Move Cask CI helpers into brew

[p-linnane]

generate-cask-ci-matrix moved into brew in November 2024, and homebrew-cask deleted its cmd/lib/ci_matrix.rb and siblings in January 2025. check.rb and zap_check.rb are what was left behind, and since the tap has no spec suite they have never been tested, typechecked or linted.

This finishes that migration. brew cask-ci provides the info, snapshot, zap-check and check operations the Cask CI workflow needs, with the helpers namespaced under Cask::CI. A follow-up in homebrew-cask deletes the tap copies and repoints the workflow.

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• I did not use AI/LLM to create this PR, or I disclosed the tool/model below and reviewed its output; I did not attribute commits to AI and will answer maintainer questions and review comments myself without AI/LLM.

Claude Code (Opus 5) drafted the move and its 28 tests; I reviewed the diff, confirmed the manual_install check matches the existing idiom in cask/upgrade.rb, verified the generated completions match brew generate-man-completions output, and ran brew lgtm --online.

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[Copilot]

🟢 Approval recommended

The migration preserves the existing Cask CI behaviour while adding focused tests, strict typing and generated integration files.

Pull request overview

Moves Homebrew Cask CI helpers into brew under Cask::CI.

Changes:

• Adds brew cask-ci with four CI operations.
• Adds snapshot comparison and zap-check helpers.
• Adds tests, Sorbet RBI and generated completions.

File summaries

File	Description
Library/Homebrew/dev-cmd/cask-ci.rb	Implements the command dispatcher and CI outputs.
Library/Homebrew/cask/ci/check.rb	Captures and compares system state.
Library/Homebrew/cask/ci/zap_check.rb	Exercises apps and checks zap coverage.
Library/Homebrew/test/dev-cmd/cask-ci_spec.rb	Tests command operations and outputs.
Library/Homebrew/test/cask/ci/check_spec.rb	Tests snapshot comparison behaviour.
Library/Homebrew/test/cask/ci/zap_check_spec.rb	Tests zap matching and reporting.
Library/Homebrew/sorbet/rbi/dsl/homebrew/dev_cmd/cask_ci.rbi	Adds generated command argument types.
completions/bash/brew	Adds Bash completion support.
completions/fish/brew.fish	Adds fish completion support.
completions/zsh/_brew	Adds zsh completion support.

Review details

Files not reviewed (1)

• Library/Homebrew/sorbet/rbi/dsl/homebrew/dev_cmd/cask_ci.rbi: File type not supported

• Files reviewed: 9/10 changed files
• Comments generated: 0
• Review effort level: Balanced

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[bevanjkay]

I'm not sure how many downstream taps actually exercise the scripts, mine is one of them. I wonder if we need to run a deprecation on the removal of the scripts from the tap, or a temporary function stub that prints the migration step or just leave it be?

[p-linnane]

I don't feel strongly about it either way. Just trying to eliminate any brew ruby usage across our repos.

[bevanjkay]

The blast radius seems like it's contained to 9 third-party taps, so I think we can just ahead with the migration cold turkey.

[MikeMcQuaid]

Thanks! ✅ to unblock. Would be nice to try to incorporate this into brew test-bot instead and have that be the default workflow for formula and casks. That'd vastly improve the experience for cask tap maintainers too.