Use when building Bevy 0.19 UI with BSN scenes (the bsn! macro, scene functions, Children[], on() observers, #Name child-entity capture, SceneComponents) and/or bevy_feathers widgets (FeathersPlugins, UiTheme token overrides, @FeathersButton/@FeathersCheckbox, ThemeBackgroundColor/ThemeTextColor). Trigger whenever authoring or reviewing a Bevy 0.19 window/panel/widget, porting imperative bevy_ui spawning to bsn!, wiring a Feathers theme, or debugging why a bsn! tree won't compile, a Feathers button does nothing, or themed text/colors don't apply. Covers the idiomatic patterns, the real 0.19 API gaps, and the bundle-factory anti-pattern that makes BSN look worse than imperative.
Use when writing or reviewing Bevy 0.18 ECS code (systems, queries, components, bundles, plugins, states, events/messages, observers, transforms, hierarchy, change detection, run conditions, fixed timestep) or when adapting examples from the outdated Unofficial Bevy Cheat Book to current 0.18 APIs.
Use when working in the Lifthrasir codebase with its third-party Bevy 0.19 ecosystem crates — bevy_auto_plugin (the auto_* macro plugin system), bevy_common_assets, bevy_asset_loader, bevy_kira_audio (spatial), bevy_feathers, bevy_hanabi, bevy-persistent, moonshine-kind/-tag/-behavior, bevy_framepace, bevy_brp_extras. Covers correct APIs, this project's conventions, and known gotchas.
Use when exploring or extracting Ragnarok Online GRF archives in the Lifthrasir repo — listing files, finding a sprite/texture/map/model path, extracting SPR/ACT/GND/GAT/RSW/RSM/BMP assets, or inspecting GRF metadata. Covers the grf-utils CLI, the data.grf/en.grf locations, and the backslash + Korean (EUC-KR) filename gotchas.