make the editable tab name survive refreshes

sessionStorage is the per-tab store — separate per tab, survives reload and
navigation, dies with the tab. The route title is derived rather than assigned,
so navigating no longer wipes a name you typed.

Duplicating a tab clones sessionStorage, so a `navigate` that arrives already
holding a name is treated as a clone and drops it; fails soft.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/chat-ui-walkthrough.md

@@ -397,6 +397,53 @@ server code, not clicked through.
 
 ---
 
+## 16. The tab you named stays named
+
+`src/apps/officer-web/state/usePageTitle.ts`, `…/Layout/Header/Header.tsx`
+
+The title in the middle of the header has been editable for a while, and it renames the browser tab as
+you type — which is genuinely useful once you have six Officer tabs open and every one of them says
+"Chat". It just didn't last. Two separate reasons: the name lived only in React Query, so a refresh
+took it with the page; and `usePageTitleSync` had an effect that reset the title to the route default on
+every navigation, so clicking anything at all wiped it even without a refresh.
+
+**There is no tab id in the browser.** `chrome.tabs` gives an extension one, but page scripts are
+deliberately not allowed to know which tab they are in, or that other tabs exist — it's the same
+boundary that stops a page enumerating your windows. So there is no id to key the name on.
+
+There doesn't need to be: **`sessionStorage` *is* the per-tab store.** It's separate per tab, it
+survives a refresh and in-place navigation, and it's discarded when the tab closes. That is exactly the
+lifetime a tab name wants. (`localStorage` would be wrong in the obvious way — every tab would share
+one name, which is the problem, not the fix.)
+
+So the name is read from `sessionStorage` at module load and mirrored into a `useGlobal` entry; the
+React Query copy is what re-renders the header, and the storage copy is what survives the reload. The
+route title is no longer *assigned* to the state, it's **derived** — `label ?? titleForPath(pathname)`.
+Navigation therefore retitles the tab by itself when you haven't named it, and leaves it alone when you
+have. Clearing the field is the one way back to the route name, and there's no third state to get stuck
+in.
+
+**The one hole is duplicate-tab**, which you use constantly — and duplicating a tab clones its
+sessionStorage, so the copy would open wearing the original's name. Two tabs called "Platform Arch" is
+precisely what naming one was meant to prevent. `performance.getEntriesByType('navigation')[0].type`
+separates the cases: a refresh reports `reload`, a duplicate reports `navigate`. So a `navigate` that
+arrives already holding a name did not earn it, and the name is dropped. A brand-new tab is `navigate`
+too but has nothing stored, so it's untouched.
+
+That check **fails soft on purpose**: if the timing entry is missing, or some browser labels duplication
+differently, the copy just keeps the name — redundant, not wrong. Nothing else about the tab changes.
+
+The header input also became a draft committed on blur/Enter rather than a live write. It wrote every
+keystroke before, which was fine while the title was a plain string; now that an empty field means "use
+the route name", deleting the last character would have snapped the input to "Chat" under the cursor.
+Escape discards the draft.
+
+**Not verified:** the duplicate-tab navigation type, in an actual browser. The rest — that the name
+survives a refresh and a navigation — follows from sessionStorage's specified behaviour, but the clone
+heuristic is the part I could only reason about.
+
+---
+
 ## Things noticed and deliberately left alone
 
 - **`useChatWebSocket` silently ignores unparseable frames.** That one is intentional and the comment

src/apps/officer-web/Screens/Dashboard/Layout/Header/Header.tsx

@@ -11,29 +11,39 @@ import { RescanButton } from '../Rescan/RescanButton';
 import { usePageTitle } from '@/state/usePageTitle';
 // import { BugReportButton } from '../BugReport/BugReportButton';
 
-// Center title: click to rename this browser tab (per-tab, not persisted).
+// Center title: click to rename this browser tab. The name is kept in sessionStorage, so it survives a
+// refresh and navigation and dies with the tab — see usePageTitle.
 function EditablePageTitle() {
-  const [title, setTitle] = usePageTitle();
-  const [editing, setEditing] = useState(false);
+  const [title, rename] = usePageTitle();
+  const [draft, setDraft] = useState<string | null>(null);
 
-  if (editing) {
+  // The edit is a draft committed on blur/Enter rather than a live write. Writing every keystroke was
+  // fine while the title was a plain string, but an empty field now means "use the route name", so
+  // deleting the last character would snap the input to "Chat" underneath the cursor.
+  if (draft !== null) {
     return (
       <input
         autoFocus
-        value={title}
-        onChange={(ev) => setTitle(ev.target.value)}
-        onBlur={() => setEditing(false)}
-        onKeyDown={(ev) => {
-          if (ev.key === 'Enter' || ev.key === 'Escape') setEditing(false);
+        value={draft}
+        onChange={(ev) => setDraft(ev.target.value)}
+        onBlur={() => {
+          rename(draft);
+          setDraft(null);
         }}
+        onKeyDown={(ev) => {
+          if (ev.key === 'Enter') ev.currentTarget.blur();
+          if (ev.key === 'Escape') setDraft(null); // discard, keeping whatever the tab was called
+        }}
+        aria-label="Tab name"
+        placeholder={title}
         className="pointer-events-auto max-w-[50vw] border-b border-[#1d2724]/40 bg-transparent text-center text-base font-bold text-[#1d2724] outline-none md:text-xl"
       />
     );
   }
   return (
     <button
-      onClick={() => setEditing(true)}
-      title="Click to rename this tab"
+      onClick={() => setDraft(title)}
+      title="Click to rename this tab — clear it to go back to the page name"
       className="pointer-events-auto max-w-[50vw] cursor-text truncate text-base font-bold text-[#1d2724] transition-opacity hover:opacity-70 md:text-xl"
     >
       {title}

src/apps/officer-web/state/usePageTitle.ts

@@ -1,4 +1,4 @@
-import { useEffect } from 'react';
+import { useCallback, useEffect } from 'react';
 import { useLocation } from 'react-router';
 import { useGlobal } from 'hooks/useGlobal';
 
@@ -45,22 +45,92 @@ export function titleForPath(pathname: string): string {
   return RULES.find((r) => r.match(pathname))?.title ?? 'Officer';
 }
 
-/** The current page title — shared (header ↔ tab), editable, per-tab (not persisted). */
-export const usePageTitle = () => useGlobal<string>('PAGE_TITLE', 'Officer');
+// ── The name you gave this tab ──
+// There is no tab identity in the DOM: `tabId` is a privileged extension API, and page scripts are
+// deliberately not allowed to know which tab they are in or that other tabs exist. We don't need one —
+// **sessionStorage is already the per-tab store.** It is separate per tab, survives a refresh and
+// in-place navigation, and is discarded when the tab closes, which is exactly the lifetime of a tab
+// name. localStorage would be wrong in the obvious way: every tab would share one name.
+
+const TAB_LABEL_KEY = 'OFFICER_TAB_LABEL';
+
+/** Storage can throw outright (private mode, storage disabled). A tab name is not worth a crash. */
+function readTabLabel(): string | null {
+  try {
+    return sessionStorage.getItem(TAB_LABEL_KEY);
+  } catch {
+    return null;
+  }
+}
+
+function writeTabLabel(label: string | null): void {
+  try {
+    if (label) sessionStorage.setItem(TAB_LABEL_KEY, label);
+    else sessionStorage.removeItem(TAB_LABEL_KEY);
+  } catch {
+    /* the name just doesn't persist */
+  }
+}
 
 /**
- * Mount once in the dashboard layout: reset the title to the route default on navigation, and mirror
- * whatever the title is into the browser tab. Editing the title in the header just sets this value,
- * so the tab updates live; navigating away resets it (no persistence, by design).
+ * Duplicating a tab **clones its sessionStorage**, so the copy would open wearing the original's name —
+ * two tabs called "Platform Arch", which is precisely what naming one was meant to prevent. Same for a
+ * tab opened by `window.open` from inside the app.
+ *
+ * A duplicate is a fresh navigation and a refresh is not, so `navigation.type` separates them: only a
+ * `navigate` arriving with a name it did not earn is a clone. A brand-new tab is `navigate` too, but has
+ * nothing stored, so it is untouched.
+ *
+ * It fails soft on purpose. If the timing entry is missing, or a browser labels duplication some other
+ * way, the copy simply keeps the name — redundant, not wrong.
+ */
+function dropInheritedTabLabel(): void {
+  try {
+    const [nav] = performance.getEntriesByType('navigation') as PerformanceNavigationTiming[];
+    if (nav?.type === 'navigate' && readTabLabel()) writeTabLabel(null);
+  } catch {
+    /* leave it alone */
+  }
+}
+
+// Once per document, before React reads the stored name.
+dropInheritedTabLabel();
+
+/**
+ * The title shown in the header and in the browser tab, plus the setter behind the header's edit.
+ *
+ * A name you type is a property of the **tab**, not of the page, so it outlives navigation as well as a
+ * refresh: you named this window to find it again among a dozen others, and wiping it because you opened
+ * a different screen would defeat the point. Clear the field to hand the tab back to the route's own
+ * name — that is the only way out, and there is no third state to get stuck in.
+ */
+export function usePageTitle() {
+  const { pathname } = useLocation();
+  const [label, setLabel] = useGlobal<string | null>('TAB_LABEL', readTabLabel);
+
+  // The React Query copy is what re-renders every consumer; sessionStorage is what survives the reload.
+  const rename = useCallback(
+    (next: string) => {
+      const trimmed = next.trim() || null;
+      writeTabLabel(trimmed);
+      setLabel(trimmed);
+    },
+    [setLabel],
+  );
+
+  return [label ?? titleForPath(pathname), rename] as const;
+}
+
+/**
+ * Mount once in the dashboard layout: mirror the title into the browser tab.
+ *
+ * There used to be a second effect resetting the title to the route default on every navigation, which
+ * is what made a typed name last only until you clicked something. The route default is derived now
+ * rather than assigned, so navigation retitles the tab by itself when no name is set, and leaves it
+ * alone when one is.
  */
 export function usePageTitleSync(): void {
-  const { pathname } = useLocation();
-  const [title, setTitle] = usePageTitle();
-
-  // Route default — depends only on the path, so an in-place header edit is never clobbered.
-  useEffect(() => {
-    setTitle(titleForPath(pathname));
-  }, [pathname]);
+  const [title] = usePageTitle();
 
   useEffect(() => {
     document.title = title || 'Officer';