Feature: Support Self-Repository Syntax For Actions

[blink1073]

Pre-submission checks

• I am not reporting a bug (crash, false positive/negative, etc). These must be filed via the bug report template.
• I have looked through both the open and closed issues for a duplicate request.
• I affirm that I have followed the AI policy and that this request constitutes my own words and understanding.

What's the problem this feature will solve?

GitHub Actions now supports a dedicated syntax for sibling actions within a repository (docs). References like uses: my_org/my_repo/actions/foo@v1 can be replaced with uses: $/./actions/foo, avoiding the need to keep the internal references consistent and making it easier to work on one action and test it in another. Currently an action with that syntax fails with:

ERROR collect_inputs: github_actions_models::common: msg="malformed `uses` ref: missing `@<ref>` in $/git-sign"
fatal: no audit was performed
error: failed to load file://./tag-version/action.yml as action
  |
  = help: this typically indicates a bug in zizmor; please report it
  = help: https://github.com/zizmorcore/zizmor/issues/new?template=bug-report.yml
Caused by:
    0: failed to load file://./tag-version/action.yml as action
    1: couldn't turn input into a an appropriate model
    2: data did not match any variant of untagged enum Runs

Describe the solution you'd like

Add support for the new self-reference syntax.

Additional context

No response

[woodruffw]

Thanks @blink1073, I'll look at implementing this tomorrow. If I understand correctly it doesn't support the version ref at all, since it behaves exactly like a local action reference but without needing an explicit checkout?

[blink1073]

That is my understanding as well, "sibling actions and workflows automatically match the ref you are already running".

[nodeselector]

@woodruffw that's correct!

[woodruffw]

I tried this out on zizmor-action, noticed two minor things:

1. uses: $ doesn't work, you have to do uses: $/. This is totally fine, but the failure mode is a hard actions startup failure, which is unfortunate IMO (since I had to go into the workflow tab and find the failure rather than seeing it on the PR's preview).
2. The failure itself looks like it gets rendered as though @name is a GitHub username, producing this funny render:

^ just in case it's helpful @nodeselector 🙂

[woodruffw]

#2249 will add this. Thanks again both!

[blink1073]

Thanks @woodruffw!