Build an instant-opening markdown viewer for macOS just for yourself
He had Claude Code with Opus 5.5 build him a markdown viewer from his own JSON viewer codebase, asking for speed above all, as personal software.
Source
arjie on Hacker News · 2026-10-22
Written in our own words. Credit to the original author. Link checked 2026-10-23.
What they did
He had Claude Code with Opus 5.5 build him a markdown viewer from his own JSON viewer codebase, asking for speed above all, as personal software.
Result (as claimed)
He says it opens files faster than any other macOS app he uses.
Tools they used
Cost: Claude Code: from $17/mo; Claude Opus 5.5: from $4 in / $20 out per 1M tokens.
Set it up
Pick a contained repo or task
Start on a branch or side project where mistakes are cheap.
Install and configure
Set up Claude Code, Claude Opus 5.5, macOS. Read what it can run on your machine and limit permissions where possible.
Run it on a real task
Give it a well-scoped issue and let it work. Review the diff like any pull request.
Add guardrails
Keep tests and CI in the loop, and never let an agent push to main or touch production secrets unattended.
Copy the full setup prompt
Paste into your agent and it will walk you through the setup, asking before anything that sends, posts or spends.
You are helping me set up this AI use case end to end in Claude Code. Goal: Build an instant-opening markdown viewer for macOS just for yourself What the original author did: He had Claude Code with Opus 5.5 build him a markdown viewer from his own JSON viewer codebase, asking for speed above all, as personal software. Reported result (as claimed by the author): He says it opens files faster than any other macOS app he uses. Source: https://news.ycombinator.com/item?id=50192584 Tools they used: Claude Code, Claude Opus 5.5, macOS Category: Dev & ops Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
You are helping me set up this AI use case end to end in Codex. Goal: Build an instant-opening markdown viewer for macOS just for yourself What the original author did: He had Claude Code with Opus 5.5 build him a markdown viewer from his own JSON viewer codebase, asking for speed above all, as personal software. Reported result (as claimed by the author): He says it opens files faster than any other macOS app he uses. Source: https://news.ycombinator.com/item?id=50192584 Tools they used: Claude Code, Claude Opus 5.5, macOS Category: Dev & ops Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
You are helping me set up this AI use case end to end in Grok Bot. Goal: Build an instant-opening markdown viewer for macOS just for yourself What the original author did: He had Claude Code with Opus 5.5 build him a markdown viewer from his own JSON viewer codebase, asking for speed above all, as personal software. Reported result (as claimed by the author): He says it opens files faster than any other macOS app he uses. Source: https://news.ycombinator.com/item?id=50192584 Tools they used: Claude Code, Claude Opus 5.5, macOS Category: Dev & ops Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
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Guides for this use case
How to vibe code an app with Claude Code ยท How to build private apps just for yourself with AI
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