fix(web): take the Session's elapsed time from Trace timestamps, so a reload stops restarting it (#124)

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/web/src/api/endpoints.ts

@@ -71,7 +71,7 @@ import type {
   VersionResponse,
   WorkspaceFilesResponse,
 } from "@prismshadow/penguin-server/api";
-import { apiFetch } from "./client";
+import { apiFetch, apiFetchWithMeta } from "./client";
 
 // Auth & user -----------------------------------------------------------------
 
@@ -246,8 +246,17 @@ export const patchSession = (sessionId: string, body: SessionPatchRequest) =>
 export const deleteSession = (sessionId: string) =>
   apiFetch<void>(`/api/sessions/${encodeURIComponent(sessionId)}`, { method: "DELETE" });
 
+/**
+ * History rebuild. Carries the server's clock at read time (see ApiFetchMeta.serverNowMs)
+ * alongside the messages: a Task still running has no Trace entry for the event currently in
+ * flight, so its elapsed can only be measured by differencing this against the Task's first
+ * message timestamp — both server-side values, so no client clock offset enters the result
+ * (see pushMessages).
+ */
 export const getMessages = (sessionId: string) =>
-  apiFetch<MessagesResponse>(`/api/sessions/${encodeURIComponent(sessionId)}/messages`);
+  apiFetchWithMeta<MessagesResponse>(
+    `/api/sessions/${encodeURIComponent(sessionId)}/messages`,
+  ).then(({ data, serverNowMs }) => ({ ...data, serverNowMs }));
 
 // Task execution, approval, abort, compaction ------------------------------------------------------