Add X-Accel-Buffering: no Header for SSE Responses

Quick Search Confirmation

I searched existing issues in this repository and did not find a duplicate request for adding X-Accel-Buffering headers to SSE responses.

Expected Behavior

When using the spring-ai-starter-mcp-server-webmvc module to handle Server-Sent Events (SSE), the framework should automatically inject the header X-Accel-Buffering: no into all SSE responses. This ensures proxy servers (e.g., Nginx) disable response buffering, allowing real-time streaming of AI-generated content (e.g., chat completions, streaming predictions) without latency.

Example of Expected Headers:
For an SSE endpoint like /stream, the response should include:

Content-Type: text/event-stream
X-Accel-Buffering: no

Current Behavior

• Missing Header: SSE responses from spring-ai-starter-mcp-server-webmvc do not include X-Accel-Buffering: no.
• Consequence: Proxy servers (e.g., Nginx) buffer SSE responses by default, causing:
  • Delayed delivery of real-time data (e.g., chat messages appear in batches instead of streaming).
  • Inconsistent behavior in AI applications where low latency is critical.

Start in the spring-ai-starter-mcp-server-webmvc SSE response handling described in the issue and inspect how SSE responses are produced. Verify the response headers for an SSE endpoint, then ensure completed behavior includes Content-Type: text/event-stream and X-Accel-Buffering: no without proxy buffering.