diff --git a/Tests/FloKitTests/CodeBlockPolishTests.swift b/Tests/FloKitTests/CodeBlockPolishTests.swift
index 555a6ef..b92738d 100644
--- a/Tests/FloKitTests/CodeBlockPolishTests.swift
+++ b/Tests/FloKitTests/CodeBlockPolishTests.swift
@@ -185,7 +185,7 @@ extension CodeBlockRenderTests {
     }
 
     /// With the user's substitutions turned on (Edit > Substitutions), prose gets them and code does not.
-    func testCodeGetsNoSubstitutions() {
+    func testCodeGetsNoSubstitutions() throws {
         for (name, doc, isCode) in [("prose", "text", false), ("fenced", "```\ncode", true), ("fenced-closed", "```\ncode\n```", true)] {
             let r = KeyReplayer(width: 1000, height: 600)
             let end = name == "fenced-closed" ? 8 : (doc as NSString).length
@@ -201,7 +201,9 @@ extension CodeBlockRenderTests {
             if isCode {
                 XCTAssertTrue(r.doc.contains(typed), "\(name): typed as is: \(r.doc.debugDescription)")
             } else {
-                XCTAssertFalse(r.doc.contains(typed), "\(name): prose still gets substitutions: \(r.doc.debugDescription)")
+                // Prose is the control. A host with no text checking service (a CI runner) substitutes nothing,
+                // so "code gets none" would pass for no reason. Skip there instead of passing or failing.
+                try XCTSkipIf(r.doc.contains(typed), "this host does not substitute text in prose: \(r.doc.debugDescription)")
             }
             XCTAssertEqual(r.viewText, r.doc, "\(name): view and state agree")
         }
diff --git a/Tests/FloKitTests/CodeBlockRenderTests.swift b/Tests/FloKitTests/CodeBlockRenderTests.swift
index 3e7d32b..ada4ea7 100644
--- a/Tests/FloKitTests/CodeBlockRenderTests.swift
+++ b/Tests/FloKitTests/CodeBlockRenderTests.swift
@@ -67,7 +67,12 @@ final class CodeBlockRenderTests: XCTestCase {
         let tlm = tv.textLayoutManager!
         tlm.ensureLayout(for: tlm.documentRange)
         let rect = tv.visibleRect
-        let rep = tv.bitmapImageRepForCachingDisplay(in: rect)!
+        // Always 2x: the ink and gap thresholds were tuned on a Retina display, and a 1x host (a CI runner)
+        // would draw a quarter of the pixels with bitmapImageRepForCachingDisplay.
+        let rep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(rect.width * 2), pixelsHigh: Int(rect.height * 2),
+                                   bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false,
+                                   colorSpaceName: .deviceRGB, bytesPerRow: 0, bitsPerPixel: 0)!
+        rep.size = rect.size
         tv.cacheDisplay(in: rect, to: rep)
         if let dir = ProcessInfo.processInfo.environment["CODEBLOCK_PNG_DIR"] {
             let file = "\(dir)/\(name)-\(reading ? "reading" : "writing")-\(dark ? "dark" : "light").png"
diff --git a/Tests/FloStateNativeTests/PointerCursorTests.swift b/Tests/FloStateNativeTests/PointerCursorTests.swift
index b600cd6..5b3caa7 100644
--- a/Tests/FloStateNativeTests/PointerCursorTests.swift
+++ b/Tests/FloStateNativeTests/PointerCursorTests.swift
@@ -89,6 +89,7 @@ final class PointerCursorTests: XCTestCase {
     func testViewsInAWindowInvalidateTheirRectsWhenTheyMoveOrHide() {
         // not hover: only that the hooks run without a window and with one
         let w = NSWindow(contentRect: NSRect(x: -10000, y: -10000, width: 200, height: 100), styleMask: [.titled], backing: .buffered, defer: true)
+        w.isReleasedWhenClosed = false   // close() would release a window ARC also owns: a double release
         let host = NSView(frame: NSRect(x: 0, y: 0, width: 200, height: 100))
         w.contentView = host
         let b = OverflowToggleButton()
diff --git a/Tests/FloStateNativeTests/ShellViewTests.swift b/Tests/FloStateNativeTests/ShellViewTests.swift
index ceca1c0..4b22d5f 100644
--- a/Tests/FloStateNativeTests/ShellViewTests.swift
+++ b/Tests/FloStateNativeTests/ShellViewTests.swift
@@ -54,8 +54,13 @@ final class ShellViewTests: XCTestCase {
         var box = CGRect(x: 0, y: 0, width: 300, height: 400)
         let ctx = CGContext(URL(fileURLWithPath: pdf) as CFURL, mediaBox: &box, nil)!
         ctx.beginPDFPage(nil); ctx.setFillColor(NSColor.systemBlue.cgColor); ctx.fill(CGRect(x: 40, y: 40, width: 220, height: 320)); ctx.endPDFPage(); ctx.beginPDFPage(nil); ctx.endPDFPage(); ctx.closePDF()
-        let img = NSImage(size: NSSize(width: 64, height: 32)); img.lockFocus(); NSColor.red.setFill(); NSRect(x: 0, y: 0, width: 64, height: 32).fill(); img.unlockFocus()
-        try NSBitmapImageRep(data: img.tiffRepresentation!)!.representation(using: .png, properties: [:])!.write(to: URL(fileURLWithPath: png))
+        let rep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: 128, pixelsHigh: 64, bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true,
+                                   isPlanar: false, colorSpaceName: .deviceRGB, bytesPerRow: 0, bitsPerPixel: 0)!
+        NSGraphicsContext.saveGraphicsState()
+        NSGraphicsContext.current = NSGraphicsContext(bitmapImageRep: rep)
+        NSColor.red.setFill(); NSRect(x: 0, y: 0, width: 128, height: 64).fill()
+        NSGraphicsContext.restoreGraphicsState()
+        try rep.representation(using: .png, properties: [:])!.write(to: URL(fileURLWithPath: png))
         let before = try Data(contentsOf: URL(fileURLWithPath: png))
         for (path, kind) in [(pdf, WorkspaceFS.ViewerKind.pdf), (png, .image)] {
             try await f.model.editor.openFileInTabOrFocus(path)