{"slug": "show-hn-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude", "title": "Show HN: A semantic fuzzer for Obsidian Sync... in spite of Claude", "summary": "A developer built a semantic fuzzer that runs Obsidian instances in containers, edits notes while cutting off their network, and documents failure rates to reproduce Obsidian Sync data-loss bugs reported on the Obsidian forum for over 2 years. The developer guided Claude Code to build the fuzzer without reading the code, a process that ballooned to 60 hours and prompted a separate experience report on the failure modes. The fuzzer finds short, reproducible sequences that cause data loss for Obsidian Sync subscribers, with repro steps in the README.", "body_md": "The Obsidian forum has threads reporting Sync data loss for over 2 years. To help reproduce bugs, I built a fuzzer that runs Obsidian instances in containers, makes them edit notes while cutting off their network, and documents the failure rates.\n\nThe fuzzer finds amusingly short sequences that cause data loss and that you can reproduce on your own in a minute (if you have an Obsidian Sync subscription). Steps in the repro README.\n\nI guided Claude Code to build the fuzzer, but I didn't read the code. This didn't go well. The project ballooned to a painful 60h, so I wrote a separate experience report on the many failure modes and what I'll do differently next time: [https://hmijail.substack.com/p/building-a-semantic-fuzzer-fo...](https://hmijail.substack.com/p/building-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude)\n\nComments URL: [https://news.ycombinator.com/item?id=49907352](https://news.ycombinator.com/item?id=49907352)\n\nPoints: 1\n\n# Comments: 0", "url": "https://wpnews.pro/news/show-hn-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude", "canonical_source": "https://github.com/hmijail/ObsSyncBugHunt", "published_at": "2026-09-30 11:26:09+00:00", "updated_at": "2026-09-30 11:48:57.427293+00:00", "lang": "en", "topics": ["ai-tools", "developer-tools"], "entities": ["Obsidian", "Obsidian Sync", "Claude Code", "Anthropic"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/show-hn-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude", "markdown": "https://wpnews.pro/news/show-hn-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude.md", "text": "https://wpnews.pro/news/show-hn-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude.txt", "jsonld": "https://wpnews.pro/news/show-hn-a-semantic-fuzzer-for-obsidian-sync-in-spite-of-claude.jsonld"}}