Improve RubyLLM::Chat#with_params (#265) by allowing to override default params

lib/ruby_llm/provider.rb

@@ -14,17 +14,19 @@ def complete(messages, tools:, temperature:, model:, connection:, params: {}, sc
         normalized_temperature = maybe_normalize_temperature(temperature, model)
 
         payload = Utils.deep_merge(
-          params,
           render_payload(
             messages,
             tools: tools,
             temperature: normalized_temperature,
             model: model,
             stream: block_given?,
             schema: schema
-          )
+          ),
+          params
         )
 
+        payload.compact!
+
         if block_given?
           stream_response connection, payload, &
         else

lib/ruby_llm/utils.rb

@@ -24,12 +24,12 @@ def to_safe_array(item)
       end
     end
 
-    def deep_merge(params, payload)
-      params.merge(payload) do |_key, params_value, payload_value|
-        if params_value.is_a?(Hash) && payload_value.is_a?(Hash)
-          deep_merge(params_value, payload_value)
+    def deep_merge(hash1, hash2)
+      hash1.merge(hash2) do |_key, value1, value2|
+        if value1.is_a?(Hash) && value2.is_a?(Hash)
+          deep_merge(value1, value2)
         else
-          payload_value
+          value2
         end
       end
     end

spec/ruby_llm/chat_request_options_spec.rb

@@ -78,6 +78,21 @@
         json_response = JSON.parse('{' + response.content) # rubocop:disable Style/StringConcatenation
         expect(json_response).to eq({ 'result' => 8 })
       end
+
+      it "#{provider}/#{model} can override max_tokens param with a custom value" do # rubocop:disable RSpec/ExampleLength
+        chat = RubyLLM
+               .chat(model: model, provider: provider)
+               .with_params(max_tokens: 2)
+
+        chat.add_message(
+          role: :user,
+          content: 'Always answer with "Once upon a time"'
+        )
+
+        response = chat.complete
+
+        expect(response.content).to eq('Once upon') # Only 2 tokens
+      end
     end
 
     # Providers [:openrouter, :bedrock] supports a {top_k: ...} param to remove low-probability next tokens.