Someone who had never opened a terminal put Estonian inside macOS

Before this project I had never opened a terminal. Total hands-on time was under half a day, spread across six calendar days — most of the elapsed time was an unattended download. What came out is a 1.5 GB offline toolkit that puts Estonian inside macOS: select any Estonian word anywhere in the OS, press Ctrl+Cmd+D, and read a real dictionary entry. ACHIEVEMENTS - Four dictionaries, 406,725 entries, running inside Apple's own Dictionary app — not a separate application, but the OS feature itself. - 5,168,360 inflected forms map back to their headwords. Estonian has 14 cases, so without this a dictionary is unusable: you almost never meet a word in its dictionary form. - Estonian spellcheck, which macOS does not offer: 5,328,332 word forms taught to the system spelling service. - Also ported to iPhone, and packaged as a one-click installer so a non-technical Estonian can install it without a terminal. - Coverage measured against a real frequency list, not claimed: 92% translation and 98% inflection coverage on the 1,000 most common words. TOOLS Claude Code (Opus) as the entire development environment, working in Estonian. Python, SQLite, Swift, Bash — ~2,744 lines. Ekilex API (Institute of the Estonian Language), Apple Dictionary Development Kit, pyglossary, Cocoa NSSpellChecker. METHODOLOGY - I could not review the code, so I reviewed the results: entry counts, coverage percentages, and entries for words I picked myself. - Validate before assembling. 178 MB of generated XML is checked against Apple's schema before the build tool sees it — which is how broken tags in national open data got caught. - Test with deliberate typos, not with hope. LEARNINGS - The hard part is not writing code. It is knowing what to verify. - AI is confidently wrong about operating system internals. My commits read "macOS 26 DOES support Hunspell" and, two commits later, "the Hunspell path is a dead end." A configuration entry proves configuration, not function. - Silent success is the dangerous failure mode. The spellchecker looked perfect — red underlines gone — while macOS was classifying Estonian as Finnish and checking nothing at all. - Negative results are deliverables. Three impossible approaches are now documented with evidence, so the next person loses hours instead of weeks. RELEVANT URLS - Ekilex, Institute of the Estonian Language: https://ekilex.ee - EKI open data archive: https://arhiiv.eki.ee/litsents/ - Estonian wordlist (160k words, 5.4M forms): https://github.com/KristjanPikhof/Estonian-Wordlist-Enriched-Ekilex Source data used under CC BY 4.0, CC BY-SA 4.0 and Public Domain, with attribution embedded in every dictionary bundle.