Every consequential agent action crosses one governed boundary.
NEXUS-A2A wraps the protocols and frameworks you already run in a sovereign execution envelope. Before an action reaches production, NEXUS authenticates the agent, verifies delegated authority, validates memory provenance, evaluates policy, preserves human control, and generates non-repudiable evidence.
Nothing acts beyond delegated authority. Scope can narrow. It cannot silently expand.
Six invariants. None optional.
A connected agent fleet is not necessarily a sovereign agent fleet. NEXUS requires all six conditions at the boundary.
Authenticated Borders
Every agent proves its identity at every trust boundary through verifiable identity and workload credentials.
Monotonic Scope
Delegated authority may narrow. It may never expand silently as work passes between agents.
Memory Provenance
Persistent memory writes require attributable ownership and integrity evidence. Manipulation becomes detectable.
Physical Kill Switch
Consequential agents retain a registered stop path outside the agent’s own control.
Owner of Record
Every agent is bound to an accountable human owner. Autonomy never becomes ownerless authority.
Drift as Security Event
Behavioral drift is handled as a security condition, not merely a model-performance statistic.
Your agents can already do everything. Except prove it.
But answer these questions:
Sovereignty is not.
Every connectivity protocol gets agents talking. None of them establish who an agent is, what it may do, or whether it can be held to account.
This comparison describes capabilities natively formalized by each protocol. Individual implementations may add external controls. MCP, ACS, and A2A solve different problems — NEXUS wraps them; it does not replace them.
It wraps them.
Model portability changes where intelligence can run. It does not prove who authorized an action, whether authority expanded, whether memory was manipulated, or whether the decision can be revoked and reconstructed.
Model sovereignty begins with portability. Execution sovereignty requires architecture.
Six layers. One sovereign execution protocol.
Each layer closes a different trust failure. Together they make agent authority attributable, bounded, revocable, and provable.
Transport Security
Establishes an authenticated, encrypted border between participating workloads. PQC-ready by design.
Identity & Delegation
Proves who the agent is, who authorized it, and how much authority it received.
Policy Enforcement
Evaluates each consequential action before execution — and fails closed when enforcement is unavailable.
Memory & Context
Validates memory writes, records provenance, and surfaces behavioral drift or supply-chain changes.
Economic Governance
Accounts for resource consumption and prevents unconstrained autonomous spending or compute use.
Governance Plane
Preserves human override, constitutional constraints, and controlled protocol evolution.
L1–L6 is the defined NEXUS-A2A architecture. Read the specification →
Security shouldn't require rebuilding everything.
You already invested in your stack. NEXUS works with all of it.
Install
One pip install drops the SDK into the environment you already run. No infrastructure to stand up.
Wrap
NEXUS sits underneath your existing protocols and agents. Your architecture stays exactly as it is.
Enforce
Identity, delegation, memory, and policy execute at runtime. Blocked before execution, not after the incident.
MCP connects agents to tools. NEXUS proves which agent is acting.
MCP standardizes capability access. NEXUS adds verifiable agent identity, bounded delegation, memory provenance, policy enforcement, and non-repudiable evidence — without changing the MCP architecture.
ACS enforces the call. NEXUS makes the authority provable.
ACS establishes an important runtime policy point. NEXUS extends it with cryptographic identity, monotonic delegation, governed memory, accountable human ownership, and durable evidence across the complete agent chain.
Every workflow eventually reaches the same question: who approved this action? And immediately after: can we prove it?
NEXUS makes the answer yes.
Join practitioners governing their agent stacks with NEXUS.
Open source, actively developed, and built in the open. Community is signal — not social proof.
The short answer is almost always no rebuild.
Connected agents are not accountable agents.
Install the SDK. Wrap one high-risk workflow. Verify the agent, authority, memory, policy decision, and evidence chain — then expand across the fleet.
pip install nexus-a2a-sdk
Not sure where your agent stack stands? Start with a free AI governance assessment.