Fix CI disk space for Docker image builds

[gwarmstrong]

Summary

• Remove irrelevant files to free disk space on Ubuntu runners
• Add docker builder prune -f between image builds to prevent "no space left on device" during sandbox image load

Summary by CodeRabbit

• Chores
  • Optimized CI/CD build pipeline for improved efficiency and reliability, including refined disk space management and additional builder pruning to reclaim space during image builds.
  • Introduced cache-busting for sandbox image builds to ensure updated build artifacts.

[greptile-apps]

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[coderabbitai]

📝 Walkthrough

Walkthrough

CI workflow and Dockerfile updated: workflow replaces macOS-specific disk cleanup with Linux-focused removals and adds docker builder prune -f steps; Dockerfile.sandbox adds a CACHEBUST build ARG.

Changes

Cohort / File(s)	Summary
Workflow disk cleanup & Docker cache .github/workflows/tests.yml	Renamed cleanup step to target Ubuntu; removed macOS-specific cleanup commands and added Linux removals (dotnet, ghc, boost, AGENT_TOOLSDIRECTORY). Added docker builder prune -f after initial image build and after the Nemo skills image build to prune buildx caches.
Sandbox Dockerfile build cache dockerfiles/Dockerfile.sandbox	Added ARG CACHEBUST=2026-02-12 to enable explicit cache busting during builds; no other functional changes.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Switch to building containers on-the-fly for local runs #969 — Also modifies CI image build workflow and docker builder/cache behavior.

Suggested reviewers

• activatedgeek

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix CI disk space for Docker image builds' directly summarizes the main objective of the pull request, which is to address disk space issues in CI pipelines during Docker image builds.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into main

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch georgea/fix-ci-disk-space

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[greptile-apps]

_{2 files reviewed, 1 comment}

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[greptile-apps]

The CACHEBUST ARG invalidates the entire Docker cache on every build since it's placed early in the Dockerfile. This defeats the purpose of the --cache-from and --cache-to flags in .github/workflows/tests.yml:63-64,82-83.

If this was added only for testing purposes (as suggested by the commit message "to test full uncached CI build"), it should be removed before merging.

If cache invalidation is needed permanently, consider:

1. Moving it later in the Dockerfile (after stable layers)
2. Passing it as a build-arg with a timestamp: --build-arg CACHEBUST=$(date +%s)
3. Removing it entirely if the docker builder prune -f on line 72 of tests.yml already solves the disk space issue

[greptile-apps]

_{1 file reviewed, no comments}

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