Add instanceId to pool metrics for per-instance deduplication

[iscekic]

Summary

Adds a stable instanceId field to the pool metrics JSON logged every 30s (from #520). Without this, Axiom dashboard queries can't distinguish readings from different Vercel function instances, making it impossible to accurately compute global connection totals (sum across instances) vs per-instance stats.

The instanceId is generated once at module load as {region}-{timestamp}-{random}, e.g. iad1-1771954564449-k3x9f2. It's stable for the lifetime of the function instance.

Updated Axiom dashboard queries

With instanceId, the dashboard charts should use this pattern to get accurate global totals:

| summarize latest_total=arg_max(_time, total) by instanceId, bin(_time, 1m)
| summarize sum(latest_total) by bin(_time, 1m)

Changes

• src/lib/drizzle.ts — add instanceId field to pool metrics log output

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (1 files)

• src/lib/drizzle.ts — Added instanceId (region + timestamp + random suffix) to pool metrics logging for per-instance deduplication in Axiom. Clean, minimal change with no security, correctness, or performance concerns.