feat(ingestion): add OpenAI-compatible LLM HTTP client with 429 retry

ingestion/internal/llm/client_test.go

@@ -0,0 +1,86 @@
+package llm
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func mockServer(t *testing.T, response string) *httptest.Server {
+	t.Helper()
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, "/chat/completions", r.URL.Path)
+		assert.Equal(t, "application/json", r.Header.Get("Content-Type"))
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]any{
+			"choices": []map[string]any{
+				{"message": map[string]any{"role": "assistant", "content": response}},
+			},
+		})
+	}))
+}
+
+func TestClient_Complete(t *testing.T) {
+	srv := mockServer(t, "hello world")
+	defer srv.Close()
+
+	c := New(srv.URL, "", "test-model", 10*time.Second)
+	got, err := c.Complete(context.Background(), "you are helpful", "say hello")
+	require.NoError(t, err)
+	assert.Equal(t, "hello world", got)
+}
+
+func TestClient_ReturnsErrorOnNon200(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "overloaded", http.StatusServiceUnavailable)
+	}))
+	defer srv.Close()
+
+	c := New(srv.URL, "", "test-model", 10*time.Second)
+	_, err := c.Complete(context.Background(), "sys", "user")
+	assert.Error(t, err)
+}
+
+func TestClient_SendsAuthHeader(t *testing.T) {
+	var gotAuth string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotAuth = r.Header.Get("Authorization")
+		json.NewEncoder(w).Encode(map[string]any{
+			"choices": []map[string]any{{"message": map[string]any{"content": "ok"}}},
+		})
+	}))
+	defer srv.Close()
+
+	c := New(srv.URL, "my-key", "test-model", 10*time.Second)
+	_, err := c.Complete(context.Background(), "sys", "user")
+	require.NoError(t, err)
+	assert.Equal(t, "Bearer my-key", gotAuth)
+}
+
+func TestClient_Retries429(t *testing.T) {
+	calls := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls++
+		if calls == 1 {
+			w.Header().Set("Retry-After", "0")
+			w.WriteHeader(http.StatusTooManyRequests)
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]any{
+			"choices": []map[string]any{{"message": map[string]any{"content": "retried"}}},
+		})
+	}))
+	defer srv.Close()
+
+	c := New(srv.URL, "", "test-model", 10*time.Second)
+	got, err := c.Complete(context.Background(), "sys", "user")
+	require.NoError(t, err)
+	assert.Equal(t, "retried", got)
+	assert.Equal(t, 2, calls)
+}