itd-2610161733316518 turns off the host fallback inside a matrix cell; invariant 2 says a missing or failing adapter degrades to the native path, and the brief declares no exception for this.

itd-2610161733316518 turns off the host fallback inside a matrix cell; invariant 2 says a missing or failing adapter degrades to the native path, and the brief declares no exception for this.

A premise contradiction (severity minor) found by the cross-document consistency pass.

• End A: .abcd/development/intents/planned/itd-2610161733316518-a-product-thinker-who-wants-to-know.md:239 — "Inside a matrix cell it switches off the host fallback"
• End B: .abcd/development/brief/02-constraints/03-invariants.md:11 — "A missing or misbehaving adapter degrades to the native path; abcd never blocks on an absent tool."

The model-matrix intent's decision 4 says 'Inside a matrix cell it switches off the host fallback' that the runners and routing table otherwise take, scores a failed cell as a failure, and argues that invariant 2's purpose still holds. Invariant 2 states 'A missing or misbehaving adapter degrades to the native path; abcd never blocks on an absent tool.' with no carve-out. A route that deliberately does not degrade contradicts the invariant as written until the brief declares the exception, as it declares other exceptions to adr-22.

Evidence: .abcd/work/reviews/2026-10-26-consistency/00-summary.md, finding 194.