fix: stabilize pii filter stub generation

Signed-off-by: lucarlig <luca.carlig@ibm.com>

Author: lucarlig

plugins/rust/python-package/pii_filter/cpex_pii_filter/pii_filter_rust/__init__.pyi

@@ -12,29 +12,29 @@ __all__ = [
 class PIIDetectorRust:
     r"""
     Main PII detector exposed to Python
-    
+
     # Example (Python)
     ```python
     from cpex_pii_filter import PIIDetectorRust
-    
+
     config = {"detect_ssn": True, "detect_email": True}
     detector = PIIDetectorRust(config)
-    
+
     text = "My SSN is 123-45-6789 and email is john@example.com"
     detections = detector.detect(text)
     print(detections)  # {"ssn": [...], "email": [...]}
-    
+
     masked = detector.mask(text, detections)
     print(masked)  # "My SSN is [REDACTED] and email is [REDACTED]"
     ```
     """
     def __new__(cls, config: typing.Any) -> PIIDetectorRust:
         r"""
         Create a new PII detector
-        
+
         # Arguments
         * `config` - Python dictionary or Pydantic model with configuration
-        
+
         # Configuration Keys
         * `detect_ssn` (bool): Detect Social Security Numbers
         * `detect_bsn` (bool): Detect Dutch citizen service numbers
@@ -55,16 +55,16 @@ class PIIDetectorRust:
         * `max_text_bytes` (int): Maximum text payload size to inspect
         * `max_nested_depth` (int): Maximum nested container depth to inspect
         * `max_collection_items` (int): Maximum items to inspect per collection
-        * `custom_patterns` (list[dict]): Additional regex-based PII patterns
-        * `whitelist_patterns` (list[str]): Regex patterns to exclude from detection
+        * `custom_patterns` (`list[dict]`): Additional regex-based PII patterns
+        * `whitelist_patterns` (`list[str]`): Regex patterns to exclude from detection
         """
     def detect(self, text: builtins.str) -> typing.Any:
         r"""
         Detect PII in text
-        
+
         # Arguments
         * `text` - Text to scan for PII
-        
+
         # Returns
         Dictionary mapping PII type to list of detections:
         ```python
@@ -81,22 +81,22 @@ class PIIDetectorRust:
     def mask(self, text: builtins.str, detections: typing.Any) -> builtins.str:
         r"""
         Mask detected PII in text
-        
+
         # Arguments
         * `text` - Original text
         * `detections` - Detection results from detect()
-        
+
         # Returns
         Masked text with PII replaced
         """
     def process_nested(self, data: typing.Any, path: builtins.str) -> tuple[builtins.bool, typing.Any, typing.Any]:
         r"""
         Process nested data structures (dicts, lists, strings)
-        
+
         # Arguments
         * `data` - Python object (dict, list, str, or other)
         * `path` - Current path in the structure (for logging)
-        
+
         # Returns
         Tuple of (modified: bool, new_data: Any, detections: dict)
         """
@@ -108,4 +108,3 @@ class PIIFilterPluginCore:
     def prompt_post_fetch(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...
     def tool_pre_invoke(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...
     def tool_post_invoke(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...
-

plugins/rust/python-package/pii_filter/src/bin/stub_gen.rs

@@ -18,6 +18,17 @@ const CURATED_ALL_ENTRY: &str = "\"PIIDetectorRust\",\n    \"PIIFilterPluginCore
 const PLUGIN_CORE_CLASS_MARKER: &str = "class PIIFilterPluginCore:";
 const PLUGIN_CORE_CLASS_DEF: &str = "\n\n@typing.final\nclass PIIFilterPluginCore:\n    def __new__(cls, config: typing.Any) -> PIIFilterPluginCore: ...\n    def prompt_pre_fetch(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...\n    def prompt_post_fetch(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...\n    def tool_pre_invoke(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...\n    def tool_post_invoke(self, payload: typing.Any, context: typing.Any) -> typing.Any: ...\n";
 
+fn normalize_stub_content(content: &str) -> String {
+    let mut lines = content.lines().map(str::trim_end).collect::<Vec<_>>();
+    while matches!(lines.last(), Some(line) if line.is_empty()) {
+        lines.pop();
+    }
+
+    let mut normalized = lines.join("\n");
+    normalized.push('\n');
+    normalized
+}
+
 fn curate_extension_stub_content(content: &str) -> String {
     let mut curated = content.replace(GENERATED_ALL_MARKER, CURATED_ALL_ENTRY);
     if !curated.contains(PLUGIN_CORE_CLASS_MARKER) {
@@ -33,7 +44,7 @@ fn curate_extension_stub_content(content: &str) -> String {
         "curated extension stub is missing PIIFilterPluginCore class definition",
     );
 
-    curated
+    normalize_stub_content(&curated)
 }
 
 fn curate_extension_stub() {
@@ -53,7 +64,8 @@ fn remove_orphan_extension_stub() {
 fn curate_top_level_stub() {
     let stub_path = Path::new("cpex_pii_filter/__init__.pyi");
     let content = "# This file is automatically generated by pyo3_stub_gen\n# ruff: noqa: E501, F401, F403, F405\n\nfrom .pii_filter import PIIFilterPlugin\nfrom .pii_filter_rust import PIIDetectorRust\n\n__all__ = [\n    \"PIIDetectorRust\",\n    \"PIIFilterPlugin\",\n]\n";
-    fs::write(stub_path, content).expect("Failed to write curated top-level stub file");
+    fs::write(stub_path, normalize_stub_content(content))
+        .expect("Failed to write curated top-level stub file");
 }
 
 fn main() {
@@ -84,6 +96,17 @@ mod tests {
         assert!(curated.contains(CURATED_ALL_ENTRY));
     }
 
+    #[test]
+    fn test_curate_extension_stub_normalizes_trailing_whitespace() {
+        let generated = "# This file is automatically generated by pyo3_stub_gen\n# ruff: noqa: E501, F401, F403, F405\n\nimport typing\n\n__all__ = [\n    \"PIIDetectorRust\",\n]\n\nclass PIIDetectorRust:\n    r\"\"\"\n    Example text\n    \n    More text\n    \"\"\"\n";
+
+        let curated = curate_extension_stub_content(generated);
+
+        assert!(!curated.contains("    \n"));
+        assert!(curated.ends_with('\n'));
+        assert!(!curated.ends_with("\n\n"));
+    }
+
     #[test]
     #[should_panic(expected = "missing PIIFilterPluginCore in __all__")]
     fn test_curate_extension_stub_panics_when_expected_export_injection_fails() {