fix(WhereUI): guard Settings navigation footprints

.agents/skills/building-ui/SKILL.md

@@ -113,6 +113,13 @@ module-owned stylesheets.
   than remain at zero opacity.
 - Keep the visual structure consistent across states and variants unless the
   difference is intentional and modeled by the component style.
+- Put a large declarative subtree behind a nominal child `View` before passing
+  it through a custom generic container that stores or repeatedly transforms
+  its `Content`. In particular, do not pass a multi-section `Form` or `List`
+  directly into such a wrapper: SwiftUI may copy the full concrete value on the
+  stack while applying environment or navigation updates. Treat a DEBUG-only
+  content-footprint guard as a heuristic tripwire for extraction, not a
+  shipping layout contract or a threshold to retune around.
 
 ## Build for accessibility and localization
 

Where/WhereUI/AGENTS.md

@@ -83,6 +83,15 @@ Layering, localization, preview, and testing conventions live in the feature
   ([`Sources/Shared/MotionIsStatic.swift`](Sources/Shared/MotionIsStatic.swift))
   for its static end-state — never hand-roll the
   `\.accessibilityReduceMotion` + `\.isCapturingSnapshot` pair.
+- Pass large `Form`/`List` subtrees through a nominal child before
+  `SettingsFocusScope`; `SettingsRouteViewTests` exercises every push
+  destination and its nested heterogeneous routes against the DEBUG-only
+  value-size tripwire.
+- Keep the Settings content-footprint tripwire DEBUG-only; Release has no
+  footprint precondition.
+- Diagnostic: `EXC_BAD_ACCESS` / `___chkstk_darwin` followed by
+  `View.environment<T>` during a navigation push means inspect concrete content
+  stored by generic wrappers.
 - A step joins `WhereLaunch`'s plan through `.measured()` and so must declare a
   `budget` (`BudgetedLaunchStep`) — see [Spans](../AGENTS.md#spans). WhereUI also
   owns log retention: `LogHistoryPruner` bounds the store by age *and* event

Where/WhereUI/Sources/Settings/FeaturePreviews/Evidence/ShareEvidenceFeaturesView.swift

@@ -116,7 +116,7 @@ struct ShareEvidenceFeaturesView: View {
         }
     }
 
-    private enum Route: Hashable {
+    enum Route: Hashable {
         case archive
     }
 }

Where/WhereUI/Sources/Settings/SettingsRouteView.swift

@@ -0,0 +1,72 @@
+import SwiftUI
+
+/// Builds one pushed Settings destination from the root's typed route and
+/// view-scoped collaborators. Keeping route rendering in a nominal child lets
+/// tests exercise the same destination tree without a test-only Settings API.
+struct SettingsRouteView: View {
+    let route: SettingsRoute
+    let report: YearReportModel
+    let backup: BackupModel
+    let reminders: RemindersSettingsModel
+
+    @Environment(WhereSession.self) private var session
+
+    var body: some View {
+        switch route.destination {
+            case .attachments:
+                EvidenceListView(report: report)
+            case .loggedDays:
+                LoggedDaysView(report: report)
+            case .devices:
+                DevicesSettingsView(session: session, focus: route.focus)
+            case .regions:
+                // Regions is presented as a sheet (`isSheet`), so it's never
+                // routed here; this arm only keeps the switch exhaustive.
+                EmptyView()
+            case .alerts:
+                AlertsSettingsView(report: report, reminders: reminders, focus: route.focus)
+            case .appearance:
+                AppearanceSettingsView(report: report, focus: route.focus)
+            case .year:
+                VisibleYearSettingsView(report: report, focus: route.focus)
+            case .siri:
+                SiriFeaturesView(
+                    focus: route.focus,
+                    presentation: featureDiscoveryPresentation,
+                )
+            case .widgets:
+                WidgetFeaturesView(
+                    focus: route.focus,
+                    presentation: featureDiscoveryPresentation,
+                )
+            case .shareEvidence:
+                ShareEvidenceFeaturesView(
+                    report: report,
+                    focus: route.focus,
+                    presentation: featureDiscoveryPresentation,
+                )
+            case .estimatedTime:
+                EstimatedTimeFeaturesView(report: report, focus: route.focus)
+            case .insightsAccuracy:
+                InsightsAccuracyFeaturesView(
+                    report: report,
+                    focus: route.focus,
+                )
+            case .personalization:
+                PersonalizationFeaturesView(report: report, focus: route.focus)
+            case .data:
+                DataSettingsView(report: report, backup: backup, focus: route.focus)
+            case .about:
+                AboutSettingsView(focus: route.focus)
+        }
+    }
+
+    private var featureDiscoveryPresentation: FeatureDiscoveryPresentation {
+        FeatureDiscoveryPresentation(
+            report: report.report,
+            selectedYear: report.selectedYear,
+            referenceDate: report.referenceDate,
+            calendar: report.calendar,
+        )
+    }
+}

Where/WhereUI/Sources/Settings/SettingsRow.swift

@@ -97,6 +97,16 @@ struct SettingsRowModifier: ViewModifier {
 /// (no fade — still scrolls and shows a brief static highlight). Flashes once per
 /// appearance so returning to the screen doesn't re-flash.
 struct SettingsFocusScope<Content: View>: View {
+    #if DEBUG
+        /// A DEBUG-only heuristic separating the largest known-safe Settings form
+        /// (46,912 bytes) from the 62,680-byte concrete value that overflowed a
+        /// device stack while SwiftUI applied this scope's environment during a
+        /// navigation push. Large trees belong behind a small nominal child view.
+        static var maximumContentFootprint: Int {
+            56 * 1024
+        }
+    #endif
+
     let focus: SettingsFocus?
     let isReady: Bool
     let content: Content
@@ -113,6 +123,14 @@ struct SettingsFocusScope<Content: View>: View {
     ) {
         self.focus = focus
         self.isReady = isReady
+        #if DEBUG
+            let contentFootprint = MemoryLayout<Content>.size
+            precondition(
+                contentFootprint <= Self.maximumContentFootprint,
+                "SettingsFocusScope Content is \(contentFootprint) bytes; extract its large "
+                    + "Form/List subtree behind a nominal child View.",
+            )
+        #endif
         self.content = content()
     }
 

Where/WhereUI/Sources/Settings/SettingsSearch.swift

@@ -3,8 +3,8 @@ import SwiftUI
 
 /// The top-level Settings groups. Each drills into its own sub-screen; the
 /// top-level list and `SettingsRoute` route on these, and the
-/// `navigationDestination` switch (in `SettingsView`) builds a screen for every
-/// case with no `default:`, so adding a case is a compile error until wired.
+/// `SettingsRouteView` switch builds a screen for every case with no `default:`,
+/// so adding a case is a compile error until wired.
 enum SettingsDestination: Hashable, CaseIterable {
     case attachments
     case loggedDays

Where/WhereUI/Sources/Settings/SettingsView.swift

@@ -104,7 +104,12 @@ struct SettingsView: View {
                 }
             }
             .navigationDestination(for: SettingsRoute.self) { route in
-                destination(for: route)
+                SettingsRouteView(
+                    route: route,
+                    report: report,
+                    backup: backup,
+                    reminders: reminders,
+                )
             }
             .sheet(isPresented: $showRegions) {
                 RegionsSettingsView(usedThisYear: regionsUsedThisYear)
@@ -254,73 +259,13 @@ struct SettingsView: View {
         }
     }
 
-    @ViewBuilder
-    private func destination(for route: SettingsRoute) -> some View {
-        switch route.destination {
-            case .attachments:
-                EvidenceListView(report: report)
-            case .loggedDays:
-                LoggedDaysView(report: report)
-            case .devices:
-                DevicesSettingsView(session: session, focus: route.focus)
-            case .regions:
-                // Regions is presented as a sheet (`isSheet`), so it's never
-                // routed here; this arm only keeps the switch exhaustive.
-                EmptyView()
-            case .alerts:
-                AlertsSettingsView(report: report, reminders: reminders, focus: route.focus)
-            case .appearance:
-                AppearanceSettingsView(report: report, focus: route.focus)
-            case .year:
-                VisibleYearSettingsView(report: report, focus: route.focus)
-            case .siri:
-                SiriFeaturesView(
-                    focus: route.focus,
-                    presentation: featureDiscoveryPresentation,
-                )
-            case .widgets:
-                WidgetFeaturesView(
-                    focus: route.focus,
-                    presentation: featureDiscoveryPresentation,
-                )
-            case .shareEvidence:
-                ShareEvidenceFeaturesView(
-                    report: report,
-                    focus: route.focus,
-                    presentation: featureDiscoveryPresentation,
-                )
-            case .estimatedTime:
-                EstimatedTimeFeaturesView(report: report, focus: route.focus)
-            case .insightsAccuracy:
-                InsightsAccuracyFeaturesView(
-                    report: report,
-                    focus: route.focus,
-                )
-            case .personalization:
-                PersonalizationFeaturesView(report: report, focus: route.focus)
-            case .data:
-                DataSettingsView(report: report, backup: backup, focus: route.focus)
-            case .about:
-                AboutSettingsView(focus: route.focus)
-        }
-    }
-
     /// Regions with days in the selected report year, so the region editor can
     /// surface a "used this year" group (grouping order only — it doesn't affect
     /// what's saved). `.other` isn't a pickable region, so it's dropped.
     private var regionsUsedThisYear: Set<Region> {
         guard let totals = report.report?.totals else { return [] }
         return Set(totals.filter { $0.key != .other && $0.value > 0 }.map(\.key))
     }
-
-    private var featureDiscoveryPresentation: FeatureDiscoveryPresentation {
-        FeatureDiscoveryPresentation(
-            report: report.report,
-            selectedYear: report.selectedYear,
-            referenceDate: report.referenceDate,
-            calendar: report.calendar,
-        )
-    }
 }
 
 #if DEBUG