[BUG] ShenyuMcpResponseDecorator completes future on first chunk (truncates multi-chunk bodies)

[Aias00]

• severity: High
• files: shenyu-plugin/shenyu-plugin-mcp-server/src/main/java/org/apache/shenyu/plugin/mcp/server/response/ShenyuMcpResponseDecorator.java:72-78
• description: In writeWith, doOnNext appends each chunk to body and, if !future.isDone(), immediately completes responseFuture with applyResponseTemplate(this.body.toString()) — i.e. with only the first chunk accumulated so far. Subsequent chunks append to body but the future is already done.
• impact: Tool-call results are truncated to the first chunk for any response delivered in more than one DataBuffer.
• suggested_fix: Complete the future only in setComplete() (or use collectList() then complete), not per-chunk.
• confidence: High
• related_existing: none

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Identified during the 2026-08-02 deep re-scan; full list in docs/scan2-2026-08-02/00-consolidated-critical-high.md.

[github-actions]

👋 Hello @yuluo-yx

A new issue has been opened by @Aias00:

• Title: [BUG] ShenyuMcpResponseDecorator completes future on first chunk (truncates multi-chunk bodies)
• Link: [BUG] ShenyuMcpResponseDecorator completes future on first chunk (truncates multi-chunk bodies) #6640

Please review when you have time. Thank you! 🙏

[wy471x]

/assign