Platform support and evidence

The compiler's targets table describes code generation capability, not a release/test promise. Its generated snapshot is checked against the current compiler. Proposed 1.0 platform tiers await owner approval.

Target	Current evidence / boundary	Build or check
x86_64 Linux GNU	Native default gate; AVX2/FMA, glibc 2.33+	make gate
aarch64 Darwin	Published arm64 release; separate native gate	gmake mac-check
aarch64 Linux GNU	Cross-emission; native node gate available	make k8s-gate K8S_ARCH=arm64
x86_64 Linux musl	Static release/program checks when musl is present	make musl, make static
aarch64 Linux musl	Cross-emission and recorded qemu-user runs	--static --target aarch64-unknown-linux-musl
arm64 iOS	Emission only; no recorded iOS execution	SDK/static-library linking; not JIT
wasm32-wasip1	WASI programs run under Node/wasmtime; no threads/FMA	make fetch-wasm, make wasm
wasm32-unknown-unknown	Bare wasm; imports/host glue needed	--target wasm32-unknown-unknown
riscv64 Linux	Parked: LLVM has no tailcc	refused unless --allow-unsupported
nvptx64 NVIDIA	PTX kernel emission; external CUDA driver	--emit ptx
wgsl WebGPU	WGSL kernel emission; external WebGPU driver	--emit wgsl

Use FIB_TARGET_CPU=x86-64-v3 when building x86 binaries to distribute. Unset/host builds can require your build host's newer instructions. Cross-linking requires the target's linker, libraries and sysroot. C and wasm retain their explicit portability limits; enabling --allow-unsupported is not support evidence.