fix(agui): Fix duplicate TextMessageEnd emission (#562)

[xingmengxian]

Background: Fix Duplicate AguiEvent.TextMessageEnd Issue

Problem Description

When using AGUI protocol to request a ReActAgent with SKILL and TOOL capabilities, the AguiAgentAdapter was emitting duplicate AguiEvent.TextMessageEnd events, causing incorrect event closure in the AGUI event stream.

Root Cause

The issue occurs in the convertEvent method of AguiAgentAdapter when processing REASONING events that contain both TextBlock and ToolUseBlock content blocks:

1. First emission path: When processing a ToolUseBlock ,checks if there's an active text message and attempts to end it before starting the tool call (lines 162-169).

2. Second emission path: When processing a TextBlock in the last event (event.isLast() == true), the code emits TextMessageEnd to close the text message (lines 152-158).

3. The bug: If a message contains both text content and tool usage, and the text block is processed as the last event, the TextMessageEnd is emitted. However, when the subsequent ToolUseBlock is processed, the code doesn't check if the message has already been ended, leading to a duplicate TextMessageEnd event.

Impact

• Issue: #562 - AGUI方式下请求使用Skill的ReActAgent，返回的AguiEvent存在闭合错误
• Version affected: 1.0.8-SNAPSHOT
• Symptoms:
  • Duplicate TextMessageEnd events in the AGUI event stream
  • Incorrect event closure state
  • Potential issues with AGUI clients expecting proper event sequencing

Solution

Added a guard check using state.hasEndedMessage(messageId) before emitting TextMessageEnd events. This ensures that:

1. The message end event is only emitted once per message
2. The state tracking correctly reflects whether a message has been closed
3. The event stream maintains proper sequencing and closure semantics

Code Changes

The fix adds a conditional check before emitting TextMessageEnd:

if (!state.hasEndedMessage(messageId)) {
    events.add(
        new AguiEvent.TextMessageEnd(
            state.threadId, state.runId, messageId));
    state.endMessage(messageId);
}

This prevents duplicate emissions while maintaining the existing logic for properly closing messages when tool calls are encountered.

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