diff --git a/server/src/__tests__/issues-service.test.ts b/server/src/__tests__/issues-service.test.ts
index 077332c61c2..4d6cf1f88f1 100644
--- a/server/src/__tests__/issues-service.test.ts
+++ b/server/src/__tests__/issues-service.test.ts
@@ -3112,4 +3112,96 @@ describeEmbeddedPostgres("issueService.clearExecutionRunIfTerminal", () => {
       .then((rows) => rows[0]);
     expect(row).toEqual({ executionRunId: null, executionLockedAt: null });
   });
+
+  it("does not let stale release clobber a successor checkout lock", async () => {
+    const companyId = randomUUID();
+    const agentId = randomUUID();
+    const issueId = randomUUID();
+    const failedRunId = randomUUID();
+    const releasingRunId = randomUUID();
+    const successorRunId = randomUUID();
+
+    await db.insert(companies).values({
+      id: companyId,
+      name: "Paperclip",
+      issuePrefix: `T${companyId.replace(/-/g, "").slice(0, 6).toUpperCase()}`,
+      requireBoardApprovalForNewAgents: false,
+    });
+    await db.insert(agents).values({
+      id: agentId,
+      companyId,
+      name: "CodexCoder",
+      role: "engineer",
+      status: "active",
+      adapterType: "codex_local",
+      adapterConfig: {},
+      runtimeConfig: {},
+      permissions: {},
+    });
+    await db.insert(heartbeatRuns).values([
+      {
+        id: failedRunId,
+        companyId,
+        agentId,
+        status: "failed",
+        invocationSource: "manual",
+        finishedAt: new Date("2026-06-10T10:05:00.000Z"),
+      },
+      {
+        id: releasingRunId,
+        companyId,
+        agentId,
+        status: "running",
+        invocationSource: "manual",
+        startedAt: new Date("2026-06-10T10:06:00.000Z"),
+      },
+      {
+        id: successorRunId,
+        companyId,
+        agentId,
+        status: "running",
+        invocationSource: "manual",
+        startedAt: new Date("2026-06-10T10:07:00.000Z"),
+      },
+    ]);
+    await db.insert(issues).values({
+      id: issueId,
+      companyId,
+      title: "Race stale release",
+      status: "in_progress",
+      priority: "high",
+      assigneeAgentId: agentId,
+      checkoutRunId: failedRunId,
+      executionRunId: failedRunId,
+      executionAgentNameKey: "codexcoder",
+      executionLockedAt: new Date("2026-06-10T10:00:00.000Z"),
+    });
+
+    const [releaseResult, checkoutResult] = await Promise.allSettled([
+      svc.release(issueId, agentId, releasingRunId),
+      svc.checkout(issueId, agentId, ["todo", "in_progress"], successorRunId),
+    ]);
+
+    expect(checkoutResult.status).toBe("fulfilled");
+    if (releaseResult.status === "rejected") {
+      expect(releaseResult.reason).toMatchObject({ status: 409 });
+    }
+
+    const row = await db
+      .select({
+        status: issues.status,
+        assigneeAgentId: issues.assigneeAgentId,
+        checkoutRunId: issues.checkoutRunId,
+        executionRunId: issues.executionRunId,
+      })
+      .from(issues)
+      .where(eq(issues.id, issueId))
+      .then((rows) => rows[0]);
+    expect(row).toMatchObject({
+      status: "in_progress",
+      assigneeAgentId: agentId,
+      checkoutRunId: successorRunId,
+      executionRunId: successorRunId,
+    });
+  });
 });
diff --git a/server/src/services/issues.ts b/server/src/services/issues.ts
index e0839371d59..8e8ca0d8546 100644
--- a/server/src/services/issues.ts
+++ b/server/src/services/issues.ts
@@ -3256,8 +3256,8 @@ export function issueService(db: Db) {
     );
   }
 
-  async function isTerminalOrMissingHeartbeatRun(runId: string) {
-    const run = await db
+  async function isTerminalOrMissingHeartbeatRun(runId: string, dbOrTx: DbReader = db) {
+    const run = await dbOrTx
       .select({ status: heartbeatRuns.status })
       .from(heartbeatRuns)
       .where(eq(heartbeatRuns.id, runId))
@@ -4867,55 +4867,57 @@ export function issueService(db: Db) {
       });
     },
 
-    release: async (id: string, actorAgentId?: string, actorRunId?: string | null) => {
-      await clearExecutionRunIfTerminal(id);
-      await clearCheckoutRunIfTerminal(id);
-      const existing = await db
-        .select()
-        .from(issues)
-        .where(eq(issues.id, id))
-        .then((rows) => rows[0] ?? null);
+    release: async (id: string, actorAgentId?: string, actorRunId?: string | null) =>
+      db.transaction(async (tx) => {
+        await tx.execute(
+          sql`select ${issues.id} from ${issues} where ${issues.id} = ${id} for update`,
+        );
+        const existing = await tx
+          .select()
+          .from(issues)
+          .where(eq(issues.id, id))
+          .then((rows) => rows[0] ?? null);
 
-      if (!existing) return null;
-      if (actorAgentId && existing.assigneeAgentId && existing.assigneeAgentId !== actorAgentId) {
-        throw conflict("Only assignee can release issue");
-      }
-      if (
-        actorAgentId &&
-        existing.status === "in_progress" &&
-        existing.assigneeAgentId === actorAgentId &&
-        existing.checkoutRunId &&
-        !sameRunLock(existing.checkoutRunId, actorRunId ?? null)
-      ) {
-        const stale = await isTerminalOrMissingHeartbeatRun(existing.checkoutRunId);
-        if (!stale) {
-          throw conflict("Only checkout run can release issue", {
-            issueId: existing.id,
-            assigneeAgentId: existing.assigneeAgentId,
-            checkoutRunId: existing.checkoutRunId,
-            actorRunId: actorRunId ?? null,
-          });
+        if (!existing) return null;
+        if (actorAgentId && existing.assigneeAgentId && existing.assigneeAgentId !== actorAgentId) {
+          throw conflict("Only assignee can release issue");
+        }
+        if (
+          actorAgentId &&
+          existing.status === "in_progress" &&
+          existing.assigneeAgentId === actorAgentId &&
+          existing.checkoutRunId &&
+          !sameRunLock(existing.checkoutRunId, actorRunId ?? null)
+        ) {
+          const stale = await isTerminalOrMissingHeartbeatRun(existing.checkoutRunId, tx);
+          if (!stale) {
+            throw conflict("Only checkout run can release issue", {
+              issueId: existing.id,
+              assigneeAgentId: existing.assigneeAgentId,
+              checkoutRunId: existing.checkoutRunId,
+              actorRunId: actorRunId ?? null,
+            });
+          }
         }
-      }
 
-      const updated = await db
-        .update(issues)
-        .set({
-          status: "todo",
-          assigneeAgentId: null,
-          checkoutRunId: null,
-          executionRunId: null,
-          executionAgentNameKey: null,
-          executionLockedAt: null,
-          updatedAt: new Date(),
-        })
-        .where(eq(issues.id, id))
-        .returning()
-        .then((rows) => rows[0] ?? null);
-      if (!updated) return null;
-      const [enriched] = await withIssueLabels(db, [updated]);
-      return enriched;
-    },
+        const updated = await tx
+          .update(issues)
+          .set({
+            status: "todo",
+            assigneeAgentId: null,
+            checkoutRunId: null,
+            executionRunId: null,
+            executionAgentNameKey: null,
+            executionLockedAt: null,
+            updatedAt: new Date(),
+          })
+          .where(eq(issues.id, id))
+          .returning()
+          .then((rows) => rows[0] ?? null);
+        if (!updated) return null;
+        const [enriched] = await withIssueLabels(tx, [updated]);
+        return enriched;
+      }),
 
     adminForceRelease: async (id: string, options: { clearAssignee?: boolean } = {}) =>
       db.transaction(async (tx) => {