Generate .gitattributes to hide generated skills in PR diffs

sync_ai_rules/__main__.py

@@ -11,6 +11,8 @@
 from sync_ai_rules.core.rule_metadata import RuleMetadata
 from sync_ai_rules.file_updater import update_documentation_file
 
+_GITATTRIBUTES_HEADER = "# Auto-generated by sync-ai-rules hook. Do not edit.\n"
+
 
 def get_category(file_path: str, source_dir: str) -> str:
     """Extract category from file path relative to source directory."""
@@ -58,6 +60,15 @@ def scan_and_parse(parser, source_dir: str, project_root: str) -> List[RuleMetad
     return rules
 
 
+def _write_gitattributes(project_root: str, patterns: List[str]) -> None:
+    """Write .gitattributes marking generated files as linguist-generated."""
+    lines = [_GITATTRIBUTES_HEADER]
+    lines.extend(f"{p} linguist-generated\n" for p in patterns)
+    file_path = os.path.join(project_root, ".gitattributes")
+    with open(file_path, "w", encoding="utf-8") as f:
+        f.writelines(lines)
+
+
 def main():
     """Main orchestration: load pipelines → parse → generate → update files."""
     # Setup
@@ -101,6 +112,14 @@ def main():
                 status = "✓" if success else "✗"
                 print(f"  {status} {message}")
 
+    # Collect gitattributes patterns from all generators and write .gitattributes
+    all_patterns: List[str] = []
+    for pipeline in plugin_manager.pipelines:
+        all_patterns.extend(pipeline.generator.gitattributes_patterns)
+
+    if all_patterns:
+        _write_gitattributes(project_root, sorted(set(all_patterns)))
+
     print("\n✓ Rules synchronization completed!")
 
 

sync_ai_rules/core/generator_interface.py

@@ -27,14 +27,17 @@ def generate(self, rules: Dict[str, List[RuleMetadata]], config: Dict[str, Any])
     def get_section_markers(self) -> tuple[str, str]:
         """Return start and end markers for auto-generated section."""
 
+    @property
+    def gitattributes_patterns(self) -> List[str]:
+        """Glob patterns (repo-root-relative) to mark as linguist-generated in .gitattributes."""
+        return []
+
     @property
     def is_multi_file(self) -> bool:
         """Whether this generator creates files directly via generate_files()."""
         return False
 
-    def generate_files(
-        self, rules: Dict[str, List[RuleMetadata]], project_root: str
-    ) -> None:
+    def generate_files(self, rules: Dict[str, List[RuleMetadata]], project_root: str) -> None:
         """Generate multiple files directly. Only called when is_multi_file is True."""
         raise NotImplementedError(
             f"{type(self).__name__} sets is_multi_file=True but does not implement generate_files()"

sync_ai_rules/generators/base_generator.py

@@ -18,6 +18,10 @@ def default_filenames(self) -> List[str]:
             ".github/copilot-instructions.md",
         ]
 
+    @property
+    def gitattributes_patterns(self) -> List[str]:
+        return self.default_filenames
+
     def _format_heading(self, category: str) -> str:
         """Format category as heading."""
         return category.replace("-", " ").replace("_", " ").title()

sync_ai_rules/generators/skills_generator.py

@@ -36,13 +36,15 @@ def generate(self, rules: Dict[str, List[RuleMetadata]], config: Dict[str, Any])
         total = sum(len(r) for r in rules.values())
         return f"Generated {total} skills in {len(rules)} categories"
 
+    @property
+    def gitattributes_patterns(self) -> List[str]:
+        return [".claude/skills/generated_*/SKILL.md"]
+
     @property
     def is_multi_file(self) -> bool:
         return True
 
-    def generate_files(
-        self, rules: Dict[str, List[RuleMetadata]], project_root: str
-    ) -> None:
+    def generate_files(self, rules: Dict[str, List[RuleMetadata]], project_root: str) -> None:
         """Generate skill files as direct children of .claude/skills/."""
         skills_root = os.path.join(project_root, _SKILLS_DIR)
 
@@ -82,11 +84,11 @@ def _strip_source_prefix(relative_path: str) -> str:
     """Strip the .cursor/rules/ prefix from a rule's relative path."""
     prefix = _SOURCE_DIR + os.sep
     if relative_path.startswith(prefix):
-        return relative_path[len(prefix):]
+        return relative_path[len(prefix) :]
     # Also handle forward-slash separators
     prefix_fwd = _SOURCE_DIR + "/"
     if relative_path.startswith(prefix_fwd):
-        return relative_path[len(prefix_fwd):]
+        return relative_path[len(prefix_fwd) :]
     return relative_path
 
 

test/after/.gitattributes

@@ -0,0 +1,4 @@
+# Auto-generated by sync-ai-rules hook. Do not edit.
+.claude/skills/generated_*/SKILL.md linguist-generated
+.github/copilot-instructions.md linguist-generated
+AGENTS.md linguist-generated