Bevy save and load (docs-first stub)
Not a full port. This file records what was opened and what was not. There is no Bevy save-slot API in the pages below.
When to use
Load this when a design asks to persist player progress. Route asset and scene spawning to bevy-asset-scenes. Keep save bytes as an explicit gap until a current page names the format.
ECS shape
- What exists: app-wide progress can be a
Resource(seebevy-data-resources). Level content loads throughAssetServerand may spawn withspawn_scene/queue_spawn_scene(bevy::scene, docs.rslatest, 0.20.0). - What was checked and rejected:
https://docs.rs/bevy/latest/bevy/scene/struct.DynamicScene.htmlreturned 404 on 2026-10-11. The live scene index documentsSceneandbsn!, not a save-file serializer. Do not callDynamicScene::serializefrom this skill. - Schedule: no save system is specified here. Do not invent a filesystem write inside
Update.
Godot idea to Bevy idiom
| Idea | Bevy idiom (idea only) |
|---|---|
| Resource file for designer data | An asset Handle, or a Resource you own in code |
| Packed scene instance | Scene spawn on bevy-asset-scenes |
| Player save slot | Not opened. Leave it as data you have not serialized yet |
Gaps
- No save path, slot index, version field, or RON/JSON writer was opened on docs.rs
latest. - Scene spawn is not a save game. Do not treat
bsn!as a user save. - Wasm has no general filesystem story on the pages opened for this batch. Do not invent one.
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
Resource,FileAccess, or config-file types. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. -
No
DynamicSceneor scene-file writer this file's opened pages do not list. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. -
No third-party save crates. 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_mappedbecause the gap was checked against live docs. 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.
- bevy::scene - Spawn API that is not a save format.
DynamicScenestruct URL 404. - bevy::asset - Disk assets, not player slots.
- Resources - App-wide data that a future save would have to name.
- Examples - Example tree on the
latestbranch.
Related Skills
Prerequisites
- bevy-master - Who owns which piece of state.
- bevy-data-resources -
ResourceversusComponent. - bevy-asset-scenes - Loading content. Not a save slot.
Complements
- godot-save-load-systems - Godot counterpart. Source idea only.
Downstream / consumers
- None until a save format is opened.
Master
- bevy-master - Bevy router.


