Definitions of the terms used across the a2a-wrapper docs. A2A, agent card, task, artifact, context, executor, sideband event, sub-agent, MCP, skill, and more.

A2A (Agent2Agent). An open protocol for agents to discover each other and exchange tasks over HTTP. See What is A2A?.

Agent card. JSON at /.well-known/agent-card.json describing an agent's name, skills and endpoints. See agent cards.

Artifact. An output of a task, delivered as parts. The final answer is normally an artifact.

Backend. The agent product a wrapper exposes: Copilot, Claude, Codex, OpenCode or Antigravity.

BYOK (bring your own key/model). Pointing a2a-copilot at your own provider, such as Ollama, OpenAI, Anthropic or Azure, instead of GitHub Copilot's hosted models.

Canary. An unreviewed npm release published after every merge to main. Installed with @canary.

Context / contextId. An identifier grouping related messages into one conversation. Wrappers map it to a backend session. See sessions.

Core (@a2a-wrapper/core). The shared package holding all protocol, server, config, session and event logic.

Executor. The backend-specific class a wrapper implements (A2AExecutor) to run tasks.

JSON-RPC. The message format for A2A's primary transport. The endpoint is /a2a/jsonrpc.

MCP (Model Context Protocol). An open protocol for connecting agents to tools and data. A2A is its horizontal counterpart. See MCP tool servers.

Message. One turn of communication, made of parts, with a user or agent role.

Orchestrator. A client or framework that discovers agents and delegates work to them.

Permission mode / sandbox mode. Controls on what a backend may do in the workspace, for example permissionMode in a2a-claude and sandboxMode in a2a-codex. See the security guide.

Sideband event. An observability event (tool call, reasoning, file change, usage) emitted alongside the answer. See observability.

Skill (agent card). A capability advertised to callers for discovery and routing.

Skill (memory). A SKILL.md folder of instructions written into the workspace for the model. See memory and skills.

Sub-agent. A remote A2A agent a wrapper exposes to its model as tools. See sub-agents.

Task. A unit of work with a lifecycle: submitted, working, input-required, completed, failed or canceled.

Workspace. The directory a wrapper's agent may read and modify, set with WORKSPACE_DIR.

Glossary