1. Value-Free Rule Bodies, Value-Free Twins, Transient Rules (0B2c903)

• Value-free bodies. The body of a terminal-type rule, or of a rule whose action does not use $n, is compiled without building values. Captures still build theirs.
• Twins. A CST rule (no action, no terminal type) called where its value is discarded (#atomic, -, !, value-free bodies) gets a value-free twin with its own memo entries. Rules in left-recursive cycles never get twins, because mixing a valued and a value-free version inside one cycle would change seed-growing semantics.
• Transient rules. Rules that call no other rule, or that are referenced only once in the grammar, are not memoized in normal parses: their entries can never be reused (a single-reference rule is re-invoked at a position only when its unique caller is, and the caller chain ends at a memoized rule or the start rule). Document still memoizes them so edits can reuse results.
• Shared empty frame for capture-free scopes.
• Effect: JSON 442 → 144 ms, 183 → 76 MB.