Self‑Healing Localization Layer

Automatic, self‑maintaining localization for any Python project

Author: Tuomas Lähteenmäki
License: MIT
Version: 0.1.7

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Overview

Self‑Healing Localization Layer (SHL) is a lightweight, dependency‑free Python library that eliminates missing translations forever.

It provides:

• Automatic creation of missing language files .
• Automatic creation of missing keys.
• Fallback to a base language (default: English).
• Unified support for both UI text and optional AI prompt templates.
• GLFM integration for 7,900+ languages with BCP-47 tags and fallback chains.

This library is designed to be dropped into any project — from small scripts to full applications — and it will maintain localization files automatically as the project grows.

• No more manual JSON editing.
• No more "missing translation" errors.
• No more incomplete language packs.

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Key Features

Self‑Healing UI Localization

• Missing language files are created automatically.
• Missing keys are added on the fly.
• Base language is used as fallback.
• Region subtags preserved: zh-TW, pt-BR get their own files.

Self‑Healing AI Prompt Template Localization

Large Language Model (LLM) applications often require localized prompt templates in addition to localized UI text. SHL manages both through the same self-healing localization engine.

• Missing template files are generated automatically.
• Base templates are copied as fallback.
• Missing template keys are added automatically.
• Same region subtag support as UI localization.

Unified High‑Level Engine

The LocalizationEngine ties everything together:

• Ensures languages exist.
• Synchronizes all languages with the base language.
• Provides a single interface for UI text and prompt templates.
• Optional GLFM language validation with BCP-47 tags.

Zero Dependencies

Pure Python. Works everywhere.

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What's New in v0.1.7

• GLFM Integration – 7,900+ languages with ISO 639, BCP-47, fallback chains
• Region Subtag Support – zh-TW, pt-BR get their own files
• Dynamic Language Detection – LibreTranslate /languages API with 24h cache
• Environment Variable Support – .env file for API keys and configuration
• Improved Error Handling – Clear messages for 403, 429 API errors
• Language Code Normalization – Automatic en-US → en conversion
• MyMemory Email Support – Optional email for 30k words/day limit
• 106 Unit Tests – Full coverage for all components

All v0.1.6 features included:

• AI Translations – MyMemory + LibreTranslate fallback system
• Translation Cache – Automatically reduces API calls
• Corrupted File Protection – Automatic .bak backup creation
• Unified Logging – error.log with configurable levels
• Dynamic Language Switching – set_language() on the fly
• Key Validation – Type, emptiness, and whitespace checks
• Legacy File Migration – Automatic lang_xx.json → xx.json conversion

Installation

Stable

Stable version available via PyPI (v0.1.5):

pip install self-healing-localization

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Test

Test version available via TestPyPI preview (v0.1.7):

pip install -i https://test.pypi.org/simple/ self-healing-localization==0.1.7

Environment Variables (.env)

Create a .env file in your project root (optional):

MYMEMORY_EMAIL=your@email.com
LIBRETRANSLATE_API_KEY=your-api-key
LIBRETRANSLATE_URL=https://translate.argosopentech.com

Quick Start

1. Basic UI Localization

Initialize the engine and start retrieving text. If the key doesn't exist, it is added to your JSON files automatically.

from shl.engine import LocalizationEngine

# Initialize the engine (e.g., set user language to Finnish)
engine = LocalizationEngine(lang_code="fi", base_lang="en")

# Retrieve UI text. If 'welcome_msg' is missing, it's created with the default value.
title = engine.ui_text("welcome_msg", "Welcome to the App!")
print(title)

2. Retrieve UI text

title = engine.ui_text("app_title", "My Application")

If "app_title" does not exist in locales/en.json, it will be added automatically.

3. Retrieve prompt templates

summary_prompt = engine.template("summary_short", "Summarize the text:")

If prompts/fi.json does not exist, it will be created automatically using prompts/en.json as the base.

4. AI Prompt Templates

Keep your AI prompts localized just like your UI strings.

# Retrieve a localized prompt template
prompt = engine.template("summarize_task", "Please summarize the following text:")

5. Dynamic Language Switching (New in v0.1.6)

Switch languages on the fly without restarting your application.

# Start in English
engine = LocalizationEngine(lang_code="en")

# Switch to Finnish
engine.set_language("fi")
print(engine.ui_text("greeting", "Hello!"))  # "Hei!" (AI-translated)

# Switch to Swedish
engine.set_language("sv")
print(engine.ui_text("greeting", "Hello!"))  # "Hej!" (AI-translated)

6. Region Subtag Support (New in v0.1.7)

# Brazilian Portuguese and European Portuguese in separate files
engine = LocalizationEngine(lang_code="pt-BR")  # → pt-br.json
engine = LocalizationEngine(lang_code="pt-PT")  # → pt-pt.json

# Traditional and Simplified Chinese in separate files
engine = LocalizationEngine(lang_code="zh-TW")  # → zh-tw.json
engine = LocalizationEngine(lang_code="zh-CN")  # → zh-cn.json

7. Synchronize All Languages

Sync all keys from the base language to the current language.

engine.sync()

8. Using GLFM Language Validation

engine = LocalizationEngine(
    lang_code="fi",
    glfm_path="data/unified_languages.json"
)

stats = engine.get_stats()
print(stats["glfm_loaded"])  # True
print(stats["lang_code"])    # fi

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Project Structure

The library follows a modular design to keep the core logic separate from your application code:

self-healing-localization/
│
├── shl/
│   ├── engine/
│   │   ├── core.py
│   │   ├── localizer.py
│   │   ├── template_localizer.py
│   │   ├── ai_translation.py
│   │   └── __init__.py
│   ├── data/
│   │   └── unified_languages.json  # GLFM database
│   ├── language_validator.py
│   ├── logging_config.py
│   └── __init__.py
│
├── tests/
│   ├── test_localizer.py
│   ├── test_template_localizer.py
│   ├── test_core.py
│   ├── test_ai_translation.py
│   ├── test_language_validator.py
│   └── conftest.py
│
├── pyproject.toml
└── README.md

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API Reference (v0.1.7)

LocalizationEngine

engine = LocalizationEngine(
    lang_code=None,        # None = auto-detect from config.conf or LANG env
    base_lang="en",
    ui_folder="locales",
    template_folder="prompts",
    config=None,           # Custom configuration dict
    glfm_path=None         # Path to GLFM unified_languages.json
)

Method	Description
engine.ui_text(key, default_value="")	Retrieve UI text with self-healing
engine.template(key, default="", **kwargs)	Retrieve prompt template with self-healing
engine.set_language(lang_code)	Switch language dynamically
engine.ensure_language(lang_code)	Ensure language files exist
engine.sync()	Synchronize all keys from base language
engine.get_stats()	Return engine statistics
engine.ensure_ui_key(key, default="")	Ensure UI key exists
engine.ensure_template_key(key, default="")	Ensure template key exists

AITranslator

from shl.engine.ai_translation import AITranslator

translator = AITranslator(
    provider="auto",                    # "auto", "mymemory", "libretranslate", "none"
    libretranslate_url=None,            # Override LibreTranslate server
    libretranslate_api_key=None,        # Override LibreTranslate API key
    mymemory_email=None                 # Override MyMemory email
)

text = translator.translate("Hello", target_lang="fi")
batch = translator.batch_translate({"a": "Hello", "b": "Goodbye"}, "fi")

Method	Description
translate_text(text, target_lang, source_lang)	Translate with full fallback chain
get_supported_languages(base_url)	Fetch languages from LibreTranslate instance

Configuration (config.conf)

[SETTINGS]
language = fi
ai_translation_enabled = true
fallback_to_base = true

If no language is provided programmatically, SHL reads the language from '''config.conf'''.

Translation Services

| Service | Role | Limits | |--------|-------------| | MyMemory | Primary | 1,000 chars/day (30,000 with email)| | LibreTranslate | Fallback | Public instance, rate limited |

Both work without API keys. API key support available via .env file.

🛠 Roadmap

[v0.1.x]

• Core self-healing logic and modular engine.

[v0.1.4]

• Basic automatic translation engine (e.g., English -> Finnish).

[v0.1.5] - 2026-01-19 - RELEASED

• Fixed incorrect constructor argument usage in core engine. Internal fix, no API change.
• Initial PyPI release.

[v0.1.6] - 2026-07-26 - Test PyPI RELEASE

• Core self-healing logic and modular engine
• AI translations (MyMemory + LibreTranslate fallback)
• Translation cache for API call optimization
• Corrupted JSON file backup (.bak)
• Unified logging with configurable levels
• Dynamic language switching (set_language())
• Key validation and normalization
• Unit tests (pytest)
• None vs "" consistency
• Test PyPI release

[v0.1.7] - Current Test PyPI Release

• GLFM integration (7,900+ languages)
• Region subtag support (zh-TW, pt-BR)
• Dynamic language detection with 24h cache
• Environment variable support (.env)
• Improved error handling (403, 429)
• Language code normalization
• MyMemory email support
• 106 unit tests

[v0.2.0]

• AI‑powered translation (Gemini / Groq / OpenAI)
• CLI tool (selfheal sync, selfheal translate)
• Automatic detection of missing keys across all languages
• Async support

[v0.3.0]

• Web‑based Localization Studio
• Visual diffing of translations
• Export/import language packs

[v1.0.0]

• Full ecosystem integrations (Flask, FastAPI, Django, Flet)
• Community templates

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Contributing

Contributions are welcome.
This project aims to become a new standard for open‑source localization — simple, automatic, and self‑maintaining.

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License

MIT License — free for personal and commercial use.

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Vision

Localization should never be a burden.

With SHL, any project can become multilingual — automatically, reliably, and without manual maintenance.

No more missing translations.
No more incomplete language packs.
Localization that heals itself.

#localization • #i18n • #l10n • #self-healing • #translation • #multilingual #json • #python • #developer-tools • #automation • #templates • #cli #ai-assisted • #language-files • #internationalization • #localization-engine