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Dynamic Prompt Generation

System prompts are generated dynamically based on detected language, conversation context, and configuration settings.

Language Selection Flow​

Implementation​

Location: app/api/chat/system-prompt.ts:246-292

export function generateDynamicSystemPrompt(
  language?: 'et' | 'en' | 'mixed',
  context?: { recipient?: string; occasion?: string; productType?: string }
): string {
  // STEP 1: Select base prompt by language
  // Rules:
  // 1. Estonian query ('et') → Estonian prompt
  // 2. English query ('en') → English prompt
  // 3. Mixed query ('mixed') → Estonian prompt (default)
  // 4. Undefined → Estonian prompt (primary market)
  
  let basePrompt = (!language || language === 'mixed' || language === 'et')
    ? buildEstonianSystemPrompt()
    : buildEnglishSystemPrompt();
  
  console.log('📋 SYSTEM PROMPT: Language-based prompt selection', {
    detectedLanguage: language || 'undefined (default to et)',
    promptLanguage: (!language || language === 'mixed' || language === 'et') 
      ? 'Estonian' 
      : 'English',
    rule: getRuleApplied(language)
  });
  
  // STEP 2: Add context reminders for multi-turn coherence
  if (context) {
    const isEstonian = (!language || language === 'mixed' || language === 'et');
    let contextReminders = '';
    
    if (context.recipient) {
      contextReminders += isEstonian
        ? `\n\nKONTEKSTI MEELDETULETUS: Tooted on sobivad "${context.recipient}" jaoks - mainige seda vastuses!`
        : `\n\nCONTEXT REMINDER: Products are suitable for "${context.recipient}" - mention this in your response!`;
    }
    
    if (context.occasion && !context.recipient) {
      contextReminders += isEstonian
        ? `\n\nKONTEKSTI MEELDETULETUS: Need sobivad puhuseks "${context.occasion}" - mainige seda!`
        : `\n\nCONTEXT REMINDER: These are for "${context.occasion}" - mention this occasion!`;
    }
    
    if (contextReminders) {
      basePrompt += contextReminders;
    }
  }
  
  return basePrompt;
}

Context Adaptation​

Recipient Context​

When user specifies recipient:

context = { recipient: "ema" }

// Adds to prompt:
"KONTEKSTI MEELDETULETUS: Tooted on sobivad "ema" jaoks - 
mainige seda vastuses!"

AI Output:

"Siin on suurepärased kingitused sinu emale..."

Occasion Context​

When user specifies occasion:

context = { occasion: "sünnipäev" }

// Adds to prompt:
"KONTEKSTI MEELDETULETUS: Need sobivad puhuseks "sünnipäev" - 
mainige seda!"

AI Output:

"Need raamatud teevad unustamatu sünnipäevakingituse..."

Combined Context​

Both recipient and occasion:

context = { 
  recipient: "sõber",
  occasion: "sünnipäev"
}

// Only recipient reminder added
// (occasion implied in recipient context)

Multi-Turn Coherence Strategy​

Problem: AI forgets context between turns

Solution: Context reminders in system prompt

Example Flow​

Turn 1:
User: "kingitus 10-aastasele tüdrukule"
Context: { recipient: "10-aastane tüdruk" }
AI: [Products with context]

Turn 2:
User: "näita rohkem"
Context: { recipient: "10-aastane tüdruk" } ← PRESERVED
Prompt: + "Products are suitable for 10-aastane tüdruk"
AI: "Veel suurepäraseid valikuid 10-aastasele tüdrukule!"
       ↑ Mentions recipient naturally ↑

Logging & Debugging​

console.log('📋 SYSTEM PROMPT: Language-based prompt selection', {
  detectedLanguage: 'et',
  promptLanguage: 'Estonian',
  rule: 'Rule 1: Estonian → Estonian'
});

console.log('📋 CONTEXT REMINDERS ADDED', {
  recipient: 'ema',
  occasion: null,
  reminderCount: 1
});

Performance​

Prompt generation time:

Language detection: ~5ms
Base prompt selection: <1ms
Context reminders: ~2ms
Enrichment section: ~1ms
────────────────────────
Total: ~9ms ✓

Token impact:

Base Estonian prompt: ~350 tokens
+ Context reminder: ~25 tokens
+ Enrichment section: ~50 tokens
─────────────────────────────
Total: ~425 tokens

Edge Cases​

Case 1: Language Mismatch​

Scenario: User writes in English, but language detected as 'et'

Resolution:

// GPT-5.1 is smart enough to respond in appropriate language
// even if prompt is in different language

// Fallback: Response validation catches language mismatch
if (userLanguage !== responseLanguage) {
  console.warn('Language mismatch detected');
  // Log for analysis
}

Case 2: Mixed Language Query​

Scenario: "Tere, I want books for sünnipäev"

Resolution:

language = 'mixed'
→ Estonian prompt (Rule 3)
→ GPT-5.1 responds in Estonian (primary market)

Case 3: Context Changes Mid-Conversation​

Scenario:

Turn 1: "kingitus emale" (recipient: ema)
Turn 2: "kingitus isale" (recipient: isa)

Resolution:

// Context updated for Turn 2
context = { recipient: "isa" }  // New context
// Prompt includes new recipient reminder
// AI correctly switches context

Testing​

describe('Dynamic Prompt Generation', () => {
  it('selects Estonian for et language', () => {
    const prompt = generateDynamicSystemPrompt('et');
    expect(prompt).toContain('Olen RahvaRaamatu AI ostuabi');
  });
  
  it('selects English for en language', () => {
    const prompt = generateDynamicSystemPrompt('en');
    expect(prompt).toContain('I am RahvaRaamat AI');
  });
  
  it('defaults to Estonian for mixed', () => {
    const prompt = generateDynamicSystemPrompt('mixed');
    expect(prompt).toContain('eesti keeles');
  });
  
  it('adds context reminders', () => {
    const prompt = generateDynamicSystemPrompt('et', {
      recipient: 'ema'
    });
    
    expect(prompt).toContain('KONTEKSTI MEELDETULETUS');
    expect(prompt).toContain('"ema"');
  });
});