fix(hig): show the resize cursor over SwiftUI-hosted split dividers

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Fixed split view dividers not showing the resize cursor on hover in the Users and Roles, Structure, Server Dashboard, and SQL editor panels, even though the dividers could be dragged. (#1905)
 - Fixed a query with a comment after the closing semicolon, such as `SELECT 1; -- note`, being run as two statements, with the trailing comment sent to the server as a failing second statement. Running a comment-only query or selection now does nothing instead of producing a server error, and AI and MCP clients are no longer told such a query is multi-statement. (#1895)
 - Fixed duplicating a connection dropping its Cloudflare Tunnel and Cloud SQL Auth Proxy settings and stored secrets.
 - Fixed the tunnel panes warning about only some of the other enabled connection methods. Each pane now lists every conflicting method with a button to turn it off.

CLAUDE.md

@@ -167,6 +167,8 @@ These have caused real bugs when violated:
 
 **Tab content must never pin the window's split dividers**: `NSSplitViewItem.minimumThickness` is a required constraint, so a nested `NSSplitViewController` reports `sum(minimums) + dividers` as its `fittingSize`. SwiftUI adopts that number for an `NSViewControllerRepresentable` and the enclosing `NSHostingView` turns it into a `minWidth` at priority 999.9, which beats the 490 (`dragThatCannotResizeWindow`) a divider drag runs at: the window's sidebar and inspector dividers go dead. Two rules follow. First, every hosting controller that is a split item's view controller sets `sizingOptions = []` (`MainSplitViewController`'s `detailHosting` and `inspectorHosting`, and both panes inside `AutosavingSplitView`), and `AutosavingSplitView` returns the proposal from `sizeThatFits` so its own minimums never escape into SwiftUI. Second, a tab that genuinely needs more width than `defaultDetailMinThickness` declares it through `resolveDetailMinimumThickness(for:)` instead of leaking it; the detail pane's minimum is a per-tab contract, and `recomputeWindowMinSize()` reads it live. AppKit will not rescue you here: `.sidebar` behaviour and `canCollapseFromWindowResize` only auto-collapse on a window live-resize, which an embedded split view never sees, and no form of collapsibility lowers `fittingSize` (only an actual `isCollapsed = true` does). `CollapsingSplitViewController` collapses the pane itself for that reason. This shipped as a dead inspector divider on Users & Roles tabs (#1872).
 
+**A SwiftUI-hosted split view needs an explicit divider cursor**: `NSSplitView` shows the resize cursor over its dividers through AppKit's cursor-rects system, which does not fire once the split view is mounted inside an `NSHostingController` (every tab-content split is, several SwiftUI layers deep under `MainSplitViewController.detailHosting`). The divider still drags because drag hit-testing is independent of cursor rects, but the pointer never changes. Every SwiftUI-hosted split-view controller must subclass `ResizeCursorSplitViewController`, which adds a key-window tracking area to its own split view and sets `NSCursor.columnResize`/`rowResize` (falling back to `resizeLeftRight`/`resizeUpDown` before macOS 15) in `mouseMoved`, the same hand-rolled approach `SortableHeaderView` uses for column resize. It attaches the tracking area to the framework's split view in `viewDidLoad` rather than replacing the split view, so `NSSplitViewController`'s own layout and divider orientation stay intact; replacing the split view through a `loadView` override that skips `super` leaves the controller half-initialized and its panes stack instead of laying out side by side. Do not swap the controller back to a plain `NSSplitViewController` expecting the stock cursor to work; the window's own sidebar and inspector dividers only get the cursor for free because `MainSplitViewController` is the window's `contentViewController` directly, with no SwiftUI host in between. This shipped as Users & Roles, Structure, Server Dashboard, and query editor dividers that dragged but never showed the resize cursor (#1905).
+
 ### Main Coordinator Pattern
 
 `MainContentCoordinator` is the central coordinator, split across 7+ extension files in `Views/Main/Extensions/` (e.g., `+Alerts`, `+Filtering`, `+Pagination`, `+RowOperations`). When adding coordinator functionality, add a new extension file rather than growing the main file.

TablePro/Views/Components/AutosavingSplitView.swift

@@ -86,7 +86,7 @@ struct AutosavingSplitView<Primary: View, Secondary: View>: NSViewControllerRepr
 }
 
 @MainActor
-internal final class CollapsingSplitViewController: NSSplitViewController {
+internal final class CollapsingSplitViewController: ResizeCursorSplitViewController {
     var collapsesPrimaryWhenTight = false
 
     private var didAutoCollapsePrimary = false

TablePro/Views/Components/ResizeCursorSplitViewController.swift

@@ -0,0 +1,119 @@
+//
+//  ResizeCursorSplitViewController.swift
+//  TablePro
+//
+
+import AppKit
+
+internal enum SplitDividerCursorGeometry {
+    static func dividerHitRects(
+        subviewFrames: [CGRect],
+        collapsed: [Bool],
+        isVertical: Bool,
+        padding: CGFloat,
+        bounds: CGRect
+    ) -> [CGRect] {
+        guard subviewFrames.count == collapsed.count, subviewFrames.count >= 2 else { return [] }
+
+        var rects: [CGRect] = []
+        for index in 0..<(subviewFrames.count - 1) where !collapsed[index] && !collapsed[index + 1] {
+            let first = subviewFrames[index]
+            let second = subviewFrames[index + 1]
+            if isVertical {
+                let (start, end) = gap(first.minX, first.maxX, second.minX, second.maxX)
+                rects.append(
+                    CGRect(
+                        x: start - padding,
+                        y: bounds.minY,
+                        width: end - start + padding * 2,
+                        height: bounds.height
+                    )
+                )
+            } else {
+                let (start, end) = gap(first.minY, first.maxY, second.minY, second.maxY)
+                rects.append(
+                    CGRect(
+                        x: bounds.minX,
+                        y: start - padding,
+                        width: bounds.width,
+                        height: end - start + padding * 2
+                    )
+                )
+            }
+        }
+        return rects
+    }
+
+    static func isWithinDivider(point: CGPoint, hitRects: [CGRect]) -> Bool {
+        hitRects.contains { $0.contains(point) }
+    }
+
+    private static func gap(
+        _ firstMin: CGFloat,
+        _ firstMax: CGFloat,
+        _ secondMin: CGFloat,
+        _ secondMax: CGFloat
+    ) -> (start: CGFloat, end: CGFloat) {
+        firstMax <= secondMin ? (firstMax, secondMin) : (secondMax, firstMin)
+    }
+}
+
+@MainActor
+internal class ResizeCursorSplitViewController: NSSplitViewController {
+    private static let hitPadding: CGFloat = 3
+
+    private var isShowingResizeCursor = false
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        let area = NSTrackingArea(
+            rect: .zero,
+            options: [.activeInKeyWindow, .mouseMoved, .mouseEnteredAndExited, .inVisibleRect],
+            owner: self,
+            userInfo: nil
+        )
+        splitView.addTrackingArea(area)
+    }
+
+    override func mouseMoved(with event: NSEvent) {
+        let point = splitView.convert(event.locationInWindow, from: nil)
+        guard isWithinDivider(point) else {
+            restoreCursorIfNeeded()
+            super.mouseMoved(with: event)
+            return
+        }
+        resizeCursor.set()
+        isShowingResizeCursor = true
+    }
+
+    override func mouseExited(with event: NSEvent) {
+        restoreCursorIfNeeded()
+        super.mouseExited(with: event)
+    }
+
+    private func restoreCursorIfNeeded() {
+        guard isShowingResizeCursor else { return }
+        NSCursor.arrow.set()
+        isShowingResizeCursor = false
+    }
+
+    private func isWithinDivider(_ point: CGPoint) -> Bool {
+        let hitRects = SplitDividerCursorGeometry.dividerHitRects(
+            subviewFrames: splitView.subviews.map(\.frame),
+            collapsed: splitView.subviews.map { splitView.isSubviewCollapsed($0) },
+            isVertical: splitView.isVertical,
+            padding: Self.hitPadding,
+            bounds: splitView.bounds
+        )
+        return SplitDividerCursorGeometry.isWithinDivider(point: point, hitRects: hitRects)
+    }
+
+    private var resizeCursor: NSCursor {
+        if #available(macOS 15.0, *) {
+            return splitView.isVertical
+                ? .columnResize(directions: [.left, .right])
+                : .rowResize(directions: [.up, .down])
+        }
+        return splitView.isVertical ? .resizeLeftRight : .resizeUpDown
+    }
+}

TablePro/Views/Editor/QuerySplitView.swift

@@ -12,7 +12,7 @@ struct QuerySplitView<TopContent: View, BottomContent: View>: NSViewControllerRe
     }
 
     func makeNSViewController(context: Context) -> NSSplitViewController {
-        let splitViewController = NSSplitViewController()
+        let splitViewController = ResizeCursorSplitViewController()
         splitViewController.splitView.isVertical = false
         splitViewController.splitView.dividerStyle = .thin
         splitViewController.splitView.autosaveName = autosaveName

TablePro/Views/ServerDashboard/ServerDashboardSplitView.swift

@@ -9,7 +9,7 @@ struct ServerDashboardSplitView: NSViewControllerRepresentable {
     }
 
     func makeNSViewController(context: Context) -> NSSplitViewController {
-        let splitViewController = NSSplitViewController()
+        let splitViewController = ResizeCursorSplitViewController()
         splitViewController.splitView.isVertical = false
         splitViewController.splitView.dividerStyle = .thin
         splitViewController.splitView.autosaveName = "ServerDashboardSplit"

TableProTests/Views/Components/SplitDividerCursorGeometryTests.swift

@@ -0,0 +1,93 @@
+import AppKit
+import Foundation
+@testable import TablePro
+import Testing
+
+@Suite("Split divider cursor geometry")
+@MainActor
+struct SplitDividerCursorGeometryTests {
+    @Test("A vertical split places one padded, full-height rect over the divider")
+    func verticalSplitProducesOneRect() {
+        let rects = SplitDividerCursorGeometry.dividerHitRects(
+            subviewFrames: [
+                CGRect(x: 0, y: 0, width: 150, height: 200),
+                CGRect(x: 151, y: 0, width: 149, height: 200)
+            ],
+            collapsed: [false, false],
+            isVertical: true,
+            padding: 3,
+            bounds: CGRect(x: 0, y: 0, width: 300, height: 200)
+        )
+        #expect(rects == [CGRect(x: 147, y: 0, width: 7, height: 200)])
+    }
+
+    @Test("A horizontal split places one padded, full-width rect over the divider")
+    func horizontalSplitProducesOneRect() {
+        let rects = SplitDividerCursorGeometry.dividerHitRects(
+            subviewFrames: [
+                CGRect(x: 0, y: 0, width: 200, height: 150),
+                CGRect(x: 0, y: 151, width: 200, height: 149)
+            ],
+            collapsed: [false, false],
+            isVertical: false,
+            padding: 3,
+            bounds: CGRect(x: 0, y: 0, width: 200, height: 300)
+        )
+        #expect(rects == [CGRect(x: 0, y: 147, width: 200, height: 7)])
+    }
+
+    @Test("Three panes produce two dividers")
+    func threePanesProduceTwoDividers() {
+        let rects = SplitDividerCursorGeometry.dividerHitRects(
+            subviewFrames: [
+                CGRect(x: 0, y: 0, width: 150, height: 200),
+                CGRect(x: 151, y: 0, width: 150, height: 200),
+                CGRect(x: 302, y: 0, width: 159, height: 200)
+            ],
+            collapsed: [false, false, false],
+            isVertical: true,
+            padding: 3,
+            bounds: CGRect(x: 0, y: 0, width: 461, height: 200)
+        )
+        #expect(rects == [
+            CGRect(x: 147, y: 0, width: 7, height: 200),
+            CGRect(x: 298, y: 0, width: 7, height: 200)
+        ])
+    }
+
+    @Test("A collapsed pane drops the divider next to it")
+    func collapsedPaneDropsAdjacentDivider() {
+        let rects = SplitDividerCursorGeometry.dividerHitRects(
+            subviewFrames: [
+                CGRect(x: 0, y: 0, width: 150, height: 200),
+                CGRect(x: 151, y: 0, width: 150, height: 200),
+                CGRect(x: 302, y: 0, width: 159, height: 200)
+            ],
+            collapsed: [false, false, true],
+            isVertical: true,
+            padding: 3,
+            bounds: CGRect(x: 0, y: 0, width: 461, height: 200)
+        )
+        #expect(rects == [CGRect(x: 147, y: 0, width: 7, height: 200)])
+    }
+
+    @Test("Fewer than two panes produce no dividers")
+    func singlePaneProducesNoDividers() {
+        let rects = SplitDividerCursorGeometry.dividerHitRects(
+            subviewFrames: [CGRect(x: 0, y: 0, width: 300, height: 200)],
+            collapsed: [false],
+            isVertical: true,
+            padding: 3,
+            bounds: CGRect(x: 0, y: 0, width: 300, height: 200)
+        )
+        #expect(rects.isEmpty)
+    }
+
+    @Test("A point inside the divider is detected, one outside is not")
+    func hitTestingMatchesTheDividerRect() {
+        let hitRects = [CGRect(x: 147, y: 0, width: 7, height: 200)]
+        #expect(SplitDividerCursorGeometry.isWithinDivider(point: CGPoint(x: 150, y: 100), hitRects: hitRects))
+        #expect(!SplitDividerCursorGeometry.isWithinDivider(point: CGPoint(x: 100, y: 100), hitRects: hitRects))
+        #expect(!SplitDividerCursorGeometry.isWithinDivider(point: CGPoint(x: 200, y: 100), hitRects: hitRects))
+    }
+}