diff --git a/server/index.js b/server/index.js
index fa6f142f..7dd1e314 100755
--- a/server/index.js
+++ b/server/index.js
@@ -19,7 +19,6 @@ import { getConnectableHost } from '../shared/networkHosts.js';
 
 import { findAppRoot, getModuleDir } from './utils/runtime-paths.js';
 import {
-    renameProjectById,
     deleteSessionById,
     deleteProjectById,
     getProjectPathById,
@@ -302,17 +301,6 @@ app.post('/api/system/update', authenticateToken, async (req, res) => {
     }
 });
 
-// Rename project endpoint; stores the custom name on the DB row for `projectId`.
-app.put('/api/projects/:projectId/rename', authenticateToken, async (req, res) => {
-    try {
-        const { displayName } = req.body;
-        await renameProjectById(req.params.projectId, displayName);
-        res.json({ success: true });
-    } catch (error) {
-        res.status(500).json({ error: error.message });
-    }
-});
-
 // Delete session endpoint; resolves `projectId` to path before touching disk.
 app.delete('/api/projects/:projectId/sessions/:sessionId', authenticateToken, async (req, res) => {
     try {
diff --git a/server/modules/projects/projects.routes.ts b/server/modules/projects/projects.routes.ts
index 6ee65104..b593f60c 100644
--- a/server/modules/projects/projects.routes.ts
+++ b/server/modules/projects/projects.routes.ts
@@ -1,6 +1,6 @@
 import express from 'express';
 
-import { createProject } from '@/modules/projects/services/project-management.service.js';
+import { createProject, updateProjectDisplayName } from '@/modules/projects/services/project-management.service.js';
 import { startCloneProject } from '@/modules/projects/services/project-clone.service.js';
 import { getProjectTaskMaster } from '@/modules/projects/services/projects-has-taskmaster.service.js';
 import { AppError, asyncHandler } from '@/shared/utils.js';
@@ -166,4 +166,15 @@ router.get(
   }),
 );
 
+router.put('/:projectId/rename', (req, res) => {
+  try {
+    const projectId = typeof req.params.projectId === 'string' ? req.params.projectId : '';
+    const { displayName } = req.body as { displayName?: unknown };
+    updateProjectDisplayName(projectId, displayName);
+    res.json({ success: true });
+  } catch (error) {
+    res.status(500).json({ error: error instanceof Error ? error.message : 'Failed to rename project' });
+  }
+});
+
 export default router;
diff --git a/server/modules/projects/services/project-management.service.ts b/server/modules/projects/services/project-management.service.ts
index e25e90b1..4362c487 100644
--- a/server/modules/projects/services/project-management.service.ts
+++ b/server/modules/projects/services/project-management.service.ts
@@ -140,3 +140,11 @@ export async function createProject(
     project: mapProjectRowToApiView(projectRow),
   };
 }
+
+/**
+ * Sets `projects.custom_project_name` for the given `projectId` (or clears it when empty).
+ */
+export function updateProjectDisplayName(projectId: string, newDisplayName: unknown): void {
+  const trimmed = typeof newDisplayName === 'string' ? newDisplayName.trim() : '';
+  projectsDb.updateCustomProjectNameById(projectId, trimmed.length > 0 ? trimmed : null);
+}
diff --git a/server/projects.js b/server/projects.js
index eae9c375..332696b6 100755
--- a/server/projects.js
+++ b/server/projects.js
@@ -666,57 +666,6 @@ async function getSessionMessages(projectName, sessionId, limit = null, offset =
   }
 }
 
-// Rename a project's display name
-async function renameProject(projectName, newDisplayName) {
-  const config = await loadProjectConfig();
-
-  if (!newDisplayName || newDisplayName.trim() === '') {
-    // Remove custom name if empty, will fall back to auto-generated
-    if (config[projectName]) {
-      delete config[projectName].displayName;
-    }
-  } else {
-    // Set custom display name, preserving other properties (manuallyAdded, originalPath)
-    config[projectName] = {
-      ...config[projectName],
-      displayName: newDisplayName.trim()
-    };
-  }
-
-  await saveProjectConfig(config);
-  return true;
-}
-
-/**
- * ID-based wrapper around `renameProject`.
- *
- * Writes the new display name to the `projects.custom_project_name` column
- * (the source of truth for the DB-driven getProjectsWithSessions() response) and also
- * keeps the legacy project-config.json in sync for backwards compatibility
- * with any code that still reads it.
- */
-async function renameProjectById(projectId, newDisplayName) {
-  const projectPath = await getProjectPathById(projectId);
-  if (!projectPath) {
-    throw new Error(`Unknown projectId: ${projectId}`);
-  }
-
-  const trimmed = typeof newDisplayName === 'string' ? newDisplayName.trim() : '';
-  // Persist on the DB row so getProjectsWithSessions() immediately reflects the change.
-  projectsDb.updateCustomProjectNameById(projectId, trimmed.length > 0 ? trimmed : null);
-
-  // Keep the legacy file-based project config in lockstep so historic readers
-  // that still consult project-config.json don't diverge.
-  const claudeFolderName = claudeFolderNameFromPath(projectPath);
-  try {
-    await renameProject(claudeFolderName, trimmed);
-  } catch (error) {
-    console.warn(`[projects] Legacy renameProject sync failed for ${projectId}:`, error.message);
-  }
-
-  return true;
-}
-
 /**
  * ID-based wrapper around `deleteSession`.
  *
@@ -2030,11 +1979,10 @@ async function getGeminiCliSessionMessages(sessionId) {
 }
 
 // Only functions with consumers outside this module are exported. Folder-name
-// based helpers (`getSessions`, `renameProject`, `deleteSession`, etc.) are
-// kept as internal implementation details of the id-based wrappers below.
+// based helpers (`getSessions`, `deleteSession`, etc.) are kept as internal
+// implementation details of the id-based wrappers below.
 export {
   getSessionMessages,
-  renameProjectById,
   deleteSessionById,
   deleteProjectById,
   addProjectManually,