Give repeated call fixtures new identities until callbacks settle

When a voice workflow consults recent call history, retries and asynchronous callbacks, repeated tests should create fresh business identities and seed only the history each scenario requires. Clearing a shared row between calls can change later eligibility and allow a late callback to contaminate the next attempt. Preserve each attempt's evidence and retire its fixture only after telephone termination and application finalization both settle. Cleanup must follow the actual foreign-key graph and explicitly account for state that intentionally survives row deletion; a database cascade alone is not a reset contract.

Applies when: repeated end-to-end calls mutate history, scheduling or notification state. Keywords: call fixture reset history callbacks isolation retries cleanup ownership