---
title: "world-store-coupling — Mova code model"
description: "Mova code model of world/src/store.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/world/src/store.rs.groupant/selection.groupant/coupling.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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# world-store-coupling

The groupant beside world/src/store.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 derived instance
- **source:** [`world/src/store.rs`](https://github.com/ElamurAI/mova-free/blob/main/world/src/store.rs)
- **source SHA-256:** `6801677c4f17273e…`
- **covers:** world-store-coupling (bytes 23187–25941)
- **part of:** [world-store-selection](https://md.groupants.elamur.ai/free/en/mova/world/src/store.rs.groupant/selection.groupant/)
- **repository folder:** [`world/src/store.rs.groupant/selection.groupant/coupling.groupant`](https://github.com/ElamurAI/mova-free/tree/main/world/src/store.rs.groupant/selection.groupant/coupling.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 | [Forward](#forward) |
| **ast** | partial | `../../syntax.json` |
| **cost** | symbolic unmeasured | [Cost](#cost) |
| **descriptant** | present | `model.md` |
| **invariant** | partial | [Invariant](#invariant) |
| **tests** | bounded evidence | `../../model.md#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 |
|---|---|---|---|
| `nonbehavior` | behavior_complement | partial source derived model | [nonbehavior](#nonbehavior) |
| `antecedents` | reverse_reconstruction | partial source derived model | [antecedents](#antecedents) |
| `positional-coupling` | dependency_closure | partial source derived model | [positional-coupling](#positional-coupling) |
| `rank-boundary` | counterfactual | partial source derived model | [rank-boundary](#rank-boundary) |

## Model text


### descriptant

## coupling

### Forward

Sampling advances a seed-derived xorshift stream once per ordered candidate, combines the state with ID salt, sorts key/ID pairs, takes k and sorts retained IDs. Filtering first changes stream positions and competitors.

### Invariant

Sample output is sorted, unique and a subset of duplicate-free input candidates, of length min(k,n). Changed eligibility can change unchanged output membership. Reverse fibers retain candidate ordering and losing candidates.

### Cost

O(n) pair allocation and O(n log n) sorting. This is the same sampling work modeled by the parent and must not be added again.

### Epoch memory

2026-10-29: The removed-ID witness disproved that exact eligibility deltas suffice for sampled carry. Fixed-seed determinism does not imply candidate independence.

### catalog

## world-store-coupling

Source SHA-256 6801677c4f17273e615090a790f2e4018387ca5d006aab899bafda09f01b24d9. Conditional models over successful finite operations; I/O failure, malformed offsets and changing dependency state are excluded unless stated. Algebra is exact only for its declared abstract relation. Source correspondence remains bounded.

### nonbehavior

Type: behavior_complement.

Universe: ordered duplicate-free candidate vectors, valid k and seed, and output vectors. Candidate inner complement includes sampled outputs longer than min(k,n), unsorted outputs, duplicate outputs, and IDs absent from candidates. This is a conditional source model of the sample stage, not the complement of the full query.

### antecedents

Type: reverse_reconstruction.

Fix k and seed. A sampled observation Y has every ordered candidate vector C whose first min(k,|C|) pairs in sorted(key(C position,seed) xor id salt,id) have numerically sorted selected IDs equal to Y as compatible antecedents. Different candidate orders and losing candidates remain possible. No unique inverse; k=0 maps every candidate vector to empty.

### positional-coupling

Type: dependency_closure.

The xorshift stream advances per candidate position. Removing one eligible ID changes ranks of later unchanged IDs as well as competition for k slots. Changed-ID dictionaries therefore do not bound output membership changes. Historical witness eligible [0,1,2] to [0,2], C={1}, pred>=1 sample=1/2 gives old [1], fresh [2], legacy merge []; repaired load must return [2].

### rank-boundary

Type: counterfactual.

Hold query order and seed fixed, replace legacy delta-merge by complete target selection for stale sampled queries. Output equals F even if O\C differs from F\C. This intervention fixes candidate coupling but does not validate feature extraction, mutable same-hash indexes or forged stable stamps. Oracle compares repaired witness and rejects historical empty result.