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

The groupant beside tools/mathlib/src/http.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:** [`tools/mathlib/src/http.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/mathlib/src/http.rs)
- **source SHA-256:** `3df63f2ba1d7bcdb…`
- **covers:** hex emits two lowercase digits per byte; encode emits unreserved ASCII or uppercase %HH per byte; civil maps bounded signed day offsets by Euclidean Gregorian eras. (bytes 5828–7355)
- **part of:** [mathlib-http](https://md.groupants.elamur.ai/free/en/mova/tools/mathlib/src/http.rs.groupant/)
- **repository folder:** [`tools/mathlib/src/http.rs.groupant/codecs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/mathlib/src/http.rs.groupant/codecs.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 | [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 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.

| id | 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) |
| `byte_length` | byte_length | partial source derived model | [byte_length](#byte-length) |
| `escape_idempotence` | escape_idempotence | partial source derived model | [escape_idempotence](#escape-idempotence) |
| `era_boundary` | era_boundary | partial source derived model | [era_boundary](#era-boundary) |
| `calendar_projection_scope` | calendar_projection_scope | partial source derived model | [calendar_projection_scope](#calendar-projection-scope) |

## Model text


### descriptant

#### mathlib-http-codecs

hex emits two lowercase digits per byte; encode emits unreserved ASCII or uppercase %HH per byte; civil maps bounded signed day offsets by Euclidean Gregorian eras.

##### Epoch 2026-10-31

Prospective model retained before changes. Existing production bytes are preserved; additions are bounded inline tests. Nine source groupants expose ingestion and routing boundaries; typed children bind exact source bytes and reuse their parent syntax projection. Native tests run twice per profile; behavior mutants run as compiled source changes and exact bytes are restored before positive checks.

Important retained observation: network-looking helpers are not all pure (DNS inside github_host and books build); selection deliberately excludes those effects. Mixed-format manifest order is not deterministic, and error paths do not imply rollback.

No network/DNS/download, real catalog/corpus/model/teacher or database execution. Effect paths are source-derived; finite helper tests are not universal verification. No executable percentage surrogate or speed claim; future caps require metric/domain/reference and remain 1/2/5/10%.

### approximant

#### Forward relation

hex emits two lowercase digits per byte; encode emits unreserved ASCII or uppercase %HH per byte; civil maps bounded signed day offsets by Euclidean Gregorian eras.

Model observations include returns, retained state and ordered partial effects; on external failures the successful-prefix relation replaces a total-function claim.

### catalog

### behavior_complement

Subject: mathlib-http-codecs, source SHA-256 3df63f2ba1d7bcdb4f0bf02fa7c7a1f0feb5817d22f7409456945ccf6a57aa32; finite transition observation.

Canonical encode output never contains literal space, slash or non-ASCII; hex contains only lowercase ASCII hexadecimal characters.

Domain: stated source predicates, bounded inputs and available resources; arithmetic assumptions and external effect gaps as in the invariant. Operator is the stated relation/projection; complement is a source-derived inner exclusion, reverse retains compatible antecedents. Other views are source-derived partial constraints, not inverse laws.

Evidence: tests.md identifies executed helpers and unexecuted paths. No universal guarantee follows from the finite fixtures.

### reverse_reconstruction

Subject: mathlib-http-codecs, source SHA-256 3df63f2ba1d7bcdb4f0bf02fa7c7a1f0feb5817d22f7409456945ccf6a57aa32; finite transition observation.

hex decode and canonical percent decode uniquely recover bytes on their image. Civil inverse determines day number only for valid Gregorian triples in the bounded nonoverflowing domain; utc_now formatting loses subsecond precision.

Domain: stated source predicates, bounded inputs and available resources; arithmetic assumptions and external effect gaps as in the invariant. Operator is the stated relation/projection; complement is a source-derived inner exclusion, reverse retains compatible antecedents. Other views are source-derived partial constraints, not inverse laws.

Evidence: tests.md identifies executed helpers and unexecuted paths. No universal guarantee follows from the finite fixtures.

### byte_length

Subject: mathlib-http-codecs, source SHA-256 3df63f2ba1d7bcdb4f0bf02fa7c7a1f0feb5817d22f7409456945ccf6a57aa32; finite transition observation.

UTF-8 é has two encoded bytes and output %C3%A9 length six; counting code points would give a wrong cost/output-length model.

Domain: stated source predicates, bounded inputs and available resources; arithmetic assumptions and external effect gaps as in the invariant. Operator is the stated relation/projection; complement is a source-derived inner exclusion, reverse retains compatible antecedents. Other views are source-derived partial constraints, not inverse laws.

Evidence: tests.md identifies executed helpers and unexecuted paths. No universal guarantee follows from the finite fixtures.

### escape_idempotence

Subject: mathlib-http-codecs, source SHA-256 3df63f2ba1d7bcdb4f0bf02fa7c7a1f0feb5817d22f7409456945ccf6a57aa32; finite transition observation.

encode is not idempotent: encoding %2F gives %252F. It is a value encoder, not a normalizer of already-escaped URLs.

Domain: stated source predicates, bounded inputs and available resources; arithmetic assumptions and external effect gaps as in the invariant. Operator is the stated relation/projection; complement is a source-derived inner exclusion, reverse retains compatible antecedents. Other views are source-derived partial constraints, not inverse laws.

Evidence: tests.md identifies executed helpers and unexecuted paths. No universal guarantee follows from the finite fixtures.

### era_boundary

Subject: mathlib-http-codecs, source SHA-256 3df63f2ba1d7bcdb4f0bf02fa7c7a1f0feb5817d22f7409456945ccf6a57aa32; finite transition observation.

civil(-1)=1969-12-31 and civil(11017)=2000-03-01; leap handling follows century/400-year terms. Fixtures constrain boundaries, not all i64 arithmetic.

Domain: stated source predicates, bounded inputs and available resources; arithmetic assumptions and external effect gaps as in the invariant. Operator is the stated relation/projection; complement is a source-derived inner exclusion, reverse retains compatible antecedents. Other views are source-derived partial constraints, not inverse laws.

Evidence: tests.md identifies executed helpers and unexecuted paths. No universal guarantee follows from the finite fixtures.

### calendar_projection_scope

civil's output is a date triple; utc_now computes days=secs/86400 and rem=secs%86400, then appends whole-second clock fields. Different subsecond instants share output; civil itself has no clock or filesystem effects. Extreme i64 offsets can overflow before era decomposition and are outside the stated domain.

Subject and source identity: manifest.json. Domain: scoped forward/invariant; relation is source-derived and partial. Evidence: tests.md distinguishes actual checks from unexecuted effect paths; finite fixtures do not prove all inputs.

### tests

#### Bounded evidence

Selected actual source checks:

- mathlib::http::tests::encodes_and_dates
- mathlib::http::wave33::byte_codecs_and_civil_boundaries

These checks are file-level evidence; fragment branches not reached by these names remain source-derived.

External wave33 mathlib receipt retains native-commands.json, numeric statuses, raw debug/release logs, sorted exact outcomes, mutation logs and original/restored hashes. Seventeen named checks pass twice per profile; six production behavior mutants reject in both profiles, with restored positives. Source syntax is regenerated twice after formatting and compared byte-for-byte. Structural validation tests bindings, not Rust semantics.

No network/DNS/download, real catalog/corpus/model/teacher or database execution. Effect paths are source-derived; finite helper tests are not universal verification. No executable percentage surrogate or speed claim; future caps require metric/domain/reference and remain 1/2/5/10%.

### invariant-and-cost

#### Invariant and cost

##### Invariant

Hex output length=2n. Encoded output length=n+2k for k non-unreserved bytes. Empty input maps empty for both codecs.

##### Cost

O(input bytes) codecs; civil fixed arithmetic work, subject to nonoverflowing signed offsets.

##### Domain and gaps

No network/DNS/download, real catalog/corpus/model/teacher or database execution. Effect paths are source-derived; finite helper tests are not universal verification. No executable percentage surrogate or speed claim; future caps require metric/domain/reference and remain 1/2/5/10%.