feat(calendar): read-only ICS feeds for tenant and staff

GET /v1/public/calendar/{token} serves an RFC 5545 calendar under a
token-as-secret URL (private Google/Outlook link model). Staff feeds
contain only that member's bookings; the tenant feed tags each event
with the staff member. Window is -30d to +180d; cancelled bookings map
to STATUS:CANCELLED, waitlisted/pending to TENTATIVE + TRANSPARENT.
Summaries resolve service or class-session titles, descriptions carry
localized contact labels, locations resolve to names.

Feed tokens live on tenants/staff (migration 00015) and are managed via
GET /v1/calendar/feed plus POST /v1/calendar/feed/rotate — rotating a
scope invalidates the old URL. ICS rendering is hand-rolled: TEXT
escaping, CRLF, 75-octet folding on rune boundaries.

Settings gains a "Kalendář (ICS)" card with copyable URLs and two-step
rotation per scope; demo mode points at the real seeded tokens.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/calendar/service_test.go

@@ -0,0 +1,249 @@
+package calendar
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"bookra/apps/backend/internal/db"
+	"bookra/apps/backend/internal/domain"
+)
+
+const (
+	demoTenantID   = "5d6b3551-0a3e-4b86-bdf0-e9df20a47148"
+	demoStaffID    = "6936c444-c7d0-4a7d-b596-a9b72d2f4fc0"
+	demoServiceID  = "d5d76a61-3d49-467c-8dd4-bf61ee754e39"
+	demoLocationID = "659f1cc0-a850-46d6-b3b8-cb15d55d8daf"
+	demoSessionID  = "4bf74c12-44dd-45ca-86bb-b104f16f2435"
+)
+
+var owner = domain.Principal{Subject: "demo-owner", Email: "[email protected]", Role: "owner"}
+
+func seedAppointment(t *testing.T, repo *db.MemoryRepository, staffID *string, status string) db.CreatedBooking {
+	t.Helper()
+	startsAt := time.Now().UTC().Add(24 * time.Hour).Truncate(time.Minute)
+	created, err := repo.CreateBooking(context.Background(), db.CreateBookingParams{
+		TenantID:      demoTenantID,
+		ServiceID:     &[]string{demoServiceID}[0],
+		StaffID:       staffID,
+		LocationID:    &[]string{demoLocationID}[0],
+		BookingMode:   "appointment",
+		CustomerName:  "Feed Customer",
+		CustomerEmail: "[email protected]",
+		CustomerPhone: "+420111222333",
+		StartsAt:      startsAt,
+		EndsAt:        startsAt.Add(time.Hour),
+		Status:        status,
+		Reference:     "BK-FEED-" + status,
+		ManageToken:   "feed-token-" + status,
+	})
+	if err != nil {
+		t.Fatalf("seed booking: %v", err)
+	}
+	return created
+}
+
+func TestRenderCalendarEscapesAndFolds(t *testing.T) {
+	body := RenderCalendar("Studio, Atelier; test", "Europe/Prague", []Event{{
+		UID:         "abc@bookra",
+		StartsAt:    time.Date(2026, 9, 20, 7, 0, 0, 0, time.UTC),
+		EndsAt:      time.Date(2026, 9, 20, 8, 0, 0, 0, time.UTC),
+		Summary:     "Massage; comma, back\\slash\nnewline",
+		Description: "Line one\nLine two",
+		Status:      "cancelled",
+	}})
+
+	for _, want := range []string{
+		"BEGIN:VCALENDAR", "END:VCALENDAR", "BEGIN:VEVENT", "END:VEVENT",
+		"DTSTART:20260920T070000Z", "DTEND:20260920T080000Z",
+		"SUMMARY:Massage\\; comma\\, back\\\\slash\\nnewline",
+		"DESCRIPTION:Line one\\nLine two",
+		"STATUS:CANCELLED",
+		"X-WR-CALNAME:Studio\\, Atelier\\; test",
+		"X-WR-TIMEZONE:Europe/Prague",
+	} {
+		if !strings.Contains(body, want) {
+			t.Fatalf("expected %q in feed:\n%s", want, body)
+		}
+	}
+	if strings.Contains(strings.ReplaceAll(body, "\r\n", ""), "\n") || !strings.Contains(body, "\r\n") {
+		t.Fatalf("expected CRLF line endings only")
+	}
+	for _, line := range strings.Split(strings.TrimRight(body, "\r\n"), "\r\n") {
+		if len(line) > 75 {
+			t.Fatalf("line exceeds 75 octets (%d): %q", len(line), line)
+		}
+	}
+}
+
+func TestRenderCalendarFoldsLongLines(t *testing.T) {
+	long := strings.Repeat("x", 200)
+	body := RenderCalendar("test", "", []Event{{
+		UID: "a@b", StartsAt: time.Now(), EndsAt: time.Now(), Summary: long, Status: "confirmed",
+	}})
+	for _, line := range strings.Split(strings.TrimRight(body, "\r\n"), "\r\n") {
+		if len(line) > 75 {
+			t.Fatalf("line exceeds 75 octets (%d): %q", len(line), line)
+		}
+	}
+	if !strings.Contains(body, "\r\n ") {
+		t.Fatalf("expected folded continuation lines")
+	}
+}
+
+func TestFeedInfoReturnsTokens(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+
+	info, err := svc.FeedInfo(context.Background(), owner)
+	if err != nil {
+		t.Fatalf("feed info: %v", err)
+	}
+	if info.Tenant.Token == "" || !strings.HasPrefix(info.Tenant.FeedPath, "/v1/public/calendar/") {
+		t.Fatalf("bad tenant entry: %+v", info.Tenant)
+	}
+	if len(info.Staff) != 1 || info.Staff[0].StaffID != demoStaffID || info.Staff[0].Token == "" {
+		t.Fatalf("bad staff entries: %+v", info.Staff)
+	}
+}
+
+func TestRenderFeedTenantIncludesAllBookings(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+	ctx := context.Background()
+
+	seedAppointment(t, repo, &[]string{demoStaffID}[0], "confirmed")
+	seedAppointment(t, repo, nil, "cancelled")
+
+	ics, err := svc.RenderFeed(ctx, "demo-tenant-feed-token")
+	if err != nil {
+		t.Fatalf("render feed: %v", err)
+	}
+	if count := strings.Count(ics, "BEGIN:VEVENT"); count != 2 {
+		t.Fatalf("expected 2 events, got %d", count)
+	}
+	if !strings.Contains(ics, "Signature treatment · Feed Customer · Demo Stylist") {
+		t.Fatalf("expected service+customer+staff summary:\n%s", ics)
+	}
+	if !strings.Contains(ics, "STATUS:CANCELLED") {
+		t.Fatalf("expected cancelled event status:\n%s", ics)
+	}
+	if !strings.Contains(ics, "Telefon: +420111222333") {
+		t.Fatalf("expected czech description labels:\n%s", ics)
+	}
+	if !strings.Contains(ics, "LOCATION:Main Studio") {
+		t.Fatalf("expected location:\n%s", ics)
+	}
+}
+
+func TestRenderFeedStaffFilters(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+	ctx := context.Background()
+
+	seedAppointment(t, repo, &[]string{demoStaffID}[0], "confirmed")
+	seedAppointment(t, repo, nil, "confirmed") // unassigned — not in staff feed
+	seedAppointment(t, repo, &[]string{"other-staff"}[0], "confirmed")
+
+	ics, err := svc.RenderFeed(ctx, "demo-staff-feed-token")
+	if err != nil {
+		t.Fatalf("render feed: %v", err)
+	}
+	if count := strings.Count(ics, "BEGIN:VEVENT"); count != 1 {
+		t.Fatalf("expected 1 event in staff feed, got %d", count)
+	}
+	if !strings.Contains(ics, "Studio Atelier · Demo Stylist") {
+		t.Fatalf("expected staff feed name:\n%s", ics)
+	}
+}
+
+func TestRenderFeedUnknownToken(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+
+	if _, err := svc.RenderFeed(context.Background(), "nonsense"); err != ErrFeedNotFound {
+		t.Fatalf("expected ErrFeedNotFound, got %v", err)
+	}
+}
+
+func TestRotateTokenInvalidatesOldFeed(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+	ctx := context.Background()
+
+	newToken, err := svc.RotateToken(ctx, owner, "tenant", "")
+	if err != nil {
+		t.Fatalf("rotate tenant token: %v", err)
+	}
+	if newToken == "" || newToken == "demo-tenant-feed-token" {
+		t.Fatalf("expected fresh token, got %q", newToken)
+	}
+	if _, err := svc.RenderFeed(ctx, "demo-tenant-feed-token"); err != ErrFeedNotFound {
+		t.Fatalf("old token should 404, got %v", err)
+	}
+	if _, err := svc.RenderFeed(ctx, newToken); err != nil {
+		t.Fatalf("new token should render: %v", err)
+	}
+}
+
+func TestRotateStaffTokenAndScopeValidation(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+	ctx := context.Background()
+
+	newToken, err := svc.RotateToken(ctx, owner, "staff", demoStaffID)
+	if err != nil {
+		t.Fatalf("rotate staff token: %v", err)
+	}
+	if _, err := svc.RenderFeed(ctx, newToken); err != nil {
+		t.Fatalf("new staff token should render: %v", err)
+	}
+
+	if _, err := svc.RotateToken(ctx, owner, "staff", "not-our-staff"); err != ErrInvalidScope {
+		t.Fatalf("expected ErrInvalidScope for foreign staff, got %v", err)
+	}
+	if _, err := svc.RotateToken(ctx, owner, "bogus", ""); err != ErrInvalidScope {
+		t.Fatalf("expected ErrInvalidScope for bad scope, got %v", err)
+	}
+	if _, err := svc.RotateToken(ctx, domain.Principal{Subject: "stranger", Role: "owner"}, "tenant", ""); err != ErrTenantMembership {
+		t.Fatalf("expected ErrTenantMembership, got %v", err)
+	}
+}
+
+func TestRenderFeedWaitlistedIsTransparent(t *testing.T) {
+	repo := db.NewMemoryRepository()
+	svc := NewService(repo)
+	ctx := context.Background()
+
+	session, err := repo.GetClassSessionByID(ctx, demoSessionID)
+	if err != nil {
+		t.Fatalf("get session: %v", err)
+	}
+	_, err = repo.CreateBooking(ctx, db.CreateBookingParams{
+		TenantID:       demoTenantID,
+		ClassSessionID: &[]string{demoSessionID}[0],
+		BookingMode:    "class",
+		CustomerName:   "Queued Person",
+		CustomerEmail:  "[email protected]",
+		StartsAt:       session.StartsAt,
+		EndsAt:         session.EndsAt,
+		Status:         "waitlisted",
+		Reference:      "BK-WAIT",
+		ManageToken:    "wait-token",
+	})
+	if err != nil {
+		t.Fatalf("seed waitlisted: %v", err)
+	}
+
+	ics, err := svc.RenderFeed(ctx, "demo-tenant-feed-token")
+	if err != nil {
+		t.Fatalf("render feed: %v", err)
+	}
+	if !strings.Contains(ics, "STATUS:TENTATIVE") || !strings.Contains(ics, "TRANSP:TRANSPARENT") {
+		t.Fatalf("expected tentative+transparent waitlist event:\n%s", ics)
+	}
+	if !strings.Contains(ics, "(čekací listina)") {
+		t.Fatalf("expected czech waitlist marker:\n%s", ics)
+	}
+}