diff --git a/tai.py b/tai.py
index 9892b3c..bee31f3 100755
--- a/tai.py
+++ b/tai.py
@@ -97,7 +97,7 @@ def _fromisoformat(text):
         return parsed.replace(tzinfo=tzinfo)
     raise ValueError("invalid datetime, use ISO like 2026-10-08T09:00")
 
-VERSION = "1.33.0"
+VERSION = "1.33.1"
 WORKER_STEPS = 12
 CREATE_SKILL_STEPS = 40
 FORK_MAX_DEPTH = 2
@@ -13255,9 +13255,12 @@ class TuiApp:
         self._need_paint = True
 
     def set_theme(self, name):
-        """Switch the global theme and redraw everything. Raises
+        """Switch the global theme and repaint every cell. Cells are diffed
+        by style key (role names), which does not change with the theme, so
+        the compositor must forget what the terminal shows. Raises
         ValueError naming the available themes when unknown."""
         tui_set_theme(name)
+        self.compositor.invalidate()
         self.dirty_paint()
         return tui_theme()
 
diff --git a/test_tai.py b/test_tai.py
index 406ae85..dbcb128 100644
--- a/test_tai.py
+++ b/test_tai.py
@@ -5861,6 +5861,22 @@ class TuiThemeTests(unittest.TestCase):
         with self.assertRaises(ValueError):
             app.set_theme("nope")
 
+    def test_set_theme_repaints_every_cell_on_the_terminal(self):
+        """Regression: after a theme switch only cells whose text changed got the
+        new colors, leaving old-theme speckles on spaces and unchanged glyphs."""
+        def screen(theme, switch_to=None):
+            tai.tui_set_theme(theme)
+            app = tai.TuiApp()
+            app.rows, app.cols = 10, 40
+            app.mount(tai.TuiText("hello  world  and  more  words", style=tai.TuiStyle(fg="role:fg", bg="role:bubble_in")))
+            vt = tai.TuiVtScreen(10, 40)
+            vt.feed(app.frame_bytes().encode("utf-8"))
+            if switch_to:
+                app.set_theme(switch_to)
+                vt.feed(app.frame_bytes().encode("utf-8"))
+            return vt.grid
+        self.assertEqual(screen("dark", "gruvbox"), screen("gruvbox"))
+
     def test_cycle_order(self):
         self.assertEqual(tai.tui_cycle_theme_name("dark"), "light")
         self.assertEqual(tai.tui_cycle_theme_name("ansi"), "dark")
@@ -6207,8 +6223,10 @@ class TuiChatTests(unittest.TestCase):
             app.offload(work, lambda value, error: done.append((value, error)))
             for _ in range(300):
                 await asyncio.sleep(0.01)
+                app._fire_timers(time.time())
                 if done:
                     await asyncio.sleep(0.2)
+                    app._fire_timers(time.time())
                     break
             app.layout()
             self.shown = app.render_text()
diff --git a/tui.md b/tui.md
index fdf8e74..0656829 100644
--- a/tui.md
+++ b/tui.md
@@ -242,8 +242,10 @@ render uncolored rather than crashing.
 
 Selection precedence: `--theme` flag, `TAI_THEME` env var, `dark`
 default; an unknown name prints the available list and exits 2.
-`App.set_theme(name)` swaps the global theme and redraws everything;
-F4 cycles registry order in the chat scene. To change a color, edit
+`App.set_theme(name)` swaps the global theme and invalidates the compositor,
+because cells are diffed by style key (role names), which a theme switch does
+not change; without the invalidation only cells whose text changed got the
+new colors and old-theme speckles stayed on spaces. F4 cycles registry order in the chat scene. To change a color, edit
 one value in `_tui_builtin_themes()` or register a custom theme.
 
 ## Chat scene (`--tui`)