Handle pure insertions and deletions with diffs

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

@@ -33,6 +33,10 @@ function levenshteinDistance(a: string, b: string): number {
 }
 
 function getSimilarity(original: string, search: string): number {
+    if (original === '' || search === '') {
+        return 1;
+    }
+
     // Normalize strings by removing extra whitespace but preserve case
     const normalizeStr = (str: string) => str.replace(/\s+/g, ' ').trim();
     
@@ -71,8 +75,8 @@ If you're not confident in the exact content to search for, use the read_file to
 Parameters:
 - path: (required) The path of the file to modify (relative to the current working directory ${cwd})
 - diff: (required) The search/replace block defining the changes.
-- start_line: (required) The line number where the search block starts.
-- end_line: (required) The line number where the search block ends.
+- start_line: (required) The line number where the search block starts (inclusive).
+- end_line: (required) The line number where the search block ends (inclusive).
 
 Diff format:
 \`\`\`
@@ -94,35 +98,84 @@ Original file:
 5 |     return total
 \`\`\`
 
-Search/Replace content:
+1. Search/replace a specific chunk of code:
 \`\`\`
+<apply_diff>
+<path>File path here</path>
+<diff>
 <<<<<<< SEARCH
-def calculate_total(items):
     total = 0
     for item in items:
         total += item
     return total
 =======
-def calculate_total(items):
     """Calculate total with 10% markup"""
     return sum(item * 1.1 for item in items)
 >>>>>>> REPLACE
+</diff>
+<start_line>2</start_line>
+<end_line>5</end_line>
+</apply_diff>
 \`\`\`
 
-Usage:
+Result:
+\`\`\`
+1 | def calculate_total(items):
+2 |     """Calculate total with 10% markup"""
+3 |     return sum(item * 1.1 for item in items)
+\`\`\`
+
+2. Insert code at a specific line (start_line and end_line must be the same, and the content gets inserted before whatever is currently at that line):
+\`\`\`
 <apply_diff>
 <path>File path here</path>
 <diff>
-Your search/replace content here
+<<<<<<< SEARCH
+=======
+    """TODO: Write a test for this"""
+>>>>>>> REPLACE
 </diff>
-<start_line>1</start_line>
+<start_line>2</start_line>
+<end_line>2</end_line>
+</apply_diff>
+\`\`\`
+
+Result:
+\`\`\`
+1 | def calculate_total(items):
+2 |     """TODO: Write a test for this"""
+3 |     """Calculate total with 10% markup"""
+4 |     return sum(item * 1.1 for item in items)
+\`\`\`
+
+3. Delete code at a specific line range:
+\`\`\`
+<apply_diff>
+<path>File path here</path>
+<diff>
+<<<<<<< SEARCH
+    total = 0
+    for item in items:
+        total += item
+    return total
+=======
+>>>>>>> REPLACE
+</diff>
+<start_line>2</start_line>
 <end_line>5</end_line>
-</apply_diff>`
+</apply_diff>
+\`\`\`
+
+Result:
+\`\`\`
+1 | def calculate_total(items):
+\`\`\`
+`
     }
 
     applyDiff(originalContent: string, diffContent: string, startLine?: number, endLine?: number): DiffResult {
         // Extract the search and replace blocks
-        const match = diffContent.match(/<<<<<<< SEARCH\n([\s\S]*?)\n=======\n([\s\S]*?)\n>>>>>>> REPLACE/);
+        const match = diffContent.match(/<<<<<<< SEARCH\n([\s\S]*?)\n?=======\n([\s\S]*?)\n?>>>>>>> REPLACE/);
         if (!match) {
             const debugInfo = this.debugEnabled ? `\n\nDebug Info:\n- Expected Format: <<<<<<< SEARCH\\n[search content]\\n=======\\n[replace content]\\n>>>>>>> REPLACE\n- Tip: Make sure to include both SEARCH and REPLACE sections with correct markers` : '';
 
@@ -133,7 +186,7 @@ Your search/replace content here
         }
 
         let [_, searchContent, replaceContent] = match;
-        
+
         // Detect line ending from original content
         const lineEnding = originalContent.includes('\r\n') ? '\r\n' : '\n';
 
@@ -145,7 +198,7 @@ Your search/replace content here
 
         if (hasLineNumbers(searchContent) && hasLineNumbers(replaceContent)) {
             const stripLineNumbers = (content: string) => {
-                return content.replace(/^\d+\s+\|(?!\|)/gm, '') 
+                return content.replace(/^\d+\s+\|(?!\|)/gm, '');
             };
 
             searchContent = stripLineNumbers(searchContent);
@@ -153,8 +206,8 @@ Your search/replace content here
         }
         
         // Split content into lines, handling both \n and \r\n
-        const searchLines = searchContent.split(/\r?\n/);
-        const replaceLines = replaceContent.split(/\r?\n/);
+        const searchLines = searchContent === '' ? [] : searchContent.split(/\r?\n/);
+        const replaceLines = replaceContent === '' ? [] : replaceContent.split(/\r?\n/);
         const originalLines = originalContent.split(/\r?\n/);
         
         // First try exact line range if provided
@@ -167,9 +220,15 @@ Your search/replace content here
             const exactStartIndex = startLine - 1;
             const exactEndIndex = endLine - 1;
 
-            if (exactStartIndex < 0 || exactEndIndex >= originalLines.length || exactStartIndex > exactEndIndex) {
+            if (exactStartIndex < 0 || exactEndIndex > originalLines.length || exactStartIndex > exactEndIndex) {
                 const debugInfo = this.debugEnabled ? `\n\nDebug Info:\n- Requested Range: lines ${startLine}-${endLine}\n- File Bounds: lines 1-${originalLines.length}` : '';
     
+                // Log detailed debug information
+                console.log('Invalid Line Range Debug:', {
+                    requestedRange: { start: startLine, end: endLine },
+                    fileBounds: { start: 1, end: originalLines.length }
+                });
+
                 return {
                     success: false,
                     error: `Line range ${startLine}-${endLine} is invalid (file has ${originalLines.length} lines)${debugInfo}`,
@@ -263,7 +322,7 @@ Your search/replace content here
         // Apply the replacement while preserving exact indentation
         const indentedReplaceLines = replaceLines.map((line, i) => {
             // Get the matched line's exact indentation
-            const matchedIndent = originalIndents[0];
+            const matchedIndent = originalIndents[0] || '';
             
             // Get the current line's indentation relative to the search content
             const currentIndentMatch = line.match(/^[\t ]*/);