fix(chat): slash-menu filter, auto-scroll on send/complete, loading state

- Slash menu: filter at the parent and pass the pre-filtered list to
  SlashCommandMenu (pure-prefix match, no description fallback). Adds
  `.id(menuQuery)` to force a fresh view on every query so SwiftUI can't
  render stale props — this was the cause of "typing /mo still shows
  /help" (the old description fallback plus a cached child view kept
  /help pinned regardless of query).
- Auto-scroll to bottom when the user submits a message and again when
  the prompt completes. `.defaultScrollAnchor(.bottom)` handles slow
  streaming fine, but rapid slash-command responses outran the anchor
  and left the response off-screen.
- Loading state: add `ChatViewModel.isPreparingSession` (true during
  Starting / Creating / Loading / Reconnecting). While true, the message
  list swaps its placeholder for a ProgressView — non-blocking, just a
  view inside the ScrollView.
- Center the empty-state placeholder properly: replace
  `.padding(.vertical, 80)` with Spacers inside
  `.containerRelativeFrame(.vertical)` so the placeholder sits in the
  true vertical center of the chat pane at any window size.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scarf/scarf/Features/Chat/ViewModels/ChatViewModel.swift

@@ -50,6 +50,23 @@ final class ChatViewModel {
     private var isHandlingDisconnect = false
     var isACPConnected: Bool { acpClient != nil && hasActiveProcess }
     var acpStatus: String = ""
+
+    /// True while a session is being established or restored — from the user
+    /// kicking off "start chat" or "resume session" until the ACP session is
+    /// ready for messages. The chat pane uses this to show a loader in place
+    /// of the empty-state placeholder.
+    var isPreparingSession: Bool {
+        guard hasActiveProcess else { return false }
+        switch acpStatus {
+        case "Starting...",
+             "Creating session...",
+             "Creating new session...",
+             "Loading session...":
+            return true
+        default:
+            return acpStatus.hasPrefix("Reconnecting")
+        }
+    }
     var acpError: String?
     /// Human-readable hint derived from error + stderr (e.g. "set ANTHROPIC_API_KEY").
     /// Shown above the raw error in the UI when present.

scarf/scarf/Features/Chat/ViewModels/RichChatViewModel.swift

@@ -170,6 +170,11 @@ final class RichChatViewModel {
         streamingThinkingText = ""
         streamingToolCalls = []
         buildMessageGroups()
+        // User just submitted — jump to the bottom so they see their message
+        // and the incoming response. `.defaultScrollAnchor(.bottom)` handles
+        // slow streaming fine, but rapid responses (slash commands especially)
+        // arrive faster than the anchor can track.
+        requestScrollToBottom()
     }
 
     /// Process a streaming ACP event and update the message list.
@@ -337,6 +342,10 @@ final class RichChatViewModel {
         acpCachedReadTokens += response.cachedReadTokens
         isAgentWorking = false
         buildMessageGroups()
+        // Final position after the prompt settles. Catches fast responses
+        // (slash commands, short replies) where `.defaultScrollAnchor(.bottom)`
+        // didn't quite track the abrupt content growth.
+        requestScrollToBottom()
     }
 
     private func handleConnectionLost(reason: String) {

scarf/scarf/Features/Chat/Views/RichChatInputBar.swift

@@ -17,11 +17,12 @@ struct RichChatInputBar: View {
         VStack(alignment: .leading, spacing: 0) {
             if showMenu {
                 SlashCommandMenu(
-                    commands: commands,
-                    query: menuQuery,
+                    commands: filteredCommands,
+                    agentHasCommands: !commands.isEmpty,
                     selectedIndex: $selectedIndex,
                     onSelect: insertCommand
                 )
+                .id(menuQuery)
                 .background(.regularMaterial)
                 .overlay(
                     RoundedRectangle(cornerRadius: 10)

scarf/scarf/Features/Chat/Views/RichChatMessageList.swift

@@ -3,6 +3,10 @@ import SwiftUI
 struct RichChatMessageList: View {
     let groups: [MessageGroup]
     let isWorking: Bool
+    /// True while the ACP session is being established or restored — used to
+    /// swap the empty-state placeholder for a progress indicator so the user
+    /// knows something is happening while history loads.
+    var isLoadingSession: Bool = false
     /// External trigger to force a scroll-to-bottom (e.g., from "Return to Active Session").
     var scrollTrigger: UUID = UUID()
 
@@ -28,7 +32,23 @@ struct RichChatMessageList: View {
             ScrollView {
                 VStack(alignment: .leading, spacing: 16) {
                     if groups.isEmpty && !isWorking {
-                        emptyState
+                        // Fill the scroll view's visible height so Spacers
+                        // can vertically center the placeholder. Previously
+                        // `.padding(.vertical, 80)` left the placeholder
+                        // floating at whatever y-offset `.defaultScrollAnchor(.bottom)`
+                        // settled on — usually near the bottom of the pane.
+                        VStack {
+                            Spacer(minLength: 0)
+                            if isLoadingSession {
+                                loadingState
+                            } else {
+                                emptyState
+                            }
+                            Spacer(minLength: 0)
+                        }
+                        .frame(maxWidth: .infinity)
+                        .containerRelativeFrame(.vertical)
+                        .transition(.opacity)
                     }
 
                     ForEach(groups) { group in
@@ -42,6 +62,8 @@ struct RichChatMessageList: View {
                     }
                 }
                 .padding()
+                .animation(.easeInOut(duration: 0.15), value: isLoadingSession)
+                .animation(.easeInOut(duration: 0.15), value: groups.isEmpty)
             }
             .defaultScrollAnchor(.bottom)
             .onChange(of: scrollTrigger) {
@@ -75,8 +97,16 @@ struct RichChatMessageList: View {
                 .foregroundStyle(.secondary)
                 .multilineTextAlignment(.center)
         }
-        .frame(maxWidth: .infinity)
-        .padding(.vertical, 80)
+    }
+
+    private var loadingState: some View {
+        VStack(spacing: 14) {
+            ProgressView()
+                .controlSize(.large)
+            Text("Loading session…")
+                .font(.callout)
+                .foregroundStyle(.secondary)
+        }
     }
 
     private var typingIndicator: some View {

scarf/scarf/Features/Chat/Views/RichChatView.swift

@@ -28,6 +28,7 @@ struct RichChatView: View {
             RichChatMessageList(
                 groups: richChat.messageGroups,
                 isWorking: richChat.isAgentWorking,
+                isLoadingSession: chatViewModel.isPreparingSession,
                 scrollTrigger: richChat.scrollTrigger
             )
 

scarf/scarf/Features/Chat/Views/SlashCommandMenu.swift

@@ -1,29 +1,27 @@
 import SwiftUI
 
 /// Floating menu of available slash commands shown above the chat input when
-/// the user types `/` as the first character. Read-only list — the parent
-/// owns selection state and insertion.
+/// the user types `/` as the first character. Purely presentational — the
+/// parent filters the list and owns selection state.
 struct SlashCommandMenu: View {
+    /// Pre-filtered commands to display.
     let commands: [HermesSlashCommand]
-    let query: String
+    /// Whether the agent advertised any commands at all. Lets us distinguish
+    /// "agent hasn't sent commands yet" from "filter matched nothing".
+    let agentHasCommands: Bool
     @Binding var selectedIndex: Int
     var onSelect: (HermesSlashCommand) -> Void
 
-    var filtered: [HermesSlashCommand] {
-        Self.filter(commands: commands, query: query)
-    }
-
+    /// Case-insensitive prefix match on the command name. Exposed as a static
+    /// helper so the parent can share filter logic with its key handlers.
     static func filter(commands: [HermesSlashCommand], query: String) -> [HermesSlashCommand] {
         let q = query.lowercased()
         if q.isEmpty { return commands }
-        let prefix = commands.filter { $0.name.lowercased().hasPrefix(q) }
-        if !prefix.isEmpty { return prefix }
-        return commands.filter { $0.description.lowercased().contains(q) }
+        return commands.filter { $0.name.lowercased().hasPrefix(q) }
     }
 
     var body: some View {
-        let items = filtered
-        if commands.isEmpty {
+        if !agentHasCommands {
             VStack(alignment: .leading, spacing: 4) {
                 Text("No commands available")
                     .font(.callout)
@@ -34,7 +32,7 @@ struct SlashCommandMenu: View {
             }
             .padding(12)
             .frame(minWidth: 360, alignment: .leading)
-        } else if items.isEmpty {
+        } else if commands.isEmpty {
             VStack(alignment: .leading, spacing: 4) {
                 Text("No matching commands")
                     .font(.callout)
@@ -49,7 +47,7 @@ struct SlashCommandMenu: View {
             ScrollViewReader { proxy in
                 ScrollView {
                     LazyVStack(spacing: 0) {
-                        ForEach(Array(items.enumerated()), id: \.element.id) { index, command in
+                        ForEach(Array(commands.enumerated()), id: \.element.id) { index, command in
                             SlashCommandRow(
                                 command: command,
                                 isSelected: index == selectedIndex