arc

Arc

The full arc from idea to shipped code.

Arc is a self-contained software development lifecycle for coding agents. It helps move work from early project clarity through ideation, implementation, review, testing, launch readiness, and clean commits.

• Claude Code: install as a plugin and run /arc:* commands.
• Codex: install as a native plugin and invoke workflows with $<skill-name>.
• Cursor: first-class plugin via .cursor-plugin/; install locally or from a team marketplace, then invoke with /<skill-name>.

Arc's canonical product definition and operating boundary live in CONTEXT.md. This README is the user-facing guide.

Workflow

WHY     /arc:vision     - Define goals, boundary, and domain language in CONTEXT.md
          ↓
WHAT    /arc:ideate     - Turn an idea into a validated feature spec
          ↓
DO      /arc:implement  - Plan and build with TDD and verification
        /arc:testing    - Backfill safety-net tests around existing code
        /arc:launch     - Check go-live and shareability basics

REVIEW  /arc:review     - Review a plan, spec, or implementation approach
        /arc:audit      - Verify and audit current codebase health
        /arc:refactor   - Find structural friction and propose refactors
        /arc:improve    - Turn findings into a vetted plan backlog, keep it reconciled

TOOLS   /arc:commit     - Create clean commits, optionally push
        /arc:release    - Version, changelog, verify, and publish packages

using-arc and detail are supporting skills. They keep startup context small and create implementation plans, but they are not normally invoked directly.

What Arc Is For

Arc owns the software development cycle:

• Clarify why the work matters.
• Shape ideas into concrete specs and implementation plans.
• Implement with tests, review checkpoints, and verification.
• Backfill characterization tests before risky changes to old code.
• Audit codebase health when you need a current-state report.
• Prepare a project to be visitable, shareable, and ready for a first real audience.
• Commit work in atomic, readable commits.

Arc deliberately does not own every adjacent specialist practice. Brand identity, visual design systems, dependency upgrade campaigns, deep SEO, AI framework guidance, generated documentation, browser QA, and machine/editor automation are better handled by dedicated tools. Arc may notice those concerns during implementation, review, audit, or launch, but its public workflow stays focused on software delivery.

Install

Claude Code

claude plugin marketplace add howells/arc
claude plugins install arc@howells

This installs the full Arc plugin: skills, slash commands, agents, references, disciplines, templates, scripts, and rules.

Native plugin install (Codex CLI 0.117+):

codex plugin marketplace add howells/arc
codex plugin add arc@howells

This installs Arc into Codex's isolated plugin cache — skills, agents, references, disciplines, templates, scripts, and rules — so it never collides with your other skills. Invoke workflows with $<skill-name>; update with codex plugin marketplace upgrade.

Alternatively, a clone-and-symlink installer links Arc skills into ~/.agents/skills (Codex's user skills directory); see .codex/INSTALL.md. Prefer the native plugin above.

Cursor

Arc is a first-class Cursor plugin (Cursor 2.5+). Local and team installs use the full repo, so skills, commands, agents, references, disciplines, templates, and scripts stay available — the same full-runtime model as Claude Code and Codex. Arc's internal rules/ corpus is not injected as always-on Cursor rules.

# from a checkout
bash .cursor/install.sh

# or clone straight into Cursor's local plugin dir
git clone https://github.com/howells/arc.git ~/.cursor/plugins/local/arc

Reload Cursor (Developer: Reload Window), then invoke /ideate, /implement, /audit, etc. On Teams/Enterprise, import github.com/howells/arc as a team marketplace from the Cursor dashboard. Details: .cursor/INSTALL.md.

Prompt-Only Install

npx skills add howells/arc

This copies SKILL.md prompts to supported agents. It is useful for lightweight guidance, but it does not include Arc's bundled agents, references, disciplines, templates, scripts, or rules. Workflows such as audit, review, implement, refactor, and testing work best with the Claude plugin, native Codex plugin, or Cursor plugin.

Invoking Arc

Claude Code

Use slash commands: