Zero-dependency local agent: collect one snapshot through the shared
metrics.js, POST it once to /hosts/<id>, exit. Cron runs it every five
minutes. Nothing is queued and nothing is replayed — a heartbeat from five
minutes ago describes a machine that no longer exists, so a failed push is
logged and dropped rather than spooled.
run-push.sh sources ~/.config/maximus-host-agent.env (mode 600), refuses to
start when HOSTS_API_URL, HOSTS_INGEST_TOKEN or HOST_ID is missing, and never
enables shell tracing: the script is meant to be piped into `logger`, where
`set -x` would echo the ingest token into /var/log/syslog and journald for
good. Same reason the failure path reports only err.code and the HTTP status —
never an error object, request options, headers, or a response body. The cost
is accepted: a 400 says the payload was rejected, not why.
50 tests, including two that spawn the real process against a failing server
and scan its actual stdout and stderr for any five-character fragment of the
token. The payload is pinned against the server's own sanitizeSnapshot(), and
one case pushes a real collectMetrics() snapshot through the real ingestion
handler, so a drift between agent and server turns a test red instead of
producing a 400 at 3 a.m. on the ThinkPad.
agent/ stays out of the Docker image: the COPY line is untouched, and a test
pins that it copies files one by one and never names the directory.
Installing on a workstation — frozen copy, env file, crontab line, dry run,
and why two machines must never share a HOST_ID — is documented in
agent/README.md. The install itself belongs to the commissioning issue.
Resolves#15
