chore: add crewai-a2a package README

lib/crewai-a2a/README.md

@@ -0,0 +1,189 @@
+# crewai-a2a
+
+Agent-to-Agent (A2A) protocol support for CrewAI. Enables agents to discover, authenticate, and communicate with remote A2A-compatible agents.
+
+## Quick Links
+
+[Homepage](https://www.crewai.com/) | [Documentation](https://docs.crewai.com/) | [Community](https://community.crewai.com/)
+
+## Installation
+
+```bash
+uv pip install crewai[a2a]
+# or
+uv add 'crewai[a2a]'
+```
+
+## Usage
+
+### Connecting to a Remote A2A Agent
+
+```python
+from crewai import Agent
+from crewai_a2a import A2AClientConfig
+
+agent = Agent(
+    role="Coordinator",
+    goal="Delegate research tasks",
+    a2a=[
+        A2AClientConfig(endpoint="https://research-agent.example.com"),
+    ],
+)
+```
+
+### Exposing an Agent as an A2A Server
+
+```python
+from crewai import Agent
+from crewai_a2a import A2AServerConfig
+
+agent = Agent(
+    role="Researcher",
+    goal="Answer research questions",
+    a2a_server=A2AServerConfig(
+        name="Research Agent",
+        description="Answers research questions using web search",
+    ),
+)
+```
+
+## Authentication
+
+### Client Schemes
+
+```python
+from crewai_a2a.auth import (
+    BearerTokenAuth,
+    HTTPBasicAuth,
+    APIKeyAuth,
+    OAuth2ClientCredentials,
+)
+from crewai_a2a.config import A2AClientConfig
+
+# Bearer token
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    auth=BearerTokenAuth(token="my-token"),
+)
+
+# API key
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    auth=APIKeyAuth(api_key="key", location="header", name="X-API-Key"),
+)
+
+# OAuth2 client credentials
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    auth=OAuth2ClientCredentials(
+        token_url="https://auth.example.com/token",
+        client_id="id",
+        client_secret="secret",
+    ),
+)
+```
+
+### Server Schemes
+
+```python
+from crewai_a2a.auth import SimpleTokenAuth, OIDCAuth
+from crewai_a2a.config import A2AServerConfig
+
+# Simple token validation
+A2AServerConfig(auth=SimpleTokenAuth(token="expected-token"))
+
+# OpenID Connect
+A2AServerConfig(
+    auth=OIDCAuth(
+        issuer="https://auth.example.com",
+        audience="my-agent",
+    ),
+)
+```
+
+## Update Mechanisms
+
+Control how the client receives task updates from remote agents.
+
+```python
+from crewai_a2a.updates import PollingConfig, StreamingConfig, PushNotificationConfig
+from crewai_a2a.config import A2AClientConfig
+
+
+# Polling
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    updates=PollingConfig(interval=2.0, timeout=60),
+)
+
+# Server-Sent Events streaming
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    updates=StreamingConfig(),
+)
+
+# Webhook push notifications
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    updates=PushNotificationConfig(
+        url="https://my-server.example.com/webhook",
+        timeout=300,
+    ),
+)
+```
+
+## Extensions
+
+### Client Extensions
+
+Client extensions inject tools, augment prompts, and process responses.
+
+```python
+from crewai_a2a.extensions import A2AExtension
+
+
+class MyExtension(A2AExtension):
+    def inject_tools(self, agent):
+        ...
+
+    def augment_prompt(self, base_prompt, conversation_state):
+        return f"{base_prompt}\n\nAdditional context from extension."
+```
+
+### Server Extensions
+
+Server extensions add protocol-level capabilities to your A2A server.
+
+```python
+from crewai_a2a.extensions import ServerExtension
+
+class MyServerExtension(ServerExtension):
+    uri = "urn:my-org:my-extension"
+    description = "Custom protocol extension"
+
+    async def on_request(self, context):
+        ...
+
+    async def on_response(self, context, result):
+        ...
+```
+
+## Transport
+
+Three transport protocols are supported: JSON-RPC (default), gRPC, and HTTP+JSON.
+
+```python
+from crewai_a2a.config import ClientTransportConfig, GRPCClientConfig
+from crewai_a2a.config import A2AClientConfig
+
+
+A2AClientConfig(
+    endpoint="https://agent.example.com",
+    transport=ClientTransportConfig(
+        preferred="GRPC",
+        grpc=GRPCClientConfig(
+            max_send_message_length=4 * 1024 * 1024,
+        ),
+    ),
+)
+```