fix(pdf): print a day in the order the plan shows it

The export ordered each day by itself, on day_plan_position — one global
number per booking, seeded automatically from the place count of whichever
day happened to render first. On any other day of a span it therefore pointed
at the wrong slot, and where it was still null the export fell back to the
order the API returned rows in, which is reservation_time ASC with nulls
first.

That is why the same trip printed correctly some of the time and swapped two
bookings the rest of it, and why the reporter's workaround worked: adding a
place and removing it again reseeded the position from the day they were
looking at.

The plan has never used that column. It picks transports per day, gives each
one the time that day shows, inserts them among the places and re-sorts the
whole day by the clock — and none of that was reachable from here, because
this file had its own copy of the ordering with subtly different rules.

So the copy is gone and the export goes through utils/dayMerge, the same
functions the plan uses. Two differences fall out of that, both of them the
plan's existing behaviour: a booking attached to a place is no longer printed
twice, and a multi-leg journey prints one row per leg at each leg's own time
rather than one row carrying every leg as a subtitle. The per-segment booking
code #1943 added is read back from the booking, since the leg object does not
carry it.

Closes #1978

client/src/components/PDF/TripPDF.test.ts

@@ -4,6 +4,7 @@ import { http, HttpResponse } from 'msw'
 import { downloadTripPDF } from './TripPDF'
 import { server } from '../../../tests/helpers/msw/server'
 import { clearExchangeRateCache } from '../../hooks/useExchangeRates'
+import { getMergedItems, getTransportForDay } from '../../utils/dayMerge'
 
 // ── Helpers ───────────────────────────────────────────────────────────────────
 
@@ -1096,3 +1097,114 @@ describe('page breaks between days (#1292)', () => {
     expect(html.slice(at - 10, at)).toContain('.pdf-flow ')
   })
 })
+
+/**
+ * The order a day prints in (#1978).
+ *
+ * The export used to order a day by itself, on `day_plan_position` — one global
+ * number per booking, auto-seeded from whichever day happened to render first.
+ * On any other day of a span it therefore pointed at the wrong slot, and where
+ * it was still null the export fell back to the order the API returned rows in.
+ * That is why the same trip printed correctly some of the time and swapped two
+ * bookings the rest of it, and why adding a place and removing it again "fixed"
+ * it: the reseed happened to land on the day being looked at.
+ *
+ * It now goes through utils/dayMerge, the same functions the day plan uses, so
+ * the two cannot disagree. These cases are written from the plan's rules rather
+ * than from the old implementation's.
+ */
+describe('a printed day follows the plan (#1978)', () => {
+  const d1 = { id: 21, day_number: 1, title: 'Day One', date: '2025-06-01' } as any
+  const d2 = { id: 22, day_number: 2, title: 'Day Two', date: '2025-06-02' } as any
+  const srcdoc = () => getIframe()!.srcdoc
+
+  /** Where each needle first appears, so order can be asserted without parsing. */
+  const positions = (html: string, needles: string[]) => needles.map(n => html.indexOf(n))
+
+  it('orders the day by the clock, not by the order the API sent rows in', async () => {
+    await downloadTripPDF({
+      ...minimalArgs,
+      trip: { id: 21, title: 'Order Trip', description: null, cover_image: null } as any,
+      days: [d1],
+      // As the API returns them: reservation_time ASC with nulls first.
+      reservations: [
+        { id: 1, title: 'Untimed Transfer', type: 'transfer', day_id: 21, reservation_time: null },
+        { id: 2, title: 'Evening Train', type: 'train', day_id: 21, reservation_time: '2025-06-01T19:30' },
+        { id: 3, title: 'Morning Flight', type: 'flight', day_id: 21, reservation_time: '2025-06-01T07:15' },
+      ],
+    })
+    const [morning, evening] = positions(srcdoc(), ['Morning Flight', 'Evening Train'])
+    expect(morning).toBeGreaterThan(-1)
+    expect(evening).toBeGreaterThan(-1)
+    expect(morning).toBeLessThan(evening)
+  })
+
+  /*
+   * The reported shape: a booking on the last day of a span whose global
+   * position was seeded from a busier earlier day, which sank it below
+   * everything on the day it actually belongs to.
+   */
+  it('ignores a global position seeded from another day', async () => {
+    await downloadTripPDF({
+      ...minimalArgs,
+      trip: { id: 22, title: 'Span Trip', description: null, cover_image: null } as any,
+      days: [d1, d2],
+      reservations: [
+        {
+          id: 4, title: 'Car Return', type: 'car', day_id: 21, end_day_id: 22,
+          reservation_time: '2025-06-01T10:00', reservation_end_time: '2025-06-02T09:00',
+          // Seeded from day one, where five places had already been placed.
+          day_plan_position: 5,
+        },
+        { id: 5, title: 'Late Flight', type: 'flight', day_id: 22, reservation_time: '2025-06-02T18:00' },
+      ],
+    })
+    const html = srcdoc()
+    // On day two the 09:00 return comes before the 18:00 flight, whatever the
+    // stale global position says.
+    const [ret, flight] = positions(html, ['Car Return', 'Late Flight'])
+    expect(ret).toBeGreaterThan(-1)
+    expect(flight).toBeGreaterThan(-1)
+    expect(ret).toBeLessThan(flight)
+  })
+
+  /*
+   * The strongest form of the same claim: whatever the plan would show, the
+   * print shows, in that order. Asserted against getMergedItems itself rather
+   * than against a hand-written expectation, so the two cannot drift apart
+   * again without this failing.
+   */
+  it('prints a mixed day in exactly the order the plan merges it', async () => {
+    const reservations = [
+      { id: 8, title: 'Untimed Transfer', type: 'transfer', day_id: 21, reservation_time: null },
+      { id: 9, title: 'Evening Train', type: 'train', day_id: 21, reservation_time: '2025-06-01T19:30' },
+      { id: 10, title: 'Morning Flight', type: 'flight', day_id: 21, reservation_time: '2025-06-01T07:15' },
+    ]
+    const dayAssignments = [
+      { id: 100, day_id: 21, order_index: 0, place: { id: 1, name: 'Museum', place_time: '11:00' } },
+      { id: 101, day_id: 21, order_index: 1, place: { id: 2, name: 'Market', place_time: '16:00' } },
+    ]
+
+    await downloadTripPDF({
+      ...minimalArgs,
+      trip: { id: 24, title: 'Mixed Trip', description: null, cover_image: null } as any,
+      days: [d1],
+      assignments: { '21': dayAssignments } as any,
+      reservations,
+    })
+    const html = srcdoc()
+
+    const expected = getMergedItems({
+      dayAssignments,
+      dayNotes: [],
+      dayTransports: getTransportForDay({
+        reservations, dayId: 21, dayAssignmentIds: dayAssignments.map(a => a.id), days: [d1],
+      }),
+      dayId: 21,
+    }).map(item => (item.type === 'place' ? item.data.place.name : item.data.title))
+
+    const seen = expected.map(name => html.indexOf(name))
+    for (const at of seen) expect(at).toBeGreaterThan(-1)
+    expect(seen).toEqual([...seen].sort((a, b) => a - b))
+  })
+})