Description

Action responses in --agent mode occasionally include Node.js warnings, debug logging, or other non-JSON text mixed into stdout. This breaks JSON parsing of the response.

Examples observed:

• (node:12345) ExperimentalWarning: ... before the JSON
• Debug log lines interspersed with response data

Setting NODE_NO_WARNINGS=1 reduces but doesn't eliminate the issue.

Impact

Consumers must implement defensive JSON extraction that searches for {...} boundaries in raw output rather than parsing the full stdout:

text = raw_output.strip()
start = text.find("{")
end = text.rfind("}")
if start >= 0 and end > start:
    text = text[start : end + 1]
result = json.loads(text)

Suggested Fix

1. Redirect internal logging to stderr (not stdout) in --agent mode
2. Ensure stdout contains only the structured JSON response
3. Suppress Node.js experimental warnings when --agent flag is present