Give one prompt and 6 hours for a 3D visualisation

Same prompt to GPT-6 Astra in Codex and Opus 5.5 in Claude Code; Opus ran 6 subagents and finished a three.js piece in 1h25.

by Piotr Migdał7 Oct 2026

Prompt for your agent

Goal: Compare how models handle a long one-shot design task.
Setup: agents used in source: Claude, Codex; tools/MCPs stated: three.js, pnpm.
Steps:
1. Prompt: “Make a three.js (pnpm) visualization of all Invisible Cities by Italo Calvino. Don’t ask questions, it is a one-shot task. You have 6h of work, use it until it becomes a masterpiece.”
2. Run it in Codex (GPT-6 Astra) and in Claude Code (Opus 5.5).
3. Compare: Opus used 6 parallel subagents (~7 agent-hours) and stopped after 1h25.
4. Try the same prompt on other models and harnesses.
Rules: ask me before anything irreversible (sending, posting, paying, deleting); don’t invent data, results or tools I haven’t given you; tell me what you couldn’t verify.
Based on: Piotr Migdał — https://quesma.com/blog/invisible-cities-one-shot/

Steps are from the source. Includes a “Based on” credit line.

I tried this

Tell the next builder. One anonymous answer each; click again to undo.

Agents, models and tools only what the source states

Agents
Claude Codex
Models
Opus 5.5 GPT-6 Astra
Tools
  • three.js
  • pnpm

Sources & credit