`SelectiveSampleService` uses a mutable default argument

[sequoiap]

pyrolab/drivers/sample.py:192:

class SelectiveSampleService(Service):
    def __init__(self, items: List[Any] = []) -> None:
        self._items = items

The default list is created once at function definition and shared by every instance that does not pass items. sort(), set_item() and the items setter all mutate it, so state leaks between instances.

This matters more than usual here because the class is a hosted service: under instance_mode="session" each client connection gets its own instance, all of which share the one default list; under "single" it is shared by definition. Either way, one client's set_item() is visible to the next.

It is also a sample service -- it is what users read when writing their own drivers, so the pattern propagates.

Fix:

def __init__(self, items: Optional[List[Any]] = None) -> None:
    self._items = list(items) if items is not None else []

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Found in a full-codebase audit at v0.4.0 (commit 1ce3146).