[PerryLink]

Problem

createAssetFactory declares its input as Binary.Source, which is an ArrayBuffer or any ArrayBufferView. The view branch dereferenced .buffer before encoding:

} else if (ArrayBuffer.isView(src)) {
  src = prefix + Binary.toBase64(src.buffer)
}

An ArrayBufferView is a window onto a buffer: its bytes are byteOffset .. byteOffset + byteLength, not the whole backing store. Passing .buffer therefore encodes every byte the view was carved out of. A three-byte view into a six-byte buffer yields base64://AAABAgMA instead of base64://AQID; the same happens for DataView and for the mime type form of file().

Fix

Binary.toBase64 already handles a view correctly, so pass the view itself:

-        src = prefix + Binary.toBase64(src.buffer)
+        src = prefix + Binary.toBase64(src)

Relation to #431

This is the same fix as #431, which targets main. main is no longer where development happens: its install has been broken since 2026-10-07 on an unpublished dependency, and active work moved to v4. This PR is the v4 version of the change; #431 is superseded by it.

Tests

Adds packages/element/tests/index.spec.ts, covering string, Buffer, ArrayBuffer, a Uint8Array view with a non-zero byteOffset, a DataView, and the mime type variant — the same cases as #431.

Red before the fix (reproduced twice, identical):

✖ Uint8Array view
  expected 'base64://AAABAgMA' to equal 'base64://AQID'
✖ DataView
  expected 'base64://AAABAgMA' to equal 'base64://AQID'
✖ mime type
  expected 'data:image/png;base64,AAABAgMA' to equal 'data:image/png;base64,AQID'
ℹ tests 6
ℹ pass 3
ℹ fail 3

Green after the fix:

✔ string source
✔ Buffer source
✔ ArrayBuffer source
✔ Uint8Array view
✔ DataView
✔ mime type
ℹ tests 6
ℹ pass 6
ℹ fail 0

Both element test files together: ℹ tests 19 / pass 19 / fail 0.

• pnpm exec yakumo build element — exit 0
• pnpm lint — exit 0
• pnpm exec eslint packages/element/tests/index.spec.ts --no-ignore — exit 0 (the repo's .eslintignore excludes tests, so this is informational)

Because the v4 test script still does not forward the tsx loader to the node --test child, the tests above were run directly with node --import tsx --test packages/element/tests/*.spec.ts.

CI

lint and build pass. test (20) / test (22) currently fail on this PR, but they fail at load time, before any assertion runs, because the base branch's test script still drops the loader: the new file hits ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX (namespace in src), segment.spec.ts hits ERR_UNSUPPORTED_DIR_IMPORT, and protocol.spec.ts hits ERR_MODULE_NOT_FOUND for @satorijs/element/lib. That is the pre-existing v4 test failure fixed separately by #438 (which makes both test jobs green); once #438 is on v4, this PR's test jobs will exercise the new cases. publish is skipped on pull requests; the red publish job on v4's head is unrelated to this change.

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Additional details and impacted files

@@          Coverage Diff          @@
##             v4     #439   +/-   ##
=====================================
  Coverage      ?   94.02%           
=====================================
  Files         ?        2           
  Lines         ?     1072           
  Branches      ?      139           
=====================================
  Hits          ?     1008           
  Misses        ?       64           
  Partials      ?        0           

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