From 246d8491639cb39cff9233ac1d9cd647108dcb4d Mon Sep 17 00:00:00 2001
From: Joshua Ryder <ryderjj89@outlook.com>
Date: Mon, 10 Nov 2025 20:05:29 -0500
Subject: [PATCH] Enhance: Add exact match boosting to search relevance scoring
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FTS5 with Porter stemming treats 'kindness' and 'kind' as the same root word,
which caused stemmed matches to rank equally with exact matches. This adds a
secondary relevance boost on top of BM25 to prioritize exact matches.

Relevance scoring now:
- BM25 base score (from FTS5)
- +100 for exact phrase match in verse text
- +50 per exact word match (e.g., 'kindness' exactly)
- +10 per partial/stemmed match (e.g., 'kind' via stemming)

Example: Searching for 'kindness'
- Verses with 'kindness': BM25 + 150 (phrase + word)
- Verses with 'kind': BM25 + 10 (partial match)

This ensures exact matches appear first while still benefiting from Porter
stemming to find all word variations.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 backend/src/searchDatabase.js | 63 +++++++++++++++++++++++++++++------
 1 file changed, 52 insertions(+), 11 deletions(-)

diff --git a/backend/src/searchDatabase.js b/backend/src/searchDatabase.js
index e2bd63f1..43512586 100644
--- a/backend/src/searchDatabase.js
+++ b/backend/src/searchDatabase.js
@@ -199,17 +199,25 @@ class SearchDatabase {
           return reject(err);
         }
 
-        // Format results
-        const results = rows.map(row => ({
-          book: row.book,
-          chapter: row.chapter,
-          verse: row.verse_number,
-          text: row.verse_text,
-          version: row.version,
-          highlight: row.highlighted_text,
-          relevance: -row.rank, // BM25 returns negative scores, negate for consistency
-          context: [] // Will be populated if requested
-        }));
+        // Format results with enhanced relevance scoring
+        const results = rows.map(row => {
+          const bm25Score = -row.rank; // BM25 returns negative scores
+          const exactMatchBoost = this.calculateExactMatchBoost(row.verse_text, query);
+
+          return {
+            book: row.book,
+            chapter: row.chapter,
+            verse: row.verse_number,
+            text: row.verse_text,
+            version: row.version,
+            highlight: row.highlighted_text,
+            relevance: bm25Score + exactMatchBoost,
+            context: [] // Will be populated if requested
+          };
+        });
+
+        // Re-sort by enhanced relevance (BM25 + exact match boost)
+        results.sort((a, b) => b.relevance - a.relevance);
 
         // Add context if requested
         if (includeContext && results.length > 0) {
@@ -269,6 +277,39 @@ class SearchDatabase {
     return words.join(' AND ');
   }
 
+  // Calculate exact match boost for better relevance ranking
+  calculateExactMatchBoost(verseText, query) {
+    const lowerText = verseText.toLowerCase();
+    const lowerQuery = query.toLowerCase().replace(/['"]/g, ''); // Remove quotes
+    let boost = 0;
+
+    // Exact phrase match (highest boost) - e.g., "faith hope love"
+    if (lowerText.includes(lowerQuery)) {
+      boost += 100;
+    }
+
+    // Exact word match boost - prioritize exact words over stemmed variants
+    const queryWords = lowerQuery.split(/\s+/).filter(w => w.length > 0);
+    const textWords = lowerText.split(/\W+/).filter(w => w.length > 0);
+
+    for (const queryWord of queryWords) {
+      // Exact word match (e.g., "kindness" matches "kindness", not just "kind")
+      if (textWords.includes(queryWord)) {
+        boost += 50;
+      } else {
+        // Partial match (stemmed or substring) - lower boost
+        for (const textWord of textWords) {
+          if (textWord.includes(queryWord) || queryWord.includes(textWord)) {
+            boost += 10;
+            break; // Only count once per query word
+          }
+        }
+      }
+    }
+
+    return boost;
+  }
+
   // Get context verses around a target verse
   async getContext(book, chapter, verseNumber, version, contextSize = 2) {
     const start = Math.max(1, verseNumber - contextSize);