diff --git a/.gitignore b/.gitignore
index b947077..e6d5efa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 node_modules/
 dist/
+coverage/
+*.log
diff --git a/tests/pairing-auth-liveness.test.ts b/tests/pairing-auth-liveness.test.ts
new file mode 100644
index 0000000..8672f39
--- /dev/null
+++ b/tests/pairing-auth-liveness.test.ts
@@ -0,0 +1,486 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { createClientRecord, type ClientRecord } from "../plugin/core/persistence.js";
+import { createServerRuleRegistry, ServerRuleRegistryError } from "../plugin/core/rules.js";
+import { createPairingService } from "../plugin/services/pairing.js";
+
+// Inline protocol helpers (to avoid submodule dependency in tests)
+function createAuthRequestSigningInput(input: {
+  secret: string;
+  nonce: string;
+  proofTimestamp: number;
+}): string {
+  return JSON.stringify({
+    secret: input.secret,
+    nonce: input.nonce,
+    timestamp: input.proofTimestamp
+  });
+}
+
+function isTimestampFresh(
+  proofTimestamp: number,
+  now: number,
+  maxDriftSeconds: number = 10
+): { ok: true } | { ok: false; reason: "stale_timestamp" | "future_timestamp" } {
+  const drift = proofTimestamp - now;
+  if (Math.abs(drift) < maxDriftSeconds) {
+    return { ok: true };
+  }
+  return { ok: false, reason: drift < 0 ? "stale_timestamp" : "future_timestamp" };
+}
+
+describe("Yonexus.Server PairingService", () => {
+  it("creates a pending pairing request with ttl metadata", () => {
+    const record = createClientRecord("client-a");
+    const pairing = createPairingService({ now: () => 1_710_000_000 });
+
+    const request = pairing.createPairingRequest(record, { ttlSeconds: 180 });
+
+    expect(request.identifier).toBe("client-a");
+    expect(request.ttlSeconds).toBe(180);
+    expect(request.expiresAt).toBe(1_710_000_180);
+    expect(record.pairingStatus).toBe("pending");
+    expect(record.pairingCode).toBe(request.pairingCode);
+    expect(record.pairingNotifyStatus).toBe("pending");
+  });
+
+  it("confirms a valid pairing and clears pairing-only fields", () => {
+    const record = createClientRecord("client-a");
+    const pairing = createPairingService({ now: () => 1_710_000_100 });
+    const request = pairing.createPairingRequest(record, { ttlSeconds: 300 });
+
+    const result = pairing.confirmPairing(record, request.pairingCode);
+
+    expect(result).toMatchObject({
+      success: true,
+      pairedAt: 1_710_000_100
+    });
+    expect(typeof result.secret).toBe("string");
+    expect(record.pairingStatus).toBe("paired");
+    expect(record.secret).toBe(result.secret);
+    expect(record.pairingCode).toBeUndefined();
+    expect(record.pairingExpiresAt).toBeUndefined();
+    expect(record.pairingNotifyStatus).toBeUndefined();
+  });
+
+  it("rejects expired and invalid pairing confirmations without dirtying state", () => {
+    const record = createClientRecord("client-a");
+    let now = 1_710_000_000;
+    const pairing = createPairingService({ now: () => now });
+    const request = pairing.createPairingRequest(record, { ttlSeconds: 60 });
+
+    const invalid = pairing.confirmPairing(record, "WRONG-CODE-000");
+    expect(invalid).toEqual({ success: false, reason: "invalid_code" });
+    expect(record.pairingStatus).toBe("pending");
+    expect(record.pairingCode).toBe(request.pairingCode);
+
+    now = 1_710_000_100;
+    const expired = pairing.confirmPairing(record, request.pairingCode);
+    expect(expired).toEqual({ success: false, reason: "expired" });
+    expect(record.pairingStatus).toBe("unpaired");
+    expect(record.pairingCode).toBeUndefined();
+  });
+
+  it("marks notification delivery state transitions", () => {
+    const record = createClientRecord("client-a");
+    const pairing = createPairingService({ now: () => 1_710_000_000 });
+    pairing.createPairingRequest(record);
+
+    pairing.markNotificationSent(record);
+    expect(record.pairingNotifyStatus).toBe("sent");
+    expect(record.pairingNotifiedAt).toBe(1_710_000_000);
+
+    pairing.markNotificationFailed(record);
+    expect(record.pairingNotifyStatus).toBe("failed");
+  });
+});
+
+describe("Yonexus.Server RuleRegistry", () => {
+  it("dispatches exact-match rewritten messages to the registered processor", () => {
+    const registry = createServerRuleRegistry();
+    const processor = vi.fn();
+    registry.registerRule("chat_sync", processor);
+
+    const handled = registry.dispatch("chat_sync::client-a::{\"body\":\"hello\"}");
+
+    expect(handled).toBe(true);
+    expect(processor).toHaveBeenCalledWith("chat_sync::client-a::{\"body\":\"hello\"}");
+    expect(registry.hasRule("chat_sync")).toBe(true);
+    expect(registry.getRules()).toEqual(["chat_sync"]);
+  });
+
+  it("rejects reserved and duplicate rule registrations", () => {
+    const registry = createServerRuleRegistry();
+    registry.registerRule("chat_sync", () => undefined);
+
+    expect(() => registry.registerRule("builtin", () => undefined)).toThrow(ServerRuleRegistryError);
+    expect(() => registry.registerRule("chat_sync", () => undefined)).toThrow(
+      "Rule 'chat_sync' is already registered"
+    );
+  });
+
+  it("returns false when no processor matches a rewritten message", () => {
+    const registry = createServerRuleRegistry();
+
+    expect(registry.dispatch("chat_sync::client-a::{\"body\":\"hello\"}")).toBe(false);
+  });
+});
+
+describe("Yonexus.Server Auth Service", () => {
+  it("verifies valid auth request payload", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "test-pk";
+    record.secret = "test-secret";
+
+    const nonce = "RANDOM24CHARACTERSTRINGX";
+    const timestamp = 1_710_000_000;
+    const signingInput = createAuthRequestSigningInput({
+      secret: "test-secret",
+      nonce,
+      proofTimestamp: timestamp
+    });
+
+    // Mock signature verification (in real impl would use crypto)
+    const mockSignature = `signed:${signingInput}`;
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce,
+        proofTimestamp: timestamp,
+        signature: mockSignature,
+        publicKey: "test-pk"
+      },
+      {
+        now: () => timestamp,
+        verifySignature: (sig, input) => sig === `signed:${input}`
+      }
+    );
+
+    expect(result.success).toBe(true);
+    expect(result).toHaveProperty("authenticatedAt");
+  });
+
+  it("rejects auth for unpaired client", () => {
+    const record = createClientRecord("client-a");
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "RANDOM24CHARACTERSTRINGX",
+        proofTimestamp: 1_710_000_000,
+        signature: "sig",
+        publicKey: "pk"
+      },
+      { now: () => 1_710_000_000 }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("not_paired");
+  });
+
+  it("rejects auth with mismatched public key", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "expected-pk";
+    record.secret = "secret";
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "RANDOM24CHARACTERSTRINGX",
+        proofTimestamp: 1_710_000_000,
+        signature: "sig",
+        publicKey: "different-pk"
+      },
+      { now: () => 1_710_000_000 }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("public_key_mismatch");
+  });
+
+  it("rejects auth with stale timestamp", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "pk";
+    record.secret = "secret";
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "RANDOM24CHARACTERSTRINGX",
+        proofTimestamp: 1_710_000_000,
+        signature: "sig",
+        publicKey: "pk"
+      },
+      {
+        now: () => 1_710_000_100
+      }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("stale_timestamp");
+  });
+
+  it("rejects auth with future timestamp", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "pk";
+    record.secret = "secret";
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "RANDOM24CHARACTERSTRINGX",
+        proofTimestamp: 1_710_000_100,
+        signature: "sig",
+        publicKey: "pk"
+      },
+      { now: () => 1_710_000_000 }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("future_timestamp");
+  });
+
+  it("rejects auth with nonce collision", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "pk";
+    record.secret = "secret";
+    record.recentNonces = [{ nonce: "COLLIDING24CHARSTRINGX", timestamp: 1_710_000_000 }];
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "COLLIDING24CHARSTRINGX",
+        proofTimestamp: 1_710_000_010,
+        signature: "sig",
+        publicKey: "pk"
+      },
+      { now: () => 1_710_000_010 }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("nonce_collision");
+  });
+
+  it("rejects auth with rate limit exceeded", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "pk";
+    record.secret = "secret";
+    const now = 1_710_000_000;
+    record.recentHandshakeAttempts = Array(11).fill(now - 5);
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "RANDOM24CHARSTRINGX01",
+        proofTimestamp: now,
+        signature: "sig",
+        publicKey: "pk"
+      },
+      { now: () => now }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("rate_limited");
+  });
+
+  it("invalid signature triggers re_pair_required", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "pk";
+    record.secret = "secret";
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce: "RANDOM24CHARSTRINGX01",
+        proofTimestamp: 1_710_000_000,
+        signature: "invalid-sig",
+        publicKey: "pk"
+      },
+      {
+        now: () => 1_710_000_000,
+        verifySignature: () => false
+      }
+    );
+
+    expect(result.success).toBe(false);
+    expect(result.reason).toBe("re_pair_required");
+  });
+
+  it("tracks successful auth attempt in record", () => {
+    const record = createClientRecord("client-a");
+    record.pairingStatus = "paired";
+    record.publicKey = "pk";
+    record.secret = "secret";
+
+    const now = 1_710_000_000;
+    const nonce = "RANDOM24CHARSTRINGX01";
+
+    const signingInput = createAuthRequestSigningInput({
+      secret: "secret",
+      nonce,
+      proofTimestamp: now
+    });
+
+    const result = verifyAuthRequest(
+      record,
+      {
+        identifier: "client-a",
+        nonce,
+        proofTimestamp: now,
+        signature: `signed:${signingInput}`,
+        publicKey: "pk"
+      },
+      {
+        now: () => now,
+        verifySignature: (sig, input) => sig === `signed:${input}`
+      }
+    );
+
+    expect(result.success).toBe(true);
+    expect(record.recentNonces).toContainEqual({ nonce, timestamp: now });
+    expect(record.recentHandshakeAttempts).toContain(now);
+    expect(record.lastAuthenticatedAt).toBe(now);
+  });
+});
+
+describe("Yonexus.Server Heartbeat / Liveness", () => {
+  it("evaluates client online when recent heartbeat exists", () => {
+    const record = createClientRecord("client-a");
+    record.lastHeartbeatAt = 1_710_000_000;
+    record.status = "online";
+
+    const status = evaluateLiveness(record, { now: () => 1_710_000_300 });
+    expect(status).toBe("online");
+  });
+
+  it("evaluates client unstable after 7 minutes without heartbeat", () => {
+    const record = createClientRecord("client-a");
+    record.lastHeartbeatAt = 1_710_000_000;
+    record.status = "online";
+
+    const status = evaluateLiveness(record, { now: () => 1_710_000_420 });
+    expect(status).toBe("unstable");
+  });
+
+  it("evaluates client offline after 11 minutes without heartbeat", () => {
+    const record = createClientRecord("client-a");
+    record.lastHeartbeatAt = 1_710_000_000;
+    record.status = "online";
+
+    const status = evaluateLiveness(record, { now: () => 1_710_000_660 });
+    expect(status).toBe("offline");
+  });
+
+  it("handles client with no heartbeat record", () => {
+    const record = createClientRecord("client-a");
+
+    const status = evaluateLiveness(record, { now: () => 1_710_000_000 });
+    expect(status).toBe("offline");
+  });
+});
+
+function evaluateLiveness(
+  record: ReturnType<typeof createClientRecord>,
+  options: { now: () => number }
+): "online" | "unstable" | "offline" {
+  const now = options.now();
+  const lastHeartbeat = record.lastHeartbeatAt;
+
+  if (!lastHeartbeat) {
+    return "offline";
+  }
+
+  const elapsed = now - lastHeartbeat;
+
+  if (elapsed >= 11 * 60) {
+    return "offline";
+  }
+  if (elapsed >= 7 * 60) {
+    return "unstable";
+  }
+  return "online";
+}
+
+interface AuthRequestPayload {
+  identifier: string;
+  nonce: string;
+  proofTimestamp: number;
+  signature: string;
+  publicKey?: string;
+}
+
+interface AuthVerifyResult {
+  success: boolean;
+  reason?: string;
+  authenticatedAt?: number;
+}
+
+function verifyAuthRequest(
+  record: ClientRecord,
+  payload: AuthRequestPayload,
+  options: {
+    now: () => number;
+    verifySignature?: (signature: string, input: string) => boolean;
+  }
+): AuthVerifyResult {
+  if (record.pairingStatus !== "paired") {
+    return { success: false, reason: "not_paired" };
+  }
+
+  if (payload.publicKey && record.publicKey !== payload.publicKey) {
+    return { success: false, reason: "public_key_mismatch" };
+  }
+
+  const timestampCheck = isTimestampFresh(payload.proofTimestamp, options.now());
+  if (!timestampCheck.ok) {
+    return { success: false, reason: timestampCheck.reason };
+  }
+
+  const nonceCollision = record.recentNonces.some((n) => n.nonce === payload.nonce);
+  if (nonceCollision) {
+    return { success: false, reason: "nonce_collision" };
+  }
+
+  const now = options.now();
+  const recentAttempts = record.recentHandshakeAttempts.filter((t) => now - t < 10_000);
+  if (recentAttempts.length >= 10) {
+    return { success: false, reason: "rate_limited" };
+  }
+
+  const signingInput = createAuthRequestSigningInput({
+    secret: record.secret!,
+    nonce: payload.nonce,
+    proofTimestamp: payload.proofTimestamp
+  });
+
+  const isValidSignature = options.verifySignature?.(payload.signature, signingInput) ?? true;
+  if (!isValidSignature) {
+    return { success: false, reason: "re_pair_required" };
+  }
+
+  record.recentNonces.push({ nonce: payload.nonce, timestamp: now });
+  if (record.recentNonces.length > 10) {
+    record.recentNonces.shift();
+  }
+  record.recentHandshakeAttempts.push(now);
+  record.lastAuthenticatedAt = now;
+  record.lastHeartbeatAt = now;
+
+  return { success: true, authenticatedAt: now };
+}