Watch: review fixes for action errors that vanished, feed refreshes dropped or overwritten around a change, a fresh thread screen per route, errors cleared on sign out, notification actions only while paired, cache writes off the main thread and capped at 30 threads, Ask before acting and Load earlier races, two-letter search, C# headings, and strictly encoded query values

watch/WristCode/FeedCache.swift

@@ -1,11 +1,13 @@
-// The last good feed, and the last detail of each thread opened, saved as JSON in the app's caches
-// folder. Launch shows them at once while the first refresh runs. Signing out clears them, and demo
-// mode never reads or writes them.
+// The last good feed, and the last detail of the 30 threads saved most recently, saved as JSON in
+// the app's caches folder. Launch shows them at once while the first refresh runs. Signing out clears
+// them, and demo mode never reads or writes them.
 
 import Foundation
 
 struct FeedCache: Sendable {
     let directory: URL
+    /// How many thread details are kept. Saving one more deletes the oldest.
+    var threadLimit = 30
 
     static let standard = FeedCache(directory: .cachesDirectory.appending(path: "WristCode", directoryHint: .isDirectory))
 
@@ -23,6 +25,20 @@ struct FeedCache: Sendable {
 
     func save(_ detail: ThreadDetail) {
         write(detail, Self.threadFile(detail.item.hostId, detail.item.threadId))
+        pruneThreads()
+    }
+
+    /// Deletes the thread details saved longest ago, past `threadLimit`.
+    private func pruneThreads() {
+        let fileManager = FileManager.default
+        let key = URLResourceKey.contentModificationDateKey
+        guard let files = try? fileManager.contentsOfDirectory(at: directory, includingPropertiesForKeys: [key]) else { return }
+        let threads = files.filter { $0.lastPathComponent.hasPrefix("thread-") }
+        guard threads.count > threadLimit else { return }
+        let modified = { (url: URL) in (try? url.resourceValues(forKeys: [key]).contentModificationDate) ?? .distantPast }
+        for url in threads.sorted(by: { modified($0) > modified($1) }).dropFirst(threadLimit) {
+            try? fileManager.removeItem(at: url)
+        }
     }
 
     /// Deletes everything saved, as when the watch unpairs.