Query Probe

Diagnostic (read-only, metadata only). Default: issue ONE fat-row windowed SELECT at rows LIMIT and report status/latency/bytes/headers (page-size 504 onset). With burst=N: fire N light queries concurrently to trip the rate limit and report how many 200s vs 429s and the Retry-After (real ceiling, since PostHog sends no limit header on success). Never returns event rows.