How to use Claude to port MacPaint to Swift
Claude Code used original MacPaint source and a Gemini feasibility plan to produce a port, recover legacy icons and get the application running on iPad.
news.ycombinator.com
Prompt to try
Editorial adaptation, not the source author’s exact prompt. Replace bracketed inputs and review tool permissions first.
Port [legacy application source] to [target platform and language] using [feasibility plan]. Inspect [original disk image] for required assets, implement a parser if needed and recover resource-fork icons. Run the application and address [reported bugs].
Reach people exploring AI agents
See placements →What happened
The author reports getting the original MacPaint screen running after one or two bug reports, and says the application now runs on iPad and is used daily by their children.
Reported by minorbug on Hacker NewsHow the agent did it
- Provided original MacPaint source and a Gemini feasibility plan.
- Let Claude Code write an MFS parser and extract resource-fork icons.
- Submitted one or two bug reports before getting the original screen running.
Where a person stepped in
The author supplied one or two bug reports and reports daily use by their children; they did not read the generated code.
A person set the goal and reviewed the result.
The author wanted to see how far an old Macintosh application could be brought onto a modern Mac. They used the original MacPaint source released by the Computer History Museum, written in Pascal and 68k assembly, and pointed Claude Code at it with a feasibility plan built in Gemini. The author explicitly says they neither wrote nor read the generated code.
One obstacle involved the original tool icons. Those assets lived in the resource fork of a binary stored on an MFS disk image, Apple's pre-HFS filesystem from 1984. According to the author, Claude Code wrote an MFS parser, decoded the resource fork and extracted the icons. This let the port reuse the original application's resources.
After one or two bug reports, the author says the original screen was running. The project subsequently ran on iPad, where the author's children used it daily and competed over printing. The post offers a personal account of the result rather than a code audit or a detailed compatibility assessment. Its concrete evidence is the recovered interface, extracted assets and reported family use.
Who it's for: Developers experimenting with historical application ports and unfamiliar legacy asset formats.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Hacker News · minorbug
Frequently asked questions
How were the original icons recovered?
Claude Code wrote an MFS parser, decoded the original binary resource fork and extracted the tool icons.
Did the author inspect the generated code?
The author says they did not write or read any generated code. They supplied one or two bug reports before getting the original screen running.
More details
About this account
Claude Code produced the port and legacy asset parser; the author says they did not write or read its generated code.
Platform: Hacker News. Attribution: https://news.ycombinator.com/item?id=47317521. Prompt: Suggested (written by Agents In Use, not the author's). Sourced by the Agents In Use pipeline.
Credit: minorbug on Hacker News
Source published 10 Mar 2026
Source checked 14 Oct 2026
Tools and topics
Claude Code · Gemini · MacPaint source · MFS disk image
Legacy software · Swift · Porting
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.