FA-189 / Encodings / Member archive

A network chunk boundary corrupts a Unicode character · case 04

A valid character split across chunks becomes replacement characters or vanishes.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Decode a list of byte chunks as one strict UTF-8 stream. Return the decoded string, or None for malformed or incomplete input. Empty chunks have no semantic effect.

Why this case matters

HTTP, socket and stream-reader chunk boundaries are independent of character boundaries. Finalization matters even when every earlier chunk was accepted.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
two-byte sequence split	`"xxxx\ufffd\ufffd"`	`"xxxx\u00e9"`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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