From 45bccb700d9250efead64cf68dc10399ff35ed74 Mon Sep 17 00:00:00 2001
From: Nicky Leach <nicky@paperclip.ing>
Date: Sat, 20 Jun 2026 02:13:58 +0000
Subject: [PATCH] Serialize gate confirmation mirror writes

---
 server/src/__tests__/issues-service.test.ts |  8 +++++++-
 server/src/services/issues.ts               | 12 +++++++-----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/server/src/__tests__/issues-service.test.ts b/server/src/__tests__/issues-service.test.ts
index 1d6c13a6593..684576f61ef 100644
--- a/server/src/__tests__/issues-service.test.ts
+++ b/server/src/__tests__/issues-service.test.ts
@@ -2957,7 +2957,13 @@ describeEmbeddedPostgres("issueService.create workspace inheritance", () => {
       body: `A user pasted the mirror marker: <!-- gate-confirmation-mirror:${child.id} -->`,
     });
 
-    const mirrored = await svc.mirrorGateConfirmationToParent(child.id);
+    const mirrorResults = await Promise.all([
+      svc.mirrorGateConfirmationToParent(child.id),
+      svc.mirrorGateConfirmationToParent(child.id),
+    ]);
+    expect(mirrorResults.filter(Boolean)).toHaveLength(1);
+    expect(mirrorResults.filter((result) => result === null)).toHaveLength(1);
+    const mirrored = mirrorResults.find(Boolean);
     expect(mirrored).toMatchObject({
       issueId: parentIssueId,
       authorType: "system",
diff --git a/server/src/services/issues.ts b/server/src/services/issues.ts
index d4e6d260de7..b53aefca7c0 100644
--- a/server/src/services/issues.ts
+++ b/server/src/services/issues.ts
@@ -4645,8 +4645,8 @@ export function issueService(db: Db) {
       };
     },
 
-    mirrorGateConfirmationToParent: async (childIssueId: string) => {
-      const child = await db
+    mirrorGateConfirmationToParent: async (childIssueId: string) => db.transaction(async (tx) => {
+      const child = await tx
         .select({
           id: issues.id,
           companyId: issues.companyId,
@@ -4658,6 +4658,7 @@ export function issueService(db: Db) {
         })
         .from(issues)
         .where(eq(issues.id, childIssueId))
+        .for("update")
         .then((rows) => rows[0] ?? null);
       if (!child || child.status !== "done" || !child.parentId) return null;
 
@@ -4665,7 +4666,7 @@ export function issueService(db: Db) {
       if (!mirror || mirror.parentIssueId !== child.parentId) return null;
 
       const marker = buildGateConfirmationMirrorMarker(child.id);
-      const existingMirror = await db
+      const existingMirror = await tx
         .select({ id: issueComments.id })
         .from(issueComments)
         .where(and(
@@ -4678,7 +4679,7 @@ export function issueService(db: Db) {
         .then((rows) => rows[0] ?? null);
       if (existingMirror) return null;
 
-      const latestChildComment = await db
+      const latestChildComment = await tx
         .select({ body: issueComments.body })
         .from(issueComments)
         .where(and(
@@ -4700,8 +4701,9 @@ export function issueService(db: Db) {
         }),
         {},
         { authorType: "system" },
+        tx,
       );
-    },
+    }),
 
     createChild: async (
       parentIssueId: string,