jcoffey-dev
4df6931869
Agents now send an independent "still alive" record on a configurable schedule (seconds/minutes/hours, [heartbeat] in agent.toml), separate from real log traffic and tagged with a sentry.heartbeat attribute. No new wire protocol -- it's an ordinary record through the same PushBatch RPC/mTLS identity every log line already uses. Unavailability alerting reuses the existing absence-condition alert rule type unchanged; no new alerting code was needed. See /docs/agent-heartbeat-monitoring.md for the design and how to build the alert rule. While verifying the alert rule live, found that the query language's lexer never treated '-' as part of an identifier, so any unquoted hyphenated filter value -- including the reference doc's own canonical example, `host!=host-03` -- failed to parse at all. Fixed in api/internal/querylang/lexer/lexer.go with regression tests; a leading '-' still lexes as its own token so earliest=-1h/sort -count are unaffected.