Callers Knock With the Kit, Not With a Private Dialect
Sibling Kit ships a terminal client — KitTerminalClient — so family apps do not invent a second way to ask Smolder for a pane. Waygate already knocks with it when a folder wants a split. Watchfire already knocks with it when a host wants a seat. That is consume-the-kit, not retell-the-kit. This quest will not teach how the kit is vendored, how drift is checked, or how a pin moves. Those sentences belong to the kit's own quest. Here the product fact is: callers use that client, and they never add a raw input method beside it.
A private dialect per sibling is how the door grows four generic keyboards with four names. The kit client is the shared mouth. If a new family app needs a terminal, it takes the client, it does not take a screenshot of Waygate's call and mutate it. Mutation is how "open folder" quietly becomes "type this string," and the last lesson's refusal dies in a helper function.
Smolder Owns Sessions and the Wire; Callers Own Policy
The split of ownership is load-bearing. Smolder owns the sessions and the wire contract: which pane exists, which PTY, which receipt, which stable target ID. Callers own folder, host, and seat policy: which directory is this, which machine, which Anvil seat name. The client carries the caller's policy to the door. The door does not guess a folder from a window title, and the caller does not pick a PTY. Crossing that line is how Waygate starts caring about emulator state, or Smolder starts caring about Watchfire's host catalog.
Receipts travel back through the same client. The caller holds an ID it can mention later. It does not hold a file descriptor into someone else's PTY. If a sibling finds itself wanting to "just send a few bytes" after the launch, it has left policy and entered input, and the client should not grow a method for that. The human at the glass, or a draft outside the PTY, is the rest of this track.
Two Callers Already Prove the Shape
Waygate is a dual-pane file workbench. Its need is spatial: this folder, a new leaf, maybe next to the one I am looking at. Watchfire is fleet control. Its need is a seat on a host, named, not a pile of untitled shells. Both needs fit typed launches. Neither need is "type cd into whichever pane looks right." If a future sibling cannot state its need in folder-host-seat language, the answer is not a new verb on the client. The answer is a conversation at the plan gate about whether the need is a door need at all.
Keep the kit in one sentence and the door in another. The kit is plumbing the family already shares. The door is Smolder's product boundary: launches and receipts, no raw input, loopback only. Confusing those sentences is how a plumbing update gets blamed for a policy leak, or a policy leak gets hidden inside a plumbing update.