The part of gap 15 that doesn't need video, from the public documentation of prototype triggers, plugins/widgets and prototype expressions.
- **Controller buttons on key/gamepad triggers.** A key trigger's key can be a controller button: `Gamepad A` ... `Gamepad Home`, the standard gamepad layout's 17 buttons (face buttons by position, shoulders, triggers, View/Menu, stick presses, d-pad, Home). The engine keeps its input-agnostic model (a key trigger with a key name; `figcraft_doc::proto::GAMEPAD_BUTTONS`, `gamepad_button`, `is_gamepad_button`, `uses_gamepad`). The interaction editor gets a Controller menu beside the key field; the trigger list shows the button's own name.
- **Reading controllers.** A new `Services::gamepad_held()` (bitmask of held buttons; default none). The player polls it only while the presented prototype has a controller trigger and the window has the focus (about 30 times a second), plays each press once (held buttons don't repeat), and fires the first matching key/gamepad trigger on the screen like a key.
- Desktop, Windows: Windows.Gaming.Input (Xbox-compatible controllers) through the `windows` crate the app already depends on (one more feature flag, `Gaming_Input`; no new crate).
- Browser: the Gamepad API through `web-sys` (features `Gamepad`, `GamepadButton`, `GamepadMappingType`; standard-mapped controllers only).
- macOS, Linux, FreeBSD: no controllers yet (documented gap).
- Control channel: `ui.input {events: [{gamepad: "A" | "Gamepad A" | 0}]}` presses a button in the prototype playing (presenter, else preview pane); an error when nothing plays.
- **REST import** maps controller triggers (`device` other than `KEYBOARD`) to the button at the code's standard-layout index instead of skipping them; two buttons at once or an unknown code is skipped with a warning (`.fig` goes through the same path).
- **Widgets react to clicks in a presented prototype.** A click on a widget's clickable part in the presenter or the preview pane (when no interaction on the layer takes it) calls the plugin back through the canvas's own callback with the same sandbox limits, on the player's copy of the file (`widgets::click_on`, a scratch session holding the copy and the installed plugins): the widget changes in the prototype only, the file and its undo history stay untouched, restarting starts the widget over. Failures (plugin missing or failing) toast; toasts now also show over the full-window presenter.
- **Variable mode lookups.** Lookups (`accent[Dark]`, `mode(Theme)`), set-variable-mode affecting later expressions in the same interaction, and every operator the documentation lists already held; they are now behaviour cases. New `proto.evaluate {expression | expr, id?}` (MCP and agents) computes an expression where a layer's interaction would run, without changing anything. No other cheap expression gap found: every documented operator (numbers, text join, booleans, comparisons, negation, mode lookup) already existed.
- Docs: prototyping-parity (new rule rows, features, revision), target-app-parity area 13 and totals, ROADMAP, gaps.md gap 15, roadmap.md M5, mcp.md, plugins.md, control-protocol.md.
Dependencies: none added. Windows uses the existing `windows` 0.62 dependency with the `Gaming_Input` feature; the browser uses the existing `web-sys` with three more features. The usual Rust controller library (gilrs) was not taken: its Linux backend links the system's libudev (a C library, needing headers on CI and the FreeBSD job), which breaks the pure-Rust rule.
- Expressions as text: Expr::parse (variables by name, literals, and/or/not, comparisons,
arithmetic, text joins) with plain-English errors, type checks for conditions and set variable
values; display reads back as the same expression.
- New commands proto.action.add/set/remove/move and proto.conditional.addBlock/setCondition/
removeBlock edit single actions by path, inside conditionals too; `expression` text accepted by
these and proto.interaction.add/set.
- Interaction editor: an action list (open, move, remove, add), Add action > Conditional, if /
else if / else blocks with a condition builder (variable picker, operator, value or variable) or
an expression field with inline errors, nested actions, set variable expressions.
- Presenter: hotspot hints toggle (Options menu, proto.presentOptions {hotspotHints}), hotspots from
the engine (proto_run::hotspots) and in ui.inspect; an Inspect panel showing the hovered layer's
properties ({inspect}).
- Fields keep the keyboard on the click that opens them, and the Enter that commits a field no
longer reaches the shortcuts.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
