fix(diagnostics): Back from a request's lines returns to the view it came from

Every filter change replaced the history entry, so Back after a request or
job pivot left the console altogether (the 0.90 notes promised otherwise).
A pivot follows a link and is its own entry now; the console reads the
landed entry back on popstate. The other filters still adjust in place.

frontend/src/components/AdminLogs.dom.test.tsx

@@ -124,6 +124,42 @@ describe("AdminLogs", () => {
     expect([url.get("lreq"), url.get("lgrp"), url.get("lq")]).toEqual(["req-00000001", null, null]);
   });
 
+  it("Back from a request's lines returns to the view the pivot was made from", async () => {
+    window.history.replaceState({ sfPage: "logs" }, "", "/?page=logs&lgrp=error&lq=boom");
+    const depth = window.history.length;
+    logsMock.mockResolvedValue({ items: [row(1)], accounts: {}, next_cursor: null });
+    renderConsole();
+    await waitFor(() => expect(lines()).toHaveLength(1));
+    fireEvent.click(lines()[0]!);
+    fireEvent.click(screen.getByRole("button", { name: "req-00000001" }));
+    await waitFor(() =>
+      expect(screen.getByText("adminLogs.pivotRequest:req-00000001")).toBeTruthy(),
+    );
+    expect(window.history.length).toBe(depth + 1);
+
+    await act(async () => {
+      const landed = new Promise((resolve) =>
+        window.addEventListener("popstate", resolve, { once: true }),
+      );
+      window.history.back();
+      await landed;
+    });
+
+    await waitFor(() =>
+      expect(logsMock).toHaveBeenLastCalledWith(
+        expect.objectContaining({
+          request_id: undefined,
+          levels: ["ERROR", "CRITICAL"],
+          q: "boom",
+        }),
+        null,
+      ),
+    );
+    expect(screen.queryByText("adminLogs.pivotRequest:req-00000001")).toBeNull();
+    const url = new URLSearchParams(window.location.search);
+    expect([url.get("lreq"), url.get("lgrp"), url.get("lq")]).toEqual([null, "error", "boom"]);
+  });
+
   it("keeps the account in use offered when the facets no longer count it", async () => {
     window.history.replaceState(null, "", "/?page=logs&lu=7");
     logsMock.mockResolvedValue({ items: [], accounts: {}, next_cursor: null });

frontend/src/components/AdminLogs.tsx

@@ -1,4 +1,4 @@
-import { useMemo, useRef, useState } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import {
   keepPreviousData,
@@ -11,6 +11,7 @@ import { Copy, Radio, Search, X } from "lucide-react";
 import { api, type LogFacet, type LogQuery, type ServerLogRow } from "../lib/api";
 import { copyText } from "../lib/clipboard";
 import { formatDateTime } from "../lib/format";
+import { nextNavId, notifyNav, rememberNavPosition } from "../lib/history";
 import { LEVEL_GROUPS, type LevelGroup } from "../lib/log";
 import {
   DEFAULT_LOGS_STATE,
@@ -23,6 +24,7 @@ import {
 import { notify } from "../lib/notifications";
 import { qk } from "../lib/queryKeys";
 import { useDebounced } from "../lib/useDebounced";
+import { urlWithParams } from "../lib/urlState";
 import { useUrlMirror } from "../lib/useUrlMirror";
 import LogLine from "./LogLine";
 import NavGrid from "./ui/NavGrid";
@@ -82,6 +84,15 @@ export default function AdminLogs() {
   const [open, setOpen] = useState<number | null>(null);
   const q = useDebounced(state.q, 300);
   useUrlMirror(logsParamUpdates(state));
+  // Back/Forward lands on another view of the console (a pivot pushed one, below): read it back.
+  useEffect(() => {
+    const onPop = () => {
+      setOpen(null);
+      setState(logsParamsToState(new URLSearchParams(window.location.search)));
+    };
+    window.addEventListener("popstate", onPop);
+    return () => window.removeEventListener("popstate", onPop);
+  }, []);
 
   const update = (patch: Partial<LogsUrlState>) => {
     setOpen(null);
@@ -184,9 +195,18 @@ export default function AdminLogs() {
     return facets.data ? sum(levels.filter((f) => inGroup.includes(f.value))) : undefined;
   };
 
+  // A pivot follows a link to another view, so it is its own history entry and Back returns to the
+  // view it was made from. The other filters are adjustments of the view on screen and replace it.
   const pivot = (patch: Pick<LogsUrlState, "requestId" | "jobId">) => {
     setLive(false);
-    update({ ...PIVOT_RESET, ...patch });
+    const next = { ...state, ...PIVOT_RESET, ...patch };
+    window.history.pushState(
+      { ...rememberNavPosition(), sfScroll: nextNavId() },
+      "",
+      urlWithParams(logsParamUpdates(next)),
+    );
+    notifyNav();
+    update(next);
   };
 
   // "Any", then what the facet counted. The value in use stays offered even at zero — under the