diff --git a/apps/desktop/electron/connection-config.test.ts b/apps/desktop/electron/connection-config.test.ts
index 4361678cb8fe..e8a4ca8e3803 100644
--- a/apps/desktop/electron/connection-config.test.ts
+++ b/apps/desktop/electron/connection-config.test.ts
@@ -35,6 +35,7 @@ import {
   profileHasRemoteConnection,
   profileRemoteOverride,
   profileSshOverride,
+  profileUsesPrimaryBackend,
   resolveAuthMode,
   resolveTestWsUrl,
   RT_COOKIE_VARIANTS,
@@ -187,6 +188,44 @@ test('saved SSH drafts are inactive and explicit overrides take precedence', ()
   assert.equal(profileHasRemoteConnection(config, 'coder'), true)
 })
 
+// --- profileUsesPrimaryBackend ---
+
+test('profileUsesPrimaryBackend keeps primary and empty scopes on the window backend', () => {
+  assert.equal(profileUsesPrimaryBackend('default', { primaryProfile: 'default' }), true)
+  assert.equal(profileUsesPrimaryBackend(' coder ', { primaryProfile: 'coder' }), true)
+  assert.equal(profileUsesPrimaryBackend('', { primaryProfile: 'default' }), true)
+})
+
+test('profileUsesPrimaryBackend shares one app-global remote across profiles', () => {
+  assert.equal(
+    profileUsesPrimaryBackend('coder', {
+      primaryProfile: 'default',
+      globalRemote: true,
+      profileRemoteOverride: false
+    }),
+    true
+  )
+})
+
+test('profileUsesPrimaryBackend preserves profile overrides and local profile backends', () => {
+  assert.equal(
+    profileUsesPrimaryBackend('coder', {
+      primaryProfile: 'default',
+      globalRemote: true,
+      profileRemoteOverride: true
+    }),
+    false
+  )
+  assert.equal(
+    profileUsesPrimaryBackend('coder', {
+      primaryProfile: 'default',
+      globalRemote: false,
+      profileRemoteOverride: false
+    }),
+    false
+  )
+})
+
 // --- pathWithGlobalRemoteProfile ---
 
 test('pathWithGlobalRemoteProfile appends profile in global remote mode', () => {
diff --git a/apps/desktop/electron/connection-config.ts b/apps/desktop/electron/connection-config.ts
index f7b1ac2e0d42..f5cd7763d7d5 100644
--- a/apps/desktop/electron/connection-config.ts
+++ b/apps/desktop/electron/connection-config.ts
@@ -350,6 +350,24 @@ function profileRemoteOverride(config, profile) {
   return { url, authMode: normAuthMode(entry.authMode), token: entry.token }
 }
 
+/**
+ * Decide whether a profile should reuse the primary backend connection.
+ *
+ * The primary profile always owns the window backend. In app-global remote
+ * mode, that same backend serves every profile through request-level profile
+ * scoping, unless a profile has its own remote connection override.
+ */
+function profileUsesPrimaryBackend(profile, opts: any = {}) {
+  const scopedProfile = connectionScopeKey(profile)
+  const primaryProfile = connectionScopeKey(opts.primaryProfile) || 'default'
+
+  if (!scopedProfile || scopedProfile === primaryProfile) {
+    return true
+  }
+
+  return Boolean(opts.globalRemote) && !opts.profileRemoteOverride
+}
+
 /**
  * In global-remote mode one backend serves every Desktop profile, so REST calls
  * that are scoped by renderer-side `request.profile` must carry that scope as a
@@ -505,6 +523,7 @@ export {
   profileHasRemoteConnection,
   profileRemoteOverride,
   profileSshOverride,
+  profileUsesPrimaryBackend,
   resolveAuthMode,
   resolveTestWsUrl,
   RT_COOKIE_VARIANTS,
diff --git a/apps/desktop/electron/main.ts b/apps/desktop/electron/main.ts
index d4cb1ccb5f5d..ed0296cf362b 100644
--- a/apps/desktop/electron/main.ts
+++ b/apps/desktop/electron/main.ts
@@ -63,6 +63,7 @@ import {
   profileHasRemoteConnection,
   profileRemoteOverride,
   profileSshOverride,
+  profileUsesPrimaryBackend,
   resolveAuthMode,
   resolveTestWsUrl,
   savedProfileSsh,
@@ -7727,17 +7728,35 @@ function primaryProfileKey() {
   return readActiveDesktopProfile() || 'default'
 }
 
-// Resolve a backend connection for the given profile. Routes the primary
-// profile to startHermes() (the window backend: boot UI, bootstrap, remote
-// mode), and any OTHER profile to a lazily-spawned pool backend. An empty /
-// unknown profile resolves to the primary, so all legacy callers are unchanged.
+// Resolve a backend connection for the given profile. The primary profile uses
+// startHermes() (the window backend: boot UI, bootstrap, remote mode). Profiles
+// inheriting an app-global remote share that same connection because the remote
+// backend scopes their requests by profile. Other profiles use lazily-spawned
+// pool backends. An empty / unknown profile resolves to the primary.
 async function ensureBackend(profile) {
-  const key = profile && String(profile).trim() ? String(profile).trim() : primaryProfileKey()
+  const primaryProfile = primaryProfileKey()
+  const key = profile && String(profile).trim() ? String(profile).trim() : primaryProfile
 
-  if (key === primaryProfileKey()) {
+  if (key === primaryProfile) {
     return startHermes()
   }
 
+  if (
+    globalRemoteActive() &&
+    profileUsesPrimaryBackend(key, {
+      primaryProfile,
+      globalRemote: true,
+      profileRemoteOverride: profileHasRemoteOverride(key)
+    })
+  ) {
+    const connection = await startHermes()
+
+    // Non-primary global-remote profiles still need their scope on the
+    // descriptor so renderer-side WebSocket, filesystem, and cache routing use
+    // the selected profile while sharing the one underlying backend.
+    return { ...connection, profile: key }
+  }
+
   const existing = backendPool.get(key)
 
   if (existing) {