feat: add breaking changes section for grouped release notes

pretty_release_notes/api.py

@@ -158,6 +158,19 @@ def with_progress_reporter(self, reporter: ProgressReporter) -> "ReleaseNotesBui
 		self._progress_reporter = reporter
 		return self
 
+	def _build_grouping_config(self) -> GroupingConfig:
+		"""Build grouping config, preserving defaults when no custom headings are set."""
+		if self._type_headings:
+			return GroupingConfig(
+				group_by_type=self._group_by_type,
+				type_headings=self._type_headings,
+				other_heading=self._other_heading,
+			)
+		return GroupingConfig(
+			group_by_type=self._group_by_type,
+			other_heading=self._other_heading,
+		)
+
 	def build(self) -> ReleaseNotesClient:
 		"""Build the client with configured options.
 
@@ -186,11 +199,7 @@ def build(self) -> ReleaseNotesClient:
 				exclude_change_labels=self._exclude_labels,
 				exclude_authors=self._exclude_authors,
 			),
-			grouping=GroupingConfig(
-				group_by_type=self._group_by_type,
-				**({} if not self._type_headings else {"type_headings": self._type_headings}),
-				other_heading=self._other_heading,
-			),
+			grouping=self._build_grouping_config(),
 			prompt_path=self._prompt_path,
 			force_use_commits=self._force_use_commits,
 		)

pretty_release_notes/core/config.py

@@ -71,6 +71,7 @@ class GroupingConfig:
 		}
 	)
 	other_heading: str = "Other Changes"
+	breaking_changes_heading: str = "Breaking Changes"
 
 	def get_heading(self, type_name: str | None) -> str:
 		"""Get the section heading for a given type."""

pretty_release_notes/models/_utils.py

@@ -1,6 +1,7 @@
 import re
 
-CONVENTIONAL_TYPE_AND_SCOPE = re.compile(r"^([a-zA-Z]{2,8})(?:\(([^)]+)\))?:")
+CONVENTIONAL_TYPE_AND_SCOPE = re.compile(r"^([a-zA-Z]{2,8})(?:\(([^)]+)\))?!?:")
+BREAKING_CHANGE_PATTERN = re.compile(r"^[a-zA-Z]{2,8}(?:\([^)]+\))?!:")
 
 
 def get_conventional_type(msg: str) -> str | None:
@@ -9,6 +10,7 @@ def get_conventional_type(msg: str) -> str | None:
 	Examples:
 	'feat(regional): Address Template for Germany & Switzerland' -> 'feat'
 	'Revert "perf: timeout while renaming cost center"' -> None
+	'fix!: breaking change' -> 'fix'
 	"""
 	if not msg:
 		return None
@@ -21,3 +23,25 @@ def get_conventional_type(msg: str) -> str | None:
 
 	match = CONVENTIONAL_TYPE_AND_SCOPE.match(msg)
 	return match.group(1).lower() if match else None
+
+
+def is_breaking_change(msg: str) -> bool:
+	"""Check if a message indicates a breaking change.
+
+	Breaking changes are indicated by an exclamation mark (!) after the type/scope
+	and before the colon, following the Conventional Commits specification.
+
+	Examples:
+	'feat!: breaking feature' -> True
+	'fix(api)!: breaking fix' -> True
+	'feat: regular feature' -> False
+	"""
+	if not msg:
+		return False
+
+	# Strip leading/trailing whitespace
+	msg = msg.strip()
+
+	# Check for the ! indicator before the colon
+	# Pattern: type(scope)!: or type!:
+	return bool(BREAKING_CHANGE_PATTERN.match(msg))

pretty_release_notes/models/commit.py

@@ -1,7 +1,7 @@
 from dataclasses import dataclass
 from typing import TYPE_CHECKING
 
-from ._utils import get_conventional_type
+from ._utils import get_conventional_type, is_breaking_change
 from .change import Change
 
 if TYPE_CHECKING:
@@ -24,6 +24,11 @@ class Commit(Change):
 	def conventional_type(self) -> str | None:
 		return get_conventional_type(self.message)
 
+	@property
+	def is_breaking(self) -> bool:
+		"""Check if this commit represents a breaking change."""
+		return is_breaking_change(self.message)
+
 	def get_prompt(self, prompt_template: str, max_patch_size: int) -> str:
 		prompt = prompt_template
 

pretty_release_notes/models/pull_request.py

@@ -3,7 +3,7 @@
 from dataclasses import dataclass
 from typing import TYPE_CHECKING
 
-from ._utils import get_conventional_type
+from ._utils import get_conventional_type, is_breaking_change
 from .change import Change
 
 if TYPE_CHECKING:
@@ -76,9 +76,21 @@ def conventional_type(self) -> str | None:
 		Examples:
 		'feat(regional): Address Template for Germany & Switzerland' -> 'feat'
 		'Revert "perf: timeout while renaming cost center"' -> None
+		'fix!: breaking change' -> 'fix'
 		"""
 		return get_conventional_type(self.title)
 
+	@property
+	def is_breaking(self) -> bool:
+		"""Check if this PR represents a breaking change.
+
+		Examples:
+		'feat!: breaking feature' -> True
+		'fix(api)!: breaking fix' -> True
+		'feat: regular feature' -> False
+		"""
+		return is_breaking_change(self.title)
+
 	def get_prompt(self, prompt_template: str, max_patch_size: int) -> str:
 		prompt = prompt_template
 

pretty_release_notes/models/release_notes.py

@@ -112,6 +112,7 @@ def is_reverted_or_revert(change):
 		if grouping and grouping.group_by_type:
 			# Group lines by type
 			grouped_lines: dict[str, list[ReleaseNotesLine]] = {}
+			breaking_lines: list[ReleaseNotesLine] = []
 			other_lines: list[ReleaseNotesLine] = []
 			new_contributor_lines: list[ReleaseNotesLine] = []
 
@@ -129,8 +130,11 @@ def is_reverted_or_revert(change):
 				):
 					continue
 
+				# Check for breaking changes first
+				if line.change and hasattr(line.change, "is_breaking") and line.change.is_breaking:
+					breaking_lines.append(line)
 				# Group by conventional type
-				if line.change and line.change.conventional_type:
+				elif line.change and line.change.conventional_type:
 					type_key = line.change.conventional_type
 					if type_key not in grouped_lines:
 						grouped_lines[type_key] = []
@@ -142,6 +146,13 @@ def is_reverted_or_revert(change):
 			# Build grouped output
 			sections = []
 
+			# Add breaking changes section first (highest priority)
+			if breaking_lines:
+				sections.append(f"## {grouping.breaking_changes_heading}")
+				for line in breaking_lines:
+					sections.append(str(line))
+				sections.append("")  # Empty line after section
+
 			# Add sections in a consistent order
 			type_order = ["feat", "fix", "perf", "docs", "refactor", "test", "build", "ci", "chore", "style", "revert"]
 

tests/test_models_utils.py

@@ -1,6 +1,6 @@
 """Tests for models utility functions."""
 
-from pretty_release_notes.models._utils import get_conventional_type
+from pretty_release_notes.models._utils import get_conventional_type, is_breaking_change
 
 
 class TestGetConventionalType:
@@ -68,3 +68,52 @@ def test_real_world_examples(self):
 		assert get_conventional_type('Revert "perf: timeout while renaming cost center"') is None
 		assert get_conventional_type(" Fix: Product Bundle Purchase Order Creation Logic") == "fix"
 		assert get_conventional_type("fix(accounting): correct tax calculation") == "fix"
+
+	def test_breaking_changes_with_exclamation(self):
+		"""Test that breaking changes with ! are still parsed correctly."""
+		assert get_conventional_type("feat!: breaking feature") == "feat"
+		assert get_conventional_type("fix!: breaking fix") == "fix"
+		assert get_conventional_type("fix(api)!: breaking fix with scope") == "fix"
+		assert get_conventional_type("perf!: breaking performance improvement") == "perf"
+
+
+class TestIsBreakingChange:
+	"""Test breaking change detection."""
+
+	def test_breaking_changes_with_exclamation(self):
+		"""Test detection of breaking changes with ! indicator."""
+		assert is_breaking_change("feat!: breaking feature") is True
+		assert is_breaking_change("fix!: breaking fix") is True
+		assert is_breaking_change("perf!: breaking performance improvement") is True
+
+	def test_breaking_changes_with_scope(self):
+		"""Test detection of breaking changes with scope."""
+		assert is_breaking_change("feat(api)!: breaking API change") is True
+		assert is_breaking_change("fix(core)!: breaking fix in core") is True
+		assert is_breaking_change("refactor(ui)!: breaking UI refactor") is True
+
+	def test_non_breaking_changes(self):
+		"""Test that regular changes are not detected as breaking."""
+		assert is_breaking_change("feat: regular feature") is False
+		assert is_breaking_change("fix: regular fix") is False
+		assert is_breaking_change("fix(api): regular fix with scope") is False
+
+	def test_case_insensitive(self):
+		"""Test that breaking change detection is case-insensitive."""
+		assert is_breaking_change("FEAT!: breaking feature") is True
+		assert is_breaking_change("Fix!: breaking fix") is True
+		assert is_breaking_change("Perf(api)!: breaking perf") is True
+
+	def test_with_whitespace(self):
+		"""Test that whitespace doesn't affect detection."""
+		assert is_breaking_change(" feat!: breaking feature") is True
+		assert is_breaking_change("  fix!: breaking fix  ") is True
+		assert is_breaking_change("\tfeat(api)!: breaking change") is True
+
+	def test_edge_cases(self):
+		"""Test edge cases."""
+		assert is_breaking_change("") is False
+		assert is_breaking_change("  ") is False
+		assert is_breaking_change("feat: no exclamation") is False
+		assert is_breaking_change("feat :! wrong format") is False
+		assert is_breaking_change("feat (scope)!: space before scope") is False