diff --git a/src/context-engine.ts b/src/context-engine.ts
index 98bc9f2..e5a2b20 100644
--- a/src/context-engine.ts
+++ b/src/context-engine.ts
@@ -711,7 +711,6 @@ export function buildContextEngineFactory(
           sessionKey: args.sessionKey,
           userId: args.userId,
           messages,
-          prePromptMessageCount: args.prePromptMessageCount,
           isHeartbeat: args.isHeartbeat,
         });
         await performAfterTurnPredictiveCompaction({
@@ -723,8 +722,11 @@ export function buildContextEngineFactory(
       }
       const rpc = await runtime.getRpc();
       const result = await rpc.call("after_turn_kernel", {
-        ...args,
+        sessionId: args.sessionId,
+        sessionKey: args.sessionKey,
+        userId: args.userId,
         messages,
+        isHeartbeat: args.isHeartbeat,
       });
       await performAfterTurnPredictiveCompaction({
         sessionId: args.sessionId,
diff --git a/test/integration/host-flow.test.ts b/test/integration/host-flow.test.ts
index c13df1f..c9a3c93 100644
--- a/test/integration/host-flow.test.ts
+++ b/test/integration/host-flow.test.ts
@@ -445,7 +445,7 @@ test("compact omits invalid currentTokenCount values from the wire request", asy
   assert.equal("currentTokenCount" in params, false);
 });
 
-test("afterTurn forwards message arrays and pre-prompt counts correctly", async () => {
+test("afterTurn forwards only daemon-relevant fields, strips prePromptMessageCount", async () => {
   const rpc = new StaticContractRpc();
   const recallCache = createRecallCache<SearchResult>();
   const cfg: PluginConfig = { rpcTimeoutMs: 1000 };
@@ -469,7 +469,7 @@ test("afterTurn forwards message arrays and pre-prompt counts correctly", async
   assert.ok(params, "Expected after_turn_kernel to be called");
   assert.equal(params.sessionId, "test-session");
   assert.equal(params.userId, "test-user");
-  assert.equal(params.prePromptMessageCount, 2);
+  assert.equal("prePromptMessageCount" in params, false, "prePromptMessageCount must not leak to daemon — daemon defaults to 0 and uses content-hash dedup");
   assert.equal(params.isHeartbeat, false);
   assert.deepEqual(params.messages, mockMessages);
 });