Phase 1 skeleton: declare crate, add compile_error! wasm32 guard so accidental
inclusion in the web bundle fails at compile time (kickoff spec §1.2 invariant).
Native deps intentionally minimal (just winit, no default features). skia-safe /
accesskit / accesskit_winit deferred to Stage F when RenderBackend is actually
implemented. Reason: current top-tier versions of these crates pull transitive
deps (home 0.5.12, litemap 0.7.5, hashbrown 0.17) that require Rust 1.81+ /
edition2024, but our pinned toolchain is 1.80. Pinning to spec versions
(skia-safe=0.74) also fails since 0.74 was never published. Will revisit when
either the toolchain bumps or upstream stabilizes around an MSRV-1.80 line.
Verified:
- cargo build -p openpencil-shell-native PASS
- cargo test -p openpencil-shell-native PASS (1 test)
- cargo check --target wasm32-unknown-unknown -p openpencil-shell-native
fails with the compile_error! guard text (NOT a winit/skia build error).
