Formula-backed asset proof with Dagster Pipes and Node

[gregkonush]

I built a small example for a pattern I keep running into: Dagster should own the asset graph and materialization metadata, while a Node step owns spreadsheet-style formulas and returns a proof artifact.

The example uses PipesSubprocessClient to run a TypeScript process with @bilig/workpaper. The TypeScript side edits one workbook input, recalculates dependent formulas, serializes the WorkPaper JSON, restores it, and emits compact Dagster Pipes metadata plus a full proof file.

Runnable example:

https://github.com/proompteng/bilig/tree/main/examples/dagster-workpaper-asset

Writeup:

https://proompteng.github.io/bilig/dagster-workpaper-asset.html

Local validation I ran:

pnpm --dir examples/dagster-workpaper-asset run check
pnpm --dir examples/dagster-workpaper-asset run smoke

The smoke path verifies:

• edited cell: Inputs!B2
• total changes from 1458 to 2187
• WorkPaper JSON is persisted
• restored readback stays 2187
• verified: true

This is not meant to replace Excel for macros, pivots, external links, or exact desktop behavior. The point is narrower: when a Dagster asset needs reviewable business formulas, the formula step can produce calculated values and readback proof without driving Excel or trusting stale cached XLSX formula values.

Curious if this asset/Pipes boundary is useful to other Dagster users, or if there is a better Dagster-native shape for this kind of formula-backed materialization proof.