fix(message): use unicode char count for text width

src/commit/types/commit_type.rs

@@ -61,6 +61,15 @@ impl CommitType {
             Self::Revert => "revert",
         }
     }
+
+    /// Returns the length in characters
+    ///
+    /// `is_empty()` is intentionally absent: `CommitType` is
+    /// guaranteed non-empty, so the concept does not apply.
+    #[allow(clippy::len_without_is_empty)]
+    pub fn len(&self) -> usize {
+        self.as_str().chars().count()
+    }
 }
 
 impl std::fmt::Display for CommitType {
@@ -274,4 +283,33 @@ mod tests {
         let debug_output = format!("{:?}", CommitType::Feat);
         assert!(debug_output.contains("Feat"));
     }
+
+    /// Test len() returns the correct character count for each variant
+    #[test]
+    fn len_returns_correct_character_count() {
+        assert_eq!(CommitType::Feat.len(), 4);
+        assert_eq!(CommitType::Fix.len(), 3);
+        assert_eq!(CommitType::Docs.len(), 4);
+        assert_eq!(CommitType::Style.len(), 5);
+        assert_eq!(CommitType::Refactor.len(), 8);
+        assert_eq!(CommitType::Perf.len(), 4);
+        assert_eq!(CommitType::Test.len(), 4);
+        assert_eq!(CommitType::Build.len(), 5);
+        assert_eq!(CommitType::Ci.len(), 2);
+        assert_eq!(CommitType::Chore.len(), 5);
+        assert_eq!(CommitType::Revert.len(), 6);
+    }
+
+    /// Test len() agrees with as_str().chars().count() for all variants
+    #[test]
+    fn len_equals_chars_count_for_all_variants() {
+        for commit_type in CommitType::all() {
+            assert_eq!(
+                commit_type.len(),
+                commit_type.as_str().chars().count(),
+                "len() should equal chars().count() for {:?}",
+                commit_type
+            );
+        }
+    }
 }

src/commit/types/description.rs

@@ -39,7 +39,7 @@ impl Description {
     /// non-empty by its constructor, so the concept does not apply.
     #[allow(clippy::len_without_is_empty)]
     pub fn len(&self) -> usize {
-        self.0.len()
+        self.0.chars().count()
     }
 }
 
@@ -226,13 +226,28 @@ mod tests {
         assert_eq!(desc.as_str(), "my description");
     }
 
-    /// Test len() returns correct length
+    /// Test len() returns correct length for ASCII input
     #[test]
     fn len_returns_correct_length() {
         let desc = Description::parse("hello").unwrap();
         assert_eq!(desc.len(), 5);
     }
 
+    /// Test len() counts Unicode scalar values, not bytes
+    ///
+    /// Multi-byte characters (accented letters, CJK, emoji) must count as one
+    /// character each so that the 72-char first-line limit is applied correctly.
+    #[test]
+    fn len_counts_unicode_chars_not_bytes() {
+        // "café" = 4 chars, 5 bytes (é is 2 bytes in UTF-8)
+        let desc = Description::parse("café").unwrap();
+        assert_eq!(desc.len(), 4);
+
+        // Emoji: "fix 🐛" = 5 chars, 9 bytes (🐛 is 4 bytes)
+        let desc = Description::parse("fix 🐛").unwrap();
+        assert_eq!(desc.len(), 5);
+    }
+
     /// Test Display trait implementation
     #[test]
     fn display_outputs_inner_string() {

src/commit/types/message.rs

@@ -70,13 +70,10 @@ impl ConventionalCommit {
     /// - Without scope: `len(type) + 2 + len(description)`
     ///   (the 2 accounts for colon and space: ": ")
     pub fn first_line_len(&self) -> usize {
-        if self.scope.is_empty() {
-            // type: description
-            self.commit_type.as_str().len() + 2 + self.description.len()
-        } else {
-            // type(scope): description
-            self.commit_type.as_str().len() + self.scope.as_str().len() + 4 + self.description.len()
-        }
+        self.commit_type.len()
+            + self.scope.header_segment_len()
+            + 2 // ": "
+            + self.description.len()
     }
 
     /// Format the complete commit messsage
@@ -584,10 +581,6 @@ mod tests {
         assert_eq!(commit.format(), "feat(my-scope_v2/feature): add support");
     }
 
-    // =========================================================================
-    // Line Length Validation Tests
-    // =========================================================================
-
     /// Test FIRST_LINE_MAX_LENGTH constant is 72
     #[test]
     fn first_line_max_length_constant_is_72() {

src/commit/types/scope.rs

@@ -25,8 +25,13 @@ impl Scope {
             });
         }
         match lazy_regex::regex_find!(r"[^-a-zA-Z0-9_/]", &value) {
-            Some(val) => Err(ScopeError::InvalidCharacter(val.chars().next().unwrap())),
             None => Ok(Self(value)),
+            Some(val) => val
+                .chars()
+                .next()
+                .map(ScopeError::InvalidCharacter)
+                .map(Err)
+                .unwrap_or_else(|| unreachable!("regex match is always non-empty")),
         }
     }
 
@@ -44,6 +49,20 @@ impl Scope {
     pub fn as_str(&self) -> &str {
         self.0.as_str()
     }
+
+    /// Returns itself as a formatted header segment
+    pub fn header_segment(&self) -> String {
+        if self.is_empty() {
+            "".into()
+        } else {
+            format!("({self})")
+        }
+    }
+
+    /// Returns the visible length of the header segment
+    pub fn header_segment_len(&self) -> usize {
+        self.header_segment().chars().count()
+    }
 }
 
 impl std::fmt::Display for Scope {
@@ -438,4 +457,64 @@ mod tests {
         assert!(msg.contains("31"));
         assert!(msg.contains("30"));
     }
+
+    // =========================================================================
+    // header_segment() / header_segment_len() tests
+    // =========================================================================
+
+    /// Test header_segment() returns empty string for empty scope
+    #[test]
+    fn header_segment_empty_scope_returns_empty_string() {
+        assert_eq!(Scope::empty().header_segment(), "");
+    }
+
+    /// Test header_segment() wraps a non-empty scope in parentheses
+    #[test]
+    fn header_segment_wraps_scope_in_parentheses() {
+        let scope = Scope::parse("auth").unwrap();
+        assert_eq!(scope.header_segment(), "(auth)");
+    }
+
+    /// Test header_segment() for a variety of valid scopes
+    #[test]
+    fn header_segment_various_scopes() {
+        assert_eq!(Scope::parse("cli").unwrap().header_segment(), "(cli)");
+        assert_eq!(
+            Scope::parse("user-auth").unwrap().header_segment(),
+            "(user-auth)"
+        );
+        assert_eq!(
+            Scope::parse("PROJ-123/feature").unwrap().header_segment(),
+            "(PROJ-123/feature)"
+        );
+    }
+
+    /// Test header_segment_len() is 0 for an empty scope
+    #[test]
+    fn header_segment_len_empty_scope_is_zero() {
+        assert_eq!(Scope::empty().header_segment_len(), 0);
+    }
+
+    /// Test header_segment_len() includes the two parentheses characters
+    #[test]
+    fn header_segment_len_includes_parentheses() {
+        // "(auth)" = 6 chars
+        let scope = Scope::parse("auth").unwrap();
+        assert_eq!(scope.header_segment_len(), 6);
+    }
+
+    /// Test header_segment_len() agrees with header_segment().chars().count()
+    #[test]
+    fn header_segment_len_equals_segment_chars_count() {
+        let values = ["cli", "user-auth", "PROJ-123/feature"];
+        for s in values {
+            let scope = Scope::parse(s).unwrap();
+            assert_eq!(
+                scope.header_segment_len(),
+                scope.header_segment().chars().count(),
+                "header_segment_len() should equal chars().count() for scope {:?}",
+                s
+            );
+        }
+    }
 }