Checkpoints and respawn

Package: demi.gameplay.checkpoints.

Stores the current checkpoint and queues respawn or scene-entrance requests. Exports demi.gameplay.checkpoints; depends on demi.gameplay.events. This checkout uses the renamed package; install from the local packages registry as described in package installation. Renaming a local source does not publish the new name to the hosted registry.

local Events = require("demi.gameplay.events")
local Checkpoints = require("demi.gameplay.checkpoints")

local events = Events.new()
local checkpoints = Checkpoints.new(events)
local requested
local unsubscribe = events:on("respawn_requested", function(value)
  requested = value
end)
checkpoints:set({
  id = "gate", scene = "scene://game/cave", entrance = "east", version = 1,
})
assert(checkpoints:respawn())
events:flush()
assert(requested.entrance == "east")
local saved = checkpoints:save()
unsubscribe()

set requires string id and scene, and retains optional entrance, prefab, data, and version (default 1). It queues checkpoint_changed. respawn returns false without a checkpoint; otherwise it queues respawn_requested. enter({ scene = ..., entrance = ..., data = ... }) requires string scene/entrance values and queues scene_entrance_requested without changing the current checkpoint.

The caller owns the event bus, flushes it at a chosen gameplay boundary, and unsubscribes listeners when their owner is destroyed. Listeners implement scene preparation, activation, positioning, and respawn rules. The package does not perform a transition or resolve scene, entrance, or prefab references.

save returns nil or a shallow copy of the checkpoint table; nested data remains shared. It does not write a file. load accepts a table with string id and scene, retains that table directly, and emits no event. It neither validates the remaining fields nor migrates versions. The game owns durable save formatting, validation, migrations, and disk I/O.

From the repository root, test with:

./build/linux-debug/demi package test packages/sources/demi.gameplay.checkpoints