Module caller 

Stable per-caller key. Identifies the process tree that invoked vs so different shells / agents get different auto-sessions.

Key is <parent_pid>-<parent_start_time>. Parent start time disambiguates PID reuse: even if the OS recycles a PID after a parent exits, the new process has a different start time.

Functions

caller_key

Return the stable caller key, or None if either the parent PID could not be read (extremely rare; would mean the kernel refused to answer). The key is filename-safe: only digits and a single hyphen.