BR-CO-10: Line net amount sum mismatch
Severity: error
What it means
Sum of Invoice line net amount (BT-106) does not equal the sum of the individual Invoice line net amounts (BT-131).
Most common cause
The header LineExtensionAmount was edited independently of the invoice lines (e.g. off by a rounding cent), or a line was added or removed without recalculating the header total.
How to fix it
Recalculate LineExtensionAmount as the exact sum of all line net amounts at the source system and re-issue the invoice. Not auto-repaired: this is an arithmetic mismatch (CLAUDE.md invariant) and is reported expected-vs-found, never patched.