[FEATURE]: NotebookEdit tool for Jupyter notebook cell-level editing #20487

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Describe the enhancement you want to request

Problem

OpenCode has no Jupyter-aware tool. Agents working on data science, ML, or research codebases must use write_file to overwrite entire .ipynb files. This approach:

• Destroys cell metadata, execution counts, and cell outputs that are not part of the agent's edit
• Makes diffs unreadable (entire file replaced vs. one cell changed)
• Requires the agent to hold the full notebook in context just to change one cell
• Breaks notebook-aware tools downstream (nbconvert, nbformat validation, CI)

claw-code implements a NotebookEdit tool supporting replace, insert, and delete operations at the individual cell level.

Proposed solution

// packages/opencode/src/tool/notebook-edit.ts

export const NotebookEditTool = Tool.define({
  name: "NotebookEdit",
  description: "Replace, insert, or delete a single cell in a Jupyter notebook (.ipynb) without overwriting the entire file.",
  parameters: z.object({
    notebook_path: z.string(),
    cell_id: z.string().optional(),       // target cell (by id or index)
    new_source: z.string().optional(),    // cell content for replace/insert
    cell_type: z.enum(["code", "markdown"]).optional(),
    edit_mode: z.enum(["replace", "insert", "delete"]).default("replace")
  }),
  execute: async (input) => {
    const nb = await readNotebook(input.notebook_path)
    const result = applyNotebookEdit(nb, input)
    await writeNotebook(input.notebook_path, result.notebook)
    return {
      cell_id: result.cell_id,
      cell_type: result.cell_type,
      edit_mode: input.edit_mode,
      notebook_path: input.notebook_path
    }
  }
})

Supported operations

Why this matters

• Data science / ML / research workflows are a primary OpenCode use case — Jupyter is the dominant notebook format
• Cell-level edits preserve notebook integrity (outputs, metadata) that full-file overwrites destroy
• Dramatically reduces context needed: agent reads only the target cell, not the entire notebook
• Produces clean, reviewable diffs at the cell level

Acceptance criteria

• NotebookEdit requires WorkspaceWrite permission
• All three edit modes (replace, insert, delete) are implemented
• replace preserves existing cell metadata and outputs (only source is updated)
• Invalid cell_id returns a clear error listing valid cell IDs
• The tool creates a snapshot-compatible backup before editing (consistent with OpenCode's existing snapshot behavior)
• Malformed .ipynb files return a parse error, not a silent failure

Related / cross-reference

• claw-code reference: https://github.com/instructkr/claw-code/tree/main/rust (NotebookEdit tool)
• Learnings from claude-code source: Lessons from claude-code-main? #20475
• Original RFC: [FEATURE]: Rust-backed async diff engine via claw-code (fixes write/edit freeze + unlocks claw-code Rust primitives) #20479