feat: help menu in tui

3 files changed, 171 insertions, 48 deletions

diff --git a/app/tests/test_backends.py b/app/tests/test_backends.py
index d4534fb..a49a2f2 100644
--- a/app/tests/test_backends.py
+++ b/app/tests/test_backends.py
@@ -650,7 +650,7 @@ class QwenModelsScreenTests(unittest.TestCase):
             ("Install Base", ("install", "Base")),
             ("Install VoiceDesign", ("install", "VoiceDesign")),
         ])
-        self.assertEqual(kwargs["table_title"], "Model state")
+        self.assertEqual(kwargs["table_title"], "Model State")
         self.assertEqual(kwargs["table_rows"][0],
                          ("CustomVoice", "installed", "ok"))
 
@@ -707,7 +707,7 @@ class QwenModelsScreenTests(unittest.TestCase):
         # No task-view run, one guidance flash instead of a download.
         self.assertEqual(runs, [])
         guidance = ("Install the qwen-tts backend first "
-                    "(Configure backends > Install Backend).")
+                    "(Configure Backends > Install Backend).")
         self.assertEqual(flashes, [(guidance, "warn")])
         # While the backend is missing, Install is replaced by dimmed-out
         # "(backend not installed)" placeholders — actions stay inert.
diff --git a/app/tests/test_hub.py b/app/tests/test_hub.py
index 4186c92..798c27f 100644
--- a/app/tests/test_hub.py
+++ b/app/tests/test_hub.py
@@ -143,9 +143,11 @@ class HubMenuTests(unittest.TestCase):
         return BackendStatus(key, label, installed=False, configured=False)
 
     def test_quit_returns_none_when_no_backend(self):
-        # No backends installed/running: menu is [Configure backends,
-        # Settings, Quit]. Quit is the 3rd option (Down twice) then Enter.
-        screen = FakeScreen(keys=[FakeCurses.KEY_DOWN, FakeCurses.KEY_DOWN, 10])
+        # No backends installed/running: menu is [Configure Backends,
+        # Settings, Help, Quit]. Quit is the 4th option (Down x3) then
+        # Enter.
+        screen = FakeScreen(keys=[FakeCurses.KEY_DOWN, FakeCurses.KEY_DOWN,
+                                  FakeCurses.KEY_DOWN, 10])
         with patch.object(hub, "detect_all", return_value=[]):
             result = hub._Hub(screen).run()
         self.assertIsNone(result)
@@ -190,7 +192,8 @@ class HubMenuTests(unittest.TestCase):
                 patch.object(hub, "detect_all", return_value=[]):
             hub._Hub(screen).run()
         labels = [label for label, _ in captured["options"]]
-        self.assertEqual(labels, ["Configure backends", "Settings", "Quit"])
+        self.assertEqual(labels,
+                         ["Configure Backends", "Settings", "Help", "Quit"])
 
     def test_menu_has_all_five_when_one_installed(self):
         captured = {}
@@ -209,8 +212,8 @@ class HubMenuTests(unittest.TestCase):
         labels = [label for label, _ in captured["options"]]
         self.assertEqual(
             labels,
-            ["Generate audiobooks", "Configure backends",
-             "Start/Stop Backend Servers", "Settings", "Quit"])
+            ["Generate Audiobooks", "Configure Backends",
+             "Start/Stop Backend Servers", "Settings", "Help", "Quit"])
         # The status table is passed through, one row per backend.
         self.assertEqual(captured["rows"],
                          [("qwen-tts", "installed", "ok", "body")])
@@ -256,8 +259,8 @@ class HubMenuTests(unittest.TestCase):
         labels = [label for label, _ in captured["options"]]
         self.assertEqual(
             labels,
-            ["Generate audiobooks", "Configure backends", "Settings",
-             "Quit"])
+            ["Generate Audiobooks", "Configure Backends", "Settings",
+             "Help", "Quit"])
 
     def test_ffmpeg_warning_shown_when_missing(self):
         # ffmpeg not on PATH → a red notice is passed above the table.
@@ -293,8 +296,8 @@ class HubMenuTests(unittest.TestCase):
     def test_convert_with_no_available_backend_flashes(self):
         # Installed-but-not-ready backends → Convert is offered, but the
         # convert flow has nothing to list: it flashes a hint (no "Configure
-        # backends" detour anymore) and returns to the main menu. Then
-        # quit: 5 main-menu options, Quit is the 5th (Down x4).
+        # Backends" detour anymore) and returns to the main menu. Then
+        # quit: 6 main-menu options, Quit is the 6th (Down x5).
         from backends import BackendStatus
         statuses = [BackendStatus("audiocpp", "audio.cpp", installed=True,
                                   configured=False),
@@ -309,16 +312,54 @@ class HubMenuTests(unittest.TestCase):
 
         with patch.object(hub, "detect_all", return_value=statuses), \
                 patch.object(hub.tui, "flash", fake_flash):
-            # Convert(Enter) → flash → main menu; Down x4 -> Quit, Enter.
+            # Convert(Enter) → flash → main menu; Down x5 -> Quit, Enter.
             screen = FakeScreen(keys=[10,
                                       FakeCurses.KEY_DOWN, FakeCurses.KEY_DOWN,
                                       FakeCurses.KEY_DOWN, FakeCurses.KEY_DOWN,
+                                      FakeCurses.KEY_DOWN,
                                       10])
             result = hub._Hub(screen).run()
         self.assertIsNone(result)
         self.assertEqual(len(flashed), 1)
         self.assertIn("No backend is ready", flashed[0])
 
+    def test_help_opens_viewer_and_backs_out(self):
+        # Selecting Help opens the text viewer with the quick-start text
+        # (real folder paths); closing it lands back on the main menu.
+        calls = []
+
+        def fake_viewer(stdscr, title, lines, **kwargs):
+            calls.append((title, list(lines), kwargs))
+            return kwargs.get("back_value")
+
+        with patch.object(hub, "detect_all", return_value=[]), \
+                patch.object(hub.tui, "text_viewer", fake_viewer):
+            # Help is the 3rd main-menu option (Down x2), then Enter;
+            # back on the main menu Quit is the 4th (Down x3), Enter.
+            screen = FakeScreen(keys=[FakeCurses.KEY_DOWN, FakeCurses.KEY_DOWN,
+                                      10,
+                                      FakeCurses.KEY_DOWN, FakeCurses.KEY_DOWN,
+                                      FakeCurses.KEY_DOWN,
+                                      10])
+            result = hub._Hub(screen).run()
+        self.assertIsNone(result)
+        self.assertEqual(len(calls), 1)
+        title, lines, kwargs = calls[0]
+        self.assertEqual(title, "Help")
+        self.assertIs(kwargs.get("back_value"), tui.Wizard.BACK)
+        text = "\n".join(lines)
+        self.assertIn("1. Put your ebooks (epub, txt, or pdf) here:", text)
+        self.assertIn(str(hub.BOOKS_FOLDER), text)
+        self.assertIn("2. Put any .wavs of voices to clone here:", text)
+        self.assertIn(str(hub.common.VOICES_DIR), text)
+        self.assertIn("Install Backend and install audio.cpp.", text)
+        self.assertIn("qwen3_tts_1_7b_base_q8_0", text)
+        self.assertIn("qwen3_tts_1_7b_customvoice_q8_0", text)
+        self.assertIn("5. Go to Generate Audiobooks.", text)
+        self.assertIn("6. Generated audiobooks (m4b, mp3, etc.) will "
+                      "output here:", text)
+        self.assertIn(str(hub.AUDIOBOOKS_FOLDER), text)
+
 
 class SubmenuStatusTableTests(unittest.TestCase):
     """First picker screen of every flow repeats the backend status table.
@@ -375,7 +416,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
         self.assertEqual([label for label, _ in captured["options"]],
                          ["Install Backend", "Uninstall Backend"])
         # ...the shared status table carries the states instead.
-        self.assertEqual(captured["table_title"], "Backend status")
+        self.assertEqual(captured["table_title"], "Backend Status")
         self.assertEqual(
             captured["table_rows"],
             [("qwen-tts", "installed", "ok", "body"),
@@ -421,7 +462,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
         # the whole set of installed backends (faster has nothing on disk
         # and so contributes nothing).
         self.assertEqual([label for label, _ in captured["options"]],
-                         ["Install Backend", "Update backends",
+                         ["Install Backend", "Update Backends",
                           "Uninstall Backend"])
 
     def test_configure_backends_menu_audiocpp_model_actions(self):
@@ -492,9 +533,9 @@ class SubmenuStatusTableTests(unittest.TestCase):
         # model download stays hidden until the binary exists — Build and
         # Download never coexist. Configure needs an installed (built)
         # backend.
-        self.assertEqual(labels, ["Build audio.cpp server", "Uninstall Backend"])
+        self.assertEqual(labels, ["Build audio.cpp Server", "Uninstall Backend"])
         self.assertEqual(captured["options"][0],
-                         ("Build audio.cpp server", "build_audiocpp",
+                         ("Build audio.cpp Server", "build_audiocpp",
                           ("[recommended]", "warn")))
         self.assertIs(captured["options"][1], tui.MENU_SEPARATOR)
 
@@ -520,7 +561,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
                 result = hub._Hub(None).screen_configure()
         self.assertIs(result, tui.Wizard.BACK)
         labels = self._labels(captured["options"])
-        self.assertNotIn("Build audio.cpp server", labels)
+        self.assertNotIn("Build audio.cpp Server", labels)
 
     def test_configure_backends_menu_configure_only_when_built_unconfigured(self):
         captured = {}
@@ -607,7 +648,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
 
     def test_bare_qwen_without_configure_screen_still_has_no_entry(self):
         # Without a dedicated configure screen, plain qwen stays excluded
-        # from Configure backends (its wizard asks nothing to configure).
+        # from Configure Backends (its wizard asks nothing to configure).
         captured = {}
         infos = [BackendInfo("qwen", "qwen-tts", lambda: None, lambda: 0,
                              uninstall=lambda **kwargs: 0)]
@@ -633,7 +674,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
                 patch.object(hub.shutil, "which", return_value="/x"):
             result = hub._Hub(None).screen_convert()
         self.assertIs(result, tui.Wizard.BACK)
-        self.assertEqual(captured["title"], "Generate audiobooks")
+        self.assertEqual(captured["title"], "Generate Audiobooks")
         # One form, no picker menu: the first field is the Backend picker,
         # and only convertible backends are offered in it.
         self.assertEqual(captured["fields"][0]["key"], "backend")
@@ -677,7 +718,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
                 patch.object(hub.shutil, "which", return_value="/x"):
             result = hub._Hub(None).screen_configure()
         self.assertIs(result, tui.Wizard.BACK)
-        self.assertEqual(captured["table_title"], "Backend status")
+        self.assertEqual(captured["table_title"], "Backend Status")
         self.assertEqual(
             captured["table_rows"], [("qwen-tts", "installed", "ok",
                                       "body")])
@@ -706,7 +747,7 @@ class SubmenuStatusTableTests(unittest.TestCase):
                          ["audio.cpp"])
         # The running/stopped state lives in the status table above the
         # menu (not on the entries, whose colors the selection bar covers).
-        self.assertEqual(captured["table_title"], "Server status")
+        self.assertEqual(captured["table_title"], "Server Status")
         self.assertEqual(captured["table_rows"],
                          [("audio.cpp", "stopped", "err", "body")])
 
@@ -863,7 +904,7 @@ class ConvertFlowTests(unittest.TestCase):
         # One form, not a cascade of menus/editors.
         self.assertEqual(len(self.tui.forms_seen), 1)
         title, fields, form_kwargs = self.tui.forms_seen[0]
-        self.assertEqual(title, "Generate audiobooks")
+        self.assertEqual(title, "Generate Audiobooks")
         self.assertEqual([f["key"] for f in fields],
                          ["backend", "audiocpp-remote.model_id",
                           "audiocpp-remote.audiocpp_voice",
@@ -991,7 +1032,7 @@ class ConvertFlowTests(unittest.TestCase):
     def test_audiocpp_local_without_voice_dir_points_at_configure(self):
         # The managed entry's server.json has no voice_dir: clone-capable
         # models get an empty Voice picker whose hint sends the user to
-        # Configure backends instead of crashing on menu().
+        # Configure Backends instead of crashing on menu().
         with tempfile.TemporaryDirectory() as td:
             root = Path(td)
             (root / "server.json").write_text(json.dumps({
@@ -1012,7 +1053,7 @@ class ConvertFlowTests(unittest.TestCase):
         error = voice_field["validate"]("")
         self.assertIsNotNone(error)
         self.assertIn(".wav", error)
-        self.assertIn("Configure backends", error)
+        self.assertIn("Configure Backends", error)
 
     def test_audiocpp_remote_missing_family_is_clone_capable(self):
         # A missing family is unknown — not guessed as qwen3_tts — so the
@@ -2213,7 +2254,7 @@ class SettingsTests(unittest.TestCase):
         self.assertIsNotNone(hub._validate_port("abc"))
 
     def test_language_fields_are_pickers_with_edit_hint(self):
-        # Both Language fields (Settings and Generate audiobooks) are
+        # Both Language fields (Settings and Generate Audiobooks) are
         # static pickers over the audio.cpp-menu languages, with a dim
         # hint inside their edit dialog. Common languages lead.
         expected_choices = ["English", "Spanish", "Chinese", "French",
@@ -2820,12 +2861,12 @@ class ConfigureBackendsDispatchTests(unittest.TestCase):
                              return_value=0) as mk_run, \
                 patch_flash:
             hub._update_backends_action(None)
-            # One task-view run titled "Update backends", one step per
+            # One task-view run titled "Update Backends", one step per
             # updatable backend in registry order; executing a step
             # forwards emit/cancel to that backend's update.
             mk_run.assert_called_once()
             self.assertEqual(mk_run.call_args[0][0], None)
-            self.assertEqual(mk_run.call_args[0][1], "Update backends")
+            self.assertEqual(mk_run.call_args[0][1], "Update Backends")
             steps = mk_run.call_args[0][2]
             self.assertEqual([step.title for step in steps],
                              ["Update audio.cpp", "Update qwen-tts"])
@@ -2908,7 +2949,7 @@ class ConfigureBackendsDispatchTests(unittest.TestCase):
         self.assertEqual(invalidated, [True])
         # An inline action: the same menu re-shows (second title) with a
         # freshly detected status table.
-        self.assertEqual(titles, ["Configure backends", "Configure backends"])
+        self.assertEqual(titles, ["Configure Backends", "Configure Backends"])
 
     def test_pick_backend_install_lists_uninstalled_only(self):
         captured = {}
@@ -3067,7 +3108,7 @@ class HubNavigationTests(unittest.TestCase):
     def test_esc_on_wizard_first_screen_returns_to_configure(self):
         # The reported bug: Esc on the audio.cpp "Select TTS model
         # families" tree (the wizard's first screen) must land back on
-        # "Configure backends", not the main menu.
+        # "Configure Backends", not the main menu.
         info = self._info()
         with patch.object(info, "setup_screen", return_value=1):
             titles = self._drive(
@@ -3076,8 +3117,8 @@ class HubNavigationTests(unittest.TestCase):
                 [self._status()], [info])
         self.assertEqual(
             titles,
-            ["tts-audiobook-generator", "Configure backends",
-             "Configure backends", "tts-audiobook-generator"])
+            ["tts-audiobook-generator", "Configure Backends",
+             "Configure Backends", "tts-audiobook-generator"])
 
     def test_esc_on_install_picker_returns_to_configure(self):
         registry = [self._info("audiocpp", "audio.cpp"),
@@ -3091,8 +3132,8 @@ class HubNavigationTests(unittest.TestCase):
             statuses, registry)
         self.assertEqual(
             titles,
-            ["tts-audiobook-generator", "Configure backends",
-             "Install Backend", "Configure backends",
+            ["tts-audiobook-generator", "Configure Backends",
+             "Install Backend", "Configure Backends",
              "tts-audiobook-generator"])
 
     def test_esc_on_server_action_returns_one_screen_at_a_time(self):
@@ -3122,8 +3163,8 @@ class HubNavigationTests(unittest.TestCase):
         # Esc steps back one screen at a time to the server list and main.
         self.assertEqual(
             titles,
-            ["tts-audiobook-generator", "Start / Stop a server",
-             "Start / Stop a server", "tts-audiobook-generator"])
+            ["tts-audiobook-generator", "Start / Stop A Server",
+             "Start / Stop A Server", "tts-audiobook-generator"])
 
     def test_esc_on_main_menu_quits(self):
         titles = self._drive([tui.Wizard.BACK], [], [])
diff --git a/app/tests/test_tui.py b/app/tests/test_tui.py
index eb6872a..916f434 100644
--- a/app/tests/test_tui.py
+++ b/app/tests/test_tui.py
@@ -267,7 +267,7 @@ class MenuTests(TuiTestCase):
     def test_suffix_renders_in_its_theme_color(self):
         # default_index=1 keeps the suffixed option unselected, so its
         # segments keep their own colors instead of the cursor bar.
-        options = [("Build audio.cpp server", "build",
+        options = [("Build audio.cpp Server", "build",
                     ("[recommended]", "warn")), ("other", "other")]
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Pick", options, default_index=1)
@@ -276,7 +276,7 @@ class MenuTests(TuiTestCase):
                     if drawn == text)
         self.assertEqual(attr, tui._THEME["warn"])
         label_attr = next(a for _, _, drawn, a in screen.strings
-                          if drawn == "Build audio.cpp server")
+                          if drawn == "Build audio.cpp Server")
         self.assertEqual(label_attr, tui._THEME["body"])
 
     def test_selected_row_has_arrow_in_the_margin(self):
@@ -317,7 +317,7 @@ class MenuTableTests(TuiTestCase):
     def test_name_column_left_aligned_at_margin(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS)
+                 table_title="Backend Status", table_rows=self.ROWS)
         x0, _ = self.dialog_box(screen)
         margin = x0 + 1 + tui.Frame.LIST_MARGIN
         for name, _, _ in self.ROWS:
@@ -328,7 +328,7 @@ class MenuTableTests(TuiTestCase):
     def test_status_column_aligned_at_one_fixed_offset(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS)
+                 table_title="Backend Status", table_rows=self.ROWS)
         x0, _ = self.dialog_box(screen)
         margin = x0 + 1 + tui.Frame.LIST_MARGIN
         name_w = max(len(name) for name, _, _ in self.ROWS)
@@ -341,7 +341,7 @@ class MenuTableTests(TuiTestCase):
     def test_status_text_uses_the_theme_kind_color(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS)
+                 table_title="Backend Status", table_rows=self.ROWS)
         want = {"err": tui._THEME["err"], "warn": tui._THEME["warn"],
                 "ok": tui._THEME["ok"]}
         for _, status, kind in self.ROWS:
@@ -362,7 +362,7 @@ class MenuTableTests(TuiTestCase):
     def test_three_element_rows_default_to_body_names(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS)
+                 table_title="Backend Status", table_rows=self.ROWS)
         for name, _, _ in self.ROWS:
             attr = next(a for _, _, text, a in screen.strings
                         if text.rstrip() == name)
@@ -371,24 +371,24 @@ class MenuTableTests(TuiTestCase):
     def test_table_title_is_dim_and_left_aligned(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS)
+                 table_title="Backend Status", table_rows=self.ROWS)
         x0, _ = self.dialog_box(screen)
         margin = x0 + 1 + tui.Frame.LIST_MARGIN
         x, attr = next((x, a) for _, x, text, a in screen.strings
-                       if text == "Backend status")
+                       if text == "Backend Status")
         self.assertEqual(x, margin)
         self.assertEqual(attr, tui._THEME["dim"])
 
     def test_table_does_not_paint_over_the_border(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS)
+                 table_title="Backend Status", table_rows=self.ROWS)
         self.assert_inside_border(screen)
 
     def test_notice_line_is_red_and_above_the_table(self):
         screen = FakeScreen(keys=[10])
         tui.menu(screen, "Hub", [("Quit", "quit")],
-                 table_title="Backend status", table_rows=self.ROWS,
+                 table_title="Backend Status", table_rows=self.ROWS,
                  notice_lines=[("Warning: ffmpeg not installed!", "err")])
         x0, _ = self.dialog_box(screen)
         margin = x0 + 1 + tui.Frame.LIST_MARGIN
@@ -396,11 +396,11 @@ class MenuTableTests(TuiTestCase):
                        if text == "Warning: ffmpeg not installed!")
         self.assertEqual(x, margin)
         self.assertEqual(attr, tui._THEME["err"])
-        # The notice sits above the table title ("Backend status").
+        # The notice sits above the table title ("Backend Status").
         notice_y = next(y for y, _, text, _ in screen.strings
                         if text == "Warning: ffmpeg not installed!")
         title_y = next(y for y, _, text, _ in screen.strings
-                       if text == "Backend status")
+                       if text == "Backend Status")
         self.assertLess(notice_y, title_y)
         self.assert_inside_border(screen)
 
@@ -1283,6 +1283,88 @@ class FlashTests(TuiTestCase):
         self.assertIsNone(frame.status)
 
 
+class TextViewerTests(TuiTestCase):
+    """tui.text_viewer: a scrollable read-only dialog; Esc/q/Enter closes."""
+
+    LINES = ["first line", "second line", "third line"]
+
+    def test_lines_render_and_enter_closes(self):
+        marker = object()
+        screen = FakeScreen(keys=[10])
+        self.assertIs(
+            tui.text_viewer(screen, "Help", self.LINES, back_value=marker),
+            marker)
+        for line in self.LINES:
+            self.assertTrue(any(text == line for _, _, text, _
+                                in screen.strings), line)
+        self.assert_inside_border(screen)
+
+    def test_esc_returns_back_value(self):
+        marker = object()
+        screen = FakeScreen(keys=[27])
+        self.assertIs(
+            tui.text_viewer(screen, "Help", self.LINES, back_value=marker),
+            marker)
+
+    def test_q_returns_back_value_like_esc(self):
+        marker = object()
+        screen = FakeScreen(keys=[ord("q")])
+        self.assertIs(
+            tui.text_viewer(screen, "Help", self.LINES, back_value=marker),
+            marker)
+
+    def test_esc_aborts_without_back_value(self):
+        screen = FakeScreen(keys=[27])
+        with self.assertRaises(tui.WizardCancelled):
+            tui.text_viewer(screen, "Help", self.LINES)
+
+    def test_enter_aborts_without_back_value(self):
+        screen = FakeScreen(keys=[10])
+        with self.assertRaises(tui.WizardCancelled):
+            tui.text_viewer(screen, "Help", self.LINES)
+
+    def test_no_cursor_bar_is_drawn(self):
+        # Read-only: no row is selectable, so even with the cursor on a
+        # line the cyan selection bar never paints.
+        screen = FakeScreen(keys=[FakeCurses.KEY_END, ord("q")])
+        tui.text_viewer(screen, "Help", self.LINES, back_value=object())
+        bars = [s for s in screen.strings
+                if s[3] == tui._THEME["bar"] and not s[2].strip()]
+        self.assertEqual(bars, [])
+
+    def test_end_scrolls_the_last_line_into_view(self):
+        # Content taller than the terminal: End shows the last line and
+        # the frame's scroll indicator appears in the border.
+        lines = [f"line {i}" for i in range(40)]
+        screen = FakeScreen(keys=[FakeCurses.KEY_END, ord("q")])
+        tui.text_viewer(screen, "Help", lines, back_value=object())
+        drawn = [text for _, _, text, _ in screen.strings]
+        self.assertIn("line 39", drawn)
+        self.assertTrue(any("/40" in text for text in drawn))
+
+    def test_home_returns_to_the_top(self):
+        lines = [f"line {i}" for i in range(40)]
+        screen = FakeScreen(keys=[FakeCurses.KEY_END, FakeCurses.KEY_HOME,
+                                  ord("q")])
+        tui.text_viewer(screen, "Help", lines, back_value=object())
+        drawn = [text for _, _, text, _ in screen.strings]
+        self.assertIn("line 0", drawn)
+
+    def test_page_down_moves_a_full_page(self):
+        # PageDown from the top lands one page (17 visible rows) down:
+        # the first line scrolls off, the next one is at the top.
+        lines = [f"line {i}" for i in range(40)]
+        screen = FakeScreen(keys=[FakeCurses.KEY_NPAGE, ord("q")])
+        tui.text_viewer(screen, "Help", lines, back_value=object())
+        # Only the final frame counts: strings accumulate across redraws.
+        titles = [i for i, entry in enumerate(screen.strings)
+                  if entry[2] == " Help "]
+        drawn = [entry[2] for entry in screen.strings[titles[-1]:]]
+        self.assertIn("line 1", drawn)
+        self.assertNotIn("line 0", drawn)
+        self.assertIn(" 2/40 ", drawn)
+
+
 class WizardTests(unittest.TestCase):
     """The tui.Wizard screen-stack driver: Esc steps back one screen."""