Claude Code Hooks - Nexus Knowledge Base

Claude Code hooks provide automated enforcement of protocols and recovery from context compaction.

Configuration Location

Hooks are configured in: /.corsys/claude/settings.local.json

Hook Types

Event	Trigger	Use Case
SessionStart	startup, resume, compact	Load protocols after recovery
Stop	After Claude response	Enforce session agenda updates
PreToolUse	Before tool calls	Block/approve tools
PostToolUse	After tool completes	Validation, logging

Current Hooks

SessionStart Hook

Location: /opt/mcp-servers/shared/hooks/session_start_hook.py

Triggers on: startup|resume|compact

Purpose: - Outputs recovery reminder after auto-compact - Sets environment variables for session context - Forces Claude to read workflow.init

Stop Hook

Location: /opt/mcp-servers/shared/hooks/stop_hook.py

Purpose: - Runs after every Claude response - Future: Check if session agenda was updated - Future: Verify voice was used for responses - Can block stopping if protocols not followed

Hook Output Format

Hooks communicate via JSON:

{
  "decision": "approve" | "block",
  "reason": "Explanation",
  "continue": false,
  "systemMessage": "Warning to show"
}

block + reason = Claude must continue
stop_hook_active: true in input = prevent infinite loops

Settings Configuration

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "startup|resume|compact",
        "hooks": [
          {
            "type": "command",
            "command": "python3 /opt/mcp-servers/shared/hooks/session_start_hook.py",
            "timeout": 10
          }
        ]
      }
    ],
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "python3 /opt/mcp-servers/shared/hooks/stop_hook.py",
            "timeout": 5
          }
        ]
      }
    ]
  }
}

Settings file: /.corsys/claude/settings.local.json
Hook scripts: /opt/mcp-servers/shared/hooks/