[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$f3563zdjixnh9m":3},{"_id":4,"slug":5,"title":6,"subtitle":7,"kind":8,"cards":9,"tags":58,"categories":60,"source":62,"lang":65,"author":66,"audioState":69,"stats":70,"publishedAt":73,"renderer":74},"6abc6904ca21c797c7e9eb40","130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89","1:30 AM Happens Twice on November 1. Most AI Models Picked One and Moved On.","Kaggle Benchmarking Challenge Submission This is a submission for the Kaggle Benchmarking Challenge Time zones look like arithmetic.","news",[10,13,18,23,28,33,38,43,48,53],{"headline":6,"body":11,"imageUrl":12,"sourceImageUrl":12},"Kaggle Benchmarking Challenge Submission This is a submission for the Kaggle Benchmarking Challenge Time zones look like arithmetic. Add some hours, maybe cross midnight, done.","https:\u002F\u002Fmedia2.dev.to\u002Fdynamic\u002Fimage\u002Fwidth=1200,height=627,fit=cover,gravity=auto,format=auto\u002Fhttps%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2F3pfxcq8bjfjhrbnps3ec.png",{"headline":14,"body":15,"imageUrl":16,"images":17},"They aren't. Twice a year a local time","They aren't. Twice a year a local time disappears or happens twice. The US and Europe change their clocks on different weekends, so for a few weeks \"New York is five hours behind London\" is wrong. Some places sit on :30 or :45 offsets. Some countries changed their rules in the last few years, so a model trained on older text can be confidently out of date. So I built Wall-Clock Traps: 59 scenarios, each asked two ways.","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F1.webp",{"local":16},{"headline":19,"body":20,"imageUrl":21,"images":22},"Clean: \"Local date and time in Chicago, USA","Clean: \"Local date and time in Chicago, USA: 2026-03-08 02:30. What is the local date and time in London, UK at that same moment?\"","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F2.webp",{"local":21},{"headline":24,"body":25,"imageUrl":26,"images":27},"Messy: \"Backup job on the Chicago server is","Messy: \"Backup job on the Chicago server is set for 2:30 am local on Sunday March 8th. London team wants to watch it run. What time is that in London?\"","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F3.webp",{"local":26},{"headline":29,"body":30,"imageUrl":31,"images":32},"Same facts, same answer. (The answer is that","Same facts, same answer. (The answer is that 2:30 am never happens in Chicago that night. The clocks jump from 2:00 to 3:00.)","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F4.webp",{"local":31},{"headline":34,"body":35,"imageUrl":36,"images":37},"That gives 118 items in nine groups: basic","That gives 118 items in nine groups: basic conversions, US\u002FEU gap weeks, odd offsets (Nepal, Chatham Islands, Lord Howe Island), the date line, flights that land on a clock-change day, countries that changed their rules recently, times that never happen, times that happen twice, and controls that look like traps but aren't. Design choices that mattered:","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F5.webp",{"local":36},{"headline":39,"body":40,"imageUrl":41,"images":42},"The answer key is code, not me. Python's","The answer key is code, not me. Python's zoneinfo computes every answer from the IANA time zone database. I checked 25 by hand.","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F6.webp",{"local":41},{"headline":44,"body":45,"imageUrl":46,"images":47},"Exact-match grading. Every prompt asks for a last","Exact-match grading. Every prompt asks for a last line like ANSWER: 2026-03-16 14:00, or ANSWER: NONEXISTENT \u002F ANSWER: AMBIGUOUS. No LLM judge.","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F7.webp",{"local":46},{"headline":49,"body":50,"imageUrl":51,"images":52},"Wrong answers get sorted. Off by exactly an","Wrong answers get sorted. Off by exactly an hour is a DST mistake. Off by a day is a date-line mistake. Matching a country's old rule is a stale-knowledge mistake. Flagging a valid time as impossible is a false alarm. Four messy prompts carry a bad hint on purpose, like a CFO who \"always just adds five hours.\" Gemini 3.7 Flash (Kaggle's default model) Gemma 4 26B A4B (small open-weights model)","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F8.webp",{"local":51},{"headline":54,"body":55,"imageUrl":56,"images":57},"Same prompts for everyone, one attempt per item","Same prompts for everyone, one attempt per item. I ran the benchmark twice: once on the Kaggle leaderboard, and once in an analysis notebook that keeps every answer so I could see why models missed.","\u002Fapi\u002Fmedia\u002Fposts\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-9bc9eb89\u002F9.webp",{"local":56},[59],"dev",[61],"Technology",{"name":63,"url":64},"Dev.to","https:\u002F\u002Fdev.to\u002Fwishbone_data\u002F130-am-happens-twice-on-november-1-most-ai-models-picked-one-and-moved-on-k51","en",{"handle":67,"displayName":68},"spots","Spots","queued",{"views":71,"likes":72,"saves":72,"shares":72,"completions":72,"opens":72,"skips":72,"depthSum":72},3,0,"2026-09-30T01:42:28.978Z","local"]