pattern_value_eval_failed

A (pure …) expression leaf failed to evaluate at the cycle-0 dry-run.

A form in (pure …) value position is an expression of time: (pure (* 0.5 (+ 1 (sin (* (tau) cycle))))), evaluated per hap with cycle / tick / seed bound. At compile time the engine dry-runs it once at cycle 0 / seed 0; static validity is seed-independent, so cycle 0 catches the whole document-defect class an unbound name, division by zero, an arity error, a resource budget. The leaf then degrades to silence and this code is collected. A failure that only appears at a later cycle (e.g. (/ 1 (- cycle 2)) at cycle 2) is NOT this code: it is a domain hole, so that one hap is silently dropped and the rest of the pattern queries normally.

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Run sjon explain pattern_value_eval_failed to read this at a terminal, browse every code, or work through diagnostics-driven repair if you want the habit rather than the answer.