Tab Bar Load Animation

Nucleic-Session: EEC60FAE-8368-49CA-9202-7026C12E7F8C
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Views/AdaptiveRootView.swift

@@ -38,31 +38,51 @@ struct CompactRootView: View {
     @Environment(\.accessibilityReduceMotion) private var reduceMotion
     // Initial tab; overridable via NUCLEIC_TAB for offline UI previews.
     @State private var tab = Int(ProcessInfo.processInfo.environment["NUCLEIC_TAB"] ?? "") ?? 0
+    /// The shared "+" beside the tab bar opens the project-picker composer (the per-page discs are
+    /// gone on compact — this one bar owns "new chat").
+    @State private var showNewChat = false
+    /// Measured height of the floating bar, fed back into the bottom inset so tab content lays out
+    /// exactly above it (no guessing, no overlap).
+    @State private var barHeight: CGFloat = 72
 
     /// The bar owns the bottom edge on the top-level tabs, but yields it to a pushed session's
     /// floating glass chat bar — so it's hidden exactly while a session detail is on screen
     /// (`openSessionID` is set by `SessionDetailView`'s appear/disappear, our animation trigger).
     private var showsTabBar: Bool { store.openSessionID == nil }
 
+    /// The "+" is inert without control scope or a project to start in, so it's shown only when a
+    /// chat could actually be kicked off (mirrors `NewChatAffordance.canStart`).
+    private var canStartChat: Bool { store.canControl && !store.dashboard.projects.isEmpty }
+
     var body: some View {
         TabView(selection: $tab) {
             HomeView().tag(0).toolbar(.hidden, for: .tabBar)
             SessionsView().tag(1).toolbar(.hidden, for: .tabBar)
             ProjectsView().tag(2).toolbar(.hidden, for: .tabBar)
-            TodosView().tag(3).toolbar(.hidden, for: .tabBar)
-            SettingsView().tag(4).toolbar(.hidden, for: .tabBar)
+            SettingsView().tag(3).toolbar(.hidden, for: .tabBar)
         }
-        // Our bar sits in a bottom inset so top-level content (and each tab's floating "+") lays
-        // out above it; a pushed session sees the inset collapse and runs its transcript full-bleed
-        // to the bottom. Both the slide and that reflow ride the one spring below.
+        // Reserve exactly the bar's height so top-level content (and each tab's own bottom chrome)
+        // lays out above the floating bar rather than under it; collapses to nothing when a session
+        // hides the bar so the transcript runs full-bleed.
         .safeAreaInset(edge: .bottom, spacing: 0) {
-            if showsTabBar {
-                NucleicTabBar(selection: $tab, needsYou: store.needsYouCount)
-                    .transition(.move(edge: .bottom))
+            Color.clear.frame(height: showsTabBar ? barHeight : 0)
         }
+        // The bar itself lives in an always-mounted overlay and slides on `offset`, so it travels
+        // continuously off the bottom of the screen (a fixed distance past the home-indicator curve)
+        // instead of a transition that removes it mid-descent and makes it pop.
+        .overlay(alignment: .bottom) {
+            bottomBar
+                .background(
+                    GeometryReader { geo in
+                        Color.clear.preference(key: BarHeightKey.self, value: geo.size.height)
+                    })
+                .onPreferenceChange(BarHeightKey.self) { barHeight = $0 }
+                .offset(y: showsTabBar ? 0 : barHeight + 120)
         }
-        .animation(reduceMotion ? nil : .spring(response: 0.34, dampingFraction: 0.92),
+        .animation(reduceMotion ? nil : .spring(response: 0.38, dampingFraction: 0.9),
                    value: showsTabBar)
+        // The project-picker composer, presented for the shared "+" (no per-page disc on compact).
+        .newChatAffordance(isPresented: $showNewChat, showsButton: false)
         // A notification tap routes to its session by jumping to the Sessions tab.
         .onChange(of: store.pendingRoute) { _, route in
             if route != nil { tab = 1 }
@@ -72,15 +92,43 @@ struct CompactRootView: View {
             if show { tab = 1; store.pendingSessionsList = false }
         }
     }
+
+    /// The floating bottom bar: the tab capsule, with the "+" disc riding to its right in the width
+    /// freed by dropping the To-dos tab (the iOS 26 tab-bar-plus-accessory shape).
+    private var bottomBar: some View {
+        HStack(spacing: 10) {
+            NucleicTabBar(selection: $tab, needsYou: store.needsYouCount)
+            if canStartChat {
+                Button { showNewChat = true } label: {
+                    Image(systemName: "plus")
+                        .font(.system(size: 22, weight: .semibold))
+                        .foregroundStyle(Palette.accent)
+                        .frame(width: 56, height: 56)
+                        .contentShape(Circle())
+                        .glassCircle()
+                }
+                .buttonStyle(.plain)
+                .accessibilityLabel("New chat")
+            }
+        }
+        .padding(.horizontal, 16)
+        .padding(.bottom, 4)
+    }
 }
 
-/// Our own bottom tab bar for the compact shell — a floating Liquid Glass capsule of five items,
-/// standing in for the system tab bar so `CompactRootView` can animate its visibility itself (see
-/// that view for why) while keeping the iOS 26 floating-glass look. Real `glassEffect` on iOS 26;
-/// an ultra-thin material capsule with a hairline edge + soft shadow on earlier systems, matching
-/// the app's `glassSurface`/`glassCircle`. It floats inset from the edges, above the home
-/// indicator — it does not bleed to the screen edge. The Sessions item carries the "needs you"
-/// badge the system tab item used to.
+/// A preference carrying the floating bar's measured height up to `CompactRootView`, which feeds it
+/// back into the bottom safe-area inset so content sits exactly above the bar.
+private struct BarHeightKey: PreferenceKey {
+    static var defaultValue: CGFloat = 72
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) { value = nextValue() }
+}
+
+/// Our own bottom tab bar for the compact shell — a floating Liquid Glass capsule of four items
+/// (Home, Sessions, Projects, Settings), standing in for the system tab bar so `CompactRootView`
+/// can animate its visibility itself (see that view for why) while keeping the iOS 26 floating-glass
+/// look. Real `glassEffect` on iOS 26; an ultra-thin material capsule with a hairline edge + soft
+/// shadow on earlier systems, matching the app's `glassSurface`/`glassCircle`. The Sessions item
+/// carries the "needs you" badge the system tab item used to.
 struct NucleicTabBar: View {
     @Binding var selection: Int
     /// Sessions blocking on a human — the red badge on the Sessions item (was the tab item badge).
@@ -91,8 +139,7 @@ struct NucleicTabBar: View {
         Item(index: 0, title: "Home", icon: "house"),
         Item(index: 1, title: "Sessions", icon: "square.stack.3d.up"),
         Item(index: 2, title: "Projects", icon: "folder"),
-        Item(index: 3, title: "To-dos", icon: "checklist"),
-        Item(index: 4, title: "Settings", icon: "gearshape"),
+        Item(index: 3, title: "Settings", icon: "gearshape"),
     ]
 
     var body: some View {
@@ -104,10 +151,6 @@ struct NucleicTabBar: View {
         .padding(.horizontal, 6)
         .padding(.vertical, 8)
         .glassBar()
-        // Float the capsule inset from the edges and just above the home indicator, rather than
-        // filling the bottom edge like the old opaque bar.
-        .padding(.horizontal, 16)
-        .padding(.bottom, 4)
     }
 
     private func itemButton(_ item: Item) -> some View {