diff --git a/src/bmad_loop/tui/data.py b/src/bmad_loop/tui/data.py
index b0beadd..b66c415 100644
--- a/src/bmad_loop/tui/data.py
+++ b/src/bmad_loop/tui/data.py
@@ -22,6 +22,7 @@
 from typing import Any
 
 import pyte
+from rich.color import ColorParseError
 from rich.style import Style
 from rich.text import Text
 
@@ -269,8 +270,16 @@ def read_new(self) -> list[dict[str, Any]]:
 _PANE_LINES = 50
 _HISTORY_LINES = 2000  # matches the dashboard RichLog max_lines
 
-# pyte names SGR 33 "brown"; aixterm brights carry no underscore.
-_PYTE_COLOR_FIX = {"brown": "yellow", "brightbrown": "bright_yellow"}
+# pyte names SGR 33 "brown"; aixterm brights carry no underscore. Values here
+# must stay in pyte's own (underscore-free) namespace: _rich_color re-applies
+# the "bright" -> "bright_" transform after this remap, so a "bright_"-prefixed
+# value would double up into "bright__yellow" (an invalid rich color).
+# "bfightmagenta" is pyte 0.8.2's own BG_AIXTERM[105] typo (SGR 105).
+_PYTE_COLOR_FIX = {
+    "brown": "yellow",
+    "brightbrown": "brightyellow",
+    "bfightmagenta": "brightmagenta",
+}
 _HEX_DIGITS = set("0123456789abcdef")
 
 
@@ -294,15 +303,21 @@ def _char_style(key: tuple) -> Style:
     style = _style_cache.get(key)
     if style is None:
         fg, bg, bold, italics, underscore, strikethrough, reverse = key
-        style = _style_cache[key] = Style(
-            color=_rich_color(fg),
-            bgcolor=_rich_color(bg),
+        attrs = dict(
             bold=bold or None,
             italic=italics or None,
             underline=underscore or None,
             strike=strikethrough or None,
             reverse=reverse or None,
         )
+        try:
+            style = Style(color=_rich_color(fg), bgcolor=_rich_color(bg), **attrs)
+        except ColorParseError:
+            # A color name rich can't parse (e.g. a new pyte table entry) must
+            # degrade to an uncolored run, not kill the poll worker — and with
+            # it the app (textual workers default to exit_on_error=True).
+            style = Style(**attrs)
+        _style_cache[key] = style
     return style
 
 
diff --git a/tests/test_tui_data.py b/tests/test_tui_data.py
index 35e8444..c92f994 100644
--- a/tests/test_tui_data.py
+++ b/tests/test_tui_data.py
@@ -888,3 +888,55 @@ def test_run_watcher_state_refreshes_on_same_size_rewrite(tmp_path):
     assert after.st_size == pinned.st_size and after.st_mtime_ns == pinned.st_mtime_ns
 
     assert watcher.state() is not first  # re-parsed because the inode changed
+
+
+def test_rich_color_maps_pyte_names_to_valid_rich_colors():
+    # pyte emits aixterm bright names without an underscore (e.g. "brightbrown"
+    # for SGR 93). _rich_color remaps pyte's "brown"/"brightbrown" and then
+    # applies the "bright" -> "bright_" transform; the remap target must stay in
+    # pyte's underscore-free namespace or the transform doubles the underscore
+    # into an invalid "bright__yellow" and every log render raises ColorParseError.
+    from rich.color import Color
+
+    cases = {
+        "default": None,
+        "brown": "yellow",
+        "brightbrown": "bright_yellow",  # regression: was "bright__yellow"
+        "bfightmagenta": "bright_magenta",  # pyte 0.8.2 BG_AIXTERM[105] typo
+        "red": "red",
+        "brightred": "bright_red",
+        "brightyellow": "bright_yellow",
+        "ff00aa": "#ff00aa",
+    }
+    for pyte_name, expected in cases.items():
+        got = data._rich_color(pyte_name)
+        assert got == expected, f"{pyte_name!r} -> {got!r}, expected {expected!r}"
+        if got is not None:
+            Color.parse(got)  # must be a color rich accepts, else the TUI crashes
+
+    # Exhaustive: every name the installed pyte can emit must map to something
+    # rich parses — a pyte bump that adds/renames table entries fails here, not
+    # in the dashboard's poll worker.
+    import pyte.graphics as graphics
+
+    every_pyte_name = (
+        set(graphics.FG.values())
+        | set(graphics.BG.values())
+        | set(graphics.FG_AIXTERM.values())
+        | set(graphics.BG_AIXTERM.values())
+    )
+    for pyte_name in sorted(every_pyte_name):
+        got = data._rich_color(pyte_name)
+        if got is not None:
+            Color.parse(got)
+
+
+def test_char_style_degrades_unparseable_color_instead_of_raising():
+    # Belt to the sweep test's suspenders: if a color name rich can't parse
+    # ever slips through _rich_color, the run renders uncolored instead of
+    # killing the poll worker (and, via exit_on_error, the whole app).
+    key = ("no_such_color", "default", True, False, True, False, False)
+    style = data._char_style(key)
+    assert style.color is None and style.bgcolor is None
+    assert style.bold and style.underline and not style.italic
+    assert data._char_style(key) is style  # fallback is cached like any other