Harden discriminated union reducer
Hard TypeScript arena: tagged unions, exhaustive checks, and reducer safety
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Missing prerequisites: typescript-easy-discriminated-union
A billing reducer accepts several action shapes and silently ignores new actions. You are working inside a TypeScript monorepo, and the arena only clears when the result is safe, deterministic, and explainable.
Learn to apply tagged unions, exhaustive checks, and reducer safety in a TypeScript monorepo while explaining the invariant, safety constraints, and hidden edge cases.
- Demonstrates tagged unions, exhaustive checks, and reducer safety
- Handles the visible sample and hidden edge cases
- Keeps output deterministic and explainable
- Avoids unsafe dynamic execution
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