API authentication requirements

Ensure all API documentation and code examples include proper authentication headers and clearly explain authentication requirements. As of Langflow v1.5, all API requests require a Langflow API key, even when AUTO_LOGIN is enabled. The only exceptions are MCP endpoints (/v1/mcp, /v1/mcp-projects, /v2/mcp) which don’t require authentication regardless of the AUTO_LOGIN setting.

All curl examples, code snippets, and API documentation should include the x-api-key header:

curl -X POST \
  "http://localhost:7860/api/v1/run/FLOW_ID" \
  -H "Content-Type: application/json" \
  -H "x-api-key: $LANGFLOW_API_KEY" \
  -d '{"input_value": "Hello"}'

When documenting API endpoints, explicitly state authentication requirements and provide guidance on obtaining API keys. Update any legacy examples that assume no authentication is needed, and ensure consistency across all API-related documentation. This prevents user confusion and ensures examples work out of the box with current Langflow versions.