> ## Documentation Index
> Fetch the complete documentation index at: https://docs.instructorphp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Composer capability discovery

## Overview

Trusted packages can publish zero-argument agent capabilities in Composer's
`extra.cognesy-agents.capabilities` map. `CapabilityDiscovery` reads those
manifests and registers lazy factories that definitions can reference by name.
Discovery is explicit because resolving a contributed entry instantiates code
from that package.

The fixture used by this credential-free example declares one root-package
capability:

```json theme={null}
{
  "name": "example/agent-extension",
  "extra": {
    "cognesy-agents": {
      "capabilities": {
        "system-prompt": "Cognesy\\Agents\\Capability\\Prompt\\UseSystemPrompt"
      }
    }
  }
}
```

## Example

```php theme={null}
<?php
require 'examples/boot.php';

use Cognesy\Agents\Capability\AgentCapabilityRegistry;
use Cognesy\Agents\Collections\NameList;
use Cognesy\Agents\Discovery\CapabilityDiscovery;
use Cognesy\Agents\Discovery\PackageManifest;
use Cognesy\Agents\Template\Data\AgentDefinition;
use Cognesy\Agents\Template\Factory\DefinitionLoopFactory;
use Cognesy\Agents\Tool\ToolRegistry;

$fixture = __DIR__ . '/fixture';
$capabilities = new AgentCapabilityRegistry();
$tools = new ToolRegistry();

$result = CapabilityDiscovery::discover(
    $capabilities,
    $tools,
    vendorDir: $fixture . '/vendor',
    rootComposerPath: $fixture . '/composer.json',
);

$definition = new AgentDefinition(
    name: 'manifest-agent',
    description: 'Uses a capability contributed through Composer metadata.',
    systemPrompt: 'Answer concisely.',
    capabilities: new NameList('system-prompt'),
);
$agent = (new DefinitionLoopFactory($capabilities, $tools))
    ->instantiateAgentLoop($definition);

echo json_encode([
    'packages' => array_map(
        static fn (PackageManifest $manifest): string => $manifest->packageName,
        $result->manifests()->all(),
    ),
    'capabilities' => $result->capabilities()->all(),
    'errors' => $result->errors()->all(),
], JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR), "\n";

assert($result->capabilities()->all() === ['system-prompt']);
assert($result->errors()->isEmpty());
assert($capabilities->has('system-prompt'));
assert(count($agent->profile()->capabilities->all()) === 1);
?>
```