diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 06fdcec1..9b9093bb 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -32,7 +32,7 @@
 				"@tailwindcss/vite": "^4.1.17",
 				"@types/diff": "^7.0.2",
 				"@types/node": "^24",
-				"@vitest/browser-playwright": "^4.0.10",
+				"@vitest/browser-playwright": "4.1.6",
 				"@vitest/coverage-istanbul": "^4.1.0",
 				"@vitest/coverage-v8": "^4.1.0",
 				"eslint": "^9.39.1",
diff --git a/frontend/package.json b/frontend/package.json
index 0f135964..9b2aec05 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -3,6 +3,7 @@
 	"private": true,
 	"version": "0.0.1",
 	"type": "module",
+	"//@vitest/browser-playwright": "Exact-pinned (no caret) to 4.1.6 so patches/@vitest+browser-playwright+4.1.6.patch (backport of vitest PR #10267, the duplicate-mock-id birpc race) keeps applying. TODO: remove this pin and the patch once @vitest/browser-playwright ships a release containing PR #10267. See docs/adr/012-browser-test-mocking-strategy.md.",
 	"scripts": {
 		"dev": "vite dev",
 		"build": "vite build",
@@ -47,7 +48,7 @@
 		"@tailwindcss/vite": "^4.1.17",
 		"@types/diff": "^7.0.2",
 		"@types/node": "^24",
-		"@vitest/browser-playwright": "^4.0.10",
+		"@vitest/browser-playwright": "4.1.6",
 		"@vitest/coverage-istanbul": "^4.1.0",
 		"@vitest/coverage-v8": "^4.1.0",
 		"eslint": "^9.39.1",