Agent Skills · Python · WebAssembly
Rental yield, parcel sheet, company accounts. The three Python scripts of the investor-skills repository run in your browser, with no account and no intermediate server. They compute and describe; they do not advise.
An Agent Skill is a folder an AI assistant can read: a SKILL.md that says when to use it and how, and scripts it runs. The model judges, the script computes. Here there is no assistant: you fill in the form, your browser runs the Python script exactly as published, and the output is shown as printed, in English.
On the first computation, the browser loads Python for the web (about 13 MB, cached for a week). The yield is computed without sending anything; the parcel sheet sends the address to the Foncier service; the accounts query two public State APIs. Details
1 · rental-yield-france · rendement.py
Gross, net, net after tax over the chosen horizon, monthly payment and yearly table. Four regimes: micro-foncier, réel foncier, LMNP micro-BIC, LMNP réel. The prefilled values are the script’s example, not a real property.
2 · land-due-diligence-france · due_diligence.py
The Foncier service gathers cadastre, sales, planning, energy certificates and risks for an address. The script reads that envelope, ranks the signals (red, orange, info), compares an asking price with nearby sales and cites every source. What is missing is declared, never filled in.
3 · french-company-accounts · comptes.py
Turnover, net result, ratios published by INPI, cross-checked with the company directory. The script reconciles the two sources, flags publication anomalies and gives the change between the first and the last closing date shown.
The skills compute and describe. They give no personalised advice: the reader decides and checks the originals. No property, loan or company of the author appears in the examples; the outputs are the scripts’ own, in English, untouched.
The three skills are published under the MIT licence, with their tests, evaluation sets and continuous integration. Each SKILL.md tells the assistant when to use the skill, what to ask first, and reminds it that it does not advise. The scripts served here are copied from the repository at commit 2e2d03b, on 2026-10-14.
Pyodide is CPython compiled to WebAssembly. It is served by this site, not by a CDN, and runs in a Web Worker so the page never freezes. The scripts run as published, exactly as on the command line: same arguments, same exit codes. A refusal by the script (ineligible data, invalid input) is shown raw, with its code.
The browser plays the network’s part. For the parcel sheet, it sends the address to the Foncier service and hands the JSON envelope to the script; for the accounts, it reads the two public APIs and hands their responses to the script in recorded mode. The script itself never opens a connection. The Markdown output is turned into text and tables, never interpreted as HTML.
The served scripts are checked byte by byte by the site test against the published manifest: manifest.json
Nothing is sent to this site: the forms are never submitted to a server, and there are no cookies or trackers. The yield is computed entirely in your browser.
The parcel sheet sends the address to the Foncier service, hosted by Scaleway in France, which queries the public sources and does not log the address. Quota: 10 sheets per hour per visitor, 300 per day in total. Sales are displayed only on request, never published as fixed pages.
The accounts query directly, from your browser, the company directory (recherche-entreprises.api.gouv.fr, DINUM) and the INPI financial ratios published on data.economie.gouv.fr: both services see your IP address and the SIREN or name entered. The figures are those filed and published; their accuracy rests with the filers.
The tax rules behind the yield are those read on 11 October 2026 in the official sources; the script cites every rule it applies in its output. A sheet replaces neither an official risk statement, a planning certificate nor a valuation; a yield replaces neither tax advice nor a bank simulation.