fix(agent): freeze elapsed timer after completion

Glint/Agent/AgentPaneSummary.swift

@@ -58,6 +58,13 @@ func agentElapsedLabel(since start: Date, now: Date) -> String {
     return "\(total / 3600)h\((total % 3600) / 60)m"
 }
 
+/// Busy panes advance against the live clock. Attention states that end or
+/// pause the turn keep the duration captured by their last hook instead of
+/// making a completed/error/reply-wait row look as if it were still running.
+func agentElapsedReferenceDate(status: PaneAgentStatus, updatedAt: Date, now: Date) -> Date {
+    WorkspaceStore.isBusyStatus(status) ? now : updatedAt
+}
+
 // MARK: - Cluster (always-visible glance layer)
 
 /// Up to `cap` attention-sorted status dots — one per live agent pane. This
@@ -176,7 +183,14 @@ private struct PaneSummaryRow: View {
                 )
 
             TimelineView(.periodic(from: .now, by: 1)) { ctx in
-                Text(agentElapsedLabel(since: info.since, now: ctx.date))
+                Text(agentElapsedLabel(
+                    since: info.since,
+                    now: agentElapsedReferenceDate(
+                        status: info.status,
+                        updatedAt: info.updatedAt,
+                        now: ctx.date
+                    )
+                ))
                     .font(.system(size: 10, weight: .medium, design: .monospaced))
                     .foregroundStyle(Theme.text4)
                     .lineLimit(1)

Glint/Workspace/WorkspaceStore.swift

@@ -4289,6 +4289,8 @@ extension WorkspaceStore {
         let status: PaneAgentStatus
         /// Turn start — drives the "2m" elapsed label (total turn time).
         let since: Date
+        /// Last hook time — freezes the elapsed label once the turn stops.
+        let updatedAt: Date
         var id: PaneID { paneID }
     }
 
@@ -4304,7 +4306,8 @@ extension WorkspaceStore {
             guard let e = paneAgentState[key], e.status != .idle else { continue }
             out.append((AgentPaneInfo(paneID: item.pane, number: idx + 1,
                                       label: item.label, kind: e.kind,
-                                      status: e.status, since: e.turnStartedAt),
+                                      status: e.status, since: e.turnStartedAt,
+                                      updatedAt: e.updatedAt),
                         e.updatedAt))
         }
         out.sort {
@@ -4337,7 +4340,7 @@ extension WorkspaceStore {
     /// A turn is actively running in these states — used to anchor the turn
     /// clock (set on the first non-busy → busy transition, kept through the
     /// turn). `.justCompleted`/`.failed`/`.idle` are turn-end / no-turn.
-    static func isBusyStatus(_ s: PaneAgentStatus) -> Bool {
+    nonisolated static func isBusyStatus(_ s: PaneAgentStatus) -> Bool {
         switch s {
         case .thinking, .tool, .compacting, .needsPermission: return true
         case .justCompleted, .failed, .needsReply, .idle:     return false

GlintTests/AgentHookRoutingTests.swift

@@ -2,6 +2,24 @@ import XCTest
 @testable import Glint
 
 final class AgentHookRoutingTests: XCTestCase {
+    func testCompletedAgentElapsedTimerStopsAtCompletion() {
+        let completedAt = Date(timeIntervalSince1970: 125)
+        let muchLater = Date(timeIntervalSince1970: 900)
+
+        XCTAssertEqual(
+            agentElapsedReferenceDate(status: .justCompleted,
+                                      updatedAt: completedAt,
+                                      now: muchLater),
+            completedAt
+        )
+        XCTAssertEqual(
+            agentElapsedReferenceDate(status: .thinking,
+                                      updatedAt: completedAt,
+                                      now: muchLater),
+            muchLater
+        )
+    }
+
     func testAttentionRankDoesNotLetThinkingHideCompletedSibling() {
         XCTAssertEqual(
             PaneAgentStatus.bestAttentionRank(in: [.thinking, .justCompleted]),