Where this conversation describes AI being used to build or deliver a product. Part of the AI in practice tracker.
Engineering & simulationSonnet 4.1less than a day (vs weeks of work)
Rain Paharia used Sonnet 4.1 to replicate map APIs and generate doc tests for her 'iddqd' library, reducing work that would have taken weeks into less than a day.
“I just told it to kind of replicate, you know, the same APIs across all of the other maps. … I just told the LLM to do that. … it took me, like, I want to say, like, less than a day to get, like, the whole thing ready.”
Engineering & simulationOpus 4.5found 3 real bugs
David Crespo used Opus 4.5 to analyze crash dumps and source code in the Ghostty terminal project, identifying three real bugs and writing bug reports without prior Zig expertise.
“I just have Opus essentially figure out. … it basically was able to, like, look at the code, statically analyze it, and find the source of these of I found three different bugs this way.”
Engineering & simulationOpus 4.52-3 hours (vs likely dropping the bug)
Rain Paharia used Opus 4.5 to investigate a SIGTTOU bug in nextest by analyzing source code from other projects, leading to a complete fix in about three hours.
“I I kind of gave this to OPUS four dot five. … it spent like ten minutes or so, and it actually wrote up a nice summary … it took me like maybe two or three hours to do.”
Engineering & simulationOpenAI models (VS Code)
Adam Leventhal used OpenAI models in VS Code to autocomplete an OpenAPI diff library and a CI tool, allowing him to build and demo the software in a short time.
“I started using some of the open API open API excuse me, OpenAI models in Versus Code … literally the rest of the program, I just had tab completed.”
Engineering & simulationClaude Opus 4.5
Rain Paharia used Claude Opus 4.5 to identify verification properties for the Kani model checker in a Rust project, accelerating her learning and application of formal verification.
“I just asked CloudOpus four dot five to, hey. Like, you know, come up with a few properties that we can can verify that way. And it just did that.”