diff --git a/ui/src/components/IssuesList.tsx b/ui/src/components/IssuesList.tsx
index a444a2dfd99..c19d76a9b25 100644
--- a/ui/src/components/IssuesList.tsx
+++ b/ui/src/components/IssuesList.tsx
@@ -177,6 +177,15 @@ function sortIssues(issues: Issue[], state: IssueViewState): Issue[] {
   return sorted;
 }
 
+function issueMatchesLocalSearch(issue: Issue, normalizedSearch: string): boolean {
+  if (!normalizedSearch) return true;
+  return [
+    issue.identifier,
+    issue.title,
+    issue.description,
+  ].some((value) => value?.toLowerCase().includes(normalizedSearch));
+}
+
 /* ── Component ── */
 
 interface Agent {
@@ -208,6 +217,7 @@ interface IssuesListProps {
   initialWorkspaces?: string[];
   initialSearch?: string;
   searchFilters?: Omit<IssueListRequestFilters, "q" | "projectId" | "limit" | "includeRoutineExecutions">;
+  searchWithinLoadedIssues?: boolean;
   baseCreateIssueDefaults?: Record<string, unknown>;
   createIssueLabel?: string;
   enableRoutineVisibilityFilter?: boolean;
@@ -293,6 +303,7 @@ export function IssuesList({
   initialWorkspaces,
   initialSearch,
   searchFilters,
+  searchWithinLoadedIssues = false,
   baseCreateIssueDefaults,
   createIssueLabel,
   enableRoutineVisibilityFilter = false,
@@ -393,7 +404,7 @@ export function IssuesList({
         ...searchFilters,
         ...(enableRoutineVisibilityFilter ? { includeRoutineExecutions: true } : {}),
       }),
-    enabled: !!selectedCompanyId && normalizedIssueSearch.length > 0,
+    enabled: !!selectedCompanyId && normalizedIssueSearch.length > 0 && !searchWithinLoadedIssues,
     placeholderData: (previousData) => previousData,
   });
   const boardIssueQueries = useQueries({
@@ -417,7 +428,7 @@ export function IssuesList({
           limit: ISSUE_BOARD_COLUMN_RESULT_LIMIT,
           ...(enableRoutineVisibilityFilter ? { includeRoutineExecutions: true } : {}),
         }),
-      enabled: !!selectedCompanyId && viewState.viewMode === "board",
+      enabled: !!selectedCompanyId && viewState.viewMode === "board" && !searchWithinLoadedIssues,
       placeholderData: (previousData: Issue[] | undefined) => previousData,
     })),
   });
@@ -598,7 +609,7 @@ export function IssuesList({
   }, [issues]);
 
   const boardIssues = useMemo(() => {
-    if (viewState.viewMode !== "board") return null;
+    if (viewState.viewMode !== "board" || searchWithinLoadedIssues) return null;
     const merged = new Map<string, Issue>();
     let isPending = false;
     for (const query of boardIssueQueries) {
@@ -609,13 +620,17 @@ export function IssuesList({
     }
     if (merged.size > 0) return [...merged.values()];
     return isPending ? issues : [];
-  }, [boardIssueQueries, issues, viewState.viewMode]);
+  }, [boardIssueQueries, issues, searchWithinLoadedIssues, viewState.viewMode]);
 
   const filtered = useMemo(() => {
-    const sourceIssues = boardIssues ?? (normalizedIssueSearch.length > 0 ? searchedIssues : issues);
-    const filteredByControls = applyIssueFilters(sourceIssues, viewState, currentUserId, enableRoutineVisibilityFilter);
+    const useRemoteSearch = normalizedIssueSearch.length > 0 && !searchWithinLoadedIssues;
+    const sourceIssues = boardIssues ?? (useRemoteSearch ? searchedIssues : issues);
+    const searchScopedIssues = normalizedIssueSearch.length > 0 && searchWithinLoadedIssues
+      ? sourceIssues.filter((issue) => issueMatchesLocalSearch(issue, normalizedIssueSearch))
+      : sourceIssues;
+    const filteredByControls = applyIssueFilters(searchScopedIssues, viewState, currentUserId, enableRoutineVisibilityFilter);
     return sortIssues(filteredByControls, viewState);
-  }, [boardIssues, issues, searchedIssues, viewState, normalizedIssueSearch, currentUserId, enableRoutineVisibilityFilter]);
+  }, [boardIssues, issues, searchedIssues, searchWithinLoadedIssues, viewState, normalizedIssueSearch, currentUserId, enableRoutineVisibilityFilter]);
 
   const { data: labels } = useQuery({
     queryKey: queryKeys.issues.labels(selectedCompanyId!),
@@ -913,7 +928,7 @@ export function IssuesList({
 
       {isLoading && <PageSkeleton variant="issues-list" />}
       {error && <p className="text-sm text-destructive">{error.message}</p>}
-      {normalizedIssueSearch.length > 0 && searchedIssues.length === ISSUE_SEARCH_RESULT_LIMIT && (
+      {!searchWithinLoadedIssues && normalizedIssueSearch.length > 0 && searchedIssues.length === ISSUE_SEARCH_RESULT_LIMIT && (
         <p className="text-xs text-muted-foreground">
           Showing up to {ISSUE_SEARCH_RESULT_LIMIT} matches. Refine the search to narrow further.
         </p>
diff --git a/ui/src/lib/issue-tree.test.ts b/ui/src/lib/issue-tree.test.ts
index 75d38f874a1..955f3a0d989 100644
--- a/ui/src/lib/issue-tree.test.ts
+++ b/ui/src/lib/issue-tree.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 import type { Issue } from "@paperclipai/shared";
-import { buildIssueTree, countDescendants } from "./issue-tree";
+import { buildIssueTree, countDescendants, filterIssueDescendants } from "./issue-tree";
 
 function makeIssue(id: string, parentId: string | null = null): Issue {
   return {
@@ -128,3 +128,33 @@ describe("countDescendants", () => {
     expect(countDescendants("nonexistent", childMap)).toBe(0);
   });
 });
+
+describe("filterIssueDescendants", () => {
+  it("returns only children and deeper descendants of the requested root", () => {
+    const root = makeIssue("root");
+    const child = makeIssue("child", "root");
+    const grandchild = makeIssue("grandchild", "child");
+    const unrelatedParent = makeIssue("other");
+    const unrelatedChild = makeIssue("other-child", "other");
+
+    expect(filterIssueDescendants("root", [
+      root,
+      child,
+      grandchild,
+      unrelatedParent,
+      unrelatedChild,
+    ]).map((issue) => issue.id)).toEqual(["child", "grandchild"]);
+  });
+
+  it("handles stale broad issue-list responses without requiring the root in the list", () => {
+    const child = makeIssue("child", "root");
+    const grandchild = makeIssue("grandchild", "child");
+    const globalIssue = makeIssue("global");
+
+    expect(filterIssueDescendants("root", [
+      globalIssue,
+      child,
+      grandchild,
+    ]).map((issue) => issue.id)).toEqual(["child", "grandchild"]);
+  });
+});
diff --git a/ui/src/lib/issue-tree.ts b/ui/src/lib/issue-tree.ts
index e88709ed120..25707053146 100644
--- a/ui/src/lib/issue-tree.ts
+++ b/ui/src/lib/issue-tree.ts
@@ -34,3 +34,39 @@ export function countDescendants(id: string, childMap: Map<string, Issue[]>): nu
   const children = childMap.get(id) ?? [];
   return children.reduce((sum, c) => sum + 1 + countDescendants(c.id, childMap), 0);
 }
+
+/**
+ * Filters a flat issue list to only descendants of `rootId`.
+ *
+ * This is intentionally useful even when the list contains unrelated issues:
+ * stale servers may ignore newer descendant-scoped query params, and the UI
+ * must still avoid rendering global issue data in a sub-issue panel.
+ */
+export function filterIssueDescendants(rootId: string, items: Issue[]): Issue[] {
+  const childrenByParentId = new Map<string, Issue[]>();
+  for (const item of items) {
+    if (!item.parentId) continue;
+    const siblings = childrenByParentId.get(item.parentId) ?? [];
+    siblings.push(item);
+    childrenByParentId.set(item.parentId, siblings);
+  }
+
+  const descendants: Issue[] = [];
+  const seen = new Set<string>([rootId]);
+  let frontier = [rootId];
+
+  while (frontier.length > 0) {
+    const nextFrontier: string[] = [];
+    for (const parentId of frontier) {
+      for (const child of childrenByParentId.get(parentId) ?? []) {
+        if (seen.has(child.id)) continue;
+        seen.add(child.id);
+        descendants.push(child);
+        nextFrontier.push(child.id);
+      }
+    }
+    frontier = nextFrontier;
+  }
+
+  return descendants;
+}
diff --git a/ui/src/pages/IssueDetail.tsx b/ui/src/pages/IssueDetail.tsx
index 58840877519..a4345e0a616 100644
--- a/ui/src/pages/IssueDetail.tsx
+++ b/ui/src/pages/IssueDetail.tsx
@@ -98,6 +98,7 @@ import { Textarea } from "@/components/ui/textarea";
 import { formatIssueActivityAction } from "@/lib/activity-format";
 import { buildIssuePropertiesPanelKey } from "../lib/issue-properties-panel-key";
 import { shouldRenderRichSubIssuesSection } from "../lib/issue-detail-subissues";
+import { filterIssueDescendants } from "../lib/issue-tree";
 import { buildSubIssueDefaultsForViewer } from "../lib/subIssueDefaults";
 import {
   Activity as ActivityIcon,
@@ -1286,8 +1287,11 @@ export function IssueDetail() {
     [issue?.project, issue?.projectId, orderedProjects],
   );
   const childIssues = useMemo(
-    () => [...rawChildIssues].sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime()),
-    [rawChildIssues],
+    () => {
+      const descendants = issue?.id ? filterIssueDescendants(issue.id, rawChildIssues) : rawChildIssues;
+      return [...descendants].sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime());
+    },
+    [issue?.id, rawChildIssues],
   );
   const liveIssueIds = useMemo(() => collectLiveIssueIds(companyLiveRuns), [companyLiveRuns]);
   const issuePanelKey = useMemo(
@@ -3134,6 +3138,7 @@ export function IssueDetail() {
             viewStateKey={`paperclip:issue-detail:${issue.id}:subissues-view`}
             issueLinkState={resolvedIssueDetailState ?? location.state}
             searchFilters={{ descendantOf: issue.id }}
+            searchWithinLoadedIssues
             baseCreateIssueDefaults={buildSubIssueDefaultsForViewer(issue, currentUserId)}
             createIssueLabel="Sub-issue"
             onUpdateIssue={handleChildIssueUpdate}