Factory

Free Battery Factory builds small sync-first batteries for software boundaries.

batpak stands for battery pack. The name is a model, not decoration: a battery owns one boundary, stores local truth, exposes named terminals, and can be wired into a larger host without becoming the whole machine.

The core sentence:

batpak is a battery pack for application truth: small, sync-first, append-only cells that can be replayed, verified, and wired into larger systems.

The factory sentence:

The Free Battery Factory makes batteries for software boundaries.

The rule:

A battery does not own the machine. It powers one boundary.

Use factory words for mental model and composition. Use engineering words for exact API contracts.

Product Pressure Boundary

The downstream product direction is to describe a pain, shape a living work artifact, and project it wherever the work needs to happen. That sentence is pressure on BatPAK’s naming and boundaries, not a BatPAK feature list.

BatPAK supplies durable append/event truth, receipts, replay, projections as mechanisms, evidence, and opaque extension bytes. Higher layers own the product, agent-framework and downstream product semantics that interpret those bytes.

Factory Contract

Every shipped battery should preserve the same shape:

• explicit terminals
• bounded state
• receipt-bearing operations
• replayable source truth where applicable
• no hidden runtime ownership
• conformance checks that can be run from the root command surface

Command Counter

Humans and agents enter through just at the repository root:

just list
just inspect
just ledger-list
just context
just verify
just perf-gates
just loom
just seal
just ship dry

just is the command counter. xtask is the factory machinery. ast-grep is the semantic inspection camera. Tests inspect behavior. Receipts preserve evidence.

The opt-in factory ledger (just ledger-run -- …, just ledger-list, just ledger-run-gate …) records command proof events into bpk-lib/target/factory-ledger/store/. Normal builds do not depend on it; use it when you want a queryable local proof trail for wrapped commands such as just ledger-run -- just verify.

Command events (factory.command.*) record that a wrapped command ran. Gate events (factory.gate.completed) record which named proof that command represented when using just ledger-run-gate ….

The opt-in context packet (just context) writes a portable context handoff artifact to bpk-lib/target/context/latest.json and latest.md. It captures git state, stacked-PR hints, factory-ledger tail, and boundary reminders for agent/operator handoff. It is local tooling only — not an external context-profile spec, not a CI gate.

The manual proof commands (just perf-gates, just loom) run the existing xtask proof surfaces from the root counter. They are release-confidence tools: perf gates are hardware-dependent and should run alone; loom explores bounded concurrency schedules. They do not change the public Rust API.

Current Batteries

The shipped family is described in 04_BATTERIES.md. Do not treat reserved names as shipped products.