Trigger and scope

Trigger on: XVCL, .xvcl files, VCL transpiler, VCL metaprogramming, #const/#for/#def/#inline in VCL context, writing a VCL script, writing VCL and running it locally, or any Fastly VCL writing task.

Do NOT trigger for: debugging existing .vcl files without XVCL, Fastly API/CLI ops, Fastly Compute, or Terraform — even if they mention VCL.

Writing VCL with XVCL

XVCL is a VCL transpiler that adds metaprogramming to Fastly VCL. Write .xvcl files, compile to .vcl, then test with Falco or deploy to Fastly. All XVCL constructs are resolved at compile time — zero runtime overhead.

Quick Start

# Compile (no install needed with uvx)
uvx xvcl main.xvcl -o main.vcl

# Lint the output
falco lint main.vcl