The problem
How it works
He planned the feature with the agent and its read-only Oracle subagent, then used it for a UI prototype, filling in scaffolded functions, refactors, documentation and update-flow simulations, stopping or discarding work that went wrong. He personally researched a titlebar bug, switched to an overlay design and restructured the view model before letting the agent continue.
Results and limitations
He reports about 8 hours over three days and $15.98 in token spend across 16 sessions; the agent was strong on prototypes, well-scoped tasks and cleanup, but repeatedly failed on a layout bug and produced a backend he threw away.
Before you try it
Substantial human coding and review shaped the final code, and the time figure is his own rough estimate. The feature first reached only nightly users, and Amp is a hosted tool without a repository in this directory.
Tools and repositories
No ranked repository is involved. This use case still stands on its own source.
- Tools
- Amp · Sparkle
Try it yourself: Plan and build a feature in small reviewed sessions
Fill the fields to adapt the prompt. Empty fields stay as visible [placeholders].
We are adding [Feature] to [Project]. In this first session, do not write code. Read the relevant parts of [Relevant code area] and produce a plan of small, independently testable steps, with open questions and risks. After I approve, each later session handles one step only: implement it, build, run [Build and test command], and summarize what changed. If an approach fails twice, stop and explain rather than trying more variations. End every session by listing anything obvious you may have missed. Do not commit, push or touch unrelated files; I will review and commit selectively.Understand every change before keeping it, and discard agent code you cannot explain.
Sources
- Vibing a Non-Trivial Ghostty Feature (opens in a new tab)
First-person account · mitchellh.com · Published 11 Oct 2025 · Source checked 9 Nov 2026, 22:21 UTC
What this source supports
- Amp with its Oracle subagent used to build update notifications
- 16 sessions, $15.98 in tokens, about 8 hours over three days
- Agent failed on a titlebar layout bug; backend draft discarded
- Author did manual restructuring and final review