refactoring

backend/prisma/migrations/20260218000001_remove_unique_project_id_from_ongoing_timers/migration.sql

@@ -0,0 +1,4 @@
+-- Remove the erroneous UNIQUE constraint on ongoing_timers.project_id.
+-- Multiple users must be able to have concurrent timers on the same project.
+-- The one-timer-per-user constraint is correctly enforced by the UNIQUE on user_id.
+DROP INDEX IF EXISTS "ongoing_timers_project_id_key";

backend/prisma/schema.prisma

@@ -51,7 +51,7 @@ model Project {
   client   Client @relation(fields: [clientId], references: [id], onDelete: Cascade)
 
   timeEntries  TimeEntry[]
-  ongoingTimer OngoingTimer?
+  ongoingTimers OngoingTimer[]
 
   @@index([userId])
   @@index([clientId])
@@ -85,7 +85,7 @@ model OngoingTimer {
 
   userId    String  @map("user_id") @db.VarChar(255) @unique
   user      User    @relation(fields: [userId], references: [id], onDelete: Cascade)
-  projectId String? @unique @map("project_id")
+  projectId String? @map("project_id")
   project   Project? @relation(fields: [projectId], references: [id], onDelete: SetNull)
 
   @@index([userId])

backend/src/config/index.ts

@@ -40,8 +40,8 @@ export function validateConfig(): void {
   }
 
   if (config.session.secret.length < 32) {
-    console.warn(
+    throw new Error(
-      "Warning: SESSION_SECRET should be at least 32 characters for security",
+      "SESSION_SECRET must be at least 32 characters. Set a strong secret in your environment.",
     );
   }
 }

backend/src/routes/auth.routes.ts

@@ -6,7 +6,7 @@ import {
   handleCallback,
   getUserInfo,
 } from "../auth/oidc";
-import { syncUser } from "../middleware/auth";
+import { requireAuth, syncUser } from "../middleware/auth";
 import type { AuthenticatedRequest } from "../types";
 
 const router = Router();
@@ -84,12 +84,8 @@ router.post("/logout", (req: AuthenticatedRequest, res) => {
 });
 
 // GET /auth/me - Get current user
-router.get("/me", (req: AuthenticatedRequest, res) => {
+router.get("/me", requireAuth, (req: AuthenticatedRequest, res) => {
-  if (!req.session?.user) {
+  res.json(req.user);
-    res.status(401).json({ error: "Not authenticated" });
-    return;
-  }
-  res.json(req.session.user);
 });
 
 export default router;

backend/src/services/timeEntry.service.ts

@@ -1,9 +1,11 @@
 import { prisma } from "../prisma/client";
+import { Prisma } from "@prisma/client";
 import {
   NotFoundError,
   BadRequestError,
   ConflictError,
 } from "../errors/AppError";
+import { hasOverlappingEntries } from "../utils/timeUtils";
 import type {
   CreateTimeEntryInput,
   UpdateTimeEntryInput,
@@ -14,131 +16,93 @@ import type {
 export class TimeEntryService {
   async getStatistics(userId: string, filters: StatisticsFilters = {}) {
     const { startDate, endDate, projectId, clientId } = filters;
-    const where: {
-      userId: string;
-      startTime?: { gte?: Date; lte?: Date };
-      projectId?: string;
-      project?: { clientId?: string };
-    } = { userId };
 
-    if (startDate || endDate) {
+    // Build an array of safe Prisma SQL filter fragments to append as AND clauses.
-      where.startTime = {};
+    const extraFilters: Prisma.Sql[] = [];
-      if (startDate) where.startTime.gte = new Date(startDate);
+    if (startDate)  extraFilters.push(Prisma.sql`AND te.start_time >= ${new Date(startDate)}`);
-      if (endDate) where.startTime.lte = new Date(endDate);
+    if (endDate)    extraFilters.push(Prisma.sql`AND te.start_time <= ${new Date(endDate)}`);
-    }
+    if (projectId)  extraFilters.push(Prisma.sql`AND te.project_id = ${projectId}`);
+    if (clientId)   extraFilters.push(Prisma.sql`AND p.client_id = ${clientId}`);
 
-    if (projectId) {
+    const filterClause = extraFilters.length
-      where.projectId = projectId;
+      ? Prisma.join(extraFilters, " ")
-    }
+      : Prisma.empty;
 
-    if (clientId) {
+    const [projectGroups, clientGroups, totalAgg] = await Promise.all([
-      where.project = { clientId };
+      prisma.$queryRaw<
-    }
-
-    const entries = await prisma.timeEntry.findMany({
-      where,
-      include: {
-        project: {
-          select: {
-            id: true,
-            name: true,
-            color: true,
-            client: {
-              select: {
-                id: true,
-                name: true,
-              },
-            },
-          },
-        },
-      },
-    });
-
-    // Calculate total duration in seconds
-    const totalSeconds = entries.reduce((total, entry) => {
-      const startTime = new Date(entry.startTime);
-      const endTime = new Date(entry.endTime);
-      return (
-        total + Math.floor((endTime.getTime() - startTime.getTime()) / 1000)
-      );
-    }, 0);
-
-    // Calculate by project
-    const byProject = entries.reduce(
-      (acc, entry) => {
-        const projectId = entry.project.id;
-        const projectName = entry.project.name;
-        const projectColor = entry.project.color;
-        const startTime = new Date(entry.startTime);
-        const endTime = new Date(entry.endTime);
-        const duration = Math.floor(
-          (endTime.getTime() - startTime.getTime()) / 1000,
-        );
-
-        if (!acc[projectId]) {
-          acc[projectId] = {
-            projectId,
-            projectName,
-            projectColor,
-            totalSeconds: 0,
-            entryCount: 0,
-          };
-        }
-        acc[projectId].totalSeconds += duration;
-        acc[projectId].entryCount += 1;
-        return acc;
-      },
-      {} as Record<
-        string,
         {
-          projectId: string;
+          project_id: string;
-          projectName: string;
+          project_name: string;
-          projectColor: string | null;
+          project_color: string | null;
-          totalSeconds: number;
+          total_seconds: bigint;
-          entryCount: number;
+          entry_count: bigint;
-        }
+        }[]
-      >,
+      >(Prisma.sql`
-    );
+        SELECT
+          p.id   AS project_id,
+          p.name AS project_name,
+          p.color AS project_color,
+          COALESCE(SUM(EXTRACT(EPOCH FROM (te.end_time - te.start_time))), 0)::bigint AS total_seconds,
+          COUNT(te.id)::bigint AS entry_count
+        FROM time_entries te
+        JOIN projects p ON p.id = te.project_id
+        WHERE te.user_id = ${userId}
+        ${filterClause}
+        GROUP BY p.id, p.name, p.color
+        ORDER BY total_seconds DESC
+      `),
 
-    // Calculate by client
+      prisma.$queryRaw<
-    const byClient = entries.reduce(
-      (acc, entry) => {
-        const clientId = entry.project.client.id;
-        const clientName = entry.project.client.name;
-        const startTime = new Date(entry.startTime);
-        const endTime = new Date(entry.endTime);
-        const duration = Math.floor(
-          (endTime.getTime() - startTime.getTime()) / 1000,
-        );
-
-        if (!acc[clientId]) {
-          acc[clientId] = {
-            clientId,
-            clientName,
-            totalSeconds: 0,
-            entryCount: 0,
-          };
-        }
-        acc[clientId].totalSeconds += duration;
-        acc[clientId].entryCount += 1;
-        return acc;
-      },
-      {} as Record<
-        string,
         {
-          clientId: string;
+          client_id: string;
-          clientName: string;
+          client_name: string;
-          totalSeconds: number;
+          total_seconds: bigint;
-          entryCount: number;
+          entry_count: bigint;
-        }
+        }[]
-      >,
+      >(Prisma.sql`
-    );
+        SELECT
+          c.id   AS client_id,
+          c.name AS client_name,
+          COALESCE(SUM(EXTRACT(EPOCH FROM (te.end_time - te.start_time))), 0)::bigint AS total_seconds,
+          COUNT(te.id)::bigint AS entry_count
+        FROM time_entries te
+        JOIN projects p ON p.id = te.project_id
+        JOIN clients  c ON c.id = p.client_id
+        WHERE te.user_id = ${userId}
+        ${filterClause}
+        GROUP BY c.id, c.name
+        ORDER BY total_seconds DESC
+      `),
+
+      prisma.$queryRaw<{ total_seconds: bigint; entry_count: bigint }[]>(
+        Prisma.sql`
+          SELECT
+            COALESCE(SUM(EXTRACT(EPOCH FROM (te.end_time - te.start_time))), 0)::bigint AS total_seconds,
+            COUNT(te.id)::bigint AS entry_count
+          FROM time_entries te
+          JOIN projects p ON p.id = te.project_id
+          WHERE te.user_id = ${userId}
+          ${filterClause}
+        `,
+      ),
+    ]);
 
     return {
-      totalSeconds,
+      totalSeconds: Number(totalAgg[0]?.total_seconds ?? 0),
-      entryCount: entries.length,
+      entryCount: Number(totalAgg[0]?.entry_count ?? 0),
-      byProject: Object.values(byProject),
+      byProject: projectGroups.map((r) => ({
-      byClient: Object.values(byClient),
+        projectId: r.project_id,
+        projectName: r.project_name,
+        projectColor: r.project_color,
+        totalSeconds: Number(r.total_seconds),
+        entryCount: Number(r.entry_count),
+      })),
+      byClient: clientGroups.map((r) => ({
+        clientId: r.client_id,
+        clientName: r.client_name,
+        totalSeconds: Number(r.total_seconds),
+        entryCount: Number(r.entry_count),
+      })),
       filters: {
         startDate: startDate || null,
         endDate: endDate || null,
@@ -256,7 +220,7 @@ export class TimeEntryService {
     }
 
     // Check for overlapping entries
-    const hasOverlap = await this.hasOverlappingEntries(
+    const hasOverlap = await hasOverlappingEntries(
       userId,
       startTime,
       endTime,
@@ -321,7 +285,7 @@ export class TimeEntryService {
     }
 
     // Check for overlapping entries (excluding this entry)
-    const hasOverlap = await this.hasOverlappingEntries(
+    const hasOverlap = await hasOverlappingEntries(
       userId,
       startTime,
       endTime,
@@ -369,33 +333,4 @@ export class TimeEntryService {
       where: { id },
     });
   }
-
-  private async hasOverlappingEntries(
-    userId: string,
-    startTime: Date,
-    endTime: Date,
-    excludeId?: string,
-  ): Promise<boolean> {
-    const where: {
-      userId: string;
-      id?: { not: string };
-      OR: Array<{
-        startTime?: { lt: Date };
-        endTime?: { gt: Date };
-      }>;
-    } = {
-      userId,
-      OR: [
-        // Entry starts during the new entry
-        { startTime: { lt: endTime }, endTime: { gt: startTime } },
-      ],
-    };
-
-    if (excludeId) {
-      where.id = { not: excludeId };
-    }
-
-    const count = await prisma.timeEntry.count({ where });
-    return count > 0;
-  }
 }

backend/src/services/timer.service.ts

@@ -4,6 +4,7 @@ import {
   BadRequestError,
   ConflictError,
 } from "../errors/AppError";
+import { hasOverlappingEntries } from "../utils/timeUtils";
 import type {
   StartTimerInput,
   UpdateTimerInput,
@@ -155,7 +156,7 @@ export class TimerService {
     const startTime = timer.startTime;
 
     // Check for overlapping entries
-    const hasOverlap = await this.hasOverlappingEntries(
+    const hasOverlap = await hasOverlappingEntries(
       userId,
       startTime,
       endTime,
@@ -198,18 +199,4 @@ export class TimerService {
 
     return result[1]; // Return the created time entry
   }
-
-  private async hasOverlappingEntries(
-    userId: string,
-    startTime: Date,
-    endTime: Date,
-  ): Promise<boolean> {
-    const count = await prisma.timeEntry.count({
-      where: {
-        userId,
-        OR: [{ startTime: { lt: endTime }, endTime: { gt: startTime } }],
-      },
-    });
-    return count > 0;
-  }
 }

backend/src/utils/timeUtils.ts

@@ -0,0 +1,29 @@
+import { prisma } from "../prisma/client";
+
+/**
+ * Checks whether a user already has a time entry that overlaps with the given
+ * [startTime, endTime] interval.
+ *
+ * @param userId    - The user whose entries are checked.
+ * @param startTime - Start of the interval to check.
+ * @param endTime   - End of the interval to check.
+ * @param excludeId - Optional time-entry id to exclude (used when updating an
+ *                    existing entry so it does not collide with itself).
+ */
+export async function hasOverlappingEntries(
+  userId: string,
+  startTime: Date,
+  endTime: Date,
+  excludeId?: string,
+): Promise<boolean> {
+  const count = await prisma.timeEntry.count({
+    where: {
+      userId,
+      ...(excludeId ? { id: { not: excludeId } } : {}),
+      // An entry overlaps when it starts before our end AND ends after our start.
+      startTime: { lt: endTime },
+      endTime: { gt: startTime },
+    },
+  });
+  return count > 0;
+}

frontend/src/components/Modal.tsx

@@ -0,0 +1,39 @@
+import { X } from 'lucide-react';
+
+interface ModalProps {
+  title: string;
+  onClose: () => void;
+  children: React.ReactNode;
+  /** Optional override for the max-width of the modal panel (default: max-w-md) */
+  maxWidth?: string;
+}
+
+/**
+ * Generic modal overlay with a header and close button.
+ * Render form content (or any JSX) as children.
+ *
+ * @example
+ * <Modal title="Add Client" onClose={handleClose}>
+ *   <form onSubmit={handleSubmit}>...</form>
+ * </Modal>
+ */
+export function Modal({ title, onClose, children, maxWidth = 'max-w-md' }: ModalProps) {
+  return (
+    <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center p-4 z-50">
+      <div className={`bg-white rounded-lg shadow-xl ${maxWidth} w-full`}>
+        <div className="flex items-center justify-between px-6 py-4 border-b border-gray-200">
+          <h2 className="text-lg font-semibold text-gray-900">{title}</h2>
+          <button
+            type="button"
+            onClick={onClose}
+            className="p-1 text-gray-400 hover:text-gray-600 rounded"
+            aria-label="Close"
+          >
+            <X className="h-5 w-5" />
+          </button>
+        </div>
+        <div className="p-6">{children}</div>
+      </div>
+    </div>
+  );
+}

frontend/src/components/ProjectColorDot.tsx

@@ -0,0 +1,15 @@
+interface ProjectColorDotProps {
+  color: string | null | undefined;
+  /** Tailwind size classes (default: w-3 h-3) */
+  size?: string;
+}
+
+/** A small filled circle used to represent a project's colour. */
+export function ProjectColorDot({ color, size = 'w-3 h-3' }: ProjectColorDotProps) {
+  return (
+    <div
+      className={`${size} rounded-full flex-shrink-0`}
+      style={{ backgroundColor: color || '#6b7280' }}
+    />
+  );
+}

frontend/src/components/ProtectedRoute.tsx

@@ -1,5 +1,6 @@
 import { Navigate } from 'react-router-dom';
 import { useAuth } from '@/contexts/AuthContext';
+import { Spinner } from '@/components/Spinner';
 
 interface ProtectedRouteProps {
   children: React.ReactNode;
@@ -11,7 +12,7 @@ export function ProtectedRoute({ children }: ProtectedRouteProps) {
   if (isLoading) {
     return (
       <div className="min-h-screen flex items-center justify-center">
-        <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-primary-600"></div>
+        <Spinner />
       </div>
     );
   }

frontend/src/components/Spinner.tsx

@@ -0,0 +1,12 @@
+interface SpinnerProps {
+  /** Height/width class (default: h-12 w-12) */
+  size?: string;
+}
+
+export function Spinner({ size = 'h-12 w-12' }: SpinnerProps) {
+  return (
+    <div className="flex items-center justify-center h-64">
+      <div className={`animate-spin rounded-full ${size} border-b-2 border-primary-600`} />
+    </div>
+  );
+}

frontend/src/components/StatCard.tsx

@@ -0,0 +1,29 @@
+interface StatCardProps {
+  icon: React.ElementType;
+  label: string;
+  value: string;
+  color: 'blue' | 'green' | 'purple' | 'orange';
+}
+
+const colorClasses: Record<StatCardProps['color'], string> = {
+  blue: 'bg-blue-50 text-blue-600',
+  green: 'bg-green-50 text-green-600',
+  purple: 'bg-purple-50 text-purple-600',
+  orange: 'bg-orange-50 text-orange-600',
+};
+
+export function StatCard({ icon: Icon, label, value, color }: StatCardProps) {
+  return (
+    <div className="card p-4">
+      <div className="flex items-center">
+        <div className={`p-3 rounded-lg ${colorClasses[color]}`}>
+          <Icon className="h-6 w-6" />
+        </div>
+        <div className="ml-4">
+          <p className="text-sm font-medium text-gray-600">{label}</p>
+          <p className="text-2xl font-bold text-gray-900">{value}</p>
+        </div>
+      </div>
+    </div>
+  );
+}

frontend/src/components/TimerWidget.tsx

@@ -3,6 +3,7 @@ import { Play, Square, ChevronDown } from 'lucide-react';
 import { useTimer } from '@/contexts/TimerContext';
 import { useProjects } from '@/hooks/useProjects';
 import { formatDuration } from '@/utils/dateUtils';
+import { ProjectColorDot } from '@/components/ProjectColorDot';
 
 export function TimerWidget() {
   const { ongoingTimer, isLoading, elapsedSeconds, startTimer, stopTimer, updateTimerProject } = useTimer();
@@ -80,10 +81,7 @@ export function TimerWidget() {
                 >
                   {ongoingTimer.project ? (
                     <>
-                      <div
+                      <ProjectColorDot color={ongoingTimer.project.color} />
-                        className="w-3 h-3 rounded-full"
-                        style={{ backgroundColor: ongoingTimer.project.color || '#6b7280' }}
-                      />
                       <span className="text-sm font-medium text-gray-700">
                         {ongoingTimer.project.name}
                       </span>
@@ -110,10 +108,7 @@ export function TimerWidget() {
                         onClick={() => handleProjectChange(project.id)}
                         className="w-full px-4 py-2 text-left text-sm hover:bg-gray-50 flex items-center space-x-2"
                       >
-                        <div
+                        <ProjectColorDot color={project.color} />
-                          className="w-3 h-3 rounded-full flex-shrink-0"
-                          style={{ backgroundColor: project.color || '#6b7280' }}
-                        />
                         <div className="min-w-0">
                           <div className="font-medium text-gray-900 truncate">{project.name}</div>
                           <div className="text-xs text-gray-500 truncate">{project.client.name}</div>

frontend/src/pages/ClientsPage.tsx

@@ -1,6 +1,8 @@
 import { useState } from 'react';
 import { Plus, Edit2, Trash2, Building2 } from 'lucide-react';
 import { useClients } from '@/hooks/useClients';
+import { Modal } from '@/components/Modal';
+import { Spinner } from '@/components/Spinner';
 import type { Client, CreateClientInput, UpdateClientInput } from '@/types';
 
 export function ClientsPage() {
@@ -66,11 +68,7 @@ export function ClientsPage() {
   };
 
   if (isLoading) {
-    return (
+    return <Spinner />;
-      <div className="flex items-center justify-center h-64">
-        <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-primary-600"></div>
-      </div>
-    );
   }
 
   return (
@@ -145,15 +143,11 @@ export function ClientsPage() {
 
       {/* Modal */}
       {isModalOpen && (
-        <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center p-4 z-50">
+        <Modal
-          <div className="bg-white rounded-lg shadow-xl max-w-md w-full">
+          title={editingClient ? 'Edit Client' : 'Add Client'}
-            <div className="px-6 py-4 border-b border-gray-200">
+          onClose={handleCloseModal}
-              <h2 className="text-lg font-semibold text-gray-900">
+        >
-                {editingClient ? 'Edit Client' : 'Add Client'}
+          <form onSubmit={handleSubmit} className="space-y-4">
-              </h2>
-            </div>
-
-            <form onSubmit={handleSubmit} className="p-6 space-y-4">
             {error && (
               <div className="p-3 bg-red-50 text-red-700 rounded-lg text-sm">
                 {error}
@@ -204,8 +198,7 @@ export function ClientsPage() {
               </button>
             </div>
           </form>
-          </div>
+        </Modal>
-        </div>
       )}
     </div>
   );

frontend/src/pages/DashboardPage.tsx

@@ -1,10 +1,13 @@
 import { Link } from "react-router-dom";
 import { Clock, Calendar, Briefcase, TrendingUp } from "lucide-react";
 import { useTimeEntries } from "@/hooks/useTimeEntries";
+import { ProjectColorDot } from "@/components/ProjectColorDot";
+import { StatCard } from "@/components/StatCard";
 import {
   formatDate,
   formatDurationFromDates,
   formatDurationHoursMinutes,
+  calculateDuration,
 } from "@/utils/dateUtils";
 import { startOfDay, endOfDay } from "date-fns";
 
@@ -106,13 +109,8 @@ export function DashboardPage() {
                   <tr key={entry.id}>
                     <td className="px-4 py-3 whitespace-nowrap">
                       <div className="flex items-center">
-                        <div
+                        <ProjectColorDot color={entry.project.color} />
-                          className="w-3 h-3 rounded-full mr-2"
+                        <div className="ml-2">
-                          style={{
-                            backgroundColor: entry.project.color || "#6b7280",
-                          }}
-                        />
-                        <div>
                           <div className="text-sm font-medium text-gray-900">
                             {entry.project.name}
                           </div>
@@ -138,39 +136,3 @@ export function DashboardPage() {
     </div>
   );
 }
-
-interface StatCardProps {
-  icon: React.ElementType;
-  label: string;
-  value: string;
-  color: "blue" | "green" | "purple" | "orange";
-}
-
-function StatCard({ icon: Icon, label, value, color }: StatCardProps) {
-  const colors = {
-    blue: "bg-blue-50 text-blue-600",
-    green: "bg-green-50 text-green-600",
-    purple: "bg-purple-50 text-purple-600",
-    orange: "bg-orange-50 text-orange-600",
-  };
-
-  return (
-    <div className="card p-4">
-      <div className="flex items-center">
-        <div className={`p-3 rounded-lg ${colors[color]}`}>
-          <Icon className="h-6 w-6" />
-        </div>
-        <div className="ml-4">
-          <p className="text-sm font-medium text-gray-600">{label}</p>
-          <p className="text-2xl font-bold text-gray-900">{value}</p>
-        </div>
-      </div>
-    </div>
-  );
-}
-
-function calculateDuration(startTime: string, endTime: string): number {
-  return Math.floor(
-    (new Date(endTime).getTime() - new Date(startTime).getTime()) / 1000,
-  );
-}

frontend/src/pages/ProjectsPage.tsx

@@ -2,6 +2,9 @@ import { useState } from 'react';
 import { Plus, Edit2, Trash2, FolderOpen } from 'lucide-react';
 import { useProjects } from '@/hooks/useProjects';
 import { useClients } from '@/hooks/useClients';
+import { Modal } from '@/components/Modal';
+import { Spinner } from '@/components/Spinner';
+import { ProjectColorDot } from '@/components/ProjectColorDot';
 import type { Project, CreateProjectInput, UpdateProjectInput } from '@/types';
 
 const PRESET_COLORS = [
@@ -97,11 +100,7 @@ export function ProjectsPage() {
   };
 
   if (isLoading) {
-    return (
+    return <Spinner />;
-      <div className="flex items-center justify-center h-64">
-        <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-primary-600"></div>
-      </div>
-    );
   }
 
   if (!clients?.length) {
@@ -134,7 +133,7 @@ export function ProjectsPage() {
             <div className="flex items-start justify-between">
               <div className="flex-1 min-w-0">
                 <div className="flex items-center space-x-2">
-                  <div className="w-4 h-4 rounded-full" style={{ backgroundColor: project.color || '#6b7280' }} />
+                  <ProjectColorDot color={project.color} size="w-4 h-4" />
                   <h3 className="font-medium text-gray-900 truncate">{project.name}</h3>
                 </div>
                 <p className="mt-1 text-sm text-gray-500">{project.client.name}</p>
@@ -153,9 +152,10 @@ export function ProjectsPage() {
       </div>
 
       {isModalOpen && (
-        <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center p-4 z-50">
+        <Modal
-          <div className="bg-white rounded-lg shadow-xl max-w-md w-full p-6">
+          title={editingProject ? 'Edit Project' : 'Add Project'}
-            <h2 className="text-lg font-semibold mb-4">{editingProject ? 'Edit Project' : 'Add Project'}</h2>
+          onClose={handleCloseModal}
+        >
           {error && <div className="mb-4 p-3 bg-red-50 text-red-700 rounded-lg text-sm">{error}</div>}
           <form onSubmit={handleSubmit} className="space-y-4">
             <div>
@@ -184,11 +184,20 @@ export function ProjectsPage() {
             </div>
             <div className="flex justify-end space-x-3 pt-2">
               <button type="button" onClick={handleCloseModal} className="btn-secondary">Cancel</button>
-                <button type="submit" className="btn-primary">{editingProject ? 'Save' : 'Create'}</button>
+              <button
+                type="submit"
+                className="btn-primary"
+                disabled={createProject.isPending || updateProject.isPending}
+              >
+                {createProject.isPending || updateProject.isPending
+                  ? 'Saving...'
+                  : editingProject
+                  ? 'Save'
+                  : 'Create'}
+              </button>
             </div>
           </form>
-          </div>
+        </Modal>
-        </div>
       )}
     </div>
   );

frontend/src/pages/StatisticsPage.tsx

@@ -9,7 +9,8 @@ import {
 import { useStatistics } from "@/hooks/useTimeEntries";
 import { useClients } from "@/hooks/useClients";
 import { useProjects } from "@/hooks/useProjects";
-import { formatDuration } from "@/utils/dateUtils";
+import { ProjectColorDot } from "@/components/ProjectColorDot";
+import { formatDuration, toISOTimezone } from "@/utils/dateUtils";
 import type { StatisticsFilters } from "@/types";
 
 export function StatisticsPage() {
@@ -64,7 +65,7 @@ export function StatisticsPage() {
               onChange={(e) =>
                 handleFilterChange(
                   "startDate",
-                  e.target.value ? `${e.target.value}T00:00:00` : undefined,
+                  e.target.value ? toISOTimezone(`${e.target.value}T00:00:00`) : undefined,
                 )
               }
               className="input"
@@ -84,7 +85,7 @@ export function StatisticsPage() {
               onChange={(e) =>
                 handleFilterChange(
                   "endDate",
-                  e.target.value ? `${e.target.value}T23:59:59` : undefined,
+                  e.target.value ? toISOTimezone(`${e.target.value}T23:59:59`) : undefined,
                 )
               }
               className="input"
@@ -192,12 +193,7 @@ export function StatisticsPage() {
                 className="flex items-center justify-between p-3 bg-gray-50 rounded-lg"
               >
                 <div className="flex items-center gap-3">
-                  <div
+                   <ProjectColorDot color={project.projectColor} />
-                    className="w-3 h-3 rounded-full"
-                    style={{
-                      backgroundColor: project.projectColor || "#6b7280",
-                    }}
-                  />
                    <span className="font-medium text-gray-900">
                     {project.projectName}
                   </span>

frontend/src/pages/TimeEntriesPage.tsx

@@ -2,6 +2,9 @@ import { useState } from 'react';
 import { Plus, Edit2, Trash2 } from 'lucide-react';
 import { useTimeEntries } from '@/hooks/useTimeEntries';
 import { useProjects } from '@/hooks/useProjects';
+import { Modal } from '@/components/Modal';
+import { Spinner } from '@/components/Spinner';
+import { ProjectColorDot } from '@/components/ProjectColorDot';
 import { formatDate, formatDurationFromDates, getLocalISOString, toISOTimezone } from '@/utils/dateUtils';
 import type { TimeEntry, CreateTimeEntryInput, UpdateTimeEntryInput } from '@/types';
 
@@ -86,7 +89,7 @@ export function TimeEntriesPage() {
   };
 
   if (isLoading) {
-    return <div className="flex justify-center h-64 items-center"><div className="animate-spin h-12 w-12 border-b-2 border-primary-600 rounded-full"></div></div>;
+    return <Spinner />;
   }
 
   return (
@@ -117,8 +120,8 @@ export function TimeEntriesPage() {
                 <td className="px-4 py-3 whitespace-nowrap text-sm text-gray-900">{formatDate(entry.startTime)}</td>
                 <td className="px-4 py-3 whitespace-nowrap">
                   <div className="flex items-center">
-                    <div className="w-3 h-3 rounded-full mr-2" style={{ backgroundColor: entry.project.color || '#6b7280' }} />
+                    <ProjectColorDot color={entry.project.color} />
-                    <div>
+                    <div className="ml-2">
                       <div className="text-sm font-medium text-gray-900">{entry.project.name}</div>
                       <div className="text-xs text-gray-500">{entry.project.client.name}</div>
                     </div>
@@ -139,9 +142,10 @@ export function TimeEntriesPage() {
       </div>
 
       {isModalOpen && (
-        <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center p-4 z-50">
+        <Modal
-          <div className="bg-white rounded-lg shadow-xl max-w-md w-full p-6">
+          title={editingEntry ? 'Edit Entry' : 'Add Entry'}
-            <h2 className="text-lg font-semibold mb-4">{editingEntry ? 'Edit Entry' : 'Add Entry'}</h2>
+          onClose={handleCloseModal}
+        >
           {error && <div className="mb-4 p-3 bg-red-50 text-red-700 rounded-lg text-sm">{error}</div>}
           <form onSubmit={handleSubmit} className="space-y-4">
             <div>
@@ -166,11 +170,20 @@ export function TimeEntriesPage() {
             </div>
             <div className="flex justify-end space-x-3 pt-2">
               <button type="button" onClick={handleCloseModal} className="btn-secondary">Cancel</button>
-                <button type="submit" className="btn-primary">{editingEntry ? 'Save' : 'Create'}</button>
+              <button
+                type="submit"
+                className="btn-primary"
+                disabled={createTimeEntry.isPending || updateTimeEntry.isPending}
+              >
+                {createTimeEntry.isPending || updateTimeEntry.isPending
+                  ? 'Saving...'
+                  : editingEntry
+                  ? 'Save'
+                  : 'Create'}
+              </button>
             </div>
           </form>
-          </div>
+        </Modal>
-        </div>
       )}
     </div>
   );