Tenancy Parity: What Adding Users to a Single-Tenant Go API Actually Cost Me
Oct 30, 2026
5 min read
For most of its life, mule’s API had exactly one tenant: me. No users table, no keys — the API was the trust boundary, guarded by which host could reach it. That’s an honest design for a single-operator system. It’s also a wall between mule and anything resembling a fleet.
Herd H3.1 — shipped in commit 93aad23 as “tenancy parity” — tore the wall down and rebuilt it properly: users, API keys, and owner-scoped everything, at parity with forge, my memory service, which already had tenancy. “Parity” was the operative word. I didn’t design a tenancy model; I copied a proven one and paid the interesting costs in the seams. Here’s where the money went.