fix: resolve three bugs in core agent and tool management (#1164 #1165 #1166)

[Fruank4]

Summary

This PR fixes three bugs identified in the core library:

• Bug: StaticLongTermMemoryHook injects memory at end of messages instead of beginning #1164 StaticLongTermMemoryHook injects retrieved memory at the end of the message list instead of the beginning, degrading RAG quality
• Bug: ToolGroupManager.activeGroups is not thread-safe, causing race conditions in concurrent agent scenarios #1165 ToolGroupManager.activeGroups uses a non-thread-safe ArrayList, causing race conditions in concurrent agent scenarios
• Bug: NullPointerException in MessageUtils.extractRecentToolCalls when assistant message has no name #1166 MessageUtils.extractRecentToolCalls calls .equals() on msg.getName() without a null check, throwing NullPointerException when an assistant message has no name

Changes

Fix #1164 — StaticLongTermMemoryHook.java

Swap the insertion order so the memory SYSTEM message is prepended before the input messages:

// Before
enhancedMessages.addAll(inputMessages);
enhancedMessages.add(memoryMsg);           // memory appended at end

// After
enhancedMessages.add(memoryMsg);           // memory at beginning
enhancedMessages.addAll(inputMessages);

Fix #1165 — ToolGroupManager.java

Replace the non-thread-safe ArrayList with CopyOnWriteArrayList and update setActiveGroups() / copyTo() to mutate in-place rather than reassign the field:

// Before
private List<String> activeGroups = new ArrayList<>();
// ...
this.activeGroups = new ArrayList<>(activeGroups);   // unsafe reassignment
target.activeGroups = new ArrayList<>(this.activeGroups);

// After
private final List<String> activeGroups = new CopyOnWriteArrayList<>();
// ...
this.activeGroups.clear();
this.activeGroups.addAll(activeGroups);
target.activeGroups.clear();
target.activeGroups.addAll(this.activeGroups);

Fix #1166 — MessageUtils.java

Replace msg.getName().equals(agentName) with Objects.equals() to safely handle null names:

// Before
if (msg.getRole() == MsgRole.ASSISTANT && msg.getName().equals(agentName)) {

// After
if (msg.getRole() == MsgRole.ASSISTANT && Objects.equals(msg.getName(), agentName)) {

Test plan

• Existing unit tests pass (mvn test -pl agentscope-core)
• Verify RAG memory context appears before user query in message list
• Verify no ConcurrentModificationException when multiple agents modify tool groups concurrently
• Verify no NullPointerException when assistant messages without names are present in memory

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ain/java/io/agentscope/core/util/MessageUtils.java	0.00%	0 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

[Fruank4]

三个问题：空指针，并发安全，记忆反序

[Fruank4]

给孩子过了吧 呜呜呜

[LearningGp]

lichuang34 这个账号没有签署 CLA，要不用Fruank4这个账号提交下后两个commit

[Fruank4]

CLA验证了