backend/src/routes/timer.routes.ts

@@ -48,6 +48,16 @@ router.put(
   }
 );
 
+// DELETE /api/timer - Cancel (discard) the ongoing timer without creating a time entry
+router.delete('/', requireAuth, async (req: AuthenticatedRequest, res, next) => {
+  try {
+    await timerService.cancel(req.user!.id);
+    res.status(204).send();
+  } catch (error) {
+    next(error);
+  }
+});
+
 // POST /api/timer/stop - Stop timer
 router.post(
   '/stop',

backend/src/schemas/index.ts

@@ -64,6 +64,7 @@ export const StartTimerSchema = z.object({
 
 export const UpdateTimerSchema = z.object({
   projectId: z.string().uuid().optional().nullable(),
+  startTime: z.string().datetime().optional(),
 });
 
 export const StopTimerSchema = z.object({

backend/src/services/timer.service.ts

@@ -102,9 +102,24 @@ export class TimerService {
       projectId = data.projectId;
     }
 
+    // Validate startTime if provided
+    let startTime: Date | undefined = undefined;
+    if (data.startTime) {
+      const parsed = new Date(data.startTime);
+      const now = new Date();
+      if (parsed >= now) {
+        throw new BadRequestError("Start time must be in the past");
+      }
+      startTime = parsed;
+    }
+
+    const updateData: Record<string, unknown> = {};
+    if (projectId !== undefined) updateData.projectId = projectId;
+    if (startTime !== undefined) updateData.startTime = startTime;
+
     return prisma.ongoingTimer.update({
       where: { userId },
-      data: projectId !== undefined ? { projectId } : {},
+      data: updateData,
       include: {
         project: {
           select: {
@@ -123,6 +138,15 @@ export class TimerService {
     });
   }
 
+  async cancel(userId: string) {
+    const timer = await this.getOngoingTimer(userId);
+    if (!timer) {
+      throw new NotFoundError("No timer is running");
+    }
+
+    await prisma.ongoingTimer.delete({ where: { userId } });
+  }
+
   async stop(userId: string, data?: StopTimerInput) {
     const timer = await this.getOngoingTimer(userId);
     if (!timer) {

backend/src/types/index.ts

@@ -71,6 +71,7 @@ export interface StartTimerInput {
 
 export interface UpdateTimerInput {
   projectId?: string | null;
+  startTime?: string;
 }
 
 export interface StopTimerInput {

frontend/src/api/timer.ts

@@ -1,6 +1,11 @@
 import apiClient from './client';
 import type { OngoingTimer, TimeEntry } from '@/types';
 
+export interface UpdateTimerPayload {
+  projectId?: string | null;
+  startTime?: string;
+}
+
 export const timerApi = {
   getOngoing: async (): Promise<OngoingTimer | null> => {
     const { data } = await apiClient.get<OngoingTimer | null>('/timer');
@@ -14,10 +19,8 @@ export const timerApi = {
     return data;
   },
 
-  update: async (projectId?: string | null): Promise<OngoingTimer> => {
+  update: async (payload: UpdateTimerPayload): Promise<OngoingTimer> => {
-    const { data } = await apiClient.put<OngoingTimer>('/timer', {
+    const { data } = await apiClient.put<OngoingTimer>('/timer', payload);
-      projectId,
-    });
     return data;
   },
 
@@ -27,4 +30,8 @@ export const timerApi = {
     });
     return data;
   },
+
+  cancel: async (): Promise<void> => {
+    await apiClient.delete('/timer');
+  },
 };

frontend/src/components/Navbar.tsx

@@ -48,7 +48,7 @@ export function Navbar() {
         <div className="flex justify-between h-16">
           <div className="flex">
             <div className="flex-shrink-0 flex items-center">
-              <Clock className="h-8 w-8 text-primary-600" />
+              <img src="/icon.svg" alt="TimeTracker Logo" className="h-8 w-8 drop-shadow-sm" />
               <span className="ml-2 text-xl font-bold text-gray-900">
                 TimeTracker
               </span>

frontend/src/components/TimerWidget.tsx

@@ -1,5 +1,5 @@
-import { useState } from "react";
+import { useState, useRef } from "react";
-import { Play, Square, ChevronDown } from "lucide-react";
+import { Play, Square, ChevronDown, Pencil, Check, X, Trash2 } from "lucide-react";
 import { useTimer } from "@/contexts/TimerContext";
 import { useProjects } from "@/hooks/useProjects";
 import { ProjectColorDot } from "@/components/ProjectColorDot";
@@ -27,6 +27,21 @@ function TimerDisplay({ totalSeconds }: { totalSeconds: number }) {
   );
 }
 
+/** Converts a HH:mm string to an ISO datetime, inferring the correct date.
+ *  If the resulting time would be in the future, it is assumed to belong to the previous day.
+ */
+function timeInputToIso(timeValue: string): string {
+  const [hours, minutes] = timeValue.split(":").map(Number);
+  const now = new Date();
+  const candidate = new Date(now);
+  candidate.setHours(hours, minutes, 0, 0);
+  // If the candidate is in the future, roll back one day
+  if (candidate > now) {
+    candidate.setDate(candidate.getDate() - 1);
+  }
+  return candidate.toISOString();
+}
+
 export function TimerWidget() {
   const {
     ongoingTimer,
@@ -34,12 +49,19 @@ export function TimerWidget() {
     elapsedSeconds,
     startTimer,
     stopTimer,
+    cancelTimer,
     updateTimerProject,
+    updateTimerStartTime,
   } = useTimer();
   const { projects } = useProjects();
   const [showProjectSelect, setShowProjectSelect] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
+  // Start time editing state
+  const [editingStartTime, setEditingStartTime] = useState(false);
+  const [startTimeInput, setStartTimeInput] = useState("");
+  const startTimeInputRef = useRef<HTMLInputElement>(null);
+
   const handleStart = async () => {
     setError(null);
     try {
@@ -58,6 +80,15 @@ export function TimerWidget() {
     }
   };
 
+  const handleCancelTimer = async () => {
+    setError(null);
+    try {
+      await cancelTimer();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : "Failed to cancel timer");
+    }
+  };
+
   const handleProjectChange = async (projectId: string) => {
     setError(null);
     try {
@@ -78,6 +109,42 @@ export function TimerWidget() {
     }
   };
 
+  const handleStartEditStartTime = () => {
+    if (!ongoingTimer) return;
+    const start = new Date(ongoingTimer.startTime);
+    const hh = start.getHours().toString().padStart(2, "0");
+    const mm = start.getMinutes().toString().padStart(2, "0");
+    setStartTimeInput(`${hh}:${mm}`);
+    setEditingStartTime(true);
+    // Focus the input on next render
+    setTimeout(() => startTimeInputRef.current?.focus(), 0);
+  };
+
+  const handleCancelEditStartTime = () => {
+    setEditingStartTime(false);
+    setError(null);
+  };
+
+  const handleConfirmStartTime = async () => {
+    if (!startTimeInput) return;
+    setError(null);
+    try {
+      const iso = timeInputToIso(startTimeInput);
+      await updateTimerStartTime(iso);
+      setEditingStartTime(false);
+    } catch (err) {
+      setError(err instanceof Error ? err.message : "Failed to update start time");
+    }
+  };
+
+  const handleStartTimeKeyDown = (e: React.KeyboardEvent<HTMLInputElement>) => {
+    if (e.key === "Enter") {
+      void handleConfirmStartTime();
+    } else if (e.key === "Escape") {
+      handleCancelEditStartTime();
+    }
+  };
+
   if (isLoading) {
     return (
       <div className="fixed bottom-0 left-0 right-0 bg-white border-t border-gray-200 py-4 shadow-lg">
@@ -95,21 +162,69 @@ export function TimerWidget() {
           <>
             {/* Row 1 (mobile): timer + stop side by side. On sm+ dissolves into the parent flex row via contents. */}
             <div className="flex items-center justify-between w-full sm:contents">
-              {/* Timer Display */}
+              {/* Timer Display + Start Time Editor */}
               <div className="flex items-center space-x-2 shrink-0">
                 <div className="w-3 h-3 bg-red-500 rounded-full animate-pulse"></div>
+                {editingStartTime ? (
+                  <div className="flex items-center space-x-1">
+                    <span className="text-xs text-gray-500 mr-1">Started at</span>
+                    <input
+                      ref={startTimeInputRef}
+                      type="time"
+                      value={startTimeInput}
+                      onChange={(e) => setStartTimeInput(e.target.value)}
+                      onKeyDown={handleStartTimeKeyDown}
+                      className="font-mono text-lg font-bold text-gray-900 border border-primary-400 rounded px-2 py-0.5 focus:outline-none focus:ring-2 focus:ring-primary-500 w-28"
+                    />
+                    <button
+                      onClick={() => void handleConfirmStartTime()}
+                      title="Confirm"
+                      className="p-1 text-green-600 hover:text-green-700 hover:bg-green-50 rounded"
+                    >
+                      <Check className="h-4 w-4" />
+                    </button>
+                    <button
+                      onClick={handleCancelEditStartTime}
+                      title="Cancel"
+                      className="p-1 text-gray-400 hover:text-gray-600 hover:bg-gray-100 rounded"
+                    >
+                      <X className="h-4 w-4" />
+                    </button>
+                  </div>
+                ) : (
+                  <div className="flex items-center space-x-2">
                     <TimerDisplay totalSeconds={elapsedSeconds} />
+                    <button
+                      onClick={handleStartEditStartTime}
+                      title="Adjust start time"
+                      className="p-1 text-gray-400 hover:text-gray-600 hover:bg-gray-100 rounded transition-colors"
+                    >
+                      <Pencil className="h-3.5 w-3.5" />
+                    </button>
+                  </div>
+                )}
               </div>
 
-              {/* Stop Button */}
+              {/* Stop + Cancel Buttons */}
+              <div className="flex items-center space-x-2 shrink-0 sm:order-last">
+                <button
+                  onClick={() => void handleCancelTimer()}
+                  title="Discard timer"
+                  className="p-2 text-gray-400 hover:text-gray-600 hover:bg-gray-100 rounded-lg transition-colors"
+                >
+                  <Trash2 className="h-5 w-5" />
+                </button>
                 <button
                   onClick={handleStop}
-                className="flex items-center space-x-2 px-6 py-3 bg-red-600 text-white rounded-lg font-medium hover:bg-red-700 transition-colors shrink-0 sm:order-last"
+                  disabled={!ongoingTimer.project}
+                  title={!ongoingTimer.project ? "Select a project to stop the timer" : undefined}
+                  className="flex items-center space-x-2 px-6 py-3 bg-red-600 text-white rounded-lg font-medium hover:bg-red-700 transition-colors disabled:opacity-40 disabled:cursor-not-allowed disabled:hover:bg-red-600"
                 >
                   <Square className="h-5 w-5 fill-current" />
                   <span>Stop</span>
                 </button>
               </div>
+            </div>
 
             {/* Project Selector — full width on mobile, auto on desktop */}
             <div className="relative w-full sm:w-auto sm:flex-1 sm:mx-4">

frontend/src/contexts/TimerContext.tsx

@@ -17,6 +17,8 @@ interface TimerContextType {
   elapsedSeconds: number;
   startTimer: (projectId?: string) => Promise<void>;
   updateTimerProject: (projectId?: string | null) => Promise<void>;
+  updateTimerStartTime: (startTime: string) => Promise<void>;
+  cancelTimer: () => Promise<void>;
   stopTimer: (projectId?: string) => Promise<TimeEntry | null>;
 }
 
@@ -84,6 +86,14 @@ export function TimerProvider({ children }: { children: ReactNode }) {
     },
   });
 
+  // Cancel timer mutation
+  const cancelMutation = useMutation({
+    mutationFn: timerApi.cancel,
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["ongoingTimer"] });
+    },
+  });
+
   // Stop timer mutation
   const stopMutation = useMutation({
     mutationFn: timerApi.stop,
@@ -102,11 +112,22 @@ export function TimerProvider({ children }: { children: ReactNode }) {
 
   const updateTimerProject = useCallback(
     async (projectId?: string | null) => {
-      await updateMutation.mutateAsync(projectId);
+      await updateMutation.mutateAsync({ projectId });
     },
     [updateMutation],
   );
 
+  const updateTimerStartTime = useCallback(
+    async (startTime: string) => {
+      await updateMutation.mutateAsync({ startTime });
+    },
+    [updateMutation],
+  );
+
+  const cancelTimer = useCallback(async () => {
+    await cancelMutation.mutateAsync();
+  }, [cancelMutation]);
+
   const stopTimer = useCallback(
     async (projectId?: string): Promise<TimeEntry | null> => {
       try {
@@ -127,6 +148,8 @@ export function TimerProvider({ children }: { children: ReactNode }) {
         elapsedSeconds,
         startTimer,
         updateTimerProject,
+        updateTimerStartTime,
+        cancelTimer,
         stopTimer,
       }}
     >

frontend/src/pages/LoginPage.tsx

@@ -1,4 +1,3 @@
-import { Clock } from 'lucide-react';
 import { useAuth } from '@/contexts/AuthContext';
 
 export function LoginPage() {
@@ -8,8 +7,8 @@ export function LoginPage() {
     <div className="min-h-screen flex items-center justify-center bg-gray-50">
       <div className="max-w-md w-full space-y-8 p-8">
         <div className="text-center">
-          <div className="mx-auto h-16 w-16 bg-primary-100 rounded-full flex items-center justify-center">
+          <div className="mx-auto h-16 w-16 flex items-center justify-center drop-shadow-sm">
-            <Clock className="h-8 w-8 text-primary-600" />
+            <img src="/icon.svg" alt="TimeTracker Logo" className="h-16 w-16" />
           </div>
           <h2 className="mt-6 text-3xl font-bold text-gray-900">TimeTracker</h2>
           <p className="mt-2 text-sm text-gray-600">