Hallucination

Confidently-wrong model output. Two flavors with different causes and fixes:

• Factuality hallucination — invented or wrong facts about the world (a function that doesn't exist, a wrong API signature, a fake citation). Caused by parametric knowledge gaps, often past the knowledge cutoff. Fix: load the right contextual knowledge.
• Faithfulness hallucination — output drifts from the contextual knowledge that's loaded, the user's instructions, or the model's own prior reasoning. Symptom of attention degradation; worsens in the dumb zone. Fix: clear or compact.

Avoid: "hallucination" as a bare synonym for "wrong" — without naming the flavor, the term has no diagnostic value.

Usage:

"It hallucinated a parseAsync method on the schema."

"Factuality or faithfulness?"

"The method exists in the docs I pasted — it just stopped reading them after turn forty."

"Faithfulness then. Compact and reload, don't bother adding more docs."