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

The groupant beside world/build.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
- **status:** partial source bound model
- **source:** [`world/build.rs`](https://github.com/ElamurAI/mova-free/blob/main/world/build.rs)
- **repository folder:** [`world/build.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/world/build.rs.groupant)

> **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 or representation | [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.

| relation | 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) |

## Model text


### Descriptant

The build script of the `world` crate. It decides whether the legacy central manuals (`state::CENTRAL_MANUALS`,
feature `worlds`, also enabled by `peta`) are compiled in: only when the feature is on and the folder
`peta/world/legacy/worlds` exists beside the crate. It exists so that a public checkout, which has no `peta/`,
compiles with `--all-features` (2026-11-05).

### Approximant

Forward relation: F(feature_worlds, dir_exists) emits `rustc-check-cfg=cfg(mova_legacy_worlds)` and
`rerun-if-changed=build.rs` always; then

- feature off: nothing more;
- feature on, folder present: `rerun-if-changed=<folder>` and `rustc-cfg=mova_legacy_worlds`;
- feature on, folder absent: one `cargo:warning` naming the absent folder, no cfg.

Composition: `cfg(mova_legacy_worlds)` selects the `include_str!` table of `state.rs` (otherwise the empty table)
and the test `nerves::time_words_reach_the_world_of_time`. The freesync export treats this cfg as false
(`PRIVATE_BUILD_CFGS`), since the export has no `peta/`.

### Behavior complement

It never reads the manuals, never checks that the 33 named files exist (a partial folder fails later at
`include_str!`), never sets the cfg without the feature, and never fails the build. Watching a directory notices
added or removed entries, not edits inside files (cargo's directory rule).

### Reverse reconstruction

From the emitted cfg one recovers (feature on ∧ folder present); from its absence only (feature off ∨ folder
absent), which the warning disambiguates: a warning means feature on and folder absent. The folder's contents are
not recoverable.

### Invariant and cost

Invariant: `mova_legacy_worlds` ⇒ feature `worlds` ∧ the folder existed when the script ran. Cost: one environment
lookup and one `stat`; O(1).

### Tests

Compiled with and without the folder: `cargo check -p world --features peta` in the private checkout (manuals in),
and `cargo check --all-features` on the public export (warning, empty table), 2026-11-05. No unit test: the script's
inputs are cargo's environment and the file system.

## Provenance

- **source SHA-256:** `5b52e7120347c66b…`
- **repository commit:** `d2474dc36e44`