promptkit/internal/llm/openai_compatible_client_test.go

package llm

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"math"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strconv"
	"strings"
	"testing"
	"time"

	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
)

var errTransportStopped = errors.New("transport stopped after request inspection")

type deadlineCapturingTransport struct {
	deadline    time.Time
	hasDeadline bool
	err         error
}

func (t *deadlineCapturingTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	t.deadline, t.hasDeadline = req.Context().Deadline()
	if t.err != nil {
		return nil, t.err
	}
	return nil, errTransportStopped
}

type contextErrorTransport struct{}

func (contextErrorTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	return nil, req.Context().Err()
}

type roundTripFunc func(*http.Request) (*http.Response, error)

func (f roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
	return f(req)
}

type waitingContextTransport struct{}

func (waitingContextTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	<-req.Context().Done()
	return nil, req.Context().Err()
}

func assertDeadlineNear(t *testing.T, deadline, before, after time.Time, duration time.Duration) {
	t.Helper()

	const tolerance = 100 * time.Millisecond
	earliest := before.Add(duration - tolerance)
	latest := after.Add(duration + tolerance)
	if deadline.Before(earliest) || deadline.After(latest) {
		t.Fatalf("expected deadline between %v and %v, got %v", earliest, latest, deadline)
	}
}

func TestNewOpenAICompatibleClientRejectsInvalidBaseURL(t *testing.T) {
	for _, endpoint := range []string{
		"://invalid",
		"/v1",
		"https:///v1",
		"ftp://provider.example/v1",
		"https://user@provider.example/v1",
		"https://provider.example/v1?mode=chat",
		"https://provider.example/v1#chat",
	} {
		t.Run(endpoint, func(t *testing.T) {
			_, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: endpoint})
			if !errors.Is(err, ErrInvalidConfig) {
				t.Fatalf("expected ErrInvalidConfig, got %v", err)
			}
		})
	}
}

func TestNewOpenAICompatibleClientDoesNotMutateSuppliedZeroTimeoutClient(t *testing.T) {
	transport := http.DefaultTransport
	supplied := &http.Client{Transport: transport}

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		HTTPClient: supplied,
	})
	if err != nil {
		t.Fatalf("unexpected constructor error: %v", err)
	}

	if supplied.Timeout != 0 {
		t.Fatalf("expected supplied client timeout to remain zero, got %v", supplied.Timeout)
	}
	if client.httpClient == supplied {
		t.Fatal("expected constructed client to use a cloned HTTP client")
	}
	if client.httpClient.Timeout <= 0 {
		t.Fatalf("expected constructed client to use a positive default timeout, got %v", client.httpClient.Timeout)
	}
	if client.httpClient.Transport != transport {
		t.Fatal("expected cloned client to preserve the supplied transport")
	}
}

func TestNewOpenAICompatibleClientDoesNotMutateSuppliedNonzeroTimeoutClient(t *testing.T) {
	transport := http.DefaultTransport
	suppliedTimeout := 37 * time.Second
	supplied := &http.Client{
		Timeout:   suppliedTimeout,
		Transport: transport,
	}

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		Timeout:    2 * time.Second,
		HTTPClient: supplied,
	})
	if err != nil {
		t.Fatalf("unexpected constructor error: %v", err)
	}

	if supplied.Timeout != suppliedTimeout {
		t.Fatalf("expected supplied client timeout to remain %v, got %v", suppliedTimeout, supplied.Timeout)
	}
	if client.httpClient == supplied {
		t.Fatal("expected constructed client to use a cloned HTTP client")
	}
	if client.httpClient.Timeout != suppliedTimeout {
		t.Fatalf("expected cloned client timeout %v, got %v", suppliedTimeout, client.httpClient.Timeout)
	}
	if client.httpClient.Transport != transport {
		t.Fatal("expected cloned client to preserve the supplied transport")
	}
}

func TestNewOpenAICompatibleClientTreatsSuppliedNegativeTimeoutAsUnset(t *testing.T) {
	transport := http.DefaultTransport
	supplied := &http.Client{
		Timeout:   -time.Second,
		Transport: transport,
	}
	configuredTimeout := 23 * time.Second

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		Timeout:    configuredTimeout,
		HTTPClient: supplied,
	})
	if err != nil {
		t.Fatalf("unexpected constructor error: %v", err)
	}

	if supplied.Timeout != -time.Second {
		t.Fatalf("expected supplied client timeout to remain negative, got %v", supplied.Timeout)
	}
	if client.httpClient == supplied {
		t.Fatal("expected constructed client to use a cloned HTTP client")
	}
	if client.httpClient.Timeout != configuredTimeout {
		t.Fatalf("expected cloned client timeout %v, got %v", configuredTimeout, client.httpClient.Timeout)
	}
	if client.httpClient.Transport != transport {
		t.Fatal("expected cloned client to preserve the supplied transport")
	}
}

func TestOpenAICompatibleClientGenerateSuccess(t *testing.T) {
	type observedRequest struct {
		Authorization string
		Body          map[string]any
	}
	obs := &observedRequest{}

	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		obs.Authorization = r.Header.Get("Authorization")
		if r.URL.Path != "/v1/chat/completions" {
			t.Fatalf("unexpected path: %s", r.URL.Path)
		}
		if ct := r.Header.Get("Content-Type"); ct != "application/json" {
			t.Fatalf("unexpected content type: %s", ct)
		}

		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&obs.Body); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}

		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{
  "choices": [{"message": {"role": "assistant", "content": "hello from model"}}],
  "usage": {"prompt_tokens": 11, "completion_tokens": 22, "total_tokens": 33}
}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: ts.URL + "/v1",
		Timeout: 2 * time.Second,
	})
	if err != nil {
		t.Fatalf("unexpected constructor error: %v", err)
	}
	t.Setenv("PROMPTKIT_TEST_API_KEY", "secret-key")

	resp, err := client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{
			{Role: "system", Content: "You are helpful."},
			{Role: "user", Content: "Say hello"},
		}},
		Target: domain.ExecutionTarget{
			Model:       "gpt-test",
			Temperature: 0.4,
			MaxTokens:   123,
			TopP:        0.7,
			ServiceTier: "priority",
			APIKeyEnv:   "PROMPTKIT_TEST_API_KEY",
		},
		StructuredOutput: &domain.StructuredOutputSpec{
			Type: domain.StructuredOutputJSONSchema,
			JSONSchema: &domain.StructuredOutputJSONSpec{
				Name:   "weather_schema",
				Strict: true,
				Schema: map[string]any{
					"type": "object",
					"properties": map[string]any{
						"location": map[string]any{"type": "string"},
					},
					"required": []any{"location"},
				},
			},
		},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}

	if resp.Content != "hello from model" {
		t.Fatalf("unexpected content: %q", resp.Content)
	}
	if resp.Usage.PromptTokens != 11 || resp.Usage.CompletionTokens != 22 || resp.Usage.TotalTokens != 33 {
		t.Fatalf("unexpected usage: %+v", resp.Usage)
	}
	if resp.Usage.CachedTokens != 0 || resp.Usage.CacheWriteTokens != 0 {
		t.Fatalf("expected absent cache usage fields to remain zero, got %+v", resp.Usage)
	}

	if obs.Authorization != "Bearer secret-key" {
		t.Fatalf("unexpected Authorization header: %q", obs.Authorization)
	}
	if got, ok := obs.Body["model"].(string); !ok || got != "gpt-test" {
		t.Fatalf("unexpected model payload: %#v", obs.Body["model"])
	}
	if got, ok := obs.Body["temperature"].(float64); !ok || got != 0.4 {
		t.Fatalf("unexpected temperature payload: %#v", obs.Body["temperature"])
	}
	if got, ok := obs.Body["max_tokens"].(float64); !ok || got != 123 {
		t.Fatalf("unexpected max_tokens payload: %#v", obs.Body["max_tokens"])
	}
	if got, ok := obs.Body["top_p"].(float64); !ok || got != 0.7 {
		t.Fatalf("unexpected top_p payload: %#v", obs.Body["top_p"])
	}
	if got, ok := obs.Body["service_tier"].(string); !ok || got != "priority" {
		t.Fatalf("unexpected service_tier payload: %#v", obs.Body["service_tier"])
	}

	msgs, ok := obs.Body["messages"].([]any)
	if !ok || len(msgs) != 2 {
		t.Fatalf("unexpected messages payload: %#v", obs.Body["messages"])
	}
	msg0 := msgs[0].(map[string]any)
	if msg0["role"] != "system" || msg0["content"] != "You are helpful." {
		t.Fatalf("unexpected first message: %#v", msg0)
	}
	msg1 := msgs[1].(map[string]any)
	if msg1["role"] != "user" || msg1["content"] != "Say hello" {
		t.Fatalf("unexpected second message: %#v", msg1)
	}

	responseFormat, ok := obs.Body["response_format"].(map[string]any)
	if !ok {
		t.Fatalf("expected response_format payload, got %#v", obs.Body["response_format"])
	}
	if responseFormat["type"] != "json_schema" {
		t.Fatalf("expected response_format.type=json_schema, got %#v", responseFormat["type"])
	}
	jsonSchema, ok := responseFormat["json_schema"].(map[string]any)
	if !ok {
		t.Fatalf("expected response_format.json_schema map, got %#v", responseFormat["json_schema"])
	}
	if jsonSchema["name"] != "weather_schema" {
		t.Fatalf("expected json_schema.name weather_schema, got %#v", jsonSchema["name"])
	}
	if jsonSchema["strict"] != true {
		t.Fatalf("expected json_schema.strict=true, got %#v", jsonSchema["strict"])
	}
	if _, ok := jsonSchema["schema"].(map[string]any); !ok {
		t.Fatalf("expected json_schema.schema object, got %#v", jsonSchema["schema"])
	}
}

func TestOpenAICompatibleClientDirectAPIKeyPreferredOverEnv(t *testing.T) {
	const directKey = "direct-llm-key"
	t.Setenv("PROMPTKIT_TEST_API_KEY", "env-key")

	var gotAuth string
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		gotAuth = r.Header.Get("Authorization")
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{
			Model:     "model",
			APIKeyEnv: "PROMPTKIT_TEST_API_KEY",
			APIKey:    directKey,
		},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if gotAuth != "Bearer "+directKey {
		t.Fatalf("unexpected Authorization header: %q", gotAuth)
	}
}

func TestOpenAICompatibleClientSerializesCacheControlledMessageAsContentBlock(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{
			{
				Role:    "system",
				Content: "Stable instructions.",
				CacheControl: &domain.CacheControl{
					Type: domain.CacheControlEphemeral,
					TTL:  "1h",
				},
			},
			{Role: "user", Content: "Dynamic request."},
		}},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}

	for _, forbidden := range []string{"cache_control", "extra_params"} {
		if _, exists := observedBody[forbidden]; exists {
			t.Fatalf("expected top-level %s to be omitted, got %#v", forbidden, observedBody[forbidden])
		}
	}

	msgs, ok := observedBody["messages"].([]any)
	if !ok || len(msgs) != 2 {
		t.Fatalf("unexpected messages payload: %#v", observedBody["messages"])
	}
	msg0 := msgs[0].(map[string]any)
	if msg0["role"] != "system" {
		t.Fatalf("unexpected first message role: %#v", msg0["role"])
	}
	contentBlocks, ok := msg0["content"].([]any)
	if !ok || len(contentBlocks) != 1 {
		t.Fatalf("expected first message content block array, got %#v", msg0["content"])
	}
	block := contentBlocks[0].(map[string]any)
	if block["type"] != "text" || block["text"] != "Stable instructions." {
		t.Fatalf("unexpected text content block: %#v", block)
	}
	cacheControl, ok := block["cache_control"].(map[string]any)
	if !ok {
		t.Fatalf("expected cache_control on content block, got %#v", block)
	}
	if cacheControl["type"] != string(domain.CacheControlEphemeral) || cacheControl["ttl"] != "1h" {
		t.Fatalf("unexpected cache_control payload: %#v", cacheControl)
	}

	msg1 := msgs[1].(map[string]any)
	if msg1["role"] != "user" || msg1["content"] != "Dynamic request." {
		t.Fatalf("expected uncached message to keep string content, got %#v", msg1)
	}
}

func TestOpenAICompatibleClientOmitsEmptyCacheControlTTL(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{
			{
				Role:    "system",
				Content: "Stable instructions.",
				CacheControl: &domain.CacheControl{
					Type: domain.CacheControlEphemeral,
				},
			},
		}},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}

	msgs := observedBody["messages"].([]any)
	msg0 := msgs[0].(map[string]any)
	contentBlocks := msg0["content"].([]any)
	block := contentBlocks[0].(map[string]any)
	cacheControl := block["cache_control"].(map[string]any)
	if cacheControl["type"] != string(domain.CacheControlEphemeral) {
		t.Fatalf("unexpected cache_control type: %#v", cacheControl)
	}
	if _, exists := cacheControl["ttl"]; exists {
		t.Fatalf("expected empty ttl to be omitted, got %#v", cacheControl)
	}
}

func TestOpenAICompatibleClientSerializesSessionID(t *testing.T) {
	var observedBody map[string]any
	var observedSessionHeader string
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		observedSessionHeader = r.Header.Get("x-session-id")
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{
			SessionID: " session-123 ",
			Messages:  []domain.RenderedMessage{{Role: "user", Content: "hi"}},
		},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if observedBody["session_id"] != "session-123" {
		t.Fatalf("expected top-level session_id, got %#v", observedBody["session_id"])
	}
	if observedSessionHeader != "" {
		t.Fatalf("did not expect x-session-id header, got %q", observedSessionHeader)
	}
}

func TestOpenAICompatibleClientOmitsEmptySessionID(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{
			SessionID: "   ",
			Messages:  []domain.RenderedMessage{{Role: "user", Content: "hi"}},
		},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if _, exists := observedBody["session_id"]; exists {
		t.Fatalf("expected empty session_id to be omitted, got %#v", observedBody["session_id"])
	}
}

func TestOpenAICompatibleClientRejectsTooLongSessionID(t *testing.T) {
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "model",
	})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{
			SessionID: strings.Repeat("x", domain.SessionIDMaxLength+1),
			Messages:  []domain.RenderedMessage{{Role: "user", Content: "hi"}},
		},
	})
	if err == nil {
		t.Fatal("expected invalid request error")
	}
	if !errors.Is(err, ErrInvalidRequest) {
		t.Fatalf("expected ErrInvalidRequest, got %v", err)
	}
}

func TestOpenAICompatibleClientParsesCacheUsage(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte(`{
  "choices": [{"message": {"role": "assistant", "content": "ok"}}],
  "usage": {
    "prompt_tokens": 100,
    "completion_tokens": 20,
    "total_tokens": 120,
    "prompt_tokens_details": {"cached_tokens": 80},
    "cache_write_tokens": 60
  }
}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1", Model: "model"})
	if err != nil {
		t.Fatal(err)
	}

	resp, err := client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if resp.Usage.PromptTokens != 100 || resp.Usage.CompletionTokens != 20 || resp.Usage.TotalTokens != 120 {
		t.Fatalf("unexpected base usage fields: %+v", resp.Usage)
	}
	if resp.Usage.CachedTokens != 80 || resp.Usage.CacheWriteTokens != 60 {
		t.Fatalf("unexpected cache usage fields: %+v", resp.Usage)
	}
}

func TestOpenAICompatibleClientOmitsResponseFormatWhenNoStructuredOutput(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if _, exists := observedBody["response_format"]; exists {
		t.Fatalf("expected response_format omitted, got %#v", observedBody["response_format"])
	}
	if _, exists := observedBody["service_tier"]; exists {
		t.Fatalf("expected service_tier omitted, got %#v", observedBody["service_tier"])
	}
}

func TestOpenAICompatibleClientSerializesReasoningEffortAndExtraParams(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{
			Model:           "model",
			ReasoningEffort: "high",
			ExtraParams: map[string]any{
				"string_value":  "on",
				"number_value":  42,
				"boolean_value": true,
				"object_value":  map[string]any{"nested": "value", "count": 2},
				"array_value":   []any{"first", 3, false},
			},
		},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if observedBody["reasoning_effort"] != "high" {
		t.Fatalf("expected reasoning_effort high, got %#v", observedBody["reasoning_effort"])
	}
	if observedBody["string_value"] != "on" {
		t.Fatalf("unexpected string extra param: %#v", observedBody["string_value"])
	}
	if observedBody["number_value"] != float64(42) {
		t.Fatalf("unexpected number extra param: %#v", observedBody["number_value"])
	}
	if observedBody["boolean_value"] != true {
		t.Fatalf("unexpected boolean extra param: %#v", observedBody["boolean_value"])
	}
	objectValue, ok := observedBody["object_value"].(map[string]any)
	if !ok || objectValue["nested"] != "value" || objectValue["count"] != float64(2) {
		t.Fatalf("unexpected object extra param: %#v", observedBody["object_value"])
	}
	if _, exists := observedBody["extra_params"]; exists {
		t.Fatalf("expected extra_params wrapper omitted, got %#v", observedBody["extra_params"])
	}
	arrayValue, ok := observedBody["array_value"].([]any)
	if !ok || len(arrayValue) != 3 || arrayValue[0] != "first" || arrayValue[1] != float64(3) || arrayValue[2] != false {
		t.Fatalf("unexpected array extra param: %#v", observedBody["array_value"])
	}
}

func TestOpenAICompatibleClientOmitsReasoningEffortWhenUnset(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if _, exists := observedBody["reasoning_effort"]; exists {
		t.Fatalf("expected reasoning_effort omitted, got %#v", observedBody["reasoning_effort"])
	}
	if _, exists := observedBody["extra_params"]; exists {
		t.Fatalf("expected extra_params wrapper omitted, got %#v", observedBody["extra_params"])
	}
}

func TestOpenAICompatibleClientSerializesExplicitZeroNumericOverrides(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Model: "model"},
		TargetPresence: domain.ExecutionTargetPresence{
			Temperature: true,
			MaxTokens:   true,
			TopP:        true,
		},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if observedBody["temperature"] != float64(0) {
		t.Fatalf("expected explicit zero temperature, got %#v", observedBody["temperature"])
	}
	if observedBody["max_tokens"] != float64(0) {
		t.Fatalf("expected explicit zero max_tokens, got %#v", observedBody["max_tokens"])
	}
	if observedBody["top_p"] != float64(0) {
		t.Fatalf("expected explicit zero top_p, got %#v", observedBody["top_p"])
	}
}

func TestOpenAICompatibleClientOmitsImplicitZeroNumericFields(t *testing.T) {
	var observedBody map[string]any
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		if err := json.NewDecoder(r.Body).Decode(&observedBody); err != nil {
			t.Fatalf("failed to decode request body: %v", err)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	for _, field := range []string{"temperature", "max_tokens", "top_p"} {
		if _, exists := observedBody[field]; exists {
			t.Fatalf("expected implicit zero field %q to be omitted, got body %#v", field, observedBody)
		}
	}
}

func TestOpenAICompatibleClientOmittedTimeoutUsesClientTimeout(t *testing.T) {
	transport := &deadlineCapturingTransport{}
	clientTimeout := 5 * time.Second

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Timeout: clientTimeout,
		HTTPClient: &http.Client{
			Transport: transport,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	before := time.Now()
	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Model: "model", TimeoutSeconds: 0},
	})
	after := time.Now()
	if err == nil {
		t.Fatal("expected transport error")
	}
	if !errors.Is(err, ErrRequestFailed) {
		t.Fatalf("expected ErrRequestFailed, got %v", err)
	}
	if !errors.Is(err, errTransportStopped) {
		t.Fatalf("expected transport cause, got %v", err)
	}
	if !transport.hasDeadline {
		t.Fatal("expected client timeout to set a transport deadline")
	}
	assertDeadlineNear(t, transport.deadline, before, after, clientTimeout)
}

func TestOpenAICompatibleClientRejectsInvalidExtraParamsBeforeProviderCall(t *testing.T) {
	tests := []struct {
		name        string
		extraParams map[string]any
		want        string
	}{
		{name: "empty key", extraParams: map[string]any{"": "empty"}, want: "key must not be empty"},
		{name: "unserializable value", extraParams: map[string]any{"bad": math.Inf(1)}, want: "JSON-serializable"},
	}
	for _, key := range []string{
		"model",
		"session_id",
		"messages",
		"temperature",
		"max_tokens",
		"top_p",
		"service_tier",
		"reasoning_effort",
		"response_format",
	} {
		tests = append(tests, struct {
			name        string
			extraParams map[string]any
			want        string
		}{
			name:        "reserved key " + key,
			extraParams: map[string]any{key: "collision"},
			want:        "reserved request field",
		})
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			called := false
			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				called = true
				_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
			}))
			defer ts.Close()

			client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
			if err != nil {
				t.Fatal(err)
			}

			_, err = client.Generate(context.Background(), domain.GenerateRequest{
				Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
				Target: domain.ExecutionTarget{Model: "model", ExtraParams: tc.extraParams},
			})
			if err == nil {
				t.Fatal("expected invalid request error")
			}
			if !errors.Is(err, ErrInvalidRequest) {
				t.Fatalf("expected ErrInvalidRequest, got %v", err)
			}
			if !strings.Contains(err.Error(), tc.want) {
				t.Fatalf("expected error to contain %q, got %v", tc.want, err)
			}
			if called {
				t.Fatal("provider should not be called for invalid extra_params")
			}
		})
	}
}

func TestOpenAICompatibleClientNoAuthorizationHeaderWhenNoAPIKey(t *testing.T) {
	hadAuth := false
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		hadAuth = r.Header.Get("Authorization") != ""
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Model: "model"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if hadAuth {
		t.Fatal("did not expect Authorization header")
	}
}

func TestOpenAICompatibleClientAPIKeyEnvMissing(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1", Model: "model"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{APIKeyEnv: "PROMPTKIT_MISSING_KEY"},
	})
	if err == nil {
		t.Fatal("expected missing API key env error")
	}
	if !errors.Is(err, ErrInvalidRequest) {
		t.Fatalf("expected ErrInvalidRequest, got %v", err)
	}
}

func TestOpenAICompatibleClientModelFallbackFromConfig(t *testing.T) {
	gotModel := ""
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var body map[string]any
		_ = json.NewDecoder(r.Body).Decode(&body)
		if m, ok := body["model"].(string); ok {
			gotModel = m
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"ok"}}]}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1", Model: "default-model"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if gotModel != "default-model" {
		t.Fatalf("expected default model, got %q", gotModel)
	}
}

func TestOpenAICompatibleClientEndpointOverride(t *testing.T) {
	defaultHit := false
	overrideHit := false

	defaultServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defaultHit = true
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"default"}}]}`))
	}))
	defer defaultServer.Close()

	overrideServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		overrideHit = true
		if r.URL.Path != "/v1/chat/completions" {
			t.Fatalf("unexpected path: %s", r.URL.Path)
		}
		_, _ = w.Write([]byte(`{"choices":[{"message":{"content":"override"}}]}`))
	}))
	defer overrideServer.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: defaultServer.URL + "/v1", Model: "m"})
	if err != nil {
		t.Fatal(err)
	}

	resp, err := client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Endpoint: overrideServer.URL + "/v1"},
	})
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if resp.Content != "override" {
		t.Fatalf("expected override response, got %q", resp.Content)
	}
	if defaultHit {
		t.Fatal("default endpoint should not have been called")
	}
	if !overrideHit {
		t.Fatal("override endpoint should have been called")
	}
}

func TestOpenAICompatibleClientNon2xxError(t *testing.T) {
	const sensitiveBody = `provider-secret-fragment request_payload_details`
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusBadRequest)
		_, _ = w.Write([]byte(`{"error":"` + sensitiveBody + `"}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1", Model: "m"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if err == nil {
		t.Fatal("expected non-2xx error")
	}
	if !errors.Is(err, ErrUnexpectedStatus) {
		t.Fatalf("expected ErrUnexpectedStatus, got %v", err)
	}
	if !strings.Contains(err.Error(), "status=400") {
		t.Fatalf("expected status detail, got %v", err)
	}
	if strings.Contains(err.Error(), sensitiveBody) {
		t.Fatalf("expected provider response body to be redacted, got %v", err)
	}
}

func TestOpenAICompatibleClientMalformedResponseInvalidJSON(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte(`{not valid json`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1", Model: "m"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if err == nil {
		t.Fatal("expected malformed response error")
	}
	if !errors.Is(err, ErrMalformedResponse) {
		t.Fatalf("expected ErrMalformedResponse, got %v", err)
	}
}

func TestOpenAICompatibleClientMalformedResponseMissingChoices(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte(`{"choices": []}`))
	}))
	defer ts.Close()

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{BaseURL: ts.URL + "/v1", Model: "m"})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if err == nil {
		t.Fatal("expected malformed response error")
	}
	if !errors.Is(err, ErrMalformedResponse) {
		t.Fatalf("expected ErrMalformedResponse, got %v", err)
	}
}

func TestOpenAICompatibleClientGenerationTimeoutSetsEarlierDeadline(t *testing.T) {
	transport := &deadlineCapturingTransport{err: context.DeadlineExceeded}
	generationTimeout := 2 * time.Second

	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "m",
		HTTPClient: &http.Client{
			Timeout:   10 * time.Second,
			Transport: transport,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	before := time.Now()
	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{
			TimeoutSeconds: int(generationTimeout / time.Second),
		},
	})
	after := time.Now()
	if err == nil {
		t.Fatal("expected transport error")
	}
	if !errors.Is(err, ErrRequestFailed) {
		t.Fatalf("expected ErrRequestFailed, got %v", err)
	}
	if !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("expected generation deadline identity, got %v", err)
	}
	if !transport.hasDeadline {
		t.Fatal("expected generation timeout to set a transport deadline")
	}
	assertDeadlineNear(t, transport.deadline, before, after, generationTimeout)
}

func TestOpenAICompatibleClientCallerDeadlineTakesPrecedence(t *testing.T) {
	transport := &deadlineCapturingTransport{err: context.DeadlineExceeded}
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "m",
		HTTPClient: &http.Client{
			Timeout:   10 * time.Second,
			Transport: transport,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	callerDeadline := time.Now().Add(time.Second)
	ctx, cancel := context.WithDeadline(context.Background(), callerDeadline)
	defer cancel()

	_, err = client.Generate(ctx, domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{
			TimeoutSeconds: 2,
		},
	})
	if err == nil {
		t.Fatal("expected transport error")
	}
	if !errors.Is(err, ErrRequestFailed) {
		t.Fatalf("expected ErrRequestFailed, got %v", err)
	}
	if !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("expected caller deadline identity, got %v", err)
	}
	if !transport.hasDeadline {
		t.Fatal("expected caller context to set a transport deadline")
	}
	if !transport.deadline.Equal(callerDeadline) {
		t.Fatalf("expected caller deadline %v, got %v", callerDeadline, transport.deadline)
	}
}

func TestOpenAICompatibleClientCancellationReturnsRequestFailure(t *testing.T) {
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "m",
		HTTPClient: &http.Client{
			Transport: contextErrorTransport{},
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	ctx, cancel := context.WithCancel(context.Background())
	cancel()

	_, err = client.Generate(ctx, domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if err == nil {
		t.Fatal("expected cancellation error")
	}
	if !errors.Is(err, ErrRequestFailed) {
		t.Fatalf("expected ErrRequestFailed, got %v", err)
	}
	if !errors.Is(err, context.Canceled) {
		t.Fatalf("expected cancellation identity, got %v", err)
	}
}

func TestOpenAICompatibleClientExpiredCallerDeadlineReturnsRequestFailure(t *testing.T) {
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "m",
		HTTPClient: &http.Client{
			Transport: contextErrorTransport{},
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	ctx, cancel := context.WithDeadline(context.Background(), time.Unix(1, 0))
	defer cancel()
	_, err = client.Generate(ctx, domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if !errors.Is(err, ErrRequestFailed) || !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("expected request failure and caller deadline identities, got %v", err)
	}
}

func TestOpenAICompatibleClientWholeRequestTimeoutReturnsRequestFailure(t *testing.T) {
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "m",
		HTTPClient: &http.Client{
			Timeout:   time.Millisecond,
			Transport: waitingContextTransport{},
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
	})
	if !errors.Is(err, ErrRequestFailed) || !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("expected request failure and client timeout identities, got %v", err)
	}
}

func TestOpenAICompatibleClientTransportFailurePreservesCauseWithoutSensitiveText(t *testing.T) {
	transportCause := errors.New("transport diagnostic")
	const (
		endpoint = "http://sensitive-endpoint.example/private"
		apiKey   = "sensitive-api-key"
		content  = "sensitive prompt content"
	)
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: endpoint,
		Model:   "m",
		HTTPClient: &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
			return nil, transportCause
		})},
	})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: content}}},
		Target: domain.ExecutionTarget{APIKey: apiKey},
	})
	if !errors.Is(err, ErrRequestFailed) || !errors.Is(err, transportCause) {
		t.Fatalf("expected request failure and transport cause identities, got %v", err)
	}
	var requestErr *url.Error
	if !errors.As(err, &requestErr) {
		t.Fatalf("expected underlying http.Client.Do URL error, got %T: %v", err, err)
	}
	for _, sensitive := range []string{endpoint, "sensitive-endpoint.example", apiKey, content, transportCause.Error()} {
		if strings.Contains(err.Error(), sensitive) {
			t.Fatalf("transport error exposed %q: %v", sensitive, err)
		}
	}
}

func TestOpenAICompatibleClientRejectsInvalidExecutionSettings(t *testing.T) {
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "http://example.com/v1",
		Model:   "m",
	})
	if err != nil {
		t.Fatal(err)
	}

	type testCase struct {
		name   string
		target domain.ExecutionTarget
	}
	tests := []testCase{
		{name: "non-finite temperature", target: domain.ExecutionTarget{Temperature: math.NaN()}},
		{name: "negative max tokens", target: domain.ExecutionTarget{MaxTokens: -1}},
		{name: "non-finite top p", target: domain.ExecutionTarget{TopP: math.Inf(1)}},
		{name: "negative timeout", target: domain.ExecutionTarget{TimeoutSeconds: -1}},
	}
	if strconv.IntSize == 64 {
		durationLimit := int64(math.MaxInt64 / int64(time.Second))
		tests = append(tests, testCase{name: "unrepresentable timeout", target: domain.ExecutionTarget{TimeoutSeconds: int(durationLimit) + 1}})
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			_, err := client.Generate(context.Background(), domain.GenerateRequest{
				Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
				Target: tt.target,
			})
			if err == nil {
				t.Fatal("expected invalid request error")
			}
			if !errors.Is(err, ErrInvalidRequest) {
				t.Fatalf("expected ErrInvalidRequest, got %v", err)
			}
		})
	}
}

func TestOpenAICompatibleClientAllowsEmptyConfiguredBaseURL(t *testing.T) {
	var selectedURL string
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "",
		Model:   "m",
		HTTPClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
			selectedURL = req.URL.String()
			return &http.Response{
				StatusCode: http.StatusOK,
				Header:     make(http.Header),
				Body: io.NopCloser(strings.NewReader(
					`{"choices":[{"message":{"content":"request endpoint"}}]}`,
				)),
				Request: req,
			}, nil
		})},
	})
	if err != nil {
		t.Fatalf("expected empty configured base URL to be allowed, got %v", err)
	}

	response, err := client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{Endpoint: "http://request-endpoint.example/v1"},
	})
	if err != nil {
		t.Fatalf("generate with request endpoint: %v", err)
	}
	if response.Content != "request endpoint" {
		t.Fatalf("response content = %q, want request endpoint", response.Content)
	}
	if selectedURL != "http://request-endpoint.example/v1/chat/completions" {
		t.Fatalf("selected URL = %q", selectedURL)
	}
}

func TestOpenAICompatibleClientComposesCompletionURL(t *testing.T) {
	tests := []struct {
		name    string
		baseURL string
		wantURL string
	}{
		{name: "HTTP host", baseURL: "http://provider.example", wantURL: "http://provider.example/chat/completions"},
		{name: "HTTPS host", baseURL: "https://provider.example", wantURL: "https://provider.example/chat/completions"},
		{name: "nested path", baseURL: "https://provider.example/api/openai/v1", wantURL: "https://provider.example/api/openai/v1/chat/completions"},
		{name: "trailing slash", baseURL: "https://provider.example/v1/", wantURL: "https://provider.example/v1/chat/completions"},
		{name: "repeated trailing slashes", baseURL: "  https://provider.example/api/v1///  ", wantURL: "https://provider.example/api/v1/chat/completions"},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			var selectedURL string
			client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
				BaseURL: tc.baseURL,
				Model:   "m",
				HTTPClient: &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
					selectedURL = req.URL.String()
					return &http.Response{
						StatusCode: http.StatusOK,
						Header:     make(http.Header),
						Body:       io.NopCloser(strings.NewReader(`{"choices":[{"message":{"content":"ok"}}]}`)),
						Request:    req,
					}, nil
				})},
			})
			if err != nil {
				t.Fatalf("construct client: %v", err)
			}

			_, err = client.Generate(context.Background(), domain.GenerateRequest{
				Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
			})
			if err != nil {
				t.Fatalf("generate: %v", err)
			}
			if selectedURL != tc.wantURL {
				t.Fatalf("selected URL = %q, want %q", selectedURL, tc.wantURL)
			}
		})
	}
}

func TestOpenAICompatibleClientRejectsInvalidSelectedEndpointBeforeTransport(t *testing.T) {
	invalidEndpoints := []string{
		"/v1",
		"https:///v1",
		"ftp://provider.example/v1",
		"https://user@provider.example/v1",
		"https://provider.example/v1?mode=chat",
		"https://provider.example/v1#chat",
		"https://sensitive-endpoint.example/%zz",
	}
	for _, endpoint := range invalidEndpoints {
		t.Run(endpoint, func(t *testing.T) {
			transportCalls := 0
			client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
				BaseURL: "https://configured.example/v1",
				Model:   "m",
				HTTPClient: &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
					transportCalls++
					return nil, errors.New("transport must not be called")
				})},
			})
			if err != nil {
				t.Fatalf("construct client: %v", err)
			}

			_, err = client.Generate(context.Background(), domain.GenerateRequest{
				Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
				Target: domain.ExecutionTarget{Endpoint: endpoint},
			})
			if !errors.Is(err, ErrInvalidRequest) {
				t.Fatalf("expected ErrInvalidRequest, got %v", err)
			}
			if strings.Contains(err.Error(), endpoint) {
				t.Fatalf("error exposed selected endpoint %q: %v", endpoint, err)
			}
			if transportCalls != 0 {
				t.Fatalf("transport calls = %d, want 0", transportCalls)
			}
		})
	}
}

func TestOpenAICompatibleClientRequiresEndpointWhenUnsetEverywhere(t *testing.T) {
	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
		BaseURL: "",
		Model:   "m",
	})
	if err != nil {
		t.Fatal(err)
	}

	_, err = client.Generate(context.Background(), domain.GenerateRequest{
		Prompt: domain.RenderedPrompt{Messages: []domain.RenderedMessage{{Role: "user", Content: "hi"}}},
		Target: domain.ExecutionTarget{},
	})
	if err == nil {
		t.Fatal("expected endpoint-required error")
	}
	if !errors.Is(err, ErrInvalidRequest) {
		t.Fatalf("expected ErrInvalidRequest, got %v", err)
	}
}