fix(core): fix ReActAgent stream event block end ordering

[jujn]

Description:

Close #1634
Fixes ReActAgent streamEvents block lifecycle ordering so text, thinking, and tool-call end events are emitted at the correct transition points instead of being deferred until MODEL_CALL_END.

Code Changes & Architecture

1. Fixed model-call block lifecycle ordering:

   • Added ModelCallBlockLifecycle to manage active text, thinking, and tool-call blocks within a single model-call stream.
   • Flushes THINKING_BLOCK_END before TEXT_BLOCK_START.
   • Flushes active TEXT_BLOCK_END, THINKING_BLOCK_END, and prior TOOL_CALL_END events before a new TOOL_CALL_START.
   • Flushes any remaining active block ends before MODEL_CALL_END.

2. Preserved concurrency-safe state tracking:

   • Kept AtomicBoolean for text/thinking lifecycle state.
   • Kept ConcurrentHashMap for active tool-call tracking.
   • The fix only changes end-event flush timing, not event payloads or block identity.

3. Extended stream event ordering tests:

   • Added coverage for thinking-to-text transitions.
   • Added coverage for text/thinking-to-tool-call transitions.
   • Added coverage for multiple tool calls.
   • Added coverage for summary model-call ordering.
   • Added coverage to ensure consecutive text chunks do not duplicate start/end events.

4. Event output log before and after repair
   使用如下输入用例测试（Text+Thinking+mult Tool Call）：“请先讲一个简单的冷笑话，再并行查北京、杭州天气。”
   然后这里对输出做了简化，所有 delta 只保留第一个，其它原样输出。

修复前

78b07f10652c4aeeb3788170ef1ce6d2
MODEL_CALL_START

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THINKING_BLOCK_START

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THINKING_BLOCK_DELTA

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TEXT_BLOCK_START

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TEXT_BLOCK_DELTA

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TOOL_CALL_START

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TOOL_CALL_DELTA

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TOOL_CALL_START

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TOOL_CALL_DELTA

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TEXT_BLOCK_END

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THINKING_BLOCK_END

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TOOL_CALL_END

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TOOL_CALL_END

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MODEL_CALL_END

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TOOL_RESULT_START

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TOOL_RESULT_START

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TOOL_RESULT_TEXT_DELTA

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TOOL_RESULT_END

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TOOL_RESULT_TEXT_DELTA

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TOOL_RESULT_END

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MODEL_CALL_START

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THINKING_BLOCK_START

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THINKING_BLOCK_DELTA

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TEXT_BLOCK_START

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TEXT_BLOCK_DELTA

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TEXT_BLOCK_END

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THINKING_BLOCK_END

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MODEL_CALL_END

修复后

944985f3fde04b2e8b9e4fd9f746cc1e
MODEL_CALL_START

fcc2f929327942fa967ddbb2713e87bf
THINKING_BLOCK_START

42d0f4f85c6c47a490ff45603de2b728
THINKING_BLOCK_DELTA

a390f43f3a484ee7b86c125c16dcf063
THINKING_BLOCK_END

1baf71010149409fafcd36cbf256bb97
TEXT_BLOCK_START

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TEXT_BLOCK_DELTA

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TEXT_BLOCK_END

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TOOL_CALL_START

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TOOL_CALL_DELTA

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TOOL_CALL_END

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TOOL_CALL_START

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TOOL_CALL_DELTA

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TOOL_CALL_END

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MODEL_CALL_END

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TOOL_RESULT_START

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TOOL_RESULT_START

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TOOL_RESULT_TEXT_DELTA

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TOOL_RESULT_END

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TOOL_RESULT_TEXT_DELTA

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TOOL_RESULT_END

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MODEL_CALL_START

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THINKING_BLOCK_START

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THINKING_BLOCK_DELTA

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THINKING_BLOCK_END

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TEXT_BLOCK_START

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TEXT_BLOCK_DELTA

c3bb8ec529c34f4e9e7d0d2dafafdfdc
TEXT_BLOCK_END

8a4f58ae9a7543ed8a44692e868be41d
MODEL_CALL_END

Checklist

Please check the following items before code is ready to be reviewed.

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

[Copilot]

Pull request overview

Fixes ReActAgent streaming event lifecycle ordering so block end events (thinking/text/tool-call) are emitted at the correct transition points instead of being deferred until MODEL_CALL_END, addressing #1634.

Changes:

• Introduced a per-model-call lifecycle helper to coordinate start/end flushing for text, thinking, and tool-call blocks during streamEvents.
• Adjusted end-event emission so thinking ends before text begins, and active blocks are flushed before tool-call/model-call boundaries.
• Extended end-to-end tests to assert correct ordering across thinking→text, text/thinking→tool-call, multiple tool calls, and summary model-call flows.

Reviewed changes

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

File	Description
agentscope-core/src/main/java/io/agentscope/core/ReActAgent.java	Adds a model-call-scoped block lifecycle tracker and updates streaming emission to flush block end events at transition points.
agentscope-core/src/test/java/io/agentscope/core/agent/ReActAgentNewLoopReplyTest.java	Adds ordering-focused tests to validate corrected stream event sequencing and prevent regressions.

[codecov]

Codecov Report

❌ Patch coverage is 90.38462% with 5 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...e/src/main/java/io/agentscope/core/ReActAgent.java	90.38%	1 Missing and 4 partials ⚠️

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[AgentScopeJavaBot]

🤖 AI Review

PR #1829 fixes issue #1634: ReActAgent streamEvents streaming event ordering was incorrect. The original implementation deferred THINKING_BLOCK_END, TEXT_BLOCK_END, and TOOL_CALL_END events until MODEL_CALL_END, causing frontend consumers to be unable to correctly distinguish block boundaries. The fix introduces a ModelCallBlockLifecycle inner class that flushes previous block END events at block transition points (thinking→text, any→tool-call, any→model-call-end), ensuring strictly ordered event streams. The change involves +94/-59 lines in ReActAgent.java and a new ReActAgentNewLoopReplyTest.java with comprehensive test coverage. The concurrency strategy (AtomicBoolean + ConcurrentHashMap) remains sound. The code is well-structured and the tests are thorough. No blocking issues found.

[AgentScopeJavaBot]

🤖 AI Review

PR #1829 fixes issue #1634: ReActAgent streamEvents streaming event ordering was incorrect. The original implementation deferred THINKING_BLOCK_END, TEXT_BLOCK_END, and TOOL_CALL_END events until MODEL_CALL_END, causing frontend consumers to be unable to correctly distinguish block boundaries. The fix introduces a ModelCallBlockLifecycle inner class that flushes previous block END events at block transition points (thinking→text, any→tool-call, any→model-call-end), ensuring strictly ordered event streams. The change involves +94/-59 lines in ReActAgent.java and a new ReActAgentNewLoopReplyTest.java with comprehensive test coverage. The concurrency strategy (AtomicBoolean + ConcurrentHashMap) remains sound. The code is well-structured and the tests are thorough. No blocking issues found.