The ingest verb's missing-body-field guard is mutation-vacuous: removing it (checkItem's len(missing) > 0 branch) leaves every test in internal/core/reading green. No case builds an item that carries the position's own body but leaves one declared field empty or absent, because TestWrongPositionBodyIsUndecodable supplies a FOREIGN body and the unknown-key check fires first. The guard is the one that would catch a reading returning a partial item at its own position.

The ingest verb's missing-body-field guard is mutation-vacuous: removing it (checkItem's len(missing) > 0 branch) leaves every test in internal/core/reading green. No case builds an item that carries the position's own body but leaves one declared field empty or absent, because TestWrongPositionBodyIsUndecodable supplies a FOREIGN body and the unknown-key check fires first. The guard is the one that would catch a reading returning a partial item at its own position.

Grounds

• pursued: a guard proved by mutation rather than by a passing test, so the case fails without it; a later mutation run finding it survived again would show this wrong