When handling errors, ensure you don’t (1) mask the original failure, (2) violate the intended timeout/retry/cleanup boundaries, or (3) make recovery decisions without explicit evidence.

Standards 1) Cleanup must never throw / must not mask the real exception

• Initialize fields used in finally (e.g., worker/thread handles) or guard with getattr.
• Never let error-handling or teardown code raise unless you are explicitly replacing the original error.

   class Runner:
       def __init__(self):
           self._tts_playback_thread = None  # initialize for finally safety

       def run(self):
           try:
               ...
           finally:
               t = getattr(self, "_tts_playback_thread", None)
               if t and t.is_alive():
                   t.join(timeout=5)

2) Honor deadlines everywhere (especially after streaming/pipes hit EOF)

• Don’t “fall through” into unbounded waits after partial progress.
• Keep a single deadline source of truth and ensure the termination path is always reachable.

3) Cleanup must cover the full resource scope

• If you spawn detached/different process trees, terminate the process group (or equivalent scope), not only the parent PID.
• For multi-step operations, ensure the rollback/cleanup is consistent with the failure point.

4) Recovery decisions must be evidence-gated

• Separate “definitive miss” from “inconclusive probe.” Only trigger fallback when probes are inconclusive (or when the code explicitly models the condition).
• Avoid broad except Exception that collapses unrelated failures into the same recovery.

5) Error ordering: validate ‘not found’ before operations that can raise 400/validation/unknown-task errors

• Ensure the API returns the intended status (e.g., 404 for missing task) by checking existence before calling functions that validate inputs and may raise.

6) Preserve best-effort behavior where it was intentional

• If a route/feature previously returned a partial result on transient DB/tool errors, keep that contract; don’t replace best-effort with hard failure unless the user-visible contract changes.

Applying this standard will prevent masked exceptions, unblock deterministic cleanup/timeout behavior, and keep recovery logic correct and testable.