PEGO

R120: Transient Rule Memo Policy

Rules whose ordinary memo results cannot be reused need not create entries. Transient-rule analysis removes that bookkeeping before parsing.

Mechanism and Invariants

Rules that call no other rule or have one grammar reference are classified for ordinary transient execution. A repeated position through the unique caller chain is already covered by the caller's memo policy. Left-recursion requirements remain intact. Documents still memoize transient rules because later edits can reuse their results; the classification does not remove incremental state.

Scope and State

Default eligible ordinary rule policy across closure, both VMs, generated Go Node/typed Go and TypeScript. Document memoization remains eager.

Reference Control

No transient-classification-only same-source control exists. Public memo disabling affects a broader rule group.

Evidence and Implementation

Record 001 combines transient rules with body elision/twins. It does not isolate transient policy's timing or memory effect.

Evidence records: 001.

Source owners: transientRules, Rule.Transient, ordinary versus Document memo decision, transient rule metadata emission.

The comparison policy distinguishes same-source controls, historical changes and full checkpoints.

Related mechanisms: R020, M050.

Optimization Catalog