wehub-resource-sync
114 lines
6.1 KiB
Markdown
114 lines
6.1 KiB
Markdown
# Architecture & Packages
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## Three-Layer Architecture
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```
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Frontend (React/Angular/Vanilla) → Runtime (Express/Hono server) → Agent (LangGraph/CrewAI/BuiltIn/Custom)
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```
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All layers communicate via the **AG-UI protocol** — an event-based standard streamed over SSE.
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## Package Structure
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All packages live flat under `packages/` using the `@copilotkit/` scope. There is no v1/v2 split — the codebase is consolidated.
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## Packages
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- **shared**: Common utilities, types, and constants used across all other packages.
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- **core**: The `CopilotKitCore` orchestrator — the central brain on the frontend. Manages the agent registry, tool registry, context store, and event subscriptions. All framework packages (React, Angular, Vanilla) wrap this.
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- **react-core**: The public `<CopilotKit>` provider and hooks. Wraps core for React.
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- **react-ui**: Chat UI components — `CopilotChat`, `CopilotPopup`, `CopilotSidebar`, `CopilotPanel`.
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- **react-textarea**: The `CopilotTextarea` component for AI-assisted text editing.
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- **angular**: Angular DI tokens, services, and signal-based state. Same concepts as React but using Angular patterns (`inject()`, signals, `AgentStore`).
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- **runtime**: The server-side `CopilotRuntime` class that receives HTTP requests and delegates to agents. Provides Express and Hono adapters. Contains the `AgentRunner` abstraction for managing thread/conversation state. Also includes GraphQL server and LLM adapters.
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- **runtime-client-gql**: urql-based GraphQL client for frontend-to-runtime communication.
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- **agent**: The `BuiltInAgent` — a default agent implementation powered by the Vercel AI SDK. Used when developers don't bring their own agent framework.
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- **voice**: Voice input and transcription support.
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- **web-inspector**: A debug console (Lit web component) for inspecting agent communication in development.
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- **sqlite-runner**: An `AgentRunner` implementation that persists thread state to SQLite instead of memory.
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- **sdk-js**: Helpers for LangGraph/LangChain agent integration.
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## Request Lifecycle
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1. **Init**: Frontend creates `CopilotKitCore` → fetches agent info from runtime → creates a `ProxiedAgent` instance per remote agent.
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2. **User sends message**: Message is added to the agent, then `runAgent()` is called.
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3. **HTTP request**: A POST is sent to the runtime with a `RunAgentInput` payload containing messages, registered tools, context, threadId, and state.
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4. **Runtime processing**: Request middleware runs → agent is resolved and cloned → `AgentRunner` executes the agent.
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5. **SSE stream back**: Agent emits AG-UI events streamed to the frontend: run lifecycle events, text message chunks (streaming), and optional tool call events.
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6. **Frontend tool execution**: When the agent calls a frontend tool, Core looks up the handler in its registry, executes it locally in the browser, and sends the result back to the agent which continues processing.
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7. **UI update**: Core updates its message store and notifies subscribers → React/Angular re-renders.
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## Core Concepts
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### AG-UI Protocol
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All agent↔UI communication is event-based. Events follow a structured lifecycle: `RUN_STARTED` → `STEP_STARTED` → message/tool events → `STEP_FINISHED` → `RUN_FINISHED`. Events are streamed over SSE and validated with Zod schemas. The `EventType` enum in `@ag-ui/core` defines all event types.
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### ProxiedAgent
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The frontend representation of a remote agent. Implements the `AbstractAgent` interface but translates calls into HTTP requests to the runtime, streaming SSE events back. Created automatically when the runtime reports available agents.
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### AgentRunner
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An abstract class on the runtime side responsible for managing thread state (conversation history, agent state). The default `InMemoryAgentRunner` is ephemeral; `SQLiteAgentRunner` provides persistence. Custom runners can be built for any storage backend.
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### Tool Registration
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Tools can be **frontend tools** (handler runs in the browser, registered via `useFrontendTool`) or **backend tools** (handler runs on the server, defined in the agent config). Tools can be scoped to a specific agent via `agentId`, or available to all agents by omitting it.
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### Context
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Application data sent alongside messages to give agents awareness of the current UI state. Registered via `useAgentContext(description, data)` where data is any JSON-serializable value. Automatically included in every agent run.
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### Multi-Agent
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Multiple agents can be registered in a single `CopilotRuntime`. Each agent gets its own endpoint, message thread, state, and optionally scoped tools. The frontend selects which agent to interact with via `useAgent({ agentId })`.
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### Middleware
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`CopilotRuntime` supports `beforeRequestMiddleware` and `afterRequestMiddleware` for cross-cutting concerns like authentication, logging, and request/response transformation.
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## Debug Mode
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CopilotKit includes a built-in debug mode for both the runtime and client that provides detailed logging of the AG-UI event pipeline.
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### Enabling Debug Mode
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**Runtime (server-side):**
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```ts
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const runtime = new CopilotRuntime({
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debug: true, // Full debug output with Pino structured logging
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});
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```
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**Client (React):**
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```tsx
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<CopilotKit debug={true} runtimeUrl="...">
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{children}
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</CopilotKit>
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```
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### Granular Configuration
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Both accept a config object for fine-grained control:
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```ts
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debug: {
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events: true, // Log every event emitted/received (default: true)
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lifecycle: true, // Log request/run lifecycle (default: true)
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verbose: false, // Log full payloads vs summaries (default: false in object form, true in boolean form)
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}
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```
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### What Gets Logged
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**Runtime:** Agent run started, SSE stream opened/completed/errored, every AG-UI event emitted (with Pino structured logger).
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**Client:** The debug configuration is forwarded to the AG-UI transport layer (`transformChunks`). CopilotKit itself does not currently emit client-side `console.debug` calls — the flag configures the underlying AG-UI event pipeline for transport-level debug output.
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### Architecture
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The `DebugConfig` type and `resolveDebugConfig()` normalizer live in `@copilotkit/shared`. The runtime and client toggles are independent — enabling one does not affect the other.
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