Add Coach mode C3: game line-up, the last of the six coach screens

New models (events/models.py): Lineup (one per event), LineupUnit (Line 1,
Defence pair 1, ... -- coach-entered labels, no fixed sport structure since
neither Club nor Team carries one), LineupSlot (one position, optionally
filled by a member). events/services/lineup.py's publish_lineup is the
reason Attendance.AttendanceStatus.SELECTED/NOT_SELECTED existed at all --
publishing flips every slotted member to SELECTED and every other available
(non-out, non-silent) roster member to NOT_SELECTED, then notifies only the
selected players.

Placement is a native <select> per slot, batch-saved with one "Save
line-up" submit, not the design mock's drag-and-drop -- this codebase has
no established htmx interaction pattern yet (htmx.js is loaded but nothing
uses it) to build a live per-tap version on, and a reliable plain form beats
a first, unproven real-time interaction for an already-large screen.
place_member handles "swap" semantics for it: placing a member vacates any
other slot of theirs in the same lineup, bumping whoever was already in the
target slot back to the available pool.

Wires the missing pieces from C1's own docstring: the "needs you" line-up-
not-published row and the tonight card's "Line-up" button, both deferred
in that stage specifically because this model didn't exist yet.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

events/tests.py

@@ -19,7 +19,7 @@ from notifications.models import Notification
 from teams.models import Position, RefereeLevel, RefereeProfile, Team, TeamMembership
 
 from .admin import EventAdminForm
-from .models import Attendance, Competition, Event, EventReferee, EventSeries, Location, Opponent
+from .models import Attendance, Competition, Event, EventReferee, EventSeries, Lineup, LineupSlot, LineupUnit, Location, Opponent
 from .services import (
     cancel_occurrence,
     detach_occurrence,
@@ -34,6 +34,7 @@ from .services import (
     team_no_shows,
 )
 from .services.calendar import add_months, month_bounds, month_grid, season_grid, week_bounds, week_grid
+from .services.lineup import clear_slot, place_member, publish_lineup
 from .services.rbihf_import import RBIHFImportError, apply_plan, build_plan, extract_team_id, parse_fixtures, suggested_location, suggested_opponent
 from .services.referees import RefereeAssignmentError, add_external_referee, assign_referee, conflicting_events, eligible_referees, needs_referee_management, remove_referee, set_referee_fee
 from .tasks import send_deadline_reminders
@@ -371,6 +372,101 @@ class AttendanceSyncTests(EventsTestBase):
         self.assertEqual(event.attendances.count(), 0)
 
 
+class LineupServiceTests(EventsTestBase):
+    """events.services.lineup -- place_member/clear_slot/publish_lineup, the
+    write path behind coach mode's C3 screen (mobile/coach_views.py)."""
+
+    def make_game_with_lineup(self, **event_kwargs):
+        event_kwargs.setdefault("kind", Event.EventKind.GAME)
+        event = self.make_event(**event_kwargs)
+        event.teams.add(self.team)
+        lineup = Lineup.objects.create(event=event, team=self.team)
+        unit = LineupUnit.objects.create(lineup=lineup, label="Line 1")
+        slot = LineupSlot.objects.create(unit=unit)
+        return event, lineup, unit, slot
+
+    def test_place_member_fills_the_slot(self):
+        _event, lineup, _unit, slot = self.make_game_with_lineup()
+
+        place_member(lineup, slot, self.alice)
+
+        slot.refresh_from_db()
+        self.assertEqual(slot.member, self.alice)
+
+    def test_place_member_vacates_the_members_other_slot_in_the_same_lineup(self):
+        _event, lineup, unit, slot = self.make_game_with_lineup()
+        other_slot = LineupSlot.objects.create(unit=unit, ordering=1, member=self.alice)
+
+        place_member(lineup, slot, self.alice)
+
+        other_slot.refresh_from_db()
+        self.assertIsNone(other_slot.member)
+        slot.refresh_from_db()
+        self.assertEqual(slot.member, self.alice)
+
+    def test_place_member_bumps_whoever_was_already_in_the_slot(self):
+        _event, lineup, _unit, slot = self.make_game_with_lineup()
+        slot.member = self.bob
+        slot.save()
+
+        place_member(lineup, slot, self.alice)
+
+        slot.refresh_from_db()
+        self.assertEqual(slot.member, self.alice)
+        # Bumped, not swapped -- Bob doesn't land in any other slot.
+        self.assertFalse(LineupSlot.objects.filter(unit__lineup=lineup, member=self.bob).exists())
+
+    def test_clear_slot_empties_it(self):
+        _event, _lineup, _unit, slot = self.make_game_with_lineup()
+        slot.member = self.alice
+        slot.save()
+
+        clear_slot(slot)
+
+        slot.refresh_from_db()
+        self.assertIsNone(slot.member)
+
+    def test_publish_sets_published_at(self):
+        _event, lineup, _unit, _slot = self.make_game_with_lineup()
+
+        publish_lineup(lineup)
+
+        lineup.refresh_from_db()
+        self.assertIsNotNone(lineup.published_at)
+
+    def test_publish_selects_slotted_members_and_not_selects_the_rest(self):
+        event, lineup, _unit, slot = self.make_game_with_lineup()
+        slot.member = self.alice
+        slot.save()
+        Attendance.objects.update_or_create(event=event, member=self.alice, defaults={"status": Attendance.AttendanceStatus.PRESENT})
+        Attendance.objects.update_or_create(event=event, member=self.bob, defaults={"status": Attendance.AttendanceStatus.PRESENT})
+
+        publish_lineup(lineup)
+
+        self.assertEqual(Attendance.objects.get(event=event, member=self.alice).status, Attendance.AttendanceStatus.SELECTED)
+        self.assertEqual(Attendance.objects.get(event=event, member=self.bob).status, Attendance.AttendanceStatus.NOT_SELECTED)
+
+    def test_publish_leaves_unavailable_members_untouched(self):
+        event, lineup, _unit, _slot = self.make_game_with_lineup()
+        Attendance.objects.update_or_create(event=event, member=self.bob, defaults={"status": Attendance.AttendanceStatus.ABSENT})
+
+        publish_lineup(lineup)
+
+        self.assertEqual(Attendance.objects.get(event=event, member=self.bob).status, Attendance.AttendanceStatus.ABSENT)
+
+    def test_publish_notifies_only_selected_members(self):
+        event, lineup, _unit, slot = self.make_game_with_lineup()
+        slot.member = self.alice
+        slot.save()
+        Attendance.objects.update_or_create(event=event, member=self.alice, defaults={"status": Attendance.AttendanceStatus.PRESENT})
+        Attendance.objects.update_or_create(event=event, member=self.bob, defaults={"status": Attendance.AttendanceStatus.PRESENT})
+
+        publish_lineup(lineup)
+
+        notified_member_ids = set(Notification.objects.filter(member__in=[self.alice, self.bob]).values_list("member_id", flat=True))
+        self.assertEqual(notified_member_ids, {self.alice.pk})
+
+
 class RosterChangeSyncTests(EventsTestBase):
     def test_adding_roster_member_syncs_future_events(self):
         event = self.make_event()