Preserve CLI option dashes from smart dash conversion

Protect --option and ---option patterns (whitespace-preceded dashes
followed by word characters) using the existing placeholder mechanism.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jdmonaco

mdformat_space_control/__init__.py

@@ -1,6 +1,6 @@
 """An mdformat plugin for space control: EditorConfig indentation, tight lists, frontmatter spacing, smart dash conversion, soft break joining, and wikilinks."""
 
-__version__ = "0.4.2"
+__version__ = "0.4.3"
 
 from .config import (
     get_current_file,

mdformat_space_control/plugin.py

@@ -411,6 +411,9 @@ def _convert_dash_sequences(text: str) -> str:
     em_dash_re = re.compile(r"(?<!-)---(?!-)")
     en_dash_re = re.compile(r"(?<!-)--(?!-)")
 
+    # CLI option pattern: --word or ---word preceded by whitespace or line start
+    cli_option_re = re.compile(r"(?<=\s)-{2,3}(?=\w)")
+
     # Lines that are only dashes (thematic breaks, frontmatter delimiters)
     only_dashes_re = re.compile(r"^-{2,}\s*$")
 
@@ -453,6 +456,9 @@ def _save_placeholder(m: re.Match) -> str:
             protected = html_comment_re.sub(_save_placeholder, protected)
             protected = html_tag_re.sub(_save_placeholder, protected)
 
+            # Protect CLI option dashes (e.g., --output, ---long-opt)
+            protected = cli_option_re.sub(_save_placeholder, protected)
+
             # Convert em-dash first (longer match), then en-dash
             protected = em_dash_re.sub("\u2014", protected)
             protected = en_dash_re.sub("\u2013", protected)