@nuxthub/core race: blob shim overwritten

[onmax]

Title: @nuxthub/core race condition: concurrent Nuxt runs overwrite generated @nuxthub/blob shim (wrong driver / can corrupt file)

Summary

When two Nuxt commands run concurrently in the same project (e.g. nuxt typecheck and nuxt build), @nuxthub/core writes a generated physical package to node_modules/@nuxthub/blob/ from both processes. Because the path is shared, concurrent runs race and the contents are non-deterministic.

In practice this can cause:

• Wrong driver: after a Cloudflare build, the generated shim ends up as the fs driver variant.
• Corruption: the generated blob.mjs can end up partially written / interleaved, causing bundler parse errors.

Why this is a bug

• node_modules/@nuxthub/blob/blob.mjs is written during module setup and is shared across processes.
• Concurrent writes are not atomic, so output depends on timing and can be corrupted.
• nuxt typecheck should not mutate shared runtime shims in node_modules/.

Code pointer

The physical shim is generated during module setup:

• src/blob/setup.ts (setupBlob()): writes node_modules/@nuxthub/blob/blob.mjs, blob.d.ts, package.json.

Expected

After NITRO_PRESET=cloudflare-module nuxt build, the generated blob shim should be stable and match Cloudflare (R2) configuration (or at least not be overwritten by a concurrent nuxt typecheck).

Actual

Within a few attempts, blob.mjs ends up as the fs driver variant after build:

import { createBlobStorage } from "@nuxthub/core/blob";
import { createDriver } from "@nuxthub/core/blob/drivers/fs";

export { ensureBlob } from "@nuxthub/core/blob";
export const blob = createBlobStorage(createDriver({"dir":"/path/to/.data/blob"}));

Environment

• macOS
• Node v25.6.0
• pnpm 10.29.2
• nuxt 4.3.1
• nitro 2.13.1
• @nuxthub/core 0.10.6

Fix direction

• Avoid generating shims into the project node_modules/ during module setup (especially for typecheck/dev).
• If a physical package is needed for external bundlers/workflows, generate it only during build hooks.
• Make writes atomic (tmp + rename) to avoid partial/corrupted files.

Repro repo

• Bug: https://github.com/onmax/repros/tree/main/nuxthub-830
• Fix (pnpm patch): https://github.com/onmax/repros/tree/main/nuxthub-830-fix

StackBlitz (auto install + run):

• Bug: https://stackblitz.com/github/onmax/repros/tree/main/nuxthub-830?startScript=verify
• Fix: https://stackblitz.com/github/onmax/repros/tree/main/nuxthub-830-fix?startScript=verify

[onmax]

Fix: #831

[atinux]

Actually this could be the same issue by running two concurrent nuxt commands writing in the .nuxt directory. If using multiple agents, best might be to use worktree there