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

backend/internal/service/gateway_model_availability.go

@@ -0,0 +1,111 @@
+package service
+
+import (
+	"context"
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+)
+
+// ModelAvailabilityDiagnosis describes whether the requested model can be
+// served by any persistently eligible account in the group (active with its
+// schedulable setting enabled), ignoring transient state such as rate limits,
+// overload, temporary unschedulability, and runtime blocks. Handlers use this
+// on the "no available accounts" error path to distinguish 404
+// model_not_found from 503 service_unavailable.
+type ModelAvailabilityDiagnosis struct {
+	// HasAccountsInPool is true if the group has at least one persistently
+	// eligible account on the queried platform (or, for Anthropic/Gemini, on
+	// the platform plus mixed-scheduled Antigravity accounts).
+	HasAccountsInPool bool
+	// HasModelSupport is true if at least one account's model mapping admits
+	// the requested model.
+	HasModelSupport bool
+}
+
+// ModelAvailabilityDiagnoser is implemented by gateway services that can
+// report whether the requested model is configured to be served by any
+// account. Both *GatewayService and *OpenAIGatewayService implement this so
+// handlers in either package can share a single classifier.
+type ModelAvailabilityDiagnoser interface {
+	DiagnoseModelAvailabilityForPlatform(
+		ctx context.Context,
+		groupID *int64,
+		requestedModel string,
+		platform string,
+	) ModelAvailabilityDiagnosis
+}
+
+// DiagnoseModelAvailabilityForPlatform inspects accounts enabled for scheduling
+// by persistent configuration and returns whether the requested model is
+// configured to be served by any of them. The dedicated repository query
+// bypasses scheduler snapshots and deliberately ignores transient rate-limit,
+// overload, temporary-unschedulable, expiry, quota, and runtime-block state.
+//
+// Safe to call on the error path: returns {true,true} on any internal failure
+// or when the inputs preclude meaningful diagnosis (empty model, etc.), so
+// callers stay on the 503 fallback branch.
+func (s *GatewayService) 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 == "" {
+		// No model specified — cannot decide model_not_found. Caller falls back to 503.
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+	if strings.TrimSpace(platform) == "" {
+		// Without a platform we cannot scope the lookup; bail out to the
+		// 503 branch rather than make an unscoped scan.
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+
+	if s.accountRepo == nil {
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+
+	useMixed := platform == PlatformAnthropic || platform == PlatformGemini
+	platforms := []string{platform}
+	if useMixed {
+		platforms = append(platforms, PlatformAntigravity)
+	}
+
+	queryGroupID := groupID
+	includeGrouped := false
+	if useMixed {
+		// Preserve the generic scheduler's scope rules: an explicit group wins
+		// for mixed scheduling, while group-less simple mode scans all accounts.
+		if groupID == nil && s.cfg != nil && s.cfg.RunMode == config.RunModeSimple {
+			includeGrouped = true
+		}
+	} else if s.cfg != nil && s.cfg.RunMode == config.RunModeSimple {
+		queryGroupID = nil
+		includeGrouped = true
+	}
+
+	accounts, err := s.accountRepo.ListModelAvailabilityCandidates(ctx, queryGroupID, platforms, includeGrouped)
+	if err != nil {
+		// Conservative fallback: pretend everything is fine so the caller
+		// returns 503 (we don't want to flip to 404 just because a lookup
+		// hiccup'd).
+		return ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasModelSupport: true}
+	}
+
+	diag := ModelAvailabilityDiagnosis{}
+	for i := range accounts {
+		if useMixed && accounts[i].Platform == PlatformAntigravity && !accounts[i].IsMixedSchedulingEnabled() {
+			continue
+		}
+		diag.HasAccountsInPool = true
+		if s.isModelSupportedByAccountWithContext(ctx, &accounts[i], requestedModel) {
+			diag.HasModelSupport = true
+			return diag
+		}
+	}
+	return diag
+}