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Install Hal CLI

Install the Hal CLI, verify the command is available, and check the AI coding engine prerequisites before running a PRD-native loop.

Last updated: May 9, 2026 · Reviewed by ReScience Lab

Run the first loop Inspect source

Why it matters

Start with a local install you can verify. Hal is a terminal-first CLI, so installation should end with a working `hal version` check before you run a coding loop.

How do you install Hal CLI?

Install Hal by using the Homebrew command shown on this website, then verify the hal command is available before running a coding loop. Hal is a terminal-first CLI, so setup should end with a local command check and a review of current repository installation notes.

Install with Homebrew

Use the install command shown by this site:

brew tap j-yw/tap && brew install --cask hal

After installation, open a new terminal session if your shell needs to refresh its PATH.

Verify the binary

Confirm that the hal command is available before using it in a repository:

hal version

If your installed release supports diagnostics, run:

hal doctor

Use the GitHub README as the source of truth for release-specific installation notes.

Check engine prerequisites

Hal wraps a coding loop around an implementation engine. Make sure you have access to one of the supported agent engines mentioned by this site: Codex, Claude Code, or Pi.

The engine may have its own authentication, subscription, API, IDE, or model requirements. Those costs and limits are separate from Hal.

Initialize a repository

Run Hal inside a repository you can inspect and revert safely:

hal init

Start with a branch and a small task. Do not point a new tool at production code without version control and a review plan.

Next step

Once installation is verified, run a small first loop. Use a narrow requirement, validate the generated stories, and inspect the output before merging.

Verification and review rule

Before adopting Hal, verify the current source repository, install path, release notes, and supported engine behavior. A completed loop is reviewable agent output, not a guarantee that the code is safe to merge.

Use the PRD readiness checker before planning, read the PRD-driven planning feature, and review whether Hal replaces code review before expanding to larger tasks.

FAQ

Short answers before you put this into an agent workflow.

What is the current install command shown by this site?

This site shows the Homebrew command for installing the Hal cask on macOS: brew tap j-yw/tap && brew install --cask hal. Verify the current repository README before production adoption.

Do I need an AI coding agent installed too?

Yes. Hal supplies the workflow loop. You still need access to a supported coding engine such as Codex, Claude Code, or Pi.

What should I run after installing?

Run hal version or hal doctor if available in your installed release, then initialize a low-risk repository with hal init.

Related docs

Keep exploring the pieces of a reviewable coding loop.

Run your first Hal loop

Run a small Hal loop from PRD planning through validation, implementation, and human review without handing over a broad feature.

Review Hal output before merging

Use this checklist to review AI coding loop output from Hal before merging commits, reports, workflow state, or generated code.