Hooks in Claude Code — Full Theory + Practical Use | CampusX

In this video, we deeply explore Hooks in Claude Code and understand why they are essential for building safe and reliable AI coding workflows. The video explains the internal architecture of Claude Code, the concept of coding harnesses, agent loops, session lifecycle, and how hooks help enforce deterministic behaviour in probabilistic AI systems. You’ll also learn practical use cases like preventing dangerous file operations, automating workflows, and improving reliability in production-grade projects. 📱 Grow with us: CampusX' LinkedIn: https://www.linkedin.com/company/campusx-official CampusX on Instagram for daily tips: https://www.instagram.com/campusx.official My LinkedIn: https://www.linkedin.com/in/nitish-singh-03412789 Discord: https://discord.gg/PsWu8R87Z8 E-mail us at [email protected] 0:00 - Introduction 0:41 - Why Hooks Exist (Problem First Approach) 1:12 - What is Claude Code Internally? 2:00 - Claude Code as an Agentic Coding System 4:22 - Understanding Coding Harness (Core Concept) 7:00 - LLM Limitations & Why Harnesses Matter 8:31 - What a Coding Harness Actually Does 11:24 - How Coding Harness & LLM Work Together 13:31 - Harness Engineering & Emerging Ecosystem 15:31 - Core Problem: Probabilistic LLM + Deterministic Harness 17:48 - Risks in Real Projects (File Deletion, Unsafe Actions) 19:10 - Why Instructions in claude.md Are Not Enough 20:53 - Agent Loop Explained (How Claude Executes Tasks) 24:48 - Session Lifecycle Explained 27:27 - Events Inside Claude Code Lifecycle 30:05 - What are Hooks? (Core Definition) 31:01 - Practical Example: Preventing Dangerous Operations 33:35 - How Hooks Make AI Systems Deterministic 34:37 - Common Use Cases of Hooks (Formatting, Safety, Automation) 36:01 - Hooks for Auto Formatting & Code Consistency 37:53 - Linting Hooks (Bug Detection & Code Quality) 39:29 - Security Hooks (Blocking Dangerous Commands & Protecting Files) 40:13 - Notification Hooks (Task Completion Alerts) 41:13 - Telemetry Hooks (Monitoring Subagents & Events) 42:13 - Personal Workflow Automation with Hooks 43:11 - Internal Working of Hooks (Events, Matchers, Actions) 45:31 - Building a File Protection Hook (Practical Example) 46:49 - Complete Hook Execution Flow Explained 49:09 - Live Demo: Preventing Database Deletion 52:11 - Creating Real Hooks (Formatter + Sensitive File Protection) 54:29 - Integrating Hooks into Real Project Workflow 55:31 - Building “Edit Expense” Feature with Claude Code 57:01 - Testing & Verifying the Feature 58:27 - MCP + GitHub Workflow Integration 59:07 - Fixing GitHub Token Permissions 1:00:07 - Creating “Ship Feature” Custom Command