feat(usage): add support for requested model alias handling

- Introduced methods for setting and retrieving model aliases in execution and usage contexts.
- Enhanced `UsageReporter` and related structures to include client-requested aliases.
- Updated tests to validate alias propagation and ensure correct usage reporting.
- Adjusted metadata handling in CLIProxyAPI executors to address alias integration.

sdk/cliproxy/auth/conductor.go

@@ -22,6 +22,7 @@ import (
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/thinking"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
 	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
+	coreusage "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/usage"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -827,6 +828,7 @@ func (m *Manager) executeStreamWithModelPool(ctx context.Context, executor Provi
 	if executor == nil {
 		return nil, &Error{Code: "executor_not_found", Message: "executor not registered"}
 	}
+	ctx = contextWithRequestedModelAlias(ctx, opts, routeModel)
 	var lastErr error
 	for idx, execModel := range execModels {
 		resultModel := m.stateModelForExecution(auth, routeModel, execModel, pooled)
@@ -1319,6 +1321,7 @@ func (m *Manager) executeMixedOnce(ctx context.Context, providers []string, req
 			execCtx = context.WithValue(execCtx, roundTripperContextKey{}, rt)
 			execCtx = context.WithValue(execCtx, "cliproxy.roundtripper", rt)
 		}
+		execCtx = contextWithRequestedModelAlias(execCtx, opts, routeModel)
 
 		models, pooled := m.preparedExecutionModels(auth, routeModel)
 		if len(models) == 0 {
@@ -1397,6 +1400,7 @@ func (m *Manager) executeCountMixedOnce(ctx context.Context, providers []string,
 			execCtx = context.WithValue(execCtx, roundTripperContextKey{}, rt)
 			execCtx = context.WithValue(execCtx, "cliproxy.roundtripper", rt)
 		}
+		execCtx = contextWithRequestedModelAlias(execCtx, opts, routeModel)
 
 		models, pooled := m.preparedExecutionModels(auth, routeModel)
 		if len(models) == 0 {
@@ -1534,6 +1538,36 @@ func hasRequestedModelMetadata(meta map[string]any) bool {
 	}
 }
 
+func contextWithRequestedModelAlias(ctx context.Context, opts cliproxyexecutor.Options, fallback string) context.Context {
+	alias := requestedModelAliasFromOptions(opts, fallback)
+	return coreusage.WithRequestedModelAlias(ctx, alias)
+}
+
+func requestedModelAliasFromOptions(opts cliproxyexecutor.Options, fallback string) string {
+	fallback = strings.TrimSpace(fallback)
+	if len(opts.Metadata) == 0 {
+		return fallback
+	}
+	raw, ok := opts.Metadata[cliproxyexecutor.RequestedModelMetadataKey]
+	if !ok || raw == nil {
+		return fallback
+	}
+	switch value := raw.(type) {
+	case string:
+		if strings.TrimSpace(value) == "" {
+			return fallback
+		}
+		return strings.TrimSpace(value)
+	case []byte:
+		if len(value) == 0 {
+			return fallback
+		}
+		return strings.TrimSpace(string(value))
+	default:
+		return fallback
+	}
+}
+
 func pinnedAuthIDFromMetadata(meta map[string]any) string {
 	if len(meta) == 0 {
 		return ""
@@ -3096,6 +3130,7 @@ func (m *Manager) tryAntigravityCreditsExecute(ctx context.Context, req cliproxy
 			creditsCtx = context.WithValue(creditsCtx, "cliproxy.roundtripper", rt)
 		}
 		creditsOpts := ensureRequestedModelMetadata(opts, routeModel)
+		creditsCtx = contextWithRequestedModelAlias(creditsCtx, creditsOpts, routeModel)
 		publishSelectedAuthMetadata(creditsOpts.Metadata, c.auth.ID)
 		models := m.executionModelCandidates(c.auth, routeModel)
 		if len(models) == 0 {