# Develop an extension from an existing example

Start with the smallest example that covers your extension. Each directory is an
independent Python package using the public `deerflow-extension-api` contract.

| Start here                                                       | What it demonstrates                                                                                                           |
| ---------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------ |
| [Extension example](deerflow-extension-example/README.md)        | Middleware, task lifecycle, model observations, services, and HTTP routes. Start here for backend extensions.                  |
| [Conversation bookmarks](deerflow-extension-bookmarks/README.md) | A browser page, conversation action, backend actions, packaged resources, and a model tool. Start here for full-stack plugins. |
| [Agent teams](deerflow-extension-agent-teams/README.md)          | Full Agent orchestration. Use this after the basic contribution and lifecycle patterns are familiar.                           |

Additional examples cover [text-list classification](deerflow-extension-jev-classify/README.md),
[context pruning](deerflow-extension-jev-context/README.md),
[advisory screening of fetched content](deerflow-extension-jev-screening/README.md), and
[sectioned long-form report writing](deerflow-extension-report-sections/README.md).

## Edit, test, check, then install

1. Copy the selected example outside the DeerFlow checkout. Rename its Python
   package, distribution and `deerflow.extensions` entry point. For a full-stack
   plugin, also choose its own namespace and browser module name.
2. Follow the example's README to configure its dependencies and run its tests.
   Keep package behavior tests alongside the extension. For a bundled example
   with a `tests/` directory, CI installs the package with its `dev` extra next
   to this checkout's `deerflow-extension-api`, then runs `pytest`, `ruff check`
   and `ruff format --check`.
3. From the DeerFlow checkout root, prepare the backend environment with
   `make -C backend install`, then check the package:

   ```bash
   uv run --project backend --no-sync python scripts/check_extension.py /absolute/path/to/your-extension
   ```

   To try the checker on an unchanged example:

   ```bash
   uv run --project backend --no-sync python scripts/check_extension.py examples/deerflow-extension-bookmarks
   ```

4. Follow that example's deployment and try-it instructions. Restart Gateway,
   refresh the browser when applicable, and exercise the installed feature.
   Use `make extension-upgrade SOURCE=/absolute/path/to/your-extension` to apply
   later source edits: local installs are snapshots.

## What the checker covers

The script builds a wheel in a temporary directory, checks exactly one extension
entry point and its packaged Python module, parses packaged Python syntax, and
checks that the API dependency range accepts this checkout's contract version.
It validates conventional `ui_manifest.json` resources with the same validator
used by Gateway, including detecting manifests left out of the wheel in flat or
`src/` layouts. A custom manifest filename needs an explicit wheel-relative path:

```bash
uv run --project backend --no-sync python scripts/check_extension.py /absolute/path/to/your-extension --manifest your_package/resources.json
```

The build executes the package's build backend, so check trusted sources. The
checker does not import the extension, call `install()`, install the extension, or
change deployment configuration. Registration/configuration behavior and the
`@extension` version marker are verified when loading the plugin; continue to run
the package tests and the installed feature after packaging checks pass.