---
title: "roundtrip-pipeline-drop — Mova code model"
description: "Mova code model of tools/roundtrip/src/pipeline.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/tools/roundtrip/src/pipeline.rs.groupant/drop.groupant/"
---
Elamur: [Mova](https://md.mova.elamur.ai/free/en/) · [Dictionary](https://md.dictionary.elamur.ai/free/en/) · [Research](https://md.research.elamur.ai/free/en/) · **Groupants**

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# roundtrip-pipeline-drop

The groupant beside tools/roundtrip/src/pipeline.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

- **kind:** groupant_fragment
- **status:** partial source bound model
- **source:** [`tools/roundtrip/src/pipeline.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/roundtrip/src/pipeline.rs)
- **source SHA-256:** `88be3b618dd82841…`
- **covers:** Dropped-class head repair (bytes 2040–2750)
- **part of:** [roundtrip-pipeline](https://md.groupants.elamur.ai/free/en/mova/tools/roundtrip/src/pipeline.rs.groupant/)
- **repository folder:** [`tools/roundtrip/src/pipeline.rs.groupant/drop.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/roundtrip/src/pipeline.rs.groupant/drop.groupant)
- **repository commit:** `855da7bd4a7b`

> **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](#approximant) |
| **ast** | partial | `../syntax.json` |
| **cost** | partial | [invariant-and-cost](#invariant-and-cost) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant-and-cost](#invariant-and-cost) |
| **tests** | bounded checks | [tests](#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](#behavior-complement) |
| `reverse_reconstruction` | reverse_reconstruction | partial source derived model | [reverse_reconstruction](#reverse-reconstruction) |
| `head_repair` | head_repair | partial source derived model | [head_repair](#head-repair) |
| `scope_precondition` | scope_precondition | partial source derived model | [scope_precondition](#scope-precondition) |
| `resource_boundary` | resource_boundary | partial source derived model | [resource_boundary](#resource-boundary) |
| `observation_projection` | observation_projection | partial source derived model | [observation_projection](#observation-projection) |

## Model text


### descriptant

#### Dropped-class head repair

2026-10-31 epoch: source scope bytes [2040,2750); Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root.

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%.

### approximant

#### Dropped-class head repair

Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root.

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.

### catalog

### behavior_complement

Subject: roundtrip-pipeline-drop, source hash 88be3b618dd828411c1e6633432af60ba9fa905429b55cff88fbc31b5ae721da, transition observation.

For Dropped-class head repair, excluded transitions violate the stated scoped rule: Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root. This is an inner source-derived exclusion under the domain, not a complement of arbitrary unseen runtime behavior.

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.

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.

Status: partial source-derived model.

### reverse_reconstruction

Subject: roundtrip-pipeline-drop, source hash 88be3b618dd828411c1e6633432af60ba9fa905429b55cff88fbc31b5ae721da, transition observation.

Fix outputs and post-state of drop; compatible antecedents are all scoped inputs/pre-state satisfying: Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root. Fields outside this byte scope are held fixed; discarded fields remain ambiguous.

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.

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.

Status: partial source-derived model.

### head_repair

Subject: roundtrip-pipeline-drop, source hash 88be3b618dd828411c1e6633432af60ba9fa905429b55cff88fbc31b5ae721da, transition observation.

drop_class renumbers survivors and follows removed-head chain with n-step guard. Valid head coordinates required; cycle of removed nodes falls back root.

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.

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.

Status: partial source-derived model.

### scope_precondition

Subject: roundtrip-pipeline-drop, source hash 88be3b618dd828411c1e6633432af60ba9fa905429b55cff88fbc31b5ae721da, transition observation.

Dropped-class head repair requires the coordinate/state assumptions of this fragment; inspect its exact byte range. Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root. Invalid arbitrary state is outside the reconstruction law.

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.

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.

Status: partial source-derived model.

### resource_boundary

Subject: roundtrip-pipeline-drop, source hash 88be3b618dd828411c1e6633432af60ba9fa905429b55cff88fbc31b5ae721da, transition observation.

Dropped-class head repair: allocations/clones and recursion/scans within this scope are retained. Parent cost bound is conservative for this subroutine: groups O(n) singleton storage or O(1) Block. drop_class O(n^2) worst-case ancestor walking, O(n) vectors. run cost sums segmentation, annotation, frame realization, alignments, world passes and text diffs; retained intermediate payload is proportional to all generated representations, not streaming constant memory.

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.

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.

Status: partial source-derived model.

### observation_projection

Subject: roundtrip-pipeline-drop, source hash 88be3b618dd828411c1e6633432af60ba9fa905429b55cff88fbc31b5ae721da, transition observation.

Observe only outputs/state produced by Dropped-class head repair, holding caller state fixed. Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root. Downstream aggregation is not an injective observation of this scope.

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.

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.

Status: partial source-derived model.

### tests

#### Scoped evidence

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.

Coverage is limited to this fragment's reached branches; parent tests do not prove every scoped branch.

### invariant-and-cost

#### Scoped invariant and cost

Survivor indices are compressed, removed ancestors skipped with bounded guard, and head0 remains virtual root.

groups O(n) singleton storage or O(1) Block. drop_class O(n^2) worst-case ancestor walking, O(n) vectors. run cost sums segmentation, annotation, frame realization, alignments, world passes and text diffs; retained intermediate payload is proportional to all generated representations, not streaming constant memory.

The parent bound is conservative; unrelated parent effects are excluded from this fragment.