Prioritize exact line matches in search/replace

src/core/diff/strategies/__tests__/search-replace.test.ts

@@ -610,6 +610,95 @@ function two() {
 
 function three() {
     return 3;
+}`)
+        })
+
+        it('should prioritize exact line match over expanded search', () => {
+            const originalContent = `
+function one() {
+    return 1;
+}
+
+function process() {
+    return "old";
+}
+
+function process() {
+    return "old";
+}
+
+function two() {
+    return 2;
+}`
+            const diffContent = `test.ts
+<<<<<<< SEARCH
+function process() {
+    return "old";
+}
+=======
+function process() {
+    return "new";
+}
+>>>>>>> REPLACE`
+
+            // Should match the second instance exactly at lines 10-12
+            // even though the first instance at 6-8 is within the expanded search range
+            const result = strategy.applyDiff(originalContent, diffContent, 10, 12)
+            expect(result).toBe(`
+function one() {
+    return 1;
+}
+
+function process() {
+    return "old";
+}
+
+function process() {
+    return "new";
+}
+
+function two() {
+    return 2;
+}`)
+            })
+
+        it('should fall back to expanded search only if exact match fails', () => {
+            const originalContent = `
+function one() {
+    return 1;
+}
+
+function process() {
+    return "target";
+}
+
+function two() {
+    return 2;
+}`.trim()
+    const diffContent = `test.ts
+<<<<<<< SEARCH
+function process() {
+    return "target";
+}
+=======
+function process() {
+    return "updated";
+}
+>>>>>>> REPLACE`
+
+            // Specify wrong line numbers (3-5), but content exists at 6-8
+            // Should still find and replace it since it's within the expanded range
+            const result = strategy.applyDiff(originalContent, diffContent, 3, 5)
+            expect(result).toBe(`function one() {
+    return 1;
+}
+
+function process() {
+    return "updated";
+}
+
+function two() {
+    return 2;
 }`)
         })
     })

src/core/diff/strategies/search-replace.ts

@@ -132,7 +132,28 @@ Your search/replace content here
         const replaceLines = replaceContent.split(/\r?\n/);
         const originalLines = originalContent.split(/\r?\n/);
         
-        // Determine search range based on provided line numbers
+        // First try exact line range if provided
+        let matchIndex = -1;
+        let bestMatchScore = 0;
+        
+        if (startLine !== undefined && endLine !== undefined) {
+            // Convert to 0-based index
+            const exactStartIndex = startLine - 1;
+            const exactEndIndex = endLine - 1;
+
+            // Check exact range first
+            const originalChunk = originalLines.slice(exactStartIndex, exactEndIndex + 1).join('\n');
+            const searchChunk = searchLines.join('\n');
+            
+            const similarity = getSimilarity(originalChunk, searchChunk);
+            if (similarity >= this.fuzzyThreshold) {
+                matchIndex = exactStartIndex;
+                bestMatchScore = similarity;
+            }
+        }
+
+        // If no match found in exact range, try expanded range
+        if (matchIndex === -1) {
             let searchStartIndex = 0;
             let searchEndIndex = originalLines.length;
 
@@ -146,10 +167,7 @@ Your search/replace content here
                 }
             }
 
-        // Find the search content in the original using fuzzy matching
-        let matchIndex = -1;
-        let bestMatchScore = 0;
-        
+            // Find the search content in the expanded range using fuzzy matching
             for (let i = searchStartIndex; i <= searchEndIndex - searchLines.length; i++) {
                 // Join the lines and calculate overall similarity
                 const originalChunk = originalLines.slice(i, i + searchLines.length).join('\n');
@@ -161,6 +179,7 @@ Your search/replace content here
                     matchIndex = i;
                 }
             }
+        }
 
         // Require similarity to meet threshold
         if (matchIndex === -1 || bestMatchScore < this.fuzzyThreshold) {