Notebook limitations

Lapis notebooks are markdown-native and intentionally narrower than full Observable notebooks or general-purpose Jupyter environments.

Supported today

JavaScript, TypeScript, SQL, and dynamic markdown cells
Explicit execution with stale-cell tracking
DuckDB over vault files and app metadata tables
Reactive view(Inputs.*) inputs with downstream reruns
Tables, charts, markdown, text, images, errors, and trusted html/svg
Static ESM imports for configured or installed packages
Generated output persistence across reloads

Not supported today

Area	Status
Python (`py` / `python`)	Not available
Full Observable JS	Mutable variables, generators, implicit invalidation, and `@observablehq/runtime` imports are out of scope
Observable imports	Use Lapis `lapis.*` helpers instead of Observable notebook imports
Relative cell imports	Rejected until notebook-local module resolution exists
Some input types	`button`, `checkbox`, `radio`, `select`, `file`, `search`, `table`, `form` throw if used
Public `nb` namespace	Removed; use `lapis.*` or documented bare globals

Observable-inspired subset

The System Guide notebook in a fresh vault exercises the current parity slice: async cells, display(), plain inputs, markdown interpolation, trusted html, and lapis.FileAttachment(). It documents what the runtime targets, not every Observable feature.

Browser vs desktop

Browser / PWA uses DuckDB-Wasm and vault adapter reads for file registration.
Desktop (Electron) can use a native DuckDB sidecar for filesystem vaults, which avoids moving large file buffers through the renderer.

Both hosts share the same cell syntax and lapis.* surface.

Safe Mode

Safe Mode can disable notebook execution while you review untrusted vault content. When execution is blocked, run commands surface a recovery notice instead of starting cells.

See Safe mode.