Building A Retirement Countdown: My AI Coding Agent, Version By Version

🔍 Read the full analysis: Building A Retirement Countdown: My AI Coding Agent, Version By Version on ThorstenMeyerAI.com

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Thorsten Meyer says he used the Claude Opus 5.5 coding agent to develop and release Altersteilzeit, a free web app for counting down working days to partial retirement, in 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 product direction, made design decisions and approved releases.

The app is designed around Germany’s Altersteilzeit partial-retirement arrangement, specifically the block model, in which a person works an active phase and then takes an equally long passive phase away from work. Users enter a start date and choose a schedule from 1:1 to 5:5. The app then calculates the other date and estimates remaining working days, accounting for weekdays, state public holidays and entered leave, according to Meyer.

Meyer says the finished site includes a daily countdown with milestones, a short narrated film, and a collection of 3D games that use years of the active phase as levels. Other features include calendar exports, a bridge-day finder, badges, a team countdown and a printable calendar. His account describes the release as supporting seven languages and five German dialects, with narration and other voice recordings.

The project was tracked across 24 commits, each co-authored by the coding agent, Meyer writes. He says the agent produced browser-based code, test scripts, translations, voice clips and sound effects, and helped with deployment. Those figures and the development timeline come from Meyer’s published account; the source material does not include an independent technical review or usage data.

A Countdown Built Around Daily Use

The project offers a concrete example of how a coding agent can be used across more than a single programming task. Meyer’s description covers implementation, testing, translation, audio production and deployment, while also documenting work that remained with him: deciding what the app should feel like, selecting voices and dialects, and approving what went live.

That division of work matters to readers evaluating AI-assisted software development. A fast build, as described by its creator, does not by itself establish the app’s reliability, accessibility or usefulness to other people. The project’s distinctive choices—turning calendar time into game levels and using the sea as an image for life after work—also show how product judgment shaped the result beyond code generation.

For people approaching partial retirement, a tool that converts a long schedule into daily progress and milestones may make the wait easier to track. The app’s stated browser-based calculations and lack of accounts or tracking may also appeal to users concerned about sharing personal dates. No independent assessment of those privacy claims is included in the source material.

From Film Request to Public App

Meyer says the project began on Monday, September 28, with a request for a one-minute animated film about the working days in an Altersteilzeit schedule. The initial scope grew during the following five days. The account describes adding date calculations and game prototypes on the first day, followed by language support, a daily view and more games on day two.

On the third day, Meyer says, the work expanded to include badges, a bridge-day finder and other features, alongside a fix for a mobile scrolling problem. Narration and sound effects followed on day four. Meyer says he reviewed and approved the release on day five, before adding five German dialects as full language options. The source describes nineteen 3D games in one passage, but later says the game was playable in fifteen modes; it does not explain how those counts relate.

Meyer says the site has no accounts, cookies or tracking and calculates dates in the browser. Shared dates, he writes, are stored after the “#” in a web address, a fragment not sent to the server in a standard web request. These are descriptions from the developer’s account, not findings from an external privacy audit.

“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

Usage and Technical Checks Unreported

The published account does not provide user numbers, independent testing results or an external security review. It is not clear whether the app has been checked for accessibility, how its holiday calculations are maintained as rules change, or whether the voice and translation output received review by native speakers beyond the process Meyer describes.

There is also a difference in the source’s descriptions of the game content: it refers to nineteen games and, elsewhere, to fifteen playable modes. The account does not clarify whether some games contain multiple modes or whether the figures refer to different versions. These details do not change the reported development timeline, but they limit what can be concluded about the final feature set.

Further Validation and Updates

Meyer’s account identifies the October 2 release and describes the app’s features, but it does not set out a schedule for future updates or provide a next development milestone. The next practical questions are whether the project will receive ongoing maintenance, how the developer will handle corrections to holiday and workday calculations, and whether independent checks will be published.

For now, readers can distinguish the documented development account from independently verified product performance: Meyer reports that the site is live and describes how it was built, while broader adoption, reliability and long-term support remain unreported.

Key Questions

What is Altersteilzeit?

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, a person works an active phase and then has a passive phase away from work.

What does the countdown app calculate?

Meyer says users enter a start date and choose a schedule from 1:1 to 5:5. The app calculates the corresponding phase date and remaining working days, taking weekdays, state public holidays and entered leave into account.

How long did development take?

Meyer says work ran from September 28 to October 2, 2026, with the public release approved on the fifth day. The timeline is based on his account.

What did the AI coding agent do?

According to Meyer, the agent helped write and test code, produce translations and audio assets, and prepare deployment. Meyer says he set the direction, made design choices and approved releases.

Has the app been independently verified?

The source material does not report an independent review of the app’s calculations, privacy claims, accessibility or security. Those aspects remain unverified in the account provided.

Source: ThorstenMeyerAI.com