feat(work-view): show day of week in scheduled date group headers

Display weekday alongside date when tasks are grouped by scheduled date
(e.g., "Wed 1/15" instead of "2025-01-15"), making it easier to identify
weekends at a glance.

Closes #5941

src/app/features/work-view/work-view.component.html

@@ -174,7 +174,7 @@
           @if (customized.grouped) {
             @for (group of customized.grouped | keyvalue; track group.key) {
               <collapsible
-                [title]="group.key"
+                [title]="group.key | scheduledDateGroup"
                 [isIconBefore]="true"
                 [isExpanded]="true"
               >

src/app/features/work-view/work-view.component.ts

@@ -62,6 +62,7 @@ import { TaskSharedActions } from '../../root-store/meta/task-shared.actions';
 import { TODAY_TAG } from '../tag/tag.const';
 import { LS } from '../../core/persistence/storage-keys.const';
 import { FinishDayBtnComponent } from './finish-day-btn/finish-day-btn.component';
+import { ScheduledDateGroupPipe } from '../../ui/pipes/scheduled-date-group.pipe';
 
 @Component({
   selector: 'work-view',
@@ -92,6 +93,7 @@ import { FinishDayBtnComponent } from './finish-day-btn/finish-day-btn.component
     CollapsibleComponent,
     CommonModule,
     FinishDayBtnComponent,
+    ScheduledDateGroupPipe,
   ],
 })
 export class WorkViewComponent implements OnInit, OnDestroy {

src/app/ui/pipes/scheduled-date-group.pipe.spec.ts

@@ -0,0 +1,98 @@
+import { TestBed } from '@angular/core/testing';
+import { ScheduledDateGroupPipe } from './scheduled-date-group.pipe';
+import { DateTimeFormatService } from '../../core/date-time-format/date-time-format.service';
+import { TranslateService } from '@ngx-translate/core';
+import { getDbDateStr } from '../../util/get-db-date-str';
+
+describe('ScheduledDateGroupPipe', () => {
+  let pipe: ScheduledDateGroupPipe;
+  let mockDateTimeFormatService: jasmine.SpyObj<DateTimeFormatService>;
+  let mockTranslateService: jasmine.SpyObj<TranslateService>;
+
+  beforeEach(() => {
+    mockDateTimeFormatService = jasmine.createSpyObj('DateTimeFormatService', [], {
+      currentLocale: 'en-US',
+    });
+    mockTranslateService = jasmine.createSpyObj('TranslateService', ['instant']);
+    mockTranslateService.instant.and.callFake((key: string) => {
+      if (key === 'G.TODAY_TAG_TITLE') return 'Today';
+      return key;
+    });
+
+    TestBed.configureTestingModule({
+      providers: [
+        ScheduledDateGroupPipe,
+        { provide: DateTimeFormatService, useValue: mockDateTimeFormatService },
+        { provide: TranslateService, useValue: mockTranslateService },
+      ],
+    });
+
+    pipe = TestBed.inject(ScheduledDateGroupPipe);
+  });
+
+  it('should create the pipe', () => {
+    expect(pipe).toBeTruthy();
+  });
+
+  it('should format date string with weekday', () => {
+    // Wednesday, January 15, 2025
+    const result = pipe.transform('2025-01-15');
+    expect(result).toMatch(/Wed/i);
+    expect(result).toContain('1');
+    expect(result).toContain('15');
+  });
+
+  it('should return "No date" unchanged', () => {
+    const result = pipe.transform('No date');
+    expect(result).toBe('No date');
+  });
+
+  it('should return null for null input', () => {
+    const result = pipe.transform(null);
+    expect(result).toBeNull();
+  });
+
+  it('should return null for undefined input', () => {
+    const result = pipe.transform(undefined);
+    expect(result).toBeNull();
+  });
+
+  it('should handle "Today" translation for today\'s date', () => {
+    const todayStr = getDbDateStr();
+    const result = pipe.transform(todayStr);
+    expect(result).toBe('Today');
+    expect(mockTranslateService.instant).toHaveBeenCalled();
+  });
+
+  it('should format weekend dates correctly', () => {
+    // Saturday, January 18, 2025
+    const saturdayResult = pipe.transform('2025-01-18');
+    expect(saturdayResult).toMatch(/Sat/i);
+
+    // Sunday, January 19, 2025
+    const sundayResult = pipe.transform('2025-01-19');
+    expect(sundayResult).toMatch(/Sun/i);
+  });
+
+  it('should respect configured locale for weekday names', () => {
+    // Change locale to German
+    Object.defineProperty(mockDateTimeFormatService, 'currentLocale', {
+      get: () => 'de-DE',
+    });
+
+    // Wednesday in German is "Mi" (Mittwoch)
+    const result = pipe.transform('2025-01-15');
+    expect(result).toMatch(/Mi/i);
+  });
+
+  it('should pass through non-date strings that are not "No date"', () => {
+    // "No tag", "No project" etc. should pass through unchanged
+    const result = pipe.transform('No tag');
+    expect(result).toBe('No tag');
+  });
+
+  it('should handle invalid date strings gracefully', () => {
+    const result = pipe.transform('invalid-date');
+    expect(result).toBe('invalid-date');
+  });
+});

src/app/ui/pipes/scheduled-date-group.pipe.ts

@@ -0,0 +1,57 @@
+import { inject, Pipe, PipeTransform } from '@angular/core';
+import { TranslateService } from '@ngx-translate/core';
+import { T } from 'src/app/t.const';
+import { getDbDateStr } from '../../util/get-db-date-str';
+import { dateStrToUtcDate } from '../../util/date-str-to-utc-date';
+import { DateTimeFormatService } from '../../core/date-time-format/date-time-format.service';
+
+const DATE_REGEX = /^\d{4}-\d{2}-\d{2}$/;
+
+/**
+ * Pipe that formats scheduled date group keys with day of week.
+ * Input: YYYY-MM-DD date string or special strings like "No date"
+ * Output: "Wed 1/15" or "Today" or passthrough for non-date strings
+ */
+@Pipe({
+  name: 'scheduledDateGroup',
+  standalone: true,
+  pure: false,
+})
+export class ScheduledDateGroupPipe implements PipeTransform {
+  private _dateTimeFormatService = inject(DateTimeFormatService);
+  private _translateService = inject(TranslateService);
+
+  transform(value: unknown): string | null {
+    if (value === null || value === undefined) {
+      return null;
+    }
+
+    // Ensure value is a string
+    if (typeof value !== 'string') {
+      return String(value);
+    }
+
+    // Check if it's a date string (YYYY-MM-DD format)
+    if (!DATE_REGEX.test(value)) {
+      // Pass through non-date strings like "No date", "No tag", etc.
+      return value;
+    }
+
+    const todayStr = getDbDateStr();
+    if (value === todayStr) {
+      return this._translateService.instant(T.G.TODAY_TAG_TITLE);
+    }
+
+    const date = dateStrToUtcDate(value);
+    const locale = this._dateTimeFormatService.currentLocale;
+
+    // Format with weekday and date: "Wed 1/15"
+    const formatter = new Intl.DateTimeFormat(locale, {
+      weekday: 'short',
+      month: 'numeric',
+      day: 'numeric',
+    });
+
+    return formatter.format(date);
+  }
+}