**A prototyping behaviour suite written from the public documentation, and fixes for every divergence it found.** Each documented rule on triggers, actions, overlays, animations, easing, scrolling and interactive components is a case with what the rule implies and a one-line derivation; where the documentation is silent the case says so and pins today's behaviour. The model rules are table-driven tests in the engine; the player's are driven through egui headless (real pointer, key and timer input into the presenter) or on the player directly.
**Fixes (the suite failed on these before them)**
- **On drag follows its animation**: with a move, push or slide animation, only a drag that way starts it (a drag another way can scroll instead), and the animation follows the pointer while the button stays down, then plays on from there when it lets go (it played by time, and any drag direction fired it).
- **Key combinations**: a key trigger can be a combination (`Shift+K`, `Ctrl+Alt+Delete`, other spellings of the modifiers accepted); the modifiers held must match, so `K` no longer fires for Shift+K. The interaction editor's recorder records the modifiers held, and REST files' modifier key codes import as the combination (they imported as the key alone, with a warning).
- **Overlay timers**: an overlay's after-delay timer starts when the overlay opens, and again each time it opens (it was timed from when the screen under it arrived, so a toast opened late closed at once, and it fired only the first time).
- **Interactive components**: every instance plays the interactions on the variant it shows; an interaction on the instance with the same trigger wins. Before, instances played only interactions copied onto them when placed: an instance placed before its main got interactions did nothing, and one placed after kept the first variant's interactions after changing (a toggle went on but never off). New instances no longer copy them, and copies in older files give way to the variant shown (`proto_run::play_interactions`, on the player's copy).
- **Change to on nested instances** changes the instance whose variant set holds the destination (`proto_run::change_to_target`), not the innermost instance (an icon inside a button).
- **Springs**: the presets are physical springs (mass 1; stiffness / damping gentle 100/15, quick 300/20, bouncy 600/15, slow 80/20; they were ad-hoc curves), and every spring plays until it settles instead of being squeezed into the duration field's time; the settling time accounts for over-damped springs. The interaction editor shows the spring's duration in place of the duration field, with a tooltip.
- **Smart animate overshoot**: matched layers follow spring and back easings past their end and back (they snapped to the end once the curve passed 1).
- **Fixed layers on top**: fixed layers draw and take clicks above the content scrolling under them, wherever they are in the layer list (the file's order doesn't change).
**Missing documented setting, added**
- **Scroll to offset**: `{type: "scrollTo", dest, offset: [x, y]}` stops the layer that far from the top-left of the innermost frame scrolling it (room for a fixed header); X / Y fields in the interaction editor; files carry it only when set.
- Already there and now covered by the suite: click / mouse down / mouse up / while pressing / while hovering / mouse enter / mouse leave / after delay, nested hotspot priority and click-through, navigate (closing overlays), back with the reversed animation, restart, overlay stacking / swap / close / close on a click outside, change to with smart animate, reversed directional transitions, easing curves.
New strings go through `tr(...)` with `en.toml` / `es.toml` entries. No new command ids. The player still draws nothing while idle: the drag-follow only runs during an animation, and fixed layers and instance interactions are worked out once per layout, not per frame.
Progress docs per craftrules standards/progress-docs.md: target-app parity, gaps, roadmap with alpha gate, readiness by audience (full / mainstream / essentials) with Opus 5.5 hours, and auto layout, components, prototyping, dev mode, collaboration, format, hardware, UI and localization parity docs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
bflatastic
Brandon Thomas