fix(blob): enforce maximumSizeInBytes client-side for multipart uploads

[matingathani]

Summary

Fixes #873 — maximumSizeInBytes was not enforced for multipart uploads.

uncontrolledMultipartUpload never checked maximumSizeInBytes. For bodies with a known size (Blob, File, Buffer), a client-side check is now done before the multipart upload begins, avoiding wasted API calls (create + upload parts) that would ultimately be rejected by the server.

Streams are skipped since their size is unknown upfront — enforcement is left to the server.

Also adds maximumSizeInBytes to CommonCreateBlobOptions so it's available to the multipart code path.

Test plan

• New test: multipart: true + maximumSizeInBytes throws before upload starts
• New test: stream body with maximumSizeInBytes does not throw client-side

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[changeset-bot]

🦋 Changeset detected

Latest commit: d91f40c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@vercel/blob	Patch
vercel-storage-integration-test-suite	Patch

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[Copilot]

Pull request overview

This PR fixes two @vercel/blob upload issues: (1) missing x-content-length for empty (0-byte) non-stream uploads, and (2) missing maximumSizeInBytes enforcement for multipart uploads, adding tests to cover both behaviors.

Changes:

• Always send x-content-length for non-stream bodies (including 0-byte Blobs) in requestApi.
• Enforce maximumSizeInBytes client-side before starting an uncontrolled multipart upload.
• Add/adjust Node tests to validate the new header behavior and multipart size enforcement.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/blob/src/api.ts	Ensures x-content-length is sent for all non-stream bodies, including empty bodies.
packages/blob/src/api.node.test.ts	Adds coverage for x-content-length behavior (0-byte Blob + non-empty Blob without progress).
packages/blob/src/multipart/uncontrolled.ts	Adds preflight maximumSizeInBytes enforcement before multipart upload creation.
packages/blob/src/helpers.ts	Adds maximumSizeInBytes to CommonCreateBlobOptions and documents intended behavior.
packages/blob/src/index.node.test.ts	Adds a test asserting multipart put() throws when exceeding maximumSizeInBytes.

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[matingathani]

Addressed Copilot's review comments in the follow-up commit (ee4224d): changed the options type to CommonCreateBlobOptions & WithUploadProgress to resolve the type mismatch, tightened the JSDoc to accurately reflect multipart-only enforcement, and fixed the empty-string edge case in the body length guard. All 105 tests still passing locally.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
vercel-storage-next-integration-test-suite	Ready	Preview	Apr 2, 2026 1:00pm

[vvo]

@matingathani Thanks. We just updated our Blob API to allow for empty files to be uploaded. I kept your addition as for making max size check locally on multipart uploads.

[matingathani]

Thanks for merging and for the context! Really glad the multipart size check was useful. I'd love to keep contributing to this repo , I am happy to pick up issues or dive into areas where help is needed. Looking forward to learning more about how the Blob API works under the hood.