Schema::toSchema() includes `name` property inside schema array, breaking OpenRouter structured output

[Peppe2404]

Description

When using HasStructuredOutput agents with the OpenRouter provider, structured output requests fail
with:

OpenRouter Bad Request: output_format.schema: For 'object' type, property 'name' is not supported

The root cause is that Schema::toSchema() includes the name metadata field inside the JSON Schema
array, which is not a valid JSON Schema property for object type.

Root Cause

In src/Schema.php, the toSchema() method returns:

public function toSchema(): array
{
    return [
        'name' => $this->name,
        ...$this->schema->toArray(),
    ];
}

Prism's OpenRouter Structured handler (src/Providers/OpenRouter/Handlers/Structured.php) calls both
$request->schema()->name() and $request->schema()->toArray():

'response_format' => [
    'type' => 'json_schema',
    'json_schema' => [
        'name' => $request->schema()->name(),   // ✅ name at wrapper level
        'strict' => true,
        'schema' => $request->schema()->toArray(), // ❌ also contains 'name'
    ],
],

This results in name appearing twice in the payload — once correctly at the json_schema level (added
by Prism), and once incorrectly inside the schema object (from Laravel AI SDK's toSchema()):

{
  "response_format": {
    "type": "json_schema",
    "json_schema": {
      "name": "schema_definition",
      "strict": true,
      "schema": {
        "name": "schema_definition",
        "type": "object",
        "properties": { "..." },
        "required": ["..."]
      }
    }
  }
}

OpenRouter rejects this because name is not a valid property for a JSON Schema of type object.

Suggested Fix

Remove name from toSchema() / toArray() — these methods should return a pure JSON Schema without
metadata:

public function toSchema(): array
{
    return $this->schema->toArray();
}

The name is already accessible via the dedicated name() method, which Prism correctly calls
separately.

Related

This is architecturally similar to #139 (Gemini fails with additionalProperties leaking through the
same serialization path).

Reproduction

Any agent using HasStructuredOutput targeting OpenRouter:

class StrategyAgent implements Agent, HasStructuredOutput
{
    use Promptable;

    public function schema(JsonSchema $schema): array
    {
        return [
            'queries' => $schema->array()
                ->items($schema->string())
                ->description('A list of search queries.'),
        ];
    }
}

// Trigger:
$agent->prompt(prompt: 'Generate queries.', model: 'anthropic/claude-sonnet-4.5');

Versions

- laravel/ai: v0.1.5
- prism-php/prism: v0.99.19
- PHP: 8.4
- Provider: OpenRouter