EP-5 Encoding is judged on bytes

An encoding defect MUST NOT be filed or fixed until its bytes have been checked at each boundary the text crossed, the agent's own tools included.

Field	Value
Keyword	MUST NOT
Level	2
Checked	by judgement
Findings	F405, F404
Harness facts	none
Threat	construct: both cases were caught within hours, so the cost recorded is small
Status	active

Rationale: in polyweave and in Shio, a month apart, the first diagnosis of corrupted text blamed the component that displayed it, and relocating the fault reversed a fix already shipped in one case and retired a filed defect in the other (F405, R3/S2). What moved each diagnosis was checking the bytes at every hop; Shio's first reading had measured bytes along the product's path and still missed the agent's own tool in it. Shio wrote the rule down as "judge encoding on bytes with od -c rather than on what a terminal prints" [shio@c17ed995a], because "A filed defect that does not exist costs whoever picks it up more than the bug would have" [shio@c17ed995a]. A terminal renders both good and damaged bytes through its own decode, which on the corpus's Windows machines was the locale's (F404).