This release of Zig upgrades to LLVM 18.1.7.

This was the primary motivation for tagging the 0.13.0 release.

This release features 8 months of work: changes from 244 different contributors, spread among 1183 commits.
Perhaps most notably, this release debuts I/O as an Interface, but don't sleep on the Language Changes or enhancements to the Compiler, Build System, Linker, Fuzzer, and Toolchain which are also included in this release.

What we did need, however, was a Git server implementation that could run on Cloudflare Workers. It needed to be small, as complete as possible, extensible (notes, LFS), and efficient. So we built one in Zig, and compiled it to Wasm.

Why did we use Zig? Three reasons:

1. The entire git protocol engine is written in pure Zig (no libc), compiled to a ~100KB WASM binary (with room for optimization!). It implements SHA-1, zlib inflate/deflate, delta encoding/decoding, pack parsing, and the full git smart HTTP protocol — all from scratch, with zero external dependencies other than the standard library.

2. Zig gives us manual control over memory allocation which is important in constrained environments like Durable Objects. The Zig Build System lets us easily share code between the WASM runtime (production) and native builds (testing against libgit2 for correctness verification).

3. The WASM module communicates with the JS host via a thin callback interface: 11 host-imported functions for storage operations (host_get_object, host_put_object, etc.) and one for streaming output (host_emit_bytes). The WASM side is fully testable in isolation.

Under the hood, Artifacts also uses R2 (for snapshots) and KV (for tracking auth tokens):