Bevy economy system (docs-first stub)
Not a full port. Docs-first stub. Godot counterpart: godot-economy-system.
When to use
Load this when wallets, prices, or vendors change numbers. Item identity stays on bevy-inventory-system.
ECS shape
- Components: wallet amounts you define.
- Resources: run-wide tables live in a resource (bevy-data-resources), not an autoload.
- Systems: mutate those components on
Updateor the fixed timestep. Use.chain()when damage must land before death. - Messages: one-shot facts (hit, pickup, quest advance) go through bevy-events-messaging. This file does not add a new event type name.
Godot idea to Bevy idiom
| Idea | Bevy idiom (idea only) |
|---|---|
| Wallet | A component of currency amounts you define. |
| Price row | A resource table. |
| Transaction | A message. Do not mutate two wallets in unordered systems. |
Gaps
- No currency or market type exists in the opened Bevy modules.
- Persistence of the wallet is the save gap on bevy-save-load.
Expert Knowledge Delta
Library target in prose: Bevy 0.20.0. Lattice URLs stay unversioned.
Opened canon only: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. This file does not invent their struct APIs. Systems run in parallel unless .chain() orders the ones that conflict.
Who owns state
| Piece | Owner | Who may mutate | Schedule |
|---|---|---|---|
| Data on one entity | Component | One system via Query | Update or FixedMain |
| One value for the whole app | Resource | One system | Startup to insert, then the schedule that reads it |
| Spawn | Commands | The spawning system | Startup for the initial world; later schedules for runtime spawn |
| Order that must not race | .chain() | The chained systems only | Same schedule |
| Plugin boundary | Plugin | build registers systems and resources | Before the app runs |
Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.
Decision
| If you need | Do this | Do not |
|---|---|---|
| Per-entity data | Component + Query | A Godot node script |
| App-wide config or clock | Resource | Copy the value onto every entity |
| Stable simulation step | FixedMain and the Fixed clock | Tie simulation to raw frame Update |
| Startup spawn | Commands in Startup | Spawn from a render system |
| Cross-system notice that is not shared state | Message or observer slot in bevy-events-messaging | A new event type invented in this file |
| An API this skill did not open | A Gaps row | A fabricated crate (solver, navmesh module, net, XR) |
Load references/a-gate-notes.md for the same table plus the gap rule.
NEVER
-
Do not put
/0.20.0/in lattice URLs. WHY: permalinks stay onlatest. The 0.20.0 pin belongs in prose once. -
Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless
.chain()orders them. -
Do not invent a physics, navigation, networking, or XR crate here. WHY: those rows are gaps, blocked, or revisit.
-
No Godot node, resource, or signal types for this mechanic. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar.
-
No Godot types in Bevy code. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar.
-
No invented APIs or unnamed third-party crates as the chosen solver. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar.
-
No Creation Station content. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar.
-
No umbrella skill over Godot and Bevy. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar.
-
Do not mark this row
ported. It isdocs_mapped. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar.
Reference
docs.rs links use the unversioned latest permalink. The library pin on bevy-master stays 0.20.0.
Official Documentation
- Migration guides - Unversioned hop index.
- bevy crate - Unversioned API index. Feature list opened for 0.20.0.
- Assets - Official asset catalog. No third-party crate was selected.
- Examples - Example tree on the
latestbranch. - ECS -
Component, systems,Query,Startup,Update, and.chain(). - Plugins -
Plugin,DefaultPlugins,MinimalPlugins, andadd_plugins.
Related Skills
Prerequisites
- bevy-master - Hub and schedules.
- bevy-ecs-composition - Components and systems.
- bevy-inventory-system - Item stacks.
- bevy-save-load - Persist the wallet. Format still a gap.
- bevy-data-resources - Tables and definitions.
- bevy-events-messaging - One-shot facts.
Complements
- bevy-state-machines - Mode flags.
- godot-economy-system - Godot counterpart. Source idea only.
Downstream / consumers
- None yet.
Master
- bevy-master - Bevy router.


