**feat(auth): add AuthIndex for diagnostics and ensure usage recording**

internal/runtime/executor/iflow_executor.go

@@ -112,6 +112,8 @@ func (e *IFlowExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, re
 	}
 	appendAPIResponseChunk(ctx, e.cfg, data)
 	reporter.publish(ctx, parseOpenAIUsage(data))
+	// Ensure usage is recorded even if upstream omits usage metadata.
+	reporter.ensurePublished(ctx)
 
 	var param any
 	out := sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, data, &param)
@@ -217,6 +219,8 @@ func (e *IFlowExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Au
 			reporter.publishFailure(ctx)
 			out <- cliproxyexecutor.StreamChunk{Err: errScan}
 		}
+		// Guarantee a usage record exists even if the stream never emitted usage data.
+		reporter.ensurePublished(ctx)
 	}()
 
 	return stream, nil

internal/runtime/executor/usage_helpers.go

@@ -18,6 +18,7 @@ type usageReporter struct {
 	provider    string
 	model       string
 	authID      string
+	authIndex   uint64
 	apiKey      string
 	source      string
 	requestedAt time.Time
@@ -35,6 +36,7 @@ func newUsageReporter(ctx context.Context, provider, model string, auth *cliprox
 	}
 	if auth != nil {
 		reporter.authID = auth.ID
+		reporter.authIndex = auth.Index
 	}
 	return reporter
 }
@@ -76,6 +78,7 @@ func (r *usageReporter) publishWithOutcome(ctx context.Context, detail usage.Det
 			Source:      r.source,
 			APIKey:      r.apiKey,
 			AuthID:      r.authID,
+			AuthIndex:   r.authIndex,
 			RequestedAt: r.requestedAt,
 			Failed:      failed,
 			Detail:      detail,
@@ -98,6 +101,7 @@ func (r *usageReporter) ensurePublished(ctx context.Context) {
 			Source:      r.source,
 			APIKey:      r.apiKey,
 			AuthID:      r.authID,
+			AuthIndex:   r.authIndex,
 			RequestedAt: r.requestedAt,
 			Failed:      false,
 			Detail:      usage.Detail{},