diff --git a/packages/plugins/plugin-missions/src/mission-service.ts b/packages/plugins/plugin-missions/src/mission-service.ts
index a7140730b8e..3a2b976dfc9 100644
--- a/packages/plugins/plugin-missions/src/mission-service.ts
+++ b/packages/plugins/plugin-missions/src/mission-service.ts
@@ -331,6 +331,12 @@ function normalizeId(value: string) {
   return value.trim().toUpperCase();
 }
 
+function toIsoDateString(value: Date | string | null | undefined): string {
+  if (value instanceof Date) return value.toISOString();
+  if (typeof value === "string") return value;
+  return new Date(0).toISOString();
+}
+
 function rootMissionOrigin(pluginId: string) {
   return `plugin:${pluginId}`;
 }
@@ -1585,7 +1591,7 @@ export async function listMissionSummaries(ctx: PluginContext, companyId: string
       },
       costCents: summary.costSummary.costCents,
       latestRunStatus: summary.runSummary.latestRunStatus,
-      updatedAt: root.updatedAt.toISOString(),
+      updatedAt: toIsoDateString(root.updatedAt),
     }))
     .sort((a, b) => b.updatedAt.localeCompare(a.updatedAt));
 }
diff --git a/packages/plugins/plugin-missions/src/ui/index.tsx b/packages/plugins/plugin-missions/src/ui/index.tsx
index efb4b682716..71571bb3e0f 100644
--- a/packages/plugins/plugin-missions/src/ui/index.tsx
+++ b/packages/plugins/plugin-missions/src/ui/index.tsx
@@ -204,6 +204,10 @@ function formatDate(value: string | null) {
   });
 }
 
+function findingRenderKey(finding: MissionSummary["validationSummary"]["findings"][number]) {
+  return `${finding.sourceReportKey}:${finding.id}`;
+}
+
 function Section({
   title,
   action,
@@ -408,7 +412,7 @@ function SummarySections({
         {summary.validationSummary.findings.length > 0 ? (
           <div style={listGridStyle}>
             {summary.validationSummary.findings.map((finding) => (
-              <div key={finding.id} style={metricStyle}>
+              <div key={findingRenderKey(finding)} style={metricStyle}>
                 <div style={rowStyle}>
                   <strong>{finding.title}</strong>
                   <span style={mutedTextStyle}>
diff --git a/packages/plugins/plugin-missions/tests/plugin.spec.ts b/packages/plugins/plugin-missions/tests/plugin.spec.ts
index 9bca1d1fc45..9e0643de3ae 100644
--- a/packages/plugins/plugin-missions/tests/plugin.spec.ts
+++ b/packages/plugins/plugin-missions/tests/plugin.spec.ts
@@ -220,4 +220,35 @@ describe("missions plugin worker", () => {
       expect.objectContaining({ id: workerAgentId, name: "Worker One" }),
     ]);
   });
+
+  it("lists persisted mission roots when host issue timestamps are serialized strings", async () => {
+    const companyId = randomUUID();
+    const rootIssueId = randomUUID();
+    const updatedAt = "2026-04-20T12:00:00.000Z";
+    const harness = createTestHarness({ manifest });
+
+    harness.seed({
+      issues: [
+        issue({
+          id: rootIssueId,
+          companyId,
+          title: "Persisted mission root",
+          identifier: "PAP-1691",
+          originKind: "plugin:paperclip.missions",
+          updatedAt: updatedAt as unknown as Date,
+        }),
+      ],
+    });
+
+    await plugin.definition.setup(harness.ctx);
+
+    const list = await harness.getData<Array<Record<string, unknown>>>("mission-list", { companyId });
+    expect(list).toEqual([
+      expect.objectContaining({
+        missionIssueId: rootIssueId,
+        missionTitle: "Persisted mission root",
+        updatedAt,
+      }),
+    ]);
+  });
 });