Production economy mechanism: design decision record

This page records where production, consumption, and military supply belong in Canwu and why. Read it if you are deciding whether a new economic rule belongs in your application, in an optional extension, or in the simulation core.

Decision

Production, consumption, and military supply are built as optional extensions above canwu-api. Grain, factories, prices, armies, and historical resource maps stay in extensions, content packs, and host applications; the simulation core keeps only generic settlement.

Evidence behind the decision

A host fixture. Celestial Mandate, a downstream strategy game built on Canwu, first checked the boundary with a synthetic fixture against the Canwu 0.6 public API, using only host-owned plugins and no core change.
A running loop. The replaceable canwu-economy-reference integration runs a fourteen-month grain loop that uses real routing and transport types (cargo run -p canwu-economy-reference --example grain_loop).
Two independent consumers. canwu-production and the force-supply reference consumer (canwu-force-supply-reference) own different lifecycles yet use the same accounts, reservations, allocation, transfers, and fulfillment. Two independent users of one lifecycle were the condition for extracting a shared extension.
Scarcity and price-pressure reads. The reference integration adds evidence-based local scarcity and price-pressure projections. They are read models; a full market simulation is outside this delivery.

With that condition met, canwu-resource and canwu-production became publishable optional extensions. canwu-force-supply-reference and canwu-economy-reference remain unpublished, replaceable integrations.

Ownership

Owner	Owns
Simulation core	Admission, time and phase order, reservation allocation, declared reads and writes, atomic commit, rollback, evidence, visibility, persistence, and replay
`canwu-resource`	Resource definitions, units, accounts, protected floors, demands, reservations, allocation, transfers, consumption, loss, and fulfillment
`canwu-production`	Processes, production sites, facilities, capacity, work orders, work in progress, execution, projects, and output settlement
`canwu-transport` and `canwu-movement`	Itinerary, leg, custody-handoff, and capacity records (`canwu-transport`) and their lifecycle: movement orders, leg settlement, and capacity pools (`canwu-movement`). In-transit cargo balance, loss, acceptance, return, and destination credit stay in `canwu-resource`.
Population, production, and military domains	Forming demands and using exact fulfillment outcomes; each writes only its own state
Historical content	Places, deposits, processes, facilities, institutions, parameters, and provenance, with no special write path

Production sits above the conserved-resource layer. It owns versioned processes, work orders, work in progress, maintenance, and facilities, and hands output back to canwu-resource for crediting.

What it would take to move something into the core

This delivery adds no simulation-core query API and moves no domain rules into the core. A future full market, money, property, universal construction, or combat system would need the same kind of proof: independent consumers that share its lifecycle, plus a public-API fixture that fails without a core change. An architecture diagram alone is not enough.

What stays out of the simulation core

Historical goods, deposits, agricultural calendars, and era parameters.
A national price used as the truth about physical stock.
Automatic local capability from building levels, production methods, or technology unlocks.
A reachable route treated as a booking, departure, arrival, or usable delivery.
Transport execution records treated as the source of truth for cargo balance and loss.

See Production, resources, and transport: who owns what and the production, resources, and military supply case.