Install Compose in orbs with an existing Docker CLI

[skyfallwastaken]

Summary of the problem

Orb setup skipped Compose installation whenever Docker was already installed, leaving the development environment unusable.

Describe your changes

Check for the Compose plugin as well as Docker before skipping installation. This is the foundation of the heartbeat audit follow-up stack above #1686.

Screenshots / Media

Not applicable: backend-only changes.

[greptile-apps]

Greptile Summary

Updates the orb setup script to verify both the Docker CLI and Docker Compose plugin before skipping Docker installation.

• Allows setup to install Compose when Docker is already present.
• Reuses the existing Docker and Compose installation path.
• Does not include the regression coverage required for changed functionality.

Confidence Score: 4/5

The condition is a small and plausible fix, but the explicit repository testing requirement must be satisfied before merging.

The changed branch addresses the missing-Compose scenario, but no automated check exercises an environment where Docker exists without the Compose plugin.

Files Needing Attention: .agents/setup

Important Files Changed

Filename	Overview
.agents/setup	Expands the Docker installation guard to check Compose availability, but lacks required regression coverage for the new branch.

Prompt To Fix All With AI

### Issue 1
.agents/setup:30
**Missing Setup Regression Test**

This adds setup behavior for the case where Docker exists without the Compose plugin, but the PR includes no regression test or CI coverage for that state. The repository requires tests whenever functionality is added or changed, so this requirement must be satisfied before merging.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "Install Compose when Docker is already p..." | Re-trigger Greptile}