Retrieval and Agents

Combine Sigmie retrieval and reranking with text generation in RAG workflows — search, rerank, then call your LLM client of choice from app code.

On this page

Sigmie is a retrieval and indexing library. It gives you:

  • Indices and mappings.
  • Keyword and semantic search.
  • Reranking on search responses.
  • Embeddings as a first-class field type.

It does not ship:

  • An LLM client.
  • A prompt builder.
  • A RAG orchestrator (no single “search → context → model → answer” API).

For text generation, use your preferred HTTP client, vendor SDK, or framework. The application code below shows the pattern.

What stays in Sigmie

Area Sigmie API
Retrieval newSearch(), newMultiSearch(), newQuery(), newRecommend()
Reranking $response->rerank(...) with a registered RerankApi
Embeddings EmbeddingsApi + ->semantic() on text fields
Taxonomy tags Optional Magic Tags package

The pattern: retrieve, rerank, generate

use Sigmie\AI\APIs\OpenAIEmbeddingsApi;
use Sigmie\AI\APIs\CohereRerankApi;
 
$sigmie->registerApi('embeddings', new OpenAIEmbeddingsApi('sk-...'));
$sigmie->registerApi('reranker', new CohereRerankApi('co-...'));
 
// 1. Retrieve.
$response = $sigmie->newSearch('docs')
    ->properties($props)
    ->semantic()
    ->queryString('What is your return policy?')
    ->size(20)
    ->get();
 
// 2. Rerank.
$top5 = $response->rerank('reranker', ['content'], topK: 5);
 
// 3. Generate (your code, not Sigmie's).
$context = collect($top5)->pluck('_source.content')->implode("\n\n");
 
$answer = $yourOpenAiClient->chat([
    ['role' => 'system', 'content' => 'Answer using only the provided context.'],
    ['role' => 'user', 'content' => "Context:\n{$context}\n\nQuestion: What is your return policy?"],
]);

Reranking

$response->rerank() accepts either a registered API name or a concrete RerankApi:

$response->rerank('reranker', ['content']);
$response->rerank('reranker', ['title', 'content'], topK: 3);
$response->rerank('reranker', ['content'], 'return policy');

The signature is:

rerank(
    RerankApi|string $reranker,
    array $fields,
    ?string $query = null,        // defaults to the search's query string
    ?int $topK = null,            // defaults to the search's size
): array;

For advanced cases, build a rerank manually with Sigmie\Search\NewRerank.

Optional: conversation history

Sigmie\AI\History\Index is a standalone index for storing conversation turns. It uses embeddings for semantic recall, but stays decoupled from generation — your app reads from it before composing each prompt.

See also