Summary

/btw can fail in a Telegram chat with:

401 You have insufficient permissions for this operation.
Missing scopes: api.responses.write

This happens in a setup where the active/default model is canonical openai/gpt-5.5, but authentication is via a ChatGPT/Codex OAuth profile rather than an OpenAI API key.

Environment / Context

• Channel observed: Telegram DM command /btw ...
• Default model: openai/gpt-5.5
• Effective auth: openai-codex:<profile> OAuth
• Normal agent runs in this environment use the Codex harness/runtime path successfully.
• /btw is implemented as a lightweight side-question path separate from the normal run path.

Suspected Bug

/btw appears to bypass the normal selected harness/runtime auth transport and fall into a generic OpenAI Responses call.

That produces an invalid combination:

• model/provider selection: openai/gpt-5.5
• credential: Codex OAuth token
• transport: plain OpenAI /v1/responses

Plain OpenAI Responses correctly rejects that token because it lacks api.responses.write. For Codex-backed OpenAI models, the side question should route through openai-codex / openai-codex-responses or a Codex-harness-native side completion instead.

Important Detail

This should not be fixed only via the PI helper path. The observed lane uses the Codex harness, so the invariant should be higher-level:

/btw must honor the active session's selected harness/auth transport, Codex included.

Expected Behavior

When the active/default model is openai/gpt-* and auth is backed by Codex OAuth, /btw should use the same effective transport/auth semantics as the active session. It should not call plain OpenAI /v1/responses with a Codex OAuth token.

Suggested Fix Shape

• Make /btw resolve model/auth/runtime through the same plan as the active session.
• Preserve /btw's no-tools/lightweight behavior, but do not bypass provider transport selection.
• Add regression coverage for openai/gpt-5.5 + Codex OAuth + Codex harness, asserting /btw does not call plain OpenAI /v1/responses and instead uses the Codex transport or harness-native side completion.