# A2ADemo

IEx test harness for the A2A protocol. Provides two demo functions that exercise the full agent discovery → task send → task retrieval flow.

## Functions

### `run_local()`

Direct module calls — no HTTP, no server required. Uses a hardcoded user (ID 1) with admin permissions. Exercises `A2AServer` functions directly.

**Flow:**
1. `A2AServer.agent_card/1` — discover skills for the user
2. `A2AServer.handle_send/2` — send `add_numbers(3, 7)` task
3. `A2AServer.handle_get/2` — retrieve the task by ID

```elixir
iex> A2ADemo.run_local()

=== A2A Local Demo ===

1. Agent Card (Discovery):
   Name: elixir-mcp-agent
   Skills: 42
     - add_numbers: Add two numbers together
     ...

2. Sending task (add_numbers 3 + 7):
   Task ID: 1709395200000
   State: completed
   Result: 10

3. Retrieving task:
   State: completed
   Timestamp: 2026-03-02T12:00:00.000Z

=== Demo Complete ===
```

### `run(cookie \\ nil)`

Full HTTP round-trip via `A2AClient`. Requires the HTTPS server to be running on `https://localhost` and a valid authentication cookie.

**Flow:**
1. `A2AClient.discover/1` — public agent card (no auth)
2. `A2AClient.send_task/3` — send `add_numbers(5, 12)` with cookie auth
3. `A2AClient.get_task/3` — retrieve the task by ID

Without a cookie, only discovery runs. Authenticated steps are skipped with a message.

```elixir
iex> A2ADemo.run(cookie)

=== A2A HTTP Demo ===

1. Discovering agent at https://localhost:
   Name: elixir-mcp-agent
   URL: https://localhost/a2a
   Skills: 5
     - get_greeting: Returns a greeting message
     ...

2. Sending task (add_numbers 5 + 12):
   Task ID: 1709395200000
   State: completed
   Result: 17

3. Retrieving task 1709395200000:
   State: completed
   Timestamp: 2026-03-02T12:00:00.000Z

=== Demo Complete ===
```

## Generating a Cookie

From IEx:

```elixir
{:ok, user} = User.find_by_username("james")
secret = Plug.Crypto.KeyGenerator.generate(
  Application.get_env(:mcp, :secret_key_base),
  Application.get_env(:mcp, :cookie_salt),
  length: 32
)
cookie = Plug.Crypto.MessageEncryptor.encrypt(
  to_string(user.id),
  secret,
  Application.get_env(:mcp, :cookie_salt)
)

A2ADemo.run(cookie)
```

## Why Two Modes

- **`run_local/0`** — fast feedback during development, no network dependencies, tests `A2AServer` logic in isolation
- **`run/1`** — validates the full stack: HTTP routing, cookie authentication, TLS, JSON-RPC serialization, and `A2AClient` correctness

## Source

`lib/a2a_demo.ex`