feat: add diagnostics events and otel exporter

src/infra/diagnostic-events.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, test } from "vitest";
+
+import {
+  emitDiagnosticEvent,
+  onDiagnosticEvent,
+  resetDiagnosticEventsForTest,
+} from "./diagnostic-events.js";
+
+describe("diagnostic-events", () => {
+  test("emits monotonic seq", async () => {
+    resetDiagnosticEventsForTest();
+    const seqs: number[] = [];
+    const stop = onDiagnosticEvent((evt) => seqs.push(evt.seq));
+
+    emitDiagnosticEvent({
+      type: "model.usage",
+      usage: { total: 1 },
+    });
+    emitDiagnosticEvent({
+      type: "model.usage",
+      usage: { total: 2 },
+    });
+
+    stop();
+
+    expect(seqs).toEqual([1, 2]);
+  });
+});

src/infra/diagnostic-events.ts

@@ -0,0 +1,60 @@
+import type { ClawdbotConfig } from "../config/config.js";
+
+export type DiagnosticUsageEvent = {
+  type: "model.usage";
+  ts: number;
+  seq: number;
+  sessionKey?: string;
+  sessionId?: string;
+  channel?: string;
+  provider?: string;
+  model?: string;
+  usage: {
+    input?: number;
+    output?: number;
+    cacheRead?: number;
+    cacheWrite?: number;
+    promptTokens?: number;
+    total?: number;
+  };
+  context?: {
+    limit?: number;
+    used?: number;
+  };
+  costUsd?: number;
+  durationMs?: number;
+};
+
+export type DiagnosticEventPayload = DiagnosticUsageEvent;
+
+let seq = 0;
+const listeners = new Set<(evt: DiagnosticEventPayload) => void>();
+
+export function isDiagnosticsEnabled(config?: ClawdbotConfig): boolean {
+  return config?.diagnostics?.enabled === true;
+}
+
+export function emitDiagnosticEvent(event: Omit<DiagnosticEventPayload, "seq" | "ts">) {
+  const enriched: DiagnosticEventPayload = {
+    ...event,
+    seq: (seq += 1),
+    ts: Date.now(),
+  };
+  for (const listener of listeners) {
+    try {
+      listener(enriched);
+    } catch {
+      // Ignore listener failures.
+    }
+  }
+}
+
+export function onDiagnosticEvent(listener: (evt: DiagnosticEventPayload) => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+export function resetDiagnosticEventsForTest(): void {
+  seq = 0;
+  listeners.clear();
+}