diff --git a/src/client/GuildPassClient.ts b/src/client/GuildPassClient.ts
index d10bd92..37509a2 100644
--- a/src/client/GuildPassClient.ts
+++ b/src/client/GuildPassClient.ts
@@ -24,6 +24,7 @@ import type { AccessCheckParams, RoleAccessCheckParams, AccessCheckBatchOptions,
 import type { MembershipParams } from '../membership/membership.types';
 import type { GetRolesParams, GetUserRolesParams, HasRoleParams } from '../roles/roles.types';
 import type { GetGuildParams } from '../guilds/guilds.types';
+import { DiagnosticsModule } from '../diagnostics/DiagnosticsModule';
 
 /**
  * The main GuildPass SDK this.
@@ -84,6 +85,7 @@ export class GuildPassClient {
   public readonly guilds: GuildsService;
   // GuildPass SDK: Class member structure property or constructor.
   public readonly contracts: ContractClient;
+  public readonly diagnostics: DiagnosticsModule;
 
   // GuildPass SDK: Class member structure property or constructor.
   private readonly http: HttpClient;
@@ -162,6 +164,38 @@ export class GuildPassClient {
     this.roles = this.buildCachedRolesService(rawRoles);
     this.guilds = this.buildCachedGuildsService(rawGuilds);
     this.contracts = rawContracts;
+
+    this.diagnostics = new DiagnosticsModule();
+    this.diagnostics.registerInFlightRequests(() => this.inFlightRequests.size);
+    this.diagnostics.registerRateLimit(() => this.http.getRateLimitStatus());
+    this.diagnostics.registerCircuitBreakers(() => this.contracts.getCircuitBreakerSnapshot());
+
+    // Hook up rate limit events if token bucket exists
+    if (this.config.rateLimit) {
+      const originalOnThrottled = (this.config.rateLimit as any).onThrottled;
+      (this.config.rateLimit as any).onThrottled = (until: number) => {
+        this.diagnostics.emit('rateLimitThrottled', { throttlingUntil: until });
+        if (originalOnThrottled) originalOnThrottled(until);
+      };
+    }
+
+    // Hook up circuit breaker events if using adaptive provider
+    if (this.config.contractProvider && (this.config.contractProvider as any).healthTracker) {
+      const tracker = (this.config.contractProvider as any).healthTracker;
+      if (tracker && tracker.config) {
+        const originalOnCircuitOpen = tracker.config.onCircuitOpen;
+        const originalOnCircuitClosed = tracker.config.onCircuitClosed;
+        tracker.config.onCircuitOpen = (url: string, until: number) => {
+          this.diagnostics.emit('circuitOpen', { url, openUntil: until });
+          if (originalOnCircuitOpen) originalOnCircuitOpen(url, until);
+        };
+        tracker.config.onCircuitClosed = (url: string) => {
+          this.diagnostics.emit('circuitClosed', { url });
+          if (originalOnCircuitClosed) originalOnCircuitClosed(url);
+        };
+      }
+    }
+
     // GuildPass SDK: End of logic containment structure block.
   }
 
@@ -318,11 +352,17 @@ export class GuildPassClient {
     if (this.cache) {
       try {
         const cached = await this.cache.get<T>(key);
-        if (cached !== null) return cached;
+        if (cached !== null) {
+          this.diagnostics.recordCacheHit(key);
+          return cached;
+        }
       } catch (error: any) {
+        this.diagnostics.recordCacheError();
         this.handleCacheError('get', error, key);
       }
     }
+    
+    this.diagnostics.recordCacheMiss(key);
 
     const execute = async (): Promise<T> => {
       const result = await fn();
diff --git a/src/contracts/contractClient.ts b/src/contracts/contractClient.ts
index a8ee7e0..3b2a165 100644
--- a/src/contracts/contractClient.ts
+++ b/src/contracts/contractClient.ts
@@ -719,6 +719,16 @@ export class ContractClient {
     return result;
   }
 
+  public getCircuitBreakerSnapshot(): Record<string, any> {
+    // ContractClient doesn't hold the AdaptiveContractProvider directly if it is passed in,
+    // but we can check if the contractProvider is AdaptiveContractProvider and has healthTracker.
+    const provider = this.config.contractProvider as any;
+    if (provider && provider.healthTracker && typeof provider.healthTracker.snapshotAll === 'function') {
+      return provider.healthTracker.snapshotAll();
+    }
+    return {};
+  }
+
   /**
    * Fetches the owner of a guild from the contract.
    *
diff --git a/src/contracts/providers/adaptive.types.ts b/src/contracts/providers/adaptive.types.ts
index 5d526fc..a739a4a 100644
--- a/src/contracts/providers/adaptive.types.ts
+++ b/src/contracts/providers/adaptive.types.ts
@@ -49,6 +49,10 @@ export type AdaptiveHealthConfig = {
   failureThreshold?: number;
   /** How long the circuit stays open before a trial call, ms. Default: 30000. */
   cooldownMs?: number;
+  /** Callback fired when a circuit breaker opens. */
+  onCircuitOpen?: (url: string, openUntil: number) => void;
+  /** Callback fired when a circuit breaker closes. */
+  onCircuitClosed?: (url: string) => void;
   /** Smoothing factor for the latency EMA, between 0 and 1. Default: 0.3. */
   latencyEmaAlpha?: number;
   /** Batch size at or above which Multicall3 is strongly preferred. Default: 3. */
diff --git a/src/contracts/providers/healthTracker.ts b/src/contracts/providers/healthTracker.ts
index c7ec3ce..32949e0 100644
--- a/src/contracts/providers/healthTracker.ts
+++ b/src/contracts/providers/healthTracker.ts
@@ -1,7 +1,10 @@
 // GuildPass SDK: Pull in package or module bindings.
 import { AdaptiveHealthConfig, UrlHealth } from './adaptive.types';
 
-const DEFAULTS: Required<AdaptiveHealthConfig> = {
+const DEFAULTS: Omit<Required<AdaptiveHealthConfig>, 'onCircuitOpen' | 'onCircuitClosed'> & {
+  onCircuitOpen?: (url: string, openUntil: number) => void;
+  onCircuitClosed?: (url: string) => void;
+} = {
   failureThreshold: 3,
   cooldownMs: 30000,
   latencyEmaAlpha: 0.3,
@@ -24,7 +27,10 @@ const DEFAULTS: Required<AdaptiveHealthConfig> = {
  * response does not dominate routing decisions.
  */
 export class HealthTracker {
-  private readonly config: Required<AdaptiveHealthConfig>;
+  private readonly config: Omit<Required<AdaptiveHealthConfig>, 'onCircuitOpen' | 'onCircuitClosed'> & {
+    onCircuitOpen?: (url: string, openUntil: number) => void;
+    onCircuitClosed?: (url: string) => void;
+  };
   private readonly health = new Map<string, UrlHealth>();
 
   constructor(config?: AdaptiveHealthConfig) {
@@ -56,6 +62,9 @@ export class HealthTracker {
     if (record.circuitOpen && now >= record.openUntil) {
       // Cooldown elapsed: allow a half-open trial call through.
       record.circuitOpen = false;
+      if (this.config.onCircuitClosed) {
+        this.config.onCircuitClosed(url);
+      }
     }
     return !record.circuitOpen;
   }
@@ -63,6 +72,7 @@ export class HealthTracker {
   /** Records a successful call: resets failures and updates latency EMA. */
   public recordSuccess(url: string, latencyMs: number): void {
     const record = this.get(url);
+    const wasOpen = record.circuitOpen;
     record.consecutiveFailures = 0;
     record.circuitOpen = false;
     record.openUntil = 0;
@@ -71,6 +81,10 @@ export class HealthTracker {
         ? latencyMs
         : this.config.latencyEmaAlpha * latencyMs +
           (1 - this.config.latencyEmaAlpha) * record.latencyEmaMs;
+
+    if (wasOpen && this.config.onCircuitClosed) {
+      this.config.onCircuitClosed(url);
+    }
   }
 
   /**
@@ -80,9 +94,12 @@ export class HealthTracker {
   public recordFailure(url: string, now: number = Date.now()): void {
     const record = this.get(url);
     record.consecutiveFailures += 1;
-    if (record.consecutiveFailures >= this.config.failureThreshold) {
+    if (!record.circuitOpen && record.consecutiveFailures >= this.config.failureThreshold) {
       record.circuitOpen = true;
       record.openUntil = now + this.config.cooldownMs;
+      if (this.config.onCircuitOpen) {
+        this.config.onCircuitOpen(url, record.openUntil);
+      }
     }
   }
 
@@ -102,4 +119,12 @@ export class HealthTracker {
     const record = this.health.get(url);
     return record ? { ...record } : undefined;
   }
+
+  public snapshotAll(): Record<string, Readonly<UrlHealth>> {
+    const result: Record<string, Readonly<UrlHealth>> = {};
+    for (const [url, record] of this.health.entries()) {
+      result[url] = { ...record };
+    }
+    return result;
+  }
 }
diff --git a/src/diagnostics/DiagnosticsModule.ts b/src/diagnostics/DiagnosticsModule.ts
new file mode 100644
index 0000000..cebea40
--- /dev/null
+++ b/src/diagnostics/DiagnosticsModule.ts
@@ -0,0 +1,75 @@
+import {
+  CacheDiagnostics,
+  CircuitBreakerDiagnostics,
+  DiagnosticsEvents,
+  DiagnosticsSnapshot,
+  RateLimitDiagnostics,
+} from './diagnostics.types';
+
+export class DiagnosticsModule {
+  private cacheStats: CacheDiagnostics = { hits: 0, misses: 0, errors: 0 };
+  private listeners: Record<string, Set<any>> = {};
+
+  private inFlightRequestsProvider?: () => number;
+  private rateLimitProvider?: () => RateLimitDiagnostics | null;
+  private circuitBreakersProvider?: () => Record<string, CircuitBreakerDiagnostics>;
+
+  public on<K extends keyof DiagnosticsEvents>(event: K, handler: DiagnosticsEvents[K]): void {
+    if (!this.listeners[event as string]) {
+      this.listeners[event as string] = new Set();
+    }
+    this.listeners[event as string].add(handler);
+  }
+
+  public off<K extends keyof DiagnosticsEvents>(event: K, handler: DiagnosticsEvents[K]): void {
+    if (this.listeners[event as string]) {
+      this.listeners[event as string].delete(handler);
+    }
+  }
+
+  public emit<K extends keyof DiagnosticsEvents>(
+    event: K,
+    ...args: Parameters<DiagnosticsEvents[K]>
+  ): void {
+    if (this.listeners[event as string]) {
+      for (const handler of this.listeners[event as string]) {
+        handler(...args);
+      }
+    }
+  }
+
+  public registerInFlightRequests(fn: () => number): void {
+    this.inFlightRequestsProvider = fn;
+  }
+
+  public registerRateLimit(fn: () => RateLimitDiagnostics | null): void {
+    this.rateLimitProvider = fn;
+  }
+
+  public registerCircuitBreakers(fn: () => Record<string, CircuitBreakerDiagnostics>): void {
+    this.circuitBreakersProvider = fn;
+  }
+
+  public recordCacheHit(key: string): void {
+    this.cacheStats.hits++;
+    this.emit('cacheHit', { key });
+  }
+
+  public recordCacheMiss(key: string): void {
+    this.cacheStats.misses++;
+    this.emit('cacheMiss', { key });
+  }
+
+  public recordCacheError(): void {
+    this.cacheStats.errors++;
+  }
+
+  public getSnapshot(): DiagnosticsSnapshot {
+    return {
+      inFlightRequests: this.inFlightRequestsProvider ? this.inFlightRequestsProvider() : 0,
+      cache: { ...this.cacheStats },
+      rateLimit: this.rateLimitProvider ? this.rateLimitProvider() : null,
+      circuitBreakers: this.circuitBreakersProvider ? this.circuitBreakersProvider() : {},
+    };
+  }
+}
diff --git a/src/diagnostics/diagnostics.types.ts b/src/diagnostics/diagnostics.types.ts
new file mode 100644
index 0000000..3545313
--- /dev/null
+++ b/src/diagnostics/diagnostics.types.ts
@@ -0,0 +1,32 @@
+export interface CacheDiagnostics {
+  hits: number;
+  misses: number;
+  errors: number;
+}
+
+export interface CircuitBreakerDiagnostics {
+  circuitOpen: boolean;
+  consecutiveFailures: number;
+  latencyEmaMs: number;
+  openUntil: number;
+}
+
+export interface RateLimitDiagnostics {
+  throttlingUntil: number;
+  currentRate: number;
+}
+
+export interface DiagnosticsSnapshot {
+  inFlightRequests: number;
+  cache: CacheDiagnostics;
+  rateLimit: RateLimitDiagnostics | null;
+  circuitBreakers: Record<string, CircuitBreakerDiagnostics>;
+}
+
+export interface DiagnosticsEvents {
+  circuitOpen: (data: { url: string; openUntil: number }) => void;
+  circuitClosed: (data: { url: string }) => void;
+  rateLimitThrottled: (data: { throttlingUntil: number }) => void;
+  cacheHit: (data: { key: string }) => void;
+  cacheMiss: (data: { key: string }) => void;
+}
diff --git a/src/diagnostics/index.ts b/src/diagnostics/index.ts
new file mode 100644
index 0000000..07b321a
--- /dev/null
+++ b/src/diagnostics/index.ts
@@ -0,0 +1,2 @@
+export * from './diagnostics.types';
+export * from './DiagnosticsModule';
diff --git a/src/http/httpClient.ts b/src/http/httpClient.ts
index 5a544c5..f7939ef 100644
--- a/src/http/httpClient.ts
+++ b/src/http/httpClient.ts
@@ -471,4 +471,12 @@ export class HttpClient {
       }
     }
   }
+
+  public getRateLimitStatus(): { throttlingUntil: number; currentRate: number } | null {
+    if (!this.tokenBucket) return null;
+    return {
+      throttlingUntil: this.tokenBucket.getThrottlingUntil(),
+      currentRate: this.tokenBucket.getCurrentRate(),
+    };
+  }
 }
\ No newline at end of file
diff --git a/src/http/tokenBucket.ts b/src/http/tokenBucket.ts
index 63f1940..4f2cb51 100644
--- a/src/http/tokenBucket.ts
+++ b/src/http/tokenBucket.ts
@@ -1,6 +1,7 @@
 export type RateLimitConfig = {
   requestsPerSecond: number;
   burst?: number;
+  onThrottled?: (throttlingUntil: number) => void;
 };
 
 function delay(ms: number): Promise<void> {
@@ -16,7 +17,10 @@ export class TokenBucket {
   private lastRefill: number;
   private retryUntil: number = 0; // Timestamp until which requests are throttled
 
+  private config: RateLimitConfig;
+
   constructor(config: RateLimitConfig) {
+    this.config = config;
     const { requestsPerSecond, burst } = config;
     this.baseRate = requestsPerSecond;
     this.currentRate = requestsPerSecond;
@@ -66,6 +70,10 @@ export class TokenBucket {
     if (this.currentRate < 0.01) this.currentRate = 0.01;
     this.refillRate = this.currentRate / 1000;
     this.tokens = Math.min(this.tokens, this.capacity);
+    
+    if (this.config.onThrottled) {
+      this.config.onThrottled(this.retryUntil);
+    }
   }
 
   onSuccess(): void {
@@ -78,4 +86,8 @@ export class TokenBucket {
   public getThrottlingUntil(): number {
     return this.retryUntil > Date.now() ? this.retryUntil : 0;
   }
+
+  public getCurrentRate(): number {
+    return this.currentRate;
+  }
 }
\ No newline at end of file
diff --git a/src/testing/mockClient.ts b/src/testing/mockClient.ts
index 81aadfc..9b1e833 100644
--- a/src/testing/mockClient.ts
+++ b/src/testing/mockClient.ts
@@ -6,6 +6,7 @@ import { RolesService } from '../roles/roles.service';
 import { ContractClient } from '../contracts/contractClient';
 import { DEFAULT_ACCESS_RESULT, DEFAULT_GUILD, DEFAULT_GUILD_CONFIG, DEFAULT_ROLE, DEFAULT_MEMBERSHIP } from './fixtures';
 import type { PublicClientConfig } from '../config/sdkConfig';
+import { DiagnosticsModule } from '../diagnostics/DiagnosticsModule';
 
 /** 
  * Utility type to extract only the public properties and methods of a class.
@@ -87,6 +88,7 @@ export function createMockGuildPassClient(overrides?: MockClientOverrides): Guil
     invalidateWalletCache: async () => {},
     clearCache: async () => {},
     getConfig: overrides?.getConfig ?? (() => ({ apiUrl: 'https://mock.guildpass.xyz' })),
+    diagnostics: new DiagnosticsModule(),
   };
 
   // Cast safely. TypeScript guarantees that `mockClientPublic` shapes up to the public interface.
diff --git a/tests/diagnostics.test.ts b/tests/diagnostics.test.ts
new file mode 100644
index 0000000..3436b46
--- /dev/null
+++ b/tests/diagnostics.test.ts
@@ -0,0 +1,64 @@
+import { describe, it, expect, vi } from 'vitest';
+import { GuildPassClient, InMemoryCacheAdapter, AdaptiveContractProvider } from '../src';
+
+describe('DiagnosticsModule', () => {
+  it('should expose a unified snapshot with at least three operational states', async () => {
+    const cache = new InMemoryCacheAdapter();
+    const adaptiveProvider = new AdaptiveContractProvider({
+      post: async () => ({ data: '0x' })
+    } as any, ['http://rpc1.test']);
+
+    const client = new GuildPassClient({
+      apiUrl: 'https://api.test',
+      cache,
+      contractProvider: adaptiveProvider,
+      rateLimit: { requestsPerSecond: 10 },
+    });
+
+    // Manually simulate in-flight requests to test the wiring
+    (client as any).inFlightRequests.set('dummy1', Promise.resolve());
+    (client as any).inFlightRequests.set('dummy2', Promise.resolve());
+
+    const snap1 = client.diagnostics.getSnapshot();
+    expect(snap1.inFlightRequests).toBe(2);
+
+    // Simulate cache hit/miss to test wiring
+    client.diagnostics.recordCacheHit('dummy');
+    client.diagnostics.recordCacheMiss('dummy2');
+    client.diagnostics.recordCacheMiss('dummy3');
+
+    const snap2 = client.diagnostics.getSnapshot();
+    expect(snap2.cache.hits).toBe(1);
+    expect(snap2.cache.misses).toBe(2);
+
+    // Rate limit
+    expect(snap2.rateLimit).not.toBeNull();
+    expect(snap2.rateLimit?.currentRate).toBeDefined();
+
+    // Circuit breakers
+    expect(snap2.circuitBreakers).toBeDefined();
+  });
+
+  it('should fire event emitter correctly for state transitions', async () => {
+    const adaptiveProvider = new AdaptiveContractProvider({
+      post: async () => ({ data: '0x' })
+    } as any, ['http://rpc.test'], { health: { failureThreshold: 1, cooldownMs: 5000 } });
+
+    const client = new GuildPassClient({
+      apiUrl: 'https://api.test',
+      contractProvider: adaptiveProvider,
+    });
+
+    const onCircuitOpen = vi.fn();
+    client.diagnostics.on('circuitOpen', onCircuitOpen);
+
+    // Manually trip the circuit breaker on the health tracker
+    const tracker = (adaptiveProvider as any).healthTracker;
+    tracker.recordFailure('http://rpc.test', Date.now());
+
+    expect(onCircuitOpen).toHaveBeenCalled();
+    const eventArg = onCircuitOpen.mock.calls[0][0];
+    expect(eventArg.url).toBe('http://rpc.test');
+    expect(eventArg.openUntil).toBeGreaterThan(Date.now());
+  });
+});