feat: script system ordering by label/set and run conditions

AGENTS.md

@@ -21,8 +21,8 @@ Multi-language scripting for Bevy (Lua, Rune). Scripts are Bevy assets; they acc
 * Languages dispatch every script operation through `bindings::dispatch` (indexing, operators, static members, printing, iteration) and only convert values and deliver method receivers; see `docs/src/Development/AddingLanguages/necessary-features.md`.
 * Functions available on every type (e.g. the shared `new` constructor) are registered on `StaticTypeRef` (`FunctionScope::all_types()`) and bound to the type at lookup by currying a `ScriptValue::Type` (no allocation). Enum variants (`EnumVariantRef`) are resolved the same way, lazily.
 * There are no script globals besides the builtins, hardcoded in `bindings::builtins` (`import_namespace`, `export_namespace`) plus the language's `register_callback`; the function registry is keyed by type only. `world` is the `bms.world` namespace value. Functions which don't belong to a type are members of a namespace (`#[script_bindings(namespace = "...")] impl NamespaceMembers`, stored in `AppScriptNamespaceMembers`), i.e. `import_namespace("bms").log_info`; the running script's entity and handle are `bms.current_entity()` / `bms.current_script()`, looked up only when called.
-* Every type known to scripts lives in a namespace: the crate defining it, unless overridden with `ScriptNamespace` type data (`script_bindings(namespace = ...)`); BMS' own types are in `bms`. Scripts register components and events only into `script.*` namespaces. `import_namespace(path)` returns a namespace's types (and exported functions), from the shared, lazily rebuilt `AppScriptTypeCatalogue` (`bindings/src/globals/catalogue.rs`).
-* `export_namespace` exposes a callback of the calling script as a function in a `script.*` namespace; calls run through the callback runners in the exporting script. A script's exports and observers are removed when it unloads (`remove_script_registrations`).
+* Every type known to scripts lives in a namespace: the crate defining it, unless overridden with `ScriptNamespace` type data (`script_bindings(namespace = ...)`); BMS' own types are in `bms`. Scripts register components, events and system sets only into `script.*` namespaces; Rust system sets are namespace members (`ScriptSystemSetAppExt`). `import_namespace(path)` returns a namespace's types (and exported functions), from the shared, lazily rebuilt `AppScriptTypeCatalogue` (`bindings/src/globals/catalogue.rs`).
+* `export_namespace` exposes a callback of the calling script as a function in a `script.*` namespace; calls run through the callback runners in the exporting script. A script's exports, system sets (from their namespace only) and observers are removed when it unloads (`remove_script_registrations`).
 * Script observers (`world.add_observer`) run their callbacks from a command through `AppScriptCallbackRunners::run_or_queue`, never re-entering a busy context.
 * The Rune backend (`crates/languages/bevy_mod_scripting_rune`) differs from Lua in how members are reached (names are registered up front, the context is rebuilt when new ones appear), has no top level code (`pub fn main()` runs on load), no shared globals (`state()`), and catches errors with `catch(|| ..)`; see its crate docs. Rune scripts (`.rn`) have tests next to the Lua ones, run with the `rune` feature.
 * Feature flags select language and which Bevy crate bindings are compiled in; exactly one Lua variant must be chosen.