RC: enable system-default real-home routing by default (flag ON)

Flip codexSystemDefaultRealHomeEnabled to default ON for this RC's staged
rollout (a user can still opt out by setting it false, which stays byte-identical
to managed-home behavior). This is the only intended behavior difference between
the RC branch and the individual PRs. Updates the two tests that assumed the
prior OFF default.

src/main/codex-accounts/runtime-home-service.test.ts

@@ -42,6 +42,9 @@ function createSettings(overrides: Partial<GlobalSettings> = {}): GlobalSettings
   const agentStatusHooksEnabled = overrides.agentStatusHooksEnabled ?? true
   const tabAutoGenerateTitle = overrides.tabAutoGenerateTitle ?? false
   return {
+    // Managed-home tests assert the mirror path; the RC defaults the real-home
+    // flag ON, so opt these managed cases out unless a test overrides it.
+    codexSystemDefaultRealHomeEnabled: overrides.codexSystemDefaultRealHomeEnabled ?? false,
     workspaceDir: testState.fakeHomeDir,
     nestWorkspaces: false,
     refreshLocalBaseRefOnWorktreeCreate: false,

src/main/codex/codex-real-home-flag.test.ts

@@ -18,10 +18,10 @@ afterEach(() => {
 })
 
 describe('isCodexSystemDefaultRealHomeEnabled', () => {
-  it('is OFF by default (undefined settings)', () => {
-    expect(isCodexSystemDefaultRealHomeEnabled(undefined)).toBe(false)
-    expect(isCodexSystemDefaultRealHomeEnabled(null)).toBe(false)
-    expect(isCodexSystemDefaultRealHomeEnabled({})).toBe(false)
+  it('is ON by default on this RC (undefined settings)', () => {
+    expect(isCodexSystemDefaultRealHomeEnabled(undefined)).toBe(true)
+    expect(isCodexSystemDefaultRealHomeEnabled(null)).toBe(true)
+    expect(isCodexSystemDefaultRealHomeEnabled({})).toBe(true)
   })
 
   it('honors the settings flag when set to true', () => {

src/main/codex/codex-real-home-flag.ts

@@ -5,8 +5,9 @@ import type { GlobalSettings } from '../../shared/types'
  * real ~/.codex instead of Orca's managed runtime home.
  *
  * Why a flag: this moves where user Codex state lives (auth, config, sessions,
- * hooks). It ships dark, default OFF, with NO settings UI, so flag-OFF stays
- * byte-identical to today's managed-home behavior. Managed (multi-account)
+ * hooks). It is ENABLED BY DEFAULT on this RC for the staged rollout; a user can
+ * still opt out by setting codexSystemDefaultRealHomeEnabled to false, which
+ * stays byte-identical to today's managed-home behavior. Managed (multi-account)
  * selections are unaffected either way.
  *
  * The env override exists only so isolated dev/CDP verification can exercise
@@ -21,7 +22,7 @@ export function isCodexSystemDefaultRealHomeEnabled(
   if (envOverride !== null) {
     return envOverride
   }
-  return settings?.codexSystemDefaultRealHomeEnabled === true
+  return settings?.codexSystemDefaultRealHomeEnabled !== false
 }
 
 function readCodexRealHomeEnvOverride(): boolean | null {