# impeccable skill-v4.2.0 — Skill 4.2.0

- Product: impeccable (https://whatsnew.fyi/product/impeccable)
- Vendor: impeccable
- Date: 2026-09-04
- Version: skill-v4.2.0
- Original notes: https://github.com/pbakaus/impeccable/releases/tag/skill-v4.2.0
- Permalink: https://whatsnew.fyi/product/impeccable/releases/skill-v4.2.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Ship a small launcher that finds or downloads one static binary for your platform on first run, with a .cmd twin for Windows shells without sh
- **changed** — Design hook now runs in 10.6 ms instead of 46.9 ms on the same corpus and machine
- **changed** — CLI scan of 110 files finishes in 132 ms instead of 282 ms
- **changed** — Static and URL scans, live overlay, Chrome extension, and site now execute the same compiled rules
- **changed** — Live mode loader now clears variants the moment they mount instead of staying painted over them until a refresh
- **changed** — Discard now restores every wrapper of a mapped element

- **No runtime to install.** The skill ships a small launcher that finds or downloads one static binary for your platform on first run. Windows gets a `.cmd` twin for shells without `sh`. Nothing Impeccable does needs Node, npm, or a package install any more.

- **The hook stops taxing every edit.** On the same corpus and machine, the design hook runs in 10.6 ms where the Node script took 46.9 ms, and a CLI scan of 110 files finishes in 132 ms instead of 282 ms. The URL scan is unchanged, because headless Chrome is the whole cost there.

- **One rule engine everywhere.** The static and URL scans, the live overlay, the Chrome extension, and the site all execute the same compiled rules, so a fix lands in every surface at once. The rule core is Apache-2.0 like the rest of the project, and a downstream package can add its own rules without forking.

- **Behavior is pinned, not re-imagined.** The port replays 830 recorded command invocations and 16,058 recorded function calls against the binary and compares byte for byte, with every reviewed exception listed in the repository.

- **Live mode hands off reliably.** When variants land in one HMR batch, the loader now clears the moment they mount instead of staying painted over them until a refresh, and a discard restores every wrapper of a mapped element.