feat: expose usage stats via shared runtime StatsCache

src/lib/runtime.ts

@@ -1,6 +1,8 @@
 import { EventFeed } from "./event-feed";
 import { InflightTracker } from "./inflight-tracker";
 import { MetricsPoller } from "./metrics-poller";
+import { StatsCache } from "./stats-cache";
+import { type UsageStats } from "./stats";
 import { type LlamaSwapConfig } from "./util";
 
 class Runtime {
@@ -9,6 +11,8 @@ class Runtime {
   private cfg?: LlamaSwapConfig;
   private feed?: EventFeed;
   private poller?: MetricsPoller;
+  private statsCache?: StatsCache;
+  private statsUnsub?: () => void;
   private listeners = new Set<() => void>();
 
   ensureConnections(cfg: LlamaSwapConfig): void {
@@ -18,11 +22,15 @@ class Runtime {
       this.poller?.stop();
       this.feed = undefined;
       this.poller = undefined;
+      this.statsUnsub?.();
+      this.statsCache = undefined;
+      this.statsUnsub = undefined;
       this.cfg = cfg;
     }
     if (!this.feed) {
       this.feed = new EventFeed(cfg, (ev) => {
         this.tracker.apply(ev);
+        if (ev.type === "activity") this.statsCache?.scheduleRefresh();
         this.emit();
       });
       this.feed.setStatusHandler((connected) => {
@@ -36,12 +44,25 @@ class Runtime {
       this.poller.on(() => this.emit());
       this.poller.start();
     }
+    if (!this.statsCache) {
+      this.statsCache = new StatsCache(cfg);
+      this.statsUnsub = this.statsCache.onChange(() => this.emit());
+    }
   }
 
   get pollerInstance(): MetricsPoller | undefined {
     return this.poller;
   }
 
+  getStats(modelId: string): UsageStats | undefined {
+    return this.statsCache?.get(modelId);
+  }
+
+  watchStats(modelId: string): () => void {
+    this.statsCache?.register(modelId);
+    return () => this.statsCache?.unregister(modelId);
+  }
+
   subscribe(listener: () => void): () => void {
     this.listeners.add(listener);
     return () => {