Fix focus-on-scroll and harden reload scripts

Sources/Update/UpdateLogStore.swift

@@ -63,3 +63,66 @@ final class UpdateLogStore {
         }
     }
 }
+
+final class FocusLogStore {
+    static let shared = FocusLogStore()
+
+    private let queue = DispatchQueue(label: "cmuxterm.focus.log")
+    private var entries: [String] = []
+    private let maxEntries = 400
+    private let logURL: URL
+    private let formatter: ISO8601DateFormatter
+
+    private init() {
+        formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        let logsDir = FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask).first
+            ?? FileManager.default.temporaryDirectory
+        logURL = logsDir.appendingPathComponent("Logs/cmuxterm-focus.log")
+        ensureLogFile()
+    }
+
+    func append(_ message: String) {
+        #if DEBUG
+        let timestamp = formatter.string(from: Date())
+        let line = "[\(timestamp)] \(message)"
+        queue.async { [weak self] in
+            guard let self else { return }
+            entries.append(line)
+            if entries.count > maxEntries {
+                entries.removeFirst(entries.count - maxEntries)
+            }
+            appendToFile(line: line)
+        }
+        #endif
+    }
+
+    func snapshot() -> String {
+        queue.sync {
+            entries.joined(separator: "\n")
+        }
+    }
+
+    func logPath() -> String {
+        logURL.path
+    }
+
+    private func ensureLogFile() {
+        let directory = logURL.deletingLastPathComponent()
+        try? FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+        if !FileManager.default.fileExists(atPath: logURL.path) {
+            try? Data().write(to: logURL)
+        }
+    }
+
+    private func appendToFile(line: String) {
+        let data = Data((line + "\n").utf8)
+        if let handle = try? FileHandle(forWritingTo: logURL) {
+            try? handle.seekToEnd()
+            try? handle.write(contentsOf: data)
+            try? handle.close()
+        } else {
+            try? data.write(to: logURL, options: .atomic)
+        }
+    }
+}