feat: integrate CheckErrorPolicy into Gemini error handling paths

backend/internal/service/gemini_error_policy_test.go

+//go:build unit
+
+package service
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+)
+
+// ---------------------------------------------------------------------------
+// TestShouldFailoverGeminiUpstreamError — verifies the failover decision
+// for the ErrorPolicyNone path (original logic preserved).
+// ---------------------------------------------------------------------------
+
+func TestShouldFailoverGeminiUpstreamError(t *testing.T) {
+	svc := &GeminiMessagesCompatService{}
+
+	tests := []struct {
+		name       string
+		statusCode int
+		expected   bool
+	}{
+		{"401_failover", 401, true},
+		{"403_failover", 403, true},
+		{"429_failover", 429, true},
+		{"529_failover", 529, true},
+		{"500_failover", 500, true},
+		{"502_failover", 502, true},
+		{"503_failover", 503, true},
+		{"400_no_failover", 400, false},
+		{"404_no_failover", 404, false},
+		{"422_no_failover", 422, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := svc.shouldFailoverGeminiUpstreamError(tt.statusCode)
+			require.Equal(t, tt.expected, got)
+		})
+	}
+}
+
+// ---------------------------------------------------------------------------
+// TestCheckErrorPolicy_GeminiAccounts — verifies CheckErrorPolicy works
+// correctly for Gemini platform accounts (API Key type).
+// ---------------------------------------------------------------------------
+
+func TestCheckErrorPolicy_GeminiAccounts(t *testing.T) {
+	tests := []struct {
+		name       string
+		account    *Account
+		statusCode int
+		body       []byte
+		expected   ErrorPolicyResult
+	}{
+		{
+			name: "gemini_apikey_custom_codes_hit",
+			account: &Account{
+				ID:       100,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"custom_error_codes_enabled": true,
+					"custom_error_codes":         []any{float64(429), float64(500)},
+				},
+			},
+			statusCode: 429,
+			body:       []byte(`{"error":"rate limited"}`),
+			expected:   ErrorPolicyMatched,
+		},
+		{
+			name: "gemini_apikey_custom_codes_miss",
+			account: &Account{
+				ID:       101,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"custom_error_codes_enabled": true,
+					"custom_error_codes":         []any{float64(429)},
+				},
+			},
+			statusCode: 500,
+			body:       []byte(`{"error":"internal"}`),
+			expected:   ErrorPolicySkipped,
+		},
+		{
+			name: "gemini_apikey_no_custom_codes_returns_none",
+			account: &Account{
+				ID:       102,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+			},
+			statusCode: 500,
+			body:       []byte(`{"error":"internal"}`),
+			expected:   ErrorPolicyNone,
+		},
+		{
+			name: "gemini_apikey_temp_unschedulable_hit",
+			account: &Account{
+				ID:       103,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"temp_unschedulable_enabled": true,
+					"temp_unschedulable_rules": []any{
+						map[string]any{
+							"error_code":       float64(503),
+							"keywords":         []any{"overloaded"},
+							"duration_minutes": float64(10),
+						},
+					},
+				},
+			},
+			statusCode: 503,
+			body:       []byte(`overloaded service`),
+			expected:   ErrorPolicyTempUnscheduled,
+		},
+		{
+			name: "gemini_custom_codes_override_temp_unschedulable",
+			account: &Account{
+				ID:       104,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"custom_error_codes_enabled": true,
+					"custom_error_codes":         []any{float64(503)},
+					"temp_unschedulable_enabled": true,
+					"temp_unschedulable_rules": []any{
+						map[string]any{
+							"error_code":       float64(503),
+							"keywords":         []any{"overloaded"},
+							"duration_minutes": float64(10),
+						},
+					},
+				},
+			},
+			statusCode: 503,
+			body:       []byte(`overloaded`),
+			expected:   ErrorPolicyMatched, // custom codes take precedence
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			repo := &errorPolicyRepoStub{}
+			svc := NewRateLimitService(repo, nil, &config.Config{}, nil, nil)
+
+			result := svc.CheckErrorPolicy(context.Background(), tt.account, tt.statusCode, tt.body)
+			require.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+// ---------------------------------------------------------------------------
+// TestGeminiErrorPolicyIntegration — verifies the Gemini error handling
+// paths produce the correct behavior for each ErrorPolicyResult.
+//
+// These tests simulate the inline error policy switch in handleClaudeCompat
+// and forwardNativeGemini by calling the same methods in the same order.
+// ---------------------------------------------------------------------------
+
+func TestGeminiErrorPolicyIntegration(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	tests := []struct {
+		name                 string
+		account              *Account
+		statusCode           int
+		respBody             []byte
+		expectFailover       bool // expect UpstreamFailoverError
+		expectHandleError    bool // expect handleGeminiUpstreamError to be called
+		expectShouldFailover bool // for None path, whether shouldFailover triggers
+	}{
+		{
+			name: "custom_codes_matched_429_failover",
+			account: &Account{
+				ID:       200,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"custom_error_codes_enabled": true,
+					"custom_error_codes":         []any{float64(429)},
+				},
+			},
+			statusCode:        429,
+			respBody:          []byte(`{"error":"rate limited"}`),
+			expectFailover:    true,
+			expectHandleError: true,
+		},
+		{
+			name: "custom_codes_skipped_500_no_failover",
+			account: &Account{
+				ID:       201,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"custom_error_codes_enabled": true,
+					"custom_error_codes":         []any{float64(429)},
+				},
+			},
+			statusCode:        500,
+			respBody:          []byte(`{"error":"internal"}`),
+			expectFailover:    false,
+			expectHandleError: false,
+		},
+		{
+			name: "temp_unschedulable_matched_failover",
+			account: &Account{
+				ID:       202,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+				Credentials: map[string]any{
+					"temp_unschedulable_enabled": true,
+					"temp_unschedulable_rules": []any{
+						map[string]any{
+							"error_code":       float64(503),
+							"keywords":         []any{"overloaded"},
+							"duration_minutes": float64(10),
+						},
+					},
+				},
+			},
+			statusCode:        503,
+			respBody:          []byte(`overloaded`),
+			expectFailover:    true,
+			expectHandleError: true,
+		},
+		{
+			name: "no_policy_429_failover_via_shouldFailover",
+			account: &Account{
+				ID:       203,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+			},
+			statusCode:           429,
+			respBody:             []byte(`{"error":"rate limited"}`),
+			expectFailover:       true,
+			expectHandleError:    true,
+			expectShouldFailover: true,
+		},
+		{
+			name: "no_policy_400_no_failover",
+			account: &Account{
+				ID:       204,
+				Type:     AccountTypeAPIKey,
+				Platform: PlatformGemini,
+			},
+			statusCode:        400,
+			respBody:          []byte(`{"error":"bad request"}`),
+			expectFailover:    false,
+			expectHandleError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			repo := &geminiErrorPolicyRepo{}
+			rlSvc := NewRateLimitService(repo, nil, &config.Config{}, nil, nil)
+			svc := &GeminiMessagesCompatService{
+				accountRepo:      repo,
+				rateLimitService: rlSvc,
+			}
+
+			writer := httptest.NewRecorder()
+			c, _ := gin.CreateTestContext(writer)
+			c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages", nil)
+
+			// Simulate the Claude compat error handling path (same logic as native).
+			// This mirrors the inline switch in handleClaudeCompat.
+			var handleErrorCalled bool
+			var gotFailover bool
+
+			ctx := context.Background()
+			statusCode := tt.statusCode
+			respBody := tt.respBody
+			account := tt.account
+			headers := http.Header{}
+
+			if svc.rateLimitService != nil {
+				switch svc.rateLimitService.CheckErrorPolicy(ctx, account, statusCode, respBody) {
+				case ErrorPolicySkipped:
+					// Skipped → return error directly (no handleGeminiUpstreamError, no failover)
+					gotFailover = false
+					handleErrorCalled = false
+					goto verify
+				case ErrorPolicyMatched, ErrorPolicyTempUnscheduled:
+					svc.handleGeminiUpstreamError(ctx, account, statusCode, headers, respBody)
+					handleErrorCalled = true
+					gotFailover = true
+					goto verify
+				}
+			}
+
+			// ErrorPolicyNone → original logic
+			svc.handleGeminiUpstreamError(ctx, account, statusCode, headers, respBody)
+			handleErrorCalled = true
+			if svc.shouldFailoverGeminiUpstreamError(statusCode) {
+				gotFailover = true
+			}
+
+		verify:
+			require.Equal(t, tt.expectFailover, gotFailover, "failover mismatch")
+			require.Equal(t, tt.expectHandleError, handleErrorCalled, "handleGeminiUpstreamError call mismatch")
+
+			if tt.expectShouldFailover {
+				require.True(t, svc.shouldFailoverGeminiUpstreamError(statusCode),
+					"shouldFailoverGeminiUpstreamError should return true for status %d", statusCode)
+			}
+		})
+	}
+}
+
+// ---------------------------------------------------------------------------
+// TestGeminiErrorPolicy_NilRateLimitService — verifies nil safety
+// ---------------------------------------------------------------------------
+
+func TestGeminiErrorPolicy_NilRateLimitService(t *testing.T) {
+	svc := &GeminiMessagesCompatService{
+		rateLimitService: nil,
+	}
+
+	// When rateLimitService is nil, error policy is skipped → falls through to
+	// shouldFailoverGeminiUpstreamError (original logic).
+	// Verify this doesn't panic and follows expected behavior.
+
+	ctx := context.Background()
+	account := &Account{
+		ID:       300,
+		Type:     AccountTypeAPIKey,
+		Platform: PlatformGemini,
+		Credentials: map[string]any{
+			"custom_error_codes_enabled": true,
+			"custom_error_codes":         []any{float64(429)},
+		},
+	}
+
+	// The nil check should prevent CheckErrorPolicy from being called
+	if svc.rateLimitService != nil {
+		t.Fatal("rateLimitService should be nil for this test")
+	}
+
+	// shouldFailoverGeminiUpstreamError still works
+	require.True(t, svc.shouldFailoverGeminiUpstreamError(429))
+	require.False(t, svc.shouldFailoverGeminiUpstreamError(400))
+
+	// handleGeminiUpstreamError should not panic with nil rateLimitService
+	require.NotPanics(t, func() {
+		svc.handleGeminiUpstreamError(ctx, account, 500, http.Header{}, []byte(`error`))
+	})
+}
+
+// ---------------------------------------------------------------------------
+// geminiErrorPolicyRepo — minimal AccountRepository stub for Gemini error
+// policy tests. Embeds mockAccountRepoForGemini and adds tracking.
+// ---------------------------------------------------------------------------
+
+type geminiErrorPolicyRepo struct {
+	mockAccountRepoForGemini
+	setErrorCalls       int
+	setRateLimitedCalls int
+	setTempCalls        int
+}
+
+func (r *geminiErrorPolicyRepo) SetError(_ context.Context, _ int64, _ string) error {
+	r.setErrorCalls++
+	return nil
+}
+
+func (r *geminiErrorPolicyRepo) SetRateLimited(_ context.Context, _ int64, _ time.Time) error {
+	r.setRateLimitedCalls++
+	return nil
+}
+
+func (r *geminiErrorPolicyRepo) SetTempUnschedulable(_ context.Context, _ int64, _ time.Time, _ string) error {
+	r.setTempCalls++
+	return nil
+}

backend/internal/service/gemini_messages_compat_service.go

@@ -831,12 +831,17 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 
 	if resp.StatusCode >= 400 {
 		respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
-		tempMatched := false
+		// 统一错误策略：自定义错误码 + 临时不可调度
 		if s.rateLimitService != nil {
-			tempMatched = s.rateLimitService.HandleTempUnschedulable(ctx, account, resp.StatusCode, respBody)
+			switch s.rateLimitService.CheckErrorPolicy(ctx, account, resp.StatusCode, respBody) {
+			case ErrorPolicySkipped:
+				upstreamReqID := resp.Header.Get(requestIDHeader)
+				if upstreamReqID == "" {
+					upstreamReqID = resp.Header.Get("x-goog-request-id")
 				}
+				return nil, s.writeGeminiMappedError(c, account, resp.StatusCode, upstreamReqID, respBody)
+			case ErrorPolicyMatched, ErrorPolicyTempUnscheduled:
 				s.handleGeminiUpstreamError(ctx, account, resp.StatusCode, resp.Header, respBody)
-		if tempMatched {
 				upstreamReqID := resp.Header.Get(requestIDHeader)
 				if upstreamReqID == "" {
 					upstreamReqID = resp.Header.Get("x-goog-request-id")
@@ -863,6 +868,10 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 				})
 				return nil, &UpstreamFailoverError{StatusCode: resp.StatusCode, ResponseBody: respBody}
 			}
+		}
+
+		// ErrorPolicyNone → 原有逻辑
+		s.handleGeminiUpstreamError(ctx, account, resp.StatusCode, resp.Header, respBody)
 		if s.shouldFailoverGeminiUpstreamError(resp.StatusCode) {
 			upstreamReqID := resp.Header.Get(requestIDHeader)
 			if upstreamReqID == "" {
@@ -1249,14 +1258,9 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 
 	if resp.StatusCode >= 400 {
 		respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
-		tempMatched := false
-		if s.rateLimitService != nil {
-			tempMatched = s.rateLimitService.HandleTempUnschedulable(ctx, account, resp.StatusCode, respBody)
-		}
-		s.handleGeminiUpstreamError(ctx, account, resp.StatusCode, resp.Header, respBody)
-
 		// Best-effort fallback for OAuth tokens missing AI Studio scopes when calling countTokens.
 		// This avoids Gemini SDKs failing hard during preflight token counting.
+		// Checked before error policy so it always works regardless of custom error codes.
 		if action == "countTokens" && isOAuth && isGeminiInsufficientScope(resp.Header, respBody) {
 			estimated := estimateGeminiCountTokens(body)
 			c.JSON(http.StatusOK, map[string]any{"totalTokens": estimated})
@@ -1270,7 +1274,19 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 			}, nil
 		}
 
-		if tempMatched {
+		// 统一错误策略：自定义错误码 + 临时不可调度
+		if s.rateLimitService != nil {
+			switch s.rateLimitService.CheckErrorPolicy(ctx, account, resp.StatusCode, respBody) {
+			case ErrorPolicySkipped:
+				respBody = unwrapIfNeeded(isOAuth, respBody)
+				contentType := resp.Header.Get("Content-Type")
+				if contentType == "" {
+					contentType = "application/json"
+				}
+				c.Data(resp.StatusCode, contentType, respBody)
+				return nil, fmt.Errorf("gemini upstream error: %d (skipped by error policy)", resp.StatusCode)
+			case ErrorPolicyMatched, ErrorPolicyTempUnscheduled:
+				s.handleGeminiUpstreamError(ctx, account, resp.StatusCode, resp.Header, respBody)
 				evBody := unwrapIfNeeded(isOAuth, respBody)
 				upstreamMsg := strings.TrimSpace(extractUpstreamErrorMessage(evBody))
 				upstreamMsg = sanitizeUpstreamErrorMessage(upstreamMsg)
@@ -1294,6 +1310,10 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 				})
 				return nil, &UpstreamFailoverError{StatusCode: resp.StatusCode, ResponseBody: respBody}
 			}
+		}
+
+		// ErrorPolicyNone → 原有逻辑
+		s.handleGeminiUpstreamError(ctx, account, resp.StatusCode, resp.Header, respBody)
 		if s.shouldFailoverGeminiUpstreamError(resp.StatusCode) {
 			evBody := unwrapIfNeeded(isOAuth, respBody)
 			upstreamMsg := strings.TrimSpace(extractUpstreamErrorMessage(evBody))