fix(skill): address review — mutable defaults, cache prefix anchor, docstring

- create_skill/update_skill: default labels/new_labels to None and coerce
  to [] in the body (avoid shared mutable default list)
- SkillCache.invalidate: anchor prefix match with '-' separator so a skill
  named 'foo' cannot evict 'foobar-*' cache entries
- get_skill: docstring fetch_timeout_seconds is seconds, not milliseconds

Author: Robin DE BASTOS

langfuse/_client/client.py

@@ -4088,7 +4088,7 @@ def get_skill(
             keyword argument. If not set, defaults to 60 seconds. Disables caching if set to 0.
             fallback: Optional[str]: The skill instructions to return if fetching the skill fails. Important on the first call where no cached skill is available. Follows Langfuse skill formatting with double curly braces for variables. Defaults to None.
             max_retries: Optional[int]: The maximum number of retries in case of API/network errors. Defaults to 2. The maximum value is 4. Retries have an exponential backoff with a maximum delay of 10 seconds.
-            fetch_timeout_seconds: Optional[int]: The timeout in milliseconds for fetching the skill. Defaults to the default timeout set on the SDK, which is 5 seconds per default.
+            fetch_timeout_seconds: Optional[int]: The timeout in seconds for fetching the skill. Defaults to the default timeout set on the SDK, which is 5 seconds per default.
 
         Returns:
             The skill object retrieved from the cache or directly fetched if not cached or expired, as a SkillClient.
@@ -4244,7 +4244,7 @@ def create_skill(
         name: str,
         instructions: str,
         description: Optional[str] = None,
-        labels: List[str] = [],
+        labels: Optional[List[str]] = None,
         tags: Optional[List[str]] = None,
         metadata: Optional[Any] = None,
         allowed_tools: Optional[List[str]] = None,
@@ -4265,6 +4265,8 @@ def create_skill(
         Returns:
             SkillClient: The created skill.
         """
+        labels = labels or []
+
         try:
             langfuse_logger.debug(f"Creating skill {name=}, {labels=}")
 
@@ -4295,7 +4297,7 @@ def update_skill(
         *,
         name: str,
         version: int,
-        new_labels: List[str] = [],
+        new_labels: Optional[List[str]] = None,
     ) -> Any:
         """Update an existing skill version in Langfuse. The Langfuse SDK skill cache is invalidated for all skills with the specified name.
 
@@ -4308,6 +4310,8 @@ def update_skill(
             Skill: The updated skill from the Langfuse API.
 
         """
+        new_labels = new_labels or []
+
         updated_skill = self.api.skill_version.update(
             name=self._url_encode(name),
             version=version,

langfuse/_utils/skill_cache.py

@@ -178,9 +178,10 @@ def delete(self, key: str) -> None:
 
     def invalidate(self, skill_name: str) -> None:
         """Invalidate all cached skills with the given skill name."""
+        prefix = skill_name + "-"
         with self._lock:
             for key in list(self._cache):
-                if key.startswith(skill_name):
+                if key.startswith(prefix):
                     del self._cache[key]
 
     def add_refresh_skill_task(self, key: str, fetch_func: Callable[[], None]) -> None: