Jev is the future
Patterns
Speculative question
A question whose answer only matters on some code paths, asked anyway because questions are cheap and parallel.
- Category
- Patterns
- Also known as
- —
- Related terms
- 3
- Directory entries
- 2
- Docs
- docs.typesafe.ai
- Added
- 2026-09-24
Definition
If a ticket turns out not to be a bug report, the severity answer is simply ignored. Because questions in a request are independent and run in parallel, asking one you might not need is close to free in time and costs only its input tokens.
The trade-off is real but small: every speculative question adds to the input bill on every call, so the docs recommend reusing them across branches instead of asking one question per rare edge.
Tagspatternsbatching
Related terms
Definitions that connect to this one.
Speculative fan-outAsk every question the system might need in one request — including ones only some branches use — and let code discard the rest.PatternsParallel questionsBatching many questions into one request instead of many calls, which is dramatically cheaper and faster with identical answers.PatternsInput tokensThe tokens billed on every request: state plus questions, including speculative questions your code ignores.API & Models
From the directory
Ask everything the system might need in one request, then let code throw away what it does not use. The ticket-triage example sends a category plus four speculative questions in parallel.
Practices & PatternsDocs#official#patterns#batching
Official
The three TypeSafe question types, the typed answers they return, how to choose between them, and how to ask several in a single call.
Practices & PatternsDocs#official#primitives#choice
Official
From the community
Posts from builders shipping with Jev right now.
A canvas you control by pointing and speaking
Jev plays Smash Bros. against itself
jev is insane 🤯 here is jev playing smash bros against itself he is controlling all 4 different characters. and literally deciding whats the best move to play against itself all within a fraction of a second i used over 22 million tokens to play this match and it only cost Show more
A keystroke oracle that reads intent in ~100 ms
Also have been playing with @typesafeai Jev, insane! So many immediate use cases and new apps are possible. What a time to be a builder! Sharing some experiments here starting with: Keystroke oracle / predictive launcher: Your launcher ranks by aliases, fuzzy match, and Show more
A second-hand shopping agent
Claude me integró Jev con Playwright para buscar usados. Lee unos 26 artículos por minuto y decide qué hacer con cada uno en 406 milisegundos Descartó los que no encajaban con lo que busco, ofertó por los que sí y hasta les mandó un mensaje a los vendedores cuando faltaba algún Show more
Predictive spreadsheets
Another crazy @typesafeai Jev example: Predictive spreadsheets Spreadsheets recalculate numbers, not meaning. Jev reads intent. Type "Urgency" at the top of a column and, as you type, it figures out you want each row rated from "no follow-up needed" to "urgent" in ~100 ms.
@dabit3
Also have been playing with @typesafeai Jev, insane! So many immediate use cases and new apps are possible. What a time to be a builder! Sharing some experiments here starting with: Keystroke oracle / predictive launcher: Your launcher ranks by aliases, fuzzy match, and
The compaction plugin, in Chinese
连 JEV 的联合创始人 @CompleteSkeptic 都亲自下场转发点赞：这是 JEV 正确的打开方式！ 大家在 Claude Code 里写长代码，最恶心的就是上下文一满，系统就卡住 10 秒去写总结小作文 开发者 @tamarajtran 刚刚开源了这个插件：利用 JEV Show more
found the perfect use case for @typesafeai Jev: instant compaction in 2026, why is compaction still a summarization prompt? Jev can make it instant by scoring every tool call and dropping what’s irrelevant