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

This page as HTML: <https://groupants.elamur.ai/free/en/mova/tools/treestore/src/codec.rs.groupant/>

# treestore-codec

The groupant beside tools/treestore/src/codec.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/treestore/src/codec.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/treestore/src/codec.rs)
- **repository folder:** [`tools/treestore/src/codec.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/treestore/src/codec.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` |
| **Composition** | partial | [Composition](#composition) |
| **Cost** | symbolic source derived | [Invariant](#invariant) |
| **Descriptant** | present | [Descriptant](#descriptant) |
| **Invariant** | partial | [Invariant](#invariant) |
| **Tests** | executed 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.

| 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 field codecs: an annotated article's five text fields (Markdown, sentence rows, CoNLL-U, frames, pragmatics) as
typed columns. Each coded field is decoded back at write time and kept in the envelope as written if any byte
differs, so the round trip is lossless by construction. Epoch 2026-11-06: on tier-1 shards 00005/00050/00099 and 1 272
random articles every field of every record was taken by its codec (0 kept raw).

### Approximant

Forward, per article, in field order (each field may use the earlier ones as context):
- Markdown → `md` raw.
- sentence rows → header id; count; prefix literal; per row a flag byte (irregular id/n, section change, item, block
  literal, text literal), block delta, and the text as (offset from the cursor, length) into the Markdown.
- CoNLL-U → per tree: row delta, flags (text ≠ row text, last token SpaceAfter=No); per whitespace chunk of the text
  0 when the predicted split (frozen rule + model exceptions) is right, else the token byte lengths; structure
  symbols (shape ids or fragments); per token, escaped (tag, rel, head) and the lemma edit-script id (or literal).
- frames → header, count, per row: row delta, frame count, pieces as table id / reference to a lemma or form of the
  sentence (4 kinds per token) / literal.
- pragmatics → header, count, per row: row delta, the six labels as one tuple id, confidences as hundredths.
Measured 2026-11-06 (shard 00050, final model): structure 2.0 MB for 2.82 M tokens (≈5.7 bits/token), lemma 0.49 MB
(1.4 bits/token), splits 0.06 MB, text offsets 0.17 MB.

### Invariant

For every record r: decode(encode(r)) = r byte for byte. Per field: coded ⇒ dec_field(enc_field(v)) = v and all its
streams are used up (checked in enc_field); otherwise the field stays in the envelope. MISC/SpaceAfter, `# sent_id`,
row ids and sentence numbers are derived, not stored. Cost: O(bytes) per field plus O(chunks·chunk length) for the
split predictor and O(rows·distance) for the text search in the Markdown (the cursor makes it linear for in-order
sentences).

### Composition

Uses cols (streams), json (members, escaping), model (tables, shapes, fragments, split exceptions). Called by
store::encode_group and Shard::decode. The frames codec depends on the CoNLL-U string (decoded or kept), the tree and
pragmatics codecs on the sentence rows, the sentence codec on the Markdown.

### Behavior complement

Does not interpret meaning, does not normalise anything, does not code CoNLL-U with multiword ranges, empty nodes,
DEPS ≠ `_`, MISC other than SpaceAfter=No, forms that do not tile the `# text` by single spaces, or rows whose
column counts differ (those fields stay raw). Confidences are lossless (no quantisation).

### Reverse reconstruction

decode is the exact inverse on coded fields given the same model; a coded field is recoverable only with the model
whose tables, exceptions and fragments made it (the store checks the model id). Frame references are recoverable only
from the decoded tree of the same sentence.

### Tests

Integration test `tests/roundtrip.rs` (synthetic records in three structure modes, a raw-kept CoNLL-U field, sentence
views); the real-data gate is `treestore verify` (byte equality of every record with the source).

## Provenance

- **source SHA-256:** `fb031daa45eca1f7…`
- **repository commit:** `f55191f0d47f`