From 50eb4117c61d336e23fff3980cd8538afa8b2ee8 Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Sun, 6 Sep 2026 19:51:25 -0700
Subject: [PATCH] test: publish restored snapshot before draining its held FIFO

---
 .../ssh-cold-hydration-gap-tab-seeding.spec.ts   | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/tests/e2e/ssh-cold-hydration-gap-tab-seeding.spec.ts b/tests/e2e/ssh-cold-hydration-gap-tab-seeding.spec.ts
index cdcdf38fa5a..93b16df0a11 100644
--- a/tests/e2e/ssh-cold-hydration-gap-tab-seeding.spec.ts
+++ b/tests/e2e/ssh-cold-hydration-gap-tab-seeding.spec.ts
@@ -128,8 +128,16 @@ function unblockRemoteWorkspaceGet(
   snapshotPath: string,
   saved: string
 ): void {
-  // Detached: a FIFO write blocks until the reader drains it, which must not stall the test.
-  spawnSync('docker', [
+  const replacementPath = `${snapshotPath}.release`
+  const releaseScript = [
+    `printf '%s' ${shellQuote(saved)} > ${shellQuote(replacementPath)}`,
+    `exec 3> ${shellQuote(snapshotPath)}`,
+    // Publish the complete file before the held reader can issue another snapshot read.
+    `mv -f ${shellQuote(replacementPath)} ${shellQuote(snapshotPath)}`,
+    `printf '%s' ${shellQuote(saved)} >&3`,
+    'exec 3>&-'
+  ].join(' && ')
+  const release = spawnSync('docker', [
     'exec',
     '-d',
     target.containerName,
@@ -137,8 +145,10 @@ function unblockRemoteWorkspaceGet(
     '--noprofile',
     '--norc',
     '-c',
-    `printf '%s' ${shellQuote(saved)} > ${snapshotPath} && rm -f ${snapshotPath} && printf '%s' ${shellQuote(saved)} > ${snapshotPath}`
+    releaseScript
   ])
+  expect(release.error, 'failed to launch the snapshot release writer').toBeUndefined()
+  expect(release.status, release.stderr?.toString()).toBe(0)
 }
 
 async function connectAndSeedTabs(