Fastly Compute 2026-08-31

Use these platform rules for the Fastly Compute documentation snapshot dated 2026-08-31. SDK-specific guidance is anchored to JavaScript 3.44.3, Rust 0.13.1, Go 1.9.0, and C++ 0.7.0; the hosted platform has no corresponding customer-pinned runtime version. Apply each language-specific rule only to that SDK.

Runtime and SDK compatibility

• Compile Rust with the wasm32-wasip1 target and a Fastly-compatible compiler satisfying the SDK and dependency requirements; fastly 0.13.1 requires Rust 1.88 or later, and Fastly excludes Rust 1.91.0 and 1.93.0.
• Treat Node.js as JavaScript build tooling, not the deployed runtime; use a maintained Node.js version compatible with locked build dependencies and avoid libraries requiring Node-native runtime bindings.
• Build Go for GOOS=wasip1 and GOARCH=wasm; respect Go SDK 1.9.0's go 1.23.12 declaration and compatible TinyGo configuration instead of assuming the older platform-wide minimum is sufficient.
• Match C++ 0.7.0's prebuilt library to its WASI SDK 33.0 toolchain and C++20 requirements; do not assume this SDK implements ACLs, reusable sandboxes, shielding, or origin mutual TLS.
• Check SDK feature gates before relying on cache hooks: JavaScript requires --enable-http-cache, Go requires -tags=fsthttp_guest_cache, and C++ 0.7.0 lacks the customized readthrough callbacks.

Request and identity boundary

• Authenticate and authorize the normalized host, method, path, tenant, and resource before any protected cache lookup or response; an origin-only authorization check does not protect cache hits.
• Allowlist public