fix: finalize gpt-5.4.3 review follow-ups

- remove redundant fallback seed mutex in storage path
- clarify fallback policy scope for gpt-5.4-pro docs
- rename storage fallback test to match serialized execution

Author: ndycode

docs/getting-started.md

@@ -207,7 +207,7 @@ Safe mode effects:
 | Model | Variants | Notes |
 |-------|----------|-------|
 | `gpt-5.4` | none, low, medium, high, xhigh | Latest GPT-5.4 (1,000,000 context) |
-| `gpt-5.4-pro` | low, medium, high, xhigh | Optional manual model for deeper reasoning; fallback default is `gpt-5.4-pro -> gpt-5.4` (1,000,000 context) |
+| `gpt-5.4-pro` | low, medium, high, xhigh | Optional manual model for deeper reasoning; when `unsupportedCodexPolicy=fallback`, fallback includes `gpt-5.4-pro -> gpt-5.4` (1,000,000 context) |
 | `gpt-5-codex` | low, medium, high | Canonical Codex for code generation |
 | `gpt-5.3-codex-spark` | low, medium, high, xhigh | Optional manual model; entitlement-gated by account/workspace |
 | `gpt-5.1-codex-max` | low, medium, high, xhigh | Maximum context |

lib/storage.ts

@@ -107,7 +107,6 @@ export function formatStorageErrorHint(error: unknown, path: string): string {
 }
 
 let storageMutex: Promise<void> = Promise.resolve();
-let fallbackSeedMutex: Promise<void> = Promise.resolve();
 
 function withStorageLock<T>(fn: () => Promise<T>): Promise<T> {
   const previousMutex = storageMutex;
@@ -118,15 +117,6 @@ function withStorageLock<T>(fn: () => Promise<T>): Promise<T> {
   return previousMutex.then(fn).finally(() => releaseLock());
 }
 
-function withFallbackSeedLock<T>(fn: () => Promise<T>): Promise<T> {
-  const previousMutex = fallbackSeedMutex;
-  let releaseLock: () => void;
-  fallbackSeedMutex = new Promise<void>((resolve) => {
-    releaseLock = resolve;
-  });
-  return previousMutex.then(fn).finally(() => releaseLock());
-}
-
 const WINDOWS_RENAME_RETRY_ATTEMPTS = 5;
 const WINDOWS_RENAME_RETRY_BASE_DELAY_MS = 10;
 const PRE_IMPORT_BACKUP_WRITE_TIMEOUT_MS = 3_000;
@@ -770,36 +760,34 @@ async function loadAccountsInternal(
       if (!globalFallback) return null;
 
       if (persistMigration) {
-        await withFallbackSeedLock(async () => {
-          const seedPath = getStoragePath();
-          try {
-            await fs.access(seedPath);
-            return;
-          } catch (accessError) {
-            const accessCode = (accessError as NodeJS.ErrnoException).code;
-            if (accessCode !== "ENOENT") {
-              log.warn("Failed to inspect project seed path before fallback seeding", {
-                path: seedPath,
-                error: String(accessError),
-              });
-              return;
-            }
-            // File is missing; proceed with seed write.
-          }
-
-          try {
-            await persistMigration(globalFallback);
-            log.info("Seeded project account storage from global fallback", {
-              path: seedPath,
-              accounts: globalFallback.accounts.length,
-            });
-          } catch (persistError) {
-            log.warn("Failed to seed project storage from global fallback", {
+        const seedPath = getStoragePath();
+        try {
+          await fs.access(seedPath);
+          return globalFallback;
+        } catch (accessError) {
+          const accessCode = (accessError as NodeJS.ErrnoException).code;
+          if (accessCode !== "ENOENT") {
+            log.warn("Failed to inspect project seed path before fallback seeding", {
               path: seedPath,
-              error: String(persistError),
+              error: String(accessError),
             });
+            return globalFallback;
           }
-        });
+          // File is missing; proceed with seed write.
+        }
+
+        try {
+          await persistMigration(globalFallback);
+          log.info("Seeded project account storage from global fallback", {
+            path: seedPath,
+            accounts: globalFallback.accounts.length,
+          });
+        } catch (persistError) {
+          log.warn("Failed to seed project storage from global fallback", {
+            path: seedPath,
+            error: String(persistError),
+          });
+        }
       }
 
       return globalFallback;

test/storage.test.ts

@@ -1825,7 +1825,7 @@ describe("storage", () => {
       expect(seeded.accounts?.[0]?.accountId).toBe("global-account");
     });
 
-    it("seeds project storage only once for concurrent global-fallback loads", async () => {
+    it("seeds project storage only once across serialized global-fallback loads", async () => {
       const fakeHome = join(testWorkDir, "home-fallback-concurrent");
       const projectDir = join(testWorkDir, "project-fallback-concurrent");
       const projectGitDir = join(projectDir, ".git");