1 files changed, 27 insertions, 12 deletions

diff --git a/DomainDig/SweepActivityController.swift b/DomainDig/SweepActivityController.swift
index a00bb2f..e6d179e 100644
--- a/DomainDig/SweepActivityController.swift
+++ b/DomainDig/SweepActivityController.swift
@@ -2,11 +2,18 @@ import ActivityKit
 import Foundation
 
 /// Starts, updates, and ends the sweep Live Activity around a batch run.
+///
+/// Holds the activity's `id` (a Sendable `String`) rather than the
+/// `Activity` object itself. `Activity` is not Sendable, and sending the
+/// stored reference into the fire-and-forget update task while `self` still
+/// held it was a Swift 6 region-isolation violation (issue #27). Each task
+/// re-resolves the activity via `Activity.activities`, ActivityKit's
+/// sanctioned lookup, so nothing non-Sendable crosses an isolation boundary.
 @MainActor
 final class SweepActivityController {
     static let shared = SweepActivityController()
 
-    private var activity: Activity<SweepActivityAttributes>?
+    private var activityID: String?
 
     private init() { /* Singleton; use the shared instance. */ }
 
@@ -23,14 +30,15 @@ final class SweepActivityController {
             changed: 0,
             warnings: 0
         )
-        activity = try? Activity.request(
+        let activity = try? Activity.request(
             attributes: SweepActivityAttributes(title: title, startedAt: Date()),
             content: ActivityContent(state: state, staleDate: nil)
         )
+        activityID = activity?.id
     }
 
     func update(completed: Int, total: Int, currentDomain: String?) {
-        guard let activity else { return }
+        guard let activityID else { return }
         let state = SweepActivityAttributes.ContentState(
             completed: completed,
             total: total,
@@ -39,25 +47,32 @@ final class SweepActivityController {
             warnings: 0
         )
         Task {
+            guard let activity = Self.activity(withID: activityID) else { return }
             await activity.update(ActivityContent(state: state, staleDate: nil))
         }
     }
 
     func end(changed: Int, warnings: Int, immediately: Bool = false) {
-        guard let activity else { return }
-        self.activity = nil
-        let state = SweepActivityAttributes.ContentState(
-            completed: activity.content.state.total,
-            total: activity.content.state.total,
-            currentDomain: nil,
-            changed: changed,
-            warnings: warnings
-        )
+        guard let activityID else { return }
+        self.activityID = nil
         Task {
+            guard let activity = Self.activity(withID: activityID) else { return }
+            let total = activity.content.state.total
+            let state = SweepActivityAttributes.ContentState(
+                completed: total,
+                total: total,
+                currentDomain: nil,
+                changed: changed,
+                warnings: warnings
+            )
             await activity.end(
                 ActivityContent(state: state, staleDate: nil),
                 dismissalPolicy: immediately ? .immediate : .after(Date().addingTimeInterval(60))
             )
         }
     }
+
+    private nonisolated static func activity(withID id: String) -> Activity<SweepActivityAttributes>? {
+        Activity<SweepActivityAttributes>.activities.first { $0.id == id }
+    }
 }