> ## 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.

# Decision model pricing

## Overview

Estimate cost from provider-reported usage and the pricing snapshot attached to
an exact Decision model record. Unknown paid usage returns no estimate. An
explicit zero rate remains known free and does not require a token count.

## Example

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

use Cognesy\Polyglot\Decision\Data\DecisionPricing;
use Cognesy\Polyglot\Decision\Data\DecisionUsage;
use Cognesy\Polyglot\Decision\Models\ModelCatalog;
use Cognesy\Polyglot\Decision\Pricing\FlatRateCostCalculator;

$models = ModelCatalog::discover();
$jev = $models->find('typesafe', 'jev-1.13.0');
$pricing = $jev->pricing;

if ($pricing === null) {
    throw new RuntimeException('No reviewed pricing is available for this exact model.');
}

$calculator = new FlatRateCostCalculator;
$reportedUsage = new DecisionUsage(inputTokens: 25_000, outputTokens: null);
$cost = $calculator->calculate($reportedUsage, $pricing);

echo "Jev pricing snapshot (USD per 1M tokens):\n";
echo json_encode($pricing->toArray(), JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR)."\n";
echo 'Estimated cost: '.($cost?->toString() ?? 'unavailable')."\n\n";

$unavailable = $calculator->calculate(
    new DecisionUsage(inputTokens: null, outputTokens: null),
    $pricing,
);
$knownFree = $calculator->calculate(
    new DecisionUsage(inputTokens: null, outputTokens: null),
    new DecisionPricing(inputPerMToken: 0, outputPerMToken: 0),
);

echo 'Unknown paid input usage: '.($unavailable?->toString() ?? 'unavailable')."\n";
echo 'Explicitly free rates: '.($knownFree?->toString() ?? 'unavailable')."\n";

assert($pricing->inputPerMToken === 0.042);
assert($pricing->outputPerMToken === 0.0);
assert($cost?->total === 0.00105);
assert($unavailable === null);
assert($knownFree?->total === 0.0);
?>
```