Add aiohttp support documentation for Python SDK

fern/products/sdks/deep-dives/generated-sdk.mdx

@@ -56,6 +56,7 @@ Your SDK users can configure individual requests using language-specific options
 | Timeouts | Configure request timeouts (default: 30 seconds for C# and PHP, 60 seconds for all other languages) | All languages |
 | [Retries](/sdks/deep-dives/retries-with-backoff) | Configure maximum retries (default: 2 with exponential backoff for 408, 429, and 5xx responses) | All languages except Ruby and Swift |
 | Custom HTTP client | Override the default HTTP client for unsupported environments or custom requirements | TypeScript, Python, Java, PHP, and Swift |
+| [aiohttp transport](/learn/sdks/generators/python/aiohttp-support) | Opt into `aiohttp` as the async HTTP transport to resolve DNS concurrency bottlenecks | Python only |
 | Custom headers | Send additional headers with any request | TypeScript, Java, and Swift |
 | Raw response data | Access response headers alongside parsed data | TypeScript, Python, and Go |
 | Query parameters | Add extra query string parameters | TypeScript and Swift |

fern/products/sdks/generators/python/aiohttp-support.mdx

@@ -0,0 +1,53 @@
+---
+title: aiohttp support
+headline: aiohttp support (Python)
+description: Fern-generated Python SDKs auto-detect aiohttp for async HTTP operations, resolving DNS concurrency issues without requiring code changes.
+---
+
+
+Every Fern-generated Python SDK ships with opt-in support for [aiohttp](https://docs.aiohttp.org/) as an async HTTP transport. When the `aiohttp` optional extra is installed, the generated async client uses it automatically instead of the default `httpx.AsyncClient`.
+
+This matters for SDKs that make many concurrent async API calls: `httpx.AsyncClient` serializes DNS lookups via `asyncio.getaddrinfo` under heavy concurrency, while `aiohttp` uses its own resolver to avoid that bottleneck.
+
+No generator configuration is required. The `[aiohttp]` extra, runtime auto-detection, and CI coverage are generated for every Python SDK.
+
+## Installation
+
+SDK users opt in by installing the `aiohttp` extra alongside your package:
+
+```bash
+pip install your-package[aiohttp]
+```
+
+Or with Poetry:
+
+```bash
+poetry add "your-package[aiohttp]"
+```
+
+If a user passes a custom `httpx_client` to the async client constructor, auto-detection is skipped and the provided client is used as-is.
+
+## Generated dependencies
+
+The generated `pyproject.toml` includes an `[aiohttp]` optional dependency group:
+
+```toml title="pyproject.toml"
+[tool.poetry.extras]
+aiohttp = ["aiohttp", "httpx-aiohttp"]
+```
+
+If you define your own extras via the [`extras`](/sdks/overview/python/configuration#extras) configuration option in `generators.yml`, the built-in `aiohttp` extra is preserved and merged with your custom configuration.
+
+## CI testing
+
+The generated GitHub Actions workflow runs tests in two passes so both transport paths are covered:
+
+1. Standard tests without the aiohttp extra.
+2. Tests marked `@pytest.mark.aiohttp` with the extra installed.
+
+To verify the aiohttp path locally:
+
+```bash
+poetry install --extras aiohttp
+poetry run pytest -m aiohttp
+```

fern/products/sdks/generators/python/configuration.mdx

@@ -94,6 +94,8 @@ Specify additional development dependencies to include in the generated SDK's se
 
 <ParamField path="extras" type="object" default="{}" required={false} toc={true}>
 Define optional dependency groups that users can install with your package using pip extras (e.g., `pip install your-package[extra-name]`).
+
+Custom extras are merged with the built-in [`aiohttp` extra](/learn/sdks/generators/python/aiohttp-support) at generation time, so declaring your own extras won't clobber it.
 </ParamField>
 
 <ParamField path="flat_layout" type="bool" default="false" required={false} toc={true}>

fern/products/sdks/sdks.yml

@@ -71,6 +71,9 @@ navigation:
           - page: Dynamic authentication
             path: ./generators/python/dynamic-authentication.mdx
             slug: dynamic-authentication
+          - page: aiohttp support
+            path: ./generators/python/aiohttp-support.mdx
+            slug: aiohttp-support
           - changelog: ./generators/python/changelog
             slug: changelog
           - link: Customer showcase