fix(tui): remove double space after numbered-list marker

The ordered-list branch in _apply_markdown_styles emitted its own
"N. " prefix and then re-rendered the remainder from line[2:], which
still includes the marker's trailing space (a numbered marker like
"1. " is 3 chars). The result was a doubled space, e.g. "1.  Hello".
Slice from line[3:] to skip the whole marker, matching the 2-char
bullet branch that already uses line[2:]. Add regression tests.

Closes #684

strix/interface/tui/renderers/agent_message_renderer.py

@@ -104,7 +104,7 @@ def _apply_markdown_styles(text: str) -> Text:  # noqa: PLR0912
             result.append_text(_process_inline_formatting(line[2:]))
         elif len(line) > 2 and line[0].isdigit() and line[1:3] in (". ", ") "):
             result.append(line[0] + ". ", style="#22c55e")
-            result.append_text(_process_inline_formatting(line[2:]))
+            result.append_text(_process_inline_formatting(line[3:]))
         elif line.strip() in ("---", "***", "___"):
             result.append("─" * 40, style="#22c55e")
         else:

tests/test_agent_message_renderer.py

@@ -0,0 +1,23 @@
+"""Tests for markdown styling in the agent-message TUI renderer."""
+
+from __future__ import annotations
+
+from strix.interface.tui.renderers.agent_message_renderer import _apply_markdown_styles
+
+
+def test_numbered_list_has_single_space_after_marker() -> None:
+    result = _apply_markdown_styles("1. Hello").plain
+
+    assert result == "1. Hello"
+    assert "1.  Hello" not in result
+
+
+def test_numbered_list_paren_marker_normalized_single_space() -> None:
+    result = _apply_markdown_styles("2) World").plain
+
+    assert result == "2. World"
+    assert "2.  World" not in result
+
+
+def test_bullet_list_marker_unaffected() -> None:
+    assert _apply_markdown_styles("- Item").plain == "• Item"