Content-hash caching (opt-in)

Use case: skip an expensive build step when its inputs haven’t changed — explicitly, never by guessing from timestamps.

Demonstrates: content-hash caching · Guide: Caching

Prerequisites: none

Run it

rune build

Expected output

building (cached when VERSION is unchanged)

Run rune build again without changing VERSION and Rune reports the task as cached and skips it. Edit VERSION (or run rune --clear-cache) and it builds again.

How it works

[cache(inputs = ["VERSION"], outputs = ["dist/app"])] fingerprints the declared inputs, the task body, the resolved variables, and the executor. A hit is logged, never silent — caching is opt-in, consistent with Rune’s “always run unless you asked to cache” model.