chore: import upstream snapshot with attribution

examples/mcp/manager_example/README.md

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+# MCP Manager Example (FastAPI)
+
+This example shows how to use `MCPServerManager` to keep MCP server lifecycle management in a single task inside a FastAPI app with the Streamable HTTP transport.
+
+## Run the MCP server (Streamable HTTP)
+
+```
+uv run python examples/mcp/manager_example/mcp_server.py
+```
+
+The server listens at `http://localhost:8000/mcp` by default.
+
+You can override the host/port with:
+
+```
+export STREAMABLE_HTTP_HOST=127.0.0.1
+export STREAMABLE_HTTP_PORT=8000
+```
+
+This example also configures an inactive MCP server at `http://localhost:8001/mcp` to demonstrate how the manager drops failed
+servers. You can override it with:
+
+```
+export INACTIVE_MCP_SERVER_URL=http://localhost:8001/mcp
+```
+
+## Run the FastAPI app
+
+```
+uv run python examples/mcp/manager_example/app.py
+```
+
+The app listens at `http://127.0.0.1:9001`.
+
+## Run the smoke test
+
+To verify the MCP manager and app integration without calling a model:
+
+```
+uv run python -m examples.mcp.manager_example.smoke_test
+```
+
+The smoke test starts the local MCP server on a temporary port, points both app MCP server settings at that server, and checks `/health`, `/tools`, and `/add`.
+
+## Toggle MCP manager usage
+
+By default, the app uses `MCPServerManager`. To disable it:
+
+```
+export USE_MCP_MANAGER=0
+```
+
+## Try the endpoints
+
+```
+curl http://127.0.0.1:9001/health
+curl http://127.0.0.1:9001/tools
+curl -X POST http://127.0.0.1:9001/add \
+  -H 'Content-Type: application/json' \
+  -d '{"a": 2, "b": 3}'
+```
+
+Reconnect failed MCP servers (manager must be enabled):
+
+```
+curl -X POST http://127.0.0.1:9001/reconnect \
+  -H 'Content-Type: application/json' \
+  -d '{"failed_only": true}'
+```
+
+To use `/run`, set `OPENAI_API_KEY`:
+
+```
+export OPENAI_API_KEY=...
+curl -X POST http://127.0.0.1:9001/run \
+  -H 'Content-Type: application/json' \
+  -d '{"input": "Add 4 and 9."}'
+```