From 378265c3cd63c384c9bde1532be5e9e21b7b0b34 Mon Sep 17 00:00:00 2001
From: Constantin Jais <74049135+constantin-jais@users.noreply.github.com>
Date: Fri, 9 Oct 2026 05:16:10 +0200
Subject: [PATCH] test(e2e): disable Firefox COOP process swap in starter
 Firefox projects

Playwright's Firefox driver (Juggler) can lose a protocol message when a
navigation response carries Cross-Origin-Opener-Policy: same-origin and
Firefox replaces the browsing context, so page.goto or the following
evaluate hangs intermittently (microsoft/playwright#42731, fixed in
Firefox r1551 shipped with Playwright 1.64.0, not yet installable under
the 3-day minimumReleaseAge).

Temporary workaround in the starter and bun-app Firefox projects:
launch Firefox with browser.tabs.remote.useCrossOriginOpenerPolicy=false.
The COOP header served by web-platform is unchanged; header assertions
still run. Remove once @playwright/test >= 1.64.0.

Local evidence (macOS arm64, --repeat-each=30, Firefox project):
starter 1/150 failed before (page.goto timeout), 0/150 after;
bun-app 1/90 failed before (page.goto timeout), 0/90 after.

Claude-Session: https://claude.ai/code/session_01YGo2fqxeSVRfXjQErze6hP
Signed-off-by: Constantin Jais <74049135+constantin-jais@users.noreply.github.com>
---
 packages/starter/bun-app/playwright.config.ts | 8 +++++++-
 packages/starter/starter/playwright.config.ts | 8 +++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/packages/starter/bun-app/playwright.config.ts b/packages/starter/bun-app/playwright.config.ts
index 5f77db5..ddb54df 100644
--- a/packages/starter/bun-app/playwright.config.ts
+++ b/packages/starter/bun-app/playwright.config.ts
@@ -12,7 +12,13 @@ export default defineConfig({
     {
       name: "firefox",
       testMatch: /(reference|hydration-marker)\.e2e\.ts/,
-      use: { ...devices["Desktop Firefox"] },
+      use: {
+        ...devices["Desktop Firefox"],
+        // TODO(playwright-1.64): remove once @playwright/test >= 1.64.0 (microsoft/playwright#42731) — Juggler loses a message on COOP-triggered context replacement.
+        launchOptions: {
+          firefoxUserPrefs: { "browser.tabs.remote.useCrossOriginOpenerPolicy": false },
+        },
+      },
     },
     {
       name: "webkit",
diff --git a/packages/starter/starter/playwright.config.ts b/packages/starter/starter/playwright.config.ts
index b521e92..04a4eae 100644
--- a/packages/starter/starter/playwright.config.ts
+++ b/packages/starter/starter/playwright.config.ts
@@ -22,7 +22,13 @@ export default defineConfig({
     {
       name: "firefox",
       testMatch: /journal\.e2e\.ts/,
-      use: { ...devices["Desktop Firefox"] },
+      use: {
+        ...devices["Desktop Firefox"],
+        // TODO(playwright-1.64): remove once @playwright/test >= 1.64.0 (microsoft/playwright#42731) — Juggler loses a message on COOP-triggered context replacement.
+        launchOptions: {
+          firefoxUserPrefs: { "browser.tabs.remote.useCrossOriginOpenerPolicy": false },
+        },
+      },
     },
     {
       name: "webkit",