From 374275eeb691006fa8f422d6267aa694ab38a992 Mon Sep 17 00:00:00 2001
From: Adam <2363879+adamdotdevin@users.noreply.github.com>
Date: Wed, 7 Jan 2026 08:41:16 -0600
Subject: feat(app): chunk message loading, lazy load diffs

---
 packages/app/src/utils/perf.ts | 135 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 packages/app/src/utils/perf.ts

(limited to 'packages/app/src/utils/perf.ts')

diff --git a/packages/app/src/utils/perf.ts b/packages/app/src/utils/perf.ts
new file mode 100644
index 000000000..0ecbc33ff
--- /dev/null
+++ b/packages/app/src/utils/perf.ts
@@ -0,0 +1,135 @@
+type Nav = {
+  id: string
+  dir?: string
+  from?: string
+  to: string
+  trigger?: string
+  start: number
+  marks: Record<string, number>
+  logged: boolean
+  timer?: ReturnType<typeof setTimeout>
+}
+
+const dev = import.meta.env.DEV
+
+const key = (dir: string | undefined, to: string) => `${dir ?? ""}:${to}`
+
+const now = () => performance.now()
+
+const uid = () => crypto.randomUUID?.() ?? Math.random().toString(16).slice(2)
+
+const navs = new Map<string, Nav>()
+const pending = new Map<string, string>()
+const active = new Map<string, string>()
+
+const required = [
+  "session:params",
+  "session:data-ready",
+  "session:first-turn-mounted",
+  "storage:prompt-ready",
+  "storage:terminal-ready",
+  "storage:file-view-ready",
+]
+
+function flush(id: string, reason: "complete" | "timeout") {
+  if (!dev) return
+  const nav = navs.get(id)
+  if (!nav) return
+  if (nav.logged) return
+
+  nav.logged = true
+  if (nav.timer) clearTimeout(nav.timer)
+
+  const baseName = nav.marks["navigate:start"] !== undefined ? "navigate:start" : "session:params"
+  const base = nav.marks[baseName] ?? nav.start
+
+  const ms = Object.fromEntries(
+    Object.entries(nav.marks)
+      .slice()
+      .sort(([a], [b]) => a.localeCompare(b))
+      .map(([name, t]) => [name, Math.round((t - base) * 100) / 100]),
+  )
+
+  console.log(
+    "perf.session-nav " +
+      JSON.stringify({
+        type: "perf.session-nav.v0",
+        id: nav.id,
+        dir: nav.dir,
+        from: nav.from,
+        to: nav.to,
+        trigger: nav.trigger,
+        base: baseName,
+        reason,
+        ms,
+      }),
+  )
+
+  navs.delete(id)
+}
+
+function maybeFlush(id: string) {
+  if (!dev) return
+  const nav = navs.get(id)
+  if (!nav) return
+  if (nav.logged) return
+  if (!required.every((name) => nav.marks[name] !== undefined)) return
+  flush(id, "complete")
+}
+
+function ensure(id: string, data: Omit<Nav, "marks" | "logged" | "timer">) {
+  const existing = navs.get(id)
+  if (existing) return existing
+
+  const nav: Nav = {
+    ...data,
+    marks: {},
+    logged: false,
+  }
+  nav.timer = setTimeout(() => flush(id, "timeout"), 5000)
+  navs.set(id, nav)
+  return nav
+}
+
+export function navStart(input: { dir?: string; from?: string; to: string; trigger?: string }) {
+  if (!dev) return
+
+  const id = uid()
+  const start = now()
+  const nav = ensure(id, { ...input, id, start })
+  nav.marks["navigate:start"] = start
+
+  pending.set(key(input.dir, input.to), id)
+  return id
+}
+
+export function navParams(input: { dir?: string; from?: string; to: string }) {
+  if (!dev) return
+
+  const k = key(input.dir, input.to)
+  const pendingId = pending.get(k)
+  if (pendingId) pending.delete(k)
+  const id = pendingId ?? uid()
+
+  const start = now()
+  const nav = ensure(id, { ...input, id, start, trigger: pendingId ? "key" : "route" })
+  nav.marks["session:params"] = start
+
+  active.set(k, id)
+  maybeFlush(id)
+  return id
+}
+
+export function navMark(input: { dir?: string; to: string; name: string }) {
+  if (!dev) return
+
+  const id = active.get(key(input.dir, input.to))
+  if (!id) return
+
+  const nav = navs.get(id)
+  if (!nav) return
+  if (nav.marks[input.name] !== undefined) return
+
+  nav.marks[input.name] = now()
+  maybeFlush(id)
+}
-- 
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