feat: Add offline translation cache and real-time language detection

[a-malik-gh]

Summary

This PR implements two key translation features as part of the Stellar Wave Program:

Issue #67: Add Offline Translation Cache for Recent Phrases

• Feature: Offline translation caching system
• Location: mobile/app/src/storage/TranslationCache.ts
• Capabilities:
  • Cache recently translated phrases locally using AsyncStorage
  • Support configurable TTL (Time-to-Live) with default 7-day expiry
  • Automatic cleanup of expired entries
  • Duplicate prevention with unique ID generation
  • Maximum cache size management (default 100 entries)
  • Methods to retrieve single translations, all translations, or by language pair

Issue #66: Implement Real-Time Language Detection in Chat Input

• Feature: Real-time language detection with debouncing

• Components:

  1. mobile/app/src/features/translate/languageDetection.ts - Language detection service
  2. mobile/app/src/hooks/useLanguageDetection.ts - React hook for language detection
  3. mobile/app/src/components/LanguageInput.tsx - UI component with built-in detection

• Capabilities:

  • Automatic language detection while typing
  • Debounced API calls (300ms) to prevent excessive requests
  • Fallback detection using Unicode pattern matching when API is unavailable
  • Manual language override with dropdown selection
  • Display of detection confidence percentage
  • Alternative language suggestions
  • Proper React component with typed props

Technical Details

TranslationCache

• Uses AsyncStorage for non-sensitive persistent storage
• Implements LRU-like behavior with timestamp tracking
• Automatic expiration cleanup
• Configurable via CacheConfig interface

LanguageDetection

• Supports 12+ languages (en, es, fr, de, it, pt, ru, ar, zh, ja, ko, hi)
• 0.6 confidence threshold for auto-detection
• Pattern-based fallback for offline scenarios
• Debounce prevents excessive API calls

LanguageInput Component

• Forward ref support for direct input access
• Integrated detection badge showing language and confidence
• Manual override dropdown
• Alternative suggestions when available
• Styled for React Native with TouchableOpacity controls
• Configurable via props (placeholder, multiline, etc.)

Testing Notes

• All features include proper error handling
• Console logging for debugging
• Type-safe implementations with full TypeScript support
• Compatible with React Native Expo setup

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Closes #67 Closes #66

Executive Summary

Linked Issues & References

• Issue: Resolves #
• Related PRs:

Type of Change

Category

• New Feature (Non-breaking change adding functionality)
• Bug Fix (Non-breaking change fixing an issue)
• Performance Optimization (Code change to improve efficiency)
• Refactoring (Code structure change without external API modification)
• Security Patch (Fixing a vulnerability or security concern)
• Documentation (Updates to README, Wiki, or inline docs)
• Infrastructure (CI/CD, build scripts, Docker)

Domain

• Smart Contracts (Rust/Soroban)
• SDK/Backend (NestJS/TypeScript)
• Frontend/UI

Technical Implementation Details

Breaking Changes

• No - Backward compatibility is maintained.
• Yes - This change requires consumers of the SDK/Contract to update their code.

Verification & Testing Strategy

Automated Tests

• Unit Tests: Added/Updated new unit tests.
• Integration Tests: Verified interaction between modules.
• Linting: Code follows the project's style guide.

Manual Verification

1. Environment:

• Target Environment:

2. Reproduction Steps:

3. Proof of Execution:

Quality Assurance Checklist

• I have performed a self-review of my own code.
• I have commented on my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect these changes.
• My changes do not generate new warnings or errors.
• I have verified that new dependencies are necessary and secure.
• (If Smart Contract) I have verified gas usage and storage footprints are optimized.

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By submitting this Pull Request, I acknowledge that I have adhered to the Bridgelet contribution guidelines.

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