diff --git a/tests/nostr/countDiagnostics.test.mjs b/tests/nostr/countDiagnostics.test.mjs
new file mode 100644
index 00000000..644ea02f
--- /dev/null
+++ b/tests/nostr/countDiagnostics.test.mjs
@@ -0,0 +1,182 @@
+import { describe, it, before, after, afterEach, beforeEach } from "node:test";
+import assert from "node:assert/strict";
+import "../test-setup.mjs";
+
+describe("countDiagnostics", () => {
+  let countDiagnostics;
+  let warnCalls = [];
+  let originalConsoleWarn;
+
+  before(async () => {
+    // Setup environment before importing modules
+    globalThis.__BITVID_DEV_MODE_OVERRIDE__ = true;
+    globalThis.__BITVID_VERBOSE_DEV_MODE_OVERRIDE__ = true;
+
+    // Mock console.warn
+    originalConsoleWarn = console.warn;
+    console.warn = (...args) => {
+      warnCalls.push(args);
+      // originalConsoleWarn(...args); // Uncomment to see logs
+    };
+
+    // Dynamic import to pick up the overrides
+    countDiagnostics = await import("../../js/nostr/countDiagnostics.js");
+  });
+
+  after(() => {
+    if (originalConsoleWarn) {
+      console.warn = originalConsoleWarn;
+    }
+  });
+
+  afterEach(() => {
+    warnCalls = [];
+    // Reset window flags between tests if needed, though most tests set them explicitly
+    if (typeof window !== "undefined") {
+      delete window.__BITVID_VERBOSE_DEV_MODE__;
+    }
+  });
+
+  describe("isVerboseDiagnosticsEnabled", () => {
+    it("should return true by default (due to override)", () => {
+      assert.equal(countDiagnostics.isVerboseDiagnosticsEnabled(), true);
+    });
+
+    it("should return false if window.__BITVID_VERBOSE_DEV_MODE__ is false", () => {
+      window.__BITVID_VERBOSE_DEV_MODE__ = false;
+      assert.equal(countDiagnostics.isVerboseDiagnosticsEnabled(), false);
+    });
+
+    it("should return true if window.__BITVID_VERBOSE_DEV_MODE__ is true", () => {
+      window.__BITVID_VERBOSE_DEV_MODE__ = true;
+      assert.equal(countDiagnostics.isVerboseDiagnosticsEnabled(), true);
+    });
+
+    it("should fall back to isVerboseDevMode if window flag is not boolean", () => {
+      window.__BITVID_VERBOSE_DEV_MODE__ = "invalid";
+      assert.equal(countDiagnostics.isVerboseDiagnosticsEnabled(), true);
+
+      window.__BITVID_VERBOSE_DEV_MODE__ = 123;
+      assert.equal(countDiagnostics.isVerboseDiagnosticsEnabled(), true);
+    });
+  });
+
+  describe("logRelayCountFailure", () => {
+    it("should log warning for new relay URL", () => {
+      const relayUrl = "wss://relay.example.com";
+      const error = new Error("Connection failed");
+
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+
+      assert.equal(warnCalls.length, 1);
+      assert.match(warnCalls[0][0], /COUNT request failed on wss:\/\/relay.example.com/);
+      assert.deepEqual(warnCalls[0][1], error);
+    });
+
+    it("should suppress 'Failed to connect to relay' errors", () => {
+      const relayUrl = "wss://relay.bad.com";
+      const error = new Error("Failed to connect to relay wss://relay.bad.com");
+
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+
+      assert.equal(warnCalls.length, 0);
+    });
+
+    it("should throttle duplicate warnings for the same relay", () => {
+      const relayUrl = "wss://relay.throttled.com";
+      const error = new Error("Timeout");
+
+      // First call logs
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+      assert.equal(warnCalls.length, 1);
+
+      // Second call suppresses
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+      assert.equal(warnCalls.length, 1);
+    });
+
+    it("should handle empty or non-string relay URLs", () => {
+      const error = new Error("Unknown error");
+
+      countDiagnostics.logRelayCountFailure(null, error);
+      assert.equal(warnCalls.length, 1);
+      assert.match(warnCalls[0][0], /COUNT request failed on \(unknown relay\)/);
+
+      warnCalls = [];
+      // This call should be throttled because both null and "" map to "(unknown relay)"
+      countDiagnostics.logRelayCountFailure("", error);
+      assert.equal(warnCalls.length, 0);
+    });
+  });
+
+  describe("Other Loggers", () => {
+    // These use fixed keys so we can only test them once for "logging" behavior per process/suite run
+
+    it("should log timeout cleanup failure once", () => {
+      const error = new Error("Cleanup failed");
+      countDiagnostics.logCountTimeoutCleanupFailure(error);
+
+      assert.equal(warnCalls.length, 1);
+      assert.match(warnCalls[0][0], /COUNT timeout cleanup failed/);
+
+      // Verify throttling immediately
+      countDiagnostics.logCountTimeoutCleanupFailure(error);
+      assert.equal(warnCalls.length, 1);
+    });
+
+    it("should log rebroadcast failure once", () => {
+      const error = new Error("Rebroadcast failed");
+      countDiagnostics.logRebroadcastCountFailure(error);
+
+      assert.equal(warnCalls.length, 1);
+      assert.match(warnCalls[0][0], /COUNT request for rebroadcast failed/);
+
+      // Verify throttling
+      countDiagnostics.logRebroadcastCountFailure(error);
+      assert.equal(warnCalls.length, 1);
+    });
+
+    it("should log view count failure once", () => {
+      const error = new Error("View count failed");
+      countDiagnostics.logViewCountFailure(error);
+
+      assert.equal(warnCalls.length, 1);
+      assert.match(warnCalls[0][0], /COUNT view request failed/);
+
+      // Verify throttling
+      countDiagnostics.logViewCountFailure(error);
+      assert.equal(warnCalls.length, 1);
+    });
+  });
+
+  describe("Verbose Mode Disabled", () => {
+    beforeEach(() => {
+        window.__BITVID_VERBOSE_DEV_MODE__ = false;
+    });
+
+    it("should not log even for new keys when disabled", () => {
+      const relayUrl = "wss://relay.silent.com";
+      const error = new Error("Silent error");
+
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+      assert.equal(warnCalls.length, 0);
+    });
+
+    it("should not consume throttle key when disabled", () => {
+      const relayUrl = "wss://relay.delayed.com";
+      const error = new Error("Delayed error");
+
+      // Disabled: no log, key not added
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+      assert.equal(warnCalls.length, 0);
+
+      // Enable verbose mode
+      window.__BITVID_VERBOSE_DEV_MODE__ = true;
+
+      // Should log now because previous call didn't register key
+      countDiagnostics.logRelayCountFailure(relayUrl, error);
+      assert.equal(warnCalls.length, 1);
+      assert.match(warnCalls[0][0], /COUNT request failed on wss:\/\/relay.delayed.com/);
+    });
+  });
+});