Opening: The AI That Hallucinates Because You Taught It ToCopilot isn’t confused. It’s obedient. That cheerful paragraph it just wrote about your company’s nonexistent “stellar Q4 surge”? That wasn’t a glitch—it’s gospel according to your own badly wired data.This is the “garbage in, confident out” effect—Microsoft Fabric’s polite way of saying, you trained your liar yourself. Copilot will happily hallucinate patterns because your tables whispered sweet inconsistencies into its prompt context.Here’s what’s happening: you’ve got duplicate joins, missing semantics, and half-baked Medallion layers masquerading as truth. Then you call Copilot and ask for insights. It doesn’t reason; it rearranges. Fabric feeds it malformed metadata, and Copilot returns a lucid dream dressed as analysis.Today I’ll show you why that happens, where your data model betrayed you, and how to rebuild it so Copilot stops inventing stories. By the end, you’ll have AI that’s accurate, explainable, and, at long last, trustworthy.Section 1: The Illusion of Intelligence — Why Copilot LiesPeople expect Copilot to know things. It doesn’t. It pattern‑matches from your metadata, context, and the brittle sense of “relationships” you’ve defined inside Fabric. You think you’re talking to intelligence; you’re actually talking to reflection. Give it ambiguity, and it mirrors that ambiguity straight back, only shinier.Here’s the real problem. Most Fabric implementations treat schema design as an afterthought—fact tables joined on the wrong key, measures written inconsistently, descriptions missing entirely. Copilot reads this chaos like a child reading an unpunctuated sentence: it just guesses where the meaning should go. The result sounds coherent but may be critically wrong.Say your Gold layer contains “Revenue” from one source and “Total Sales” from another, both unstandardized. Copilot sees similar column names and, in its infinite politeness, fuses them. You ask, “What was revenue last quarter?” It merges measures with mismatched granularity, produces an average across incompatible scales, and presents it to you with full confidence. The chart looks professional; the math is fiction.The illusion comes from tone. Natural language feels like understanding, but Copilot’s natural responses only mask statistical mimicry. When you ask a question, the model doesn’t validate facts; it retrieves patterns—probable joins, plausible columns, digestible text. Without strict data lineage or semantic governance, it invents what it can’t infer. It is, in effect, your schema with stage presence.Fabric compounds this illusion. Because data agents in Fabric pass context through metadata, any gaps in relationships—missing foreign keys, untagged dimensions, or ambiguous measure names—are treated as optional hints rather than mandates. The model fills those voids through pattern completion, not logic. You meant “join sales by region and date”? It might read “join sales to anything that smells geographic.” And the SQL it generates obligingly cooperates with that nonsense.Users fall for it because the interface democratizes request syntax. You type a sentence. It returns a visual. You assume comprehension, but the model operates in statistical fog. The fewer constraints you define, the friendlier its lies become.The key mental shift is this: Copilot is not an oracle. It has no epistemology, no concept of truth, only mirrors built from your metadata. It converts your data model into a linguistic probability space. Every structural flaw becomes a semantic hallucination. Where your schema is inconsistent, the AI hallucinates consistency that does not exist.And the tragedy is predictable: executives make decisions based on fiction that feels validated because it came from Microsoft Fabric. If your Gold layer wobbles under inconsistent transformations, Copilot amplifies that wobble into confident storytelling. The model’s eloquence disguises your pipeline’s rot.Think of Copilot as a...