feat(frontend): live host-input capture for Mouse/Super Scope

CHANGELOG.md

@@ -27,6 +27,32 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   page" section for the full disposition and `to-dos/ROADMAP.md`/the approved UI/UX-parity plan
   for what fixing those three would actually require.
 
+### Added
+
+- **Live host-input capture for Mouse/Super Scope** (Phase A.2 of the UI/UX-parity ladder, new
+  `crate::peripherals`). `config.port2_peripheral`'s Settings selector already wired the emulated
+  hardware correctly since `v0.9.0`; now `egui::Context`'s pointer state actually drives it once
+  per frame — `EmuCore::set_mouse` from pointer delta + left/right buttons, `EmuCore::set_superscope`
+  from an absolute aim position mapped through the present path's own letterbox transform
+  (`Gfx::letterbox_scale`, exposed `pub(crate)` for this reuse rather than re-derived) into SNES
+  pixel space, with trigger/cursor/turbo on left/right/middle mouse buttons. Mirrors
+  `rustysnes-libretro`'s own already-verified `poll_port_input` translation. Portable to wasm on
+  purpose (no `target_arch` gate) — both the pointer API and the `EmuCore` calls are already
+  platform-agnostic, so the hosted demo gets this too. 5 real unit tests cover the pure
+  coordinate-mapping math directly (centered/corner/pillarboxed/off-window cases), not just
+  "compiles."
+
+### Fixed
+
+- **A real, separate finding surfaced while scoping the above**: `docs/frontend.md`'s own "Status"
+  line claimed controller port 1 had "keyboard + gilrs gamepad" input, but `gilrs::Gilrs` is never
+  actually instantiated anywhere in `rustysnes-frontend` — confirmed via `input::gamepad_button`
+  (the gilrs-button-name mapping function) having zero callers. Port 1 is keyboard-only today.
+  Corrected the doc; wiring real gamepad support is a genuinely separate, larger prerequisite
+  (a live `Gilrs` instance + per-frame event polling), not something silently expanded into this
+  fix — it's also what blocks Super Multitap sub-pad 1-3 host input specifically, tracked
+  separately in the UI/UX-parity plan's backlog.
+
 ## [1.19.0] "Afterburner" - 2026-07-15
 
 Fifteenth release of the RustyNES-parity roadmap: an optional PGO/BOLT pipeline for the

crates/rustysnes-frontend/src/app.rs

@@ -1013,12 +1013,17 @@ impl App {
                     // Controller port 2 peripheral selection (`v0.9.0`, Phase 7 niche
                     // peripherals) — same "just re-sync unconditionally, once per real frame"
                     // pattern as cheats/watchpoints above; cheap (one enum-tag write) when
-                    // unchanged. Host-input capture for the non-Gamepad devices (a real mouse
-                    // pointer driving Super Scope aim / Mouse deltas, extra gamepads for
-                    // Multitap sub-pads) is a follow-up frontend task — this wires the CORE's
-                    // protocol correctly but doesn't yet feed it live host input
-                    // (`docs/frontend.md` §Peripherals).
+                    // unchanged.
                     emu.set_port_device(1, config.port2_peripheral.to_core());
+                    // Host-input capture for Mouse/Super Scope (`v1.20.0`, closing the gap the
+                    // comment above used to describe) — Multitap sub-pads still have no host
+                    // input source; see `crate::peripherals`'s own module doc for why.
+                    crate::peripherals::sync(
+                        &active.egui_ctx,
+                        &active.gfx,
+                        &mut emu,
+                        config.port2_peripheral.into(),
+                    );
                     // PC breakpoints (`v0.9.0`, T-81-001 PR B) — same re-sync pattern as above;
                     // a no-op branch in `EmuCore::run_frame` when the list is empty.
                     emu.set_breakpoints(&active.breakpoints);
@@ -1089,6 +1094,16 @@ impl App {
                 #[cfg(feature = "debug-hooks")]
                 crate::watchpoints::sync(&active.watchpoints, &mut emu.system_mut().bus);
                 emu.set_port_device(1, config.port2_peripheral.to_core());
+                // Host-input capture for Mouse/Super Scope (`v1.20.0`) — same "re-sync once per
+                // present" cadence the port-device selection above already uses in this threaded
+                // build; live pointer state is read as often as we redraw, matching how
+                // `active.pad1`'s own keyboard latch feeds the thread.
+                crate::peripherals::sync(
+                    &active.egui_ctx,
+                    &active.gfx,
+                    &mut emu,
+                    config.port2_peripheral.into(),
+                );
                 emu.set_breakpoints(&active.breakpoints);
                 emu.set_voice_mutes(config.audio.voice_mutes);
 

crates/rustysnes-frontend/src/gfx.rs

@@ -867,8 +867,13 @@ impl Gfx {
     /// clip-space position so the 4:3 SNES display fits inside the current surface regardless of
     /// window shape — shared by [`Self::blit`] and [`Self::present`]'s filter passes (`v1.2.0`;
     /// extracted from `blit`'s own inline math, a pure behavior-preserving refactor).
+    ///
+    /// `pub(crate)` since `v1.20.0`: `crate::peripherals` reuses this SAME clip-space fraction to
+    /// map host pointer coordinates into SNES pixel space for Mouse/Super Scope input, rather than
+    /// re-deriving the letterbox math a second time and risking the two implementations drifting
+    /// apart.
     #[allow(clippy::cast_precision_loss)]
-    fn letterbox_scale(&self) -> (f32, f32) {
+    pub(crate) fn letterbox_scale(&self) -> (f32, f32) {
         let win_w = self.config.width.max(1) as f32;
         let win_h = self.config.height.max(1) as f32;
         let win_aspect = win_w / win_h;

crates/rustysnes-frontend/src/lib.rs

@@ -68,6 +68,9 @@ pub mod input;
 #[cfg(all(feature = "netplay", not(target_arch = "wasm32")))]
 pub mod netplay;
 pub(crate) mod pacing;
+// Host-input capture for Mouse/Super Scope (`v1.20.0`) — no target_arch/feature gate, matching
+// `set_port_device`'s own unconditional compilation; see the module's own doc for why.
+pub mod peripherals;
 pub mod rewind;
 pub mod save_states;
 pub mod ui_shell;