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+# Back Button + Flight Schedule Timeline (B.6) Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Add Angular-parity navigation (back button in header) and a schedule timeline (accordion with scheduled times + duration + days-of-week strip + week date-range note) to the React Online Board details page.
+
+**Architecture:** Two independent feature directories. `DetailsBackButton` is a simple `<Link>`. `FlightSchedule` is a PrimeReact `Accordion` wrapping a Schedule tab, plus a persistent days-of-week strip below. A small `weekDateRange` helper uses `date-fns` ISO week functions. `IFlightLeg` gains an optional `daysOfWeek` field.
+
+**Tech Stack:** React 18, PrimeReact `Accordion` + `AccordionTab`, `date-fns` (`startOfISOWeek`, `endOfISOWeek`, `parseISO`, `format`), React Router `<Link>`, Vitest + React Testing Library.
+
+---
+
+## File Structure
+
+### New files
+
+- `src/features/online-board/components/DetailsBackButton/DetailsBackButton.tsx`
+- `src/features/online-board/components/DetailsBackButton/DetailsBackButton.scss`
+- `src/features/online-board/components/DetailsBackButton/DetailsBackButton.test.tsx`
+- `src/features/online-board/components/DetailsBackButton/index.ts`
+- `src/features/online-board/components/FlightSchedule/weekDateRange.ts`
+- `src/features/online-board/components/FlightSchedule/weekDateRange.test.ts`
+- `src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.tsx`
+- `src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.test.tsx`
+- `src/features/online-board/components/FlightSchedule/FlightSchedule.tsx`
+- `src/features/online-board/components/FlightSchedule/FlightSchedule.scss`
+- `src/features/online-board/components/FlightSchedule/FlightSchedule.test.tsx`
+- `src/features/online-board/components/FlightSchedule/index.ts`
+
+### Modified files
+
+- `src/features/online-board/types.ts` — add `IDaysOfWeek`, extend `IFlightLeg` with optional `daysOfWeek`
+- `src/features/online-board/types.test.ts` — add test case
+- `src/features/online-board/components/OnlineBoardDetailsPage.tsx` — swap PageTabs→DetailsBackButton, insert FlightSchedule
+- `src/features/online-board/components/OnlineBoardDetailsPage.test.tsx` — update mocks/assertions
+
+---
+
+### Task 1: Extend `IFlightLeg` with `daysOfWeek`
+
+**Files:**
+- Modify: `src/features/online-board/types.ts`
+- Modify: `src/features/online-board/types.test.ts`
+
+- [ ] **Step 1: Add failing test**
+
+Append to `src/features/online-board/types.test.ts` inside the existing `describe("online-board types extension")` block:
+
+```typescript
+  it("IDaysOfWeek has current and flight bit strings", () => {
+    const d: IDaysOfWeek = { current: "1000010", flight: "1111111" };
+    expect(d.current).toBe("1000010");
+    expect(d.flight).toBe("1111111");
+  });
+
+  it("IFlightLeg accepts optional daysOfWeek", () => {
+    const leg: Partial<IFlightLeg> = {
+      daysOfWeek: { current: "1000010", flight: "1111111" },
+    };
+    expect(leg.daysOfWeek?.flight).toBe("1111111");
+  });
+```
+
+Also update the imports at the top of `types.test.ts` to include `IDaysOfWeek`:
+
+Find the existing `import type {` block and add `IDaysOfWeek,` to the list.
+
+- [ ] **Step 2: Run test to verify fail**
+
+Run: `pnpm vitest run src/features/online-board/types.test.ts`
+
+Expected: FAIL — `IDaysOfWeek` is not exported.
+
+- [ ] **Step 3: Extend `src/features/online-board/types.ts`**
+
+Add a new exported interface near the `IFlightLegFlags` (just before the `IFlightLeg` definition):
+
+```typescript
+// ---------------------------------------------------------------------------
+// Days of week
+// ---------------------------------------------------------------------------
+
+/**
+ * Bit-string indicator of flight operation days.
+ * Position 0 = Monday, position 6 = Sunday. `"1"` means active.
+ */
+export interface IDaysOfWeek {
+  current: string;
+  flight: string;
+}
+```
+
+Then add `daysOfWeek?: IDaysOfWeek;` to the `IFlightLeg` interface (add at the end, preserving other fields):
+
+```typescript
+export interface IFlightLeg {
+  arrival: IFlightLegArrivalStation;
+  dayChange: number;
+  departure: IFlightLegDepartureStation;
+  equipment: { name?: string; code?: string } & IEquipmentFull;
+  flags: IFlightLegFlags;
+  flyingTime: string;
+  index: number;
+  operatingBy: { carrier?: string; flightNumber?: string };
+  status: FlightStatus;
+  updated: string;
+  transition?: IFlightTransitions;
+  daysOfWeek?: IDaysOfWeek;
+}
+```
+
+- [ ] **Step 4: Run test to verify pass**
+
+Run: `pnpm vitest run src/features/online-board/types.test.ts`
+
+Expected: all tests pass.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/features/online-board/types.ts src/features/online-board/types.test.ts
+git commit -m "Extend IFlightLeg with optional daysOfWeek field"
+```
+
+---
+
+### Task 2: `weekDateRange` Helper
+
+**Files:**
+- Create: `src/features/online-board/components/FlightSchedule/weekDateRange.ts`
+- Create: `src/features/online-board/components/FlightSchedule/weekDateRange.test.ts`
+
+- [ ] **Step 1: Write failing test**
+
+```typescript
+// weekDateRange.test.ts
+import { describe, it, expect } from "vitest";
+import { getWeekDateRange } from "./weekDateRange.js";
+
+describe("getWeekDateRange", () => {
+  it("returns Monday/Sunday for a mid-week date", () => {
+    // 2026-04-15 is a Wednesday
+    const result = getWeekDateRange("2026-04-15T10:00:00");
+    expect(result.start).toBe("13.04.2026"); // Monday
+    expect(result.end).toBe("19.04.2026");   // Sunday
+  });
+
+  it("returns Monday/Sunday for a Sunday input (same ISO week)", () => {
+    // 2026-04-19 is a Sunday
+    const result = getWeekDateRange("2026-04-19T10:00:00");
+    expect(result.start).toBe("13.04.2026");
+    expect(result.end).toBe("19.04.2026");
+  });
+
+  it("returns Monday/Sunday for a Monday input", () => {
+    const result = getWeekDateRange("2026-04-13T10:00:00");
+    expect(result.start).toBe("13.04.2026");
+    expect(result.end).toBe("19.04.2026");
+  });
+
+  it("returns empty strings for invalid input", () => {
+    const result = getWeekDateRange("not-a-date");
+    expect(result).toEqual({ start: "", end: "" });
+  });
+
+  it("returns empty strings for undefined input", () => {
+    const result = getWeekDateRange(undefined);
+    expect(result).toEqual({ start: "", end: "" });
+  });
+});
+```
+
+- [ ] **Step 2: Verify fail**
+
+Run: `pnpm vitest run src/features/online-board/components/FlightSchedule/weekDateRange.test.ts`
+
+Expected: FAIL.
+
+- [ ] **Step 3: Create `weekDateRange.ts`**
+
+```typescript
+import { parseISO, startOfISOWeek, endOfISOWeek, format, isValid } from "date-fns";
+
+/**
+ * Given a scheduled local-time ISO string, return the ISO-week bounds
+ * (Monday/Sunday) as `dd.MM.yyyy` formatted strings.
+ * Returns `{ start: "", end: "" }` for invalid or missing input.
+ */
+export function getWeekDateRange(scheduledLocal: string | undefined): {
+  start: string;
+  end: string;
+} {
+  if (!scheduledLocal) return { start: "", end: "" };
+  const d = parseISO(scheduledLocal);
+  if (!isValid(d)) return { start: "", end: "" };
+  return {
+    start: format(startOfISOWeek(d), "dd.MM.yyyy"),
+    end: format(endOfISOWeek(d), "dd.MM.yyyy"),
+  };
+}
+```
+
+- [ ] **Step 4: Verify pass**
+
+Run: `pnpm vitest run src/features/online-board/components/FlightSchedule/weekDateRange.test.ts`
+
+Expected: 5 tests pass.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/features/online-board/components/FlightSchedule/weekDateRange.ts src/features/online-board/components/FlightSchedule/weekDateRange.test.ts
+git commit -m "Add weekDateRange helper for flight schedule note"
+```
+
+---
+
+### Task 3: `DaysOfWeekStrip` Component
+
+**Files:**
+- Create: `src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.tsx`
+- Create: `src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.test.tsx`
+
+- [ ] **Step 1: Write failing test**
+
+```tsx
+// @vitest-environment jsdom
+import { describe, it, expect, vi } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { DaysOfWeekStrip } from "./DaysOfWeekStrip.js";
+
+vi.mock("@/i18n/provider.js", () => ({
+  useTranslation: () => ({ t: (k: string) => k }),
+}));
+
+describe("DaysOfWeekStrip", () => {
+  it("renders 7 day boxes", () => {
+    render(<DaysOfWeekStrip flightBitString="1111111" />);
+    const boxes = screen.getAllByTestId(/^day-of-week-\d$/);
+    expect(boxes).toHaveLength(7);
+  });
+
+  it("marks first 3 active, last 4 inactive for '1110000'", () => {
+    render(<DaysOfWeekStrip flightBitString="1110000" />);
+    expect(screen.getByTestId("day-of-week-0").className).not.toMatch(/--inactive/);
+    expect(screen.getByTestId("day-of-week-1").className).not.toMatch(/--inactive/);
+    expect(screen.getByTestId("day-of-week-2").className).not.toMatch(/--inactive/);
+    expect(screen.getByTestId("day-of-week-3").className).toMatch(/--inactive/);
+    expect(screen.getByTestId("day-of-week-6").className).toMatch(/--inactive/);
+  });
+
+  it("marks all active for '1111111'", () => {
+    render(<DaysOfWeekStrip flightBitString="1111111" />);
+    for (let i = 0; i < 7; i++) {
+      expect(screen.getByTestId(`day-of-week-${i}`).className).not.toMatch(/--inactive/);
+    }
+  });
+
+  it("marks all inactive for '0000000'", () => {
+    render(<DaysOfWeekStrip flightBitString="0000000" />);
+    for (let i = 0; i < 7; i++) {
+      expect(screen.getByTestId(`day-of-week-${i}`).className).toMatch(/--inactive/);
+    }
+  });
+
+  it("renders DAYS.1 through DAYS.7 labels in order", () => {
+    render(<DaysOfWeekStrip flightBitString="1111111" />);
+    expect(screen.getByTestId("day-of-week-0").textContent).toContain("DAYS.1");
+    expect(screen.getByTestId("day-of-week-6").textContent).toContain("DAYS.7");
+  });
+});
+```
+
+- [ ] **Step 2: Verify fail**
+
+Run: `pnpm vitest run src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.test.tsx`
+
+Expected: FAIL.
+
+- [ ] **Step 3: Create `DaysOfWeekStrip.tsx`**
+
+```tsx
+import type { FC } from "react";
+import { useTranslation } from "@/i18n/provider.js";
+
+export interface DaysOfWeekStripProps {
+  flightBitString: string;
+}
+
+const DAY_INDEXES = [0, 1, 2, 3, 4, 5, 6] as const;
+
+export const DaysOfWeekStrip: FC<DaysOfWeekStripProps> = ({ flightBitString }) => {
+  const { t } = useTranslation();
+
+  return (
+    <div className="days-of-week-strip">
+      {DAY_INDEXES.map((i) => {
+        const isActive = flightBitString[i] === "1";
+        const className = isActive ? "day" : "day day--inactive";
+        return (
+          <span
+            key={i}
+            className={className}
+            data-testid={`day-of-week-${i}`}
+          >
+            {t(`DAYS.${i + 1}`)}
+          </span>
+        );
+      })}
+    </div>
+  );
+};
+```
+
+- [ ] **Step 4: Verify pass**
+
+Run: `pnpm vitest run src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.test.tsx`
+
+Expected: 5 tests pass.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.tsx src/features/online-board/components/FlightSchedule/DaysOfWeekStrip.test.tsx
+git commit -m "Add DaysOfWeekStrip component for flight schedule"
+```
+
+---
+
+### Task 4: `FlightSchedule` Component + SCSS + Barrel
+
+**Files:**
+- Create: `src/features/online-board/components/FlightSchedule/FlightSchedule.tsx`
+- Create: `src/features/online-board/components/FlightSchedule/FlightSchedule.scss`
+- Create: `src/features/online-board/components/FlightSchedule/FlightSchedule.test.tsx`
+- Create: `src/features/online-board/components/FlightSchedule/index.ts`
+
+- [ ] **Step 1: Write failing test**
+
+```tsx
+// @vitest-environment jsdom
+import { describe, it, expect, vi } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { FlightSchedule } from "./FlightSchedule.js";
+import type { ISimpleFlight } from "../../types.js";
+
+vi.mock("@/i18n/provider.js", () => ({
+  useTranslation: () => ({
+    t: (k: string) => {
+      if (k === "SHARED.NOTE-TIME-SCHEDULE") {
+        return "Valid from {START_DATE} to {END_DATE}";
+      }
+      return k;
+    },
+  }),
+}));
+
+function makeFlight(overrides: { daysOfWeek?: { current: string; flight: string } }): ISimpleFlight {
+  return {
+    id: "X", routeType: "Direct", flyingTime: "2h 30m", status: "Scheduled",
+    flightId: { carrier: "SU", flightNumber: "0022", suffix: "", date: "20260415" },
+    operatingBy: { carrier: "SU", flightNumber: "0022" },
+    leg: {
+      arrival: {
+        scheduled: { airport: "LED", airportCode: "LED", city: "SPB", cityCode: "LED", countryCode: "RU" },
+        latest: { airport: "LED", airportCode: "LED", city: "SPB", cityCode: "LED", countryCode: "RU" },
+        dispatch: "", gate: "", terminal: "",
+        times: { scheduledArrival: { dayChange: { value: 0, title: "" }, local: "12:30", localTime: "", tzOffset: 0, utc: "" } },
+      },
+      dayChange: 0,
+      departure: {
+        scheduled: { airport: "SVO", airportCode: "SVO", city: "MOW", cityCode: "MOW", countryCode: "RU" },
+        latest: { airport: "SVO", airportCode: "SVO", city: "MOW", cityCode: "MOW", countryCode: "RU" },
+        dispatch: "", gate: "", terminal: "", checkingStatus: "Scheduled", parkingStand: "",
+        times: { scheduledDeparture: { dayChange: { value: 0, title: "" }, local: "2026-04-15T10:00:00", localTime: "10:00", tzOffset: 0, utc: "" } },
+      },
+      equipment: {},
+      flags: { checkinAvailable: false, returnToAirport: false, routeChanged: false },
+      flyingTime: "2h 30m", index: 0, operatingBy: {}, status: "Scheduled", updated: "",
+      ...overrides,
+    },
+  } as ISimpleFlight;
+}
+
+describe("FlightSchedule", () => {
+  it("returns null when firstLeg has no daysOfWeek", () => {
+    const { container } = render(<FlightSchedule flight={makeFlight({})} />);
+    expect(container.firstChild).toBeNull();
+  });
+
+  it("returns null when daysOfWeek.flight is empty string", () => {
+    const { container } = render(
+      <FlightSchedule flight={makeFlight({ daysOfWeek: { current: "0000000", flight: "" } })} />,
+    );
+    expect(container.firstChild).toBeNull();
+  });
+
+  it("renders with data-testid=flight-schedule when daysOfWeek present", () => {
+    render(
+      <FlightSchedule flight={makeFlight({ daysOfWeek: { current: "1000010", flight: "1111111" } })} />,
+    );
+    expect(screen.getByTestId("flight-schedule")).toBeTruthy();
+  });
+
+  it("renders 7 day boxes from daysOfWeek.flight", () => {
+    render(
+      <FlightSchedule flight={makeFlight({ daysOfWeek: { current: "1000010", flight: "1110000" } })} />,
+    );
+    const boxes = screen.getAllByTestId(/^day-of-week-\d$/);
+    expect(boxes).toHaveLength(7);
+  });
+
+  it("substitutes {START_DATE} and {END_DATE} into the note", () => {
+    render(
+      <FlightSchedule flight={makeFlight({ daysOfWeek: { current: "1000010", flight: "1111111" } })} />,
+    );
+    // 2026-04-15 is a Wednesday; ISO week Mon 13 - Sun 19
+    expect(screen.getByTestId("flight-schedule-note").textContent).toContain("13.04.2026");
+    expect(screen.getByTestId("flight-schedule-note").textContent).toContain("19.04.2026");
+  });
+
+  it("renders scheduled departure/arrival times and duration", () => {
+    render(
+      <FlightSchedule flight={makeFlight({ daysOfWeek: { current: "1000010", flight: "1111111" } })} />,
+    );
+    // Note: accordion open by default; times visible in content
+    // departure time: the local ISO string's time component
+    expect(screen.getByText("10:00")).toBeTruthy();
+    expect(screen.getByText("12:30")).toBeTruthy();
+    expect(screen.getByText("2h 30m")).toBeTruthy();
+  });
+});
+```
+
+- [ ] **Step 2: Verify fail**
+
+Run: `pnpm vitest run src/features/online-board/components/FlightSchedule/FlightSchedule.test.tsx`
+
+Expected: FAIL.
+
+- [ ] **Step 3: Create `FlightSchedule.scss`**
+
+```scss
+.flight-schedule {
+  background: #fff;
+  border-radius: 8px;
+  padding: 16px 24px;
+  margin-top: 16px;
+
+  .p-accordion-content {
+    padding: 12px 0;
+  }
+
+  &__row {
+    display: flex;
+    justify-content: space-between;
+    padding: 4px 0;
+  }
+
+  &__label { color: #666; }
+  &__value { font-weight: 500; }
+
+  &__days-section {
+    margin-top: 16px;
+    padding-top: 16px;
+    border-top: 1px solid #eee;
+  }
+
+  &__section-title {
+    font-size: 12px;
+    color: #666;
+    text-transform: uppercase;
+    margin-bottom: 8px;
+  }
+
+  &__note {
+    margin-top: 12px;
+    font-size: 12px;
+    color: #666;
+    font-style: italic;
+  }
+}
+
+.days-of-week-strip {
+  display: flex;
+  gap: 8px;
+  flex-wrap: wrap;
+
+  .day {
+    padding: 8px 12px;
+    border-radius: 6px;
+    background: #e6f1fb;
+    font-size: 14px;
+    font-weight: 500;
+    color: #1a3a5c;
+
+    &--inactive {
+      background: #f6f6f6;
+      color: rgba(102, 102, 102, 0.5);
+    }
+  }
+}
+```
+
+- [ ] **Step 4: Create `FlightSchedule.tsx`**
+
+```tsx
+import type { FC } from "react";
+import { Accordion, AccordionTab } from "primereact/accordion";
+import { useTranslation } from "@/i18n/provider.js";
+import type { ISimpleFlight } from "../../types.js";
+import { DaysOfWeekStrip } from "./DaysOfWeekStrip.js";
+import { getWeekDateRange } from "./weekDateRange.js";
+import "./FlightSchedule.scss";
+
+export interface FlightScheduleProps {
+  flight: ISimpleFlight;
+}
+
+function formatLocalTime(iso: string | undefined): string {
+  if (!iso) return "";
+  // If it's already "HH:mm" (no date), return as-is
+  if (/^\d{2}:\d{2}$/.test(iso)) return iso;
+  // Otherwise try to extract time part from ISO: "2026-04-15T10:00:00" → "10:00"
+  const match = /T(\d{2}:\d{2})/.exec(iso);
+  return match ? match[1]! : iso;
+}
+
+export const FlightSchedule: FC<FlightScheduleProps> = ({ flight }) => {
+  const { t } = useTranslation();
+
+  const firstLeg = flight.routeType === "Direct" ? flight.leg : flight.legs[0];
+  const lastLeg = flight.routeType === "Direct" ? flight.leg : flight.legs[flight.legs.length - 1];
+
+  if (!firstLeg?.daysOfWeek?.flight) return null;
+  if (!lastLeg) return null;
+
+  const depLocal = firstLeg.departure.times.scheduledDeparture.local;
+  const arrLocal = lastLeg.arrival.times.scheduledArrival.local;
+
+  const { start, end } = getWeekDateRange(depLocal);
+  const noteTemplate = t("SHARED.NOTE-TIME-SCHEDULE");
+  const note = noteTemplate.replace("{START_DATE}", start).replace("{END_DATE}", end);
+
+  return (
+    <section className="flight-schedule" data-testid="flight-schedule">
+      <Accordion multiple={false} activeIndex={0}>
+        <AccordionTab header={t("SHARED.SCHEDULE-FLIGHT")}>
+          <div className="flight-schedule__row">
+            <span className="flight-schedule__label">{t("SHARED.DEPARTURE-SCHEDULED")}</span>
+            <span className="flight-schedule__value">{formatLocalTime(depLocal)}</span>
+          </div>
+          <div className="flight-schedule__row">
+            <span className="flight-schedule__label">{t("SHARED.ARRIVAL-SCHEDULED")}</span>
+            <span className="flight-schedule__value">{formatLocalTime(arrLocal)}</span>
+          </div>
+          <div className="flight-schedule__row">
+            <span className="flight-schedule__label">{t("SHARED.PATH-TIME")}</span>
+            <span className="flight-schedule__value">{flight.flyingTime}</span>
+          </div>
+        </AccordionTab>
+      </Accordion>
+
+      <div className="flight-schedule__days-section">
+        <div className="flight-schedule__section-title">
+          {t("SHARED.DAYS-EXECUTE-FLIGHT")}
+        </div>
+        <DaysOfWeekStrip flightBitString={firstLeg.daysOfWeek.flight} />
+        <div className="flight-schedule__note" data-testid="flight-schedule-note">{note}</div>
+      </div>
+    </section>
+  );
+};
+```
+
+- [ ] **Step 5: Create `index.ts`**
+
+```typescript
+export { FlightSchedule } from "./FlightSchedule.js";
+export type { FlightScheduleProps } from "./FlightSchedule.js";
+```
+
+- [ ] **Step 6: Verify pass**
+
+Run: `pnpm vitest run src/features/online-board/components/FlightSchedule/FlightSchedule.test.tsx`
+
+Expected: 6 tests pass.
+
+- [ ] **Step 7: Commit**
+
+```bash
+git add src/features/online-board/components/FlightSchedule/
+git commit -m "Add FlightSchedule accordion with days-of-week strip"
+```
+
+---
+
+### Task 5: `DetailsBackButton` Component
+
+**Files:**
+- Create: `src/features/online-board/components/DetailsBackButton/DetailsBackButton.tsx`
+- Create: `src/features/online-board/components/DetailsBackButton/DetailsBackButton.scss`
+- Create: `src/features/online-board/components/DetailsBackButton/DetailsBackButton.test.tsx`
+- Create: `src/features/online-board/components/DetailsBackButton/index.ts`
+
+- [ ] **Step 1: Write failing test**
+
+```tsx
+// @vitest-environment jsdom
+import { describe, it, expect, vi } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { DetailsBackButton } from "./DetailsBackButton.js";
+
+vi.mock("@/i18n/provider.js", () => ({
+  useTranslation: () => ({ t: (k: string) => k }),
+}));
+
+vi.mock("@modern-js/runtime/router", () => ({
+  Link: ({ children, to, ...props }: { children: React.ReactNode; to: string; [k: string]: unknown }) => (
+    <a href={to} {...props}>{children}</a>
+  ),
+}));
+
+describe("DetailsBackButton", () => {
+  it("has data-testid=details-back-button", () => {
+    render(<DetailsBackButton locale="ru" />);
+    expect(screen.getByTestId("details-back-button")).toBeTruthy();
+  });
+
+  it("links to /{locale}/onlineboard", () => {
+    render(<DetailsBackButton locale="ru" />);
+    const a = screen.getByTestId("details-back-button") as HTMLAnchorElement;
+    expect(a.getAttribute("href")).toBe("/ru/onlineboard");
+  });
+
+  it("uses the provided locale in the link", () => {
+    render(<DetailsBackButton locale="en" />);
+    const a = screen.getByTestId("details-back-button") as HTMLAnchorElement;
+    expect(a.getAttribute("href")).toBe("/en/onlineboard");
+  });
+
+  it("renders the BACK-BOARD label", () => {
+    render(<DetailsBackButton locale="ru" />);
+    expect(screen.getByText("SHARED.BACK-BOARD")).toBeTruthy();
+  });
+});
+```
+
+- [ ] **Step 2: Verify fail**
+
+Run: `pnpm vitest run src/features/online-board/components/DetailsBackButton/DetailsBackButton.test.tsx`
+
+Expected: FAIL.
+
+- [ ] **Step 3: Create `DetailsBackButton.scss`**
+
+```scss
+.details-back-button {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  padding: 8px 16px;
+  background: #e3f0ff;
+  color: #1a3a5c;
+  border-radius: 6px;
+  text-decoration: none;
+  font-size: 14px;
+  font-family: inherit;
+  cursor: pointer;
+
+  &:hover {
+    background: #c7dff5;
+  }
+
+  &__arrow {
+    display: inline-block;
+    font-size: 16px;
+  }
+}
+```
+
+- [ ] **Step 4: Create `DetailsBackButton.tsx`**
+
+```tsx
+import type { FC } from "react";
+import { Link } from "@modern-js/runtime/router";
+import { useTranslation } from "@/i18n/provider.js";
+import "./DetailsBackButton.scss";
+
+export interface DetailsBackButtonProps {
+  locale: string;
+}
+
+export const DetailsBackButton: FC<DetailsBackButtonProps> = ({ locale }) => {
+  const { t } = useTranslation();
+  return (
+    <Link
+      to={`/${locale}/onlineboard`}
+      className="details-back-button"
+      data-testid="details-back-button"
+    >
+      <span className="details-back-button__arrow" aria-hidden="true">{"\u2190"}</span>
+      <span>{t("SHARED.BACK-BOARD")}</span>
+    </Link>
+  );
+};
+```
+
+- [ ] **Step 5: Create `index.ts`**
+
+```typescript
+export { DetailsBackButton } from "./DetailsBackButton.js";
+export type { DetailsBackButtonProps } from "./DetailsBackButton.js";
+```
+
+- [ ] **Step 6: Verify pass**
+
+Run: `pnpm vitest run src/features/online-board/components/DetailsBackButton/DetailsBackButton.test.tsx`
+
+Expected: 4 tests pass.
+
+- [ ] **Step 7: Commit**
+
+```bash
+git add src/features/online-board/components/DetailsBackButton/
+git commit -m "Add DetailsBackButton component for header navigation"
+```
+
+---
+
+### Task 6: Wire Both into `OnlineBoardDetailsPage`
+
+**Files:**
+- Modify: `src/features/online-board/components/OnlineBoardDetailsPage.tsx`
+- Modify: `src/features/online-board/components/OnlineBoardDetailsPage.test.tsx`
+
+- [ ] **Step 1: Add integration tests**
+
+Append to the outer describe block in `OnlineBoardDetailsPage.test.tsx`:
+
+```tsx
+describe("back button integration", () => {
+  it("renders DetailsBackButton in headerLeft", () => {
+    mockState = { flight: mockFlight, allFlights: [mockFlight], daysOfFlight: ["20260416"], loading: false, error: null };
+    render(<OnlineBoardDetailsPage flightId={mockFlightId} locale="ru" canonicalOrigin="https://example.com" />);
+    expect(screen.getByTestId("details-back-button")).toBeTruthy();
+  });
+});
+
+describe("flight schedule integration", () => {
+  it("renders FlightSchedule when firstLeg.daysOfWeek is present", () => {
+    const flightWithDaysOfWeek = {
+      ...mockFlight,
+      leg: {
+        ...mockFlight.leg,
+        daysOfWeek: { current: "1000010", flight: "1111111" },
+      },
+    };
+    mockState = { flight: flightWithDaysOfWeek, allFlights: [flightWithDaysOfWeek], daysOfFlight: ["20260416"], loading: false, error: null };
+    render(<OnlineBoardDetailsPage flightId={mockFlightId} locale="ru" canonicalOrigin="https://example.com" />);
+    expect(screen.getByTestId("flight-schedule")).toBeTruthy();
+  });
+
+  it("does not render FlightSchedule when daysOfWeek is absent", () => {
+    mockState = { flight: mockFlight, allFlights: [mockFlight], daysOfFlight: ["20260416"], loading: false, error: null };
+    render(<OnlineBoardDetailsPage flightId={mockFlightId} locale="ru" canonicalOrigin="https://example.com" />);
+    expect(screen.queryByTestId("flight-schedule")).toBeNull();
+  });
+});
+```
+
+- [ ] **Step 2: Run tests — expect failure**
+
+Run: `pnpm vitest run src/features/online-board/components/OnlineBoardDetailsPage.test.tsx`
+
+Expected: the 3 new tests fail (testids not present).
+
+- [ ] **Step 3: Update imports in `OnlineBoardDetailsPage.tsx`**
+
+Add near other component imports:
+
+```tsx
+import { DetailsBackButton } from "./DetailsBackButton/index.js";
+import { FlightSchedule } from "./FlightSchedule/index.js";
+```
+
+- [ ] **Step 4: Swap PageTabs for DetailsBackButton**
+
+In `OnlineBoardDetailsPage.tsx`, find `const commonLayoutProps` (around line 194):
+
+```tsx
+  const commonLayoutProps = {
+    headerLeft: <PageTabs viewType="onlineboard" />,
+    breadcrumbs: [
+      { label: t("BREADCRUMBS.ONLINEBOARD"), url: onlineboardHref },
+    ],
+  };
+```
+
+Change to:
+
+```tsx
+  const commonLayoutProps = {
+    headerLeft: <DetailsBackButton locale={locale} />,
+    breadcrumbs: [
+      { label: t("BREADCRUMBS.ONLINEBOARD"), url: onlineboardHref },
+    ],
+  };
+```
+
+Also find the main happy-path return's `<PageLayout>` opening:
+
+```tsx
+      <PageLayout
+        headerLeft={<PageTabs viewType="onlineboard" />}
+        title={<h1 className="flight-details__flight-number">{flightNumber}</h1>}
+```
+
+Change to:
+
+```tsx
+      <PageLayout
+        headerLeft={<DetailsBackButton locale={locale} />}
+        title={<h1 className="flight-details__flight-number">{flightNumber}</h1>}
+```
+
+The `PageTabs` import becomes unused — remove it from the import list at the top of the file.
+
+- [ ] **Step 5: Insert `<FlightSchedule />` after the flight legs**
+
+In the main return, find the closing tag after the flying-time div (after `<FlightLegs legs={legs} />` + the flying-time div, just before closing `</div>` of `.flight-details`):
+
+```tsx
+          {/* Flying time */}
+          <div className="flight-details__flying-time" data-testid="flying-time">
+            Total flying time: {displayFlight.flyingTime}
+          </div>
+        </div>
+```
+
+Insert `<FlightSchedule flight={displayFlight} />` after the flying-time div (before the `</div>` closing `.flight-details`):
+
+```tsx
+          {/* Flying time */}
+          <div className="flight-details__flying-time" data-testid="flying-time">
+            Total flying time: {displayFlight.flyingTime}
+          </div>
+
+          <FlightSchedule flight={displayFlight} />
+        </div>
+```
+
+- [ ] **Step 6: Run tests — expect pass**
+
+Run: `pnpm vitest run src/features/online-board/components/OnlineBoardDetailsPage.test.tsx`
+
+Expected: all tests pass, including the 3 new integration tests.
+
+- [ ] **Step 7: Full suite + typecheck**
+
+Run: `pnpm test`
+Run: `pnpm typecheck`
+
+Expected: no new failures, no new type errors. If any integration tests elsewhere (e.g., `tests/integration/online-board/*.test.tsx`) reference `PageTabs` via the details page, they may need the `DetailsBackButton` testid instead of the `onlineboard-tab` testid — fix those test assertions minimally.
+
+- [ ] **Step 8: Commit**
+
+```bash
+git add src/features/online-board/components/OnlineBoardDetailsPage.tsx src/features/online-board/components/OnlineBoardDetailsPage.test.tsx
+git commit -m "Wire DetailsBackButton and FlightSchedule into OnlineBoardDetailsPage"
+```
+
+---
+
+### Task 7: Manual Browser Verification
+
+**Files:** None — observational.
+
+- [ ] **Step 1: Ensure dev:full is running**
+
+Run `pnpm dev:full`. Verify `/api/appSettings` returns 200.
+
+- [ ] **Step 2: Run the verification script**
+
+```bash
+cat << 'SCRIPT' | npx tsx --input-type=module -
+import { chromium } from "@playwright/test";
+import { mockAngularAPIs } from "./tests/e2e-angular/support/angular-api-mock.js";
+
+const browser = await chromium.launch({ headless: true });
+const ctx = await browser.newContext({ viewport: { width: 1440, height: 900 } });
+const page = await ctx.newPage();
+await mockAngularAPIs(page);
+
+const depUtc = new Date(Date.now() + 24 * 60 * 60 * 1000).toISOString();
+await page.route("**/onlineboard/details*", (route) => {
+  route.fulfill({
+    status: 200, contentType: "application/json",
+    body: JSON.stringify({
+      data: {
+        partners: [],
+        routes: [{
+          id: "SU0022-X", routeType: "Direct", flyingTime: "1h 30m", status: "Scheduled",
+          flightId: { carrier: "SU", flightNumber: "0022", suffix: "", date: "20260418", dateLT: "20260418" },
+          operatingBy: { carrier: "SU", flightNumber: "0022" },
+          leg: {
+            index: 0, flyingTime: "1h 30m", status: "Scheduled", updated: "2026-04-17T10:00:00Z", dayChange: 0,
+            flags: { checkinAvailable: false, returnToAirport: false, routeChanged: false },
+            operatingBy: { carrier: "SU", flightNumber: "0022" },
+            daysOfWeek: { current: "1000010", flight: "1111100" },
+            departure: {
+              scheduled: { airport: "SVO", airportCode: "SVO", city: "MOW", cityCode: "MOW", countryCode: "RU" },
+              latest: { airport: "SVO", airportCode: "SVO", city: "MOW", cityCode: "MOW", countryCode: "RU" },
+              dispatch: "", gate: "", terminal: "", checkingStatus: "Scheduled", parkingStand: "",
+              times: { scheduledDeparture: { dayChange: { value: 0, title: "" }, local: "2026-04-18T10:00:00", localTime: "10:00", tzOffset: 3, utc: depUtc } },
+            },
+            arrival: {
+              scheduled: { airport: "LED", airportCode: "LED", city: "SPB", cityCode: "LED", countryCode: "RU" },
+              latest: { airport: "LED", airportCode: "LED", city: "SPB", cityCode: "LED", countryCode: "RU" },
+              dispatch: "", gate: "", terminal: "",
+              times: { scheduledArrival: { dayChange: { value: 0, title: "" }, local: "2026-04-18T12:30:00", localTime: "12:30", tzOffset: 3, utc: "" } },
+            },
+            equipment: {},
+          },
+        }],
+        daysOfFlight: ["20260418"],
+      },
+    }),
+  });
+});
+
+await page.goto("http://localhost:8080/ru/onlineboard/SU0022-20260418", { waitUntil: "networkidle" });
+await page.waitForTimeout(3000);
+
+const backBtn = await page.locator('[data-testid="details-back-button"]').count();
+const schedule = await page.locator('[data-testid="flight-schedule"]').count();
+const dayBoxes = await page.locator('[data-testid^="day-of-week-"]').count();
+const noteText = await page.locator('[data-testid="flight-schedule-note"]').textContent().catch(() => "");
+
+console.log("backBtn:", backBtn);
+console.log("schedule:", schedule);
+console.log("dayBoxes:", dayBoxes);
+console.log("note:", noteText);
+
+await page.screenshot({ path: "/tmp/b6-verify.png", fullPage: true });
+
+await browser.close();
+SCRIPT
+```
+
+Expected: `backBtn: 1, schedule: 1, dayBoxes: 7, note: "Valid from 13.04.2026 to 19.04.2026"` (or Russian equivalent depending on the real i18n key value).
+
+- [ ] **Step 3: No commit — observational**