diff --git a/app/src/utils/fileHelpers.test.ts b/app/src/utils/fileHelpers.test.ts
index f1fc0ab..3f9e9cc 100644
--- a/app/src/utils/fileHelpers.test.ts
+++ b/app/src/utils/fileHelpers.test.ts
@@ -83,7 +83,7 @@ describe('fileHelpers', () => {
       const filePath = 'folder/file.md';
 
       const expectedUrl =
-        'http://localhost:8080/api/v1/workspaces/my-workspace/files/folder%2Ffile.md';
+        'http://localhost:8080/api/v1/workspaces/my-workspace/files/content?file_path=folder%2Ffile.md';
       const actualUrl = getFileUrl(workspaceName, filePath);
 
       expect(actualUrl).toBe(expectedUrl);
@@ -94,7 +94,7 @@ describe('fileHelpers', () => {
       const filePath = 'file.md';
 
       const expectedUrl =
-        'http://localhost:8080/api/v1/workspaces/my%20workspace%20with%20spaces/files/file.md';
+        'http://localhost:8080/api/v1/workspaces/my%20workspace%20with%20spaces/files/content?file_path=file.md';
       const actualUrl = getFileUrl(workspaceName, filePath);
 
       expect(actualUrl).toBe(expectedUrl);
@@ -105,7 +105,7 @@ describe('fileHelpers', () => {
       const filePath = 'folder with spaces/file with spaces.md';
 
       const expectedUrl =
-        'http://localhost:8080/api/v1/workspaces/workspace/files/folder%20with%20spaces%2Ffile%20with%20spaces.md';
+        'http://localhost:8080/api/v1/workspaces/workspace/files/content?file_path=folder%20with%20spaces%2Ffile%20with%20spaces.md';
       const actualUrl = getFileUrl(workspaceName, filePath);
 
       expect(actualUrl).toBe(expectedUrl);
@@ -116,7 +116,7 @@ describe('fileHelpers', () => {
       const filePath = 'file?name=test.md';
 
       const expectedUrl =
-        'http://localhost:8080/api/v1/workspaces/test%26workspace/files/file%3Fname%3Dtest.md';
+        'http://localhost:8080/api/v1/workspaces/test%26workspace/files/content?file_path=file%3Fname%3Dtest.md';
       const actualUrl = getFileUrl(workspaceName, filePath);
 
       expect(actualUrl).toBe(expectedUrl);
@@ -127,7 +127,7 @@ describe('fileHelpers', () => {
       const filePath = 'ファイル.md';
 
       const expectedUrl =
-        'http://localhost:8080/api/v1/workspaces/%E3%83%97%E3%83%AD%E3%82%B8%E3%82%A7%E3%82%AF%E3%83%88/files/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB.md';
+        'http://localhost:8080/api/v1/workspaces/%E3%83%97%E3%83%AD%E3%82%B8%E3%82%A7%E3%82%AF%E3%83%88/files/content?file_path=%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB.md';
       const actualUrl = getFileUrl(workspaceName, filePath);
 
       expect(actualUrl).toBe(expectedUrl);
@@ -138,7 +138,7 @@ describe('fileHelpers', () => {
       const filePath = 'projects/2024/q1/report.md';
 
       const expectedUrl =
-        'http://localhost:8080/api/v1/workspaces/docs/files/projects%2F2024%2Fq1%2Freport.md';
+        'http://localhost:8080/api/v1/workspaces/docs/files/content?file_path=projects%2F2024%2Fq1%2Freport.md';
       const actualUrl = getFileUrl(workspaceName, filePath);
 
       expect(actualUrl).toBe(expectedUrl);
@@ -146,20 +146,20 @@ describe('fileHelpers', () => {
 
     it('handles edge cases with empty strings', () => {
       expect(getFileUrl('', '')).toBe(
-        'http://localhost:8080/api/v1/workspaces//files/'
+        'http://localhost:8080/api/v1/workspaces//files/content?file_path='
       );
       expect(getFileUrl('workspace', '')).toBe(
-        'http://localhost:8080/api/v1/workspaces/workspace/files/'
+        'http://localhost:8080/api/v1/workspaces/workspace/files/content?file_path='
       );
       expect(getFileUrl('', 'file.md')).toBe(
-        'http://localhost:8080/api/v1/workspaces//files/file.md'
+        'http://localhost:8080/api/v1/workspaces//files/content?file_path=file.md'
       );
     });
 
     it('uses the API base URL correctly', () => {
       const url = getFileUrl('test', 'file.md');
       expect(url).toBe(
-        'http://localhost:8080/api/v1/workspaces/test/files/file.md'
+        'http://localhost:8080/api/v1/workspaces/test/files/content?file_path=file.md'
       );
       expect(url).toContain(window.API_BASE_URL);
     });
diff --git a/app/src/utils/fileHelpers.ts b/app/src/utils/fileHelpers.ts
index bcc2dde..2f56f8d 100644
--- a/app/src/utils/fileHelpers.ts
+++ b/app/src/utils/fileHelpers.ts
@@ -13,5 +13,5 @@ export const isImageFile = (filePath: string): boolean => {
 export const getFileUrl = (workspaceName: string, filePath: string) => {
   return `${API_BASE_URL}/workspaces/${encodeURIComponent(
     workspaceName
-  )}/files/${encodeURIComponent(filePath)}`;
+  )}/files/content?file_path=${encodeURIComponent(filePath)}`;
 };
diff --git a/server/internal/handlers/file_handlers.go b/server/internal/handlers/file_handlers.go
index 5d79b21..33f37e1 100644
--- a/server/internal/handlers/file_handlers.go
+++ b/server/internal/handlers/file_handlers.go
@@ -2,9 +2,11 @@ package handlers
 
 import (
 	"io"
+	"mime"
 	"net/http"
 	"net/url"
 	"os"
+	"path/filepath"
 	"time"
 
 	"lemma/internal/context"
@@ -205,7 +207,13 @@ func (h *Handler) GetFileContent() http.HandlerFunc {
 			return
 		}
 
-		w.Header().Set("Content-Type", "text/plain")
+		// Detect MIME type based on file extension
+		contentType := mime.TypeByExtension(filepath.Ext(decodedPath))
+		if contentType == "" {
+			// Fallback to text/plain if MIME type cannot be determined
+			contentType = "text/plain"
+		}
+		w.Header().Set("Content-Type", contentType)
 		_, err = w.Write(content)
 		if err != nil {
 			log.Error("failed to write response",