feat: add OpenAI responses wrapper

TASKS.md

@@ -101,7 +101,7 @@ Requirements:
 - Support configurable model and temperature.
 - Implement streaming via the Responses API.
 
-Status: ⏳ Pending
+Status: ✅ Complete
 
 ### Task 2.2 - Response builder
 
@@ -115,4 +115,16 @@ Requirements:
 - Handle OpenAI API errors gracefully (authentication, rate limits, timeouts).
 - Return safe advisory-formatted text responses.
 
+Status: ✅ Complete
+
+### Task 2.3 - Error handling and edge cases for OpenAI integration
+
+Update `src/openai/responses.js` test coverage.
+
+Requirements:
+- Add tests for additional error kinds (timeout, unknown API status, empty response body).
+- Test boundary conditions for maxOutputTokens validation (non-positive floats, non-integers, zero).
+- Mock OpenAI SDK network timeout errors separately from rate-limit errors.
+- Verify that no API keys or secrets are ever leaked in error messages across all tested paths.
+
 Status: ⏳ Pending