diff --git a/packages/tui/test/editor.test.ts b/packages/tui/test/editor.test.ts
index 1af316879..f884fb314 100644
--- a/packages/tui/test/editor.test.ts
+++ b/packages/tui/test/editor.test.ts
@@ -1025,7 +1025,7 @@ describe("Editor component", () => {
 				await terminal.waitForRender();
 				for (const char of "ast") editor.handleInput(char);
 				tui.requestRender();
-				await terminal.waitForRender();
+				await terminal.waitForRender(() => terminal.getViewport()[1]?.includes("ast") === true);
 
 				const beforePreedit = terminal.getViewport().map(row => row.trimEnd());
 				expect(beforePreedit.slice(0, 3)).toEqual(["+------------------+", "|  ast", "+------------------+"]);
diff --git a/packages/tui/test/virtual-terminal.ts b/packages/tui/test/virtual-terminal.ts
index 3821ba0c8..8a7908bd6 100644
--- a/packages/tui/test/virtual-terminal.ts
+++ b/packages/tui/test/virtual-terminal.ts
@@ -280,12 +280,21 @@ export class VirtualTerminal implements Terminal {
 
 	// --- Test-only helpers ---------------------------------------------------
 
-	/** Wait for TUI's throttled render pipeline to settle (matches the ~33ms frame budget). */
-	async waitForRender(): Promise<void> {
+	/**
+	 * Wait for TUI's throttled render pipeline to settle (matches the ~33ms
+	 * frame budget). Fixed sleeps race starved CI timers, so callers asserting
+	 * on a specific frame pass `until`; polling continues (10ms slices, ~2s
+	 * cap) until the predicate observes the expected viewport.
+	 */
+	async waitForRender(until?: () => boolean): Promise<void> {
 		const nextTick = Promise.withResolvers<void>();
 		process.nextTick(nextTick.resolve);
 		await nextTick.promise;
 		await Bun.sleep(40);
+		if (until) {
+			const deadline = Date.now() + 2_000;
+			while (!until() && Date.now() < deadline) await Bun.sleep(10);
+		}
 		await this.flush();
 	}