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MantleMantle docs

Build apps from an MCP client

Claude Code or Claude Desktop can build a Mantle mini-app for you, end to end, over MCP.

A mini-app is a small React (TSX) app that Mantle bundles and runs in a sandboxed frame under Apps. It reaches your data only through the tools you allow it, and it can keep its own small SQLite database.

Before you start

Claude is connected to your Mantle (Connect Claude over MCP).

Ask Claude

Tell Claude what you want, for example:

Build me a Mantle app that lists my open tasks by due date. Read the app authoring guide first.

Claude then works through these tools:

Tool What it does
app_authoring_guide Reads the rules: allowed imports, styling, the @host bridge, data access
app_create Makes the app and returns its id
app_source_set or app_file_write Uploads the source, whole or one file at a time
app_tools_set Lists the tools the app may call, for example task_list
app_build, then app_publish Compiles the draft (every error comes back with file and line), then makes the green build live

Every edit lands in the draft. The published app does not change until app_publish.

Check it worked

Open Apps in Jackdaw and pick the app. The preview shows the draft build. After publishing, the live app shows the same.

If it fails

  • The build fails: Claude reads the errors from app_build, fixes the file and builds again. A failed build never replaces the last good one.
  • The app shows no data: the tool it calls is missing from app_tools_set. The host refuses any tool not on that list.

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