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Build mode is where your app comes to life. After planning is complete, the AI switches into build mode and begins writing production-quality SwiftUI code. It works through your app screen by screen, creating and editing files until the project is complete — then hands off to the Simulator for a live preview.

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What the AI does in build mode

The AI uses a set of file tools to read, write, and edit Swift files directly in your project folder: You never need to use these tools yourself — they run automatically as the AI works.

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The agentic tool loop

The AI doesn’t write everything in one shot. It works in a continuous loop:
  1. Decides what to do next — based on the plan, the current file tree, and any previous tool results.
  2. Calls one or more tools — for example, reading a file before editing it, or writing several related files in the same step.
  3. Reviews the results — the tool result (file content, search matches, or build output) comes back and the AI uses it to inform the next step.
  4. Repeats until the task is complete or it needs to ask you something.
You watch this loop unfold in real time in the chat panel. Each tool call appears as a collapsible step — you can expand any step to see exactly what the AI read or wrote.

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The chat panel

The chat panel on the left side of the workspace shows everything happening in your project:
  • Your messages — prompts and follow-up requests you send.
  • AI responses — the AI’s summaries, explanations, and replies.
  • Tool steps — each file operation the AI performs, shown as collapsible entries. Expand a step to see the file path and content.
  • Inline questions — if the AI needs your input mid-build, it pauses and presents questions the same way as in plan mode (see Plan mode).

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Sending follow-up messages

You can send a message at any time — even while the AI is still working. Use follow-up messages to:
  • Request a new screen or feature (“Add a settings screen with a dark mode toggle”)
  • Ask for a design change (“Make the card corners more rounded”)
  • Report something that looks wrong (“The list isn’t sorting by date”)
  • Give overall direction (“Make it feel more minimal”)
The AI picks up your message, finishes any in-progress step, and then addresses your request.
Be specific when requesting changes. “The home screen title should use a larger font and the accent color” is clearer than “make the header look better.”

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How build errors are handled

After writing code, 10x compiles the project and launches it on the Simulator. If the build reports errors, the AI reads the error output and attempts to fix the problems automatically — editing files, correcting imports, or resolving type mismatches — then rebuilds. You’ll see these fix attempts appear as additional tool steps in the chat panel.
If the AI cannot resolve a build error automatically after a few attempts, it will describe the problem in chat and ask for your guidance. This is uncommon but can happen with complex type system issues or missing external dependencies.

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Switching back to plan mode

If you want to rethink the scope or architecture after build mode has started, you can ask the AI to switch back to plan mode. Send a message like “Let’s revisit the plan” and the AI will return to its research and planning role without losing any code that has already been written.