fix(agent): emit external execution lifecycle events

[vowor]

AgentScope-Java Version

2.0.1-SNAPSHOT

Summary

• emit RequireExternalExecutionEvent with the pending ToolUseBlocks when a tool suspends for external execution
• emit ExternalExecutionResultEvent only after supplied tool results pass Core validation and are appended to state
• preserve the originating assistant reply ID across same-instance and persisted-state resume
• prevent AG-UI from publishing the suspended placeholder as TOOL_CALL_RESULT
• finish suspended AG-UI runs with a RunFinishedInterruptOutcome

Root cause

Core registered the external-execution event types but did not emit them from the native streamEvents() lifecycle. The AG-UI adapter therefore handled the coarse suspended ToolResultBlock like a completed tool result and exposed [Awaiting external execution] as a terminal result. CopilotKit interpreted that message as an already-completed frontend tool call and skipped its HITL handler.

Impact

External frontend tools now produce a stable interrupt boundary instead of a terminal placeholder result. Clients can execute the pending tool and resume with the matching result, including after rebuilding the agent from the same persisted (userId, sessionId) state.

Validation

• repository-wide mvn test
• repository-wide mvn spotless:check
• regression coverage for same-instance resume, persisted-state resume, duplicate and mismatched result rejection, exactly-once request/result events, and AG-UI interrupt mapping

Fixes #2024

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[vowor]

Hi @oss-maintainer has been ready for review for a few days. Could you please take a look when you have a chance? Thanks!