fix(webui): stabilize live thread rendering and navigation

webui/src/lib/tool-traces.ts

@@ -0,0 +1,30 @@
+export function formatToolCallTrace(call: unknown): string | null {
+  if (!call || typeof call !== "object") return null;
+  const item = call as {
+    name?: unknown;
+    arguments?: unknown;
+    function?: { name?: unknown; arguments?: unknown };
+  };
+  const name =
+    typeof item.function?.name === "string"
+      ? item.function.name
+      : typeof item.name === "string"
+        ? item.name
+        : "";
+  if (!name) return null;
+  const args = item.function?.arguments ?? item.arguments;
+  if (typeof args === "string" && args.trim()) return `${name}(${args})`;
+  if (args && typeof args === "object") return `${name}(${JSON.stringify(args)})`;
+  return `${name}()`;
+}
+
+export function toolTraceLinesFromEvents(events: unknown): string[] {
+  if (!Array.isArray(events)) return [];
+  return events
+    .filter((event) => {
+      if (!event || typeof event !== "object") return false;
+      return (event as { phase?: unknown }).phase === "start";
+    })
+    .map(formatToolCallTrace)
+    .filter((trace): trace is string => !!trace);
+}

webui/src/lib/types.ts

@@ -53,6 +53,18 @@ export interface UIMessage {
   reasoningStreaming?: boolean;
 }
 
+export interface ToolProgressEvent {
+  version?: number;
+  phase?: "start" | "end" | "error" | string;
+  call_id?: string;
+  name?: string;
+  arguments?: unknown;
+  result?: unknown;
+  error?: unknown;
+  files?: unknown[];
+  embeds?: unknown[];
+}
+
 export interface ChatSummary {
   /** Server-side session key, e.g. ``websocket:abcd-...``. */
   key: string;
@@ -146,6 +158,7 @@ export type InboundEvent =
       reply_to?: string;
       media?: string[];
       media_urls?: Array<{ url: string; name?: string }>;
+      tool_events?: ToolProgressEvent[];
       /** Present when the frame is an agent breadcrumb (e.g. tool hint,
        * generic progress line) rather than a conversational reply. */
       kind?: "tool_hint" | "progress" | "reasoning";