diff --git a/src/gateway/session-utils.ts b/src/gateway/session-utils.ts
index 2f89a956b44..519682cd4e1 100644
--- a/src/gateway/session-utils.ts
+++ b/src/gateway/session-utils.ts
@@ -381,9 +381,9 @@ function resolveRuntimeChildSessionKeys(
 ): string[] | undefined {
   const childSessionKeys = new Set<string>();
   const controllerKey = controllerSessionKey.trim();
-  const runs =
-    subagentRuns?.runsByControllerSessionKey.get(controllerKey) ??
-    listSubagentRunsForController(controllerSessionKey);
+  const runs = subagentRuns
+    ? (subagentRuns.runsByControllerSessionKey.get(controllerKey) ?? [])
+    : listSubagentRunsForController(controllerSessionKey);
   for (const entry of runs) {
     const childSessionKey = normalizeOptionalString(entry.childSessionKey);
     if (!childSessionKey) {
@@ -1919,11 +1919,21 @@ export function listSessionsFromStore(params: {
   const now = Date.now();
   const sessionListTranscriptUsageMaxBytes = 64 * 1024;
   const sessionListTranscriptFieldRows = 100;
-  const rowContext = buildSessionListRowContext({ store, now });
+  let rowContext: SessionListRowContext | undefined;
+  const getRowContext = () => {
+    rowContext ??= buildSessionListRowContext({ store, now });
+    return rowContext;
+  };
   const includeDerivedTitles = opts.includeDerivedTitles === true;
   const includeLastMessage = opts.includeLastMessage === true;
+  const hasSpawnedByFilter = typeof opts.spawnedBy === "string" && opts.spawnedBy.length > 0;
 
-  const entries = filterAndSortSessionEntries({ store, opts, now, rowContext });
+  const entries = filterAndSortSessionEntries({
+    store,
+    opts,
+    now,
+    rowContext: hasSpawnedByFilter ? getRowContext() : undefined,
+  });
 
   const sessions = entries.map(([key, entry], index) => {
     const includeTranscriptFields = index < sessionListTranscriptFieldRows;
@@ -1938,8 +1948,8 @@ export function listSessionsFromStore(params: {
       includeDerivedTitles: includeTranscriptFields && includeDerivedTitles,
       includeLastMessage: includeTranscriptFields && includeLastMessage,
       transcriptUsageMaxBytes: sessionListTranscriptUsageMaxBytes,
-      storeChildSessionsByKey: rowContext.storeChildSessionsByKey,
-      rowContext,
+      storeChildSessionsByKey: getRowContext().storeChildSessionsByKey,
+      rowContext: getRowContext(),
     });
   });
 
@@ -1973,11 +1983,21 @@ export async function listSessionsFromStoreAsync(params: {
   const now = Date.now();
   const sessionListTranscriptUsageMaxBytes = 64 * 1024;
   const sessionListTranscriptFieldRows = 100;
-  const rowContext = buildSessionListRowContext({ store, now });
+  let rowContext: SessionListRowContext | undefined;
+  const getRowContext = () => {
+    rowContext ??= buildSessionListRowContext({ store, now });
+    return rowContext;
+  };
   const includeDerivedTitles = opts.includeDerivedTitles === true;
   const includeLastMessage = opts.includeLastMessage === true;
+  const hasSpawnedByFilter = typeof opts.spawnedBy === "string" && opts.spawnedBy.length > 0;
 
-  const entries = filterAndSortSessionEntries({ store, opts, now, rowContext });
+  const entries = filterAndSortSessionEntries({
+    store,
+    opts,
+    now,
+    rowContext: hasSpawnedByFilter ? getRowContext() : undefined,
+  });
 
   const sessions: GatewaySessionRow[] = [];
   for (let i = 0; i < entries.length; i++) {
@@ -1994,8 +2014,8 @@ export async function listSessionsFromStoreAsync(params: {
       includeDerivedTitles: false,
       includeLastMessage: false,
       transcriptUsageMaxBytes: sessionListTranscriptUsageMaxBytes,
-      storeChildSessionsByKey: rowContext.storeChildSessionsByKey,
-      rowContext,
+      storeChildSessionsByKey: getRowContext().storeChildSessionsByKey,
+      rowContext: getRowContext(),
     });
     if (
       entry?.sessionId &&