Claude Code and similar coding TUIs are very eager to get into writing code, even before their human baby sitter fully understands the implication of what they are about to build.
The core insight with Anvil is that it is much easier to write high quality code which matches the author's intent after iterating on an external plan with your agent.
Align on the architecture, implementation, and verification strategy in a markdown file, then execution is pretty straightforward.
This is not a new concept, but the user experience within TUI apps for this workflow is pretty shit. Claude creates non-semantic plan names like "aquamarine-owl" that are trapped within a single agent context. Spinning up multiple agents to check on different aspects of a plan is annoying and slow, and managing terminal tabs is pure hell.
So I built anvil, this is a fully open source (MIT license) project.