v1.11: opencode-style compaction port

- compaction.ts: usable/isOverflow/estimate/turns/select/buildPrompt/process
- compaction-prompt.ts: SUMMARY_TEMPLATE verbatim from opencode
- schema: messages.{compacted_at,summary,tail_start_id} + chats.needs_compaction
- inference: auto-trigger on overflow, pre-fetch compaction before next turn
- /compact slash command rewired to new path
- WS: chat_status working/idle around compaction + compacted frame
- frontend: SummaryCard + sonner toast on compacted
- 24 unit tests for pure functions

apps/web/src/components/MessageBubble.tsx

@@ -537,7 +537,70 @@ function CompactCard({ message, sessionChats }: { message: Message; sessionChats
   );
 }
 
+// v1.11 anchored rolling summary. Inserted by services/compaction.ts as a
+// role='assistant', summary=true row. Distinct from legacy CompactCard
+// (which renders the kind='compact' system rows produced by v1.10 /compact).
+// Collapsed by default; header shows the timestamp; body renders the
+// summary markdown when expanded. Copy button matches CompactCard's affordance.
+function SummaryCard({ message }: { message: Message }) {
+  const [expanded, setExpanded] = useState(false);
+  const [copied, setCopied] = useState(false);
+
+  // Use finished_at when available (that's when the summary actually landed);
+  // fall back to created_at for any row missing it. Both are ISO strings.
+  const ts = message.finished_at ?? message.created_at;
+  const headerTs = ts ? new Date(ts).toLocaleString() : '';
+
+  async function handleCopy() {
+    try {
+      await navigator.clipboard.writeText(message.content);
+      setCopied(true);
+      setTimeout(() => setCopied(false), 1200);
+      toast.success('Summary copied to clipboard');
+    } catch {
+      toast.error('Copy failed');
+    }
+  }
+
+  return (
+    <div className="rounded-lg border border-primary/30 bg-primary/5 text-sm">
+      <div className="flex items-center gap-2 px-3 py-2">
+        <button
+          type="button"
+          onClick={() => setExpanded(!expanded)}
+          className="flex items-center gap-1.5 flex-1 min-w-0 text-left text-muted-foreground hover:text-foreground"
+        >
+          {expanded ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
+          <span className="text-xs font-medium truncate">
+            Compacted summary — {headerTs}
+          </span>
+        </button>
+        <button
+          type="button"
+          onClick={() => void handleCopy()}
+          className="p-1 rounded hover:bg-muted text-muted-foreground"
+          aria-label="Copy summary"
+          title="Copy summary"
+        >
+          {copied ? <Check size={12} /> : <Copy size={12} />}
+        </button>
+      </div>
+      {expanded && (
+        <div className="px-3 pb-3 text-xs leading-relaxed border-t pt-2">
+          <MarkdownBody content={message.content} />
+        </div>
+      )}
+    </div>
+  );
+}
+
 export function MessageBubble({ message, sessionChats, capHitInfo }: Props) {
+  // v1.11: anchored rolling summary row. Checked BEFORE the kind==='compact'
+  // branch because summary=true never coexists with kind='compact' (new
+  // compactions emit role='assistant' rows with kind='message'+summary=true).
+  if (message.summary) {
+    return <SummaryCard message={message} />;
+  }
   if (message.kind === 'compact') {
     return <CompactCard message={message} sessionChats={sessionChats} />;
   }