CTO at @imprintpayments. Wrote some books.

Joined March 2007
237 Photos and videos
Pinned Tweet
19 Mar 2020
A lot of folks want a map to Staff Engineer, and just as many Staff Engineers want to better understand their role. Towards that end, I'm working on a small project to collect folks' stories of reaching and operating as staff-plus engineers staffeng.com/
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Will Larson retweeted
The traditional way to make AI legible to bank auditors: decision trees. The problem: decision trees make terrible experiences. @Lethain and @ImprintPayments built an agent that reasons — then made that legible to regulators. Behind the build: sierra.ai/customers/imprint
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My X search results are all from 2011 now, but it did reveal that someone shared one of my posts to @jeff_weinstein in 2011 which is very Small World
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Does X have a diff search index archive for really old stuff on eg s3 or smthg? So many question
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In the year 2081, everybody was finally equal—and not just before God and the law. They were equal in focus, equal in productivity, and above all, equal in their inability to finish anything. This equality was enforced by the relentless supervision of Claude.
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Will Larson retweeted
I get asked every now and then: "how do I become more influential, as a dev/eng leader, better known online?" Either for themselves, or to help put their company on the map. The single best thoughts on this come from @Lethain, from this article: lethain.com/tech-influencer/
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Is fascinating watching our 5yo learn math from an iPad app, just shockingly quickly. But then also not be able to reproduce any of the concepts on paper 😅 Will keep iterating to figure out how to get concepts to transfer or if somehow the ideas aren’t actually landing.
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The agentic passive voice: any sentence in the active voice, where the actor is a model, is actually in the passive voice. Example: Claude messed up my code. Example: Codex wrote some bad tests. The passive voice is unclear, please avoid it.
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Will Larson retweeted
Ok here we go!! StaffEng, AI edition, with @voidfiles and yours truly. Sign up for our listening tour and to nominate guests! (Link in thread)
Now that I’m a few years out from podcast.staffeng.com… I kinda miss doing a show. Maybe I’ll start something new. Probably about AI best practices for eng leaders in big tech—the future is more unevenly distributed than ever. @voidfiles wanna join? @lethain wdyt?
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Wrote up a series of nine short posts on interesting problems we encountered while building an internal agent framework (virtual files, compaction, LLM vs code-driven workflows, etc) lethain.com/agents-series/
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Will Larson retweeted
Year EIGHT as a founder CTO. 2025 felt like a decade. The year of vibe coding, Apple opening payments, almost getting acquired, saying no, scaling past 100 people, mistakes, cultural memes, and figuring out how to go long. miguelcarranza.es/cto-year-8
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Will Larson retweeted
13 Dec 2025
This from @obie captures how I'm feeling about coding agents
12 Dec 2025
Even if current LLM progress hits a brick wall at Opus 4.5 level (and I doubt that will happen) the next 12 months are still going to be a staggering time of change in this industry as decision makers start truly understanding the new reality we live in. obie.medium.com/what-happens…
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9 Dec 2025
In the spirit of working in the open (and not eg preaching from the pulpit), I wrote up my notes on driving internal AI adoption and would love to hear what other practitioners are trying! lethain.com/company-ai-adopt…
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Will Larson retweeted
27 Nov 2025
There are certain things in business you DON'T want to learn by doing. You want to learn them by reading instead. This week’s Commoncog essay is about exactly this odd phenomenon. It was sparked by a conversation that I had on Twitter:
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Will Larson retweeted
Just in time for 2026 planning! Looking forward to the read through @Lethain
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Will Larson retweeted
18 Nov 2025
Replying to @Lethain
@Lethain Congrats on shipping! This is a subject area that applies to my day to day more than ever, so can’t wait to dig through.
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18 Nov 2025
This is exactly the use case I released LLM optimized edition of my latest book for amazon.com/dp/B0FXN2J4PJ?ref…
I’m starting to get into a habit of reading everything (blogs, articles, book chapters,…) with LLMs. Usually pass 1 is manual, then pass 2 “explain/summarize”, pass 3 Q&A. I usually end up with a better/deeper understanding than if I moved on. Growing to among top use cases. On the flip side, if you’re a writer trying to explain/communicate something, we may increasingly see less of a mindset of “I’m writing this for another human” and more “I’m writing this for an LLM”. Because once an LLM “gets it”, it can then target, personalize and serve the idea to its user.
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18 Nov 2025
(The digital version has a link to markdown file of full book)
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