feat(coreutils): the rest of the toolbox — grep, find, xargs, sed, tar, gzip, zstd

[raphaelvigee]

The seven utilities a build recipe reaches for that uutils does not carry, so the toolbox covers a real recipe rather than only the easy half of one. Each is the same shape as the applets already in the table — a name, a run fn, golden tests — and each is here for a divergence that bites in practice.

• grep, find, xargs (grep-*, ignore) — BSD find has no -printf, and the two xargs disagree about -r. Built on the crates ripgrep uses, so the matcher is a known quantity rather than a fresh regex engine.
• sed — the divergence that started this. GNU takes an optional -i suffix, BSD requires one, so sed -i 's/a/b/' f edits in place on Linux and eats the next argument as a filename on macOS.
• tar, gzip, zstd — reproducible by construction: no mtimes, no uid/gid, no name ordering left to readdir, compression levels pinned. An archive is usually a build output, so a tar that embeds a timestamp is a target that can never be a cache hit twice.

Why one PR and not three

This replaces #442, #443 and #444's applet halves. They touch the same four files — Cargo.toml, the applet table, a module apiece, COREUTILS.md — and ask the reviewer the same question three times: is this the right crate, and is the behaviour right. The applet set reads better judged in one pass.

#441 shows as "merged" through no merge to master. Consolidating reordered the stack so that PR's old base branch came to contain its head, and GitHub closed it as merged and deleted the branch. The commits are here; nothing reached trunk.

Every layer of the stack builds, lints and passes its unit tests independently.

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The stack

Merge bottom-up, and gh stack sync after each one lands — master is squash-only, so the rebase will conflict and the resolution rule in CLAUDE.md applies.

	PR	What
6	#446	drop the host directories from a target's PATH — breaking
5	#445	the toolbox on by default
4	#440	the template rule and the tmpl applet
3	#453	grep, find, xargs, sed, tar, gzip, zstd
2	#438	the crate, the entry points, the shim directory
1	#451	the runner PATH seam ← base, targets master

Only #451 builds automatically: since #449 a stacked PR is skipped unless it carries ci/force-ci. Every layer was checked locally on its own — cargo build --workspace --all-targets, cargo clippy --workspace --all-targets, and its unit tests — not just at the top of the stack.

🤖 Generated with Claude Code

https://claude.ai/code/session_0181d7hhbYWXT42Z1KQPM29Q