fix(session): Automatically detect and remove dangling tool calls whe…

[liuxh613]

#871

Describe the bug
When restoring Agent state from a persistent session (such as a database), if the Memory contains incomplete tool calls (ToolUseBlock without a corresponding ToolResultBlock), it causes the following error:
java.lang.IllegalStateException: Cannot add messages without tool results when pending tool calls exist.
Pending IDs: [call_ba1efbfa083f4323adb4f9]

To Reproduce
Steps to reproduce the behavior:

You code
How to execute
See error
Expected behavior
The ReActAgent.loadFrom() method can include automatic cleanup logic.

Error messages
2026-03-05 12:22:57.040 INFO [] io.agentscope.core.tool.Toolkit Line:239 - Registered tool 'context_reload' in group 'ungrouped'
2026-03-05 12:22:57.040 INFO [] io.agentscope.core.memory.autocontext.AutoContextHook Line:185 - AutoContextMemory integration completed for agent: ReActAgent
Error during execution: Cannot add messages without tool results when pending tool calls exist. Pending IDs: [call_ba1efbfa083f4323adb4f9]
java.lang.IllegalStateException: Cannot add messages without tool results when pending tool calls exist. Pending IDs: [call_ba1efbfa083f4323adb4f9]
at io.agentscope.core.ReActAgent.validateAndAddToolResults(ReActAgent.java:335)
at io.agentscope.core.ReActAgent.doCall(ReActAgent.java:256)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:133)
at io.agentscope.core.tracing.TracerRegistry$1.lambda$onNext$0(TracerRegistry.java:92)
at io.opentelemetry.context.Context.lambda$wrapSupplier$8(Context.java:344)
at io.agentscope.core.tracing.telemetry.TelemetryTracer.runWithContext(TelemetryTracer.java:226)
at io.agentscope.core.tracing.TracerRegistry$1.onNext(TracerRegistry.java:89)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onNext(FluxHide.java:137)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:130)
at io.agentscope.core.tracing.TracerRegistry$1.lambda$onNext$0(TracerRegistry.java:92)
at io.opentelemetry.context.Context.lambda$wrapSupplier$8(Context.java:344)
at io.agentscope.core.tracing.telemetry.TelemetryTracer.runWithContext(TelemetryTracer.java:226)
at io.agentscope.core.tracing.TracerRegistry$1.onNext(TracerRegistry.java:89)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onNext(FluxHide.java:137)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondComplete(MonoFlatMap.java:246)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:307)
at io.agentscope.core.tracing.TracerRegistry$1.lambda$onNext$0(TracerRegistry.java:92)
at io.opentelemetry.context.Context.lambda$wrapSupplier$8(Context.java:344)
at io.agentscope.core.tracing.telemetry.TelemetryTracer.runWithContext(TelemetryTracer.java:226)
at io.agentscope.core.tracing.TracerRegistry$1.onNext(TracerRegistry.java:89)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2565)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onSubscribe(MonoFlatMap.java:293)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:75)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:166)
at io.agentscope.core.tracing.TracerRegistry$1.lambda$onNext$0(TracerRegistry.java:92)
at io.opentelemetry.context.Context.lambda$wrapSupplier$8(Context.java:344)
at io.agentscope.core.tracing.telemetry.TelemetryTracer.runWithContext(TelemetryTracer.java:226)
at io.agentscope.core.tracing.TracerRegistry$1.onNext(TracerRegistry.java:89)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onNext(FluxHide.java:137)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondComplete(MonoFlatMap.java:246)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:307)
at io.agentscope.core.tracing.TracerRegistry$1.lambda$onNext$0(TracerRegistry.java:92)
at io.opentelemetry.context.Context.lambda$wrapSupplier$8(Context.java:344)
at io.agentscope.core.tracing.telemetry.TelemetryTracer.runWithContext(TelemetryTracer.java:226)
at io.agentscope.core.tracing.TracerRegistry$1.onNext(TracerRegistry.java:89)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2565)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onSubscribe(MonoFlatMap.java:293)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:75)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:166)
at io.agentscope.core.tracing.TracerRegistry$1.lambda$onNext$0(TracerRegistry.java:92)
at io.opentelemetry.context.Context.lambda$wrapSupplier$8(Context.java:344)
at io.agentscope.core.tracing.telemetry.TelemetryTracer.runWithContext(TelemetryTracer.java:226)
at io.agentscope.core.tracing.TracerRegistry$1.onNext(TracerRegistry.java:89)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onNext(FluxHide.java:137)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2565)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.request(FluxHide.java:152)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:195)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.request(FluxHide.java:152)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:195)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.request(FluxHide.java:152)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:172)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.request(FluxHide.java:152)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:195)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.request(FluxHide.java:152)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:195)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2361)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onSubscribe(FluxOnErrorResume.java:75)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:118)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onSubscribe(FluxHide.java:123)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:118)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onSubscribe(FluxHide.java:123)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onSubscribe(FluxHide.java:123)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:118)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onSubscribe(FluxHide.java:123)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:118)
at io.agentscope.core.tracing.TracerRegistry$1.onSubscribe(TracerRegistry.java:83)
at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onSubscribe(FluxHide.java:123)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:75)
at reactor.core.publisher.MonoDeferContextual.subscribe(MonoDeferContextual.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:75)
at reactor.core.publisher.MonoUsing.subscribe(MonoUsing.java:109)
at reactor.core.publisher.Mono.subscribe(Mono.java:4569)
at reactor.core.publisher.Mono.block(Mono.java:1772)
at io.agentscope.examples.advanced.DaMengRAGFlowStudioExample.main(DaMengRAGFlowStudioExample.java:318)
Suppressed: java.lang.Exception: #block terminated with an error
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:104)
at reactor.core.publisher.Mono.block(Mono.java:1773)
... 1 more

Saving final session...
Closing resources...
2026-03-05 12:22:57.116 INFO [] com.zaxxer.hikari.HikariDataSource Line:349 - HikariPool-1 - Shutdown initiated...
2026-03-05 12:22:57.118 INFO [] com.zaxxer.hikari.HikariDataSource Line:351 - HikariPool-1 - Shutdown completed.
Shutting down Studio...
✓ Done

2026-03-05 12:22:57.120 INFO [] io.agentscope.core.studio.StudioWebSocketClient Line:154 - Socket.IO disconnected from /python namespace
2026-03-05 12:23:57.137 INFO [] io.agentscope.core.model.transport.HttpTransportFactory Line:185 - Shutting down 1 managed HttpTransport(s)

Environment (please complete the following information):

AgentScope-Java Version: 1.0.10-SNAPSHOT
Java Version: 21
OS: windows11
Additional context
Add any other context about the problem here.

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[codecov]

Codecov Report

❌ Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...e/src/main/java/io/agentscope/core/ReActAgent.java	81.81%	0 Missing and 2 partials ⚠️

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