diff --git a/src/commands/agent/delivery.ts b/src/commands/agent/delivery.ts
index caecb2a6283..fdb0319dfbd 100644
--- a/src/commands/agent/delivery.ts
+++ b/src/commands/agent/delivery.ts
@@ -230,6 +230,7 @@ export async function deliverAgentCommandResult(params: {
         onError: (err) => logDeliveryError(err),
         onPayload: logPayload,
         deps: createOutboundSendDeps(deps),
+        sessionKey: opts.sessionKey,
       });
     }
   }
diff --git a/src/cron/isolated-agent/delivery-dispatch.ts b/src/cron/isolated-agent/delivery-dispatch.ts
index 1feae211df8..c6040a61774 100644
--- a/src/cron/isolated-agent/delivery-dispatch.ts
+++ b/src/cron/isolated-agent/delivery-dispatch.ts
@@ -182,6 +182,7 @@ export async function dispatchCronDelivery(
         bestEffort: params.deliveryBestEffort,
         deps: createOutboundSendDeps(params.deps),
         abortSignal: params.abortSignal,
+        sessionKey: params.agentSessionKey,
       });
       delivered = deliveryResults.length > 0;
       return null;
diff --git a/src/gateway/server-node-events.ts b/src/gateway/server-node-events.ts
index ce1d699797f..7446d1e22cf 100644
--- a/src/gateway/server-node-events.ts
+++ b/src/gateway/server-node-events.ts
@@ -241,6 +241,7 @@ async function sendReceiptAck(params: {
     agentId,
     bestEffort: true,
     deps: createOutboundSendDeps(params.deps),
+    sessionKey: params.sessionKey,
   });
 }
 
diff --git a/src/infra/heartbeat-runner.ts b/src/infra/heartbeat-runner.ts
index 73c2fafb1ae..bd43092b92a 100644
--- a/src/infra/heartbeat-runner.ts
+++ b/src/infra/heartbeat-runner.ts
@@ -723,6 +723,7 @@ export async function runHeartbeatOnce(opts: {
       payloads: [{ text: heartbeatOkText }],
       agentId,
       deps: opts.deps,
+      sessionKey,
     });
     return true;
   };
@@ -928,6 +929,7 @@ export async function runHeartbeatOnce(opts: {
             ]),
       ],
       deps: opts.deps,
+      sessionKey,
     });
 
     // Record last delivered heartbeat payload for dedupe.
diff --git a/src/infra/outbound/message.ts b/src/infra/outbound/message.ts
index 30451b66959..1ae2a9246ae 100644
--- a/src/infra/outbound/message.ts
+++ b/src/infra/outbound/message.ts
@@ -233,6 +233,7 @@ export async function sendMessage(params: MessageSendParams): Promise<MessageSen
             mediaUrls: mirrorMediaUrls.length ? mirrorMediaUrls : undefined,
           }
         : undefined,
+      sessionKey: params.mirror?.sessionKey,
     });
 
     return {