sification and Triage Audit the existing configuration line-by-line. Categorize each constraint into one of three tiers:

• Mechanically Enforceable: Rules that can be validated through pattern matching, AST analysis, or environment checks. Examples include naming conventions, forbidden commands, file path restrictions, and formatting requirements.
• Judgment-Dependent: Rules requiring contextual reasoning, trade-off analysis, or stylistic adaptation. Examples include architectural preference weighting, user experience considerations, and migration cost evaluation.
• Aspirational/Redundant: Vague directives that do not alter behavior or duplicate existing tooling. These are candidates for immediate removal.

Step 2: Hook Architecture Implementation

Deterministic rules migrate to Claude Code's hook system. Hooks execute locally as discrete programs triggered by specific agent lifecycle events. Unlike prose, which the model attempts to follow, hooks enforce binary outcomes: the action proceeds or it is blocked with a structured error.

The hook architecture relies on four primary event types:

• PreToolUse: Executes before a tool call. Can inspect arguments and block execution.
• PostToolUse: Executes after tool completion. Useful for validation and cleanup.
• UserPromptSubmit: Fires when the user sends a message. Can rewrite or reject inputs.
• Stop: Triggers when the agent finishes a turn. Ideal for post-processing or logging.

Step 3: TypeScript Hook Implementation

Inline shell commands work for simple cases, but production environments benefit from typed, testable hook scripts. The following example demonstrates a TypeScript-based hook that prevents accidental commits to protected branches and validates that generated TypeScript files include strict type annotations.

Hook Script (hooks/validate-commit.ts):

import { execSync } from 'child_process';
import * as fs from 'fs';
import * as path from 'path';

interface HookInput {
  tool_name: string;
  input: Record<string, unknown>;
}

function isProtectedBranch(branch: string): boolean {
  const protectedPatterns = ['main', 'master', 'production', 'release/*'];
  return protectedPatterns.some(pattern => {
    const regex = new RegExp(`^${pattern.replace('*', '.*')}$`);
    return regex.test(branch);
  });
}

function checkStrictTypes(filePath: string): boolean {
  if (!filePath.endsWith('.ts') && !filePath.endsWith('.tsx')) return true;
  const content = fs.readFileSync(filePath, 'utf-8');
  const hasStrictAnnotations = /:\s*(string|number|boolean|any|unknown|void|never|[A-Z][a-zA-Z]*)/.test(content);
  return hasStrictAnnotations;
}

async function main() {
  const rawInput = process.env.CLAUDE_TOOL_INPUT || '{}';
  const payload: HookInput = JSON.parse(rawInput);

  if (payload.tool_name === 'Bash') {
    const command = String(payload.input.command || '');
    
    // Block commits to protected branches
    if (command.includes('git commit') || command.includes('git push')) {
      try {
        const currentBranch = execSync('git branch --show-current', { encoding: 'utf-8' }).trim();
        if (isProtectedBranch(currentBranch)) {
          console.error(`BLOCKED: Direct commits to ${currentBranch} are prohibited. Use feature branches.`);
          process.exit(2);
        }
      } catch {
        // Not a git repo or command failed; allow to proceed
      }
    }

    // Validate TypeScript strictness in generated files
    if (command.includes('cat >') || command.includes('tee ')) {
      const match = command.match(/(?:cat|tee)\s+.*?([\w./-]+\.(ts|tsx))/);
      if (match && match[1]) {
        const targetFile = match[1];
        if (fs.existsSync(targetFile) && !checkStrictTypes(targetFile)) {
          console.error(`BLOCKED: ${targetFile} lacks strict type annotations.`);
          process.exit(2);
        }
      }
    }
  }

  process.exit(0);
}

main().catch(err => {
  console.error('Hook execution failed:', err);
  process.exit(1);
});

Hook Configuration (claude_hooks.json):

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "npx tsx hooks/validate-commit.ts"
          }
        ]
      }
    ]
  }
}

Step 4: Prose Refinement

After extracting deterministic rules, rewrite the remaining configuration. Focus on explicit trade-off frameworks, architectural priorities, and contextual heuristics. Remove all aspirational language. Each line should answer a specific question the model cannot resolve through tooling alone.

Architecture Rationale

This separation exists because LLMs excel at pattern completion and trade-off analysis, but they are fundamentally probabilistic. They will occasionally miss buried instructions, especially when context windows contain competing signals. Hooks provide a deterministic boundary layer that guarantees compliance for safety-critical or workflow-enforcing rules. Static analysis tools (ESLint, Prettier, type checkers) handle language-specific formatting and syntax. Prose reserves its token budget for genuine reasoning tasks. This tri-layer architecture minimizes context pollution while maximizing reliability.

Pitfall Guide

1. Over-Hooking Legitimate Workflows

Explanation: Blocking commands too aggressively prevents the agent from performing necessary operations, causing frustration and workarounds. Fix: Implement allowlists for known-safe patterns. Use environment variables to toggle hook strictness between development and production contexts. Always log blocked attempts for audit trails.

2. Vague Prose Masquerading as Guidance

Explanation: Phrases like "write clean code" or "follow best practices" consume tokens but provide zero actionable constraints. The model interprets them inconsistently. Fix: Replace with explicit decision criteria. Instead of "optimize performance," use "prioritize O(n) algorithms over O(n²) when dataset size exceeds 10,000 records."

3. Ignoring Hook Execution Latency

Explanation: Complex hooks with heavy dependencies or network calls introduce noticeable delays before tool execution, degrading the interactive experience. Fix: Keep hooks lightweight. Use compiled binaries or pre-bundled scripts. Cache expensive checks. Set explicit timeout thresholds in the hook runner.

4. Hardcoding Absolute Paths

Explanation: Hooks that reference absolute filesystem paths break when repositories are cloned to different locations or run in CI environments. Fix: Use relative paths, environment variables ($PWD, $HOME), or resolve paths dynamically within the script. Validate path existence before execution.

5. Treating Hooks as CI/CD Replacements

Explanation: Hooks run locally and can be bypassed. Relying on them for production safety creates a false sense of security. Fix: Hooks are developer experience guardrails, not production enforcement. Mirror critical hook logic in CI/CD pipelines. Use hooks to catch mistakes early, not to replace formal validation stages.

6. Context Window Mismanagement

Explanation: Developers assume removing rules from prose automatically solves context issues, but forget that conversation history and repository indexing also consume tokens. Fix: Implement context window monitoring. Use chunking strategies for large codebases. Prioritize recent conversation turns and relevant file contents over historical context.

7. Hook State Leakage

Explanation: Hooks that modify environment variables or write to temporary files without cleanup can interfere with subsequent tool calls or agent turns. Fix: Ensure hooks are idempotent. Clean up temporary artifacts before exiting. Avoid mutating global state; pass data through structured outputs or environment variables scoped to the hook execution.

Production Bundle

Action Checklist

• Audit current configuration file and classify each line into deterministic, probabilistic, or aspirational categories
• Identify the top 10 most frequently violated deterministic rules and migrate them to hooks or linters
• Implement TypeScript-based hook scripts with explicit error handling and exit codes
• Remove all vague directives and consolidate redundant instructions
• Test hooks against common agent workflows to verify blocking behavior and false positive rates
• Document hook execution boundaries and fallback procedures for edge cases
• Schedule quarterly configuration reviews to prevent drift and token bloat

Decision Matrix

Scenario	Recommended Approach	Why	Cost Impact
Safety-critical command blocking	Deterministic Hooks	Binary enforcement prevents accidental destructive actions	Low (local execution)
Code style and formatting	Static Analysis/Linters	Standardized tooling with zero context overhead	Zero
Architectural trade-off guidance	Prose Configuration	Requires model reasoning and contextual weighting	Moderate (token consumption)
Workflow enforcement (branch protection, PR templates)	CI/CD Pipeline + Hooks	Hooks catch early, CI guarantees compliance	Low to Moderate
Performance optimization heuristics	Prose Configuration	Depends on dataset size, algorithm choice, and business constraints	Moderate

Configuration Template

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "npx tsx hooks/safety-guards.ts",
            "timeout_ms": 2000
          }
        ]
      },
      {
        "matcher": "Write",
        "hooks": [
          {
            "type": "command",
            "command": "npx tsx hooks/validate-output.ts",
            "timeout_ms": 1500
          }
        ]
      }
    ],
    "PostToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "npx tsx hooks/post-execution-log.ts",
            "timeout_ms": 1000
          }
        ]
      }
    ]
  }
}

Quick Start Guide

1. Initialize Hook Directory: Create a hooks/ folder in your project root. Add validate-commit.ts and safety-guards.ts using the patterns above.
2. Configure Event Triggers: Place the JSON configuration template in your project root or agent configuration directory. Adjust matchers to align with your tooling stack.
3. Install Dependencies: Run npm install -D tsx to enable TypeScript execution without compilation overhead.
4. Test Blocking Behavior: Trigger a protected command (e.g., git commit on main) and verify the hook returns exit code 2 with a clear error message.
5. Prune Prose: Remove migrated rules from your configuration file. Rewrite remaining lines to focus exclusively on judgment-dependent guidance. Verify token count drops below 200 lines.