FA-205 / Encodings / Member archive
BOM cleanup removes a legitimate character inside the document · case 05
A leading encoding signature is exposed as text, or cleanup also strips matching interior characters.
Case contract
Decode UTF-8 bytes, removing at most one EF BB BF signature at the start. Preserve every subsequent U+FEFF character; return None for invalid UTF-8.
Why this case matters
Encoding signatures are positional metadata. Global text cleanup cannot preserve the distinction between metadata and document content.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| leading BOM removed | "\ufeffpartpartpartpartpart" | "partpartpartpartpart" | Failed |
MEMBER ARCHIVE
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