fix(lexer): Include underscores in lowercase metavar patterns

Lowercase metavars like `socket_name` were split at underscores because
the regex `[a-z][-a-z0-9]*` didn't include `_`. Changed to `[a-z][-a-z0-9_]*`
in all 6 pattern locations.

Fixes: tmuxp load usage showing `<span>socket</span>_name` instead of
`<span>socket_name</span>`.

Author: tony

docs/_ext/argparse_lexer.py

@@ -56,7 +56,7 @@ class ArgparseUsageLexer(RegexLexer):
             # Whitespace
             (r"\s+", Whitespace),
             # Program name (first lowercase word after usage:)
-            (r"\b[a-z][-a-z0-9]*\b", Name.Label, "usage_body"),
+            (r"\b[a-z][-a-z0-9_]*\b", Name.Label, "usage_body"),
             # Fallback to inline if something unexpected
             include("inline"),
         ],
@@ -67,14 +67,14 @@ class ArgparseUsageLexer(RegexLexer):
             (r"\.\.\.", Punctuation),
             # Long options with = value (e.g., --log-level=VALUE)
             (
-                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Tag, Operator, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Long options standalone
             (r"--[a-zA-Z0-9][-a-zA-Z0-9]*", Name.Tag),
             # Short options with space-separated value (e.g., -S socket-path)
             (
-                r"(-[a-zA-Z0-9])(\s+)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(-[a-zA-Z0-9])(\s+)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Attribute, Whitespace, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Short options standalone
@@ -94,7 +94,7 @@ class ArgparseUsageLexer(RegexLexer):
             # UPPERCASE meta-variables (COMMAND, FILE, PATH)
             (r"\b[A-Z][A-Z0-9_]*\b", Name.Variable),
             # Subcommand/positional names (Name.Function for distinct styling)
-            (r"\b[a-z][-a-z0-9]*\b", Name.Function),
+            (r"\b[a-z][-a-z0-9_]*\b", Name.Function),
             # Catch-all for any other text
             (r"[^\s\[\]|(){},]+", Text),
         ],
@@ -105,14 +105,14 @@ class ArgparseUsageLexer(RegexLexer):
             (r"\.\.\.", Punctuation),
             # Long options with = value (e.g., --log-level=VALUE)
             (
-                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Tag, Operator, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Long options standalone
             (r"--[a-zA-Z0-9][-a-zA-Z0-9]*", Name.Tag),
             # Short options with space-separated value (e.g., -S socket-path)
             (
-                r"(-[a-zA-Z0-9])(\s+)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(-[a-zA-Z0-9])(\s+)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Attribute, Whitespace, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Short options standalone
@@ -132,7 +132,7 @@ class ArgparseUsageLexer(RegexLexer):
             # UPPERCASE meta-variables (COMMAND, FILE, PATH)
             (r"\b[A-Z][A-Z0-9_]*\b", Name.Variable),
             # Positional/command names (lowercase with dashes)
-            (r"\b[a-z][-a-z0-9]*\b", Name.Label),
+            (r"\b[a-z][-a-z0-9_]*\b", Name.Label),
             # Catch-all for any other text
             (r"[^\s\[\]|(){},]+", Text),
         ],
@@ -214,7 +214,7 @@ class ArgparseHelpLexer(RegexLexer):
             # Whitespace
             (r"\s+", Whitespace),
             # Program name (first lowercase word after usage:)
-            (r"\b[a-z][-a-z0-9]*\b", Name.Label, "usage"),
+            (r"\b[a-z][-a-z0-9_]*\b", Name.Label, "usage"),
             # Fallback to usage if something unexpected
             include("usage_inline"),
         ],
@@ -234,14 +234,14 @@ class ArgparseHelpLexer(RegexLexer):
             (r"\.\.\.", Punctuation),
             # Long options with = value
             (
-                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Tag, Operator, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Long options standalone
             (r"--[a-zA-Z0-9][-a-zA-Z0-9]*", Name.Tag),
             # Short options with value
             (
-                r"(-[a-zA-Z0-9])(\s+)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(-[a-zA-Z0-9])(\s+)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Attribute, Whitespace, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Short options standalone
@@ -259,7 +259,7 @@ class ArgparseHelpLexer(RegexLexer):
             # UPPERCASE metavars
             (r"\b[A-Z][A-Z0-9_]*\b", Name.Variable),
             # Subcommand/positional names (Name.Function for distinct styling)
-            (r"\b[a-z][-a-z0-9]*\b", Name.Function),
+            (r"\b[a-z][-a-z0-9_]*\b", Name.Function),
             # Other text
             (r"[^\s\[\]|(){},\n]+", Text),
         ],
@@ -271,7 +271,7 @@ class ArgparseHelpLexer(RegexLexer):
             ),
             # Long options with = value
             (
-                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9]*)",
+                r"(--[a-zA-Z0-9][-a-zA-Z0-9]*)(=)([A-Z][A-Z0-9_]*|[a-z][-a-z0-9_]*)",
                 bygroups(Name.Tag, Operator, Name.Variable),  # type: ignore[no-untyped-call]
             ),
             # Long options with space-separated metavar

tests/docs/_ext/test_argparse_lexer.py

@@ -477,6 +477,18 @@ class ShortOptionValueFixture(t.NamedTuple):
         option="-r",
         value="name",
     ),
+    ShortOptionValueFixture(
+        test_id="underscore_metavar",
+        input_text="-L socket_name",
+        option="-L",
+        value="socket_name",
+    ),
+    ShortOptionValueFixture(
+        test_id="multiple_underscores",
+        input_text="-f tmux_config_file",
+        option="-f",
+        value="tmux_config_file",
+    ),
 ]
 
 
@@ -796,3 +808,18 @@ def test_argparse_help_lexer_multiline() -> None:
     assert "options:" in token_values or any(
         "options:" in v for v in token_values if isinstance(v, str)
     )
+
+
+def test_tmuxp_load_usage_underscores() -> None:
+    """Test tmuxp load usage with underscore metavars.
+
+    Regression test for underscore handling in lowercase metavars.
+    Previously, `socket_name` was tokenized as `socket` + `_name` (split).
+    """
+    usage = "usage: tmuxp load [-L socket_name] [-S socket_path] [-f tmux_config_file]"
+    tokens = get_usage_tokens(usage)
+
+    # All underscore metavars should be fully captured
+    assert ("Token.Name.Variable", "socket_name") in tokens
+    assert ("Token.Name.Variable", "socket_path") in tokens
+    assert ("Token.Name.Variable", "tmux_config_file") in tokens