Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/handler/no_account_error.go

@@ -0,0 +1,146 @@
+package handler
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+)
+
+// noAccountErrorClassification describes the HTTP response to emit when
+// account selection failed with ErrNoAvailableAccounts. Handlers obtain it
+// via classifyNoAccountError and choose between:
+//
+//   - 404 model_not_found — the group has accounts, but none of them are
+//     configured to serve the requested model (config / typo / unsupported
+//     model). Returning 503 here misleads operators and trips reverse-proxy
+//     health checks; 404 lets the client surface the real problem.
+//
+//   - 503 api_error — accounts that could serve the model exist but are
+//     temporarily exhausted (rate limit, quota auto-pause, runtime block) OR
+//     the group has no accounts at all. Both stay on 503 because retrying
+//     after a backoff can plausibly succeed (or, in the empty-pool case, the
+//     operator may be in the middle of adding accounts).
+type noAccountErrorClassification struct {
+	Status        int
+	ErrType       string
+	Message       string
+	ModelNotFound bool // true when this is a 404 model_not_found classification
+}
+
+// classifyNoAccountError decides between 404 model_not_found and 503
+// api_error for "no available accounts" failures.
+//
+// The classifier intentionally does not consume the original error: the
+// selection layer never tells us *why* the pool came up empty (rate-limited
+// vs. unsupported model are both wrapped as ErrNoAvailableAccounts). Instead
+// we re-check pool composition through DiagnoseModelAvailabilityForPlatform.
+// Its dedicated database query considers only persistent eligibility
+// (active status + schedulable setting) and model_mapping, bypassing scheduler
+// snapshots and transient filters. That guarantees a 404 is only returned
+// when persistent account/group/model configuration must change before the
+// request can succeed.
+//
+// routingModel is the model name that account selection actually compared
+// against (i.e. after group-level dispatch mapping). displayModel is the
+// raw model the caller asked for; it is used only in the user-facing error
+// message so that internal mapping details don't leak. Most callers pass
+// the same value for both.
+//
+// platform is the platform the request was routed to (use
+// service.PlatformOpenAI / PlatformAnthropic / PlatformGemini). It is
+// required because Anthropic/Gemini routes additionally surface
+// mixed-scheduled Antigravity accounts; passing the wrong platform would
+// flip a legitimate 503 to a misleading 404 (or vice versa).
+func classifyNoAccountError(
+	ctx context.Context,
+	diag service.ModelAvailabilityDiagnoser,
+	apiKey *service.APIKey,
+	routingModel string,
+	displayModel string,
+	platform string,
+) noAccountErrorClassification {
+	fallback := noAccountErrorClassification{
+		Status:  http.StatusServiceUnavailable,
+		ErrType: "api_error",
+		Message: "Service temporarily unavailable",
+	}
+
+	routingModel = strings.TrimSpace(routingModel)
+	displayModel = strings.TrimSpace(displayModel)
+	if displayModel == "" {
+		displayModel = routingModel
+	}
+	if diag == nil || apiKey == nil || apiKey.GroupID == nil || routingModel == "" {
+		return fallback
+	}
+
+	result := diag.DiagnoseModelAvailabilityForPlatform(ctx, apiKey.GroupID, routingModel, platform)
+	if result.HasAccountsInPool && !result.HasModelSupport {
+		return noAccountErrorClassification{
+			Status:        http.StatusNotFound,
+			ErrType:       "model_not_found",
+			Message:       fmt.Sprintf("Model %q is not supported by any configured account in this group", displayModel),
+			ModelNotFound: true,
+		}
+	}
+	return fallback
+}
+
+// classifyNoAccountErrorFromGin is a thin wrapper that forwards the gin
+// context's underlying request context. Most call sites already have a
+// *gin.Context handy, so this keeps the call sites uncluttered.
+func classifyNoAccountErrorFromGin(
+	c *gin.Context,
+	diag service.ModelAvailabilityDiagnoser,
+	apiKey *service.APIKey,
+	routingModel string,
+	displayModel string,
+	platform string,
+) noAccountErrorClassification {
+	ctx := context.Background()
+	if c != nil && c.Request != nil {
+		ctx = c.Request.Context()
+	}
+	classification := classifyNoAccountError(ctx, diag, apiKey, routingModel, displayModel, platform)
+	if classification.ModelNotFound {
+		service.MarkOpsClientBusinessLimited(c, service.OpsClientBusinessLimitedReasonLocalModelConfiguration)
+	}
+	return classification
+}
+
+func classifyOpenAICompatibleNoAccountErrorFromGin(
+	c *gin.Context,
+	diag service.ModelAvailabilityDiagnoser,
+	apiKey *service.APIKey,
+	routingModel string,
+	displayModel string,
+) noAccountErrorClassification {
+	ctx := context.Background()
+	if c != nil && c.Request != nil {
+		ctx = c.Request.Context()
+	}
+	return classifyNoAccountErrorFromGin(
+		c,
+		diag,
+		apiKey,
+		routingModel,
+		displayModel,
+		openAICompatibleRequestPlatform(ctx, apiKey),
+	)
+}
+
+func openAICompatibleSelectionErrorForLog(err error, platform string) error {
+	if err == nil || platform != service.PlatformGrok {
+		return err
+	}
+	message := strings.ReplaceAll(err.Error(), "OpenAI accounts", "Grok accounts")
+	if message == err.Error() {
+		return err
+	}
+	return fmt.Errorf("%s", message)
+}