ci: speed up build

[janishorsts]

It refactors our GitHub Actions CI pipeline to eliminate redundant compilation and bootstrap steps, speed up overall build run times, and make better use of the runner's EarthBuild layer caching.

WARNING: This PR requires the change to "Protect default branch" ruleset.

Metrics

Total time:

• Before: ~24 minutes (3 parallel pipelines compiling standard and next Earth binaries independently, taking ~8 minutes each).
• After: ~13 minutes (1 consolidated compilation phase with shared caching, followed by fast-failing engine bootstrap checks before commencing all the high-level tests).

Reduces total execution time by 10 minutes.

Before

graph TD
    A[Code Commit / PR] --> B[Fast Check: Lint, Unit, Fuzz]
    B --> C[Docker Pipeline]
    B --> D[Podman Pipeline]
    B --> E[Next Pipeline]
    
    subgraph Docker Pipeline
        C --> C_Build["Build Earthly (Docker tag) [~8 min]"]
        C_Build --> C_Tests["Run Docker Test Matrix"]
    end
    subgraph Podman Pipeline
        D --> D_Build["Build Earthly (Podman tag) [~8 min]"]
        D_Build --> D_Tests["Run Podman Test Matrix"]
    end
    subgraph Next Pipeline
        E --> E_Build["Build Earthly (Next tag) [~8 min]"]
        E_Build --> E_Tests["Run Next Test Matrix"]
    end

Loading

After

graph TD
    A[Code Commit / PR] --> B[Fast Check & Build: Lint, Unit, Fuzz, Compile]
    
    subgraph Fast Check & Build Runner
        B --> B_BuildStd["Build Standard Earthly [Shared Layer Cache]"]
        B --> B_BuildNext["Build Next Earthly [Shared Layer Cache]"]
    end
    B_BuildStd --> C[Docker Pipeline]
    B_BuildStd --> D[Podman Pipeline]
    B_BuildNext --> E[Next Pipeline]
    subgraph Docker Pipeline Runner
        C --> C_TestBoot["docker-bootstrap-test [Fast check]"]
        C_TestBoot --> C_Tests["Run Docker Test Matrix"]
    end
    subgraph Podman Pipeline Runner
        D --> D_TestBoot["podman-bootstrap-test [Fast check]"]
        D_TestBoot --> D_Tests["Run Podman Test Matrix"]
    end
    subgraph Next Pipeline Runner
        E --> E_TestBoot["next-bootstrap-test [Fast check]"]
        E_TestBoot --> E_Tests["Run Next Test Matrix"]
    end

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[github-actions]

🎉 Are we earthbuild yet?

Great progress! You've reduced "earthly" occurrences by 142 (2.66%)

📈 Overall Progress

Branch	Total Count
main	5341
This PR	5199
Difference	-142 (2.66%)

---

Keep up the great work migrating from Earthly to Earthbuild! 🚀

💡 Tips for finding more occurrences

Run locally to see detailed breakdown:

./.github/scripts/count-earthly.sh

Note that the goal is not to reach 0.
There is anticipated to be at least some occurences of earthly in the source code due to backwards compatibility with config files and language constructs.

[gemini-code-assist]

Code Review

This pull request updates the GitHub Action setup in .github/actions/stage2-setup/action.yml by hardcoding the string 'docker' instead of using the dynamic inputs.BINARY input for both the artifact name and the TAG environment variable. There are no review comments, so we have no feedback to provide.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.

[janishorsts]

/gemini review

[gemini-code-assist]

Code Review

This pull request replaces the dynamic inputs.BINARY parameter with a hardcoded docker string in both the artifact download name and the image tag suffix within the stage 2 setup action. The reviewer notes that hardcoding docker reduces the action's reusability and flexibility, especially when running podman tests, and suggests using a fallback expression like ${{ inputs.ARTIFACT_SUFFIX || 'docker' }} instead.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.