PEGO
G200: Typed Local Capture Layouts
Complete capture-name metadata lets direct Go-local rules omit unreachable matching code without losing known nil captures.
Mechanism and Invariants
Ordinary rule layouts come from Node-rule metadata; owned/projected repetition layouts use the general collector, including dead syntax and predicate/projection rules. Locals are declared only when reads, marks or values require them. A known dead capture still reads nil, without introducing a runtime frame.
Scope and State
Applied by default only to eligible generated typed Go bodies. Node parsing/recognition, closure, VMs and TypeScript retain their separate routes.
Reference Control
No generation option selects an alternative for this mechanism. Typed Go
output comes from the Flow IR printer, and its generated parsers are compared
with the engine oracle in the internal/engine tests.
Evidence and Implementation
Record 084 measures same-generator 128-repetition ordinary, element-predicate and cut fixtures. All twelve accepted/rejected medians are below parity, about 0.711–0.829, with unchanged allocations. Generation fixtures shrink source and cost less in those samples; published parser outputs remain unchanged. These synthetic local-layout results do not establish a general generation or parsing benefit.
Evidence records: 084.
Source owners: typed structural emitter, framed body emission.
The comparison policy distinguishes same-source controls, historical changes and full checkpoints.