fix(config): polish file pattern extension mapping

Add direct unit coverage for extract_extension_from_pattern edge cases, including empty input, no-dot patterns, dotfiles, and multi-dot filenames.

Tighten the parser to reject dotfile basenames so hidden files like .gitignore do not get treated as language extensions.

Update the translator initialization test to assert against build_effective_extension_map(), which matches the runtime code path introduced by the earlier file_patterns fix.

Document the resulting C/C++ language detection behavior change in CHANGELOG.md.

Author: wtfbbqhax

CHANGELOG.md

@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+
+- **C/C++ file pattern language detection** - When `lsp_servers[].file_patterns` include simple extensions such as `**/*.c` or `**/*.h`, mcpls now derives extension-to-language mappings from those patterns and overlays them onto the workspace extension map. This changes the default behavior for matching C/C++ files to prefer the configured LSP server language instead of falling back to built-in mappings or `plaintext`.
 
 ## [0.3.5] - 2026-03-17
 

crates/mcpls-core/src/bridge/translator.rs

@@ -2776,7 +2776,7 @@ mod tests {
             lsp_servers: vec![],
         };
 
-        let extension_map = config.workspace.build_extension_map();
+        let extension_map = config.build_effective_extension_map();
         assert_eq!(extension_map.get("nu"), Some(&"nushell".to_string()));
         assert_eq!(extension_map.get("rs"), Some(&"rust".to_string()));
 

crates/mcpls-core/src/config/mod.rs

@@ -121,6 +121,11 @@ impl WorkspaceConfig {
 /// Supports common patterns such as `**/*.rs` and `*.h`.
 /// Returns `None` for patterns without a simple trailing extension.
 fn extract_extension_from_pattern(pattern: &str) -> Option<String> {
+    let basename = pattern.rsplit('/').next().unwrap_or(pattern);
+    if basename.starts_with('.') {
+        return None;
+    }
+
     let (_, ext) = pattern.rsplit_once('.')?;
     if ext.is_empty() {
         return None;
@@ -696,6 +701,29 @@ mod tests {
         assert_eq!(map.get("unknown"), None);
     }
 
+    #[test]
+    fn test_extract_extension_from_pattern_empty_string() {
+        assert_eq!(extract_extension_from_pattern(""), None);
+    }
+
+    #[test]
+    fn test_extract_extension_from_pattern_without_dot() {
+        assert_eq!(extract_extension_from_pattern("**/*"), None);
+    }
+
+    #[test]
+    fn test_extract_extension_from_pattern_dotfile() {
+        assert_eq!(extract_extension_from_pattern(".gitignore"), None);
+    }
+
+    #[test]
+    fn test_extract_extension_from_pattern_multi_dot_extension() {
+        assert_eq!(
+            extract_extension_from_pattern("foo.tar.gz"),
+            Some("gz".to_string())
+        );
+    }
+
     #[test]
     fn test_build_effective_extension_map_overrides_with_file_patterns() {
         let config = ServerConfig {