fix(http): preserve custom finch in sync requests

lib/req_llm/provider/defaults.ex

@@ -567,12 +567,11 @@ defmodule ReqLLM.Provider.Defaults do
     |> Req.Request.put_header("authorization", "Bearer #{api_key}")
     |> Req.Request.register_options(extra_option_keys)
     |> Req.Request.merge_options(
-      [
-        finch: ReqLLM.Application.finch_name(),
-        model: model.provider_model_id || model.id,
-        auth: {:bearer, api_key}
-      ] ++
-        user_opts
+      finch_option(request) ++
+        [
+          model: model.provider_model_id || model.id,
+          auth: {:bearer, api_key}
+        ] ++ user_opts
     )
     |> ReqLLM.Step.Retry.attach()
     |> ReqLLM.Step.Error.attach()
@@ -583,6 +582,11 @@ defmodule ReqLLM.Provider.Defaults do
     |> ReqLLM.Step.Fixture.maybe_attach(model, user_opts)
   end
 
+  @spec finch_option(Req.Request.t()) :: keyword()
+  def finch_option(%Req.Request{} = request) do
+    [finch: request.options[:finch] || ReqLLM.Application.finch_name()]
+  end
+
   @doc """
   Fetches API key and extra common option keys.
   """

lib/req_llm/providers/anthropic.ex

@@ -316,7 +316,8 @@ defmodule ReqLLM.Providers.Anthropic do
     |> Req.Request.put_private(:req_llm_model, model)
     |> maybe_add_beta_header(user_opts)
     |> Req.Request.merge_options(
-      [finch: ReqLLM.Application.finch_name(), model: get_api_model_id(model)] ++ user_opts
+      ReqLLM.Provider.Defaults.finch_option(request) ++
+        [model: get_api_model_id(model)] ++ user_opts
     )
     |> ReqLLM.Step.Error.attach()
     |> ReqLLM.Step.Retry.attach(user_opts)

lib/req_llm/providers/azure.ex

@@ -542,7 +542,7 @@ defmodule ReqLLM.Providers.Azure do
       end)
     end)
     |> Req.Request.register_options(registered_option_keys)
-    |> Req.Request.merge_options([finch: ReqLLM.Application.finch_name()] ++ user_opts)
+    |> Req.Request.merge_options(ReqLLM.Provider.Defaults.finch_option(request) ++ user_opts)
     |> ReqLLM.Step.Retry.attach()
     |> ReqLLM.Step.Error.attach()
     |> Req.Request.append_response_steps(llm_decode_response: &decode_response/1)

lib/req_llm/providers/cohere.ex

@@ -79,12 +79,11 @@ defmodule ReqLLM.Providers.Cohere do
     |> Req.Request.put_header("authorization", "Bearer #{api_key}")
     |> Req.Request.register_options(extra_option_keys)
     |> Req.Request.merge_options(
-      [
-        finch: ReqLLM.Application.finch_name(),
-        model: model.provider_model_id || model.id,
-        auth: {:bearer, api_key}
-      ] ++
-        user_opts
+      ReqLLM.Provider.Defaults.finch_option(request) ++
+        [
+          model: model.provider_model_id || model.id,
+          auth: {:bearer, api_key}
+        ] ++ user_opts
     )
     |> ReqLLM.Step.Retry.attach()
     |> ReqLLM.Step.Error.attach()

lib/req_llm/providers/google_vertex.ex

@@ -349,7 +349,7 @@ defmodule ReqLLM.Providers.GoogleVertex do
     gcp_creds = Req.Request.get_private(request, :gcp_credentials)
 
     request
-    |> Req.Request.merge_options(finch: ReqLLM.Application.finch_name())
+    |> Req.Request.merge_options(ReqLLM.Provider.Defaults.finch_option(request))
     |> ReqLLM.Step.Error.attach()
     |> ReqLLM.Step.Retry.attach()
     |> Req.Request.append_response_steps(llm_decode_response: &decode_response/1)
@@ -381,7 +381,7 @@ defmodule ReqLLM.Providers.GoogleVertex do
 
   defp attach_ocr(request, model, gcp_creds, opts) do
     request
-    |> Req.Request.merge_options(finch: ReqLLM.Application.finch_name())
+    |> Req.Request.merge_options(ReqLLM.Provider.Defaults.finch_option(request))
     |> ReqLLM.Step.Error.attach()
     |> ReqLLM.Step.Retry.attach()
     |> ReqLLM.Step.Fixture.maybe_attach(model, opts)
@@ -390,7 +390,7 @@ defmodule ReqLLM.Providers.GoogleVertex do
 
   defp attach_embedding(request, model, gcp_creds, opts) do
     request
-    |> Req.Request.merge_options(finch: ReqLLM.Application.finch_name())
+    |> Req.Request.merge_options(ReqLLM.Provider.Defaults.finch_option(request))
     |> ReqLLM.Step.Error.attach()
     |> ReqLLM.Step.Retry.attach()
     |> ReqLLM.Step.Usage.attach(model)

lib/req_llm/providers/openai.ex

@@ -661,12 +661,10 @@ defmodule ReqLLM.Providers.OpenAI do
     |> maybe_put_authorization_header(credential)
     |> Req.Request.register_options(extra_option_keys)
     |> Req.Request.merge_options(
-      [
-        finch: ReqLLM.Application.finch_name(),
-        model: model.provider_model_id || model.id
-      ] ++
-        auth_req_options(credential) ++
-        user_opts
+      ReqLLM.Provider.Defaults.finch_option(request) ++
+        [
+          model: model.provider_model_id || model.id
+        ] ++ auth_req_options(credential) ++ user_opts
     )
     |> ReqLLM.Step.Retry.attach()
     |> ReqLLM.Step.Error.attach()

lib/req_llm/providers/openai_codex.ex

@@ -186,11 +186,11 @@ defmodule ReqLLM.Providers.OpenAICodex do
     |> Req.Request.put_header("originator", originator)
     |> Req.Request.register_options(extra_option_keys)
     |> Req.Request.merge_options(
-      [
-        finch: ReqLLM.Application.finch_name(),
-        model: model.provider_model_id || model.id,
-        auth: {:bearer, credential.token}
-      ] ++ user_opts
+      ReqLLM.Provider.Defaults.finch_option(request) ++
+        [
+          model: model.provider_model_id || model.id,
+          auth: {:bearer, credential.token}
+        ] ++ user_opts
     )
     |> attach_retry(user_opts)
     |> ReqLLM.Step.Error.attach()

test/provider/azure/azure_test.exs

@@ -79,6 +79,21 @@ defmodule ReqLLM.Providers.AzureTest do
       assert url_string =~ "api-version=2023-05-15"
     end
 
+    test "preserves custom finch from req_http_options" do
+      {:ok, model} = ReqLLM.model("azure:gpt-4o")
+
+      {:ok, request} =
+        Azure.prepare_request(
+          :chat,
+          model,
+          "Hello",
+          base_url: "https://my-resource.openai.azure.com/openai",
+          req_http_options: [finch: :custom_finch]
+        )
+
+      assert request.options[:finch] == :custom_finch
+    end
+
     test "embedding operation uses correct endpoint" do
       model = %LLMDB.Model{
         id: "text-embedding-3-small",

test/providers/openai_test.exs

@@ -75,6 +75,16 @@ defmodule ReqLLM.Providers.OpenAITest do
       assert request.method == :post
     end
 
+    test "prepare_request preserves custom finch from req_http_options" do
+      {:ok, model} = ReqLLM.model("openai:gpt-4-turbo")
+      context = context_fixture()
+
+      {:ok, request} =
+        OpenAI.prepare_request(:chat, model, context, req_http_options: [finch: :custom_finch])
+
+      assert request.options[:finch] == :custom_finch
+    end
+
     test "prepare_request routes gpt-4o models to Responses API" do
       {:ok, model} = ReqLLM.model("openai:gpt-4o")
       context = context_fixture()

test/req_llm/step/retry_test.exs

@@ -103,6 +103,20 @@ defmodule ReqLLM.Step.RetryTest do
       refute request.options[:retry_delay]
     end
 
+    test "default_attach preserves an existing finch option" do
+      {:ok, model} = ReqLLM.model("openai:gpt-4")
+
+      request =
+        ReqLLM.Provider.Defaults.default_attach(
+          ReqLLM.Providers.OpenAI,
+          Req.new(finch: :custom_finch),
+          model,
+          api_key: "test-key"
+        )
+
+      assert request.options[:finch] == :custom_finch
+    end
+
     test "retry function correctly identifies retryable errors" do
       {:ok, model} = ReqLLM.model("openai:gpt-4")