A moment with a colour‑blind stakeholder changed the way I think about dashboards forever, and it eventually led me to build PBIX A11y, a free browser‑based accessibility checker for Power BI. What started as a painful realisation about how easily we can exclude people without knowing has grown into a practical tool powered by WCAG principles and Lovable, designed to help us catch accessibility issues earlier and build more inclusive reports. In this post, I share the story behind it, what the tool checks, and how the new Colour Blindness Simulator and Alt Text Generator fit into the journey.

We are going to design a Power BI semantic model that serves multiple reports built on top of a Snowflake / SQL warehouse using a typical Gold layer (fact and dimension tables) for a hybrid DeFi & TradFi analytics platform. The original question came from a real analytical query that joins two fact tables (FACT_TRADE_EXECUTION and FACT_WALLET_ACCOUNT) with several conformed dimensions (DIM_PROTOCOL, DIM_INVESTOR_TIER, DIM_ASSET_CLASS, DIM_INSTRUMENT_TYPE) and later mixes ledger-statement logic with window functions (ROW_NUMBER, SUM() OVER (...)).

The design decision was: one semantic model per fact table, one model per business subject area, or a single wide custom query that pre-computes everything?

This article summarizes the conclusions and aligns them with current Microsoft and community guidance.