Terminals

A terminal is a named boundary where a battery accepts, denies, emits, or observes work.

Terminals are authority boundaries, not just function names. If work crosses from a host into a battery, or from one battery into another, the route must be visible.

Terminal Rules

• Terminals name what may cross the boundary.
• Terminals apply policy before durable state changes.
• Terminals emit receipts or typed outcomes for durable operations.
• Terminals do not hide runtime ownership.
• Hidden wires are bugs.

Today In batpak

Current terminal-shaped surfaces include:

• Store public methods
• append and batch append paths
• gate evaluation and denial paths
• cursor and subscription delivery surfaces
• projection and replay entry points
• netbat routes and operation handling surfaces

The reference NETBAT profile exposes ten operations: five core substrate terminals plus one liveness terminal and four domain-neutral evidence.* terminals.

• system.heartbeat is the liveness terminal.
• bank.commit is the write terminal.
• event.get is the point-read terminal.
• event.query is the commit-order paging terminal.
• receipt.verify is the proof terminal for ack-shaped append receipts.
• event.walk is the relation-walk terminal for bounded hash-chain ancestry.
• evidence.chain_walk is the chain-walk evidence report terminal.
• evidence.store_resource is the store-resource snapshot evidence terminal.
• evidence.read_walk is the read-walk evidence report terminal.
• evidence.projection_run is the projection-run evidence terminal. The reference host registers no projections, so this op is advertised on the wire but answers with an unknown-projection handler error unless an embedder registers projections.

Push subscription is lossy awareness, not replay. Durable replay uses commit-order query pages, durable cursor pull surfaces, or projection-owned pull surfaces.

Run cargo test -p netbat to prove the ten reference NETBAT operations through the Rust wire and stream runtime surfaces.

Terminal Versus Function

A function is an implementation unit. A terminal is a boundary promise.

Many functions are not terminals. A terminal is where authority, input, evidence, or durable state crosses a meaningful boundary.

Breakers

Gates and policy checks act like breakers. They do not make work disappear; they accept, deny, or classify it with evidence.