mitsuhiko: djs' JS "heap dumps" may beat real dumps for durable coding agents

mitsuhiko · x · 2026-11-08

Developer mitsuhiko highlights djs, which effectively implements "heap dumps" for JavaScript: a running program serializes its entire execution state at any debugger breakpoint into a tiny dump (473 B, 268 B gzipped in the demo) and can resume from that exact point later inside a fresh sandbox.
The demo runs interactively in the browser via WASM, showing a loop paused and resumed across three successive dumps.
His take: this mechanism could work even better than a real heap dump for durable coding agents, since agent execution state can be cheaply persisted and resumed across sandboxes for long-running, interruptible tasks.

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