fix(KAN-71): correct Apple navigation gestures and scroll bounds

native/src-tauri/src/desktop.rs

@@ -177,6 +177,7 @@ fn open_workspace(app: &AppHandle, input: &str) -> Result<(), &'static str> {
             .center()
             .visible(false)
             .data_store_identifier(server.profile)
+            .initialization_script(include_str!("../../ui/workspace-navigation.js"))
             .on_navigation(move |destination| {
                 if !allows_server_navigation(&server_url, destination) {
                     open_external(destination);
@@ -227,6 +228,15 @@ fn open_workspace(app: &AppHandle, input: &str) -> Result<(), &'static str> {
             })
             .build()
             .map_err(|_| "connectionError")?;
+    #[cfg(target_os = "macos")]
+    window
+        .with_webview(|webview| unsafe {
+            unsafe extern "C" {
+                fn install_workspace_navigation(webview: *mut std::ffi::c_void);
+            }
+            install_workspace_navigation(webview.inner().cast());
+        })
+        .map_err(|_| "connectionError")?;
     let handle = app.clone();
     window.on_window_event(move |event| {
         if let WindowEvent::CloseRequested { api, .. } = event {

native/src-tauri/src/navigation.m

@@ -0,0 +1,102 @@
+#import <AppKit/AppKit.h>
+#import <WebKit/WebKit.h>
+#import <objc/runtime.h>
+
+// Keep AppKit's system swipe preferences and cancellation thresholds, but use
+// script history traversal so asynchronously created Inertia entries aren't skipped.
+@interface KanbanNavigation : NSObject
+@property(nonatomic, weak) WKWebView *webview;
+@property(nonatomic, strong) id monitor;
+@property(nonatomic) BOOL pending;
+@property(nonatomic) BOOL tracking;
+@property(nonatomic) BOOL blocked;
+@property(nonatomic) NSUInteger sequence;
+@end
+
+@implementation KanbanNavigation
+- (BOOL)swipeTrackingEnabled {
+    return NSEvent.isSwipeTrackingFromScrollEventsEnabled;
+}
+
+- (void)dealloc {
+    if (_monitor) [NSEvent removeMonitor:_monitor];
+}
+
+- (NSEvent *)handleEvent:(NSEvent *)event {
+    WKWebView *webview = self.webview;
+    if (!webview || event.window != webview.window || !webview.window.isKeyWindow ||
+        webview.hidden || ![self swipeTrackingEnabled]) return event;
+    if (event.phase == NSEventPhaseBegan) {
+        self.sequence++;
+        self.blocked = NO;
+        self.pending = NO;
+        self.tracking = NO;
+    }
+    if (self.tracking) return nil;
+    if (event.phase == NSEventPhaseEnded || event.phase == NSEventPhaseCancelled) {
+        self.sequence++;
+        self.pending = NO;
+        return event;
+    }
+    if (self.blocked || self.pending || event.momentumPhase != NSEventPhaseNone ||
+        !(event.phase & (NSEventPhaseBegan | NSEventPhaseChanged)) || !event.hasPreciseScrollingDeltas) return event;
+    if (fabs(event.scrollingDeltaX) <= fabs(event.scrollingDeltaY)) {
+        if (fabs(event.scrollingDeltaY) > 0) self.blocked = YES;
+        return event;
+    }
+    NSPoint point = [webview convertPoint:event.locationInWindow fromView:nil];
+    if (!NSPointInRect(point, webview.bounds)) return event;
+    if (!webview.isFlipped) point.y = webview.bounds.size.height - point.y;
+    NSString *script = [NSString stringWithFormat:@"window.__kanbanNavigation?.canSwipe(%f, %f) === true", point.x, point.y];
+    self.pending = YES;
+    NSUInteger sequence = self.sequence;
+    NSURL *page = webview.URL;
+    __weak KanbanNavigation *weakSelf = self;
+    [webview evaluateJavaScript:script completionHandler:^(id allowed, NSError *error) {
+        KanbanNavigation *owner = weakSelf;
+        if (!owner || owner.sequence != sequence) return;
+        owner.pending = NO;
+        owner.blocked = YES;
+        if (error || ![allowed isEqual:@YES] || ![webview.URL isEqual:page] ||
+            (!webview.canGoBack && !webview.canGoForward)) return;
+        owner.tracking = YES;
+        [event trackSwipeEventWithOptions:NSEventSwipeTrackingLockDirection | NSEventSwipeTrackingClampGestureAmount
+                dampenAmountThresholdMin:webview.canGoForward ? -1 : 0
+                                    max:webview.canGoBack ? 1 : 0
+                           usingHandler:^(CGFloat amount, NSEventPhase phase, BOOL complete, BOOL *stop) {
+            KanbanNavigation *current = weakSelf;
+            if (current.sequence != sequence) {
+                *stop = YES;
+                return;
+            }
+            if (!current || !webview.window.isKeyWindow || ![webview.URL isEqual:page]) {
+                current.tracking = NO;
+                *stop = YES;
+                return;
+            }
+            if (!complete) return;
+            current.tracking = NO;
+            if (phase == NSEventPhaseCancelled) return;
+            NSInteger direction = amount >= 1 ? -1 : amount <= -1 ? 1 : 0;
+            if ((direction == -1 && webview.canGoBack) || (direction == 1 && webview.canGoForward)) {
+                NSString *navigate = [NSString stringWithFormat:@"if (%@) window.__kanbanNavigation.step(%ld)", script, (long)direction];
+                [webview evaluateJavaScript:navigate completionHandler:nil];
+            }
+        }];
+    }];
+    return event;
+}
+@end
+
+void install_workspace_navigation(void *pointer) {
+    WKWebView *webview = (__bridge WKWebView *)pointer;
+    webview.allowsBackForwardNavigationGestures = NO;
+    KanbanNavigation *navigation = [KanbanNavigation new];
+    navigation.webview = webview;
+    __weak KanbanNavigation *weakNavigation = navigation;
+    navigation.monitor = [NSEvent addLocalMonitorForEventsMatchingMask:NSEventMaskScrollWheel handler:^NSEvent *(NSEvent *event) {
+        KanbanNavigation *owner = weakNavigation;
+        return owner ? [owner handleEvent:event] : event;
+    }];
+    objc_setAssociatedObject(webview, @selector(handleEvent:), navigation, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}