fix(model): disable native structured output for DashScope (#1852)

[zhangliyuangit]

AgentScope-Java Version

main (2.0.0-SNAPSHOT)

Description

Background

When using structured output (ReActAgent.call(msgs, MyClass.class, ctx) or the
JsonNode schema overload) with DashScopeChatModel, the returned
Msg.hasStructuredData() was always false and getStructuredData(...) returned
nothing. The same code works on OpenAIChatModel.

Root cause

DashScopeChatModel.supportsNativeStructuredOutput() returned true, so ReActAgent
took the native structured-output path, which relies on response_format carrying
the JSON Schema. But the DashScope native text-generation protocol
(/api/v1/services/aigc/text-generation/generation) only supports
response_format: {"type":"json_object"} and not {"type":"json_schema"}. The
schema was never honored, the model returned natural-language text,
wrapNativeStructuredResult failed to parse it as JSON (logged a WARN), and no
STRUCTURED_OUTPUT metadata was attached.

Note: simply wiring response_format through (mirroring the OpenAI channel) does
not fix this — DashScope's native endpoint does not accept json_schema, so it
would be ignored or rejected with HTTP 400.

Changes

• supportsNativeStructuredOutput() now returns false, routing structured-output
  calls to the tool-based fallback path (doFallbackStructuredCall), which uses
  Qwen function-calling and returns reliable, schema-conforming results.
  supportsNativeStructuredOutputWithTools() stays consistent since it falls back to
  this method.
• Added Javadoc documenting why native structured output is unsupported on the
  DashScope native protocol (and a pointer not to flip it back without proper
  json_object wiring).
• Added a regression test asserting both flags are false.

How to test

ReActAgent.call(msgs, SomeClass.class, ctx) on a DashScopeChatModel now returns a
Msg with hasStructuredData() == true and the parsed object available via
getStructuredData(...).

Unit test: DashScopeChatModelTest#testNativeStructuredOutputUnsupported.

Checklist

• Code has been formatted with mvn spotless:apply
• All tests are passing (DashScopeChatModelTest: 54 passed)
• Javadoc comments are complete and follow project conventions
• Related documentation has been updated (e.g. links, examples, etc.)
• Code is ready for review

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes structured-output routing for DashScopeChatModel by disabling the native structured-output path (which relies on response_format: json_schema), ensuring ReActAgent uses the tool-based fallback path instead.

Changes:

• Updated DashScopeChatModel.supportsNativeStructuredOutput() to always return false, with added Javadoc explaining the DashScope protocol limitation.
• Added a regression test asserting native structured output (with and without tools) is reported as unsupported.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
agentscope-extensions/agentscope-extensions-model/agentscope-extensions-model-dashscope/src/main/java/io/agentscope/extensions/model/dashscope/DashScopeChatModel.java	Disables native structured output and documents the DashScope response_format limitation.
agentscope-extensions/agentscope-extensions-model/agentscope-extensions-model-dashscope/src/test/java/io/agentscope/extensions/model/dashscope/DashScopeChatModelTest.java	Adds regression coverage for the structured-output capability flags.