feat(sdk): Add granular presigned URL upload methods to StorageModule

[yash-pouranik]

Description:

Problem:
Previously, the StorageModule.upload method handled all three steps (requesting a signed URL, uploading the file, and confirming the upload) internally. This prevented developers from using a secure client-side direct-upload flow, as the secret key (sk) is required to generate the upload URL and confirm it, but cannot be exposed on the frontend. If developers uploaded files via their own backend using the SDK, the file had to travel through their backend to urBackend, doubling bandwidth and latency.

Solution:
This PR breaks down the file upload process into granular methods that allow developers to build a secure "Presigned URL" flow:

1. requestUploadUrl(filename, contentType, size): Exposed for the Developer's Backend (with sk) to generate a temporary, direct-to-cloud signed URL.
2. StorageModule.uploadToPresignedUrl(file, signedUrl, [contentType]): Added as a static helper method for the Frontend. It securely pushes the file (Blob/File/Buffer) straight to the cloud using the signed URL obtained from the backend.
3. confirmUpload(filePath, size): Exposed for the Developer's Backend to finalize the upload and update quota usage.

The original upload method remains unchanged and backwards-compatible (it now internally calls these new methods).

Usage Example:

Developer's Backend (Node.js):

app.post('/api/get-upload-link', async (req, res) => {
    // Requires sk
    const link = await urbackend.storage.requestUploadUrl("image.png", "image/png", 500000);
    res.json(link);
});

React Frontend:

import { StorageModule } from '@urbackend/sdk';

// Get link from backend
const { signedUrl, filePath } = await fetch('/api/get-upload-link').then(r => r.json());

// Upload directly to urBackend storage
await StorageModule.uploadToPresignedUrl(file, signedUrl);

// Notify backend to confirm...

Testing:

• Existing SDK tests pass successfully.
• Added comprehensive JSDoc comments for the new methods.

Summary by CodeRabbit

• New Features
  • Added presigned upload workflows for requesting upload URLs and confirming completed uploads.
  • Added direct uploads to presigned URLs using File, Blob, or Buffer data.
  • Added automatic content-type detection and improved upload failure handling.
• Improvements
  • Existing uploads now use the reusable presigned upload workflow for more consistent behavior.

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Project	Deployment	Actions	Updated (UTC)
ur-backend-web-dashboard	Ready	Preview	Aug 24, 2026 8:57am

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
urbackend	Skipped		Aug 24, 2026 8:57am

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⚙️ Run configuration

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📥 Commits

Reviewing files that changed from the base of the PR and between dd77d89 and 5e2bdd8.

📒 Files selected for processing (2)

• mintlify/docs/sdk/storage.mdx
• sdks/urbackend-sdk/src/modules/storage.ts

📝 Walkthrough

Walkthrough

StorageModule now exposes reusable upload URL request and confirmation methods. It also adds direct presigned URL uploads for File, Blob, and Buffer inputs with content-type detection and failure handling.

Changes

Presigned upload workflow

Layer / File(s)	Summary
Upload request and confirmation sdks/urbackend-sdk/src/modules/storage.ts	upload uses the public requestUploadUrl and confirmUpload methods. The request method returns the signed URL, file path, and optional token.
Direct presigned URL upload sdks/urbackend-sdk/src/modules/storage.ts	uploadToPresignedUrl accepts File, Blob, or Buffer data, sets the content type, performs a PUT request, and throws for unsupported inputs or failed responses.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🔵 Low · up to dd77d

Buffer uploads can fail in environments where Blob is unavailable because both upload methods access Blob before checking the Buffer path. The PR is mergeable with explicit owner follow-up to guard that check.

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant StorageModule
  participant UploadAPI
  participant PresignedStorage
  Client->>StorageModule: upload(filename, file)
  StorageModule->>UploadAPI: requestUploadUrl(filename, contentType, size)
  UploadAPI-->>StorageModule: signedUrl and filePath
  StorageModule->>PresignedStorage: PUT file to signedUrl
  PresignedStorage-->>StorageModule: upload response
  StorageModule->>UploadAPI: confirmUpload(filePath, size)
  UploadAPI-->>Client: UploadResponse

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Suggested reviewers: nitin-kumar-yadav1307

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding granular presigned URL upload methods to StorageModule.
Docstring Coverage	✅ Passed	Docstring check was indeterminate for this PR — some files could not be analyzed in time. Not blocking.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feature/sdk-upload-presigned

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Actionable comments posted: 1

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Inline comments:
In `@sdks/urbackend-sdk/src/modules/storage.ts`:
- Around line 166-180: Guard the Blob instanceof checks in both upload and
uploadToPresignedUrl with a typeof Blob !== "undefined" condition so
environments without Blob can reach the existing Buffer handling. Keep the
current File, Blob, Buffer, and unsupported-type behavior otherwise unchanged.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📥 Commits

Reviewing files that changed from the base of the PR and between 26d59d5 and dd77d89.

📒 Files selected for processing (1)

• sdks/urbackend-sdk/src/modules/storage.ts

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