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Fix malformed json_schema envelope for OpenAI-compatible providers #251

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Fix malformed json_schema envelope for OpenAI-compatible providers #251

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617ec60
Fix malformed json_schema envelope for OpenAI-compatible providers
alewolf Jun 4, 2026
96b5dda
Use a fixed, spec-valid json_schema name instead of the schema title
alewolf Jun 4, 2026
b3c6845
Address review feedback: clarify null check and pass-through condition
alewolf Jun 4, 2026
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27 changes: 24 additions & 3 deletions src/Providers/OpenAiCompatibleImplementation/AbstractOpenAiCompatibleTextGenerationModel.php
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Original file line number Diff line number Diff line change
Expand Up @@ -504,7 +504,14 @@ protected function prepareToolsParam(array $functionDeclarations): array
/**
* Prepares the response format parameter for the API request.
*
* This is only called if the output MIME type is `application/json`.
* This is only called if the output MIME type is `application/json`. When an output schema is
* provided, it is wrapped in the `json_schema` envelope expected by the OpenAI Chat Completions
* API, which requires a `name` field and the schema under the `schema` key. The `name` uses a
* fixed identifier that satisfies the API's `^[a-zA-Z0-9_-]{1,64}$` constraint, rather than a
* value derived from the schema, to avoid producing an invalid name. If a caller already
* supplies a wrapped payload (i.e. an array containing both `name` and `schema` keys), it is
* passed through unchanged, allowing callers to opt into provider-specific options such as
* `strict`.
*
* @since 0.1.0
*
Expand All @@ -513,15 +520,29 @@ protected function prepareToolsParam(array $functionDeclarations): array
*/
protected function prepareResponseFormatParam(?array $outputSchema): array
{
if (is_array($outputSchema)) {
if ($outputSchema === null) {
return [
'type' => 'json_object',
];
}

// Pass through payloads that are already wrapped in the json_schema envelope.
$isWrappedEnvelope = isset($outputSchema['name'])
&& isset($outputSchema['schema'])
&& is_array($outputSchema['schema']);
if ($isWrappedEnvelope) {
return [
'type' => 'json_schema',
'json_schema' => $outputSchema,
];
}

return [
'type' => 'json_object',
'type' => 'json_schema',
'json_schema' => [
'name' => 'response_schema',
'schema' => $outputSchema,
],
];
}

Expand Down
77 changes: 75 additions & 2 deletions ...viders/OpenAiCompatibleImplementation/AbstractOpenAiCompatibleTextGenerationModelTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -418,7 +418,16 @@ public function testPrepareGenerateTextParamsWithJsonOutputSchema(): void
$params = $model->exposePrepareGenerateTextParams($prompt);

$this->assertArrayHasKey('response_format', $params);
$this->assertEquals(['type' => 'json_schema', 'json_schema' => $schema], $params['response_format']);
$this->assertEquals(
[
'type' => 'json_schema',
'json_schema' => [
'name' => 'response_schema',
'schema' => $schema,
],
],
$params['response_format']
);
}

/**
Expand Down Expand Up @@ -950,7 +959,71 @@ public function testPrepareResponseFormatParamWithSchema(): void
$model = $this->createModel();
$format = $model->exposePrepareResponseFormatParam($schema);

$this->assertEquals(['type' => 'json_schema', 'json_schema' => $schema], $format);
$this->assertEquals(
[
'type' => 'json_schema',
'json_schema' => [
'name' => 'response_schema',
'schema' => $schema,
],
],
$format
);
}

/**
* Tests prepareResponseFormatParam() ignores the schema title when naming the envelope.
*
* The OpenAI API requires the json_schema name to match ^[a-zA-Z0-9_-]{1,64}$, so a
* user-supplied title (which may contain spaces or other invalid characters) must not be
* used as the name. A fixed, valid identifier is used instead.
*
* @return void
*/
public function testPrepareResponseFormatParamIgnoresSchemaTitle(): void
{
$schema = [
'title' => 'Review Notes!',
'type' => 'object',
'properties' => ['key' => ['type' => 'string']],
];
$model = $this->createModel();
$format = $model->exposePrepareResponseFormatParam($schema);

$this->assertEquals(
[
'type' => 'json_schema',
'json_schema' => [
'name' => 'response_schema',
'schema' => $schema,
],
],
$format
);
}

/**
* Tests prepareResponseFormatParam() passes through an already-wrapped envelope.
*
* @return void
*/
public function testPrepareResponseFormatParamPassesThroughWrappedEnvelope(): void
{
$envelope = [
'name' => 'classification',
'strict' => true,
'schema' => ['type' => 'object', 'properties' => ['key' => ['type' => 'string']]],
];
$model = $this->createModel();
$format = $model->exposePrepareResponseFormatParam($envelope);

$this->assertEquals(
[
'type' => 'json_schema',
'json_schema' => $envelope,
],
$format
);
}

/**
Expand Down
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