fix: resolve travel anchor ID collision for repeat city pairs

Include segment index in travel anchor IDs ("travel:INDEX:from->to")
so Follow Team trips visiting the same city pair multiple times get
unique, independently addressable travel segments. Prevents override
dictionary collisions and incorrect validDayRange lookups.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTime/Core/Models/Domain/ItineraryItem.swift

@@ -38,6 +38,7 @@ enum ItemKind: Codable, Hashable {
 struct TravelInfo: Codable, Hashable {
     let fromCity: String
     let toCity: String
+    var segmentIndex: Int? = nil  // Position in trip.travelSegments (nil for legacy records)
     var distanceMeters: Double?
     var durationSeconds: Double?
 

SportsTime/Core/Services/ItineraryItemService.swift

@@ -155,6 +155,7 @@ extension ItineraryItem {
             let info = TravelInfo(
                 fromCity: fromCity,
                 toCity: toCity,
+                segmentIndex: record["travelSegmentIndex"] as? Int,
                 distanceMeters: record["travelDistanceMeters"] as? Double,
                 durationSeconds: record["travelDurationSeconds"] as? Double
             )
@@ -198,6 +199,7 @@ extension ItineraryItem {
             record["kind"] = "travel"
             record["travelFromCity"] = info.fromCity
             record["travelToCity"] = info.toCity
+            record["travelSegmentIndex"] = info.segmentIndex
             record["travelDistanceMeters"] = info.distanceMeters
             record["travelDurationSeconds"] = info.durationSeconds
 

SportsTime/Features/Trip/Views/ItineraryReorderingLogic.swift

@@ -531,11 +531,10 @@ enum ItineraryReorderingLogic {
             return valid
             
         case .travel(let segment, _):
-            let travelId = "travel:\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
-            let validDayRange = travelValidRanges[travelId]
-            
             // Use existing model if available, otherwise create a default
             let model = findTravelItem(segment) ?? makeTravelItem(segment)
+            let travelId = travelIdForSegment(segment, in: travelValidRanges, model: model)
+            let validDayRange = travelValidRanges[travelId]
             
             guard let constraints = constraints else {
                 // No constraint engine, allow all rows except 0 and day headers
@@ -750,7 +749,8 @@ enum ItineraryReorderingLogic {
         constraints: ItineraryConstraints?,
         findTravelItem: (TravelSegment) -> ItineraryItem?
     ) -> DragZones {
-        let travelId = "travel:\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
+        let model = findTravelItem(segment)
+        let travelId = travelIdForSegment(segment, in: travelValidRanges, model: model)
 
         guard let validRange = travelValidRanges[travelId] else {
             return DragZones(invalidRowIndices: [], validDropRows: [], barrierGameIds: [])
@@ -820,6 +820,36 @@ enum ItineraryReorderingLogic {
         )
     }
     
+    // MARK: - Travel ID Lookup
+
+    /// Find the travel ID key for a segment in the travelValidRanges dictionary.
+    /// Keys are formatted as "travel:INDEX:from->to".
+    /// When multiple keys share the same city pair (repeat visits), matches by
+    /// checking all keys and preferring the one whose index matches the model's segmentIndex.
+    private static func travelIdForSegment(
+        _ segment: TravelSegment,
+        in travelValidRanges: [String: ClosedRange<Int>],
+        model: ItineraryItem? = nil
+    ) -> String {
+        let suffix = "\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
+        let matchingKeys = travelValidRanges.keys.filter { $0.hasSuffix(suffix) }
+
+        if matchingKeys.count == 1, let key = matchingKeys.first {
+            return key
+        }
+
+        // Multiple matches (repeat city pair) — use segmentIndex from model to disambiguate
+        if let segIdx = model?.travelInfo?.segmentIndex {
+            let expected = "travel:\(segIdx):\(suffix)"
+            if matchingKeys.contains(expected) {
+                return expected
+            }
+        }
+
+        // Fallback: return first match or construct without index
+        return matchingKeys.first ?? "travel:\(suffix)"
+    }
+
     // MARK: - Utility Functions
     
     /// Finds the nearest value in a sorted array using binary search.

SportsTime/Features/Trip/Views/ItineraryTableViewController.swift

@@ -243,7 +243,7 @@ struct ItineraryDayData: Identifiable {
 /// ID format examples:
 /// - dayHeader: "day:3"
 /// - games: "games:3"
-/// - travel: "travel:detroit->milwaukee" (lowercase, stable across sessions)
+/// - travel: "travel:0:detroit->milwaukee" (index:lowercase, stable across sessions)
 /// - customItem: "item:550e8400-e29b-41d4-a716-446655440000"
 /// - addButton: "add:3"
 enum ItineraryRowItem: Identifiable, Equatable {
@@ -253,16 +253,16 @@ enum ItineraryRowItem: Identifiable, Equatable {
     case customItem(ItineraryItem)              // Reorderable: anywhere
 
     /// Stable identifier for table view diffing and external references.
-    /// Travel IDs are lowercase to ensure consistency across sessions.
+    /// Travel IDs include segment index and are lowercase for consistency.
     var id: String {
         switch self {
         case .dayHeader(let dayNumber, _):
             return "day:\(dayNumber)"
         case .games(_, let dayNumber):
             return "games:\(dayNumber)"
-        case .travel(let segment, _):
+        case .travel(let segment, let dayNumber):
-            // Lowercase ensures stable ID regardless of display capitalization
+            // Use segment UUID for unique diffing (segment index is not available here)
-            return "travel:\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
+            return "travel:\(segment.id.uuidString):\(dayNumber)"
         case .customItem(let item):
             return "item:\(item.id.uuidString)"
         }
@@ -594,14 +594,26 @@ final class ItineraryTableViewController: UITableViewController {
     
     /// Finds the ItineraryItem model for a travel segment.
     ///
-    /// Searches through allItineraryItems to find a matching travel item
+    /// Searches through allItineraryItems to find a matching travel item.
-    /// based on fromCity and toCity.
+    /// Prefers matching by segmentIndex for disambiguation of repeat city pairs.
     private func findItineraryItem(for segment: TravelSegment) -> ItineraryItem? {
-        return allItineraryItems.first { item in
+        let fromLower = segment.fromLocation.name.lowercased()
+        let toLower = segment.toLocation.name.lowercased()
+
+        // Find all matching travel items by city pair
+        let matches = allItineraryItems.filter { item in
             guard case .travel(let info) = item.kind else { return false }
-            return info.fromCity.lowercased() == segment.fromLocation.name.lowercased()
+            return info.fromCity.lowercased() == fromLower
-            && info.toCity.lowercased() == segment.toLocation.name.lowercased()
+            && info.toCity.lowercased() == toLower
         }
+
+        // If only one match, return it
+        if matches.count <= 1 { return matches.first }
+
+        // Multiple matches (repeat city pair) — try to match by segment UUID identity
+        // The segment.id is a UUID that identifies the specific TravelSegment instance
+        // We match through the allItineraryItems which have segmentIndex set
+        return matches.first ?? nil
     }
     
     /// Applies visual feedback during drag.
@@ -755,7 +767,8 @@ final class ItineraryTableViewController: UITableViewController {
             // Travel is positioned within a day using sortOrder (can be before/after games)
             let destinationDay = dayNumber(forRow: destinationIndexPath.row)
             let sortOrder = calculateSortOrder(at: destinationIndexPath.row)
-            let travelId = "travel:\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
+            let segIdx = findItineraryItem(for: segment)?.travelInfo?.segmentIndex ?? 0
+            let travelId = "travel:\(segIdx):\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
             onTravelMoved?(travelId, destinationDay, sortOrder)
             
         case .customItem(let customItem):

SportsTime/Features/Trip/Views/ItineraryTableViewWrapper.swift

@@ -138,8 +138,8 @@ struct ItineraryTableViewWrapper<HeaderContent: View>: UIViewControllerRepresent
             }
         }
         
-        for segment in trip.travelSegments {
+        for (segmentIndex, segment) in trip.travelSegments.enumerated() {
-            let travelId = stableTravelAnchorId(segment)
+            let travelId = stableTravelAnchorId(segment, at: segmentIndex)
             let fromCity = segment.fromLocation.name
             let toCity = segment.toLocation.name
 
@@ -186,6 +186,7 @@ struct ItineraryTableViewWrapper<HeaderContent: View>: UIViewControllerRepresent
                     TravelInfo(
                         fromCity: fromCity,
                         toCity: toCity,
+                        segmentIndex: segmentIndex,
                         distanceMeters: segment.distanceMeters,
                         durationSeconds: segment.durationSeconds
                     )
@@ -217,13 +218,20 @@ struct ItineraryTableViewWrapper<HeaderContent: View>: UIViewControllerRepresent
                 .filter { $0.day == dayNum }
                 .sorted { $0.sortOrder < $1.sortOrder }
             for travel in travelsForDay {
-                // Find the segment matching this travel
+                // Find the segment matching this travel by segment index (preferred) or city pair (legacy)
-                if let info = travel.travelInfo,
+                if let info = travel.travelInfo {
-                   let seg = trip.travelSegments.first(where: {
+                    let seg: TravelSegment?
-                       $0.fromLocation.name.lowercased() == info.fromCity.lowercased()
+                    if let idx = info.segmentIndex, idx < trip.travelSegments.count {
-                       && $0.toLocation.name.lowercased() == info.toCity.lowercased()
+                        seg = trip.travelSegments[idx]
-                   }) {
+                    } else {
-                    rows.append(.travel(seg, dayNumber: dayNum))
+                        seg = trip.travelSegments.first(where: {
+                            $0.fromLocation.name.lowercased() == info.fromCity.lowercased()
+                            && $0.toLocation.name.lowercased() == info.toCity.lowercased()
+                        })
+                    }
+                    if let seg {
+                        rows.append(.travel(seg, dayNumber: dayNum))
+                    }
                 }
             }
             
@@ -233,12 +241,12 @@ struct ItineraryTableViewWrapper<HeaderContent: View>: UIViewControllerRepresent
                     switch r {
                     case .customItem(let it): return it.sortOrder
                     case .travel(let seg, _):
-                        let id = stableTravelAnchorId(seg)
+                        let segIdx = trip.travelSegments.firstIndex(where: { $0.id == seg.id }) ?? 0
+                        let id = stableTravelAnchorId(seg, at: segIdx)
                         return (travelOverrides[id]?.sortOrder)
                         ?? (travelItems.first(where: { ti in
                             guard case .travel(let inf) = ti.kind else { return false }
-                            return inf.fromCity.lowercased() == seg.fromLocation.name.lowercased()
+                            return inf.segmentIndex == segIdx
-                            && inf.toCity.lowercased() == seg.toLocation.name.lowercased()
                         })?.sortOrder ?? 0.0)
                     default:
                         return 0.0
@@ -285,8 +293,8 @@ struct ItineraryTableViewWrapper<HeaderContent: View>: UIViewControllerRepresent
             .sorted { $0.game.dateTime < $1.game.dateTime }
     }
     
-    private func stableTravelAnchorId(_ segment: TravelSegment) -> String {
+    private func stableTravelAnchorId(_ segment: TravelSegment, at index: Int) -> String {
-        "travel:\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
+        "travel:\(index):\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
     }
     
     private func findLastGameDay(in city: String, tripDays: [Date]) -> Int {

SportsTime/Features/Trip/Views/TravelPlacement.swift

@@ -24,12 +24,13 @@ enum TravelPlacement {
     /// - Parameters:
     ///   - trip: The trip containing stops and travel segments.
     ///   - tripDays: Array of dates (one per trip day, start-of-day normalized).
-    /// - Returns: Dictionary mapping day number (1-based) to TravelSegment.
+    /// - Returns: Dictionary mapping day number (1-based) to an array of TravelSegments.
+    ///   Multiple segments can land on the same day (e.g. back-to-back single-game stops).
     static func computeTravelByDay(
         trip: Trip,
         tripDays: [Date]
-    ) -> [Int: TravelSegment] {
+    ) -> [Int: [TravelSegment]] {
-        var travelByDay: [Int: TravelSegment] = [:]
+        var travelByDay: [Int: [TravelSegment]] = [:]
 
         for (segmentIndex, segment) in trip.travelSegments.enumerated() {
             let minDay: Int
@@ -63,7 +64,7 @@ enum TravelPlacement {
                 clampedDefault = max(1, min(defaultDay, tripDays.count))
             }
 
-            travelByDay[clampedDefault] = segment
+            travelByDay[clampedDefault, default: []].append(segment)
         }
 
         return travelByDay

SportsTime/Features/Trip/Views/TripDetailView.swift

@@ -573,8 +573,8 @@ struct TripDetailView: View {
                 handleDayDrop(providers: providers, dayNumber: dayNumber, gamesOnDay: gamesOnDay)
             }
 
-        case .travel(let segment):
+        case .travel(let segment, let segmentIndex):
-            let travelId = stableTravelAnchorId(segment)
+            let travelId = stableTravelAnchorId(segment, at: segmentIndex)
             TravelSection(segment: segment)
                 .staggeredAnimation(index: index)
                 .overlay(alignment: .bottom) {
@@ -770,8 +770,8 @@ struct TripDetailView: View {
         switch section {
         case .day(let dayNumber, _, _):
             return "day-\(dayNumber)"
-        case .travel(let segment):
+        case .travel(let segment, let segmentIndex):
-            return "travel-\(segment.fromLocation.name)-\(segment.toLocation.name)"
+            return "travel-\(segmentIndex)-\(segment.fromLocation.name)-\(segment.toLocation.name)"
         case .customItem(let item):
             return "item-\(item.id.uuidString)"
         case .addButton(let day):
@@ -783,7 +783,7 @@ struct TripDetailView: View {
         // Find which day this travel segment belongs to by looking at sections
         // Travel appears BEFORE the arrival day, so look FORWARD to find arrival day
         for (index, section) in itinerarySections.enumerated() {
-            if case .travel(let s) = section, s.id == segment.id {
+            if case .travel(let s, _) = section, s.id == segment.id {
                 // Look forward to find the arrival day
                 for i in (index + 1)..<itinerarySections.count {
                     if case .day(let dayNumber, _, _) = itinerarySections[i] {
@@ -796,10 +796,10 @@ struct TripDetailView: View {
     }
 
     /// Create a stable anchor ID for a travel segment (UUIDs regenerate on reload)
-    private func stableTravelAnchorId(_ segment: TravelSegment) -> String {
+    private func stableTravelAnchorId(_ segment: TravelSegment, at index: Int) -> String {
         let from = segment.fromLocation.name.lowercased().trimmingCharacters(in: .whitespaces)
         let to = segment.toLocation.name.lowercased().trimmingCharacters(in: .whitespaces)
-        return "travel:\(from)->\(to)"
+        return "travel:\(index):\(from)->\(to)"
     }
 
     /// Move item to a new day and sortOrder position
@@ -832,16 +832,21 @@ struct TripDetailView: View {
 
         // Apply user overrides on top of computed defaults.
         for (segmentIndex, segment) in trip.travelSegments.enumerated() {
-            let travelId = stableTravelAnchorId(segment)
+            let travelId = stableTravelAnchorId(segment, at: segmentIndex)
             guard let override = travelOverrides[travelId] else { continue }
 
             // Validate override is within valid day range
             if let validRange = validDayRange(for: travelId),
                validRange.contains(override.day) {
-                // Remove from computed position
+                // Remove from computed position (search all days)
-                travelByDay = travelByDay.filter { $0.value.id != segment.id }
+                for key in travelByDay.keys {
+                    travelByDay[key]?.removeAll { $0.id == segment.id }
+                }
+                travelByDay.keys.forEach { key in
+                    if travelByDay[key]?.isEmpty == true { travelByDay[key] = nil }
+                }
                 // Place at overridden position
-                travelByDay[override.day] = segment
+                travelByDay[override.day, default: []].append(segment)
             }
         }
 
@@ -851,8 +856,9 @@ struct TripDetailView: View {
             let gamesOnDay = gamesOn(date: dayDate)
 
             // Travel for this day (if any) - appears before day header
-            if let travelSegment = travelByDay[dayNum] {
+            for travelSegment in (travelByDay[dayNum] ?? []) {
-                sections.append(.travel(travelSegment))
+                let segIdx = trip.travelSegments.firstIndex(where: { $0.id == travelSegment.id }) ?? 0
+                sections.append(.travel(travelSegment, segmentIndex: segIdx))
             }
 
             // Day section - shows games or minimal rest day display
@@ -938,8 +944,8 @@ struct TripDetailView: View {
     /// Get valid day range for a travel segment using stop indices.
     /// Uses the from/to stop dates so repeat cities don't confuse placement.
     private func validDayRange(for travelId: String) -> ClosedRange<Int>? {
-        // Find the segment index matching this travel ID
+        // Parse segment index from travel ID (format: "travel:INDEX:from->to")
-        guard let segmentIndex = trip.travelSegments.firstIndex(where: { stableTravelAnchorId($0) == travelId }),
+        guard let segmentIndex = Self.parseSegmentIndex(from: travelId),
               segmentIndex < trip.stops.count - 1 else {
             return nil
         }
@@ -960,6 +966,15 @@ struct TripDetailView: View {
         return minDay...maxDay
     }
 
+    /// Parse the segment index from a travel anchor ID.
+    /// Format: "travel:INDEX:from->to" → INDEX
+    private static func parseSegmentIndex(from travelId: String) -> Int? {
+        let stripped = travelId.replacingOccurrences(of: "travel:", with: "")
+        let parts = stripped.components(separatedBy: ":")
+        guard parts.count >= 2, let index = Int(parts[0]) else { return nil }
+        return index
+    }
+
     // MARK: - Map Helpers
 
     private func fetchDrivingRoutes() async {
@@ -1231,8 +1246,8 @@ struct TripDetailView: View {
         }
 
         // 2. Add travel items (from trip segments + overrides)
-        for segment in trip.travelSegments {
+        for (segmentIndex, segment) in trip.travelSegments.enumerated() {
-            let travelId = "travel:\(segment.fromLocation.name.lowercased())->\(segment.toLocation.name.lowercased())"
+            let travelId = stableTravelAnchorId(segment, at: segmentIndex)
 
             // Use override if available, otherwise default to day 1
             let override = travelOverrides[travelId]
@@ -1246,6 +1261,7 @@ struct TripDetailView: View {
                 kind: .travel(TravelInfo(
                     fromCity: segment.fromLocation.name,
                     toCity: segment.toLocation.name,
+                    segmentIndex: segmentIndex,
                     distanceMeters: segment.distanceMeters,
                     durationSeconds: segment.durationSeconds
                 ))
@@ -1371,9 +1387,22 @@ struct TripDetailView: View {
 
             for item in items where item.isTravel {
                 guard let travelInfo = item.travelInfo else { continue }
-                let travelId = "travel:\(travelInfo.fromCity.lowercased())->\(travelInfo.toCity.lowercased())"
+                let from = travelInfo.fromCity.lowercased()
+                let to = travelInfo.toCity.lowercased()
 
-                overrides[travelId] = TravelOverride(day: item.day, sortOrder: item.sortOrder)
+                if let segIdx = travelInfo.segmentIndex {
+                    // New format with segment index
+                    let travelId = "travel:\(segIdx):\(from)->\(to)"
+                    overrides[travelId] = TravelOverride(day: item.day, sortOrder: item.sortOrder)
+                } else {
+                    // Legacy record without segment index — derive index from trip segments
+                    if let segIdx = trip.travelSegments.firstIndex(where: {
+                        $0.fromLocation.name.lowercased() == from && $0.toLocation.name.lowercased() == to
+                    }) {
+                        let travelId = "travel:\(segIdx):\(from)->\(to)"
+                        overrides[travelId] = TravelOverride(day: item.day, sortOrder: item.sortOrder)
+                    }
+                }
             }
 
             travelOverrides = overrides
@@ -1502,20 +1531,30 @@ struct TripDetailView: View {
     private func saveTravelDayOverride(travelAnchorId: String, displayDay: Int, sortOrder: Double) async {
         print("💾 [TravelOverrides] Saving override: \(travelAnchorId) -> day \(displayDay), sortOrder \(sortOrder)")
 
-        // Parse travel ID to extract cities (format: "travel:city1->city2")
+        // Parse travel ID (format: "travel:INDEX:from->to")
+        let segmentIndex = Self.parseSegmentIndex(from: travelAnchorId)
         let stripped = travelAnchorId.replacingOccurrences(of: "travel:", with: "")
-        let parts = stripped.components(separatedBy: "->")
+        let colonParts = stripped.components(separatedBy: ":")
-        guard parts.count == 2 else {
+        // After removing "travel:", format is "INDEX:from->to"
+        let cityPart = colonParts.count >= 2 ? colonParts.dropFirst().joined(separator: ":") : stripped
+        let cityParts = cityPart.components(separatedBy: "->")
+        guard cityParts.count == 2 else {
             print("❌ [TravelOverrides] Invalid travel ID format: \(travelAnchorId)")
             return
         }
 
-        let fromCity = parts[0]
+        let fromCity = cityParts[0]
-        let toCity = parts[1]
+        let toCity = cityParts[1]
 
-        // Find existing travel item or create new one
+        // Find existing travel item matching by segment index (preferred) or city pair (legacy)
         if let existingIndex = itineraryItems.firstIndex(where: {
-            $0.isTravel && $0.travelInfo?.fromCity.lowercased() == fromCity && $0.travelInfo?.toCity.lowercased() == toCity
+            guard $0.isTravel, let info = $0.travelInfo else { return false }
+            // Match by segment index if available
+            if let idx = segmentIndex, let itemIdx = info.segmentIndex {
+                return idx == itemIdx
+            }
+            // Legacy fallback: match by city pair
+            return info.fromCity.lowercased() == fromCity && info.toCity.lowercased() == toCity
         }) {
             // Update existing
             var updated = itineraryItems[existingIndex]
@@ -1526,7 +1565,7 @@ struct TripDetailView: View {
             await ItineraryItemService.shared.updateItem(updated)
         } else {
             // Create new travel item
-            let travelInfo = TravelInfo(fromCity: fromCity, toCity: toCity)
+            let travelInfo = TravelInfo(fromCity: fromCity, toCity: toCity, segmentIndex: segmentIndex)
             let item = ItineraryItem(
                 tripId: trip.id,
                 day: displayDay,
@@ -1549,7 +1588,7 @@ struct TripDetailView: View {
 
 enum ItinerarySection {
     case day(dayNumber: Int, date: Date, games: [RichGame])
-    case travel(TravelSegment)
+    case travel(TravelSegment, segmentIndex: Int)
     case customItem(ItineraryItem)
     case addButton(day: Int)
 

SportsTimeTests/Features/Trip/ItineraryReorderingLogicTests.swift

@@ -833,7 +833,7 @@ final class ItineraryReorderingLogicTests: XCTestCase {
         ])
 
         let segment = H.makeTravelSegment(from: "CityA", to: "CityB")
-        let travelValidRanges = ["travel:citya->cityb": 1...3]
+        let travelValidRanges = ["travel:0:citya->cityb": 1...3]
 
         let zones = Logic.calculateTravelDragZones(
             segment: segment,

SportsTimeTests/Features/Trip/ItineraryRowFlatteningTests.swift

@@ -170,10 +170,11 @@ final class ItineraryRowFlatteningTests: XCTestCase {
         XCTAssertEqual(item.id, "games:2")
     }
 
-    func test_itineraryRowItem_travel_hasLowercaseId() {
+    func test_itineraryRowItem_travel_hasStableId() {
         let segment = H.makeTravelSegment(from: "Chicago", to: "Detroit")
         let item = ItineraryRowItem.travel(segment, dayNumber: 1)
-        XCTAssertEqual(item.id, "travel:chicago->detroit", "Travel ID should be lowercase")
+        XCTAssertTrue(item.id.hasPrefix("travel:"), "Travel ID should start with 'travel:'")
+        XCTAssertTrue(item.id.contains(segment.id.uuidString), "Travel ID should contain segment UUID")
     }
 
     func test_itineraryRowItem_customItem_hasUuidId() {

SportsTimeTests/Features/Trip/ItinerarySemanticTravelTests.swift

@@ -273,7 +273,7 @@ final class ItinerarySemanticTravelTests: XCTestCase {
 
         let constraints = ItineraryConstraints(tripDayCount: 4, items: [gameItemA, gameItemB])
 
-        let travelValidRanges = ["travel:citya->cityb": 1...4]
+        let travelValidRanges = ["travel:0:citya->cityb": 1...4]
 
         let validRows = Logic.computeValidDestinationRowsProposed(
             flatItems: items,

SportsTimeTests/Features/Trip/ItineraryTravelConstraintTests.swift

@@ -182,7 +182,7 @@ final class ItineraryTravelConstraintTests: XCTestCase {
         }
         controller.reloadData(
             days: [dayData],
-            travelValidRanges: ["travel:chicago->detroit": 1...1],
+            travelValidRanges: ["travel:0:chicago->detroit": 1...1],
             itineraryItems: [chicagoGame, travel]
         )
 
@@ -214,7 +214,7 @@ final class ItineraryTravelConstraintTests: XCTestCase {
         }
         controller.reloadData(
             days: [day1, day2, day3],
-            travelValidRanges: ["travel:chicago->detroit": 2...3],
+            travelValidRanges: ["travel:0:chicago->detroit": 2...3],
             itineraryItems: [travelModelItem]
         )
 
@@ -222,7 +222,7 @@ final class ItineraryTravelConstraintTests: XCTestCase {
         // Move travel (row 2) to row 3 (after Day3 header = Day 3)
         controller.tableView(controller.tableView, moveRowAt: IndexPath(row: 2, section: 0), to: IndexPath(row: 3, section: 0))
 
-        XCTAssertEqual(capturedTravelId, "travel:chicago->detroit")
+        XCTAssertEqual(capturedTravelId, "travel:0:chicago->detroit")
         XCTAssertEqual(capturedDay, 3, "Travel should now be on Day 3")
     }
 
@@ -231,7 +231,7 @@ final class ItineraryTravelConstraintTests: XCTestCase {
     func test_moveValidation_travel_snapsToValidDayRange() {
         // Given: Travel with valid range Days 2-3
         let travel = H.makeTravelSegment(from: "Chicago", to: "Detroit")
-        let travelId = "travel:chicago->detroit"
+        let travelId = "travel:0:chicago->detroit"
         let travelItem = ItineraryRowItem.travel(travel, dayNumber: 2)
         let travelModelItem = H.makeTravelItem(from: "Chicago", to: "Detroit", day: 2, sortOrder: 1.0)
 

SportsTimeTests/Features/Trip/TravelPlacementTests.swift

@@ -358,4 +358,121 @@ final class TravelPlacementTests: XCTestCase {
             XCTAssertLessThanOrEqual(day, 6, "B→C travel should be on or before Day 6")
         }
     }
+
+    // MARK: - Same-Day Collision (dictionary overwrite bug)
+
+    func test_twoSegmentsSameDay_neitherLost() {
+        // 3 back-to-back single-game stops with next-morning departures:
+        // Stop A: arrival May 1, departure May 2
+        // Stop B: arrival May 2, departure May 3
+        // Stop C: arrival May 3, departure May 4
+        //
+        // Segment 0 (A→B): fromDayNum=2, toDayNum=2 → defaultDay=2, clampedDefault=2
+        // Segment 1 (B→C): fromDayNum=3, toDayNum=3 → defaultDay=3, clampedDefault=3
+        //
+        // These don't collide, but a tighter scenario does:
+        // If A departs May 2 and B arrives May 2 AND departs May 2, C arrives May 2:
+        // Both segments resolve to Day 2 → collision.
+        //
+        // Realistic tight scenario:
+        // Stop A: May 1-1 (same-day), Stop B: May 2-2, Stop C: May 2-3
+        // Segment 0 (A→B): fromDayNum=1, toDayNum=2 → defaultDay=2
+        // Segment 1 (B→C): fromDayNum=2, toDayNum=2 → defaultDay=2
+        // Both = Day 2 → COLLISION: segment 0 overwritten.
+        let stops = [
+            makeStop(city: "CityA", arrival: may(1), departure: may(1)),
+            makeStop(city: "CityB", arrival: may(2), departure: may(2)),
+            makeStop(city: "CityC", arrival: may(2), departure: may(3))
+        ]
+        let segments = [
+            makeSegment(from: "CityA", to: "CityB"),
+            makeSegment(from: "CityB", to: "CityC")
+        ]
+
+        let trip = Trip(
+            name: "Tight Trip",
+            preferences: TripPreferences(),
+            stops: stops,
+            travelSegments: segments,
+            totalGames: 0,
+            totalDistanceMeters: 0,
+            totalDrivingSeconds: 0
+        )
+
+        let days = tripDays(from: may(1), to: may(3))
+        let result = TravelPlacement.computeTravelByDay(trip: trip, tripDays: days)
+
+        // Both segments must be present — neither should be silently dropped
+        let allSegments = result.values.flatMap { $0 }
+        XCTAssertEqual(allSegments.count, 2, "Both travel segments must be preserved (no collision)")
+
+        // Day 2 should have both segments
+        let day2Segments = result[2] ?? []
+        XCTAssertEqual(day2Segments.count, 2, "Day 2 should have 2 travel segments")
+    }
+
+    // MARK: - Repeat City Pair ID Collision
+
+    func test_repeatCityPair_overridesDoNotCollide() {
+        // Follow Team pattern: Houston→Cincinnati→Houston→Cincinnati
+        // Two segments share the same city pair (Houston→Cincinnati)
+        // Each must get a unique travel anchor ID so overrides don't collide.
+        let stops = [
+            makeStop(city: "Houston", arrival: may(1), departure: may(2)),      // Stop 0
+            makeStop(city: "Cincinnati", arrival: may(4), departure: may(5)),   // Stop 1
+            makeStop(city: "Houston", arrival: may(7), departure: may(8)),      // Stop 2
+            makeStop(city: "Cincinnati", arrival: may(10), departure: may(11))  // Stop 3
+        ]
+
+        let segments = [
+            makeSegment(from: "Houston", to: "Cincinnati"),   // Seg 0: stops[0] → stops[1]
+            makeSegment(from: "Cincinnati", to: "Houston"),   // Seg 1: stops[1] → stops[2]
+            makeSegment(from: "Houston", to: "Cincinnati")    // Seg 2: stops[2] → stops[3]
+        ]
+
+        // Simulate what stableTravelAnchorId should produce WITH segment index
+        let id0 = "travel:0:houston->cincinnati"
+        let id1 = "travel:1:cincinnati->houston"
+        let id2 = "travel:2:houston->cincinnati"
+
+        // All IDs must be unique
+        XCTAssertNotEqual(id0, id2, "Repeat city pair segments must have unique IDs")
+        XCTAssertEqual(Set([id0, id1, id2]).count, 3, "All 3 travel IDs must be unique")
+
+        // Simulate overrides dictionary — each segment gets its own entry
+        var overrides: [String: Int] = [:]  // travel ID → day override
+        overrides[id0] = 3   // Seg 0 overridden to day 3
+        overrides[id2] = 9   // Seg 2 overridden to day 9
+
+        // Verify no collision — seg 0 override is NOT overwritten by seg 2
+        XCTAssertEqual(overrides[id0], 3, "Segment 0 override should be day 3")
+        XCTAssertEqual(overrides[id2], 9, "Segment 2 override should be day 9")
+        XCTAssertNil(overrides[id1], "Segment 1 has no override")
+    }
+
+    func test_singleSegmentPerDay_returnsArrayOfOne() {
+        // Ensure the new array return type still works for the simple case
+        let stops = [
+            makeStop(city: "Houston", arrival: may(1), departure: may(3)),
+            makeStop(city: "Chicago", arrival: may(5), departure: may(6))
+        ]
+        let segments = [makeSegment(from: "Houston", to: "Chicago")]
+
+        let trip = Trip(
+            name: "Simple",
+            preferences: TripPreferences(),
+            stops: stops,
+            travelSegments: segments,
+            totalGames: 0,
+            totalDistanceMeters: 0,
+            totalDrivingSeconds: 0
+        )
+
+        let days = tripDays(from: may(1), to: may(6))
+        let result = TravelPlacement.computeTravelByDay(trip: trip, tripDays: days)
+
+        XCTAssertEqual(result.count, 1, "Should have 1 day with travel")
+        let day4Segments = result[4] ?? []
+        XCTAssertEqual(day4Segments.count, 1, "Day 4 should have exactly 1 travel segment")
+    }
 }