fix(lineage): clear stale focused graph during navigation

frontend/src/App.test.tsx

@@ -2253,13 +2253,17 @@ describe("App, authenticated", () => {
       "no_comparison_group" as const,
       "No other visible posts share this comparison group yet. Request reconstruction after more posts arrive, or read Keyman and evaluation.",
     ],
-  ])("explains an empty focused Event Lineage graph: %s", async (lineageIsolationReason, message) => {
-    stubBackend({ lineageIsolationReason });
-    render(<App showLabPanels />);
-    await userEvent.click(await screen.findByRole("button", { name: "View post: Public post" }));
-    expect(await screen.findByText(message)).toBeInTheDocument();
-    expect(screen.queryByText("No linked posts yet.")).not.toBeInTheDocument();
-  });
+  ])(
+    "explains an empty focused Event Lineage graph: %s",
+    async (lineageIsolationReason, message) => {
+      stubBackend({ lineageIsolationReason });
+      render(<App showLabPanels />);
+      await userEvent.click(await screen.findByRole("button", { name: "View post: Public post" }));
+      expect(await screen.findByText(message)).toBeInTheDocument();
+      expect(screen.queryByText("No linked posts yet.")).not.toBeInTheDocument();
+    },
+    15_000,
+  );
 
   it("shows an embedded invoice image instead of the raw base64 string", async () => {
     const tinyPng =

frontend/src/App.tsx

@@ -1,6 +1,7 @@
 import { AdminPanel } from "./components/AdminPanel";
 import { LeftoverPairList } from "./components/LeftoverPairList";
 import { WorkspaceCalendar } from "./components/WorkspaceCalendar";
+import { focusedGraphMustReset } from "./focusedGraphSelection";
 
 import { useCallback, useEffect, useRef, useState, type ReactNode } from "react";
 import { useAuth } from "react-oidc-context";
@@ -3823,7 +3824,6 @@ function PostList({
   onPostOpened?: () => void;
 }) {
   const [posts, setPosts] = useState<PostSummary[] | null>(null);
-  const [graph, setGraph] = useState<LineageGraph | null>(null);
   const [focusedGraph, setFocusedGraph] = useState<LineageGraph | null>(null);
   const [error, setError] = useState<string | null>(null);
   const [selectedPostId, setSelectedPostId] = useState<string | null>(null);
@@ -3886,8 +3886,10 @@ function PostList({
   }
 
   function selectPost(postId: string, options?: SelectPostOptions) {
+    if (focusedGraphMustReset(selectedPostId, postId)) {
+      setFocusedGraph(null);
+    }
     setSelectedPostId(postId);
-    setFocusedGraph(null);
     setOpenedAfterCutoff(Boolean(options?.liveAfterCutoff));
     setOpenedCutoffIso(options?.knowledgeCutoff ?? null);
     setOpenedFromReportMember(Boolean(options?.fromReportMember));
@@ -3955,7 +3957,6 @@ function PostList({
   }, [loadPostPage]);
 
   useEffect(() => {
-    fetchLineageGraph(accessToken).then(setGraph).catch(() => setGraph({ nodes: [], edges: [] }));
     fetchMe(accessToken)
       .then((me) => {
         setCanRebuild(me.permission_codes.includes("post_admin"));
@@ -3974,6 +3975,7 @@ function PostList({
       setFocusedGraph(null);
       return;
     }
+    setFocusedGraph(null);
     let active = true;
     fetchLineageGraph(accessToken, selectedPostId)
       .then((nextGraph) => {
@@ -3992,7 +3994,6 @@ function PostList({
     setRebuildError(null);
     try {
       await rebuildLineage(accessToken);
-      setGraph(await fetchLineageGraph(accessToken));
     } catch (err) {
       setRebuildError(String(err));
     } finally {
@@ -4304,7 +4305,7 @@ function PostList({
           postId={selectedPostId}
           accessToken={accessToken}
           canExtract={canRebuild}
-          graph={focusedGraph ?? graph}
+          graph={focusedGraph}
           liveBodyWarning={
             openedAfterCutoff ? analysisRunOpenedBodyWarning(openedCutoffIso) : null
           }

frontend/src/components/WorkspaceCalendar.tsx

@@ -33,7 +33,7 @@ export function WorkspaceCalendar({
       <section className="popup-section" aria-labelledby={`${headingId}-observed`}>
         <h3 id={`${headingId}-observed`}>{t("Observed calendar events")}</h3>
         {events.length === 0 ? (
-          <p className="popup-placeholder" role="status">
+          <p className="popup-placeholder">
             {naruonAvailable
               ? t("No observed calendar events are available.")
               : failClosedCopy}

frontend/src/focusedGraphSelection.test.ts

@@ -0,0 +1,9 @@
+import { describe, expect, it } from "vitest";
+import { focusedGraphMustReset } from "./focusedGraphSelection";
+
+describe("focusedGraphMustReset", () => {
+  it("retains a loaded graph when the already-open post is selected again", () => {
+    expect(focusedGraphMustReset("post-1", "post-1")).toBe(false);
+    expect(focusedGraphMustReset("post-1", "post-2")).toBe(true);
+  });
+});

frontend/src/focusedGraphSelection.ts

@@ -0,0 +1,4 @@
+/** Return whether selecting a post requires discarding the currently focused graph. */
+export function focusedGraphMustReset(currentPostId: string | null, nextPostId: string): boolean {
+  return currentPostId !== nextPostId;
+}