roundtrip-volume-residual

The groupant beside tools/roundtrip/src/vol.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.

Facts

Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.

Components

component	label	where
approximant	partial	approximant
ast	partial	`syntax.json`
composition	partial	composition
cost	symbolic source derived	invariant-and-cost
descriptant	present	descriptant
invariant	partial	invariant-and-cost
tests	executed bounded checks	tests

Obernants

The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.

id	type	label	where
`behavior_complement`	behavior_complement	partial source derived model	behavior_complement
`reverse_reconstruction`	reverse_reconstruction	partial source derived model	reverse_reconstruction
`gap_coordinates`	gap_coordinates	partial source derived model	gap_coordinates
`utf8_copy`	utf8_copy	partial source derived model	utf8_copy
`history_tie`	history_tie	partial source derived model	history_tie
`mark_precondition`	mark_precondition	partial source derived model	mark_precondition

Parts

Model text

descriptant

Description and epoch memory

txt_volume preserves paragraphs and layout, with_marks inserts markup at byte coordinates. segment aligns tokens against text then cut partitions punctuation boundaries; residual records noncanonical gaps/tails and charges layout/markup. decode_blocks combines canonical spaces and residual overrides, volume_text reapplies pieces/marks. Copier scans next/recent/head/tail candidates, picks strictly cheaper copy, verifies decode, updates counters/history.

Epoch 2026-10-31

Prospective model retained externally before edits. Existing production bytes preserved; only bounded inline tests appended to six owned files. Models distinguish byte reconstruction with residual from semantic understanding and persistent learning. Finite tests and compiled mutants support selected boundaries only. Source inspection identified noninjective projections and explicit admissibility restrictions; no bug repair or performance claim.

Combiner input is this source snapshot, syntax projection, models, costs and retained receipts. Proposed next epoch: target the stated unexecuted branches with bounded witnesses before expanding any claim. AST remains partial, macros opaque; no name resolution or proof.

approximant

Forward relation

Domain: Valid Piece indices, Sent vectors and nonempty sentence forms; mark/gap UTF-8 boundaries; copy indices and pre/suf within earlier strings; representable counts and finite symbolic bit sums. Annotator and file readers unexecuted.

No executable percentage surrogate is supplied: these categorical codec/effect observations have no justified lossy metric. Future caps are 1/2/5/10% only after defining metric, zero behavior and differential reference.

composition

Local composition

Children scope selected internal mechanisms by byte ranges; remaining branches are covered only by the parent partial model. Their costs are included in parent costs, not added again. Shared values and caller order are those named above; sibling fragments are tagged independent where no direct call is named.

catalog

Source-bound typed models

Each section is a partial source-derived relation on the bound snapshot and declared domain; finite checks are falsification evidence, not a universal proof. Observation horizon is one call unless history is explicitly named.

behavior_complement

Residual coordinate override wins over canonical gaps; metadata always charged; Given/Conllu/FrTable literals excluded here. Copier never selects equal-cost copy over current candidate; returned code costs <=whole flag+literal bits on admitted domain.

Domain and held state: Valid Piece indices, Sent vectors and nonempty sentence forms; mark/gap UTF-8 boundaries; copy indices and pre/suf within earlier strings; representable counts and finite symbolic bit sums. Annotator and file readers unexecuted.