feat(chat): show active-project indicator in SessionInfoBar + nav title

Adds a visible cue telling the user when their chat is scoped to
a Scarf project. Two surfaces:

- **SessionInfoBar** gets a folder-fill icon + project name chip at
  the start of the bar (before the working dot + title). Rendered
  with `.tint` foregroundStyle so it's visually anchored as the
  first piece of context. Hidden for non-project chats — the bar
  looks identical to v2.2.1 when projectName is nil.

- **Navigation title** becomes `Chat · <ProjectName>` when scoped,
  stays as plain `Chat` otherwise. Matches macOS conventions for
  "subject — detail" titles.

ChatViewModel gains two `@Observable` properties:

- `currentProjectPath: String?` — absolute path, source of truth
  for attribution lookups
- `currentProjectName: String?` — resolved via the projects
  registry at session-start; stored to avoid disk reads on every
  render. Falls back to the raw path (rather than nil) when a
  session's attribution points at a project no longer in the
  registry — the user still sees *something* rather than silently
  losing the indicator.

Both are populated in `startACPSession(resume:projectPath:)` from
two sources:

1. If the caller passed `projectPath` — fresh project-chat case
2. Otherwise, SessionAttributionService.projectPath(for:
   resolvedSessionId) — resumed-session case. Means clicking an
   old project-attributed session from ANY surface (the project's
   Sessions tab, the global Resume menu) re-surfaces the
   indicator.

When the user starts a non-project session, both fields reset to
nil explicitly so the indicator doesn't leak between chats.

Files:
- ChatViewModel.swift — new properties + resolve logic
- SessionInfoBar.swift — new `projectName: String?` parameter +
  chip rendering
- RichChatView.swift — passes chatViewModel.currentProjectName
  through to SessionInfoBar
- ChatView.swift — navTitle reflects the active project

80/80 Swift tests still pass. Visual change only; no test change.

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

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

@@ -41,6 +41,20 @@ final class ChatViewModel {
     let richChatViewModel: RichChatViewModel
     private var coordinator: Coordinator?
 
+    /// Absolute project path for the current session, when the chat is
+    /// project-scoped (either started via a project's "New Chat" button
+    /// or resumed from a session that was previously attributed via the
+    /// v2.3 sidecar). Nil for plain global chats. Drives the project
+    /// indicator in SessionInfoBar + the `Chat · <Name>` nav title.
+    private(set) var currentProjectPath: String?
+
+    /// Human-readable name of the active project, resolved from the
+    /// projects registry at session-start time. Stored alongside the
+    /// path so the view renders without hitting disk on every update.
+    /// Nil when `currentProjectPath` is nil OR the path isn't in the
+    /// registry (project was removed after the session was attributed).
+    private(set) var currentProjectName: String?
+
     // ACP state
     private var acpClient: ACPClient?
     private var acpEventTask: Task<Void, Never>?
@@ -363,6 +377,37 @@ final class ChatViewModel {
                     )
                 }
 
+                // Resolve which project (if any) this session belongs
+                // to, so SessionInfoBar + nav title can surface it.
+                // Two inputs — use whichever is non-nil:
+                //   * `projectPath` — the caller asked for a project
+                //     scope (fresh project chat). Just-attributed;
+                //     definitely in the sidecar.
+                //   * `attribution.projectPath(for: resolvedSessionId)`
+                //     — the resumed session was previously attributed.
+                //     Covers "click an old project-attributed session
+                //     from the global Sessions sidebar / Resume menu"
+                //     where projectPath isn't known at the call site.
+                let attributedPath = projectPath
+                    ?? attribution.projectPath(for: resolvedSessionId)
+                if let path = attributedPath {
+                    // Look up a human-readable name from the projects
+                    // registry. Missing project (path in the sidecar,
+                    // project since removed) → show the path as a
+                    // fallback label so the chip still renders and the
+                    // user sees *something* rather than silently losing
+                    // the indicator.
+                    let registry = ProjectDashboardService(context: context).loadRegistry()
+                    let name = registry.projects.first(where: { $0.path == path })?.name
+                    self.currentProjectPath = path
+                    self.currentProjectName = name ?? path
+                } else {
+                    // Explicit clear on non-project sessions so the
+                    // indicator doesn't leak from a previous chat.
+                    self.currentProjectPath = nil
+                    self.currentProjectName = nil
+                }
+
                 // Refresh session list so the new ACP session appears in the Resume menu
                 await loadRecentSessions()
 

scarf/scarf/Features/Chat/Views/ChatView.swift

@@ -22,7 +22,13 @@ struct ChatView: View {
         // push the whole window past the screen. Same pattern as
         // the Sessions tab fix in the v2.3 branch.
         .frame(maxWidth: .infinity, maxHeight: .infinity)
-        .navigationTitle("Chat")
+        // v2.3: reflect the active Scarf project in the nav title
+        // so the user can see at a glance that the chat is scoped
+        // (complements the folder chip in SessionInfoBar). Falls
+        // back to the plain "Chat" label for global chats.
+        .navigationTitle(
+            viewModel.currentProjectName.map { "Chat · \($0)" } ?? "Chat"
+        )
         .task {
             await viewModel.loadRecentSessions()
             viewModel.refreshCredentialPreflight()

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

@@ -17,7 +17,13 @@ struct RichChatView: View {
                 isWorking: richChat.isAgentWorking,
                 acpInputTokens: richChat.acpInputTokens,
                 acpOutputTokens: richChat.acpOutputTokens,
-                acpThoughtTokens: richChat.acpThoughtTokens
+                acpThoughtTokens: richChat.acpThoughtTokens,
+                // v2.3: surface the active Scarf project (if any) as
+                // a folder chip at the start of the bar. Driven by
+                // ChatViewModel.currentProjectName which is set in
+                // startACPSession on both new project chats and
+                // resumed project-attributed sessions.
+                projectName: chatViewModel.currentProjectName
             )
             Divider()
 

scarf/scarf/Features/Chat/Views/SessionInfoBar.swift

@@ -7,10 +7,28 @@ struct SessionInfoBar: View {
     var acpInputTokens: Int = 0
     var acpOutputTokens: Int = 0
     var acpThoughtTokens: Int = 0
+    /// Name of the Scarf project this session is attributed to, when
+    /// applicable. Nil for plain global chats. Drives the folder-chip
+    /// indicator rendered before the session title. Resolved by
+    /// `ChatViewModel.currentProjectName` — the view just passes it
+    /// through.
+    var projectName: String? = nil
 
     var body: some View {
         HStack(spacing: 16) {
             if let session {
+                // Project indicator first — visually anchors the session
+                // as "scoped to project X" before the working dot and
+                // title. Hidden for non-project chats so the bar looks
+                // identical to v2.2.1 behavior.
+                if let projectName {
+                    Label(projectName, systemImage: "folder.fill")
+                        .font(.caption)
+                        .foregroundStyle(.tint)
+                        .lineLimit(1)
+                        .help("Chat is scoped to Scarf project \"\(projectName)\"")
+                }
+
                 HStack(spacing: 4) {
                     Circle()
                         .fill(isWorking ? .green : .secondary)