Tap a gem to select it: BoardView hit-tests the touch to a grid cell and
draws a bright rim + translucent fill over it; tapping the same cell clears
the selection, tapping another moves it, tapping off-board clears it.
Selection only — no swap (that's P5). The HUD renders the live score and
remaining moves (out of the move limit) in the Lato font on a translucent
card above the grid.
The touch→cell geometry is factored into a pure BoardLayout (no GL/stb
imports) that BoardView composes and P5 will reuse for swap endpoints.
tests/hit_test.sx locks point_to_cell as the exact inverse of cell_frame
(every cell center round-trips; off-board taps reject) — headless because
BoardLayout pulls no C imports. goldens/p4_hud.png captures the scene after
a real idb tap at (201,437)pt: the HUD plus a yellow selection rim on the
red gem at cell (col 4, row 3).
Adopt the modules/ui UIPipeline framework (as the chess reference app does)
and replace the P0 placeholder quad with a BoardView (View protocol, modeled
on chess/board_view.sx):
- background.png fills the screen; an 8x8 cell.png grid is centered in the
safe area; each cell's gem is sampled from gems.png by UV column = gem index
(0=red .. 5=purple).
- Drive it from board.sx seeded with 1337 (the board_init golden's seed), so
the on-screen layout matches that snapshot gem-for-gem.
main.sx now hosts the view via UIPipeline (Metal on iOS, GL on desktop) and
heap-allocates the board/asset state behind pointers (UFCS method calls on a
value-typed global mutate a copy, so mutable state must live behind a pointer
as the reference app does).
Vendor the C deps the UI module's image/font path needs (stb_image,
stb_truetype, kb_text_shape, file_utils); their #include "vendors/..." paths
resolve relative to the project root.
Evidence: ios-sim build links clean; tools/run_tests.sh 11/11 pass; running
app captured at goldens/p4_board.png.
Prove the input path end-to-end. Poll platform events in the frame loop
and, on a mouse_down (UIKit touchesBegan, mapped to an Event in uikit.sx),
toggle the centered quad between orange and green. The toggle marks the
vertex buffer dirty; the next frame re-uploads the active color palette
before drawing. Flip on the press only — a tap also delivers mouse_up
(touchesEnded), so toggling on both would net to no visible change.
goldens/p0_input_before.png (orange quad) and goldens/p0_input_after.png
(green quad) bracket a real tap injected at the device-screen center
(201,437 pt) via `idb ui tap` on the booted iOS 26.0 simulator.
Prove the render path end-to-end: bring up UIKit + Metal (already
scaffolded), clear to a solid blue, and draw one centered orange quad via
the GPU protocol's clear+quad path — an MSL pass-through pipeline plus a
6-vertex (2-triangle) NDC buffer, created lazily once the MTLDevice exists.
Geometry is NDC [-0.5, 0.5]² so the quad is the central 50%x50% of the
drawable regardless of device resolution, keeping the screenshot golden
unambiguous. Background (0.10, 0.20, 0.55), quad (1.0, 0.6, 0.0).
goldens/p0_quad.png is the first screenshot golden, captured from the
booted iOS 26.0 simulator after install + launch.
Stand up build.sx (macos + ios/ios-sim targets, bundle id
co.swipelab.m3te, output sx-out/ios/M3te.app, assets dir) and a minimal
main.sx that brings up the platform (UIKit+Metal on iOS, SDL3+GL on
macOS) and renders a solid-clear frame. Add assets/ and goldens/
directories and a .gitignore for build artifacts.
Modeled on game/build.sx and game/main.sx; modules resolve from the
compiler binary with no -L flag.
