diff --git a/src/agents/accepted-session-spawn.ts b/src/agents/accepted-session-spawn.ts
index f7366345fc3..9dc64d49f4e 100644
--- a/src/agents/accepted-session-spawn.ts
+++ b/src/agents/accepted-session-spawn.ts
@@ -24,12 +24,14 @@ export function normalizeAcceptedSessionSpawnResult(result: unknown): AcceptedSe
   return { runId, childSessionKey };
 }
 
-export function hasAcceptedSessionSpawn(
-  acceptedSessionSpawns?: readonly AcceptedSessionSpawn[],
-): boolean {
+export function hasAcceptedSessionSpawn(acceptedSessionSpawns?: readonly unknown[]): boolean {
   return (acceptedSessionSpawns ?? []).some((spawn) => {
+    const record = asRecord(spawn);
+    if (!record) {
+      return false;
+    }
     return Boolean(
-      normalizeOptionalString(spawn.runId) && normalizeOptionalString(spawn.childSessionKey),
+      normalizeOptionalString(record.runId) && normalizeOptionalString(record.childSessionKey),
     );
   });
 }
diff --git a/src/agents/pi-embedded-runner/run.incomplete-turn.test.ts b/src/agents/pi-embedded-runner/run.incomplete-turn.test.ts
index 89e0fea8b99..c1dfea90bc0 100644
--- a/src/agents/pi-embedded-runner/run.incomplete-turn.test.ts
+++ b/src/agents/pi-embedded-runner/run.incomplete-turn.test.ts
@@ -1883,6 +1883,20 @@ describe("runEmbeddedPiAgent incomplete-turn safety", () => {
     expect(hasOutboundDeliveryEvidence({ acceptedSessionSpawns })).toBe(true);
   });
 
+  it("ignores malformed accepted sessions_spawn delivery evidence", () => {
+    expect(
+      hasOutboundDeliveryEvidence({
+        acceptedSessionSpawns: [
+          null,
+          {
+            runId: "run-child",
+            childSessionKey: " ",
+          },
+        ],
+      }),
+    ).toBe(false);
+  });
+
   it("leaves committed delivery plus tool errors to the tool-error payload path", () => {
     const incompleteTurnText = resolveIncompleteTurnPayloadText({
       payloadCount: 0,