The stages talk to the outside world through three interfaces, chosen by connectors.*:

The rule, and where it is not met yet

A seam is only proven by a second implementation. An interface with one is a guess about what varies, and it is wrong in the same direction every time: the single vendor's shape leaks in, and nobody notices until the second one arrives.

By that rule only the runner seam is proven. local — git worktree, tmux, the system crontab — is a genuinely different shape from Orca's worktrees and terminals, and keeping both working is what keeps the interface honest. The tracker and the SCM each have one implementation, and this page says so rather than implying a portability the harness does not have.

An unknown value fails closed, naming the interface to implement:

Unknown tracker connector "jira". Implement it against the TrackerConnector interface
and register it in resolveConnectors.

The local runner

connectors:
  runner: local
  local:
    worktreeRoot: ../.ak-worktrees
    tmuxBin: tmux
    cronMarker: '# ak-harness'

Two details worth knowing, both learned the hard way:

• send types the literal text first and presses Enter after. A newline inside a brief must not submit it early, which is exactly what happens when the text and the key are sent together.
• schedule only reconciles crontab lines carrying cronMarker. Every other line in your crontab is somebody else's, and a scheduler that rewrites the whole file once is a scheduler nobody installs twice.

Adding one

A new tracker or SCM is a factory in connectors.ts and a value in the enum — never a change in tick, deliver or release. Whatever that change forces the interface to grow is the measurement of how much of the first vendor had leaked into it.