fix(frontend): hide model activity execution noise

frontend/src/shell/ModelActivityPanel.tsx

@@ -2,10 +2,21 @@ import { useLayoutEffect, useRef } from "react";
 import { X } from "lucide-react";
 import ReactMarkdown from "react-markdown";
 import remarkGfm from "remark-gfm";
-import type { ActivityEntry } from "../api/types";
+import type { ActivityEntry, ActivityKind } from "../api/types";
 import { useSessionStore } from "../store/sessionStore";
 import { Button } from "../components/ui/button";
 
+const VISIBLE_MODEL_ACTIVITY_KINDS: ReadonlySet<ActivityKind> = new Set([
+  "prompt",
+  "thinking",
+  "status",
+  "gate",
+]);
+
+export function isVisibleModelActivity(entry: ActivityEntry): boolean {
+  return VISIBLE_MODEL_ACTIVITY_KINDS.has(entry.kind);
+}
+
 export function isNearBottom(
   el: Pick<HTMLElement, "scrollHeight" | "clientHeight" | "scrollTop">,
   threshold = 48,
@@ -85,16 +96,19 @@ function ActivityRow({ entry }: { entry: ActivityEntry }) {
   );
 }
 
-/** Left drawer showing the complete in-memory model activity timeline. */
+/** Left drawer showing the user-facing projection of the in-memory model activity timeline. */
 export function ModelActivityPanel({ onClose }: { onClose: () => void }) {
   const activityLog = useSessionStore((s) => s.activityLog);
+  const visibleActivity = activityLog.filter(isVisibleModelActivity);
+  const visibleCount = visibleActivity.length;
+  const visibleTail = visibleActivity.at(-1);
   const scrollRef = useRef<HTMLDivElement>(null);
   const followRef = useRef(true);
 
   useLayoutEffect(() => {
     const viewport = scrollRef.current;
     if (viewport && followRef.current) viewport.scrollTop = viewport.scrollHeight;
-  }, [activityLog]);
+  }, [visibleCount, visibleTail]);
 
   return (
     <aside className="flex w-2/5 shrink-0 flex-col border-r border-border bg-sidebar">
@@ -114,10 +128,10 @@ export function ModelActivityPanel({ onClose }: { onClose: () => void }) {
           followRef.current = isNearBottom(event.currentTarget);
         }}
       >
-        {activityLog.length === 0 ? (
+        {visibleActivity.length === 0 ? (
           <p className="py-3 text-sm text-muted-foreground">No activity yet.</p>
         ) : (
-          activityLog.map((entry, index) => (
+          visibleActivity.map((entry, index) => (
             <ActivityRow key={`${index}-${entry.toolCallId ?? entry.kind}`} entry={entry} />
           ))
         )}