My AI Coding Agent Experiment: Five Days And A Retirement Countdown

🔍 Read the full analysis: My AI Coding Agent Experiment: Five Days And A Retirement Countdown on ThorstenMeyerAI.com

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Thorsten Meyer says he used Claude Opus 5.5 to help build and publish a free website for people counting down to partial retirement in Germany, expanding a one-minute film idea into a countdown app, games and multilingual audio over five days, from September 28 to October 2, 2026. Meyer describes the project as a collaboration: the agent wrote and tested code, while he set the direction, made product decisions and approved releases.

The site, called Altersteilzeit, is designed for Germany’s block model of partial retirement, in which a person works during an active phase and then spends an equal period away from work. Users enter a start date and choose a model from 1:1 to 5:5. The app calculates the corresponding phase date and remaining working days, subtracting public holidays in the selected German state and entered leave, Meyer wrote.

The finished site combines a daily countdown with a short film about the user’s two phases and a collection of calendar-based games. Meyer’s account lists 19 game modes, a team countdown, milestone badges, a bridge-day finder and calendar exports. It also describes seven languages and five German dialects, with narrated audio. The source article’s game description refers to both fifteen modes and nineteen games; the exact distinction between those counts is not explained.

Meyer says all 24 commits were co-authored by Claude Opus 5.5. He reports that the agent produced about 18,000 lines of JavaScript and Python, 15 test scripts and 1,224 voice clips, and helped deploy the site. These are figures from the project author, not an independently audited account. Meyer says he reviewed the results, including listening to audio and approving the release.

Human Decisions in an AI-Built App

The project offers a detailed account of how an individual developer used an AI coding agent across a small product build, from implementation and testing to translation and deployment. Its scale is more informative than a single generated prototype: Meyer describes a public-facing site with multiple features, languages and audio assets completed in five calendar days.

At the same time, the account does not establish that the agent worked autonomously or that the same pace would apply to other projects. Meyer identifies himself as the person who supplied the concept and tone, chose features and voices, checked the work and approved releases. For readers weighing AI coding tools, the account points to both the speed of delegated production and the continuing role of human review and product judgment.

From Film Idea to Countdown Site

Meyer says the project began on Monday, September 28, with a request for a short animated film about the working days in an Altersteilzeit arrangement. In the German block model described in the article, the active work phase is followed by an equally long passive phase; a 4:4 arrangement, for example, has four years in each phase. The app was intended to make the waiting period easier to track.

According to Meyer’s timeline, the first day added date calculations, two game prototypes and an online release. Subsequent days brought languages, the daily view, more games, badges, a bridge-day finder, narration and sound effects. On the fifth day, Meyer approved the result and added five German dialects. He also says the site was built to calculate dates in the browser, without accounts, cookies or tracking; shared dates are stored in the fragment after the “#” in a web address.

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

— Thorsten Meyer, project author

What the Account Does Not Verify

The source is Meyer’s own account, and it does not provide an independent technical review, usage figures or user feedback. It is unclear how much time he spent reviewing generated code, correcting defects or preparing the app outside the five-day timeline. The article also does not explain the difference between its references to fifteen game modes and nineteen games, or specify which languages are included in each feature. Claims about privacy and browser-side calculations are not accompanied by an external audit.

Use and Testing After Release

Meyer’s account describes the site as online after his approval on October 2, 2026, but gives no later release schedule or plans for additional features. The next useful indicators would be whether the app remains available, how users respond, and whether independent testing confirms its date calculations, privacy design and accessibility across supported languages and devices.

Key Questions

What did Meyer build with the AI coding agent?

He says the agent helped build Altersteilzeit, a free web app with a working-day countdown, a short film, calendar tools, games, translations and narrated audio.

How long did the project take?

Meyer says development ran from September 28 to October 2, 2026, a five-day period.

Did the AI agent make all the decisions?

No. Meyer says he provided the idea and direction, made choices about tone and features, reviewed outputs and approved releases. The agent handled coding and other production tasks he delegated.

What is Altersteilzeit?

In the block model described by Meyer, a person works through an active phase and then enters an equal-length passive phase. The app calculates working days remaining based on dates, regional public holidays and leave entered by the user.

Has the app’s privacy or performance been independently checked?

The source account says calculations happen in the browser and that the site has no accounts, cookies or tracking. It provides no independent audit, performance review or user data.

Source: ThorstenMeyerAI.com