After a container exits, its .heartbeat file is left behind with the
mtime of its last SDK activity. When the same session spawns a new
container, the host sweep's ceiling check reads that stale mtime and
kills the freshly-spawned container within seconds — before the new
instance has had time to touch the file itself.
The sweep already has a carve-out for "no heartbeat file" (treated as a
fresh spawn, given grace), so simply removing the orphan at spawn time
restores the intended semantics.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
