PEGO
R110: Document Run Record Retention
An unchanged Document parse that hits the root memo should not discard long-repetition records needed by the next edit. Retaining the same-generation map avoids losing resumption work.
Mechanism and Invariants
Only an edit advances run generation. An unchanged parse keeps its map, and a rebuilt repetition can replace a record within it. A parse after an edit creates the next map; two unparsed edits, aborted execution and edit-log rollover retain their invalidation rules. No records or replacement map are copied on the unchanged path.
Scope and State
Default Document bookkeeping for closure and both VMs. Generated parsers and TypeScript have no Document API.
Reference Control
No maintained same-source clear-map comparator exists. The focused evidence compares the historical parent and candidate.
Evidence and Implementation
Record 070 uses a 100,000-line fixture with a redundant unchanged parse outside timing, then times Edit plus final Parse. Retention restores 99,999 resumed elements; closure CodePoints drops from 6.90 to 0.778 ms and 48.83 to 1.15 MB. Without that redundant parse, timing ranges overlap and allocations stay fixed. This historical result concerns the unchanged-parse-before-edit sequence, not unchanged-parse cost or batch speed.
Evidence records: 070.
Source owners: Document.runGen and run-map publication, run replacement.
The comparison policy distinguishes same-source controls, historical changes and full checkpoints.
Related mechanisms: R100.