Add --show-tester-messages flag to display tester agent output in a2a tests

[Copilot]

Display tester agent messages in agent-to-agent test logs, controlled by a new global flag.

Agent-to-agent tests using OpenAI only showed responses from the Voiceflow agent under test, not messages generated by the tester agent. This made it difficult to understand how the tester agent generates its messages based on goal and persona.

Changes

• Added --show-tester-messages global flag (default: true)

  • Controls visibility of tester agent messages in both OpenAI and Voiceflow agent-to-agent tests
  • No short flag to avoid CLI convention conflicts

• Updated AgentTestRunner (OpenAI tester)

  • Logs tester responses: "Tester agent message: <message>"
  • Optimized to trim response string once instead of twice

• Updated VoiceflowAgentTestRunner (Voiceflow tester)

  • Applies same flag for consistent behavior
  • Logs: "Tester agent says: <message>"

• Updated server mode (cmd/server.go)

  • Explicitly sets ShowTesterMessages = true when server starts for better observability in API-based test execution

Usage

# Tester messages shown by default
voiceflow test execute suite.yaml

# Disable for less verbose output
voiceflow test execute suite.yaml --show-tester-messages=false

# Server mode automatically enables tester messages
voiceflow server

Related to agent-to-agent testing improvements and test observability.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Output the message by the tester agent (a2a)</issue_title>
<issue_description>### Is your feature request related to a problem? Please describe.

Currently when we run agent-to-agent tests using OpenAI. We only see the responses from the VoiceFlow agent that we are testing. Not the messages sent by the Tester agent.

Describe the solution you'd like

Output the messages in the logs generated by the OpenAI tester agent. Perhaps add a global CLI argument to enable this.

Describe alternatives you've considered

No alternative to be found

Search

• I did search for other open and closed issues before opening this.

Code of Conduct

• I agree to follow this project's Code of Conduct

Additional context

I believe having this is essential to see how the Tester agent generates its messages based on its goal and persona. </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Output the message by the tester agent (a2a) #52

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[xavidop]

@copilot set ShowTesterMessages when teh server mode starts

[Copilot]

@copilot set ShowTesterMessages when teh server mode starts

Done in d36c242. The server mode now explicitly sets ShowTesterMessages = true for better observability when running agent-to-agent tests through the API.