Add core Rerank and RerankResult classes

Author: infinityrobot

lib/ruby_llm/rerank.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module RubyLLM
+  # Core reranking interface. Provides a clean way to generate rerankings
+  # for a given query and set of documents using various provider models.
+  class Rerank
+    attr_reader :results, :model, :search_units
+
+    def initialize(results:, model:, search_units:)
+      @results = results.sort_by { |r| -r.relevance_score }
+      @model = model
+      @search_units = search_units
+    end
+
+    def self.rank(query, # rubocop:disable Metrics/ParameterLists
+                  documents,
+                  model: nil,
+                  provider: nil,
+                  assume_model_exists: false,
+                  context: nil,
+                  top_n: nil,
+                  max_tokens_per_doc: nil)
+      raise ArgumentError, 'No documents provided for reranking' if documents.empty?
+
+      config = context&.config || RubyLLM.config
+      model ||= config.default_rerank_model
+      model, provider = Models.resolve(model, provider: provider, assume_exists: assume_model_exists)
+      model_id = model.id
+
+      provider = Provider.for(model_id) if provider.nil?
+      connection = context ? context.connection_for(provider) : provider.connection(config)
+      provider.rank(query, documents, model: model_id, connection:, top_n:, max_tokens_per_doc:)
+    end
+  end
+end

lib/ruby_llm/rerank_result.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module RubyLLM
+  # Represents a single rerank result with index, relevance score, and document
+  class RerankResult
+    attr_reader :index, :relevance_score, :document
+
+    def initialize(index:, relevance_score:, document:)
+      @index = index
+      @relevance_score = relevance_score
+      @document = document
+    end
+
+    def self.from_hash(hash)
+      new(
+        index: hash[:index],
+        relevance_score: hash[:relevance_score],
+        document: hash[:document]
+      )
+    end
+  end
+end