Being Reasonable Is Not Enough: Measuring Selective Relationship Conditioning in Full-Duplex Speech Agents

Full-duplex speech agents must decide not only whether a conversational moment permits a response, but whether the same moment warrants a different action for a friend, supervisor, or task owner. Ordinary action accuracy cannot isolate this capability because a locally acceptable default may ignore the relationship condition. We introduce the Relationship Permission Boundary (RPB), a paired counterfactual benchmark that holds decision-preceding audio fixed while changing only the interlocutor relationship. Directional Correct Adaptation (DCA) requires both sides to be acceptable and any action change to follow the reviewed direction. On 79 human-reviewed strong pairs, three native audio systems obtain only 0–3.8% DCA although condition-level acceptable accuracy reaches 31.6–75.3%; a constant WAIT policy reaches 88.0% Acceptable with DCA 0. A concise training analysis identifies three recurring shortcuts: local fit without selective transfer, direction without invariant safety, and safety through zero-change collapse. We then train a detachable relationship FiLM router, speech-activity feature encoder, and paired action head using frozen MiniCPM-o-4.5 text scores. On a participant-isolated AMI Train-only endpoint, all three seeds obtain DCA 1, balanced safe utility 1, coverage 0.444444, exact 1, and zero harm or invalid change. The frozen base has DCA 0 and utility 0.638889; an equal-capacity relation-blind control has DCA 0 and utility 0.666667. Both nine-meeting recording-blocked tests give p = 0.0020999. Training and confirmation share a deterministic four-state/action mapping, so this is a policy-contract result, not evidence of learned human permission boundaries or audio-conditioned adaptation. A post-hoc exploratory audit supports dependence on supplied state and side binding; acoustic-feature nulling is unchanged (p = 1.0). The contribution is an auditable benchmark specification, a shortcut diagnosis, and bounded evidence of structured-state use.