spring-projects / spring-projects/spring-ai

Stateless Async MCP Server with streamable-http returns only the first element from tools with a Flux return

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bug mcp
Dominant language
Java
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Merged PRs (30d)
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Description

Bug description
It only returns the first value from the Flux.

Expected behavior
Return all values.

Minimal Complete Reproducible example

spring:
  ai:
    mcp:
      server:
        type: async
        protocol: stateless
        streamable-http:
          mcp-endpoint: /mcp
public Flux<Object>> getSomething ...

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the stateless async streamable-http MCP server configuration with a tool returning a Flux. Trace the streamable-http handling for that tool and verify completion when all Flux elements, rather than only the first, are returned.

Written by the indexing model from the issue text.

Assessment

Tech stack
java, spring
Domain
api, backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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