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A2A bridge

Purpose

Agentweaver keeps workflow orchestration on worker pods. It sends each leaf agent turn to AgentHost over A2A HTTP+JSON. The orchestration graph, approval gates, checkpoints, and durable events do not cross this boundary.

RemoteAgentProxy implements the workflow agent surface on the worker. It forwards a turn, receives streamed output and run events, and re-emits them to the local runtime.

AgentHost hosts an A2ATurnBridgeAgent around the provider-backed runtime. It exposes POST /a2a/agent/v1/message:stream and GET /a2a/agent/v1/card on port 8088 by default.

Workflow agents

RemoteWorkflowAgentFactory returns RemoteAgentProxy for five workflow agents:

  • worker
  • RAI
  • Rubberduck
  • Build/Test
  • Scribe

The Operator Assistant also uses RemoteAgentProxy, outside IWorkflowAgentFactory.

Turn and event transport

The worker sends turn setup as the first A2A DataContent part. This setup contains workspace and repository context, model and system-prompt data, project and agent identity, and revision state.

AgentHost sends assistant updates and structured RunEvent values through the same stream. RunEventDataPartCodec serializes the run events, which the worker appends to its local event pipeline.

Warm-pool configuration

AgentHost starts in standby without a run identity. When the API claims a warm pod, it makes one POST /configure request. The request includes run, project, agent, and purpose identity; shared and local workspace descriptors; turn authentication; approval settings; and provider configuration.

The provider payload is either copilotCredential or byokProviderConfiguration. Repository, preview, and MCP broker credentials are optional and purpose-scoped.

/configure is protected by the in-cluster NetworkPolicy because it delivers the turn credential. It accepts one configuration per pod. After configuration, /healthz reports ready and AgentHost accepts only A2A turns with the configured per-run bearer token.

Security boundary

The sandbox pod has no database connection and does not hold an ICheckpointStore. It cannot retrieve ambient user credentials from Key Vault, CSI volumes, shared storage, or host configuration.

The A2A turn token is unique to the run. A token from one pod cannot authorize a turn against another pod.

Source

  • apps/Agentweaver.Api/Sandbox/RemoteWorkflowAgentFactory.cs
  • apps/Agentweaver.Api/Sandbox/KubernetesSandboxExecutor.cs
  • apps/Agentweaver.AgentHost/Program.cs
  • apps/Agentweaver.AgentHost/A2ATurnBridgeAgent.cs

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