Ex-Google engineer says Claude Opus 5.5 wrote 30,000 lines of code in days

Wang Yonggang, a veteran engineer who previously worked at Google, published a long essay titled "Farewell, Programmer" on November 6, describing his experience developing software with AI. He mentioned that in September 2026, a computer science teacher in the United States contacted him hoping to improve the Altair 8800 computer simulator he had open-sourced six years earlier. Wang handed the request to Claude Opus 5.5 and asked the AI to provide suggestions from a system design perspective.

According to Wang, the AI not only fulfilled the original requirements but also proactively proposed adding an assembler, a debugger, and a teletype emulator interface. Over the following three to four days, the simulator grew from a few hundred lines of code into a project with over 30,000 lines of code, complete with unit tests and browser-based integration tests.

Wang said that during this period he mainly confirmed the approach, raised questions, and gave feedback, while the concrete technical decisions and coding were largely handled by the AI. He also noted that the AI could proactively research historical materials, seek out experts, help draft cross-language emails, and use external references to calibrate 3D models. In the project to recreate the Leibniz mechanical calculator, the AI helped him contact a museum in Germany, and he ultimately obtained 135 pages of historical drawings and manuscripts. Wang argued that AI is changing how software is traditionally developed: work that once took programmers a great deal of time can now be completed by AI within a few days, making him feel like "someone outside of AI."