The /api/status gateway_updated_at field and the gateway /health/detailed
updated_at field passed through whatever gateway_state.json contained,
untyped. All current writers emit RFC3339 via _utc_now_iso(), but legacy
gateways wrote unix epoch floats, and a corrupt or hand-edited state file
can inject numbers or arbitrary garbage — while the frontend types
(web/src/lib/api.ts) declare string | null.
Add normalize_updated_at() in gateway/status.py as the single funnel:
- str: accepted iff datetime.fromisoformat parses (trailing Z tolerated);
naive timestamps coerced to UTC; canonical isoformat returned
- int/float: treated as unix epoch seconds -> UTC ISO string, with a
plausibility guard (reject < 2000-01-01, > now+1day, non-finite)
- bool: rejected explicitly (int subclass, but never a timestamp)
- anything else: None
Apply it at both emit sites: the dashboard /api/status handler (covers
both the local read_runtime_status() branch and the remote
/health/detailed cross-container fallback branch) and the gateway API
server's /health/detailed response.
Contract tests: parametrized /api/status normalization (epoch float/int,
garbage string, None, bool, dict, absent key), remote-health numeric and
garbage bodies, dashboard shape test round-trip assertion, direct
normalize_updated_at units (range guards, Z suffix, naive coercion,
non-finite floats), and a write_runtime_status -> read_runtime_status
round-trip proving the writer side stays tz-aware parseable.