[ Download version 2 for Updated solution ] Summary : Regulators now require that third-party AI assistants receive the same execution access as a platform’s own first-party assistant — whether that is Apple’s Siri or Google’s Android AI agents. Platform operators require that this access never become uncontrolled power over irreversible actions: payments, messages, file exports, credential release, sensor capture, or device actuation. Every current solution lives in software: permission dialogs, entitlement systems, OAuth scopes, developer policies, App Tracking Transparency-style prompts. They all share the same structural failure. The same software layer that grants access also controls how that access is described, audited, and revoked. A platform cannot independently prove it gave genuine parity to a competitor when it remains the only party that can change the rules. The missing mechanism is absolute: separate the request for a device action from the authority to perform it — at the hardware level, for every assistant equally. Treat every device-side action, no matter which app, Siri extension, or AI agent requests it, as a Candidate Act held in a non-effective state. Before it can execute, a hardware-isolated domain (Secure Enclave, TrustZone, StrongBox, Titan M) independently validates a fixed set of predicates: application identity, declared purpose, resource scope, destination, runtime behaviour, and freshness. Only when every predicate passes does the domain release a scoped, single-use, non-transferable capability bound to that one act. The operating system can route requests and carry the capability object. It cannot mint it, expand it, reinterpret it, or force its acceptance. Final authority sits outside the OS. At the exact moment the action would take effect, a Finality Sink re-checks the capability. If anything has drifted — identity, scope, destination, or freshness — the action is refused. No partial execution. No silent fallback. Fail closed. First-party and third-party assistants (Siri and Android AI agents alike) are evaluated under identical hardware predicates. Regulators get verifiable parity they no longer have to take on trust. Platform operators get a guarantee that no assistant, including their own, can ever obtain uncontrolled execution authority — because requesting an action is never the same thing as making it happen. This is the architecture that makes both regulatory interoperability and real security simultaneously true. Independent Research Disclaimer: This technical architecture and its associated specifications represent independent, preliminary research. This work has not been peer-reviewed by an academic journal or formal standards body and is published solely as an open contribution to ongoing public and regulatory policy discussions regarding the Digital Markets Act (DMA) and platform interoperability. Performance & Latency Variability: All performance metrics, throughput estimations, and latency characteristics described herein are conceptual. Actual execution latency, overhead, and behavior may vary significantly in a real-world, production-grade operating system environment depending on hardware heterogeneity, system load, secure enclave constraints, and platform-specific kernel implementations. No guarantees of real-time performance bounds are implied.