diff --git a/src/aggregator/index.ts b/src/aggregator/index.ts
index 5deb268..cb64d1d 100644
--- a/src/aggregator/index.ts
+++ b/src/aggregator/index.ts
@@ -538,10 +538,11 @@ export class BacklogAggregator {
 				return Response.json({ error: "Task not found" }, { status: 404 });
 			}
 
-			// Find the task file path
-			const tasksDir = join(projectPath, "backlog", "tasks");
-			const taskFileName = `${taskId}.md`;
-			const taskFilePath = join(tasksDir, taskFileName);
+			// Use the stored file path from when the task was loaded
+			const taskFilePath = task.filePath;
+			if (!taskFilePath) {
+				return Response.json({ error: "Task file path not found" }, { status: 404 });
+			}
 
 			// Read the current task file
 			let content: string;
@@ -695,12 +696,15 @@ created_date: '${dateStr}'
 				return Response.json({ error: "Task not found" }, { status: 404 });
 			}
 
-			// Find the task file path
-			const tasksDir = join(projectPath, "backlog", "tasks");
+			// Use the stored file path from when the task was loaded
+			const taskFilePath = task.filePath;
+			if (!taskFilePath) {
+				return Response.json({ error: "Task file path not found" }, { status: 404 });
+			}
+
+			// Build archive path preserving the original filename
 			const archiveDir = join(projectPath, "backlog", "archive", "tasks");
-			const taskFileName = `${taskId}.md`;
-			const taskFilePath = join(tasksDir, taskFileName);
-			const archiveFilePath = join(archiveDir, taskFileName);
+			const archiveFilePath = join(archiveDir, basename(taskFilePath));
 
 			// Ensure archive directory exists
 			try {
@@ -754,10 +758,11 @@ created_date: '${dateStr}'
 				return Response.json({ error: "Task not found" }, { status: 404 });
 			}
 
-			// Find the task file path
-			const tasksDir = join(projectPath, "backlog", "tasks");
-			const taskFileName = `${taskId}.md`;
-			const taskFilePath = join(tasksDir, taskFileName);
+			// Use the stored file path from when the task was loaded
+			const taskFilePath = task.filePath;
+			if (!taskFilePath) {
+				return Response.json({ error: "Task file path not found" }, { status: 404 });
+			}
 
 			// Delete the file
 			try {