Draw a sketch and watch it back again with persistent WebStreams

Name: Draw a sketch and watch it back again with persistent WebStreams
Availability: InStock
Author: dwwoelfel

by dwwoelfel·Mar 17, 2026·1 point·0 comments

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AI Analysis

●●SolidWizardryZero to One

Persistent WebStreams replay drawings from JSON lines—novel infra for streaming apps.

Strengths

•Persistent WebStreams are genuinely novel—single-writer, multiple-reader data structure.
•Pointer events as JSON lines enables clean replay reconstruction from stream.
•Built by InstantDB team—backed by real database infrastructure, not a toy.

Weaknesses

•Demo product, not standalone tool—really marketing for InstantDB's new feature.
•Unclear what apps beyond drawing demos benefit from this streaming approach.

Post Description

Made this game as a testing ground for persistent WebStreams that we recently released at InstantDB.

We created the streams to make it easier to build apps that stream data from an llm to the client, but they’re fundamentally a single-writer, multiple-reader data structure.

The pointer events are stored as json lines in the stream, and then the replay reconstructs shapes from the events as they get played back.

The code lives at https://github.com/instantdb/inkdot