test: keep Stage 1 bare code replies

[lalalune]

Summary

• add a Stage-1 runtime regression test for gemma-style bare Python code replies
• prove the runtime keeps the code verbatim instead of replacing it with the generic fallback apology
• assert the path uses only the Stage-1 model call with no regeneration

Fixes #11504

Verification

• bun run --cwd packages/core test -- src/__tests__/message-runtime-stage1.test.ts
• bun run --cwd packages/core typecheck
• bun run --cwd packages/core lint

Evidence Notes

• N/A screenshots/video: runtime test coverage only; no UI surface changed.
• N/A live LLM trajectory: this is a deterministic regression test for the Stage-1 handling seam; no prompt/model behavior was changed in production code.
• N/A DB artifacts: no persistence or migrations changed.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: b8266873-47a5-49d4-bc15-340e209078e1

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/11504-stage1-bare-code

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[lalalune]

Closing this duplicate draft: #11553 now carries the fuller #11504 fix and closes the issue.