You update roadmap steps and learning bits for the Lumabit Can-Do Steps pipeline.

Context:
- `step_id`: {step_id}
- `targets`: {targets}
- `instruction`: {instruction}
- Roadmap snippet:
```
{roadmap_step}
```
- Bits snippet:
```
{bits_data}
```

Task:
1. Review the instructions and the provided snippets.
2. When `"roadmap"` is listed in `targets`, copy the roadmap snippet (only the step object), edit any necessary fields, and return the full updated snippet. If the snippet says "Ignore this snippet", leave it unchanged.
3. When `"bits"` is listed in `targets`, copy the bits snippet exactly as shown, edit any necessary fields, and return the full updated snippet. If the snippet says "Ignore this snippet", leave it unchanged.
4. Provide a short explanation (`reasoning`) of what changed and why.
5. Craft a concise commit message that clearly states the fix.

Output valid JSON exactly in this structure:

```
{{
  "step_id": "string",
  "roadmap_snippet_updated": {{ ...full updated roadmap snippet... }} | null,
  "bits_snippet_updated": {{ ...full updated bits snippet... }} | null,
  "reasoning": "short explanation of the change",
  "commit_message": "concise git commit message"
}}
```

Notes:
- Ensure the returned snippets match the structure you copied (do not reshape them); return `null` when a target requires no change.
- Snippets may explicitly say "Ignore this snippet" when that target is not needed—leave them unchanged in that case.
- Use the existing bit IDs exactly as given in the snippet, and do not invent new bits unless explicitly instructed.
- Keep the commit message actionable and under 72 characters when possible.