Sixteen Versions Later, Here’s What I Learned About AI Coding

🔍 Read the full analysis: Sixteen Versions Later, Here’s What I Learned About AI Coding on ThorstenMeyerAI.com

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Thorsten Meyer says he built and released Altersteilzeit, a free web app for counting down the working days in a German partial-retirement arrangement, over five days with Claude Opus 5.5 acting as a coding agent. In an account published October 13, Meyer describes 24 co-authored commits across 16 versions, with the agent handling coding and production tasks while he directed the work, made design decisions and approved releases.

The project began on September 28, 2026, with a request for a one-minute animated film about the block model of Altersteilzeit. In that arrangement, a person works as usual during an active phase and then stops working during a passive phase of equal length; a 4:4 model, for example, pairs four working years with four years off. Meyer says the initial idea expanded into a public app by October 2.

The published app combines a working-day countdown, milestones, a daily saying, a short narrated film and a collection of 3D games. Users enter a phase date and select a model from 1:1 to 5:5. According to Meyer, calculations account for weekdays, public holidays in the user’s German federal state and entered leave. Other features include calendar exports, a printable countdown calendar, a bridge-day finder, badges and a team countdown.

Meyer says the games turn calendar time into levels and play mechanics, and that the app has seven languages and five German dialects. His article describes 1,224 voice clips, 17 sound effects, about 18,000 lines of JavaScript and Python, and 15 test scripts. He says the agent wrote code, tested features, documented work and deployed releases; he supplied directions and signed off on them. The article also says the app has no accounts, cookies or tracking, and calculates dates in the browser.

Where the Agent’s Work Ended

Meyer’s account offers a specific case study of what an AI coding agent contributed to a small software project—and what it did not decide. The reported output goes beyond a code prototype: it includes a public-facing product, multilingual text and audio, games, privacy choices and legal pages. That makes the example relevant to readers evaluating AI coding tools as part of a production workflow rather than as code-completion aids alone.

At the same time, the account is a first-person project report, not an independent evaluation. Meyer’s description suggests the speed came from combining agent-produced implementation with human direction and review. The product’s tone, central metaphor, voice choices and release approvals remained his responsibility. The story therefore does not establish that an agent can independently plan, validate and operate a comparable service without human oversight.

The app’s focus is also unusually specific: people tracking a German partial-retirement schedule. Its date calculations depend on public holidays and leave, details that can affect whether a countdown is useful to an individual. Meyer says the tool calculates these in the browser, but the article does not report an external audit of the calculations or user testing.

From One-Minute Film to App

Altersteilzeit is a German partial-retirement arrangement. Meyer explains that its block model separates an active work period from an equally long passive period. His initial request was for a short film to make the wait through the active phase more engaging; the app grew from that idea over five days.

Meyer’s timeline says the first day brought the film, date and working-day calculations, and early 3D game prototypes. Later days added multilingual support, the daily countdown, more games, badges, sound and narration. He reports that an iPhone scrolling problem required a hotfix during development. On the fifth day, he approved the release, then added German dialects as full language options.

The article’s headline refers to 16 versions; its project account also reports 24 commits, each co-authored by Claude Opus 5.5. Meyer presents the work as a collaboration in which he gave short instructions, often in German, reviewed results and made decisions, while the agent handled implementation and repetitive production work.

“The interesting part is not how much an AI agent can build, but what was still left for me to do.”

— Thorsten Meyer, describing the project’s central lesson

What the Account Does Not Establish

The article is Meyer’s own account of the project. It does not include independent confirmation of the development timeline, the reported code and media counts, or the app’s calculation accuracy. It also does not provide user numbers, user feedback, accessibility testing or a security review. Those details are not established by the source.

Meyer says the app calculates dates locally and has no accounts, cookies or tracking. The account does not describe an independent privacy or technical audit, or explain how every feature behaves across devices and German state holiday calendars. It is also unclear whether the app will be maintained, how errors will be reported, or whether its legal pages have been reviewed by a lawyer.

The App’s Next Test

Meyer’s October 13 article describes the app as publicly available, but does not announce a further release date, roadmap or evaluation. The next developments to watch are whether he publishes updates, adds user-requested features or reports on how the date calculations and other functions perform in use.

For readers considering the app, the immediate practical step is to check that the selected work model, state holidays and entered leave match their circumstances. For readers following AI coding tools, a useful next measure would be independently verifiable information about maintenance, testing and user experience—not only the speed and feature count reported by the developer.

Key Questions

What is Altersteilzeit?

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, a person works during an active phase and then has a passive phase of equal length.

What did the app include?

Meyer says it included a working-day countdown, milestones, a narrated film, 3D games, calendar tools, badges and a team countdown, with support for seven languages and five German dialects.

What did Claude Opus 5.5 do?

According to Meyer, the coding agent implemented features, wrote and tested code, produced text and audio assets, documented work and deployed releases. Meyer says he set direction, made product decisions and approved releases.

Was the project independently evaluated?

The source is Meyer’s first-person account. It does not report an independent audit of the app, its date calculations, privacy claims, development figures or user experience.

Source: ThorstenMeyerAI.com