diff --git a/.gitignore b/.gitignore
index 446e4e1..c09ab17 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 /docker/data
 /.claude
 CLAUDE.md
+/coverage
\ No newline at end of file
diff --git a/backend/app/Domain/CalendarSlot/Policies/CalendarSlotPolicy.php b/backend/app/Domain/CalendarSlot/Policies/CalendarSlotPolicy.php
new file mode 100644
index 0000000..a23d08b
--- /dev/null
+++ b/backend/app/Domain/CalendarSlot/Policies/CalendarSlotPolicy.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace App\Domain\CalendarSlot\Policies;
+
+use App\Models\User;
+use App\Models\CalendarSlot;
+use App\Models\Trip;
+
+class CalendarSlotPolicy
+{
+    /**
+     * Determine if the user can view calendar slots for the given trip
+     */
+    public function viewAny(User $user, Trip $trip): bool
+    {
+        return $trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can update the calendar slot
+     */
+    public function update(User $user, CalendarSlot $calendarSlot): bool
+    {
+        return $calendarSlot->trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can reorder items in the calendar slot
+     */
+    public function reorder(User $user, CalendarSlot $calendarSlot): bool
+    {
+        return $calendarSlot->trip->created_by_user_id === $user->id;
+    }
+}
diff --git a/backend/app/Domain/PlannableItem/Policies/PlannableItemPolicy.php b/backend/app/Domain/PlannableItem/Policies/PlannableItemPolicy.php
new file mode 100644
index 0000000..0bb267b
--- /dev/null
+++ b/backend/app/Domain/PlannableItem/Policies/PlannableItemPolicy.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace App\Domain\PlannableItem\Policies;
+
+use App\Models\User;
+use App\Models\PlannableItem;
+use App\Models\Trip;
+
+class PlannableItemPolicy
+{
+    /**
+     * Determine if the user can create a plannable item for the given trip
+     */
+    public function create(User $user, Trip $trip): bool
+    {
+        return $trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can view the plannable item
+     */
+    public function view(User $user, PlannableItem $plannableItem): bool
+    {
+        return $plannableItem->trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can update the plannable item
+     */
+    public function update(User $user, PlannableItem $plannableItem): bool
+    {
+        return $plannableItem->trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can delete the plannable item
+     */
+    public function delete(User $user, PlannableItem $plannableItem): bool
+    {
+        return $plannableItem->trip->created_by_user_id === $user->id;
+    }
+}
diff --git a/backend/app/Domain/PlannedItem/Actions/CreatePlannedItemAction.php b/backend/app/Domain/PlannedItem/Actions/CreatePlannedItemAction.php
new file mode 100644
index 0000000..ed2523a
--- /dev/null
+++ b/backend/app/Domain/PlannedItem/Actions/CreatePlannedItemAction.php
@@ -0,0 +1,104 @@
+<?php
+
+namespace App\Domain\PlannedItem\Actions;
+
+use App\Domain\Trip\Services\CalendarSlotService;
+use App\Models\PlannableItem;
+use App\Models\CalendarSlot;
+use App\Models\PlannedItem;
+use Carbon\Carbon;
+
+class CreatePlannedItemAction
+{
+    public function __construct(
+        private CalendarSlotService $calendarSlotService
+    ) {}
+
+    /**
+     * Create a new planned item from datetime parameters
+     *
+     * @param array $data ['plannable_item_id', 'trip_id', 'start_datetime', 'end_datetime', 'sort_order'?]
+     * @return CalendarSlot The calendar slot with loaded planned items
+     * @throws \Exception
+     */
+    public function execute(array $data): CalendarSlot
+    {
+        $startDatetime = Carbon::parse($data['start_datetime']);
+        $endDatetime = Carbon::parse($data['end_datetime']);
+        $slotDate = $startDatetime->toDateString();
+
+        // Verify the plannable item belongs to the trip
+        $plannableItem = PlannableItem::findOrFail($data['plannable_item_id']);
+        if ($plannableItem->trip_id !== $data['trip_id']) {
+            throw new \Exception('Plannable item does not belong to this trip');
+        }
+
+        // Use database transaction to prevent race conditions
+        $calendarSlot = \DB::transaction(function () use ($data, $plannableItem, $startDatetime, $endDatetime, $slotDate) {
+            // Use firstOrCreate to prevent duplicate slots with same times
+            $calendarSlot = CalendarSlot::firstOrCreate(
+                [
+                    'trip_id' => $data['trip_id'],
+                    'datetime_start' => $startDatetime,
+                    'datetime_end' => $endDatetime,
+                    'slot_date' => $slotDate,
+                ],
+                [
+                    'name' => $plannableItem->name,
+                    'slot_order' => 0, // Will be recalculated
+                ]
+            );
+
+            // Recalculate slot orders to ensure consistency
+            $this->calendarSlotService->recalculateSlotOrdersForDate(
+                $data['trip_id'],
+                $slotDate
+            );
+
+            // Create PlannedItem link (use firstOrCreate to prevent race condition duplicates)
+            PlannedItem::firstOrCreate(
+                [
+                    'plannable_item_id' => $data['plannable_item_id'],
+                    'calendar_slot_id' => $calendarSlot->id,
+                ],
+                [
+                    'sort_order' => $data['sort_order'] ?? 0,
+                ]
+            );
+
+            return $calendarSlot;
+        });
+
+        return $calendarSlot->load(['plannedItems.plannableItem']);
+    }
+
+    /**
+     * Create planned item from existing calendar slot (legacy flow)
+     *
+     * @param array $data ['plannable_item_id', 'calendar_slot_id', 'sort_order'?]
+     * @return PlannedItem
+     * @throws \Exception
+     */
+    public function executeFromSlot(array $data): PlannedItem
+    {
+        // Validate that calendar slot and plannable item belong to the same trip
+        $plannableItem = PlannableItem::findOrFail($data['plannable_item_id']);
+        $calendarSlot = CalendarSlot::findOrFail($data['calendar_slot_id']);
+
+        if ($plannableItem->trip_id !== $calendarSlot->trip_id) {
+            throw new \Exception('Calendar slot and plannable item must belong to the same trip');
+        }
+
+        $plannedItem = PlannedItem::updateOrCreate(
+            [
+                'plannable_item_id' => $data['plannable_item_id'],
+                'calendar_slot_id' => $data['calendar_slot_id'],
+            ],
+            [
+                'sort_order' => $data['sort_order'] ?? 0,
+            ]
+        );
+
+        return $plannedItem->load(['plannableItem', 'calendarSlot']);
+    }
+}
diff --git a/backend/app/Domain/PlannedItem/Actions/DeletePlannedItemAction.php b/backend/app/Domain/PlannedItem/Actions/DeletePlannedItemAction.php
new file mode 100644
index 0000000..cfc43bf
--- /dev/null
+++ b/backend/app/Domain/PlannedItem/Actions/DeletePlannedItemAction.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace App\Domain\PlannedItem\Actions;
+
+use App\Models\PlannedItem;
+
+class DeletePlannedItemAction
+{
+    /**
+     * Delete a planned item
+     *
+     * @param PlannedItem $plannedItem
+     * @return void
+     */
+    public function execute(PlannedItem $plannedItem): void
+    {
+        $plannedItem->delete();
+    }
+}
diff --git a/backend/app/Domain/PlannedItem/Actions/UpdatePlannedItemAction.php b/backend/app/Domain/PlannedItem/Actions/UpdatePlannedItemAction.php
new file mode 100644
index 0000000..88b89c8
--- /dev/null
+++ b/backend/app/Domain/PlannedItem/Actions/UpdatePlannedItemAction.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Domain\PlannedItem\Actions;
+
+use App\Models\PlannedItem;
+
+class UpdatePlannedItemAction
+{
+    /**
+     * Update a planned item's properties
+     *
+     * @param PlannedItem $plannedItem
+     * @param array $data ['calendar_slot_id'?, 'sort_order'?]
+     * @return PlannedItem
+     */
+    public function execute(PlannedItem $plannedItem, array $data): PlannedItem
+    {
+        $plannedItem->update($data);
+
+        return $plannedItem->load(['plannableItem', 'calendarSlot']);
+    }
+}
diff --git a/backend/app/Domain/PlannedItem/Policies/PlannedItemPolicy.php b/backend/app/Domain/PlannedItem/Policies/PlannedItemPolicy.php
new file mode 100644
index 0000000..fec6fc2
--- /dev/null
+++ b/backend/app/Domain/PlannedItem/Policies/PlannedItemPolicy.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Domain\PlannedItem\Policies;
+
+use App\Models\User;
+use App\Models\PlannedItem;
+use App\Models\Trip;
+
+class PlannedItemPolicy
+{
+    /**
+     * Determine if the user can create a planned item for the given trip
+     */
+    public function create(User $user, int $tripId): bool
+    {
+        return \DB::table('trips')
+            ->where('id', $tripId)
+            ->where('created_by_user_id', $user->id)
+            ->exists();
+    }
+
+    /**
+     * Determine if the user can update the planned item
+     */
+    public function update(User $user, PlannedItem $plannedItem): bool
+    {
+        return \DB::table('planned_items')
+            ->join('calendar_slots', 'planned_items.calendar_slot_id', '=', 'calendar_slots.id')
+            ->join('trips', 'calendar_slots.trip_id', '=', 'trips.id')
+            ->where('planned_items.id', $plannedItem->id)
+            ->where('trips.created_by_user_id', $user->id)
+            ->exists();
+    }
+
+    /**
+     * Determine if the user can delete the planned item
+     */
+    public function delete(User $user, PlannedItem $plannedItem): bool
+    {
+        return $this->update($user, $plannedItem);
+    }
+
+    /**
+     * Determine if the user can move a planned item to a new calendar slot
+     */
+    public function moveToSlot(User $user, int $calendarSlotId): bool
+    {
+        return \DB::table('calendar_slots')
+            ->join('trips', 'calendar_slots.trip_id', '=', 'trips.id')
+            ->where('calendar_slots.id', $calendarSlotId)
+            ->where('trips.created_by_user_id', $user->id)
+            ->exists();
+    }
+}
diff --git a/backend/app/Domain/Trip/Policies/TripPolicy.php b/backend/app/Domain/Trip/Policies/TripPolicy.php
new file mode 100644
index 0000000..5b7ea87
--- /dev/null
+++ b/backend/app/Domain/Trip/Policies/TripPolicy.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace App\Domain\Trip\Policies;
+
+use App\Models\User;
+use App\Models\Trip;
+
+class TripPolicy
+{
+    /**
+     * Determine if the user can view the trip
+     */
+    public function view(User $user, Trip $trip): bool
+    {
+        return $trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can update the trip
+     */
+    public function update(User $user, Trip $trip): bool
+    {
+        return $trip->created_by_user_id === $user->id;
+    }
+
+    /**
+     * Determine if the user can delete the trip
+     */
+    public function delete(User $user, Trip $trip): bool
+    {
+        return $trip->created_by_user_id === $user->id;
+    }
+}
diff --git a/backend/app/Domain/Trip/Services/CalendarSlotService.php b/backend/app/Domain/Trip/Services/CalendarSlotService.php
index 24fa3b1..a7d84df 100644
--- a/backend/app/Domain/Trip/Services/CalendarSlotService.php
+++ b/backend/app/Domain/Trip/Services/CalendarSlotService.php
@@ -69,4 +69,43 @@ public function deleteSlotsForTrip(Trip $trip): void
     {
         $trip->calendarSlots()->delete();
     }
+
+    /**
+     * Calculate the slot_order for a new slot based on datetime_start
+     * Orders chronologically by start time within the same day
+     */
+    public function calculateSlotOrder(int $tripId, string $slotDate, Carbon $datetimeStart): int
+    {
+        $maxOrder = CalendarSlot::where('trip_id', $tripId)
+            ->where('slot_date', $slotDate)
+            ->where('datetime_start', '<', $datetimeStart)
+            ->max('slot_order');
+
+        return ($maxOrder ?? -1) + 1;
+    }
+
+    /**
+     * Recalculate slot_order for all slots on a given date
+     * Orders by datetime_start ASC
+     * Uses database transaction with individual updates for safety
+     */
+    public function recalculateSlotOrdersForDate(int $tripId, string $slotDate): void
+    {
+        $slots = CalendarSlot::where('trip_id', $tripId)
+            ->where('slot_date', $slotDate)
+            ->orderBy('datetime_start')
+            ->get();
+
+        if ($slots->isEmpty()) {
+            return;
+        }
+
+        // Update each slot's order within a transaction
+        \DB::transaction(function () use ($slots) {
+            foreach ($slots as $index => $slot) {
+                $slot->slot_order = $index;
+                $slot->save();
+            }
+        });
+    }
 }
\ No newline at end of file
diff --git a/backend/app/Infrastructure/Http/Controllers/API/CalendarSlot/CalendarSlotController.php b/backend/app/Infrastructure/Http/Controllers/API/CalendarSlot/CalendarSlotController.php
index 5051908..58b1d76 100644
--- a/backend/app/Infrastructure/Http/Controllers/API/CalendarSlot/CalendarSlotController.php
+++ b/backend/app/Infrastructure/Http/Controllers/API/CalendarSlot/CalendarSlotController.php
@@ -2,6 +2,7 @@
 
 namespace App\Infrastructure\Http\Controllers\API\CalendarSlot;
 
+use App\Domain\CalendarSlot\Policies\CalendarSlotPolicy;
 use App\Infrastructure\Http\Controllers\Controller;
 use App\Models\CalendarSlot;
 use App\Models\Trip;
@@ -11,16 +12,19 @@
 
 class CalendarSlotController extends Controller
 {
+    public function __construct(
+        private CalendarSlotPolicy $policy
+    ) {}
     public function index(Trip $trip): JsonResponse
     {
-        // Check if user owns the trip
-        if ($trip->created_by_user_id !== auth()->id()) {
+        if (!$this->policy->viewAny(auth()->user(), $trip)) {
             return response()->json(['message' => 'Forbidden'], 403);
         }
 
         $calendarSlots = $trip->calendarSlots()
-            ->with(['plannableItems'])
-            ->orderBy('slot_order')
+            ->with(['plannedItems.plannableItem'])
+            ->orderBy('slot_date')
+            ->orderBy('datetime_start')
             ->get();
 
         return response()->json(['data' => $calendarSlots]);
@@ -28,8 +32,7 @@ public function index(Trip $trip): JsonResponse
 
     public function update(Request $request, CalendarSlot $calendarSlot): JsonResponse
     {
-        // Check if user owns the trip
-        if ($calendarSlot->trip->created_by_user_id !== auth()->id()) {
+        if (!$this->policy->update(auth()->user(), $calendarSlot)) {
             return response()->json(['message' => 'Forbidden'], 403);
         }
 
@@ -44,18 +47,35 @@ public function update(Request $request, CalendarSlot $calendarSlot): JsonRespon
 
     public function reorder(Request $request, CalendarSlot $calendarSlot): JsonResponse
     {
+        if (!$this->policy->reorder(auth()->user(), $calendarSlot)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
+
         $validated = $request->validate([
             'items' => 'required|array',
             'items.*.plannable_item_id' => 'required|exists:plannable_items,id',
             'items.*.sort_order' => 'required|integer',
         ]);
 
+        // Validate all plannable items belong to the same trip
+        $trip = $calendarSlot->trip;
+        $validPlannableItemIds = $trip->plannableItems()->pluck('id')->toArray();
+
         foreach ($validated['items'] as $item) {
-            PlannedItem::where('calendar_slot_id', $calendarSlot->id)
-                ->where('plannable_item_id', $item['plannable_item_id'])
-                ->update(['sort_order' => $item['sort_order']]);
+            if (!in_array($item['plannable_item_id'], $validPlannableItemIds)) {
+                return response()->json(['message' => 'Invalid plannable item for this trip'], 422);
+            }
         }
 
+        // Update sort orders in transaction
+        \DB::transaction(function () use ($validated, $calendarSlot) {
+            foreach ($validated['items'] as $item) {
+                PlannedItem::where('calendar_slot_id', $calendarSlot->id)
+                    ->where('plannable_item_id', $item['plannable_item_id'])
+                    ->update(['sort_order' => $item['sort_order']]);
+            }
+        });
+
         return response()->json(['message' => 'Items reordered successfully']);
     }
 }
\ No newline at end of file
diff --git a/backend/app/Infrastructure/Http/Controllers/API/PlannableItem/PlannableItemController.php b/backend/app/Infrastructure/Http/Controllers/API/PlannableItem/PlannableItemController.php
index 2d3bb0f..5ed4cb3 100644
--- a/backend/app/Infrastructure/Http/Controllers/API/PlannableItem/PlannableItemController.php
+++ b/backend/app/Infrastructure/Http/Controllers/API/PlannableItem/PlannableItemController.php
@@ -2,6 +2,7 @@
 
 namespace App\Infrastructure\Http\Controllers\API\PlannableItem;
 
+use App\Domain\PlannableItem\Policies\PlannableItemPolicy;
 use App\Infrastructure\Http\Controllers\Controller;
 use App\Models\PlannableItem;
 use App\Models\Trip;
@@ -10,10 +11,12 @@
 
 class PlannableItemController extends Controller
 {
+    public function __construct(
+        private PlannableItemPolicy $policy
+    ) {}
     public function index(Trip $trip): JsonResponse
     {
-        // Check if user owns the trip
-        if ($trip->created_by_user_id !== auth()->id()) {
+        if (!$this->policy->create(auth()->user(), $trip)) {
             return response()->json(['message' => 'Forbidden'], 403);
         }
 
@@ -26,8 +29,7 @@ public function index(Trip $trip): JsonResponse
 
     public function store(Request $request, Trip $trip): JsonResponse
     {
-        // Check if user owns the trip
-        if ($trip->created_by_user_id !== auth()->id()) {
+        if (!$this->policy->create(auth()->user(), $trip)) {
             return response()->json(['message' => 'Forbidden'], 403);
         }
 
@@ -46,14 +48,17 @@ public function store(Request $request, Trip $trip): JsonResponse
 
     public function show(PlannableItem $plannableItem): JsonResponse
     {
+        if (!$this->policy->view(auth()->user(), $plannableItem)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
+
         $plannableItem->load(['calendarSlots', 'trip']);
         return response()->json($plannableItem);
     }
 
     public function update(Request $request, PlannableItem $plannableItem): JsonResponse
     {
-        // Check if user owns the trip
-        if ($plannableItem->trip->created_by_user_id !== auth()->id()) {
+        if (!$this->policy->update(auth()->user(), $plannableItem)) {
             return response()->json(['message' => 'Forbidden'], 403);
         }
 
@@ -72,6 +77,10 @@ public function update(Request $request, PlannableItem $plannableItem): JsonResp
 
     public function destroy(PlannableItem $plannableItem): JsonResponse
     {
+        if (!$this->policy->delete(auth()->user(), $plannableItem)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
+
         $plannableItem->delete();
 
         return response()->json(null, 204);
diff --git a/backend/app/Infrastructure/Http/Controllers/API/PlannedItem/PlannedItemController.php b/backend/app/Infrastructure/Http/Controllers/API/PlannedItem/PlannedItemController.php
index 0c93c77..07b894a 100644
--- a/backend/app/Infrastructure/Http/Controllers/API/PlannedItem/PlannedItemController.php
+++ b/backend/app/Infrastructure/Http/Controllers/API/PlannedItem/PlannedItemController.php
@@ -2,51 +2,90 @@
 
 namespace App\Infrastructure\Http\Controllers\API\PlannedItem;
 
+use App\Domain\PlannedItem\Actions\CreatePlannedItemAction;
+use App\Domain\PlannedItem\Actions\UpdatePlannedItemAction;
+use App\Domain\PlannedItem\Actions\DeletePlannedItemAction;
+use App\Domain\PlannedItem\Policies\PlannedItemPolicy;
 use App\Infrastructure\Http\Controllers\Controller;
 use App\Models\PlannedItem;
-use App\Models\PlannableItem;
-use App\Models\CalendarSlot;
 use Illuminate\Http\Request;
 use Illuminate\Http\JsonResponse;
+use Illuminate\Support\Facades\Gate;
 
 class PlannedItemController extends Controller
 {
+    public function __construct(
+        private CreatePlannedItemAction $createAction,
+        private UpdatePlannedItemAction $updateAction,
+        private DeletePlannedItemAction $deleteAction,
+        private PlannedItemPolicy $policy
+    ) {}
+
     public function store(Request $request): JsonResponse
     {
         $validated = $request->validate([
             'plannable_item_id' => 'required|exists:plannable_items,id',
-            'calendar_slot_id' => 'required|exists:calendar_slots,id',
+            'trip_id' => 'required|exists:trips,id',
+            'start_datetime' => 'required|date',
+            'end_datetime' => 'required|date|after:start_datetime',
+            'calendar_slot_id' => 'sometimes|exists:calendar_slots,id',
             'sort_order' => 'nullable|integer',
         ]);
 
-        $plannedItem = PlannedItem::updateOrCreate(
-            [
-                'plannable_item_id' => $validated['plannable_item_id'],
-                'calendar_slot_id' => $validated['calendar_slot_id'],
-            ],
-            [
-                'sort_order' => $validated['sort_order'] ?? 0,
-            ]
-        );
+        // Check authorization using Policy
+        if (!$this->policy->create(auth()->user(), $validated['trip_id'])) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
 
-        return response()->json($plannedItem->load(['plannableItem', 'calendarSlot']), 201);
+        // If calendar_slot_id is provided, use existing flow (backward compatibility)
+        if (isset($validated['calendar_slot_id'])) {
+            $plannedItem = $this->createAction->executeFromSlot($validated);
+            return response()->json($plannedItem, 201);
+        }
+
+        // New flow: Create CalendarSlot from datetime using Action
+        try {
+            $calendarSlot = $this->createAction->execute($validated);
+            return response()->json($calendarSlot, 201);
+        } catch (\Exception $e) {
+            return response()->json(['message' => $e->getMessage()], 422);
+        }
     }
 
     public function update(Request $request, PlannedItem $plannedItem): JsonResponse
     {
+        // Check authorization using Policy
+        if (!$this->policy->update(auth()->user(), $plannedItem)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
+
         $validated = $request->validate([
             'calendar_slot_id' => 'sometimes|required|exists:calendar_slots,id',
             'sort_order' => 'nullable|integer',
         ]);
 
-        $plannedItem->update($validated);
+        // If changing calendar slot, verify user owns the new slot's trip
+        if (isset($validated['calendar_slot_id'])) {
+            if (!$this->policy->moveToSlot(auth()->user(), $validated['calendar_slot_id'])) {
+                return response()->json(['message' => 'Forbidden'], 403);
+            }
+        }
 
-        return response()->json($plannedItem->load(['plannableItem', 'calendarSlot']));
+        // Execute update using Action
+        $updatedItem = $this->updateAction->execute($plannedItem, $validated);
+
+        return response()->json($updatedItem);
     }
 
     public function destroy(PlannedItem $plannedItem): JsonResponse
     {
-        $plannedItem->delete();
+        // Check authorization using Policy
+        if (!$this->policy->delete(auth()->user(), $plannedItem)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
+
+        // Execute delete using Action
+        $this->deleteAction->execute($plannedItem);
 
         return response()->json(null, 204);
     }
diff --git a/backend/app/Infrastructure/Http/Controllers/API/Trip/TripController.php b/backend/app/Infrastructure/Http/Controllers/API/Trip/TripController.php
index d17bdc6..19bf89b 100644
--- a/backend/app/Infrastructure/Http/Controllers/API/Trip/TripController.php
+++ b/backend/app/Infrastructure/Http/Controllers/API/Trip/TripController.php
@@ -2,14 +2,17 @@
 
 namespace App\Infrastructure\Http\Controllers\API\Trip;
 
+use App\Domain\Trip\Policies\TripPolicy;
 use App\Infrastructure\Http\Controllers\Controller;
 use App\Models\Trip;
 use Illuminate\Http\Request;
 use Illuminate\Http\JsonResponse;
-use Illuminate\Validation\ValidationException;
 
 class TripController extends Controller
 {
+    public function __construct(
+        private TripPolicy $policy
+    ) {}
     /**
      * Display a listing of the resource.
      */
@@ -44,11 +47,11 @@ public function store(Request $request): JsonResponse
     /**
      * Display the specified resource.
      */
-    public function show(Request $request, string $id): JsonResponse
+    public function show(Request $request, Trip $trip): JsonResponse
     {
-        $trip = Trip::where('id', $id)
-            ->where('created_by_user_id', $request->user()->id)
-            ->firstOrFail();
+        if (!$this->policy->view($request->user(), $trip)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
 
         return response()->json(['data' => $trip]);
     }
@@ -56,11 +59,11 @@ public function show(Request $request, string $id): JsonResponse
     /**
      * Update the specified resource in storage.
      */
-    public function update(Request $request, string $id): JsonResponse
+    public function update(Request $request, Trip $trip): JsonResponse
     {
-        $trip = Trip::where('id', $id)
-            ->where('created_by_user_id', $request->user()->id)
-            ->firstOrFail();
+        if (!$this->policy->update($request->user(), $trip)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
 
         $validated = $request->validate([
             'name' => 'required|string|max:255',
@@ -77,11 +80,11 @@ public function update(Request $request, string $id): JsonResponse
     /**
      * Remove the specified resource from storage.
      */
-    public function destroy(Request $request, string $id): JsonResponse
+    public function destroy(Request $request, Trip $trip): JsonResponse
     {
-        $trip = Trip::where('id', $id)
-            ->where('created_by_user_id', $request->user()->id)
-            ->firstOrFail();
+        if (!$this->policy->delete($request->user(), $trip)) {
+            return response()->json(['message' => 'Forbidden'], 403);
+        }
 
         $trip->delete();
 
diff --git a/backend/database/migrations/2025_09_28_064407_create_calendar_slots_table.php b/backend/database/migrations/2025_09_28_064407_create_calendar_slots_table.php
index fa145c9..940a299 100644
--- a/backend/database/migrations/2025_09_28_064407_create_calendar_slots_table.php
+++ b/backend/database/migrations/2025_09_28_064407_create_calendar_slots_table.php
@@ -21,8 +21,9 @@ public function up(): void
             $table->integer('slot_order')->default(0);
             $table->timestamps();
 
-            $table->index(['trip_id', 'slot_date']);
-            $table->index(['trip_id', 'slot_order']);
+            // Composite indexes for performance
+            $table->index(['trip_id', 'slot_date', 'datetime_start']);
+            $table->index(['trip_id', 'slot_date', 'slot_order']);
         });
     }
 
diff --git a/backend/tests/Feature/CalendarSlotTest.php b/backend/tests/Feature/CalendarSlotTest.php
index edf578e..4efb070 100644
--- a/backend/tests/Feature/CalendarSlotTest.php
+++ b/backend/tests/Feature/CalendarSlotTest.php
@@ -227,4 +227,110 @@ public function test_slots_created_when_dates_added_to_trip()
         $trip->refresh();
         $this->assertCount(2, $trip->calendarSlots);
     }
+
+    public function test_calendar_slots_include_planned_items_with_plannable_item()
+    {
+        $trip = Trip::factory()->create([
+            'created_by_user_id' => $this->user->id,
+            'start_date' => '2024-01-01',
+            'end_date' => '2024-01-01'
+        ]);
+
+        // Create a plannable item and schedule it
+        $plannableItem = \App\Models\PlannableItem::factory()->create([
+            'trip_id' => $trip->id,
+            'name' => 'Eiffel Tower'
+        ]);
+
+        $response = $this->withHeaders([
+            'Authorization' => 'Bearer ' . $this->token,
+            'Accept' => 'application/json'
+        ])->postJson('/api/planned-items', [
+            'plannable_item_id' => $plannableItem->id,
+            'trip_id' => $trip->id,
+            'start_datetime' => '2024-01-01 14:00:00',
+            'end_datetime' => '2024-01-01 16:00:00',
+        ]);
+
+        $response->assertStatus(201);
+
+        // Fetch calendar slots and verify relationships are loaded
+        $slotsResponse = $this->withHeaders([
+            'Authorization' => 'Bearer ' . $this->token,
+            'Accept' => 'application/json'
+        ])->getJson("/api/trips/{$trip->id}/calendar-slots");
+
+        $slotsResponse->assertStatus(200);
+
+        // Find the slot we just created
+        $slots = $slotsResponse->json('data');
+        $scheduledSlot = collect($slots)->firstWhere('name', 'Eiffel Tower');
+
+        $this->assertNotNull($scheduledSlot);
+        $this->assertArrayHasKey('planned_items', $scheduledSlot);
+        $this->assertCount(1, $scheduledSlot['planned_items']);
+        $this->assertArrayHasKey('plannable_item', $scheduledSlot['planned_items'][0]);
+        $this->assertEquals('Eiffel Tower', $scheduledSlot['planned_items'][0]['plannable_item']['name']);
+    }
+
+    public function test_calendar_slots_ordered_by_date_and_time()
+    {
+        $trip = Trip::factory()->create([
+            'created_by_user_id' => $this->user->id,
+            'start_date' => '2024-01-01',
+            'end_date' => '2024-01-02'
+        ]);
+
+        // Create plannable items
+        $item1 = \App\Models\PlannableItem::factory()->create(['trip_id' => $trip->id, 'name' => 'Breakfast']);
+        $item2 = \App\Models\PlannableItem::factory()->create(['trip_id' => $trip->id, 'name' => 'Lunch']);
+        $item3 = \App\Models\PlannableItem::factory()->create(['trip_id' => $trip->id, 'name' => 'Dinner Day 1']);
+        $item4 = \App\Models\PlannableItem::factory()->create(['trip_id' => $trip->id, 'name' => 'Breakfast Day 2']);
+
+        // Schedule in non-chronological order
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $item3->id,
+            'trip_id' => $trip->id,
+            'start_datetime' => '2024-01-01 19:00:00',
+            'end_datetime' => '2024-01-01 21:00:00',
+        ]);
+
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $item1->id,
+            'trip_id' => $trip->id,
+            'start_datetime' => '2024-01-01 08:00:00',
+            'end_datetime' => '2024-01-01 09:00:00',
+        ]);
+
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $item4->id,
+            'trip_id' => $trip->id,
+            'start_datetime' => '2024-01-02 08:00:00',
+            'end_datetime' => '2024-01-02 09:00:00',
+        ]);
+
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $item2->id,
+            'trip_id' => $trip->id,
+            'start_datetime' => '2024-01-01 12:00:00',
+            'end_datetime' => '2024-01-01 13:00:00',
+        ]);
+
+        // Fetch slots and verify they're ordered correctly
+        $response = $this->withHeaders([
+            'Authorization' => 'Bearer ' . $this->token,
+            'Accept' => 'application/json'
+        ])->getJson("/api/trips/{$trip->id}/calendar-slots");
+
+        $response->assertStatus(200);
+
+        $slots = $response->json('data');
+        $scheduledSlots = collect($slots)->filter(fn($slot) => $slot['datetime_start'] !== null)->values();
+
+        // Should be ordered: Breakfast (Day 1, 8am), Lunch (Day 1, 12pm), Dinner (Day 1, 7pm), Breakfast (Day 2, 8am)
+        $this->assertEquals('Breakfast', $scheduledSlots[0]['name']);
+        $this->assertEquals('Lunch', $scheduledSlots[1]['name']);
+        $this->assertEquals('Dinner Day 1', $scheduledSlots[2]['name']);
+        $this->assertEquals('Breakfast Day 2', $scheduledSlots[3]['name']);
+    }
 }
\ No newline at end of file
diff --git a/backend/tests/Feature/PlannedItemTest.php b/backend/tests/Feature/PlannedItemTest.php
new file mode 100644
index 0000000..b5820ef
--- /dev/null
+++ b/backend/tests/Feature/PlannedItemTest.php
@@ -0,0 +1,321 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\User;
+use App\Models\Trip;
+use App\Models\PlannableItem;
+use App\Models\CalendarSlot;
+use App\Models\PlannedItem;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class PlannedItemTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private User $user;
+    private Trip $trip;
+    private PlannableItem $plannableItem;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->user = User::factory()->create();
+        $this->trip = Trip::factory()->create([
+            'created_by_user_id' => $this->user->id,
+            'start_date' => '2025-01-15',
+            'end_date' => '2025-01-17',
+        ]);
+        $this->plannableItem = PlannableItem::factory()->create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Eiffel Tower',
+        ]);
+    }
+
+    /** @test */
+    public function it_creates_calendar_slot_when_scheduling_item_with_datetime()
+    {
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        $response->assertStatus(201);
+        $this->assertDatabaseHas('calendar_slots', [
+            'trip_id' => $this->trip->id,
+            'name' => 'Eiffel Tower',
+            'slot_date' => '2025-01-15',
+        ]);
+        $this->assertDatabaseHas('planned_items', [
+            'plannable_item_id' => $this->plannableItem->id,
+        ]);
+    }
+
+    /** @test */
+    public function it_calculates_slot_order_correctly()
+    {
+        // Create first slot at 10:00
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 10:00:00',
+            'end_datetime' => '2025-01-15 11:00:00',
+        ]);
+
+        // Create another plannable item
+        $secondItem = PlannableItem::factory()->create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Louvre',
+        ]);
+
+        // Create second slot at 14:00
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $secondItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        // Create third slot at 08:00 (should have slot_order 0 after recalculation)
+        $thirdItem = PlannableItem::factory()->create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Breakfast',
+        ]);
+
+        $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $thirdItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 08:00:00',
+            'end_datetime' => '2025-01-15 09:00:00',
+        ]);
+
+        $slots = CalendarSlot::where('trip_id', $this->trip->id)
+            ->where('slot_date', '2025-01-15')
+            ->orderBy('slot_order')
+            ->get();
+
+        // After recalculation, order should be by datetime_start
+        $this->assertEquals('Breakfast', $slots[0]->name);
+        $this->assertEquals(0, $slots[0]->slot_order);
+        $this->assertEquals('Eiffel Tower', $slots[1]->name);
+        $this->assertEquals(1, $slots[1]->slot_order);
+        $this->assertEquals('Louvre', $slots[2]->name);
+        $this->assertEquals(2, $slots[2]->slot_order);
+    }
+
+    /** @test */
+    public function it_validates_end_time_is_after_start_time()
+    {
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 16:00:00',
+            'end_datetime' => '2025-01-15 14:00:00',
+        ]);
+
+        $response->assertStatus(422);
+    }
+
+    /** @test */
+    public function it_requires_plannable_item_to_belong_to_trip()
+    {
+        $otherTrip = Trip::factory()->create([
+            'created_by_user_id' => $this->user->id,
+        ]);
+        $otherItem = PlannableItem::factory()->create([
+            'trip_id' => $otherTrip->id,
+        ]);
+
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $otherItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        $response->assertStatus(422);
+        $response->assertJson([
+            'error' => 'Plannable item does not belong to this trip'
+        ]);
+    }
+
+    /** @test */
+    public function it_supports_backward_compatible_calendar_slot_id_flow()
+    {
+        $calendarSlot = CalendarSlot::factory()->create([
+            'trip_id' => $this->trip->id,
+        ]);
+
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'calendar_slot_id' => $calendarSlot->id,
+        ]);
+
+        $response->assertStatus(201);
+        $this->assertDatabaseHas('planned_items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'calendar_slot_id' => $calendarSlot->id,
+        ]);
+    }
+
+    /** @test */
+    public function it_requires_authentication_to_create_planned_item()
+    {
+        $response = $this->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        $response->assertStatus(401);
+    }
+
+    /** @test */
+    public function it_validates_required_fields()
+    {
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', []);
+
+        $response->assertStatus(422);
+        $response->assertJsonValidationErrors(['plannable_item_id', 'trip_id', 'start_datetime', 'end_datetime']);
+    }
+
+    /** @test */
+    public function it_validates_plannable_item_exists()
+    {
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => 99999,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        $response->assertStatus(422);
+        $response->assertJsonValidationErrors(['plannable_item_id']);
+    }
+
+    /** @test */
+    public function it_validates_trip_exists()
+    {
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'trip_id' => 99999,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        $response->assertStatus(422);
+        $response->assertJsonValidationErrors(['trip_id']);
+    }
+
+    /** @test */
+    public function it_returns_calendar_slot_with_relationships()
+    {
+        $response = $this->actingAs($this->user)->postJson('/api/planned-items', [
+            'plannable_item_id' => $this->plannableItem->id,
+            'trip_id' => $this->trip->id,
+            'start_datetime' => '2025-01-15 14:00:00',
+            'end_datetime' => '2025-01-15 16:00:00',
+        ]);
+
+        $response->assertStatus(201);
+        $response->assertJsonStructure([
+            'id',
+            'trip_id',
+            'name',
+            'datetime_start',
+            'datetime_end',
+            'slot_date',
+            'slot_order',
+            'planned_items' => [
+                '*' => [
+                    'id',
+                    'plannable_item_id',
+                    'calendar_slot_id',
+                    'plannable_item' => [
+                        'id',
+                        'name',
+                        'trip_id',
+                    ]
+                ]
+            ]
+        ]);
+    }
+
+    /** @test */
+    public function it_can_update_planned_item_slot()
+    {
+        $calendarSlot1 = CalendarSlot::factory()->create(['trip_id' => $this->trip->id]);
+        $calendarSlot2 = CalendarSlot::factory()->create(['trip_id' => $this->trip->id]);
+
+        $plannedItem = PlannedItem::create([
+            'plannable_item_id' => $this->plannableItem->id,
+            'calendar_slot_id' => $calendarSlot1->id,
+            'sort_order' => 0,
+        ]);
+
+        $response = $this->actingAs($this->user)->putJson("/api/planned-items/{$plannedItem->id}", [
+            'calendar_slot_id' => $calendarSlot2->id,
+            'sort_order' => 5,
+        ]);
+
+        $response->assertStatus(200);
+        $this->assertDatabaseHas('planned_items', [
+            'id' => $plannedItem->id,
+            'calendar_slot_id' => $calendarSlot2->id,
+            'sort_order' => 5,
+        ]);
+    }
+
+    /** @test */
+    public function it_can_delete_planned_item()
+    {
+        $calendarSlot = CalendarSlot::factory()->create(['trip_id' => $this->trip->id]);
+        $plannedItem = PlannedItem::create([
+            'plannable_item_id' => $this->plannableItem->id,
+            'calendar_slot_id' => $calendarSlot->id,
+            'sort_order' => 0,
+        ]);
+
+        $response = $this->actingAs($this->user)->deleteJson("/api/planned-items/{$plannedItem->id}");
+
+        $response->assertStatus(204);
+        $this->assertDatabaseMissing('planned_items', [
+            'id' => $plannedItem->id,
+        ]);
+    }
+
+    /** @test */
+    public function it_requires_authentication_to_update_planned_item()
+    {
+        $calendarSlot = CalendarSlot::factory()->create(['trip_id' => $this->trip->id]);
+        $plannedItem = PlannedItem::create([
+            'plannable_item_id' => $this->plannableItem->id,
+            'calendar_slot_id' => $calendarSlot->id,
+        ]);
+
+        $response = $this->putJson("/api/planned-items/{$plannedItem->id}", [
+            'sort_order' => 1,
+        ]);
+
+        $response->assertStatus(401);
+    }
+
+    /** @test */
+    public function it_requires_authentication_to_delete_planned_item()
+    {
+        $calendarSlot = CalendarSlot::factory()->create(['trip_id' => $this->trip->id]);
+        $plannedItem = PlannedItem::create([
+            'plannable_item_id' => $this->plannableItem->id,
+            'calendar_slot_id' => $calendarSlot->id,
+        ]);
+
+        $response = $this->deleteJson("/api/planned-items/{$plannedItem->id}");
+
+        $response->assertStatus(401);
+    }
+}
diff --git a/backend/tests/Unit/CalendarSlotServiceTest.php b/backend/tests/Unit/CalendarSlotServiceTest.php
new file mode 100644
index 0000000..68b4ad3
--- /dev/null
+++ b/backend/tests/Unit/CalendarSlotServiceTest.php
@@ -0,0 +1,235 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Domain\Trip\Services\CalendarSlotService;
+use App\Models\Trip;
+use App\Models\CalendarSlot;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+use Carbon\Carbon;
+
+class CalendarSlotServiceTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private CalendarSlotService $service;
+    private Trip $trip;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->service = new CalendarSlotService();
+        $this->trip = Trip::factory()->create([
+            'start_date' => '2024-01-01',
+            'end_date' => '2024-01-03',
+        ]);
+    }
+
+    /** @test */
+    public function it_calculates_slot_order_for_first_slot_on_date()
+    {
+        $order = $this->service->calculateSlotOrder(
+            $this->trip->id,
+            '2024-01-01',
+            Carbon::parse('2024-01-01 10:00:00')
+        );
+
+        $this->assertEquals(0, $order);
+    }
+
+    /** @test */
+    public function it_calculates_slot_order_based_on_chronological_position()
+    {
+        // Create existing slots
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Morning',
+            'datetime_start' => '2024-01-01 08:00:00',
+            'datetime_end' => '2024-01-01 09:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 0,
+        ]);
+
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Afternoon',
+            'datetime_start' => '2024-01-01 14:00:00',
+            'datetime_end' => '2024-01-01 15:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 1,
+        ]);
+
+        // Calculate order for noon slot (should be between morning and afternoon)
+        $order = $this->service->calculateSlotOrder(
+            $this->trip->id,
+            '2024-01-01',
+            Carbon::parse('2024-01-01 12:00:00')
+        );
+
+        $this->assertEquals(1, $order);
+    }
+
+    /** @test */
+    public function it_calculates_slot_order_for_earliest_time()
+    {
+        // Create existing slot
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Late Morning',
+            'datetime_start' => '2024-01-01 10:00:00',
+            'datetime_end' => '2024-01-01 11:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 0,
+        ]);
+
+        // Calculate order for earlier time
+        $order = $this->service->calculateSlotOrder(
+            $this->trip->id,
+            '2024-01-01',
+            Carbon::parse('2024-01-01 08:00:00')
+        );
+
+        $this->assertEquals(0, $order);
+    }
+
+    /** @test */
+    public function it_calculates_slot_order_for_latest_time()
+    {
+        // Create existing slots
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Morning',
+            'datetime_start' => '2024-01-01 08:00:00',
+            'datetime_end' => '2024-01-01 09:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 0,
+        ]);
+
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Noon',
+            'datetime_start' => '2024-01-01 12:00:00',
+            'datetime_end' => '2024-01-01 13:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 1,
+        ]);
+
+        // Calculate order for later time
+        $order = $this->service->calculateSlotOrder(
+            $this->trip->id,
+            '2024-01-01',
+            Carbon::parse('2024-01-01 20:00:00')
+        );
+
+        $this->assertEquals(2, $order);
+    }
+
+    /** @test */
+    public function it_only_considers_slots_from_same_date()
+    {
+        // Create slot on different date
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Other Day',
+            'datetime_start' => '2024-01-02 08:00:00',
+            'datetime_end' => '2024-01-02 09:00:00',
+            'slot_date' => '2024-01-02',
+            'slot_order' => 0,
+        ]);
+
+        // Calculate order for Jan 1 (should start at 0, not affected by Jan 2)
+        $order = $this->service->calculateSlotOrder(
+            $this->trip->id,
+            '2024-01-01',
+            Carbon::parse('2024-01-01 10:00:00')
+        );
+
+        $this->assertEquals(0, $order);
+    }
+
+    /** @test */
+    public function it_recalculates_slot_orders_for_date()
+    {
+        // Create slots in non-chronological slot_order
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Evening',
+            'datetime_start' => '2024-01-01 20:00:00',
+            'datetime_end' => '2024-01-01 21:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 5, // Wrong order
+        ]);
+
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Morning',
+            'datetime_start' => '2024-01-01 08:00:00',
+            'datetime_end' => '2024-01-01 09:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 3, // Wrong order
+        ]);
+
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Afternoon',
+            'datetime_start' => '2024-01-01 14:00:00',
+            'datetime_end' => '2024-01-01 15:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 1, // Wrong order
+        ]);
+
+        // Recalculate
+        $this->service->recalculateSlotOrdersForDate($this->trip->id, '2024-01-01');
+
+        // Verify correct chronological order
+        $slots = CalendarSlot::where('trip_id', $this->trip->id)
+            ->where('slot_date', '2024-01-01')
+            ->orderBy('slot_order')
+            ->get();
+
+        $this->assertEquals('Morning', $slots[0]->name);
+        $this->assertEquals(0, $slots[0]->slot_order);
+
+        $this->assertEquals('Afternoon', $slots[1]->name);
+        $this->assertEquals(1, $slots[1]->slot_order);
+
+        $this->assertEquals('Evening', $slots[2]->name);
+        $this->assertEquals(2, $slots[2]->slot_order);
+    }
+
+    /** @test */
+    public function it_only_recalculates_slots_for_specified_date()
+    {
+        // Create slots on Jan 1
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Jan 1 Slot',
+            'datetime_start' => '2024-01-01 10:00:00',
+            'datetime_end' => '2024-01-01 11:00:00',
+            'slot_date' => '2024-01-01',
+            'slot_order' => 5,
+        ]);
+
+        // Create slots on Jan 2
+        CalendarSlot::create([
+            'trip_id' => $this->trip->id,
+            'name' => 'Jan 2 Slot',
+            'datetime_start' => '2024-01-02 10:00:00',
+            'datetime_end' => '2024-01-02 11:00:00',
+            'slot_date' => '2024-01-02',
+            'slot_order' => 7,
+        ]);
+
+        // Recalculate only Jan 1
+        $this->service->recalculateSlotOrdersForDate($this->trip->id, '2024-01-01');
+
+        // Jan 1 should be recalculated to 0
+        $jan1Slot = CalendarSlot::where('slot_date', '2024-01-01')->first();
+        $this->assertEquals(0, $jan1Slot->slot_order);
+
+        // Jan 2 should remain unchanged
+        $jan2Slot = CalendarSlot::where('slot_date', '2024-01-02')->first();
+        $this->assertEquals(7, $jan2Slot->slot_order);
+    }
+}
diff --git a/docker/backend/Dockerfile.dev b/docker/backend/Dockerfile.dev
index 3bc831e..0974091 100644
--- a/docker/backend/Dockerfile.dev
+++ b/docker/backend/Dockerfile.dev
@@ -41,4 +41,4 @@ RUN mkdir -p storage/app/public storage/framework/cache storage/framework/sessio
 EXPOSE 8000
 
 # Start Laravel development server with composer install
-CMD sh -c "composer install && php artisan key:generate --force && php artisan serve --host=0.0.0.0 --port=8000"
\ No newline at end of file
+CMD sh -c "composer install && php artisan key:generate --force && php artisan migrate --force && php artisan serve --host=0.0.0.0 --port=8000"
\ No newline at end of file
diff --git a/frontend/src/components/TripDetail.css b/frontend/src/components/TripDetail.css
index df4cbea..27ef97c 100644
--- a/frontend/src/components/TripDetail.css
+++ b/frontend/src/components/TripDetail.css
@@ -67,22 +67,26 @@
 /* Content Layout */
 .trip-detail-content {
   flex: 1;
-  display: flex;
+  display: grid;
+  grid-template-columns: 1fr var(--sidebar-width);
   gap: 0;
   height: calc(100vh - var(--header-height));
+  min-height: 0;
+}
+
+.trip-detail-main {
+  padding: var(--spacing-xl);
+  overflow-y: auto;
+  background: var(--color-bg-secondary);
+  order: 1;
 }
 
 .trip-detail-sidebar {
   width: var(--sidebar-width);
   background: var(--color-bg-primary);
-  border-right: 1px solid var(--color-border);
-  overflow-y: auto;
-}
-
-.trip-detail-main {
-  flex: 1;
-  padding: var(--spacing-xl);
+  border-left: 1px solid var(--color-border);
   overflow-y: auto;
+  order: 2;
 }
 
 /* Calendar Placeholder */
@@ -165,19 +169,23 @@
 /* Responsive */
 @media (max-width: 768px) {
   .trip-detail-content {
-    flex-direction: column;
+    grid-template-columns: 1fr;
+    grid-template-rows: auto 1fr;
     height: auto;
   }
 
-  .trip-detail-sidebar {
-    width: 100%;
-    border-right: none;
-    border-bottom: 1px solid var(--color-border);
-    min-height: 400px;
+  .trip-detail-main {
+    order: 2;
+    padding: var(--spacing-md);
   }
 
-  .trip-detail-main {
-    padding: var(--spacing-md);
+  .trip-detail-sidebar {
+    order: 1;
+    width: 100%;
+    border-left: none;
+    border-bottom: 1px solid var(--color-border);
+    min-height: 300px;
+    max-height: 50vh;
   }
 
   .trip-detail-header {
diff --git a/frontend/src/components/TripDetail.jsx b/frontend/src/components/TripDetail.jsx
index 7183be1..85b376b 100644
--- a/frontend/src/components/TripDetail.jsx
+++ b/frontend/src/components/TripDetail.jsx
@@ -3,12 +3,17 @@ import { useParams, useNavigate, Link } from 'react-router-dom';
 import { formatDate } from '../utils/dateFormatter';
 import { useTrip } from '../hooks/useTrip';
 import PlannablesList from './plannables/PlannablesList';
+import TripTimeline from './timeline/TripTimeline';
+import axios from 'axios';
 import './TripDetail.css';
 
+const API_URL = import.meta.env.VITE_API_URL || 'http://localhost:8000';
+
 const TripDetail = () => {
   const { id } = useParams();
   const navigate = useNavigate();
   const [trip, setTrip] = useState(null);
+  const [plannableItems, setPlannableItems] = useState([]);
   const { fetchTrip, loading, error } = useTrip();
 
   useEffect(() => {
@@ -24,6 +29,24 @@ const TripDetail = () => {
     loadTrip();
   }, [id, fetchTrip]);
 
+  useEffect(() => {
+    const loadPlannableItems = async () => {
+      try {
+        const token = localStorage.getItem('token');
+        const response = await axios.get(`${API_URL}/api/trips/${id}/plannables`, {
+          headers: { Authorization: `Bearer ${token}` }
+        });
+        setPlannableItems(response.data.data || []);
+      } catch (err) {
+        console.error('Error loading plannable items:', err);
+      }
+    };
+
+    if (id) {
+      loadPlannableItems();
+    }
+  }, [id]);
+
   // Memoize trip dates display to prevent unnecessary re-renders
   const tripDatesDisplay = useMemo(() => {
     if (!trip) return null;
@@ -79,13 +102,16 @@ const TripDetail = () => {
 
       <div className="trip-detail-content">
         <div className="trip-detail-sidebar">
-          <PlannablesList tripId={trip.id} />
+          <PlannablesList tripId={trip.id} onItemsChange={(items) => setPlannableItems(items)} />
         </div>
         <div className="trip-detail-main">
-          <div className="calendar-placeholder">
-            <h2>Calendar View</h2>
-            <p>Calendar view will be implemented here in the future</p>
-          </div>
+          <TripTimeline
+            trip={trip}
+            plannableItems={plannableItems}
+            onScheduleSuccess={() => {
+              // Optional: refresh plannable items if needed
+            }}
+          />
         </div>
       </div>
     </div>
diff --git a/frontend/src/components/plannables/PlannablesList.jsx b/frontend/src/components/plannables/PlannablesList.jsx
index 3c6833a..cf14b92 100644
--- a/frontend/src/components/plannables/PlannablesList.jsx
+++ b/frontend/src/components/plannables/PlannablesList.jsx
@@ -6,7 +6,7 @@ import PlannableForm from './PlannableForm';
 import ConfirmDialog from '../common/ConfirmDialog';
 import './PlannablesList.css';
 
-const PlannablesList = ({ tripId }) => {
+const PlannablesList = ({ tripId, onItemsChange }) => {
   const { showSuccess, showError } = useToast();
   const {
     fetchBothData,
@@ -46,6 +46,11 @@ const PlannablesList = ({ tripId }) => {
         const limitedCalendarSlots = calendarSlots.slice(0, 365); // Max 1 year of slots
         setCalendarSlots(limitedCalendarSlots);
 
+        // Notify parent component of items change
+        if (onItemsChange) {
+          onItemsChange(plannables);
+        }
+
         if (errors.plannables) {
           console.error('Failed to fetch plannables:', errors.plannables);
           showError('Failed to load plannable items');
@@ -90,7 +95,11 @@ const PlannablesList = ({ tripId }) => {
   const performDelete = async (itemId) => {
     try {
       await deletePlannable(itemId);
-      setPlannables(plannables.filter(item => item.id !== itemId));
+      const updatedPlannables = plannables.filter(item => item.id !== itemId);
+      setPlannables(updatedPlannables);
+      if (onItemsChange) {
+        onItemsChange(updatedPlannables);
+      }
       showSuccess('Item deleted successfully');
     } catch (err) {
       console.error('Error deleting item:', err);
@@ -104,19 +113,26 @@ const PlannablesList = ({ tripId }) => {
     try {
       const isEditing = !!editingItem;
       let savedItem;
+      let updatedPlannables;
 
       if (isEditing) {
         savedItem = await updatePlannable(editingItem.id, formData);
-        setPlannables(plannables.map(item =>
+        updatedPlannables = plannables.map(item =>
           item.id === editingItem.id ? savedItem : item
-        ));
+        );
+        setPlannables(updatedPlannables);
         showSuccess('Item updated successfully');
       } else {
         savedItem = await createPlannable(tripId, formData);
-        setPlannables([...plannables, savedItem]);
+        updatedPlannables = [...plannables, savedItem];
+        setPlannables(updatedPlannables);
         showSuccess('Item added successfully');
       }
 
+      if (onItemsChange) {
+        onItemsChange(updatedPlannables);
+      }
+
       setShowForm(false);
       setEditingItem(null);
     } catch (err) {
@@ -195,40 +211,6 @@ const PlannablesList = ({ tripId }) => {
             )}
           </div>
         </div>
-
-        {/* Calendar Slots Sections */}
-        {calendarSlots.map(slot => {
-          const items = plannedItemsBySlot[slot.id] || [];
-          const slotDate = new Date(slot.slot_date);
-          const dayName = slotDate.toLocaleDateString('en-US', { weekday: 'long' });
-          const dateStr = slotDate.toLocaleDateString('en-US', { month: 'short', day: 'numeric' });
-
-          return (
-            <div key={slot.id} className="plannables-section">
-              <h3 className="section-title">
-                📅 {slot.name}
-                <span className="section-date">{dayName}, {dateStr}</span>
-                {items.length > 0 && (
-                  <span className="item-count">{items.length}</span>
-                )}
-              </h3>
-              <div className="section-items">
-                {items.length === 0 ? (
-                  <p className="empty-message">No items planned for this day</p>
-                ) : (
-                  items.map(item => (
-                    <PlannableItem
-                      key={item.id}
-                      item={item}
-                      onEdit={handleEditItem}
-                      onDelete={handleDeleteItem}
-                    />
-                  ))
-                )}
-              </div>
-            </div>
-          );
-        })}
       </div>
 
       {showForm && (
diff --git a/frontend/src/components/timeline/DaySection.css b/frontend/src/components/timeline/DaySection.css
new file mode 100644
index 0000000..5f06c94
--- /dev/null
+++ b/frontend/src/components/timeline/DaySection.css
@@ -0,0 +1,32 @@
+.day-section {
+  background: var(--bg-card);
+  border: 1px solid var(--primary-color);
+  border-radius: var(--radius-lg);
+  padding: 1.5rem;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
+}
+
+.day-header {
+  margin-bottom: 1.5rem;
+  padding-bottom: 1rem;
+  border-bottom: 2px solid rgba(228, 93, 4, 0.2);
+}
+
+.day-header h4 {
+  font-size: 1.25rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin: 0 0 0.25rem 0;
+}
+
+.day-header p {
+  font-size: 0.9rem;
+  color: var(--text-secondary);
+  margin: 0;
+}
+
+.hours-grid {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
diff --git a/frontend/src/components/timeline/DaySection.jsx b/frontend/src/components/timeline/DaySection.jsx
new file mode 100644
index 0000000..162d863
--- /dev/null
+++ b/frontend/src/components/timeline/DaySection.jsx
@@ -0,0 +1,66 @@
+import { useMemo } from 'react';
+import HourRow from './HourRow';
+import './DaySection.css';
+
+const START_HOUR = 6;  // 6 AM
+const END_HOUR = 23;   // 11 PM
+
+function DaySection({ date, dayNumber, slots, plannableItems, onScheduleItem }) {
+  const dayName = date.toLocaleDateString('en-US', { weekday: 'long' });
+  const dateString = date.toLocaleDateString('en-US', {
+    month: 'short',
+    day: 'numeric',
+    year: 'numeric'
+  });
+
+
+  // Memoize slot-to-hour mapping to avoid recalculating on every render
+  const slotsByHour = useMemo(() => {
+    const mapping = {};
+
+    for (let hour = START_HOUR; hour <= END_HOUR; hour++) {
+      // Pre-compute hour boundaries once per hour (not per slot)
+      // Create hour boundaries explicitly to avoid DST issues
+      const hourStart = new Date(date.getFullYear(), date.getMonth(), date.getDate(), hour, 0, 0, 0);
+      const hourEnd = new Date(date.getFullYear(), date.getMonth(), date.getDate(), hour, 59, 59, 999);
+
+      mapping[hour] = slots.filter(slot => {
+        if (!slot.datetime_start) return false;
+
+        const slotStart = new Date(slot.datetime_start);
+        const slotEnd = new Date(slot.datetime_end);
+
+        // Check if slot overlaps with this hour (strict comparison)
+        return slotStart < hourEnd && slotEnd > hourStart;
+      });
+    }
+
+    return mapping;
+  }, [slots, date.getTime()]);
+
+  return (
+    <div className="day-section">
+      <div className="day-header">
+        <h4>
+          Day {dayNumber}: {dayName}
+        </h4>
+        <p>{dateString}</p>
+      </div>
+
+      <div className="hours-grid">
+        {Object.keys(slotsByHour).map(hour => (
+          <HourRow
+            key={hour}
+            hour={parseInt(hour)}
+            date={date}
+            slots={slotsByHour[hour]}
+            plannableItems={plannableItems}
+            onScheduleItem={onScheduleItem}
+          />
+        ))}
+      </div>
+    </div>
+  );
+}
+
+export default DaySection;
diff --git a/frontend/src/components/timeline/HourRow.css b/frontend/src/components/timeline/HourRow.css
new file mode 100644
index 0000000..7c9f780
--- /dev/null
+++ b/frontend/src/components/timeline/HourRow.css
@@ -0,0 +1,98 @@
+.hour-row {
+  display: flex;
+  align-items: stretch;
+  border-left: 2px solid var(--primary-color);
+  min-height: 60px;
+  transition: background-color 0.2s ease;
+  position: relative;
+}
+
+.hour-row:hover {
+  background-color: rgba(228, 93, 4, 0.03);
+}
+
+.hour-label {
+  width: 100px;
+  flex-shrink: 0;
+  padding: 0.75rem 1rem;
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: var(--text-secondary);
+}
+
+.hour-content {
+  flex: 1;
+  padding: 0.75rem 1rem;
+  position: relative;
+}
+
+.scheduled-slot {
+  background: rgba(59, 130, 246, 0.08);
+  border: 1px solid rgba(59, 130, 246, 0.3);
+  border-radius: var(--radius-md);
+  padding: 0.75rem;
+  margin-bottom: 0.5rem;
+}
+
+.scheduled-slot-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+}
+
+.scheduled-slot-content {
+  flex: 1;
+}
+
+.scheduled-slot-title {
+  font-weight: 600;
+  color: #1e40af;
+  margin: 0 0 0.25rem 0;
+  font-size: 0.95rem;
+}
+
+.scheduled-slot-time {
+  font-size: 0.85rem;
+  color: #1d4ed8;
+  margin-bottom: 0.25rem;
+}
+
+.scheduled-slot-items {
+  margin-top: 0.5rem;
+  font-size: 0.8rem;
+  color: #2563eb;
+}
+
+.add-button {
+  position: absolute;
+  right: 0.5rem;
+  top: 0.5rem;
+  padding: 0.375rem;
+  background-color: #22c55e;
+  color: white;
+  border: none;
+  border-radius: 50%;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  box-shadow: 0 2px 6px rgba(34, 197, 94, 0.3);
+  transition: all 0.2s ease;
+  opacity: 0;
+  width: 28px;
+  height: 28px;
+}
+
+.hour-row:hover .add-button {
+  opacity: 1;
+}
+
+.add-button:hover {
+  background-color: #16a34a;
+  transform: scale(1.1);
+}
+
+.add-button svg {
+  width: 16px;
+  height: 16px;
+}
diff --git a/frontend/src/components/timeline/HourRow.jsx b/frontend/src/components/timeline/HourRow.jsx
new file mode 100644
index 0000000..2c5edf4
--- /dev/null
+++ b/frontend/src/components/timeline/HourRow.jsx
@@ -0,0 +1,100 @@
+import { useState } from 'react';
+import { PlusIcon } from '@heroicons/react/24/outline';
+import ScheduleItemModal from './ScheduleItemModal';
+import './HourRow.css';
+
+function HourRow({ hour, date, slots, plannableItems, onScheduleItem }) {
+  const [showModal, setShowModal] = useState(false);
+
+  const formatHour = (h) => {
+    return `${h.toString().padStart(2, '0')}:00`;
+  };
+
+  const handleAddClick = () => {
+    setShowModal(true);
+  };
+
+  const handleSchedule = async (plannableItemId, startDatetime, endDatetime) => {
+    try {
+      await onScheduleItem(plannableItemId, startDatetime, endDatetime);
+      setShowModal(false);
+    } catch (error) {
+      // Error is already logged in parent, just rethrow to let modal handle it
+      throw error;
+    }
+  };
+
+  // Check if there's a slot that starts at this hour
+  const slotStartsHere = slots.find(slot => {
+    // Parse the datetime string and get the local hours
+    const slotStart = new Date(slot.datetime_start);
+    const startHour = slotStart.getHours();
+    return startHour === hour;
+  });
+
+  return (
+    <>
+      <div className="hour-row">
+        {/* Hour label */}
+        <div className="hour-label">
+          {formatHour(hour)}
+        </div>
+
+        {/* Content area */}
+        <div className="hour-content">
+          {/* Scheduled items that start at this hour */}
+          {slotStartsHere && (
+            <div className="scheduled-slot">
+              <div className="scheduled-slot-header">
+                <div className="scheduled-slot-content">
+                  <div className="scheduled-slot-title">
+                    {slotStartsHere.name}
+                  </div>
+                  <div className="scheduled-slot-time">
+                    {new Date(slotStartsHere.datetime_start).toLocaleTimeString('en-US', {
+                      hour: '2-digit',
+                      minute: '2-digit',
+                      hour12: false
+                    })}
+                    {' - '}
+                    {new Date(slotStartsHere.datetime_end).toLocaleTimeString('en-US', {
+                      hour: '2-digit',
+                      minute: '2-digit',
+                      hour12: false
+                    })}
+                  </div>
+                  {slotStartsHere.planned_items && slotStartsHere.planned_items.length > 0 && (
+                    <div className="scheduled-slot-items">
+                      {slotStartsHere.planned_items.map(pi => pi.plannable_item?.name).join(', ')}
+                    </div>
+                  )}
+                </div>
+              </div>
+            </div>
+          )}
+
+          {/* Add button - CSS-only hover */}
+          <button
+            onClick={handleAddClick}
+            className="add-button"
+            title="Schedule an item"
+          >
+            <PlusIcon />
+          </button>
+        </div>
+      </div>
+
+      {showModal && (
+        <ScheduleItemModal
+          date={date}
+          hour={hour}
+          plannableItems={plannableItems}
+          onSchedule={handleSchedule}
+          onClose={() => setShowModal(false)}
+        />
+      )}
+    </>
+  );
+}
+
+export default HourRow;
diff --git a/frontend/src/components/timeline/ScheduleItemModal.css b/frontend/src/components/timeline/ScheduleItemModal.css
new file mode 100644
index 0000000..594eca0
--- /dev/null
+++ b/frontend/src/components/timeline/ScheduleItemModal.css
@@ -0,0 +1,98 @@
+.schedule-form {
+  display: flex;
+  flex-direction: column;
+  gap: 1.5rem;
+}
+
+.schedule-form-error {
+  background-color: #fee;
+  border: 1px solid #fcc;
+  color: #c33;
+  padding: 0.75rem 1rem;
+  border-radius: var(--border-radius-md);
+  font-size: 0.9rem;
+}
+
+.schedule-form-group {
+  display: flex;
+  flex-direction: column;
+}
+
+.schedule-form-label {
+  display: block;
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: var(--color-text-primary);
+  margin-bottom: 0.5rem;
+}
+
+.schedule-form-select {
+  width: 100%;
+  padding: 0.75rem;
+  border: 1px solid var(--color-border);
+  border-radius: var(--border-radius-md);
+  font-size: 1rem;
+  background-color: var(--color-bg-primary);
+  color: var(--color-text-primary);
+  transition: border-color var(--transition-normal);
+}
+
+.schedule-form-select:focus {
+  outline: none;
+  border-color: var(--primary-color);
+  box-shadow: 0 0 0 3px rgba(228, 93, 4, 0.1);
+}
+
+.schedule-time-group {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 1rem;
+}
+
+.schedule-form-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 0.75rem;
+  padding-top: 1rem;
+  border-top: 1px solid var(--color-border-light);
+}
+
+.schedule-btn-cancel {
+  padding: 0.75rem 1.5rem;
+  color: var(--color-text-primary);
+  background-color: var(--color-bg-secondary);
+  border: none;
+  border-radius: var(--border-radius-md);
+  cursor: pointer;
+  font-weight: 500;
+  transition: background-color var(--transition-normal);
+}
+
+.schedule-btn-cancel:hover:not(:disabled) {
+  background-color: var(--color-border);
+}
+
+.schedule-btn-cancel:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.schedule-btn-submit {
+  padding: 0.75rem 1.5rem;
+  color: white;
+  background-color: var(--primary-color);
+  border: none;
+  border-radius: var(--border-radius-md);
+  cursor: pointer;
+  font-weight: 500;
+  transition: background-color var(--transition-normal);
+}
+
+.schedule-btn-submit:hover:not(:disabled) {
+  background-color: var(--primary-hover);
+}
+
+.schedule-btn-submit:disabled {
+  background-color: var(--color-border);
+  cursor: not-allowed;
+}
diff --git a/frontend/src/components/timeline/ScheduleItemModal.jsx b/frontend/src/components/timeline/ScheduleItemModal.jsx
new file mode 100644
index 0000000..15d2baf
--- /dev/null
+++ b/frontend/src/components/timeline/ScheduleItemModal.jsx
@@ -0,0 +1,159 @@
+import { useState, useEffect, useMemo } from 'react';
+import BaseModal from '../BaseModal';
+import './ScheduleItemModal.css';
+
+function ScheduleItemModal({ date, hour, plannableItems, onSchedule, onClose }) {
+  const [selectedItemId, setSelectedItemId] = useState('');
+  const [startTime, setStartTime] = useState('');
+  const [endTime, setEndTime] = useState('');
+  const [error, setError] = useState('');
+  const [submitting, setSubmitting] = useState(false);
+
+  useEffect(() => {
+    // Set default times based on the clicked hour
+    const startHour = hour.toString().padStart(2, '0');
+    const endHour = (hour + 1).toString().padStart(2, '0');
+    setStartTime(`${startHour}:00`);
+    setEndTime(`${endHour}:00`);
+  }, [hour]);
+
+  const handleSubmit = async (e) => {
+    e.preventDefault();
+    setError('');
+
+    if (!selectedItemId) {
+      setError('Please select an item to schedule');
+      return;
+    }
+
+    if (!startTime || !endTime) {
+      setError('Please select start and end times');
+      return;
+    }
+
+    // Construct full datetime strings using local date
+    const year = date.getFullYear();
+    const month = String(date.getMonth() + 1).padStart(2, '0');
+    const day = String(date.getDate()).padStart(2, '0');
+    const dateString = `${year}-${month}-${day}`;
+    const startDatetime = `${dateString} ${startTime}:00`;
+    const endDatetime = `${dateString} ${endTime}:00`;
+
+    // Validate end time is after start time
+    if (endTime <= startTime) {
+      setError('End time must be after start time');
+      return;
+    }
+
+    try {
+      setSubmitting(true);
+      await onSchedule(selectedItemId, startDatetime, endDatetime);
+      // Modal will be closed by parent (HourRow) on success
+    } catch (err) {
+      console.error('Error in modal submit:', err);
+      setError(err.response?.data?.message || err.message || 'Failed to schedule item');
+      setSubmitting(false);
+    }
+  };
+
+  // Generate time options (every 30 minutes) - memoized to avoid recreation
+  const timeOptions = useMemo(() => {
+    const options = [];
+    for (let h = 0; h < 24; h++) {
+      for (let m = 0; m < 60; m += 30) {
+        const timeStr = `${h.toString().padStart(2, '0')}:${m.toString().padStart(2, '0')}`;
+        options.push(timeStr);
+      }
+    }
+    return options;
+  }, []);
+
+  return (
+    <BaseModal isOpen={true} onClose={onClose} title="Schedule Item">
+      <form onSubmit={handleSubmit} className="schedule-form">
+        {error && (
+          <div className="schedule-form-error">
+            {error}
+          </div>
+        )}
+
+        <div className="schedule-form-group">
+          <label className="schedule-form-label">
+            Select Item
+          </label>
+          <select
+            value={selectedItemId}
+            onChange={(e) => setSelectedItemId(e.target.value)}
+            className="schedule-form-select"
+            required
+          >
+            <option value="">-- Choose an item --</option>
+            {plannableItems.map(item => (
+              <option key={item.id} value={item.id}>
+                {item.name} {item.type ? `(${item.type})` : ''}
+              </option>
+            ))}
+          </select>
+        </div>
+
+        <div className="schedule-time-group">
+          <div className="schedule-form-group">
+            <label className="schedule-form-label">
+              Start Time
+            </label>
+            <select
+              value={startTime}
+              onChange={(e) => setStartTime(e.target.value)}
+              className="schedule-form-select"
+              required
+            >
+              {timeOptions.map(time => (
+                <option key={time} value={time}>
+                  {time}
+                </option>
+              ))}
+            </select>
+          </div>
+
+          <div className="schedule-form-group">
+            <label className="schedule-form-label">
+              End Time
+            </label>
+            <select
+              value={endTime}
+              onChange={(e) => setEndTime(e.target.value)}
+              className="schedule-form-select"
+              required
+            >
+              {timeOptions.map(time => (
+                <option key={time} value={time}>
+                  {time}
+                </option>
+              ))}
+            </select>
+          </div>
+        </div>
+
+        <div className="schedule-form-actions">
+          <button
+            type="button"
+            onClick={onClose}
+            className="schedule-btn-cancel"
+            disabled={submitting}
+          >
+            Cancel
+          </button>
+          <button
+            type="submit"
+            className="schedule-btn-submit"
+            disabled={submitting}
+          >
+            {submitting ? 'Scheduling...' : 'Schedule'}
+          </button>
+        </div>
+      </form>
+    </BaseModal>
+  );
+}
+
+export default ScheduleItemModal;
diff --git a/frontend/src/components/timeline/TripTimeline.css b/frontend/src/components/timeline/TripTimeline.css
new file mode 100644
index 0000000..ea6f659
--- /dev/null
+++ b/frontend/src/components/timeline/TripTimeline.css
@@ -0,0 +1,24 @@
+.trip-timeline {
+  width: 100%;
+}
+
+.trip-timeline h3 {
+  font-size: 1.5rem;
+  font-weight: 600;
+  margin-bottom: 1.5rem;
+  color: var(--text-primary);
+  font-family: var(--font-secondary);
+}
+
+.timeline-days-container {
+  display: flex;
+  flex-direction: column;
+  gap: 2rem;
+}
+
+.timeline-loading {
+  padding: 2rem;
+  color: var(--text-muted);
+  text-align: center;
+  font-size: 1.1rem;
+}
diff --git a/frontend/src/components/timeline/TripTimeline.jsx b/frontend/src/components/timeline/TripTimeline.jsx
new file mode 100644
index 0000000..17f3e6a
--- /dev/null
+++ b/frontend/src/components/timeline/TripTimeline.jsx
@@ -0,0 +1,113 @@
+import { useState, useEffect } from 'react';
+import DaySection from './DaySection';
+import axios from 'axios';
+import './TripTimeline.css';
+
+const API_URL = import.meta.env.VITE_API_URL || 'http://localhost:8000';
+
+function TripTimeline({ trip, plannableItems, onScheduleSuccess }) {
+  const [calendarSlots, setCalendarSlots] = useState([]);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    fetchCalendarSlots();
+  }, [trip.id]);
+
+  const fetchCalendarSlots = async () => {
+    try {
+      const token = localStorage.getItem('token');
+      const response = await axios.get(`${API_URL}/api/trips/${trip.id}/calendar-slots`, {
+        headers: { Authorization: `Bearer ${token}` }
+      });
+      const slots = response.data.data || [];
+      setCalendarSlots(slots);
+    } catch (error) {
+      console.error('Error fetching calendar slots:', error);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  const handleScheduleItem = async (plannableItemId, startDatetime, endDatetime) => {
+    try {
+      const token = localStorage.getItem('token');
+      const payload = {
+        plannable_item_id: plannableItemId,
+        trip_id: trip.id,
+        start_datetime: startDatetime,
+        end_datetime: endDatetime,
+      };
+
+      const response = await axios.post(
+        `${API_URL}/api/planned-items`,
+        payload,
+        {
+          headers: { Authorization: `Bearer ${token}` }
+        }
+      );
+
+      await fetchCalendarSlots();
+      if (onScheduleSuccess) {
+        onScheduleSuccess();
+      }
+    } catch (error) {
+      console.error('Error scheduling item:', error);
+      console.error('Error response:', error.response?.data);
+      throw error;
+    }
+  };
+
+  const generateDays = () => {
+    const days = [];
+    const start = new Date(trip.start_date);
+    const end = new Date(trip.end_date);
+
+    for (let d = new Date(start); d <= end; ) {
+      days.push(new Date(d));
+      d.setDate(d.getDate() + 1);
+    }
+
+    return days;
+  };
+
+  const getSlotsForDay = (date) => {
+    // Format date as YYYY-MM-DD in local timezone, not UTC
+    const year = date.getFullYear();
+    const month = String(date.getMonth() + 1).padStart(2, '0');
+    const day = String(date.getDate()).padStart(2, '0');
+    const dateString = `${year}-${month}-${day}`;
+
+    const slots = calendarSlots.filter(slot => {
+      // slot_date comes as "2025-12-12T00:00:00.000000Z", extract just the date part
+      const slotDateString = slot.slot_date.split('T')[0];
+      return slotDateString === dateString;
+    });
+    return slots;
+  };
+
+  if (loading) {
+    return <div className="timeline-loading">Loading timeline...</div>;
+  }
+
+  const days = generateDays();
+
+  return (
+    <div className="trip-timeline">
+      <h3>Trip Timeline</h3>
+      <div className="timeline-days-container">
+        {days.map((day, index) => (
+          <DaySection
+            key={`${day.getFullYear()}-${day.getMonth()}-${day.getDate()}`}
+            date={day}
+            dayNumber={index + 1}
+            slots={getSlotsForDay(day)}
+            plannableItems={plannableItems}
+            onScheduleItem={handleScheduleItem}
+          />
+        ))}
+      </div>
+    </div>
+  );
+}
+
+export default TripTimeline;
diff --git a/tests/.gitignore b/tests/.gitignore
index 88ad741..fe5002e 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -5,3 +5,4 @@ screenshots/
 .env.local
 coverage/
 test-results/
+/.trees
diff --git a/tests/jest-local.json b/tests/jest-local.json
index fb834c5..c637b80 100644
--- a/tests/jest-local.json
+++ b/tests/jest-local.json
@@ -2,5 +2,5 @@
   "testEnvironment": "node",
   "testMatch": ["**/specs/**/*.test.js"],
   "setupFilesAfterEnv": ["<rootDir>/support/config/jest.setup.local.js"],
-  "testTimeout": 30000
+  "testTimeout": 60000
 }
\ No newline at end of file
diff --git a/tests/specs/integration/timeline-scheduling.test.js b/tests/specs/integration/timeline-scheduling.test.js
new file mode 100644
index 0000000..f65d4be
--- /dev/null
+++ b/tests/specs/integration/timeline-scheduling.test.js
@@ -0,0 +1,571 @@
+const { By, until } = require('selenium-webdriver');
+const RegistrationPage = require('../../support/pages/RegistrationPage');
+const LoginPage = require('../../support/pages/LoginPage');
+const DashboardPage = require('../../support/pages/DashboardPage');
+const TripPage = require('../../support/pages/TripPage');
+
+describe('Timeline Scheduling Feature Test', () => {
+  let driver;
+  let registrationPage;
+  let loginPage;
+  let dashboardPage;
+  let tripPage;
+  let testUser;
+  let testTrip;
+
+  beforeAll(async () => {
+    driver = await global.createDriver();
+    registrationPage = new RegistrationPage(driver);
+    loginPage = new LoginPage(driver);
+    dashboardPage = new DashboardPage(driver);
+    tripPage = new TripPage(driver);
+
+    // Create unique test data
+    const timestamp = Date.now();
+    testUser = {
+      name: `Timeline Test User ${timestamp}`,
+      email: `timeline.test.${timestamp}@example.com`,
+      password: 'TimelineTest123!'
+    };
+
+    testTrip = {
+      name: `Timeline Test Trip ${timestamp}`,
+      description: 'Testing timeline scheduling feature',
+      startDate: '2025-03-01',
+      endDate: '2025-03-03'
+    };
+  });
+
+  afterAll(async () => {
+    global.timelineTestsInitialized = false;
+    await global.quitDriver(driver);
+  });
+
+  beforeEach(async () => {
+    // For individual test runs or when starting fresh, ensure we have proper setup
+    if (!global.timelineTestsInitialized) {
+      // Clear storage and cookies
+      await Promise.all([
+        driver.manage().deleteAllCookies().catch(() => {}),
+        driver.executeScript('try { localStorage.clear(); sessionStorage.clear(); } catch(e) {}')
+      ]);
+
+      // Navigate to base URL
+      await driver.get(process.env.APP_URL || 'http://localhost:5173');
+      await driver.wait(until.urlContains('/'), 5000);
+
+      // Register new user
+      try {
+        await driver.wait(until.elementLocated(By.css('.auth-toggle button:last-child')), 2000);
+        await driver.findElement(By.css('.auth-toggle button:last-child')).click();
+
+        await registrationPage.register(testUser.name, testUser.email, testUser.password);
+
+        // Wait for dashboard to load
+        await driver.wait(until.elementLocated(By.className('dashboard')), 10000);
+        await driver.wait(until.elementLocated(By.css('.add-trip-card')), 10000);
+
+        // Create a trip
+        const addTripCard = await driver.findElement(By.css('.add-trip-card'));
+        await addTripCard.click();
+        await driver.wait(until.elementLocated(By.css('.trip-modal')), 10000);
+
+        await tripPage.fillTripForm(testTrip);
+        await tripPage.submitTripForm();
+
+        // Wait for trip to be created
+        await driver.wait(until.elementLocated(By.xpath(`//h3[contains(text(), "${testTrip.name}")]`)), 10000);
+
+        global.timelineTestsInitialized = true;
+      } catch (e) {
+        console.log('Failed to initialize timeline test environment:', e.message);
+      }
+    }
+  });
+
+  // Helper function to navigate to trip detail page
+  async function navigateToTripDetail() {
+    const currentUrl = await driver.getCurrentUrl();
+
+    if (global.timelineTripDetailUrl && currentUrl === global.timelineTripDetailUrl) {
+      await driver.wait(until.elementLocated(By.className('trip-timeline')), 10000);
+      await driver.sleep(500);
+      return;
+    }
+
+    if (global.timelineTripDetailUrl) {
+      await driver.get(global.timelineTripDetailUrl);
+      await driver.sleep(1000);
+    } else {
+      await driver.wait(until.elementLocated(By.className('dashboard')), 10000);
+      const tripCard = await driver.findElement(By.xpath(`//h3[contains(text(), "${testTrip.name}")]/ancestor::div[contains(@class, 'trip-card')]`));
+      await tripCard.click();
+      await driver.wait(until.urlContains('/trip/'), 10000);
+      global.timelineTripDetailUrl = await driver.getCurrentUrl();
+    }
+
+    await driver.wait(until.elementLocated(By.className('trip-timeline')), 10000);
+    await driver.sleep(500);
+  }
+
+  // Helper function to create a plannable item
+  async function createPlannableItem(itemData) {
+    // Ensure no modal is already open
+    await driver.sleep(500);
+
+    // Click Add Item button in sidebar using JavaScript click
+    const addItemButton = await driver.findElement(By.xpath('//button[contains(text(), "Add Item")]'));
+    await driver.executeScript("arguments[0].scrollIntoView(true);", addItemButton);
+    await driver.sleep(300);
+    await driver.executeScript("arguments[0].click();", addItemButton);
+
+    // Wait for form modal
+    await driver.wait(until.elementLocated(By.className('plannable-form-modal')), 5000);
+
+    // Fill in the form
+    await driver.findElement(By.name('name')).sendKeys(itemData.name);
+
+    if (itemData.type) {
+      const typeSelect = await driver.findElement(By.name('type'));
+      await typeSelect.findElement(By.xpath(`//option[@value="${itemData.type}"]`)).click();
+    }
+
+    if (itemData.address) {
+      await driver.findElement(By.name('address')).sendKeys(itemData.address);
+    }
+
+    if (itemData.notes) {
+      await driver.findElement(By.name('notes')).sendKeys(itemData.notes);
+    }
+
+    // Submit without assigning to a slot (leave in "Unplanned Items")
+    const submitButton = await driver.findElement(By.xpath('//button[contains(text(), "Add Item")]'));
+    await driver.executeScript("arguments[0].scrollIntoView(true);", submitButton);
+    await driver.sleep(500);
+    await driver.executeScript("arguments[0].click();", submitButton);
+
+    // Wait for modal to close
+    await driver.sleep(1500);
+    await driver.wait(async () => {
+      const overlays = await driver.findElements(By.css('.plannable-form-overlay, .plannable-form-modal'));
+      for (const overlay of overlays) {
+        try {
+          if (await overlay.isDisplayed()) {
+            return false;
+          }
+        } catch (e) {
+          // Stale element
+        }
+      }
+      return true;
+    }, 10000);
+
+    // Additional wait to ensure UI is stable
+    await driver.sleep(500);
+  }
+
+  // Helper to wait for modal close
+  async function waitForModalClose() {
+    await driver.sleep(1000);
+    await driver.wait(async () => {
+      const modals = await driver.findElements(By.css('.modal, .base-modal'));
+      for (const modal of modals) {
+        try {
+          if (await modal.isDisplayed()) {
+            return false;
+          }
+        } catch (e) {
+          // Stale element
+        }
+      }
+      return true;
+    }, 10000);
+  }
+
+  describe('Timeline Display', () => {
+    it('should display timeline with correct structure', async () => {
+      await navigateToTripDetail();
+
+      // Verify timeline container exists
+      const timeline = await driver.findElement(By.className('trip-timeline'));
+      expect(await timeline.isDisplayed()).toBe(true);
+
+      // Verify timeline has header
+      const timelineHeader = await driver.findElement(By.xpath('//h3[contains(text(), "Trip Timeline")]'));
+      expect(await timelineHeader.isDisplayed()).toBe(true);
+    });
+
+    it('should display all days of the trip', async () => {
+      await navigateToTripDetail();
+
+      // Trip is from March 1-3, so we should have 3 day sections
+      const daySections = await driver.findElements(By.className('day-section'));
+      expect(daySections.length).toBe(3);
+
+      // Verify day headers
+      const day1Header = await driver.findElement(By.xpath('//h4[contains(text(), "Day 1")]'));
+      expect(await day1Header.isDisplayed()).toBe(true);
+
+      const day2Header = await driver.findElement(By.xpath('//h4[contains(text(), "Day 2")]'));
+      expect(await day2Header.isDisplayed()).toBe(true);
+
+      const day3Header = await driver.findElement(By.xpath('//h4[contains(text(), "Day 3")]'));
+      expect(await day3Header.isDisplayed()).toBe(true);
+    });
+
+    it('should display hour rows for each day', async () => {
+      await navigateToTripDetail();
+
+      // Get first day section
+      const firstDaySection = await driver.findElement(By.className('day-section'));
+
+      // Should have hour rows (06:00 to 23:00 = 18 hours)
+      const hourRows = await firstDaySection.findElements(By.className('hour-row'));
+      expect(hourRows.length).toBeGreaterThanOrEqual(18);
+
+      // Verify specific hour labels exist
+      const hour6am = await driver.findElement(By.xpath('//div[contains(@class, "hour-label") and contains(text(), "06:00")]'));
+      expect(await hour6am.isDisplayed()).toBe(true);
+
+      const hour11pm = await driver.findElement(By.xpath('//div[contains(@class, "hour-label") and contains(text(), "23:00")]'));
+      expect(await hour11pm.isDisplayed()).toBe(true);
+    });
+  });
+
+  describe('Scheduling Items via Timeline', () => {
+    it('should show + button on hover over hour row', async () => {
+      await navigateToTripDetail();
+
+      // Find an hour row
+      const hourRow = await driver.findElement(By.className('hour-row'));
+
+      // Hover over it
+      await driver.actions().move({ origin: hourRow }).perform();
+      await driver.sleep(500);
+
+      // Should see a + button
+      const addButton = await hourRow.findElement(By.css('button'));
+      expect(await addButton.isDisplayed()).toBe(true);
+    });
+
+    it('should open schedule modal when clicking + button', async () => {
+      await navigateToTripDetail();
+
+      // First create a plannable item to schedule
+      await createPlannableItem({
+        name: 'Breakfast at Cafe',
+        type: 'restaurant',
+        notes: 'Morning coffee'
+      });
+
+      // Now find the 08:00 hour row
+      const hour8am = await driver.findElement(By.xpath('//div[contains(@class, "hour-label") and contains(text(), "08:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+
+      // Hover to show + button
+      await driver.actions().move({ origin: hour8am }).perform();
+      await driver.sleep(500);
+
+      // Click the + button
+      const addButton = await hour8am.findElement(By.css('button'));
+      await addButton.click();
+
+      // Wait for schedule modal to appear
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+
+      // Verify modal elements
+      const itemSelect = await driver.findElement(By.css('select'));
+      expect(await itemSelect.isDisplayed()).toBe(true);
+
+      // Should have time pickers
+      const timeInputs = await driver.findElements(By.css('select'));
+      expect(timeInputs.length).toBeGreaterThanOrEqual(2); // Start time and end time
+    });
+
+    it('should schedule an item at specific time', async () => {
+      await navigateToTripDetail();
+
+      // Create plannable item
+      await createPlannableItem({
+        name: 'Louvre Museum Visit',
+        type: 'attraction',
+        notes: 'Morning visit to see Mona Lisa'
+      });
+
+      await driver.sleep(1000);
+
+      // Find the 10:00 hour row on Day 1
+      const daySections = await driver.findElements(By.className('day-section'));
+      const day1Section = daySections[0];
+
+      const hour10am = await day1Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "10:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+
+      // Hover and click +
+      await driver.actions().move({ origin: hour10am }).perform();
+      await driver.sleep(500);
+
+      const addButton = await hour10am.findElement(By.css('button'));
+      await addButton.click();
+
+      // Wait for modal
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+
+      // Select the item
+      const itemSelect = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect.findElement(By.xpath('//option[contains(text(), "Louvre Museum Visit")]')).click();
+
+      // Start time should default to 10:00
+      const startTimeSelect = await driver.findElement(By.xpath('//label[contains(text(), "Start Time")]/following-sibling::select'));
+      const startTimeValue = await startTimeSelect.getAttribute('value');
+      expect(startTimeValue).toBe('10:00');
+
+      // Set end time to 12:00
+      const endTimeSelect = await driver.findElement(By.xpath('//label[contains(text(), "End Time")]/following-sibling::select'));
+      await endTimeSelect.findElement(By.xpath('//option[@value="12:00"]')).click();
+
+      // Submit
+      const scheduleButton = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton.click();
+
+      // Wait for modal to close
+      await waitForModalClose();
+
+      // Verify item appears in timeline at 10:00
+      await driver.sleep(1000);
+      const scheduledItem = await driver.findElement(By.xpath('//div[contains(@class, "scheduled-slot") and contains(., "Louvre Museum Visit")]'));
+      expect(await scheduledItem.isDisplayed()).toBe(true);
+
+      // Verify time display shows 10:00 - 12:00
+      const timeDisplay = await scheduledItem.getText();
+      expect(timeDisplay).toContain('10:00');
+      expect(timeDisplay).toContain('12:00');
+    });
+
+    it('should schedule multiple items on the same day', async () => {
+      await navigateToTripDetail();
+
+      // Create multiple plannable items
+      await createPlannableItem({
+        name: 'Morning Croissant',
+        type: 'restaurant'
+      });
+
+      await driver.sleep(500);
+
+      await createPlannableItem({
+        name: 'Afternoon Tea',
+        type: 'restaurant'
+      });
+
+      await driver.sleep(1000);
+
+      // Schedule first item at 08:00
+      const daySections = await driver.findElements(By.className('day-section'));
+      const day2Section = daySections[1]; // Day 2
+
+      const hour8am = await day2Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "08:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+
+      await driver.actions().move({ origin: hour8am }).perform();
+      await driver.sleep(500);
+      await hour8am.findElement(By.css('button')).click();
+
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+
+      const itemSelect1 = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect1.findElement(By.xpath('//option[contains(text(), "Morning Croissant")]')).click();
+
+      const scheduleButton1 = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton1.click();
+      await waitForModalClose();
+
+      await driver.sleep(1000);
+
+      // Schedule second item at 15:00
+      const hour3pm = await day2Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "15:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+
+      await driver.actions().move({ origin: hour3pm }).perform();
+      await driver.sleep(500);
+      await hour3pm.findElement(By.css('button')).click();
+
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+
+      const itemSelect2 = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect2.findElement(By.xpath('//option[contains(text(), "Afternoon Tea")]')).click();
+
+      const endTimeSelect = await driver.findElement(By.xpath('//label[contains(text(), "End Time")]/following-sibling::select'));
+      await endTimeSelect.findElement(By.xpath('//option[@value="16:00"]')).click();
+
+      const scheduleButton2 = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton2.click();
+      await waitForModalClose();
+
+      await driver.sleep(1000);
+
+      // Verify both items appear in Day 2 section
+      const croissantItem = await day2Section.findElement(By.xpath('.//div[contains(., "Morning Croissant")]'));
+      expect(await croissantItem.isDisplayed()).toBe(true);
+
+      const teaItem = await day2Section.findElement(By.xpath('.//div[contains(., "Afternoon Tea")]'));
+      expect(await teaItem.isDisplayed()).toBe(true);
+    });
+
+    it('should validate end time is after start time', async () => {
+      await navigateToTripDetail();
+
+      // Create plannable item
+      await createPlannableItem({
+        name: 'Invalid Time Test',
+        type: 'other'
+      });
+
+      await driver.sleep(1000);
+
+      // Open schedule modal at 14:00
+      const daySections = await driver.findElements(By.className('day-section'));
+      const day3Section = daySections[2]; // Day 3
+
+      const hour2pm = await day3Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "14:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+
+      await driver.actions().move({ origin: hour2pm }).perform();
+      await driver.sleep(500);
+      await hour2pm.findElement(By.css('button')).click();
+
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+
+      // Select item
+      const itemSelect = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect.findElement(By.xpath('//option[contains(text(), "Invalid Time Test")]')).click();
+
+      // Try to set end time before start time (e.g., start 14:00, end 13:00)
+      const endTimeSelect = await driver.findElement(By.xpath('//label[contains(text(), "End Time")]/following-sibling::select'));
+      await endTimeSelect.findElement(By.xpath('//option[@value="13:00"]')).click();
+
+      // Submit
+      const scheduleButton = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton.click();
+
+      await driver.sleep(1000);
+
+      // Should show error message
+      const errorMessage = await driver.findElement(By.xpath('//*[contains(text(), "End time must be after start time")]'));
+      expect(await errorMessage.isDisplayed()).toBe(true);
+    });
+  });
+
+  describe('Timeline Integration', () => {
+    it('should display item in both sidebar and timeline after scheduling', async () => {
+      await navigateToTripDetail();
+
+      // Create plannable item
+      await createPlannableItem({
+        name: 'Arc de Triomphe',
+        type: 'attraction'
+      });
+
+      await driver.sleep(1000);
+
+      // Verify it appears in sidebar under "Unplanned Items"
+      const sidebarItem = await driver.findElement(By.xpath('//h4[contains(text(), "Arc de Triomphe")]'));
+      expect(await sidebarItem.isDisplayed()).toBe(true);
+
+      // Schedule it via timeline
+      const daySections = await driver.findElements(By.className('day-section'));
+      const day1Section = daySections[0];
+
+      const hour11am = await day1Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "11:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+
+      await driver.actions().move({ origin: hour11am }).perform();
+      await driver.sleep(500);
+      await hour11am.findElement(By.css('button')).click();
+
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+
+      const itemSelect = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect.findElement(By.xpath('//option[contains(text(), "Arc de Triomphe")]')).click();
+
+      const scheduleButton = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton.click();
+      await waitForModalClose();
+
+      await driver.sleep(1000);
+
+      // Verify it now appears in timeline
+      const timelineItem = await driver.findElement(By.xpath('//div[contains(@class, "scheduled-slot") and contains(., "Arc de Triomphe")]'));
+      expect(await timelineItem.isDisplayed()).toBe(true);
+
+      // Note: The sidebar behavior might change - item could stay in unplanned or move to a day section
+      // For now, we just verify it's in the timeline
+    });
+
+    it('should maintain chronological order when items are scheduled out of order', async () => {
+      await navigateToTripDetail();
+
+      // Create items
+      await createPlannableItem({ name: 'Dinner', type: 'restaurant' });
+      await driver.sleep(500);
+      await createPlannableItem({ name: 'Breakfast', type: 'restaurant' });
+      await driver.sleep(500);
+      await createPlannableItem({ name: 'Lunch', type: 'restaurant' });
+      await driver.sleep(1000);
+
+      const daySections = await driver.findElements(By.className('day-section'));
+      const day1Section = daySections[0];
+
+      // Schedule Dinner first (19:00)
+      const hour7pm = await day1Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "19:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+      await driver.actions().move({ origin: hour7pm }).perform();
+      await driver.sleep(500);
+      await hour7pm.findElement(By.css('button')).click();
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+      let itemSelect = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect.findElement(By.xpath('//option[contains(text(), "Dinner")]')).click();
+      let scheduleButton = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton.click();
+      await waitForModalClose();
+      await driver.sleep(1000);
+
+      // Schedule Breakfast (07:00)
+      const hour7am = await day1Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "07:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+      await driver.actions().move({ origin: hour7am }).perform();
+      await driver.sleep(500);
+      await hour7am.findElement(By.css('button')).click();
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+      itemSelect = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect.findElement(By.xpath('//option[contains(text(), "Breakfast")]')).click();
+      scheduleButton = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton.click();
+      await waitForModalClose();
+      await driver.sleep(1000);
+
+      // Schedule Lunch (12:00)
+      const hour12pm = await day1Section.findElement(By.xpath('.//div[contains(@class, "hour-label") and contains(text(), "12:00")]/following-sibling::div[contains(@class, "hour-content")]'));
+      await driver.actions().move({ origin: hour12pm }).perform();
+      await driver.sleep(500);
+      await hour12pm.findElement(By.css('button')).click();
+      await driver.wait(until.elementLocated(By.xpath('//*[contains(text(), "Schedule Item")]')), 5000);
+      itemSelect = await driver.findElement(By.xpath('//label[contains(text(), "Select Item")]/following-sibling::select'));
+      await itemSelect.findElement(By.xpath('//option[contains(text(), "Lunch")]')).click();
+      scheduleButton = await driver.findElement(By.xpath('//button[contains(text(), "Schedule")]'));
+      await scheduleButton.click();
+      await waitForModalClose();
+      await driver.sleep(1000);
+
+      // Verify items appear in chronological order in Day 1 section
+      const scheduledSlots = await day1Section.findElements(By.className('scheduled-slot'));
+
+      // Get text of all scheduled items to verify order
+      const itemTexts = [];
+      for (const slot of scheduledSlots) {
+        const text = await slot.getText();
+        itemTexts.push(text);
+      }
+
+      // Breakfast should appear before Lunch, and Lunch before Dinner
+      const breakfastIndex = itemTexts.findIndex(text => text.includes('Breakfast'));
+      const lunchIndex = itemTexts.findIndex(text => text.includes('Lunch'));
+      const dinnerIndex = itemTexts.findIndex(text => text.includes('Dinner'));
+
+      expect(breakfastIndex).toBeLessThan(lunchIndex);
+      expect(lunchIndex).toBeLessThan(dinnerIndex);
+    });
+  });
+});