Fix a failing build with Fix mode

The agent's repair loop is easiest to understand when you break something yourself first.

1. Break the build

Open any Vite + React project. In src/App.tsx add:

const count: number = "three";

Save with Ctrl/Cmd+S. Monaco underlines the line immediately, but the authoritative check is the sandbox.

2. Run the real type-check

Logs panel → Run command → typecheck. The output is the real tsc result:

src/App.tsx(4,7): error TS2322: Type 'string' is not assignable to type 'number'.

3. Hand it to Fix mode

Switch the agent to Fix and paste the error verbatim. Fix mode uses the same tools as Build with a repair-oriented prompt. Watch the stages:

• loading_context reads src/App.tsx because the error names it.
• planning proposes a one-line change.
• working edits the file (a snapshot is created first).
• validating runs typecheck again and gets a clean result.

4. See the bound

If a fix introduces a new error, the agent enters repairing and tries again, at most twice. After that the run ends as failed with the last error shown, and the snapshot lets you revert. This is deliberate: an unbounded loop would burn your quota on a problem that needs a human.

5. Review

Open the run in History and inspect the diff. It should touch one line. If the agent did more than you asked, that is a sign the prompt was too open; see Prompting.