Surface sync failures in Settings via lastSyncError

Claude-Session: https://claude.ai/code/session_01SY5jsAUf4qoPxSvv8xAqXS

Workouts/Sync/SyncEngine.swift

@@ -20,6 +20,10 @@ final class SyncEngine {
     private(set) var iCloudStatus: ICloudStatus = .checking
     private(set) var isSyncing = false
 
+    /// Last non-fatal sync failure, surfaced for the UI to render. Cleared on the
+    /// next successful write or full reconcile.
+    private(set) var lastSyncError: String?
+
     /// Called after the cache changes (local or remote). The watch bridge uses
     /// this to push fresh state to the watch.
     var onCacheChanged: (() -> Void)?
@@ -168,7 +172,7 @@ final class SyncEngine {
                 deleteCachedEntity(jsonRelativePath: path)
             }
         }
-        try? context.save()
+        do { try context.save() } catch { report("Cache save failed", error) }
         onCacheChanged?()
     }
 
@@ -184,7 +188,7 @@ final class SyncEngine {
     func ingestFromWatch(_ doc: WorkoutDocument) async {
         await save(workout: doc)
         CacheMapper.upsertWorkout(doc, relativePath: doc.relativePath, into: context)
-        try? context.save()
+        do { try context.save() } catch { report("Cache save failed", error) }
         onCacheChanged?()
     }
 
@@ -192,15 +196,23 @@ final class SyncEngine {
 
     func save(split doc: SplitDocument) async {
         guard let fm = fileManager else { return }
-        do { try await fm.write(try DocumentCoder.encoder.encode(doc), to: doc.relativePath) }
-        catch { print("[Sync] write failed for \(doc.relativePath): \(error)") }
+        do {
+            try await fm.write(try DocumentCoder.encoder.encode(doc), to: doc.relativePath)
+            lastSyncError = nil
+        } catch {
+            report("Failed to save split", error)
+        }
         // Cache updates reactively via the monitor.
     }
 
     func save(workout doc: WorkoutDocument) async {
         guard let fm = fileManager else { return }
-        do { try await fm.write(try DocumentCoder.encoder.encode(doc), to: doc.relativePath) }
-        catch { print("[Sync] write failed for \(doc.relativePath): \(error)") }
+        do {
+            try await fm.write(try DocumentCoder.encoder.encode(doc), to: doc.relativePath)
+            lastSyncError = nil
+        } catch {
+            report("Failed to save workout", error)
+        }
         // Drive the HealthKit writer: a watch-recorded doc cancels any pending estimate;
         // a completed doc (re)considers an estimate (the writer dedupes on metrics).
         if doc.metrics?.source == .watch { onWatchMetricsArrived?(doc.id) }
@@ -220,8 +232,9 @@ final class SyncEngine {
         let tombstone = Tombstone(id: id, kind: kind, deletedAt: Date())
         do {
             try await fm.writeTombstoneAndRemove(tombstone, livePath: livePath)
+            lastSyncError = nil
         } catch {
-            print("[Sync] delete failed for \(id): \(error)")
+            report("Failed to delete \(id)", error)
         }
     }
 
@@ -237,6 +250,7 @@ final class SyncEngine {
             // treat an unreadable file as absent. The next monitor event or
             // reconcile retries it.
             log.error("import: read failed for \(relativePath, privacy: .public): \(error)")
+            report("Failed to read \(relativePath)", error)
             return
         }
 
@@ -279,6 +293,7 @@ final class SyncEngine {
                 // how evicted records used to vanish on storage-constrained
                 // devices.
                 log.error("reconcile: read failed for \(path, privacy: .public): \(error)")
+                report("Failed to read \(path)", error)
                 unreadablePaths.insert(path)
                 continue
             }
@@ -308,7 +323,14 @@ final class SyncEngine {
                 context.delete(w)
             }
         }
-        try? context.save()
+        do {
+            try context.save()
+            // A fully clean pass supersedes any earlier failure; a pass with
+            // unreadable files keeps its own report visible.
+            if unreadablePaths.isEmpty { lastSyncError = nil }
+        } catch {
+            report("Cache save failed", error)
+        }
         onCacheChanged?()
     }
 
@@ -343,4 +365,14 @@ final class SyncEngine {
             }
         }
     }
+
+    // MARK: - Error Reporting
+
+    /// Record a non-fatal sync failure: log it and publish it as `lastSyncError`
+    /// for the UI to render. Replaces silent `try?` / print-only handling.
+    private func report(_ message: String, _ error: Error? = nil) {
+        let full = error.map { "\(message): \($0.localizedDescription)" } ?? message
+        print("[Sync] \(full)")
+        lastSyncError = full
+    }
 }