feat(webui): segment transcript storage

webui/src/lib/api.ts

@@ -124,12 +124,27 @@ export async function listSessions(
 }
 
 /** Disk-backed WebUI display thread snapshot (separate from agent session). */
+export interface FetchWebuiThreadOptions {
+  limit?: number;
+  direction?: "latest";
+  before?: string | null;
+}
+
 export async function fetchWebuiThread(
   token: string,
   key: string,
+  optionsOrBase?: FetchWebuiThreadOptions | string,
   base: string = "",
 ): Promise<WebuiThreadPersistedPayload | null> {
-  const url = `${base}/api/sessions/${encodeURIComponent(key)}/webui-thread`;
+  const options = typeof optionsOrBase === "string" ? undefined : optionsOrBase;
+  const resolvedBase = typeof optionsOrBase === "string" ? optionsOrBase : base;
+  const params = new URLSearchParams();
+  if (options?.limit !== undefined) params.set("limit", String(options.limit));
+  if (options?.direction) params.set("direction", options.direction);
+  if (options?.before) params.set("before", options.before);
+  const query = params.toString();
+  const suffix = query ? `?${query}` : "";
+  const url = `${resolvedBase}/api/sessions/${encodeURIComponent(key)}/webui-thread${suffix}`;
   const res = await fetchWithTimeout(url, {
     headers: { Authorization: `Bearer ${token}` },
     credentials: "same-origin",

webui/src/lib/types.ts

@@ -857,12 +857,21 @@ export interface OutboundMcpPresetMention {
 }
 
 /** Response shape for ``GET .../webui-thread`` (server-built transcript replay). */
+export interface WebuiThreadPagePayload {
+  before_cursor?: string | null;
+  has_more_before?: boolean;
+  loaded_message_count?: number;
+  total_known_message_count?: number;
+  user_message_offset?: number;
+}
+
 export interface WebuiThreadPersistedPayload {
   schemaVersion: number;
   sessionKey?: string;
   savedAt?: string;
   messages: UIMessage[];
   fork_boundary_message_count?: number;
+  page?: WebuiThreadPagePayload;
   workspace_scope?: WorkspaceScopePayload;
 }