2 files changed, 28 insertions, 6 deletions
diff --git a/Hutch/Views/Home/HomeViewModel.swift b/Hutch/Views/Home/HomeViewModel.swift
index 98dd968..a3aed30 100644
--- a/Hutch/Views/Home/HomeViewModel.swift
+++ b/Hutch/Views/Home/HomeViewModel.swift
@@ -819,6 +819,14 @@ final class HomeViewModel {
         var cursor: String?
         var unreadThreads: [InboxThreadSummary] = []
 
+        // thread.updated is the root email's insert time and never advances when a
+        // reply lands, so activity has to come from the list's mail feed.
+        let activity = await MailingListActivityLoader.load(
+            client: client,
+            listRID: mailingList.rid,
+            since: InboxReadStateStore.baseline(defaults: defaults) ?? .distantPast
+        )
+
         while true {
             var variables: [String: any Sendable] = ["rid": mailingList.rid]
             if let cursor {
@@ -838,6 +846,7 @@ final class HomeViewModel {
             let response = cached.value
 
             let unreadThreadSummaries = response.list.threads.results.compactMap { thread -> InboxThreadSummary? in
+                let lastActivityAt = activity.lastActivity(rootEmailID: thread.root.id, fallback: thread.updated)
                 let summary = InboxThreadSummary(
                     rootEmailID: thread.root.id,
                     rootMessageID: thread.root.messageID,
@@ -849,13 +858,13 @@ final class HomeViewModel {
                     listOwner: mailingList.owner,
                     subject: thread.subject,
                     latestSender: thread.sender,
-                    lastActivityAt: thread.updated,
+                    lastActivityAt: lastActivityAt,
                     messageCount: thread.replies + 1,
                     repo: InboxThreadUtilities.deriveRepositoryName(from: mailingList.name),
                     containsPatch: thread.root.patch != nil || thread.subject.localizedCaseInsensitiveContains("[patch"),
                     isUnread: InboxReadStateStore.isUnread(
                         threadID: "\(mailingList.rid)#\(InboxThreadSummary.normalizationKey(for: thread.subject))",
-                        lastActivityAt: thread.updated,
+                        lastActivityAt: lastActivityAt,
                         defaults: defaults
                     )
                 )
diff --git a/Hutch/Views/Projects/ProjectMailingListView.swift b/Hutch/Views/Projects/ProjectMailingListView.swift
index d466121..e4c9df4 100644
--- a/Hutch/Views/Projects/ProjectMailingListView.swift
+++ b/Hutch/Views/Projects/ProjectMailingListView.swift
@@ -84,8 +84,14 @@ final class MailingListDetailViewModel {
                 responseType: ProjectMailingListThreadsResponse.self
             )
 
+            let activity = await MailingListActivityLoader.load(
+                client: client,
+                listRID: mailingList.rid,
+                since: InboxReadStateStore.baseline(defaults: defaults) ?? .distantPast
+            )
+
             threads = deduplicateThreads(
-                response.list.threads.results.map(makeSummary(from:))
+                response.list.threads.results.map { makeSummary(from: $0, activity: activity) }
             )
         } catch {
             self.error = "Failed to load mailing list"
@@ -138,7 +144,10 @@ final class MailingListDetailViewModel {
         NeedsAttentionSnapshotStore.adjustUnreadInboxThreads(by: -unreadThreads.count, accountID: accountID)
     }
 
-    private func makeSummary(from thread: ProjectMailingListThreadPayload) -> InboxThreadSummary {
+    private func makeSummary(
+        from thread: ProjectMailingListThreadPayload,
+        activity: MailingListActivity
+    ) -> InboxThreadSummary {
         let normalizedSubject = thread.subject
             .replacingOccurrences(of: #"\s+"#, with: " ", options: .regularExpression)
             .trimmingCharacters(in: .whitespacesAndNewlines)
@@ -146,6 +155,10 @@ final class MailingListDetailViewModel {
             .lowercased()
         let threadID = "\(mailingList.rid)#\(normalizedSubject)"
 
+        // thread.updated is the root email's insert time and never advances when a
+        // reply lands, so activity has to come from the list's mail feed.
+        let lastActivityAt = activity.lastActivity(rootEmailID: thread.root.id, fallback: thread.updated)
+
         return InboxThreadSummary(
             rootEmailID: thread.root.id,
             rootMessageID: thread.root.messageID,
@@ -157,11 +170,11 @@ final class MailingListDetailViewModel {
             listOwner: mailingList.owner,
             subject: thread.subject,
             latestSender: thread.sender,
-            lastActivityAt: thread.updated,
+            lastActivityAt: lastActivityAt,
             messageCount: thread.replies + 1,
             repo: nil,
             containsPatch: thread.root.patch != nil || thread.subject.localizedCaseInsensitiveContains("[patch"),
-            isUnread: InboxReadStateStore.isUnread(threadID: threadID, lastActivityAt: thread.updated, defaults: defaults)
+            isUnread: InboxReadStateStore.isUnread(threadID: threadID, lastActivityAt: lastActivityAt, defaults: defaults)
         )
     }