In a chat client (MCP)

@casoon/opengrid-mcp brings <opengrid-grid> into chat clients that support MCP Apps. It is an adapter over the public API, nothing in the grid knows about MCP. Installing it, its sources and its tools are in the package README.

In practice

The source is orders: 240 rows, whose CSV also holds margin and note — fields the operator left out of fields.

1. Open a source: “Open the orders as a grid.” opengrid_open answers with the session, the six columns and total: 240 — no rows.
2. Filter and sort: “Only Germany, largest amounts first.” opengrid_set_view with a filter on country and a sort on amount answers Filter: country eq DE · Sort: amount desc · 88 matches; the grid applies it and says “Filtered by the assistant”.
3. The reader’s selection: the reader selects the four largest German orders in the grid and asks “What’s odd about the rows I selected?” opengrid_selection returns exactly those four rows: two identical orders, an amount with a quantity of 0, and a date after today.
4. Group and sum: “Revenue per country.” opengrid_set_view groups by country with amount summed; the model gets Grouped by: country · 240 matches, the grid shows six group sums and a total. The new view clears the selection.
5. A field it may not name: “Which orders have the lowest margin?” opengrid_set_view with a sort on margin is refused: sort: margin is not a column of this grid. opengrid_describe confirms the view is unchanged.

The view is the interface

Everything the reader chooses — sort, filters, columns, grouping, facets — is one value, the view. The model works on the same value: opengrid_set_view takes exactly what get_view returns, and opengrid_describe answers with it. The server counts a view the model sets without a browser, through the engine’s view_query — the same translation the grid uses for get_query.

Two directions

Reader → model	Each opengrid-view-change and opengrid-selection-change goes to the server, and one line goes into the model’s context: Filter: country eq DE · 52 matches · 3 selected.
Model → reader	The server keeps the session’s view. The grid asks for it when it becomes visible or focused and every few seconds while it is, and applies it with set_view(host, view, { notice }): one query, one announcement, the focus where it was.

Rows

The grid’s rows come through an app-only tool; the model never receives a source. It receives rows only when the reader selects them and asks for an analysis — as the grid’s query plus the selected positions, read on the server.

In the host’s sandbox

A view runs under the host’s Content Security Policy, which allows no WebAssembly. The package therefore ships the elements translated with wasm2js, built from the same Rust as @casoon/opengrid, inlined into one HTML file. tests/e2e/mcp-view.spec.js runs that file in a sandboxed iframe under the hosts’ default policy, against the real server.