Patterns

Each pattern here is one recurring job, done with Harness, Switchboard and Cairn together: what each tool carries, the config that wires them, and the trap that catches people. Teams building on the stack kept rebuilding these inside their own coordinators, so they are written down once.

Patterns live with the product that carries most of the weight. This index lists all of them:

Pattern	What it solves	Lives in
Author/reviewer pairs on different model families	a reviewer that doesn't share its author's blind spots, and never approves its own work	Harness
When to react to events and when to run on a schedule	doorbells for work that arrives, schedules for work that sweeps	Harness
Human in the loop through notifications, not a ticket queue (coming)	asking a person to sign off without making them drain a queue	Switchboard
Environment binding (coming)	one queue and endpoint per environment, refusing work that arrives on the wrong one	Switchboard
Receipts and evidence (coming)	what goes in Cairn, what goes in the tracker, and what goes in the repo	Cairn

Every pattern assumes the roles on the stack page: the tracker and the front door stay yours, Switchboard dispatches, Harness supervises, and Cairn keeps the evidence.