feat(vscode): create empty notebooks via notebook_edit

[markijbema]

What changed

Adds a create action to the notebook_edit tool so an agent can create a new empty .ipynb on disk and then insert cells into it. This closes the "creating a fresh notebook doesn't work well" limitation noted in #11644.

• CLI (packages/opencode/src/kilocode/): new create action in the notebook protocol (EditRequest/EditResult), expected_revision made optional, already_exists error code. notebook_edit accepts action: "create" with no kind/source/index/expected_revision, validates before the permission prompt, and returns the new notebook's initial revision.
• VS Code extension (packages/kilo-vscode/src/services/notebook/): resolveNotebookCreatePath resolves the parent directory (must exist, inside the request root, pass access checks), rejects non-.ipynb and already-existing files. The adapter writes a minimal valid empty .ipynb, opens it, and returns the initial content revision.
• Regenerated @kilocode/sdk; added a changeset.

Why

The VS Code notebook API has no way to create a notebook file at a path — openNotebookDocument(type, data) only creates an unsaved untitled notebook with no on-disk path, which is why the original fresh-notebook flow failed. The bridge instead writes a minimal valid empty .ipynb to disk and opens it, so subsequent path-based notebook_edit/notebook_execute calls work.

Notes

• Reuses the existing notebook_edit permission and the experimental.native_notebook_tools experiment — no new permission, no cloud schema change.
• .ipynb only for this iteration; the parent directory must already exist (no mkdir -p); existing files are never overwritten.

Testing

• packages/opencode: typecheck + notebook tool/service tests (new create case).
• packages/kilo-vscode: typecheck + lint + 30 notebook unit tests (5 new create cases: success, already-exists, missing-parent, non-.ipynb, access-denied).
• SDK package typechecks; opencode-annotation and kilocode_change guards pass.

The full VS Code-host test suite was not run locally (.vscode-test IPC socket path is too long inside the worktree); CI will exercise it.

[kilo-code-bot]

Code Review Summary

Status: 3 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	3
SUGGESTION	0

Fix these issues in Kilo Cloud

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/src/kilocode/notebook/protocol.ts	147	already_exists is added to the protocol, but the VS Code bridge still downgrades it to execution_failed.
packages/kilo-vscode/src/services/notebook/adapter.ts	256	Notebook creation writes unconditionally after validation, so a concurrent creator can be overwritten instead of receiving already_exists.
packages/kilo-vscode/src/services/notebook/path.ts	125	Any realpath(target) failure is treated as "missing", which misclassifies provider/permission errors and feeds the overwrite path.

Files Reviewed (11 files)

• .changeset/notebook-create-action.md - 0 issues
• packages/kilo-vscode/src/services/notebook/adapter.ts - 1 issue
• packages/kilo-vscode/src/services/notebook/bridge.ts - 0 issues
• packages/kilo-vscode/src/services/notebook/path.ts - 1 issue
• packages/kilo-vscode/src/services/notebook/types.ts - 0 issues
• packages/kilo-vscode/tests/unit/notebook-core.test.ts - 0 issues
• packages/opencode/src/kilocode/notebook/protocol.ts - 1 issue
• packages/opencode/src/kilocode/tool/notebook-host.ts - 0 issues
• packages/opencode/test/kilocode/notebook-tools.test.ts - 0 issues
• packages/sdk/js/src/v2/gen/types.gen.ts - 0 issues
• packages/sdk/openapi.json - 0 issues

---

_{Reviewed by gpt-5.4-20260305 · Input: 147.2K · Output: 12.7K · Cached: 369.2K}

_{Review guidance: REVIEW.md from base branch main}