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ecs-persistence: apply a snapshot's values onto an existing entity (a persisted setting on a startup entity) #249
Description
Summary
Spawning from a snapshot with match keeps the world's values for what it matches, and nothing applies a snapshot's values onto an existing entity. So an entity the app's own startup system creates (and persistence should only update) can't be a persisted setting.
Case (mecs, @adobe/ecs-persistence 0.1.0)
The camera's orbit (target, distance, angles) is a component of an entity that spawnOrbitView makes at startup. We want it saved as a setting (inSettings, kept on the machine, shared by tabs). Restoring with spawn({ world, snapshot, entities: false, match }) either leaves the startup value (match keeps the world's) or, without match, spawns a second view.
Requested
An option to apply the snapshot's values onto the matched entity: spawn({ ..., match, update: true }), or a separate apply({ world, snapshot, match }), writing the snapshot's persisted components onto the entity that match finds, and leaving other components as they are.
Notes
Settings already work for resources; this is the component half.
Activity
krisnye commentedon Nov 1, 2026
Addressed in #250 (Adobe-Firefly/ecs#9) as an option on
spawnrather than a separateapply, so the entity map and reference rewriting stay one pass:spawn({ world, snapshot, match, update: true })writes a matched row's saved components onto the entity it matches, ascommands.addwould, leaving its other components. Corecommands.spawnTablestakes the sameupdate. The settings chapter of the persistence guide restores a startup entity's component this way.