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

The groupant beside prag/src/rules.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:** [`prag/src/rules.rs`](https://github.com/ElamurAI/mova-free/blob/main/prag/src/rules.rs)
- **source SHA-256:** `ba82334c7c91aaaf…`
- **covers:** select_rules(text,mode)=[] for off; otherwise stable filter parse_rules(text), keeping accepted or (mode=proposed and status=proposed). active returns an override unchanged first; absent override, OnceLock captures first environment/file selection with embedded fallback. Only pure selection is executed. (bytes 22280–23621)
- **part of:** [prag-rules-codec](https://md.groupants.elamur.ai/free/en/mova/prag/src/rules.rs.groupant/codec.groupant/)
- **repository folder:** [`prag/src/rules.rs.groupant/codec.groupant/selection.groupant`](https://github.com/ElamurAI/mova-free/tree/main/prag/src/rules.rs.groupant/codec.groupant/selection.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 source model | [forward](#forward) |
| **ast** | partial | `../../syntax.json` |
| **composition** | partial source model | [composition](#composition) |
| **cost** | partial source model | [cost](#cost) |
| **descriptant** | partial source model | [epoch-memory](#epoch-memory) |
| **invariant** | partial source model | [invariant](#invariant) |
| **tests** | partial source model | [checks](#checks) |

## 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 |
|---|---|---|---|
| `prag-rules-codec-selection-behavior-complement` | behavior_complement | partial source model | [behavior-complement](#behavior-complement) |
| `prag-rules-codec-selection-reverse-reconstruction` | reverse_reconstruction | partial source model | [reverse-reconstruction](#reverse-reconstruction) |
| `prag-rules-codec-selection-specialization` | status_filter | partial source model | [specialization](#specialization) |

## Model text


### forward
select_rules(text,mode)=[] for off; otherwise stable filter parse_rules(text), keeping accepted or (mode=proposed and status=proposed). active returns an override unchanged first; absent override, OnceLock captures first environment/file selection with embedded fallback. Only pure selection is executed.

### invariant
Duplicates and file order survive. Unknown modes select accepted only; rejected/unknown statuses never survive. Override intentionally bypasses filter; environment changes after cached load do not recompute.

### cost
O(B+L*C) parse plus O(L) filtering; off O(1). Cache locking, IO and scheduling unmeasured.

### behavior-complement
For statuses [accepted,proposed,rejected,other,accepted] and IDs [z,a,b,c,z], U candidate selected IDs excludes off != [], default != [z,z], proposed != [z,a,z]. This does not constrain overrides.

### reverse-reconstruction
Selected [z,z] permits arbitrarily many rejected/unknown rows between them and different unknown modes. Off collapses every text to []; retain all compatible texts in inverse.

### specialization
File position is priority, not ID sort/dedup. Fixture deliberately contains z before a and repeated z.

### composition
Codec feeds selection without reordering. Sites and action-dependent atoms share the pre-rule Read; ordered action fold sees evolving state, then deletion remaps coordinates. Selection nested in codec retains status distinctions. Exact byte scopes constrain composition; no child alone proves the parent.

### checks
Ten rules::wave15_models tests, tiny supplied fixtures only; two debug and two release passes with identical named outcomes. File-root receipts.md retains hashes. Finite catalogs, nine transfer states and sixteen deletion subsets; compiled production vacancy-guard mutant fails finite_transfer_and_drop_relations.

### epoch-memory
2026-10-30: first rules tree. Review predicted unchanged valid-site transitions and O(1) validation before O(Read bytes) cloning. Old invalid_direct_sites_are_no_change failed because absent Drop returned Some; seven other initial tests passed. Repair rejects absent coordinates/unaligned reads. select_rules exposes the existing production filter; no selection policy change or speedup claimed.

### limitations
Partial syntax, no expanded macros or semantic AST proof. No live parser, teacher, corpus, environment mutation, override or cache acquisition in tests. Empty verbs/entities avoid lexical matching acquisition; populated entity tests use direct actions. Token creation, full lexical/ancestry/action branches, IO/cache lifetime and all multi-site interactions remain unexecuted. Public atoms/drop_frames still require valid coordinates/alignment.