Supported build targets

Go and operating systems

CI builds and tests every commit on Linux, macOS, and Windows with the two most recent Go releases — .github/workflows/ci.yml is the authoritative matrix. The runtime package is standard-library only, enforced by an import-isolation gate on every build.

htmx versions

The engine pins one htmx version per project and validates every hx-* attribute against that version's surface.

htmx 1.x and 3.x are not supported. A version outside the set fails fast with GHTMX-E0502; a construct the pinned version lacks — newer, or removed and renamed by it — reports GHTMX-E0501 naming the replacement.

What each pin accepts, and how to move a project from htmx 2 to 4, is on the htmx versions page.

WebAssembly (NFR-014)

An application importing the runtime, its generated components, and a first-party router adapter is guaranteed to compile for:

• GOOS=js GOARCH=wasm
• GOOS=wasip1 GOARCH=wasm

The guarantee is enforced on every build: a fixture application (runtime + generated components + the chi adapter) and every included adapter compile for both targets in CI, so a dependency unavailable on a WASM target is caught at the point of introduction.

Scope limits

• Compile-time guarantee only. Runtime behavior on WASM depends on the host: net/http serving is unavailable under js/wasm (browser hosts have no listening sockets), and wasip1 socket support depends on the WASI host. Rendering to any io.Writer works everywhere.
• Adapter matrix. nethttp, chi, echo, gin, and martini compile for both targets. fiber is excluded on both: its fasthttp engine uses raw socket syscalls the WASM ports lack (SOCK_NONBLOCK/SOCK_CLOEXEC on js; ForkLock on wasip1). fiberv3 compiles for js/wasm — its newer fasthttp carries the needed port — but stays excluded on wasip1, where fasthttp's tcplisten is excluded by build constraints. beego compiles for wasip1/wasm but is excluded on js/wasm, where its secure-open and graceful-restart code need syscalls the js port lacks (O_NOFOLLOW, SIGHUP). iris and revel are excluded on both: each pulls a terminal-detection logging dependency (kataras/pio, revel/log15) that does not compile on the WASM ports. The exclusion record is self-honest and per-target — when an upstream gains a port, the matrix test demands the entry be updated.
• Tooling is out of scope. The ghtmx CLI, LSP, and dev server target the native platforms above, not WASM.

Performance envelope

The regeneration gate holds ~100 templates under 1 second, and the render-throughput gate holds allocation counts exactly stable against a recorded baseline (benchmarks/corpus/BASELINE.md).