diff --git a/plugin/lvmh-agent.ts b/plugin/lvmh-agent.ts
index 0dd7d70..fe6d4b5 100644
--- a/plugin/lvmh-agent.ts
+++ b/plugin/lvmh-agent.ts
@@ -43,6 +43,9 @@ const ENV_URL: string = "LVMH_URL";
 const ENV_TOKEN: string = "LVMH_TOKEN";
 const ENV_AGENT: string = "LVMH_AGENT";
 const ENV_REPO: string = "LVMH_REPO";
+/** Daemon-assigned session id for spawned containers: takes precedence over
+ *  pi's own session id so web prompts route to the id /api/spawn returned. */
+const ENV_SESSION_ID: string = "LVMH_SESSION_ID";
 
 const SEND_QUEUE_MAX: number = 1000;
 const REPLAY_BUFFER_MAX: number = 10000;
@@ -619,6 +622,11 @@ export default function (pi: ExtensionAPI): void {
 			log("no session id; lvmh mirroring disabled for this session");
 			return;
 		}
+		const assignedId = process.env[ENV_SESSION_ID];
+		if (typeof assignedId === "string" && assignedId.length > 0) {
+			// Spawned container session: report the daemon-assigned id.
+			sessionId = assignedId;
+		}
 		if (sessionId !== currentSessionId) {
 			sendQueue = [];
 			replayBuf = [];