## Summary
Stacked on #49109 (PR 1 — `deriveNotebookDiff`). This is PR 3 of the
notebook approval-preview stack: a pure presentational component that
renders the cell-level diff for a proposed notebook create/update, for
use in the assistant approval UI (wired in a later PR).
- `NotebookPreview` — header summary (`"6 cells"` for create, `"+2 −1 ~1
↕1"` for update) + entry list + "Show N more cells" for long notebooks.
- `NotebookPreviewCell` — dispatches per entry tag:
`unchanged`/`removed`/`moved` collapse to a muted badge row; `added`
renders source via `CodeBlock` (with a max-height/expand toggle);
`replaced` renders a `DiffEditor` diff, plus a before → after metadata
line when only `database_identifier`/`time_range` changed (SQL/text
identical).
- `NotebookPreview.utils` — pure helpers (labels, source/metadata
extraction, language mapping, summary formatting), unit tested.
- **Safety property**: cell content only ever renders through
`CodeBlock`/`DiffEditor` (literal source), never through a markdown
renderer — agent-authored text can't trigger image loads or link
navigation before the user approves. Covered by an adversarial test
(``, `[y](evil)`, `<img onerror>` → zero
`img`/`[href]`/`[src]` DOM nodes).
- Adds `'markdown'` as a supported `CodeBlock` language (small, additive
change to `packages/ui-patterns`).
Towards FE-4143
## Test plan
- [x] `pnpm --filter studio test` — NotebookPreview suite (21 tests)
passes
- [x] `pnpm --filter studio exec eslint
components/interfaces/Explorer/NotebookPreview` — clean
- [x] `pnpm --filter studio exec tsc --noEmit` — no new errors
- [x] `pnpm exec prettier --check` — clean
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added notebook previews showing create and update summaries.
* Displayed added, removed, moved, unchanged, and replaced cells with
metadata and source diffs.
* Added expandable previews with truncation and a “Show more cells”
option.
* Added Markdown syntax highlighting to code blocks.
* **Bug Fixes**
* Safely render adversarial agent-authored Markdown as literal content.
* **Tests**
* Added comprehensive coverage for notebook previews, summaries,
metadata, formatting, and truncation.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
