- heartbeat loop continues past a raising activity callback instead of
silently stopping (matches delegate_task / touch_activity_if_due
swallow-and-continue semantics) — one transient error must not drop
watchdog protection for the rest of a long job
- hard 6h elapsed ceiling so a wedged job under HERMES_CRON_TIMEOUT=0
(unlimited child watchdog) cannot mask the gateway watchdog forever
- public get_activity_callback() accessor in tools/environments/base.py
instead of importing the private _get_activity_callback cross-module
- tests: deterministic heartbeat test (event-gated, no timing sleep),
no-callback test now asserts the thread is truly never created, new
exception-survival guard; dead started event removed
- fix comment: delegate_task heartbeat cadence is 30s, not 10s
8fd1a68106