feat(coding-agent): expose edit tool unified patch

closes #4821

packages/coding-agent/src/core/tools/edit-diff.ts

@@ -259,8 +259,16 @@ export function applyEditsToNormalizedContent(
 	return { baseContent, newContent };
 }
 
+/** Generate a standard unified patch. */
+export function generateUnifiedPatch(path: string, oldContent: string, newContent: string, contextLines = 4): string {
+	return Diff.createTwoFilesPatch(path, path, oldContent, newContent, undefined, undefined, {
+		context: contextLines,
+		headerOptions: Diff.FILE_HEADERS_ONLY,
+	});
+}
+
 /**
- * Generate a unified diff string with line numbers and context.
+ * Generate a display-oriented diff string with line numbers and context.
  * Returns both the diff string and the first changed line number (in the new file).
  */
 export function generateDiffString(

packages/coding-agent/src/core/tools/edit.ts

@@ -13,6 +13,7 @@ import {
 	type EditDiffError,
 	type EditDiffResult,
 	generateDiffString,
+	generateUnifiedPatch,
 	normalizeToLF,
 	restoreLineEndings,
 	stripBom,
@@ -57,8 +58,10 @@ type LegacyEditToolInput = EditToolInput & {
 };
 
 export interface EditToolDetails {
-	/** Unified diff of the changes made */
+	/** Display-oriented diff of the changes made */
 	diff: string;
+	/** Standard unified patch of the changes made */
+	patch: string;
 	/** Line number of the first change in the new file (for editor navigation) */
 	firstChangedLine?: number;
 }
@@ -394,6 +397,7 @@ export function createEditToolDefinition(
 								}
 
 								const diffResult = generateDiffString(baseContent, newContent);
+								const patch = generateUnifiedPatch(path, baseContent, newContent);
 								resolve({
 									content: [
 										{
@@ -401,7 +405,7 @@ export function createEditToolDefinition(
 											text: `Successfully replaced ${edits.length} block(s) in ${path}.`,
 										},
 									],
-									details: { diff: diffResult.diff, firstChangedLine: diffResult.firstChangedLine },
+									details: { diff: diffResult.diff, patch, firstChangedLine: diffResult.firstChangedLine },
 								});
 							} catch (error: unknown) {
 								// Clean up abort handler.