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

backend/internal/service/openai_gateway_model_availability.go

@@ -0,0 +1,69 @@
+package service
+
+import (
+	"context"
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+)
+
+// DiagnoseModelAvailabilityForPlatform reports whether the requested model
+// is configured to be served by any persistently eligible OpenAI-compatible
+// account in the group for the given platform (e.g. PlatformOpenAI,
+// PlatformGrok). The platform scopes the candidate pool so distinct
+// OpenAI-compatible platforms do not cross-contaminate diagnosis results.
+// The query bypasses scheduler snapshots and ignores transient runtime state.
+//
+// Safe to call on the error path: returns {true,true} on any internal
+// failure or when the inputs preclude meaningful diagnosis (empty model,
+// nil service), so callers stay on the 503 fallback branch.
+func (s *OpenAIGatewayService) DiagnoseModelAvailabilityForPlatform(
+	ctx context.Context,
+	groupID *int64,
+	requestedModel string,
+	platform string,
+) ModelAvailabilityDiagnosis {
+	if s == nil {
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+	requestedModel = strings.TrimSpace(requestedModel)
+	if requestedModel == "" {
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+	if s.accountRepo == nil {
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+
+	platform = NormalizeOpenAICompatiblePlatform(platform)
+	queryGroupID := groupID
+	includeGrouped := false
+	if s.cfg != nil && s.cfg.RunMode == config.RunModeSimple {
+		queryGroupID = nil
+		includeGrouped = true
+	}
+	accounts, err := s.accountRepo.ListModelAvailabilityCandidates(
+		ctx,
+		queryGroupID,
+		[]string{platform},
+		includeGrouped,
+	)
+	if err != nil {
+		// Conservative fallback so the caller keeps returning 503; we do not
+		// want a transient lookup failure to flip into 404 model_not_found.
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+
+	diag := ModelAvailabilityDiagnosis{}
+	for i := range accounts {
+		diag.HasAccountsInPool = true
+		// Mirrors the per-candidate filter used during account selection
+		// (openai_account_scheduler.isAccountRequestCompatible): empty
+		// model_mapping accepts everything; otherwise the explicit / wildcard
+		// mapping must match.
+		if accounts[i].IsModelSupported(requestedModel) {
+			diag.HasModelSupport = true
+			return diag
+		}
+	}
+	return diag
+}