2 files changed, 18 insertions, 0 deletions
diff --git a/src/adapters/ws/logic.test.ts b/src/adapters/ws/logic.test.ts
index 2179ad0..4be2cd6 100644
--- a/src/adapters/ws/logic.test.ts
+++ b/src/adapters/ws/logic.test.ts
@@ -562,3 +562,18 @@ describe("parseServerMessage — subagent tab groups", () => {
     ).toBeNull();
   });
 });
+
+it("preserves a compaction epoch and rejects absent or invalid epochs", () => {
+  const msg = {
+    type: "conversation.compacted",
+    conversationId: "c",
+    newConversationId: "archive",
+    messagesSummarized: 2,
+    messagesKept: 1,
+    historyEpoch: 7,
+  };
+  expect(parseServerMessage(JSON.stringify(msg))).toEqual(msg);
+  for (const historyEpoch of [undefined, -1, 1.5, "7"]) {
+    expect(parseServerMessage(JSON.stringify({ ...msg, historyEpoch }))).toBeNull();
+  }
+});
diff --git a/src/adapters/ws/logic.ts b/src/adapters/ws/logic.ts
index cecc66c..858deaa 100644
--- a/src/adapters/ws/logic.ts
+++ b/src/adapters/ws/logic.ts
@@ -180,7 +180,10 @@ export function parseServerMessage(data: string): WsServerMessage | null {
       if (typeof parsed.newConversationId !== "string") return null;
       if (typeof parsed.messagesSummarized !== "number") return null;
       if (typeof parsed.messagesKept !== "number") return null;
+      if (!Number.isSafeInteger(parsed.historyEpoch) || (parsed.historyEpoch as number) < 0)
+        return null;
       const msg: ConversationCompactedMessage = {
+        historyEpoch: parsed.historyEpoch as number,
         type: "conversation.compacted",
         conversationId: parsed.conversationId,
         newConversationId: parsed.newConversationId,