When your live P&L drifts from the backtest you validated, the culprit is almost never psychology. It is code: the same metric computed two subtly different ways in research and in the live sizing path. Here is the parity oracle I now gate on, and the deeper rule behind it: live and research must call the same code, not two copies of it.
A data-quality gate that crash-loops on corrupt, stale or all-NaN data is not broken, it is working: the alternative is fail open, trading on garbage with silent defaults. Here is the war-story from both sides, the honest flip where an over-eager gate locked me out of a market, and the one portable rule: on bad data, refuse to trade and alert loudly, never proceed with a default that looks like data.
The most dangerous code in a trading repo is the throwaway research notebook. One structural rule, dependencies that flow in a single direction, keeps it out of production and turns invisible coupling into a number you can grep.
Choosing a quant trading framework is not a feature comparison between NautilusTrader, backtrader and a DIY loop. It comes down to one property, and a rubric you can apply to any engine: does your backtest run the same code as live?
Using a floating-point number for money is a classic bug, but in a trading system it does not just round a penny wrong: it silently mis-sizes a live position. Here is why, and why a Money type is not the fix you think it is.
A practical, end-to-end guide to moving a content site from WordPress to Next.js without losing your search rankings: the URL-preservation rule that governs everything, a content pipeline that survives the move, bilingual and RTL handling, the SEO and security work, and a cutover you can roll back.
Managed WordPress hosting is a tax you pay in money, in performance, and in security anxiety. Here is how I kept the WordPress editor I love, ran it locally for free, and served the public site as static HTML on the edge: a zero-dependency Node crawler I have open-sourced.
The 2026 business rates revaluation, valued at 1 April 2024, and the new duty to notify: what three-yearly lists demand of UK property data.