Add beta documentation for Python and C++ library docs generation

fern/products/docs/docs.yml

@@ -273,6 +273,10 @@ navigation:
           - page: GraphQL Reference
             path: ./pages/api-references/generate-graphql-ref.mdx
             slug: generate-graphql-ref
+          - page: Library documentation
+            path: ./pages/api-references/generate-library-docs.mdx
+            slug: generate-library-docs
+            hidden: true
       - section: Customization
         skip-slug: true
         contents:

fern/products/docs/pages/api-references/generate-library-docs.mdx

@@ -0,0 +1,183 @@
+---
+title: Generate library documentation
+description: Use Fern Docs to generate documentation for Python and C++ libraries. This beta feature renders classes, methods, and types as an interactive reference.
+availability: beta
+---
+
+<Markdown src="/snippets/agent-directive.mdx"/>
+
+<Warning>
+  Library documentation generation is in beta. The feature and its configuration are subject to change.
+</Warning>
+
+Fern generates library documentation from Python and C++ source code. Point Fern at a Git repository containing your library, and Fern renders classes, methods, types, and modules as an interactive reference.
+
+## Supported languages
+
+| Language | Source format | Status |
+|----------|--------------|--------|
+| Python   | `.py` files with docstrings | Beta |
+| C++      | Header files (`.h`, `.hpp`) with Doxygen-style comments | Beta |
+
+## Configuration
+
+Configure library documentation in your `docs.yml` file using the `libraries` key.
+
+```yaml title="docs.yml"
+libraries:
+  my-lib:
+    input:
+      git: "https://github.com/org/repo"
+      subpath: "src/sdk"               # optional
+    output:
+      path: "./pages/reference"
+    lang: python
+```
+
+### Configuration properties
+
+<ParamField path="lang" type="string" required>
+  The language of the library. Supported values: `python`, `cpp`. Routes to the appropriate documentation generator.
+</ParamField>
+
+<ParamField path="input.git" type="string" required>
+  The Git repository URL containing the library source code. Only `git` input is supported.
+</ParamField>
+
+<ParamField path="input.subpath" type="string">
+  A subdirectory within the repository to use as the root of the library. For example, `"src/sdk"` if the library code lives in a subdirectory.
+</ParamField>
+
+<ParamField path="output.path" type="string" required>
+  The local path where Fern outputs the generated reference pages.
+</ParamField>
+
+<ParamField path="config.doxyfile" type="string">
+  Path to a [Doxyfile](https://www.doxygen.nl/manual/config.html) configuration file. C++ only. The file is read from disk and sent as raw content to the backend.
+</ParamField>
+
+## Examples
+
+<Tabs>
+<Tab title="Python">
+
+```yaml title="docs.yml"
+libraries:
+  plant-sdk:
+    input:
+      git: "https://github.com/my-org/plant-sdk"
+      subpath: "src/plant"
+    output:
+      path: "./pages/plant-reference"
+    lang: python
+```
+
+</Tab>
+<Tab title="C++">
+
+```yaml title="docs.yml"
+libraries:
+  plant-sdk:
+    input:
+      git: "https://github.com/my-org/plant-sdk"
+      subpath: "include"
+    output:
+      path: "./pages/plant-reference"
+    lang: cpp
+    config:
+      doxyfile: "./Doxyfile.txt"
+```
+
+</Tab>
+</Tabs>
+
+### Multiple libraries
+
+To generate documentation for more than one library, add multiple entries under the `libraries` key:
+
+```yaml title="docs.yml"
+libraries:
+  plant-sdk:
+    input:
+      git: "https://github.com/my-org/plant-sdk"
+    output:
+      path: "./pages/plant-reference"
+    lang: python
+  garden-sdk:
+    input:
+      git: "https://github.com/my-org/garden-sdk"
+      subpath: "include"
+    output:
+      path: "./pages/garden-reference"
+    lang: cpp
+    config:
+      doxyfile: "./Doxyfile.txt"
+```
+
+## Generate your library docs
+
+After configuring `docs.yml`, run the following command to generate and preview your documentation:
+
+```bash
+fern docs dev
+```
+
+This starts a local development server at `http://localhost:3000` where you can view the generated library reference.
+
+To publish your documentation, run:
+
+```bash
+fern generate --docs
+```
+
+## Writing effective source comments
+
+Fern uses comments in your source code to generate descriptions for classes, methods, and types.
+
+<Tabs>
+<Tab title="Python">
+
+Use [Google-style docstrings](https://google.github.io/styleguide/pyguide.html#38-comments-and-docstrings) for the best results:
+
+```python
+class PlantClient:
+    """Client for interacting with the Plant API.
+
+    Args:
+        api_key: Your API key for authentication.
+        base_url: The base URL of the Plant API.
+    """
+
+    def get_plant(self, plant_id: str) -> Plant:
+        """Retrieve a plant by its ID.
+
+        Args:
+            plant_id: The unique identifier of the plant.
+
+        Returns:
+            The requested Plant object.
+        """
+```
+
+</Tab>
+<Tab title="C++">
+
+Use [Doxygen-style comments](https://www.doxygen.nl/manual/docblocks.html) for the best results:
+
+```cpp
+/**
+ * @brief Client for interacting with the Plant API.
+ */
+class PlantClient {
+public:
+    /**
+     * @brief Retrieve a plant by its ID.
+     * @param plantId The unique identifier of the plant.
+     * @return The requested Plant object.
+     */
+    Plant getPlant(const std::string& plantId);
+};
+```
+
+</Tab>
+</Tabs>