All JSON state writes (services.json, nodes.json, incidents.json,
deployments.json, runtime-summary.json, observer_checkpoint.json) now use
_atomic_write_json: write to a .tmp sibling, fsync, then os.replace.
This eliminates the truncated-write window that caused supervisors
reading mid-write files to see empty/partial JSON.
Also adds auto-resolution of phantom active incidents: if a service
reports status=healthy and its incident's last_occurrence is >30 min old,
the incident is resolved in _prune_stale_world. This clears false active
incidents accumulated from previous race-condition reads.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Oskar Kapala
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