feat: Add Blob as a default endowment#4063
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naugtur
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Jul 13, 2026
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Blob global is a constructor for data views, it doesn't bring in any new powers that didn't already exist with fetch or typed ararys
Mrtenz
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Jul 13, 2026
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Release candidate for `164.0.0`. Including support for `Blob` in Snaps. <!-- CURSOR_SUMMARY --> --- > [!NOTE] > **Low Risk** > Version and changelog-only release; sandbox surface grows slightly via the Blob endowment already merged in prior PRs. > > **Overview** > Release cut for **164.0.0** that bumps the monorepo version and publishes **`@metamask/snaps-utils@12.4.0`** and **`@metamask/snaps-execution-environments@11.2.0`**. > > The highlighted user-facing change in these package notes is **`Blob` as a default Snap endowment** ([MetaMask#4063](MetaMask#4063)), so Snaps can use `Blob` without an extra permission. The execution-environments release also records a **`@metamask/superstruct`** bump to `^3.3.0` ([MetaMask#4062](MetaMask#4062)). > > No application logic appears in this diff—only version fields and changelog/compare-link updates. > > <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit 1a21ee3. Bugbot is set up for automated code reviews on this repo. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup> <!-- /CURSOR_SUMMARY -->
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Add
Blobas a default endowment forinstanceofchecks when usingfetch.https://consensyssoftware.atlassian.net/browse/WPC-1126
Note
Low Risk
Small expansion of the default sandbox API using the same hardened global pattern as other Web platform types; no auth or network policy changes.
Overview
Snaps now receive a hardened global
Blobby default, alongside existing fetch-related globals likeResponse.Blobis registered in the common endowment factory, included inDEFAULT_ENDOWMENTS, and covered by hardening and executor tests (includingfetch→res.blob()→instanceof Blob). Simulation endowment snapshots are updated to listBlob.Reviewed by Cursor Bugbot for commit 00347d2. Bugbot is set up for automated code reviews on this repo. Configure here.