Feat/improve offense output message

CHANGELOG.md

@@ -1,5 +1,18 @@
 # Changelog
 
+## [1.2.0] - 2026-03-11
+
+### Changed
+
+- Default `--format file` output now shows human-readable explanation with config key in brackets:
+  `L73  Hash#fetch with second argument is slower than Hash#fetch with block [fetch_with_argument_vs_block]`
+- Performance: use `HashSet` instead of `Vec` for file exclusion lookup (O(1) vs O(n))
+
+### Internal
+
+- Test coverage increased from 61.87% to 93.10% (242 tests)
+- Upgrade GitHub Actions to Node.js 24 compatible versions (checkout@v6, upload-artifact@v7, download-artifact@v8)
+
 ## [1.1.1] - 2026-03-11
 
 ### Changed

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rubyfast"
-version = "1.1.1"
+version = "1.2.0"
 edition = "2021"
 description = "A Ruby performance linter rewritten in Rust — detects 19 common anti-patterns, ~100x faster than the original fasterer gem"
 license = "MIT"

README.md

@@ -46,11 +46,11 @@ Groups offenses by file path — compact and easy to scan:
 
 ```
 app/controllers/concerns/lottery_common.rb
-  L13  fetch_with_argument_vs_block
-  L94  fetch_with_argument_vs_block
+  L13  Hash#fetch with second argument is slower than Hash#fetch with block [fetch_with_argument_vs_block]
+  L94  Hash#fetch with second argument is slower than Hash#fetch with block [fetch_with_argument_vs_block]
 
 app/controllers/api/v1/health_articles_controller.rb
-  L11  fetch_with_argument_vs_block
+  L11  Hash#fetch with second argument is slower than Hash#fetch with block [fetch_with_argument_vs_block]
 ```
 
 ### `--format rule`

src/output.rs

@@ -26,8 +26,8 @@ pub fn print_results(result: &TraversalResult, format: &OutputFormat) {
 ///
 /// ```text
 /// app/controllers/concerns/lottery_common.rb
-///   L13  fetch_with_argument_vs_block
-///   L94  fetch_with_argument_vs_block
+///   L13  Hash#fetch with second argument is slower than Hash#fetch with block [fetch_with_argument_vs_block]
+///   L94  Hash#fetch with second argument is slower than Hash#fetch with block [fetch_with_argument_vs_block]
 /// ```
 fn print_results_by_file(result: &TraversalResult) {
     for analysis in &result.results {
@@ -37,9 +37,10 @@ fn print_results_by_file(result: &TraversalResult) {
         println!("{}", analysis.path.bold());
         for offense in &analysis.offenses {
             println!(
-                "  {}  {}",
+                "  {}  {} [{}]",
                 format!("L{}", offense.line).cyan(),
-                offense.kind.config_key()
+                offense.kind.explanation(),
+                offense.kind.config_key().dimmed()
             );
         }
         println!();