🔍 Read the full analysis: How Five Days Of AI-Assisted Work Produced 16 Versions on ThorstenMeyerAI.com
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TL;DR
Thorsten Meyer says he and the Claude Opus 5.5 coding agent he used built a free web app for tracking German partial retirement over five days, from Sept. 28 to Oct. 2, 2026. The account describes 16 versions and features including a countdown, film, multilingual narration and 3D games; Meyer says he set the direction, made key choices and approved releases.
Developer Thorsten Meyer says he used the Claude Opus 5.5 coding agent to build and release a free web app for tracking German partial retirement in five days, expanding an initial one-minute film into a countdown tool with games, multilingual audio and a public website. His account, published Oct. 13, describes 16 versions and 24 commits co-authored by the agent, while Meyer supplied direction, made product decisions and approved releases.
The project began on Monday, Sept. 28, with a request for a short animated film about the working days remaining in an Altersteilzeit arrangement. Altersteilzeit is a German partial-retirement arrangement; in the block model, a person works through an active phase and then spends an equal period in a passive phase. By Friday, Oct. 2, Meyer said the project had become a public web app.
Users enter a date for the start of either phase and choose a model from 1:1 to 5:5. The app calculates the other date and counts weekdays, subtracting public holidays for the selected German federal state and leave entered by the user. Its features include a daily countdown with milestones, calendar exports, a printable calendar and a bridge-day finder. Meyer also describes a short film based on a user’s dates and a game collection that maps time in the work and retirement phases to play.
The account lists seven languages and five German dialects, a team countdown, badges and legal pages. Meyer says the agent handled much of the coding, testing, translation and production work, including 1,224 voice clips and 17 sound effects. He describes his role as setting the idea and tone, choosing voices and dialects, reviewing outputs and approving deployment. These details come from the developer’s own report; no independent audit or project records are provided in the source material.
Infographic 01 · From a one-minute film to a small studio’s output
Five days, sixteen versions
One person giving directions, one AI coding agent building and testing. Every day ended with something live that anyone could open in a browser.
Mon 28 Sep
4 commits2 games1 lang.
- v1A 51-second film of both phases, with a generated soundtrack
- v2–v3Leave, real working days, humour; anyone can enter their own dates
- v4–v5Two 3D game prototypes become one game: every year is a level
- v6Online on Netlify with landing page and seven legal pages
Tue 29 Sep
4 commits7 games7 lang.
- v7Seven languages everywhere, plus the daily view
- v8Office-chair kart: the third way to play
- v9Four more games, including mini golf for the passive phase
Wed 30 Sep
5 commits19 games7 lang.
- v10Badges and six everyday features
- v11–v12Seven more games, from paper plane to sailing regatta
- v12.1Hotfix: pages scroll on iPhone again
- v13Bridge-day finder, wish list, year review, four difficulty levels, five new games
Thu 1 Oct
6 commits19 games7 lang.
- v13.1“Time for AI”: the countdown recommends an Inside AI building
- v14A narrator in seven languages: film, saying of the day, game announcer
- v14.1–14.2One voice per role and mood; iOS audio fix
- v15Sound effects for film and games
Fri 2 Oct
5 commits19 games12 lang.
- Approval“All OK, roll it all out.”
- v16Five German dialects as full languages, voices included
- v16.1Announcement in twelve languages
Source: project repository and development log, 28 Sep – 2 Oct 2026; live site altersteilzeit.netlify.app.
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What the Five-Day Build Shows
The account offers a concrete example of how an AI coding agent can contribute to a small software project when a human supplies product direction and review. Rather than describing a single code-generation task, Meyer reports a chain of work spanning feature development, testing, localization, audio production and deployment. That breadth is the central point of his account.
The project also illustrates the distinction between producing software quickly and deciding what the software should be. Meyer says the concept, humor and cinematic framing were his choices, as were decisions about voices, dialects and publication details. The report does not establish how much time the project would have taken without an agent, or how its output compares with a conventional team. Its figures should be read as the creator’s account of this project, not as a general measure of AI development speed or quality.
For people approaching retirement, the app’s practical value lies in turning a date-based calculation into a daily tool, with holidays and entered leave reflected in the total. Meyer says the app calculates in the browser and requires no account, cookies or tracking. Those privacy and feature descriptions are also claims in the project report, rather than independently verified findings.
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From Film to Retirement Tool
The app is built around the block model of Altersteilzeit, in which a working active phase is followed by a passive phase of equal length. Meyer says the tool supports arrangements ranging from 1:1 to 5:5 and calculates working days using the user’s German federal state, public holidays and entered leave. The source does not explain how it handles every possible employment contract or regional exception.
Meyer’s account describes an iterative five-day schedule. The first day brought the film, date calculations and early game prototypes; later days added the daily view, games, language support, a bridge-day finder, badges, narration and sound. On the fifth day, Meyer says he approved the release and added five German dialects as full language options. The article refers to 19 3D games in its opening, while a later passage says the game is playable in fifteen modes; it does not clarify whether those counts refer to different ways of grouping the games.
The source says the app runs as single-file HTML pages and that shared links put dates after the “#” in a URL, which browsers do not send to the server in ordinary requests. It also says the project included about 18,000 lines of JavaScript and Python and 15 test scripts. These are developer-reported specifications; the article provides no code repository or outside technical review.
“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 focus
What the Project Account Leaves Open
The source is a first-person account by the app’s creator, not an independent assessment of the development process. It does not provide a repository, version history, external testing results or a breakdown of how much time Meyer spent directing and reviewing the agent. The claim that 24 commits were co-authored by Claude Opus 5.5 is reported by Meyer, and the article does not describe how authorship was recorded.
Some product details are not fully reconciled: the article mentions 19 3D games but later describes fifteen game modes, without explaining the difference. It also does not identify the exact public release date, provide usage figures or report whether users have tested the holiday and working-day calculations across different employment situations. The source gives no evidence on accessibility, ongoing maintenance, or how the app’s legal pages were reviewed.
Release, Testing and Maintenance
The source describes the app as public and free by Oct. 2, but does not announce a future release schedule, planned features or a next milestone. It is not clear whether Meyer intends to keep adding languages or games, or how often the app will be updated.
For readers considering the tool, the next practical step is to check its calculations against their own employment arrangement and the relevant state’s holidays. Further reporting could establish how the app handles edge cases, whether its privacy claims have been reviewed, and whether users find the countdown useful. No independent evaluation or adoption data is included in the account published Oct. 13.
Key Questions
What is the Altersteilzeit app?
It is a free web app that Meyer says tracks working days remaining in a German partial-retirement arrangement. It includes a countdown, milestones, a film, games and calendar tools.
How long did development take?
Meyer says work ran from Sept. 28 to Oct. 2, 2026, a five-day period. His account says the project went through 16 versions and 24 commits co-authored by the coding agent.
What did the AI agent do, according to Meyer?
Meyer says the agent wrote and tested code, supported translation and produced audio and other release materials. He says he set the direction, made decisions about the product and reviewed and approved releases.
Does the app collect personal data?
Meyer says dates are calculated in the browser and that the app has no accounts, cookies or tracking. That description comes from the developer; the source does not include an independent privacy audit.
Is the app’s performance independently verified?
No independent technical review, user testing results or usage figures are included in the source material. The development timeline, feature list and project metrics are reported by Meyer.
Source: ThorstenMeyerAI.com
