roundtrip-lib

The groupant beside tools/roundtrip/src/lib.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`
cost	partial	invariant-and-cost
descriptant	present	descriptant
invariant	partial	invariant-and-cost
tests	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
`environment_fallback`	environment_fallback	partial source derived model	environment_fallback
`path_join`	path_join	partial source derived model	path_join
`export_join`	export_join	partial source derived model	export_join
`model_load_gap`	model_load_gap	partial source derived model	model_load_gap

Model text

descriptant

roundtrip-lib

2026-10-31 prospective epoch retained externally before edits.

Publishes layer modules and conditionally test module. model_path reads MOVA_DATA; absent or non-Unicode value falls back to HOME plus /mova-data, then appends en/models/en.bin.

No annotator/model loading, live corpus, full suite, teacher, GPU or persistent-learning evidence. No executable percentage surrogate: categorical codecs/effects need a useful metric before future caps 1/2/5/10%.

Exact recovery with residual is a diagnostic codec observation. It is not evidence of normal generative equivalence, semantic understanding or persistent learning. Production source is preserved; only isolated tests are appended where needed.

approximant

Forward relation

Publishes layer modules and conditionally test module. model_path reads MOVA_DATA; absent or non-Unicode value falls back to HOME plus /mova-data, then appends en/models/en.bin.

Domain: bounded synthetic values, valid source-specific coordinates, nonoverflowing counts, available allocation; fixed environment controls. Relations are source-derived partial models with finite checks, not universal proofs.

Composition

Source children delimit real function scopes, sharing syntax. Real pipeline joins R4 frame reconstruction to Realizer then R3 tree script and R2 token decode; report consumes aggregated tally. Independent path/CLI branches are not fictitious codec callers.

catalog

behavior_complement

Subject: roundtrip-lib, source hash 366f25c83a674bd1917578e2c985b4c0585f02a1d3fa53e4101c7e9d0a895606; transition observation.

model_path performs no existence check, file open, model load or directory creation. Exports do not themselves run a roundtrip.

Evidence: external wave32 rt_core receipt includes native-commands.json, exact named outcomes twice debug/twice release, raw status/log files, compiled production controls with byte restoration and paired syntax. Only named synthetic helpers execute; model_path/export and live CLI paths have representation/source evidence.