Make fuzzy diff matching configurable (and default to off)

src/core/diff/DiffStrategy.ts

@@ -6,10 +6,10 @@ import { SearchReplaceDiffStrategy } from './strategies/search-replace'
  * @param model The name of the model being used (e.g., 'gpt-4', 'claude-3-opus')
  * @returns The appropriate diff strategy for the model
  */
-export function getDiffStrategy(model: string): DiffStrategy {
-    // For now, return SearchReplaceDiffStrategy for all models (with a fuzzy threshold of 0.9)
+export function getDiffStrategy(model: string, fuzzyMatchThreshold?: number): DiffStrategy {
+    // For now, return SearchReplaceDiffStrategy for all models
     // This architecture allows for future optimizations based on model capabilities
-    return new SearchReplaceDiffStrategy(0.9)
+    return new SearchReplaceDiffStrategy(fuzzyMatchThreshold ?? 1.0)
 }
 
 export type { DiffStrategy }

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

@@ -58,7 +58,9 @@ export class SearchReplaceDiffStrategy implements DiffStrategy {
     private bufferLines: number;
 
     constructor(fuzzyThreshold?: number, bufferLines?: number) {
-        // Default to exact matching (1.0) unless fuzzy threshold specified
+        // Use provided threshold or default to exact matching (1.0)
+        // Note: fuzzyThreshold is inverted in UI (0% = 1.0, 10% = 0.9)
+        // so we use it directly here
         this.fuzzyThreshold = fuzzyThreshold ?? 1.0;
         this.bufferLines = bufferLines ?? BUFFER_LINES;
     }