diff --git a/apps/desktop/electron/main.ts b/apps/desktop/electron/main.ts
index 646eefc6eb2d..e0dd2c4fb549 100644
--- a/apps/desktop/electron/main.ts
+++ b/apps/desktop/electron/main.ts
@@ -5212,6 +5212,50 @@ function getOauthSession() {
   return oauthSession
 }
 
+// Cold-start cookie-jar warm-up. A `persist:` partition materialized via
+// session.fromPartition() loads its on-disk cookie store LAZILY: the very first
+// cookies.get() on a fresh cold start can resolve BEFORE the jar has finished
+// hydrating from disk and return an empty array — even though the user is
+// signed in. That false-negative used to make hasLiveOauthSession() report
+// "not signed in", which on the initial boot path (startHermes → the renderer's
+// single-shot boot() with no retry) surfaced as the "Hermes couldn't start"
+// OAuth overlay that vanishes the instant the user clicks Retry.
+//
+// We force the store to hydrate once, up front: flushStorageData() then a
+// throwaway cookies.get(). The promise is memoized so every caller awaits the
+// same single warm-up. Best-effort — any error resolves so we fall back to the
+// live read (which then does its own bounded re-check).
+let oauthCookieWarmup: Promise<void> | null = null
+
+function warmOauthCookieStore() {
+  if (oauthCookieWarmup) {
+    return oauthCookieWarmup
+  }
+
+  oauthCookieWarmup = (async () => {
+    const sess = getOauthSession()
+
+    if (!sess) {
+      // App not ready yet — don't memoize a no-op; let a later call retry.
+      oauthCookieWarmup = null
+
+      return
+    }
+
+    try {
+      // flushStorageData() forces Chromium to reconcile the in-memory cookie
+      // monster with the on-disk SQLite store; the subsequent get() then reads
+      // a populated jar rather than racing the lazy first-access load.
+      sess.flushStorageData?.()
+      await sess.cookies.get({})
+    } catch {
+      // Best effort; the real read below re-checks with bounded retries.
+    }
+  })()
+
+  return oauthCookieWarmup
+}
+
 // Bare + prefixed variants of the session cookies live in
 // connection-config.ts (cookiesHaveSession / cookiesHaveLiveSession). See
 // that module for details.
@@ -5258,19 +5302,45 @@ async function hasLiveOauthSession(baseUrl) {
 
   const parsed = new URL(baseUrl)
 
-  try {
-    const cookies = await sess.cookies.get({ url: baseUrl })
-
-    return cookiesHaveLiveSession(cookies)
-  } catch {
+  const readLive = async () => {
     try {
-      const cookies = await sess.cookies.get({ domain: parsed.hostname })
+      const cookies = await sess.cookies.get({ url: baseUrl })
 
       return cookiesHaveLiveSession(cookies)
     } catch {
-      return false
+      try {
+        const cookies = await sess.cookies.get({ domain: parsed.hostname })
+
+        return cookiesHaveLiveSession(cookies)
+      } catch {
+        return false
+      }
     }
   }
+
+  // First read against the (possibly still-hydrating) jar.
+  if (await readLive()) {
+    return true
+  }
+
+  // Cold-start false-negative guard. A `persist:` partition's cookie store
+  // loads lazily, so the FIRST read on a fresh boot can come back empty even
+  // for a signed-in user — the exact race that produced the transient "Hermes
+  // couldn't start / not signed in" overlay that Retry always cleared. Before
+  // trusting a negative, force the store to hydrate and re-read a couple of
+  // times with a short backoff. A genuinely signed-out user still resolves
+  // false quickly (≤ ~180ms); a signed-in user racing the load now wins.
+  await warmOauthCookieStore()
+
+  for (const delayMs of [30, 60, 90]) {
+    if (await readLive()) {
+      return true
+    }
+
+    await new Promise(resolve => setTimeout(resolve, delayMs))
+  }
+
+  return readLive()
 }
 
 async function clearOauthSession(baseUrl) {