Evaluate the next agent adapter beyond Claude Code, Codex, and Pi

[owainlewis]

Status

Pi support has shipped. This issue now evaluates whether another backend should follow the existing Claude Code, Codex, and Pi adapters.

Goal

Choose whether Push should add another agent backend after the three shipped adapters are stable in real use.

Candidates

• Gemini CLI or another first-party coding agent.
• Aider or another mature open-source coding agent.
• AMP, Cursor, OpenCode, or a similar CLI if it exposes a stable headless contract.

Acceptance criteria

• List candidate CLIs and their session, prompt, permission, final-output, and failure contracts.
• Compare candidates against the shipped Claude Code, Codex, and Pi adapter contracts.
• Rank candidates by reliability, install friction, headless support, debuggability, and user value.
• Open implementation issues only for the chosen adapter or adapters.
• Document why rejected candidates are not next.