A per-path visited set alone makes a chain of diamonds (node i reads node
i+1 on both inputs) exponential in depth. Each node's text is now
memoised so it is expanded once, every expansion is charged to the shared
MAX_VISITS budget, chains deeper than MAX_DEPTH (64) are unknowable so
recursion stays bounded, and text longer than MAX_TEXT_LENGTH (100k) is
unknowable so StringConcatenate doubling cannot exhaust memory.
Vito Sansevero
8e2578ceb6