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Estonian Compound Words Problem

The compound word detection failure was the most critical Estonian-specific bug encountered, causing 80% failure rate in certain gift scenarios.

The Problem​

Scenario​

User Query:

"Otsin luuleraamatut sõbrapäevakingiks"
Translation: "I'm looking for a poetry book for Valentine's gift"

Expected:

  • Detect "luuleraamatut" as explicit book request
  • Show poetry books
  • Type: Raamat

Actual (Before Fix):

  • LLM correctly detected: productType: "Raamat"
  • System added constraint: "Ei raamatuid" (No books)
  • Showed: Scented candles instead of books
  • Success rate: 20% (1/5 Valentine's scenarios)

Root Cause​

The Paradox​

The LLM correctly understood the Estonian compound word and set productType: "Raamat", but the system still excluded books.

Why?​

Three-part failure:

  1. Keyword-based filtering used hardcoded list
  2. Gift occasion override ran AFTER LLM extraction
  3. Signal loss in pipeline

Original Keyword List​

const BOOK_KEYWORDS = [
  'raamat',
  'raamatu',
  'raamatut',
  'raamatuid',
  'raamatud',
  'book',
  'books',
  'novel',
  'novels'
];
// Only 9 keywords!

Problem: Missing ALL compound words!

Solution: Expanded Keywords​

Location: extract-context.ts:30-73

const BOOK_KEYWORDS = [
  // Original keywords
  'raamat', 'raamatu', 'raamatut', 'raamatuid', 'raamatud',
  'book', 'books', 'novel', 'novels', 'romaan', 'romaani',
  
  //  Poetry books (3 cases each)
  'luuleraamat', 'luuleraamatu', 'luuleraamatut',
  
  //  Mystery books
  'krimiraamat', 'krimiraamatu', 'krimiraamatut',
  
  //  Sci-fi books
  'ulmeraamat', 'ulmeraamatu', 'ulmeraamatut',
  
  //  Fantasy books
  'fantaasiaraamat', 'fantaasiaraamatu', 'fantaasiaraamatut',
  
  //  Cookbooks
  'kokaraamat', 'kokaraamatu', 'kokaraamatut',
  
  //  Children's books
  'lasteraamat', 'lasteraamatu', 'lasteraamatut',
  
  //  Travel books
  'reisiraamat', 'reisiraamatu', 'reisiraamatut',
  
  //  Textbooks
  'õpperaamat', 'õpperaamatu', 'õpperaamatut'
] as const;

Result:

  • From 9 keywords to 39 keywords
  • Covers most common compound book types
  • Includes 3 main cases per compound

Enhanced Detection Function​

Location: extract-context.ts:375-414

const wantsBooksFromContext = (
  context: GiftContext, 
  userMessage?: string
): boolean => {
  // Check 1: LLM signals
  const productTypeIsBook = isBookSignal(context.productType);
  const categoryIsBook = isBookSignal(context.category);
  const productTypeHintsHaveBooks = context.productTypeHints?.some(isBookSignal);
  const categoryHintsHaveBooks = context.categoryHints?.some(isBookSignal);
  
  const wantsBooksFromSignals = 
    productTypeIsBook || 
    categoryIsBook || 
    productTypeHintsHaveBooks || 
    categoryHintsHaveBooks;
  
  // Check 2:  CRITICAL - Also check user message
  const normalizedMessage = normalizeMessage(userMessage);
  const messageHasBookKeyword = messageContainsKeyword(
    normalizedMessage, 
    BOOK_KEYWORDS
  );
  
  // Check 3: Negative phrase detection
  const negativeBookPhrase = findNegativeBookPhrase(normalizedMessage);
  
  // Final decision: Want books if no negative phrase AND (signals OR keywords)
  const wantsBooks = negativeBookPhrase 
    ? false 
    : (wantsBooksFromSignals || messageHasBookKeyword);
  
  return wantsBooks;
};

Key Improvement: Now checks BOTH:

  1. LLM-extracted signals (productType, category, hints)
  2. User message keywords (catches compounds LLM might miss)

Safety Override​

Location: extract-context.ts:492-497, 685-697

// Preserve initial book signals
const initialBookSignalsPresent = 
  isBookSignal(giftContext.productType) || 
  isBookSignal(giftContext.category) ||
  giftContext.productTypeHints?.some(isBookSignal) ||
  giftContext.categoryHints?.some(isBookSignal);

// ... later in processing ...

//  SAFETY OVERRIDE: Prevent false negatives
if (!wantsBooks && (initialBookSignalsPresent || messageHasBookKeyword)) {
  console.warn('[SAFETY] Overriding wantsBooks=false', {
    initialBookSignalsPresent,
    messageHasBookKeyword
  });
  wantsBooks = true; // Force to true
}

Why: Even if intermediate steps corrupt context, safety override catches the explicit signal.

Removed Problematic Override​

What was removed:

//  REMOVED: This overrode LLM decisions
if (ROMANTIC_OCCASIONS.includes(occasion)) {
  if (!explicitlyRequestedBooks) {
    queryRewrite.excludeProductTypes = ['Raamat'];
    queryRewrite.forceProductTypes = ['Kingitused'];
  }
}

Why it was wrong:

  • Assumed Valentine's = never books
  • But users DO want poetry books for Valentine's!
  • Overrode LLM's correct understanding

Test Results​

Query: "Otsin luuleraamatut sõbrapäevakingiks"​

Before Fix:

  • Constraints: "Ei raamatuid"
  • Showed: Scented candles
  • Success: 20%

After Fix:

  • Constraints: "affordable, romantic"
  • Showed: Romantic poetry books
  • Success: 80%

Improvement: 20% → 80% success rate

Remaining Limitations​

Rare Compounds Not in List​

// Not yet in list:
"biografiaraamat" (biography book)
"ajalooraamat" (history book)
"filosoofiaraamat" (philosophy book)

Mitigation: LLM signal checking still works as backup

Typos in Compounds​

"luleraamatut" (missing 'u')
"luuleraamaut" (wrong vowel)

Mitigation: LLM often corrects these internally

Case Endings Beyond Main Three​

// We only added nominative/genitive/partitive
// Missing rarer cases like:
"luuleraamatusse" (illative)
"luuleraamatus" (inessive)

Mitigation: These cases are rare in gift queries