← Engineering Guides

Terminal-First AI Development

Run AI coding agents from the terminal with explicit planning, approvals, and test loops instead of treating the shell like a magic box.

Level Advanced
Time 25 minutes
Tools covered: Claude Code , OpenAI Codex , Aider
cli terminal agentic-coding planning review sandbox
Updated March 7, 2026

What This Guide Is For

Terminal-first AI development is the right lane when your source of truth is the repo, not the editor UI. The advantage is not aesthetic. It is operational: shell commands, tests, Git, and the full project layout are already in the working loop.

Freshness note: Terminal-agent products evolve quickly. This guide was reviewed against official product docs on March 7, 2026.

Who This Fits and Who Should Skip It

Choose this if you:

  • already work comfortably in the shell
  • want repo-aware multi-file implementation
  • trust diffs and tests more than chat polish

Skip it if you still dislike basic terminal navigation or if your work is mostly inline edits in one file. The editor-first guides are a better on-ramp.

The Current CLI Stack

Claude Code

Claude Code is the strongest fit when you want a repo-aware terminal agent with a clear instruction-file story and strong implementation/review rhythm.

OpenAI Codex

Codex matters when you want continuity across app, editor, CLI, and delegated coding tasks. It works well for teams that want one broader system rather than several disconnected assistants.

Aider as the lighter path

Use Aider when you want a more stripped-down terminal workflow with less product surface area and more explicit control over the interaction loop.

The Right Workflow

  1. start from a clean Git state
  2. define the task, constraints, and verification command
  3. ask for a plan first if the change is non-trivial
  4. approve one bounded implementation slice at a time
  5. run tests or build checks
  6. review the diff before merge

The shell gives you leverage only if you stay disciplined about scope.

When To Use CLI Agents

Use them for:

  • refactors spanning several files
  • debugging with logs and failing tests
  • project setup, wiring, and config changes
  • second-pass review and test-gap detection

Do not use them as a substitute for product decisions, architecture judgment, or release approval.

Model Choices For Terminal Work

Risks and Guardrails

  • The terminal makes autonomy feel more powerful than it is.
  • Fast multi-file edits can create large wrong diffs.
  • Test execution can create false confidence if your acceptance criteria were weak.

Set explicit rules for:

  • destructive commands
  • dependency changes
  • secret handling
  • whether the agent may write outside the repo