Fix double extraction when extract ice is used with from'gh-r'

[alberti42]

Problem

When using extract'!' (or extract'!!') together with from'gh-r', the downloaded archive was extracted twice:

1. First by the inline ziextract call in the gh-r download code
2. Then again by the ∞zinit-extract-hook, which runs at !atclone-pre

On the second pass, the original archive no longer exists (it was deleted after the first extraction). The --auto detection then falls back to the file command, which identifies unrelated files (e.g., .jar files, which are technically zip archives) and attempts to extract them — producing errors and potentially corrupting the plugin directory.

Example error output:

[ziextract] detected a zip archive in the file lib/some-library-1.2.3.jar.
[ziextract] ERROR: the file `lib/some-library-1.2.3.jar' doesn't exist.

The same issue also affected the tarball download path.

Root cause

The bug went unnoticed because extract'!' was typically used with cloned repositories (where only the hook runs), not with from'gh-r' releases (where both the inline call and the hook run).

Fix

Guard the inline ziextract calls in both the gh-r and tarball download paths so they only run when the extract ice is not set. When the ice is set, the ∞zinit-extract-hook handles extraction exclusively, avoiding the duplication.

Documentation

Updated the extract ice description in README.md to document the previously undocumented prefix modifiers:

Syntax	Behavior
extract	Auto-detect and extract archives
extract'!'	Extract and flatten one directory level
extract'!!'	Extract and flatten two directory levels
extract'-'	Extract but keep the archive file
extract'!file.tar.gz'	Extract a specific file (useful for cloned repos containing archives)

[alberti42]

@vladdoster Let me know if you need a minimal repro to test this bug and how it is fixed.

[alberti42]

@vladdoster You had started to look into it. Do you need anything from me?
@pschmitt Any time from your side to get a look and give a first feedback / indication?

Perhaps you could start reproducing the bug?

I find this patch super useful. Because the feature was not documented and broken, I did not know it existed for a long time. So, when I was installing apps/plugins from the GitHub releases, I always had to manually move the files in atclone to flatten the structure. But if you use ! this is not needed at all; it makes zinit ... commands much leaner rather than having to deal with boilerplate code...

[pschmitt]

Would be nice to have zunit tests for these, but other than that lgtm.

[alberti42]

Would be nice to have zunit tests for these, but other than that lgtm.

Yes, indeed. Good idea. I will create some tests.

[alberti42]

Would be nice to have zunit tests for these, but other than that lgtm.

@pschmitt I added the new tests and further improved documentation for the ice extract

If I understood it correctly, there is a bug upstream in markdownlint-cli. I made a commit, d345854, to the Zinit main branch. This is a temporary fix to Zinit CI/CD, and it should be reverted once a fix is found upstream.

I filed an igorshubovych/markdownlint-cli#606.

It passes all tests. I dare to merge this PR. Hopefully no regression of any kind. 🤞