual.widgets import Input
+from textual.widgets import TextArea
 
 from clients.terminal.tui.events import UserSubmitted
 
 
+class _PromptInput(TextArea):
+    """Multi-line text area that submits on Enter and breaks on Ctrl+Enter."""
+
+    async def _on_key(self, event: events.Key) -> None:
+        # Intercept before TextArea's own _on_key, which maps "enter" -> "\n".
+        if event.key == "enter":
+            event.stop()
+            event.prevent_default()
+            self.action_submit()
+            return
+        if event.key == "ctrl+enter":
+            event.stop()
+            event.prevent_default()
+            self.insert("\n")
+            return
+        await super()._on_key(event)
+
+    def action_submit(self) -> None:
+        text = self.text
+        if text.strip():
+            self.post_message(UserSubmitted(text))
+        self.text = ""
+
+
 class InputBox(Vertical):
-    """Bottom prompt frame with input field."""
+    """Bottom prompt frame with a multi-line input field."""
 
     DEFAULT_CSS = """
     InputBox {
@@ -21,35 +52,31 @@
         color: $tui-text;
         padding: 0 1;
     }
-    InputBox > Input {
-        height: 3;
+    InputBox > TextArea {
+        height: auto;
+        min-height: 3;
+        max-height: 12;
         width: 100%;
         border: none;
         background: $tui-surface;
         color: $tui-text;
         padding: 0;
     }
-    InputBox > Input:focus {
+    InputBox > TextArea:focus {
         border: none;
         background-tint: transparent;
     }
-    InputBox > Input > .input--placeholder {
-        color: $tui-text-dim;
-    }
-    InputBox > Input > .input--cursor {
-        background: $tui-text;
-        color: $tui-background;
-        text-style: bold;
-    }
-    InputBox > Input > .input--selection {
-        background: $tui-selection;
-        color: $tui-background;
-    }
     """
 
     def __init__(self) -> None:
         super().__init__()
-        self._input = Input(placeholder="Ask anything...", classes="input-field")
+        self._input = _PromptInput(
+            text="",
+            placeholder="Ask anything... (Enter to send, Ctrl+Enter for a new line)",
+            classes="input-field",
+            show_line_numbers=False,
+            soft_wrap=True,
+        )
 
     def compose(self) -> ComposeResult:
         yield self._input
@@ -57,20 +84,8 @@
     def on_mount(self) -> None:
         self._input.focus()
 
-    def on_input_changed(self, event: Input.Changed) -> None:
-        self._input.refresh(layout=False)
-
-    def on_input_submitted(self, event: Input.Submitted) -> None:
-        text = event.value.strip()
-        if text:
-            self.post_message(UserSubmitted(text))
-            self._input.value = ""
-
     def focus_input(self) -> None:
         self._input.focus()
 
     def set_placeholder(self, text: str) -> None:
-        self._input.placeholder = text
-
-    def set_prompt_char(self, char: str) -> None:
-        self._prompt.update(char)
+        self._input.placeholder = text
\ No newline at end of file
diff --git a/tests/clients/test_tui_app.py b/tests/clients/test_tui_app.py
index 0b4201d..8e9fdb7 100644
--- a/tests/clients/test_tui_app.py
+++ b/tests/clients/test_tui_app.py
@@ -68,7 +68,7 @@
     async with NaviCodeTui(new_session=True).run_test() as pilot:
         await pilot.pause()
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "hello"
+        input_box._input.text = "hello"
         await pilot.press("enter")
         await pilot.pause()
         chat = pilot.app.query_one("ChatPanel")
@@ -86,7 +86,7 @@
         input_box._input.focus()
         await pilot.press("h", "i", " ", "n", "a", "v", "i")
         await pilot.pause()
-        assert input_box._input.value == "hi navi"
+        assert input_box._input.text == "hi navi"
         strip = input_box._input.render_line(0)
         segments = list(strip)
         rendered_text = "".join(seg.text for seg in segments)
@@ -98,6 +98,59 @@
 
 
 @pytest.mark.anyio
+async def test_ctrl_enter_inserts_newline_without_submitting() -> None:
+    """Ctrl+Enter inserts a hard line break; Enter is what submits."""
+    async with NaviCodeTui(new_session=True).run_test() as pilot:
+        await pilot.pause()
+        input_box = pilot.app.query_one("InputBox")
+        input_box._input.focus()
+        await pilot.press("h", "i")
+        await pilot.press("ctrl+enter")
+        await pilot.press("t", "h", "e", "r", "e")
+        await pilot.pause()
+        # A newline was inserted, not submitted.
+        assert input_box._input.text == "hi\nthere"
+        chat = pilot.app.query_one("ChatPanel")
+        assert not any(
+            item.kind == "user_message" for item in chat._model.items
+        )
+
+
+@pytest.mark.anyio
+async def test_enter_submits_multiline_text() -> None:
+    """Enter submits the full multi-line buffer (newlines preserved)."""
+    async with NaviCodeTui(new_session=True).run_test() as pilot:
+        await pilot.pause()
+        input_box = pilot.app.query_one("InputBox")
+        input_box._input.text = "line one\nline two"
+        input_box._input.focus()
+        await pilot.press("enter")
+        await pilot.pause()
+        chat = pilot.app.query_one("ChatPanel")
+        submitted = [
+            item.content
+            for item in chat._model.items
+            if item.kind == "user_message"
+        ]
+        assert submitted == ["line one\nline two"]
+        # Input is cleared after submit.
+        assert input_box._input.text == ""
+
+
+@pytest.mark.anyio
+async def test_input_grows_with_multiline_content() -> None:
+    """The input field height grows with content (multi-line), up to a cap."""
+    async with NaviCodeTui(new_session=True).run_test() as pilot:
+        await pilot.pause()
+        input_box = pilot.app.query_one("InputBox")
+        single = input_box._input.region.height
+        input_box._input.text = "a\nb\nc\nd\ne\nf"
+        await pilot.pause()
+        grown = input_box._input.region.height
+        assert grown > single
+
+
+@pytest.mark.anyio
 async def test_ws_event_renders_in_chat() -> None:
     """A synthetic WebSocket stream_delta is added to the assistant response."""
     async with NaviCodeTui(new_session=True).run_test() as pilot:
@@ -187,7 +240,7 @@
     async with NaviCodeTui(new_session=True).run_test() as pilot:
         await pilot.pause()
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/notacommand"
+        input_box._input.text = "/notacommand"
         await pilot.press("enter")
         await pilot.pause()
         chat = pilot.app.query_one("ChatPanel")
diff --git a/tests/clients/test_tui_export.py b/tests/clients/test_tui_export.py
index 6f9eac6..d97ce0e 100644
--- a/tests/clients/test_tui_export.py
+++ b/tests/clients/test_tui_export.py
@@ -75,7 +75,7 @@
     async with NaviCodeTui(new_session=True).run_test() as pilot:
         await pilot.pause()
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/export"
+        input_box._input.text = "/export"
         await pilot.press("enter")
         await pilot.pause()
 
@@ -110,7 +110,7 @@
         await pilot.pause()
         pilot.app._ctx.session_id = None
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/export"
+        input_box._input.text = "/export"
         await pilot.press("enter")
         await pilot.pause()
         chat = pilot.app.query_one("ChatPanel")
@@ -133,7 +133,7 @@
     async with NaviCodeTui(new_session=True).run_test() as pilot:
         await pilot.pause()
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/export"
+        input_box._input.text = "/export"
         await pilot.press("enter")
         await pilot.pause()
         chat = pilot.app.query_one("ChatPanel")
diff --git a/tests/clients/test_tui_themes.py b/tests/clients/test_tui_themes.py
index ae134b7..c2749f2 100644
--- a/tests/clients/test_tui_themes.py
+++ b/tests/clients/test_tui_themes.py
@@ -29,7 +29,7 @@
     async with NaviCodeTui(new_session=True).run_test() as pilot:
         await pilot.pause()
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/themes"
+        input_box._input.text = "/themes"
         await pilot.press("enter")
         await pilot.pause()
         assert pilot.app.screen.__class__.__name__ == "ThemePickerScreen"
@@ -40,7 +40,7 @@
     async with NaviCodeTui(new_session=True).run_test() as pilot:
         await pilot.pause()
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/themes"
+        input_box._input.text = "/themes"
         await pilot.press("enter")
         await pilot.pause()
         assert pilot.app.screen.__class__.__name__ == "ThemePickerScreen"
@@ -59,7 +59,7 @@
         tui_settings = get_tui_settings()
         original = tui_settings.mouse
         input_box = pilot.app.query_one("InputBox")
-        input_box._input.value = "/mouse"
+        input_box._input.text = "/mouse"
         await pilot.press("enter")
         await pilot.pause()
         assert tui_settings.mouse is not original