Built on CLI Agents
Twill doesn’t reinvent the wheel—it orchestrates existing CLI coding agents like Claude Code and OpenCode. This is intentional:- Tools developers already use: CLI agents are the same tools you use daily in your terminal. There’s no new interface to learn, and the code they produce follows the same patterns you’d write yourself.
- Optimized by AI labs: Model providers like Anthropic, OpenAI, and Google train models to use their toolchains effectively. By delegating work to these CLIs, Twill can take advantage of that optimization.
Sub-Agent Architecture
Twill uses specialized sub-agents for different phases of a task. Not every task uses every sub-agent, but the overall workflow looks like this:Research & Planning (optional)
If you request a plan (or the task is ambiguous), the Planning Agent explores
the repo, asks clarifying questions, and produces an implementation plan for
you to approve.See Research & Planning.
Implementation
The main coding agent implements the changes and adapts when reality doesn’t
match assumptions (for example, existing patterns or unexpected edge cases).
Dev Environment Setup (when needed)
If the sandbox environment is missing or unhealthy, Twill delegates to a Dev
Environment Agent to create or fix the bootstrap script, ports, and required
environment variables.See Automatic Environment Setup and Repository Environments.
Verification + Review
Twill runs mechanical checks (tests, linting, type checking, builds) and
delegates a focused review to a Code Reviewer Agent to catch logic issues and
missed requirements.See Verification.
Self-Verification in Sandboxes
What makes this verification loop actually work is that Twill runs your entire project inside an isolated sandbox environment. The agent doesn’t just write code — it:- Starts your dev server using your entrypoint script
- Runs your test suite to catch regressions
- Manually tests UI changes using browser automation
- Calls API endpoints to verify backend changes
- Inspects logs to confirm services are healthy