feat: add diagnostics and telemetry runtime

tests/unit/storage-registry.test.js

@@ -1,4 +1,4 @@
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 
 import { createBrowserStorageAdapter } from "../../src/adapters/storage/browser-storage-adapter.js";
 import {
@@ -61,13 +61,27 @@ describe("storage registry", () => {
 
   it("falls back to memory when preference storage quota is exceeded", () => {
     const localStorage = createStorage({ quota: true });
-    const adapter = createBrowserStorageAdapter({ localStorage });
+    const record = vi.fn();
+    const adapter = createBrowserStorageAdapter({
+      localStorage,
+      diagnostics: { record },
+    });
     expect(adapter.write("COLOR_SCHEME", "dark")).toMatchObject({
       ok: false,
       fallback: "memory",
       error: { kind: "STORAGE_QUOTA_EXCEEDED" },
     });
     expect(adapter.read("COLOR_SCHEME")).toEqual({ ok: true, value: "dark" });
+    expect(record).toHaveBeenCalledOnce();
+    expect(record).toHaveBeenCalledWith({
+      level: "warn",
+      eventId: "storage.operation.failed",
+      context: {
+        operation: "write:COLOR_SCHEME",
+        error_kind: "STORAGE_QUOTA_EXCEEDED",
+      },
+    });
+    expect(JSON.stringify(record.mock.calls)).not.toContain("dark");
   });
 
   it("discards data from a previous schema version", () => {