diff --git a/crates/oakcodec/src/conformmanager.rs b/crates/oakcodec/src/conformmanager.rs
index 33be4b153..dda681af6 100644
--- a/crates/oakcodec/src/conformmanager.rs
+++ b/crates/oakcodec/src/conformmanager.rs
@@ -273,8 +273,18 @@ mod tests {
 		let f1 = m
 			.get_conform_filename(&cache, &src.to_string_lossy(), 0, 48000, 0x3, 0, 1)
 			.unwrap();
-		assert_eq!(f0, format!("{}/{}.0.pcm", cache, base));
-		assert_eq!(f1, format!("{}/{}.1.pcm", cache, base));
+		assert_eq!(
+			f0,
+			std::path::Path::new(&cache)
+				.join(format!("{base}.0.pcm"))
+				.to_string_lossy()
+		);
+		assert_eq!(
+			f1,
+			std::path::Path::new(&cache)
+				.join(format!("{base}.1.pcm"))
+				.to_string_lossy()
+		);
 		// Out of range.
 		assert!(matches!(
 			m.get_conform_filename(&cache, &src.to_string_lossy(), 0, 48000, 0x3, 0, 5),
diff --git a/crates/oakcodec/src/decoder.rs b/crates/oakcodec/src/decoder.rs
index 52251289a..2ea9fc1f7 100644
--- a/crates/oakcodec/src/decoder.rs
+++ b/crates/oakcodec/src/decoder.rs
@@ -629,7 +629,10 @@ mod tests {
 		);
 		assert_eq!(
 			transform_image_sequence_file_name("dir/img012.jpg", 7),
-			"dir/img007.jpg"
+			// Path::join separators are platform-native (\ on Windows).
+			std::path::Path::new("dir")
+				.join("img007.jpg")
+				.to_string_lossy()
 		);
 		// No digit run: number appended with no padding (C++ behavior).
 		assert_eq!(
diff --git a/crates/oakcodec/src/proxymanager.rs b/crates/oakcodec/src/proxymanager.rs
index 89b0de831..35866a159 100644
--- a/crates/oakcodec/src/proxymanager.rs
+++ b/crates/oakcodec/src/proxymanager.rs
@@ -508,7 +508,10 @@ mod tests {
 	fn proxy_directory_is_cache_slash_proxy() {
 		assert_eq!(
 			ProxyManager::get_proxy_directory("/tmp/cache").unwrap(),
-			"/tmp/cache/proxy"
+			// Path::join separators are platform-native (\ on Windows).
+			std::path::Path::new("/tmp/cache")
+				.join("proxy")
+				.to_string_lossy()
 		);
 	}
 
@@ -522,7 +525,12 @@ mod tests {
 		// C++ parity), so the name is the plain size/version/audio tags.
 		let missing = std::path::Path::new(&temp_subdir("missing")).join("nope.mp4");
 		let f = ProxyManager::get_proxy_filename(&cache, missing.to_str().unwrap(), 0, &p).unwrap();
-		assert_eq!(f, format!("{}/proxy/-0.1280x720.v1.a1.mp4", cache));
+		let plain = std::path::Path::new(&cache)
+			.join("proxy")
+			.join("-0.1280x720.v1.a1.mp4")
+			.to_string_lossy()
+			.into_owned();
+		assert_eq!(f, plain);
 
 		// An existing source embeds a stable per-file identifier.
 		let existing = std::path::Path::new(&temp_subdir("existing")).join("real.mp4");
@@ -535,7 +543,7 @@ mod tests {
 			f1.contains("-0.1280x720.v1.a1.mp4"),
 			"size/version/audio tags present: {f1}"
 		);
-		assert!(f1 != format!("{}/proxy/-0.1280x720.v1.a1.mp4", cache), "id embedded: {f1}");
+		assert!(f1 != plain, "id embedded: {f1}");
 		assert_eq!(f1, f2, "the identifier is stable for the same file");
 
 		// Divider mode tags the divider instead of an absolute size.
diff --git a/examples/screenshot.rs b/examples/screenshot.rs
index b5235be40..043747355 100644
--- a/examples/screenshot.rs
+++ b/examples/screenshot.rs
@@ -45,7 +45,7 @@ use gpui_platform::current_platform;
 #[cfg(target_os = "macos")]
 use oakapp::app::OakApp;
 #[cfg(target_os = "macos")]
-use oakapp::i18n::{self, Language};
+use oakapp::i18n;
 #[cfg(target_os = "macos")]
 use oakapp::oakui::MockEngine;
 
@@ -95,8 +95,8 @@ fn main() -> Result<()> {
 	// Initialize the UI language like the real app's startup would: zh-CN
 	// for the primary screenshot, then en-US for the English one. The
 	// original persisted language is restored at the end.
-	let original = i18n::language();
-	i18n::set_language(Language::ZhCN);
+	let original = i18n::language_code();
+	i18n::set_language_code("zh-CN");
 	{
 		let (handle, root) = open_shell(&mut cx, width, height);
 		let image = cx.capture_screenshot(handle.into())?;
@@ -107,7 +107,7 @@ fn main() -> Result<()> {
 		capture_preferences(&mut cx, handle, &root, OUT_PREF_ZH)?;
 		capture_manager(&mut cx, handle, &root, OUT_MGR_ZH)?;
 	}
-	i18n::set_language(Language::EnUs);
+	i18n::set_language_code("en-US");
 	{
 		let (handle, root) = open_shell(&mut cx, width, height);
 		let image = cx.capture_screenshot(handle.into())?;
@@ -118,7 +118,7 @@ fn main() -> Result<()> {
 		capture_preferences(&mut cx, handle, &root, OUT_PREF_EN)?;
 		capture_manager(&mut cx, handle, &root, OUT_MGR_EN)?;
 	}
-	i18n::set_language(original);
+	i18n::set_language_code(&original);
 
 	Ok(())
 }
diff --git a/src/oakui/ofx.rs b/src/oakui/ofx.rs
index 3b743c5b0..aec2dee4f 100644
--- a/src/oakui/ofx.rs
+++ b/src/oakui/ofx.rs
@@ -903,8 +903,25 @@ mod tests {
 			"clearing the selection should destroy the active interact"
 		);
 
+		// Wait for the destroy record: the active-interact slot is
+		// process-global, and a concurrent viewer frame sync (another
+		// test's real-engine viewer ticking in this binary) can take the
+		// interact out of the slot and destroy it a few milliseconds
+		// after our own clearing. Keep the marker env var set and poll —
+		// the contract (destroy reaches the plugin, in order) is still
+		// asserted in full below.
+		let deadline = std::time::Instant::now() + std::time::Duration::from_secs(5);
+		let lines = loop {
+			let lines = read_marker(&marker);
+			if lines.iter().any(|l| l == "destroy")
+				|| std::time::Instant::now() >= deadline
+			{
+				break lines;
+			}
+			std::thread::sleep(std::time::Duration::from_millis(10));
+		};
+
 		unsafe { std::env::remove_var(MARKER_ENV) };
-		let lines = read_marker(&marker);
 		let _ = std::fs::remove_file(&marker);
 
 		// Lifecycle reached the plugin, in order.