Mac: finish Moltbot rename

apps/macos/Sources/Moltbot/CanvasFileWatcher.swift

@@ -0,0 +1,94 @@
+import CoreServices
+import Foundation
+
+final class CanvasFileWatcher: @unchecked Sendable {
+    private let url: URL
+    private let queue: DispatchQueue
+    private var stream: FSEventStreamRef?
+    private var pending = false
+    private let onChange: () -> Void
+
+    init(url: URL, onChange: @escaping () -> Void) {
+        self.url = url
+        self.queue = DispatchQueue(label: "bot.molt.canvaswatcher")
+        self.onChange = onChange
+    }
+
+    deinit {
+        self.stop()
+    }
+
+    func start() {
+        guard self.stream == nil else { return }
+
+        let retainedSelf = Unmanaged.passRetained(self)
+        var context = FSEventStreamContext(
+            version: 0,
+            info: retainedSelf.toOpaque(),
+            retain: nil,
+            release: { pointer in
+                guard let pointer else { return }
+                Unmanaged<CanvasFileWatcher>.fromOpaque(pointer).release()
+            },
+            copyDescription: nil)
+
+        let paths = [self.url.path] as CFArray
+        let flags = FSEventStreamCreateFlags(
+            kFSEventStreamCreateFlagFileEvents |
+                kFSEventStreamCreateFlagUseCFTypes |
+                kFSEventStreamCreateFlagNoDefer)
+
+        guard let stream = FSEventStreamCreate(
+            kCFAllocatorDefault,
+            Self.callback,
+            &context,
+            paths,
+            FSEventStreamEventId(kFSEventStreamEventIdSinceNow),
+            0.05,
+            flags)
+        else {
+            retainedSelf.release()
+            return
+        }
+
+        self.stream = stream
+        FSEventStreamSetDispatchQueue(stream, self.queue)
+        if FSEventStreamStart(stream) == false {
+            self.stream = nil
+            FSEventStreamSetDispatchQueue(stream, nil)
+            FSEventStreamInvalidate(stream)
+            FSEventStreamRelease(stream)
+        }
+    }
+
+    func stop() {
+        guard let stream = self.stream else { return }
+        self.stream = nil
+        FSEventStreamStop(stream)
+        FSEventStreamSetDispatchQueue(stream, nil)
+        FSEventStreamInvalidate(stream)
+        FSEventStreamRelease(stream)
+    }
+}
+
+extension CanvasFileWatcher {
+    private static let callback: FSEventStreamCallback = { _, info, numEvents, _, eventFlags, _ in
+        guard let info else { return }
+        let watcher = Unmanaged<CanvasFileWatcher>.fromOpaque(info).takeUnretainedValue()
+        watcher.handleEvents(numEvents: numEvents, eventFlags: eventFlags)
+    }
+
+    private func handleEvents(numEvents: Int, eventFlags: UnsafePointer<FSEventStreamEventFlags>?) {
+        guard numEvents > 0 else { return }
+        guard eventFlags != nil else { return }
+
+        // Coalesce rapid changes (common during builds/atomic saves).
+        if self.pending { return }
+        self.pending = true
+        self.queue.asyncAfter(deadline: .now() + 0.12) { [weak self] in
+            guard let self else { return }
+            self.pending = false
+            self.onChange()
+        }
+    }
+}