gamedev-the-steward/docs/ECONOMIC_EVENTS.md

The Steward — Economic Event Stream

Current contract

Every successful food or wood movement creates an EconomicEventRecord using the applicable event type:

resource_extracted
storage_deposited
storage_withdrawn
item_consumed

Each record contains a monotonically increasing event ID, event type, simulation tick, actor ID, source ID, destination ID, item ID, and transferred amount, plus the authoritative world position captured when the fact is recorded. NPC events preserve their authoritative interaction target (or NPC position when no target applies); player extraction/depletion events preserve the ResourceNode interaction position. Actor -1 identifies a player-triggered extraction until persistent player identity is introduced.

Events are immutable facts about completed transfers. They do not perform the transaction and are not replayed to reconstruct current state. Resource, inventory, and storage records remain authoritative.

SimulationEventLog owns ordered event identity, append/restore behavior, and history/rate queries, including exact lookup through get_by_id(). VillageEconomy performs transactions and requests event records only after state changes succeed; SimulationManager remains the public signal boundary used by presentation.

An action whose definition-backed completion cost becomes unavailable records a zero-amount task_blocked narrative fact with the action and shortfall reason. This makes late contention inspectable without pretending that a transfer occurred.

Persistence and determinism

SimulationStateRecord schema v5 stores the ordered event stream, next_event_id, directed relationships that may reference an exact event, and per-NPC known-event references. Schema v1 and v2 saves migrate to an empty stream beginning at ID zero. Parsing rejects duplicate event IDs, invalid or duplicate knowledge references, relationship causes the observer does not know, and a next ID that could collide with restored history.

A successful food deposit can currently raise a hungry familiar NPC's directed trust in its contributor only when that NPC knows the event. The actor and living NPCs within the bounded witness radius receive a KnownEventStateRecord at record time. Witness distance uses the event's captured position, never the actor's later location. The relationship stores the same deposit event ID rather than copied prose, so the inspector can resolve and display the real completed fact. This is a first evidence-gated causal consumer of the event stream, not general event sourcing.

The food-loop regression verifies this chain:

bush -> NPC inventory -> village pantry -> NPC inventory -> consumed

It checks event order, stable IDs, exact quantities, conservation, and save/restore continuity.

Presentation

npc_inventory_changed is a transient presentation signal. The active NpcVisual shows a small food sack whenever its authoritative inventory contains food. A newly loaded visual derives the same state directly from the NPC record, so unloading presentation does not lose the fact.

Deliberate limits

The stream is currently kept in full for the small simulation garden. Before large populations or long-running worlds, add measured retention, archival/summary rules, and query indexes. Proximity is the only current witness rule; line of sight, hearing, acquisition provenance, communication, secrecy, false beliefs, multi-event causal graphs, and memory retention belong in later event/history slices. They should extend this record family without making prose authoritative or recomputing old evidence from current positions.