[Zhoujie628]

Problem

AgentAuthManager.loadFromFile() uses new File(path) which does not understand the classpath: prefix. When SpringWorkbenchExecutor passes classpath:spn_agent_credentials.json, the file is silently not found and no credentials are loaded.

Symptom: PROTOCOL logs show A2A-Extensions header but no Authorization header. No [Auth] log output at all.

Root Cause

SpringWorkbenchExecutor.resolveCredentialsPath() returns classpath:spn_agent_credentials.json when the resource exists on classpath. But AgentAuthManager.loadFromFile() does:

File file = new File(path);
if (!file.exists()) {
    return new HashMap<>();  // silent return, no log
}

Fix

1. Detect classpath: prefix and use ClassLoader.getResourceAsStream()
2. Add warn logs for missing files (previously silent)

Changes (2 files)

• AgentAuthManager.java: Add classpath: support in loadFromFile()
• AgentAuthManagerTest.java: Add 2 test cases for classpath: prefix

Testing

• mvn test -pl workflow-engine -Dtest=AgentAuthManagerTest passes (4 tests)
• Verified [Auth] Loaded credentials for N agent(s) from classpath:... log appears

Closes #18