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

The groupant beside tools/nightingale/src/model.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:** [`tools/nightingale/src/model.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/nightingale/src/model.rs)
- **repository folder:** [`tools/nightingale/src/model.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/nightingale/src/model.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 | [Forward approximant](#forward-approximant) |
| **Ast** | partial | `syntax.json` |
| **Composition** | partial | [Composition](#composition) |
| **Cost** | partial | [Cost](#cost) |
| **Descriptant** | present | [Descriptant](#descriptant) |
| **Invariant** | partial | [Invariant](#invariant) |
| **Tests** | finite evidence | [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

A loaded model: per-label counts, the interpolated absolute-discounting bigram language model with a character spelling back-off, held-out bits per token, trends and the varieties' composed counts. Source: `tools/nightingale/src/model.rs`.

### Forward approximant

load: meta and body hash checked; pooled unigrams, left-context discount mass, spelling model over kept types; p1, p2, bits, bits_per_token; variety(kind, payload, label) = c_std * 2^shift.

### Invariant

P2 sums to one over the vocabulary for a seen context; the body must hash to its meta; deltas must belong to the lineage.

### Cost

Load O(records) memory (2.2 GB peak for the 6.4 M-record English probe); a token O(1) hash lookups.

### Composition

Parent: nightingale.

### Behavior complement

Never writes; an unknown label counts 0. Evidence status: source-derived model with finite checks, not a proof.

### Reverse reconstruction

The model is a function of its parts (lineage); counts are exact, probabilities derived.

### Tests

#### Checks

tests/model.rs: more text fewer bits; the shuffled control; measure on the probes.
These are finite fixtures and measurements; not a proof.

## History


#### 2026-11-06 · document

##### Epoch 2026-11-06

First model, written with the source (the Nightingale: one per language under the Eel; a standard naturalness model with variety deltas).

## Provenance

- **source SHA-256:** `16a98f1ebb98daa3…`
- **repository commit:** `2e25d7bfae9a`