fix(locale): localize remaining ISO 8601 spelled-out date names (#8987)

Under the ISO 8601 option, dateTimeLocale is the 'sv' sync sentinel, so any
spelled-out weekday/month name rendered with currentLocale() prints in Swedish
regardless of UI language. Follow-up to #9013/#9055 covering the surfaces those
PRs didn't: spelled-out names now follow the UI language (isoTextLocale), while
numeric dates and clock times keep currentLocale().

- scheduled-list-page: locale signal -> isoTextLocale ?? currentLocale (all 6
  localeDate labels are spelled-out; fixes the reproduced 'ons, 15 juli' leak)
- dialog-focus-session-edit.formatSelectedDate: weekday+month long
- habit-tracker.dateRangeLabel: month short
- scheduled-date-group.pipe: work-view group-header tooltip weekday
- worklog (formatDayStr via mapArchiveToWorklog): day-header weekday

Inlines the isoTextLocale ?? currentLocale expression (not #9055's textLocale)
so this PR shares no files with #9055 and is conflict-free / mergeable in any
order. Adds an ISO regression test to scheduled-date-group.pipe.spec and updates
mocks so the new isoTextLocale() calls resolve. Also adds docs/handover.md.

docs/handover.md

@@ -0,0 +1,146 @@
+# Handover: ISO 8601 "spelled-out date names leak Swedish" work
+
+_Last updated: 2026-07-16. This document hands off two related, in-flight pieces of
+work to a fresh agent with no prior context._
+
+## TL;DR
+
+Super Productivity's **ISO 8601 date-format option** stores `dateTimeLocale = 'sv'`
+as a **backward-compatible sync sentinel** (it yields `YYYY-MM-DD` + a 24h clock).
+Any code that renders **spelled-out** weekday/month names (e.g. `Wed`, `July`) using
+that configured locale therefore prints them in **Swedish** (`ons`, `juli`),
+regardless of the app's UI language. The correct behavior: **spelled-out names follow
+the UI language; numeric dates and clock times keep the configured locale** (so ISO
+stays `YYYY-MM-DD` and 24h is preserved).
+
+There are two branches:
+
+| Branch | PR | Scope | State |
+| --- | --- | --- | --- |
+| `feat/https-github-com-super-productivity-su-726a40` | **#9055** | Recurring-task cluster (start-date value, quick-setting weekday, repeat-info util, add-task-bar chips) | Pushed, browser-verified, **awaiting CI + merge** |
+| `fix/iso-spelled-out-date-leaks` (**current**) | not opened yet | 5 more leak sites found during #9055 verification | Committed locally, **needs push + PR + verify** |
+
+## Background: the fix chain
+
+- **#8991 (merged, issue #8987):** localized ISO weekday labels only in the _custom_
+  Schedule/Habits/Planner components, via `DateTimeFormatService.isoTextLocale()`.
+- **#9013 (merged):** fixed the Material `<mat-calendar>` app-wide by overriding
+  `CustomDateAdapter.getDayOfWeekNames/getMonthNames/format` to swap to `isoTextLocale()`.
+- **#9055 (open):** this session's first PR — the recurring-task dialog + add-task-bar.
+- **This branch:** the remaining spelled-out leaks found by browser-testing #9055.
+
+## Key `DateTimeFormatService` API (in `src/app/core/date-time-format/`)
+
+- `currentLocale()` → the configured locale (the `sv` sentinel under ISO). Use for
+  **numeric** dates and clock times.
+- `isoTextLocale()` → `string | null`. Returns the **UI language** _only when the ISO
+  (`sv`) option is active_, else `null`. This is the shared primitive (on master).
+- `textLocale()` → `isoTextLocale() ?? currentLocale()`. **Added by #9055, NOT on master.**
+  It is the canonical "spelled-out names" locale.
+
+**Why this branch inlines `isoTextLocale() ?? currentLocale()` instead of using
+`textLocale()`:** `textLocale` only exists on the #9055 branch. To keep this PR
+**independent and conflict-free** with #9055 (no shared files, no `DateTimeFormatService`
+change, mergeable in any order), it inlines the same expression — consistent with how
+#8991/#9013 already inline `isoTextLocale` checks. After both merge, these inline
+expressions _could_ be simplified to `textLocale()`, but that is optional cleanup.
+
+## This branch's 5 fixes (`fix/iso-spelled-out-date-leaks`, based on `master`)
+
+All follow the rule **spelled-out → UI language (`isoTextLocale() ?? currentLocale()`);
+numeric → `currentLocale()`**:
+
+1. **`src/app/pages/scheduled-list-page/scheduled-list-page.component.ts`** — the `locale`
+   signal now prefers `isoTextLocale()`. All 6 `localeDate` usages in its template are
+   spelled-out (`EE, d MMM`), so this one change fixes all of them. _This is the leak that
+   was reproduced on screen: "ons, 15 juli" under German UI._
+2. **`.../metric/dialog-focus-session-edit/dialog-focus-session-edit.component.ts`** —
+   `formatSelectedDate()` (weekday `long` + month `long`) → UI language.
+3. **`.../simple-counter/habit-tracker/habit-tracker.component.ts`** — `dateRangeLabel`
+   (month `short`) → UI language. (The habit-tracker weekday _column_ was already guarded
+   by #8991; only this range label leaked.)
+4. **`src/app/ui/pipes/scheduled-date-group.pipe.ts`** — work-view group-header `[title]`
+   tooltip (weekday `short` + numeric). Low-visibility; applies UI language to the whole
+   compact formatter (documented tradeoff: the numeric part also follows UI language here
+   rather than splitting and losing the locale-native separator).
+5. **`src/app/features/worklog/worklog.service.ts`** — passes UI language into
+   `mapArchiveToWorklog` → `formatDayStr` (weekday `short` worklog day headers). Verified
+   that `locale` param feeds _only_ the spelled-out weekday there.
+
+Spec mocks updated so the new `isoTextLocale()` calls don't throw
+(`TypeError: isoTextLocale is not a function`): `scheduled-date-group.pipe.spec.ts` (+ a new
+ISO regression test) and `worklog.service.spec.ts`. The habit-tracker spec already mocked
+`isoTextLocale`.
+
+**NOT leaks (verified guarded / different mechanism — do not touch):** habit-tracker weekday
+column, planner-day `dayLabel`, schedule-week/month (all `isoTextLocale`-guarded); the
+`formatMonthDay`-based pipes (`short-planned-at`, `local-date-str`, `short-date2`) and the
+focus-session chart label are numeric; `planner-calendar-nav` uses the **browser** locale
+(`toLocaleDateString(undefined, …)`) — a separate, pre-existing, non-`sv` concern.
+
+## How the audit was done (repeat it if you suspect more leaks)
+
+A single-line `grep toLocaleDateString … currentLocale` is **insufficient** — leaks hide
+behind the `localeDate` pipe, multi-line `Intl.DateTimeFormat(locale, …)` where `locale`
+is assigned earlier, and util indirection (`formatDayStr`, `getWeekdaysMin`). Search
+instead for the **spelled-out format tokens** and then trace the locale source:
+
+```bash
+# spelled-out Intl options in .ts
+grep -rEn "weekday: *'(long|short|narrow)'|month: *'(long|short|narrow)'" src/app --include='*.ts' | grep -v spec
+# spelled-out localeDate pipe usages in templates (E / MMM / EEEE / MMMM)
+grep -rEn "localeDate: *'[^']*(E|MMM)" src/app --include='*.html'
+```
+
+For each hit, confirm whether the locale is `isoTextLocale()`-guarded (safe), the browser
+default `undefined` (separate concern), or raw `currentLocale()`/`locale()` (a leak).
+
+## Verification status
+
+- **#9055 (branch `feat/https-…-726a40`):** browser-verified against the Cloudflare PR
+  preview — recur dialog start-date value shows French `mer. 15 juil. 2026` / German
+  `Mi., 15. Juli 2026` (not Swedish), and the quick-setting dropdown shows German
+  `Jede Woche am Mittwoch`. Unit tests green; awaiting CI + merge.
+- **This branch:** unit-tested (`scheduled-date-group.pipe` 15 incl. new ISO test;
+  `habit-tracker` 4; `worklog.service` 4). **Not yet browser-verified.** No dedicated spec
+  for `scheduled-list-page` (routed page, heavy TestBed); rely on browser verification.
+
+## What's left (do these)
+
+1. **Push this branch and open the PR** (base `master`):
+   ```bash
+   # push is blocked in the sandbox; the user runs it via the `! ` prefix:
+   ! git push -u origin fix/iso-spelled-out-date-leaks
+   gh pr create --repo super-productivity/super-productivity --base master \
+     --head fix/iso-spelled-out-date-leaks \
+     --title "fix(locale): localize remaining ISO 8601 spelled-out date names (#8987)" \
+     --body-file <a body summarizing the 5 sites>
+   ```
+2. **Browser-verify this branch** on its fresh Cloudflare preview (URL is posted as a PR
+   comment ~1-2 min after push): Settings → Datetime format = **ISO 8601**, Language =
+   **Deutsch**; then check (a) the **"Wiederkehrend"** page (`/#/scheduled-list`) date labels
+   read German `Mi., 15. Juli` not `ons, 15 juli`; (b) habit-tracker range label; (c) a
+   focus-session-edit dialog date; (d) worklog day headers.
+3. **Merge order does not matter** between #9055 and this branch (no shared files). If you
+   later want the inline expressions unified to `textLocale()`, do it _after_ #9055 merges.
+4. **Re-verify #9055's round-2 surfaces** (`getTaskRepeatInfoText` repeat-info text +
+   add-task-bar date/deadline chips) on #9055's latest preview — the first verification
+   only covered its commit 1. These are unit-tested and mechanism-proven, so this is
+   confirmation, not a blocker.
+
+## Incidental finding (separate, pre-existing, NOT part of either PR)
+
+`src/assets/i18n/fr.json` uses **single-brace** placeholders (`{weekdayStr}`,
+`{dateDayStr}`, `{dayAndMonthStr}`) where ngx-translate needs **double** `{{ }}` — so the
+French recurring quick-setting labels render the literal placeholder
+("Chaque semaine le {weekdayStr}"). `en.json` and `de.json` are correct. Project rule:
+**only edit `en.json`** (other locales come from the translation pipeline), so this should
+be reported upstream, not fixed in code here.
+
+## Commands
+
+```bash
+npm run checkFile <file>                 # prettier + lint one file (run on every changed .ts)
+npm run test:file <spec>                 # single Karma spec (~real Chrome)
+git push                                 # blocked in sandbox — user runs `! git push`
+```

src/app/features/metric/dialog-focus-session-edit/dialog-focus-session-edit.component.ts

@@ -173,14 +173,16 @@ export class DialogFocusSessionEditComponent {
     const date = this.selectedDateStr();
     if (date === this.todayStr) return 'Today';
 
-    return new Date(date).toLocaleDateString(
-      this._dateTimeFormatService.currentLocale(),
-      {
-        weekday: 'long',
-        month: 'long',
-        day: 'numeric',
-      },
-    );
+    // Spelled-out weekday/month names follow the UI language under the ISO 8601
+    // option (the `sv` sentinel would otherwise leak Swedish). #8987 follow-up.
+    const textLocale =
+      this._dateTimeFormatService.isoTextLocale() ??
+      this._dateTimeFormatService.currentLocale();
+    return new Date(date).toLocaleDateString(textLocale, {
+      weekday: 'long',
+      month: 'long',
+      day: 'numeric',
+    });
   }
 
   private _getChartDates(): string[] {

src/app/features/simple-counter/habit-tracker/habit-tracker.component.ts

@@ -120,7 +120,11 @@ export class HabitTrackerComponent {
     const first = days[0].date;
     const last = days[days.length - 1].date;
 
-    const locale = this._dateTimeFormatService.currentLocale();
+    // Spelled-out `month: 'short'` name follows the UI language under the ISO
+    // 8601 option (the `sv` sentinel would otherwise leak Swedish). #8987 f/u.
+    const locale =
+      this._dateTimeFormatService.isoTextLocale() ??
+      this._dateTimeFormatService.currentLocale();
     const formatOptions: Intl.DateTimeFormatOptions = { month: 'short', day: 'numeric' };
     const firstStr = first.toLocaleDateString(locale, formatOptions);
     const lastStr = last.toLocaleDateString(locale, formatOptions);

src/app/features/worklog/worklog.service.spec.ts

@@ -86,7 +86,7 @@ describe('WorklogService context-aware loading', () => {
         },
         {
           provide: DateTimeFormatService,
-          useValue: { currentLocale: () => 'en-US' },
+          useValue: { currentLocale: () => 'en-US', isoTextLocale: () => null },
         },
       ],
     });

src/app/features/worklog/worklog.service.ts

@@ -223,7 +223,11 @@ export class WorklogService {
         nonArchiveTaskIds,
         workStartEndForWorkContext,
         this._dateAdapter.getFirstDayOfWeek(),
-        this._dateTimeFormatService.currentLocale(),
+        // Only feeds formatDayStr's spelled-out weekday, which must follow the UI
+        // language under the ISO 8601 option (the `sv` sentinel would otherwise
+        // leak Swedish weekday names in worklog day headers). #8987 follow-up.
+        this._dateTimeFormatService.isoTextLocale() ??
+          this._dateTimeFormatService.currentLocale(),
       );
       return {
         worklog,

src/app/pages/scheduled-list-page/scheduled-list-page.component.ts

@@ -1,4 +1,4 @@
-import { ChangeDetectionStrategy, Component, inject } from '@angular/core';
+import { ChangeDetectionStrategy, Component, computed, inject } from '@angular/core';
 import { T } from '../../t.const';
 import { MatDialog } from '@angular/material/dialog';
 import { TaskCopy } from '../../features/tasks/task.model';
@@ -66,8 +66,16 @@ export class ScheduledListPageComponent {
   private _taskRepeatCfgService = inject(TaskRepeatCfgService);
   private _dateTimeFormatService = inject(DateTimeFormatService);
   // Exposed so the template can pass the reactive locale to the now-pure
-  // `localeDate` pipe, preserving re-render on a locale change.
-  readonly locale = this._dateTimeFormatService.currentLocale;
+  // `localeDate` pipe, preserving re-render on a locale change. Every localeDate
+  // usage on this page renders spelled-out weekday/month names (e.g. 'EE, d MMM'),
+  // so under the ISO 8601 option we follow the UI language (isoTextLocale) rather
+  // than the `sv` sentinel — which would otherwise leak Swedish ("ons, 15 juli").
+  // #8987 follow-up.
+  readonly locale = computed(
+    () =>
+      this._dateTimeFormatService.isoTextLocale() ??
+      this._dateTimeFormatService.currentLocale(),
+  );
   T: typeof T = T;
   TODAY_TAG: Tag = TODAY_TAG;
   taskRepeatCfgs$ = this._store.select(selectTaskRepeatCfgsSortedByTitleAndProject);

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

@@ -12,6 +12,8 @@ describe('ScheduledDateGroupPipe', () => {
   beforeEach(() => {
     mockDateTimeFormatService = jasmine.createSpyObj('DateTimeFormatService', [], {
       currentLocale: () => 'en-US',
+      // null = non-ISO option: the pipe falls back to currentLocale.
+      isoTextLocale: () => null,
     });
     mockTranslateService = jasmine.createSpyObj('TranslateService', ['instant']);
     mockTranslateService.instant.and.callFake((key: string) => {
@@ -110,6 +112,22 @@ describe('ScheduledDateGroupPipe', () => {
     expect(result).toMatch(/Mi/i);
   });
 
+  it('should follow the UI language (isoTextLocale) for the weekday under the ISO option (#8987)', () => {
+    // ISO 8601 option: currentLocale is the sv sentinel, but isoTextLocale
+    // carries the UI language ('de-DE'); the weekday must not leak Swedish.
+    Object.defineProperty(mockDateTimeFormatService, 'currentLocale', {
+      get: () => () => 'sv',
+    });
+    Object.defineProperty(mockDateTimeFormatService, 'isoTextLocale', {
+      get: () => () => 'de-DE',
+    });
+
+    // Wednesday 2025-01-15 → German "Mi", not Swedish "ons".
+    const result = pipe.transform('2025-01-15');
+    expect(result).toMatch(/Mi/i);
+    expect(result).not.toMatch(/ons/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');

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

@@ -42,7 +42,14 @@ export class ScheduledDateGroupPipe implements PipeTransform {
     }
 
     const date = dateStrToUtcDate(value);
-    const locale = this._dateTimeFormatService.currentLocale();
+    // The spelled-out weekday must follow the UI language under the ISO 8601
+    // option (the `sv` sentinel would otherwise leak Swedish, e.g. "ons 15/1").
+    // This is a compact group-header label, so the whole (short) format follows
+    // the UI language when ISO is active rather than splitting weekday vs numeric
+    // and losing the locale-native separator. #8987 follow-up.
+    const locale =
+      this._dateTimeFormatService.isoTextLocale() ??
+      this._dateTimeFormatService.currentLocale();
 
     // Format with weekday and date: "Wed 1/15"
     const formatter = new Intl.DateTimeFormat(locale, {