diff --git a/__mocks__/obsidian.ts b/__mocks__/obsidian.ts
index e76eb02..6d94b71 100644
--- a/__mocks__/obsidian.ts
+++ b/__mocks__/obsidian.ts
@@ -1,11 +1,27 @@
 // Mock implementation of Obsidian API for Jest tests
 // This provides minimal implementations of the classes and types used in tests
 
+export interface MockPlugins {
+  plugins: Record<string, unknown>;
+}
+
+export interface MockCommands {
+  commands: Record<string, unknown>;
+}
+
+export interface MockVault {
+  [key: string]: unknown;
+}
+
+export interface MockWorkspace {
+  [key: string]: unknown;
+}
+
 export class App {
-  plugins: any;
-  commands: any;
-  vault: any;
-  workspace: any;
+  plugins: MockPlugins;
+  commands: MockCommands;
+  vault: MockVault;
+  workspace: MockWorkspace;
   
   constructor() {
     this.plugins = {
@@ -19,9 +35,13 @@ export class App {
   }
 }
 
+export interface MockSettings {
+  [key: string]: unknown;
+}
+
 export class Plugin {
   app: App;
-  settings: any;
+  settings: MockSettings;
   
   constructor(app: App) {
     this.app = app;
@@ -51,9 +71,18 @@ export class TFolder {
   }
 }
 
+export interface MockView {
+  getViewType: () => string;
+  [key: string]: unknown;
+}
+
+export interface MockViewState {
+  [key: string]: unknown;
+}
+
 export class WorkspaceLeaf {
-  view: any;
-  viewState: any;
+  view: MockView;
+  viewState: MockViewState;
   
   constructor() {
     this.view = {
@@ -62,7 +91,7 @@ export class WorkspaceLeaf {
     this.viewState = {};
   }
   
-  async setViewState(state: any): Promise<void> {
+  async setViewState(state: MockViewState): Promise<void> {
     this.viewState = state;
   }
   
diff --git a/src/shared/error-handler.ts b/src/shared/error-handler.ts
index 3cc2a94..cbe3310 100644
--- a/src/shared/error-handler.ts
+++ b/src/shared/error-handler.ts
@@ -4,11 +4,12 @@
 
 import { eventBus, EVENTS } from './event-bus';
 import { centralizedLogger } from './centralized-logger';
+import { ErrorData } from './types';
 
 export interface ErrorContext {
     service: string;
     method: string;
-    data?: any;
+    data?: ErrorData;
     timestamp: number;
 }
 
@@ -74,7 +75,7 @@ export class ErrorHandler {
                         this.handleError(error, {
                             service,
                             method,
-                            data: args,
+                            data: { args },
                             timestamp: Date.now()
                         });
                         throw error;
@@ -86,7 +87,7 @@ export class ErrorHandler {
                 this.handleError(error as Error, {
                     service,
                     method,
-                    data: args,
+                    data: { args },
                     timestamp: Date.now()
                 });
                 throw error;
@@ -107,7 +108,7 @@ export class ErrorHandler {
                 this.handleError(error, {
                     service,
                     method,
-                    data: args,
+                    data: { args },
                     timestamp: Date.now()
                 });
                 throw error;
@@ -138,7 +139,7 @@ export class ErrorHandler {
 export const errorHandler = ErrorHandler.getInstance();
 
 // Utility function for easy error handling
-export function handleError(error: Error, service: string, method: string, data?: any): void {
+export function handleError(error: Error, service: string, method: string, data?: ErrorData): void {
     errorHandler.handleError(error, {
         service,
         method,
diff --git a/src/shared/event-bus.ts b/src/shared/event-bus.ts
index 59fe8eb..6a97da8 100644
--- a/src/shared/event-bus.ts
+++ b/src/shared/event-bus.ts
@@ -4,10 +4,11 @@
  */
 
 import { centralizedLogger } from './centralized-logger';
+import { EventData } from './types';
 
 export interface EventBusEvent {
     type: string;
-    data?: any;
+    data?: EventData;
     timestamp: number;
     source: string;
 }
@@ -44,7 +45,7 @@ export class EventBus {
     /**
      * Emit an event
      */
-    emit(eventType: string, data?: any, source: string = 'unknown'): void {
+    emit(eventType: string, data?: EventData, source: string = 'unknown'): void {
         const event: EventBusEvent = {
             type: eventType,
             data,
diff --git a/src/shared/performance-monitor.ts b/src/shared/performance-monitor.ts
index a12bdfd..9f5db2c 100644
--- a/src/shared/performance-monitor.ts
+++ b/src/shared/performance-monitor.ts
@@ -2,11 +2,17 @@
  * Performance Monitoring System
  */
 
+import { ErrorData } from './types';
+
+export interface PerformanceMetadata {
+    [key: string]: unknown;
+}
+
 export interface PerformanceMetric {
     name: string;
     duration: number;
     timestamp: number;
-    metadata?: any;
+    metadata?: PerformanceMetadata;
 }
 
 export class PerformanceMonitor {
@@ -41,7 +47,7 @@ export class PerformanceMonitor {
     /**
      * Record a performance metric
      */
-    recordMetric(name: string, duration: number, metadata?: any): void {
+    recordMetric(name: string, duration: number, metadata?: PerformanceMetadata): void {
         if (!this.isEnabled) return;
 
         this.metrics.push({
@@ -63,7 +69,7 @@ export class PerformanceMonitor {
     measure<T extends (...args: any[]) => any>(
         fn: T,
         name: string,
-        metadata?: any
+        metadata?: PerformanceMetadata
     ): T {
         return ((...args: any[]) => {
             const endTiming = this.startTiming(name);
@@ -92,7 +98,7 @@ export class PerformanceMonitor {
     measureAsync<T extends (...args: any[]) => Promise<any>>(
         fn: T,
         name: string,
-        metadata?: any
+        metadata?: PerformanceMetadata
     ): T {
         return ((...args: any[]) => {
             const endTiming = this.startTiming(name);
@@ -177,7 +183,7 @@ export const performanceMonitor = PerformanceMonitor.getInstance();
 export function measurePerformance<T extends (...args: any[]) => any>(
     fn: T,
     name: string,
-    metadata?: any
+    metadata?: PerformanceMetadata
 ): T {
     return performanceMonitor.measure(fn, name, metadata);
 }
@@ -185,7 +191,7 @@ export function measurePerformance<T extends (...args: any[]) => any>(
 export function measureAsyncPerformance<T extends (...args: any[]) => Promise<any>>(
     fn: T,
     name: string,
-    metadata?: any
+    metadata?: PerformanceMetadata
 ): T {
     return performanceMonitor.measureAsync(fn, name, metadata);
 }
diff --git a/src/shared/types.ts b/src/shared/types.ts
index ac50d72..fb6bc73 100644
--- a/src/shared/types.ts
+++ b/src/shared/types.ts
@@ -35,3 +35,41 @@ export interface StreamsSettings {
     debugLoggingEnabled: boolean; // Whether debug logging is enabled by default
     barStyle: 'default' | 'modern'; // Style variant for the streams bar
 }
+
+// Event Data Types for type-safe event payloads
+export type EventData =
+    // Stream events
+    | { stream: Stream } // STREAM_ADDED, STREAM_UPDATED
+    | { streamId: string } // STREAM_REMOVED
+    | { streamId: string; previousStreamId?: string } // ACTIVE_STREAM_CHANGED
+    | { streamId: string; disabled: boolean } // STREAM_UPDATED (disabled state)
+
+    // Settings events
+    | StreamsSettings // SETTINGS_CHANGED
+
+    // UI events
+    | { component: string } // CALENDAR_COMPONENT_UPDATED, RIBBON_ICONS_UPDATED
+
+    // File events
+    | { filePath: string } // FILE_OPENED, FILE_CREATED
+
+    // Plugin events
+    | { plugin: any } // PLUGIN_LOADED, PLUGIN_UNLOADED (using any for Obsidian plugin type)
+
+    // Error events
+    | { error: Error; service: string; method: string; data?: ErrorData } // ERROR_OCCURRED
+
+    // Date events
+    | { date: Date; monthView?: Date } // date-changed
+
+    // View events
+    | any; // Fallback for custom view events
+
+// Error Data Types for type-safe error context
+export interface ErrorData {
+    [key: string]: unknown;
+}
+
+// Log Types for type-safe logging
+export type LogMessage = string | number | boolean | null | undefined;
+export type LogParams = (LogMessage | object | Error)[];
diff --git a/src/slices/calendar-navigation/CalendarNavigationService.ts b/src/slices/calendar-navigation/CalendarNavigationService.ts
index 6ea2c93..68a3793 100644
--- a/src/slices/calendar-navigation/CalendarNavigationService.ts
+++ b/src/slices/calendar-navigation/CalendarNavigationService.ts
@@ -204,9 +204,9 @@ export class CalendarNavigationService extends SettingsAwareSliceService impleme
 
     public updateAllStreamsBarComponents = measurePerformance((): void => {
         if (this.isInitializing) return;
-        
+
         this.refreshStreamsBarComponentsForNewViews();
-    }, 'calendar-navigation', 'updateAllStreamsBarComponents');
+    }, 'calendar-navigation', { operation: 'updateAllStreamsBarComponents' });
 
     public refreshAllStreamsBarComponents(): void {
         this.refreshStreamsBarComponentsForNewViews();
diff --git a/src/slices/debug-logging/Logger.ts b/src/slices/debug-logging/Logger.ts
index cb121b2..7c0c9a6 100644
--- a/src/slices/debug-logging/Logger.ts
+++ b/src/slices/debug-logging/Logger.ts
@@ -1,3 +1,5 @@
+import { LogMessage, LogParams } from '../../shared/types';
+
 export enum LogLevel {
     ERROR = 0,
     WARN = 1,
@@ -66,28 +68,28 @@ export class Logger {
     }
 
 
-    debug(message?: any, ...optionalParams: any[]): void {
+    debug(message?: LogMessage, ...optionalParams: LogParams): void {
         if (!this.enabled || this.level > LogLevel.DEBUG) {
             return;
         }
         console.debug(this.prefix + message, ...optionalParams);
     }
 
-    info(message?: any, ...optionalParams: any[]): void {
+    info(message?: LogMessage, ...optionalParams: LogParams): void {
         if (!this.enabled || this.level > LogLevel.INFO) {
             return;
         }
         console.log(this.prefix + message, ...optionalParams);
     }
 
-    warn(message?: any, ...optionalParams: any[]): void {
+    warn(message?: LogMessage, ...optionalParams: LogParams): void {
         if (!this.enabled || this.level > LogLevel.WARN) {
             return;
         }
         console.warn(this.prefix + message, ...optionalParams);
     }
 
-    error(message?: any, ...optionalParams: any[]): void {
+    error(message?: LogMessage, ...optionalParams: LogParams): void {
         if (!this.enabled || this.level > LogLevel.ERROR) {
             return;
         }
@@ -95,7 +97,7 @@ export class Logger {
     }
 
 
-    trace(message?: any, ...optionalParams: any[]): void {
+    trace(message?: LogMessage, ...optionalParams: LogParams): void {
         if (this.enabled) {
             console.trace(this.prefix + message, ...optionalParams);
         }
@@ -113,7 +115,7 @@ export class Logger {
         }
     }
 
-    table(tabularData: any, properties?: string[]): void {
+    table(tabularData: unknown, properties?: string[]): void {
         if (this.enabled) {
             console.table(tabularData, properties);
         }