fix(ui): drop toasts under sheets and swap the countdown in place

.claude/docs/architecture.md

@@ -60,7 +60,7 @@ Every router mutation logs one INFO entry under `flipcash.router` — filter by
 
 ## Toasts: ToastController
 
-Floating toasts go through `ToastController` (FlipcashUI), held on `Container` and injected via `@Environment(ToastController.self)`. Call `toasts.show(.init(...))`; **don't add a screen-level toast overlay or `@State` timer.** `HomeTabView` hosts the one toast with `.toastHost(_:)`, which sits it above the floating tab bar (native bar on iOS 26+, legacy pill below) or at the screen's bottom edge when the bar is hidden. A new toast replaces the one showing. A toast with an action takes touches and swipes down to dismiss; one without lets touches through. Sheets cover the host, so a toast dispatched while a sheet is up runs out its time hidden behind it. The bill screen's balance toast (`Session.toast`) is a separate system.
+Floating toasts go through `ToastController` (FlipcashUI), held on `Container` and injected via `@Environment(ToastController.self)`. Call `toasts.show(.init(...))`; **don't add a screen-level toast overlay or `@State` timer.** `HomeTabView` hosts the one toast with `.toastHost(_:)`, which sits it above the floating tab bar (native bar on iOS 26+, legacy pill below) or at the screen's bottom edge when the bar is hidden. A new toast replaces the one showing. A toast with an action takes touches and swipes down to dismiss; one without lets touches through. A sheet, dialog or the bill covers the host: `HomeTabView` sets `isCovered` from router sheets and the bill, which dismisses the toast showing, and `show` drops any toast dispatched while something is presented. For a message that updates as the user acts (a countdown), pass `inPlace: true` so it swaps text without replaying the entrance. The bill screen's balance toast (`Session.toast`) is a separate system.
 
 ## Key Architectural Concepts
 

Flipcash/Core/Screens/Main/Home/HomeTabView.swift

@@ -106,6 +106,9 @@ struct HomeTabView: View {
                 tipCardPresentation.collapse()
             }
             .onDisappear { router.activeTabStack = nil }
+            .onChange(of: router.presentedSheet != nil || sessionContainer.session.isShowingBill, initial: true) { _, covered in
+                container.toasts.isCovered = covered
+            }
             .onChange(of: sessionContainer.session.profile?.username, initial: true) { _, username in
                 sessionContainer.chatArchive.setViewerUsername(username)
             }

Flipcash/Core/Screens/Main/You/YouScreen.swift

@@ -462,9 +462,12 @@ struct YouScreen: View {
                 betaFlags.setAccessGranted(!betaFlags.accessGranted)
             }
             if let message {
-                // Two seconds, so consecutive taps read as one countdown. Without an action the toast
+                // Two seconds and swapped in place, so consecutive taps read as one countdown. Without an action the toast
                 // lets taps through, so it never blocks the version string at the bottom of the list.
-                toasts.show(.init(message, messageIdentifier: "you-version-toast", width: .fit, duration: .seconds(2)))
+                toasts.show(
+                    .init(message, messageIdentifier: "you-version-toast", width: .fit, duration: .seconds(2)),
+                    inPlace: true
+                )
             }
         } label: {
             Text("Version \(AppMeta.version) • Build \(AppMeta.build)")

FlipcashTests/ToastControllerTests.swift

@@ -0,0 +1,81 @@
+//
+//  ToastControllerTests.swift
+//  FlipcashTests
+//
+
+import Foundation
+import Testing
+@testable import FlipcashUI
+
+@MainActor
+@Suite("Toast controller")
+struct ToastControllerTests {
+
+    @Test("A new toast replaces the one showing")
+    func replaces() {
+        let toasts = ToastController()
+        toasts.show(.init("First"))
+        toasts.show(.init("Second"))
+
+        #expect(toasts.current?.message == "Second")
+    }
+
+    @Test("Covering the host dismisses the toast showing")
+    func coverDismisses() {
+        let toasts = ToastController()
+        toasts.show(.init("Chat archived"))
+
+        toasts.isCovered = true
+
+        #expect(toasts.current == nil)
+    }
+
+    @Test("A toast shown while covered is dropped, and uncovering does not bring it back")
+    func coveredDrops() {
+        let toasts = ToastController()
+        toasts.isCovered = true
+        toasts.show(.init("Chat archived"))
+        #expect(toasts.current == nil)
+
+        toasts.isCovered = false
+
+        #expect(toasts.current == nil)
+    }
+
+    @Test("An in-place toast keeps the slot of the one showing, so the entrance does not replay")
+    func inPlaceKeepsSlot() throws {
+        let toasts = ToastController()
+        toasts.show(.init("3 steps"), inPlace: true)
+        let first = try #require(toasts.current)
+
+        toasts.show(.init("2 steps"), inPlace: true)
+        let second = try #require(toasts.current)
+
+        #expect(second.message == "2 steps")
+        #expect(second.slot == first.slot)
+        #expect(second.id != first.id)
+    }
+
+    @Test("A toast not shown in place takes a new slot")
+    func replacementTakesNewSlot() throws {
+        let toasts = ToastController()
+        toasts.show(.init("First"))
+        let first = try #require(toasts.current)
+
+        toasts.show(.init("Second"))
+
+        #expect(toasts.current?.slot != first.slot)
+    }
+
+    @Test("Dismissing a replaced toast leaves the current one up")
+    func staleDismissIgnored() throws {
+        let toasts = ToastController()
+        toasts.show(.init("First"))
+        let first = try #require(toasts.current)
+        toasts.show(.init("Second"))
+
+        toasts.dismiss(first.id)
+
+        #expect(toasts.current?.message == "Second")
+    }
+}

FlipcashUI/Sources/FlipcashUI/Views/Containers/ToastController.swift

@@ -4,6 +4,7 @@
 //
 
 import SwiftUI
+import UIKit
 import Observation
 
 /// The app-wide toast: any screen dispatches one, and a single host draws it above the floating tab bar,
@@ -16,6 +17,8 @@ public final class ToastController {
     /// lets touches through to the screen beneath it.
     public struct Toast: Identifiable {
         public let id = UUID()
+        // Shared by toasts swapped in place, so the host keeps the view rather than replaying the entrance.
+        fileprivate(set) var slot = UUID()
         let message: String
         let systemImage: String?
         let messageIdentifier: String?
@@ -46,11 +49,25 @@ public final class ToastController {
     /// The toast on screen, or `nil` when none is.
     public private(set) var current: Toast?
 
+    /// Whether a sheet or other modal layer is drawn over the host. Covering dismisses the toast on screen,
+    /// and a toast shown while covered is dropped: hidden beneath the layer it would time out unseen, with
+    /// its action out of reach.
+    public var isCovered = false {
+        didSet { if isCovered { current = nil } }
+    }
+
     /// A controller with no toast showing.
     public init() {}
 
-    /// Shows `toast` in place of any toast already up, and announces it to VoiceOver.
-    public func show(_ toast: Toast) {
+    /// Shows `toast` in place of any toast already up, and announces it to VoiceOver. Drops it while the
+    /// host is covered.
+    ///
+    /// With `inPlace`, a toast already up swaps its content without replaying the entrance, for a message
+    /// that updates as the user acts (a countdown). Its timer still restarts.
+    public func show(_ toast: Toast, inPlace: Bool = false) {
+        guard !isCovered, !Self.isPresentingOverApp else { return }
+        var toast = toast
+        if inPlace, let current { toast.slot = current.slot }
         current = toast
         AccessibilityNotification.Announcement(toast.message).post()
     }
@@ -60,6 +77,16 @@ public final class ToastController {
         guard current?.id == id else { return }
         current = nil
     }
+
+    // Catches sheets and dialogs presented outside the router, which never set `isCovered`.
+    private static var isPresentingOverApp: Bool {
+        UIApplication.shared.connectedScenes
+            .compactMap { $0 as? UIWindowScene }
+            .flatMap(\.windows)
+            .first(where: \.isKeyWindow)?
+            .rootViewController?
+            .presentedViewController != nil
+    }
 }
 
 extension View {
@@ -104,13 +131,13 @@ private struct ToastHost: View {
                 .allowsHitTesting(toast.action != nil)
                 .padding(.bottom, bottomPadding)
                 .floatingToastTransition()
-                .id(toast.id)
+                .id(toast.slot)
                 .task(id: toast.id) {
                     try? await Task.sleep(for: toast.duration)
                     if !Task.isCancelled { controller.dismiss(toast.id) }
                 }
             }
         }
-        .animation(.spring(duration: 0.4, bounce: 0.2), value: controller.current?.id)
+        .animation(.spring(duration: 0.4, bounce: 0.2), value: controller.current?.slot)
     }
 }