Cache browser history by identity and snapshot omnibox entries

- Use WeakMap to cache prepared browser history entries by identity, so
  re-parsing is skipped for the same snapshot
- Change omnibox to read a history snapshot at menu open (via getState)
  instead of subscribing to live updates, preventing background navigations
  from reshuffling results mid-keystroke
- Support fully-qualified URL prefix matching (e.g., `https://github.com`)
  to preserve address-bar behavior
- Fix percentile calculation in performance tests (nearest-rank method)

src/renderer/src/components/tab-bar/TabBarCreateEntry.history.test.tsx

@@ -41,7 +41,7 @@ vi.mock('@/store', () => ({
         browserDefaultSearchEngine: 'google',
         getKnownWorktreeById: () => ({ path: '/tmp/wt' })
       }),
-    { getState: () => ({}) }
+    { getState: () => ({ browserUrlHistory: historyStoreMock.entries }) }
   )
 }))
 vi.mock('react', async () => {

src/renderer/src/components/tab-bar/use-omnibox-browser-history.ts

@@ -85,9 +85,14 @@ export function useOmniboxBrowserHistory({
   query: string
   tabResults: readonly OpenTabSearchResult[]
 }): readonly BrowserHistoryOmniboxRow[] {
-  // Why null while disabled: the tab bar is mounted for every workspace, and
-  // this array is replaced on every committed navigation in any browser tab.
-  const history = useAppStore((store) => (enabled ? store.browserUrlHistory : null))
+  // Why read once: the tab bar is mounted for every workspace, and this array
+  // is replaced on every committed navigation in any browser tab. History is
+  // intentionally a per-open snapshot so background navigations cannot churn
+  // the omnibox or reshuffle a selection under the user's fingers.
+  const history = useMemo(
+    () => (enabled ? useAppStore.getState().browserUrlHistory : null),
+    [enabled]
+  )
   const prepared = useMemo(
     () => (history ? prepareBrowserHistoryEntries(history) : null),
     // oxlint-disable-next-line react-hooks/exhaustive-deps -- Snapshot per menu open; a background navigation must not reshuffle rows mid-keystroke.

src/renderer/src/lib/browser-history-match.performance.test.ts

@@ -26,7 +26,8 @@ const WORST_QUERY = 'observability rollout'
 
 function percentile95(samples: number[]): number {
   const sorted = [...samples].sort((a, b) => a - b)
-  return sorted[Math.min(sorted.length - 1, Math.floor(sorted.length * 0.95))]
+  // Nearest-rank p95: ceil(n*0.95)-1, so 20 samples pick index 18 rather than the max.
+  return sorted[Math.min(sorted.length - 1, Math.ceil(sorted.length * 0.95) - 1)]
 }
 
 describe('browser history match performance budget', () => {
@@ -41,7 +42,9 @@ describe('browser history match performance budget', () => {
     const samples: number[] = []
     for (let run = 0; run < 20; run += 1) {
       const start = performance.now()
-      prepareBrowserHistoryEntries(entries)
+      // Use a fresh array identity so this measures preparation rather than
+      // the identity cache used by live address bars and omniboxes.
+      prepareBrowserHistoryEntries(entries.slice())
       samples.push(performance.now() - start)
     }
     expect(percentile95(samples)).toBeLessThan(prepareP95Ms)

src/renderer/src/lib/browser-history-match.test.ts

@@ -56,6 +56,12 @@ describe('browser history match', () => {
     ])
   })
 
+  it('keeps fully-qualified URL prefixes in the top tier', () => {
+    expect(match([entry({ url: 'https://github.com/acme' })], 'https://github.com')).toEqual([
+      { tier: 'host-prefix', url: 'https://github.com/acme' }
+    ])
+  })
+
   it('leaves a subdomain match in host-substring rather than host-prefix', () => {
     expect(match([entry({ url: 'https://docs.github.com/actions' })], 'git')).toEqual([
       { tier: 'host-substring', url: 'https://docs.github.com/actions' }
@@ -131,6 +137,13 @@ describe('browser history match', () => {
     expect(matchBrowserHistory({ prepared, query: 'git', limit: 0, now: NOW })).toBe(missA)
   })
 
+  it('reuses preparation for the same immutable history snapshot', () => {
+    const first = prepareBrowserHistoryEntries(GIT_CORPUS)
+
+    expect(prepareBrowserHistoryEntries(GIT_CORPUS)).toBe(first)
+    expect(prepareBrowserHistoryEntries([...GIT_CORPUS])).not.toBe(first)
+  })
+
   it('survives an unparseable url by falling back to url and title matching', () => {
     const broken = entry({ url: 'not a url at all', title: 'Broken' })
 

src/renderer/src/lib/browser-history-match.ts

@@ -34,6 +34,10 @@ export type BrowserHistoryMatch = {
 }
 
 const NO_MATCHES: readonly BrowserHistoryMatch[] = []
+const preparedHistoryCache = new WeakMap<
+  readonly BrowserHistoryEntry[],
+  readonly PreparedBrowserHistoryEntry[]
+>()
 
 function historyHost(url: string): string {
   try {
@@ -53,13 +57,19 @@ export function formatBrowserHistoryUrl(url: string): string {
 export function prepareBrowserHistoryEntries(
   entries: readonly BrowserHistoryEntry[]
 ): readonly PreparedBrowserHistoryEntry[] {
-  return entries.map((entry) => ({
+  const cached = preparedHistoryCache.get(entries)
+  if (cached) {
+    return cached
+  }
+  const prepared = entries.map((entry) => ({
     entry,
     lowerUrl: entry.url.toLowerCase(),
     lowerTitle: entry.title.toLowerCase(),
     lowerHost: historyHost(entry.url),
     frecencyBase: Math.min(entry.visitCount, MAX_VISIT_COUNT_BONUS)
   }))
+  preparedHistoryCache.set(entries, prepared)
+  return prepared
 }
 
 function matchTier(
@@ -69,7 +79,9 @@ function matchTier(
   // A workspace-doc entry's url is a filesystem path, so it has no host: a path
   // prefix is as deliberate as a host prefix and earns the same top tier.
   const prefixTarget = prepared.lowerHost === '' ? prepared.lowerUrl : prepared.lowerHost
-  if (prefixTarget.startsWith(lowerQuery)) {
+  // Preserve the address-bar's long-standing behavior for fully-qualified
+  // input (e.g. `https://github.com`), while still ranking bare hosts by host.
+  if (prefixTarget.startsWith(lowerQuery) || prepared.lowerUrl.startsWith(lowerQuery)) {
     return 'host-prefix'
   }
   if (prepared.lowerHost.includes(lowerQuery)) {