Terraphim Hooks

Use this skill when setting up or using Terraphim's knowledge graph-based text replacement capabilities through hooks.

Overview

Terraphim hooks intercept text at key points (CLI commands, commit messages) and apply transformations using Aho-Corasick automata built from knowledge graph definitions.

Key Components:

• terraphim-agent replace - CLI command for text replacement
• PreToolUse hooks - Intercept Claude Code tool calls before execution
• Git hooks - Transform commit messages using prepare-commit-msg

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                     Knowledge Graph (docs/src/kg/)              │
│  ┌──────────────┐  ┌──────────────────┐  ┌──────────────────┐  │
│  │ bun.md       │  │ bun_install.md   │  │ terraphim_ai.md  │  │
│  │ synonyms::   │  │ synonyms::       │  │ synonyms::       │  │
│  │ npm, yarn,   │  │ npm install,     │  │ Claude Code,     │  │
│  │ pnpm, npx    │  │ yarn install...  │  │ Claude Opus...   │  │
│  └──────────────┘  └──────────────────┘  └──────────────────┘  │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
              ┌───────────────────────────────┐
              │   Aho-Corasick Automata       │
              │   (LeftmostLongest matching)  │
              └───────────────────────────────┘
                              │
              ┌───────────────┴───────────────┐
              │                               │
              ▼                               ▼
   ┌──────────────────────┐       ┌──────────────────────┐
   │  PreToolUse Hook     │       │  Git Hook            │
   │  (npm → bun)         │       │  (Claude → Terraphim)│
   │                      │       │                      │
   │  Input: Bash command │       │  Input: Commit msg   │
   │  Output: Modified    │       │  Output: Modified    │
   └──────────────────────┘       └──────────────────────┘

For Humans

Quick Start

# Clone terraphim-ai repository
git clone https://github.com/terraphim/terraphim-ai
cd terraphim-ai

# Build the agent
cargo build -p terraphim_agent --release

# Install all hooks (recommended)
./scripts/install-terraphim-hooks.sh --easy-mode

# Test replacement
echo "npm install react" | ./target/release/terraphim-agent replace
# Output: bun install react

Manual Installation

Git Hook (prepare-commit-msg):

cp scripts/hooks/prepare-commit-msg .git/hooks/
chmod +x .git/hooks/prepare-commit-msg

Claude Code Hook (PreToolUse):

Add to .claude/settings.local.json:

{
  "hooks": {
    "PreToolUse": [{
      "matcher": "Bash",
      "hooks": [{
        "type": "command",
        "command": ".claude/hooks/npm_to_bun_guard.sh"
      }]
    }]
  }
}

CLI Usage

# Basic replacement
echo "npm install package" | terraphim-agent replace
# Output: bun install package

# With JSON output (for programmatic use)
echo "npm install" | terraphim-agent replace --json
# Output: {"result":"bun install","original":"npm install","replacements":1,"changed":true}

# Fail-open mode (returns original on error)
echo "npm install" | terraphim-agent replace --fail-open

Adding Custom Replacements

Create markdown files in docs/src/kg/:

# my_term

Description of the replacement term.

synonyms:: term_to_replace, another_term, third_term

Example - Replace pytest with cargo test:

Create docs/src/kg/cargo_test.md:

# cargo test

Rust's built-in test runner using Cargo.

synonyms:: pytest, py.test, python -m pytest

For AI Agents

Detecting Terraphim Capabilities

Check for terraphim-agent availability:

# Check if agent is available
if command -v terraphim-agent >/dev/null 2>&1; then
    echo "Terraphim agent available"
elif [ -x "./target/release/terraphim-agent" ]; then
    AGENT="./target/release/terraphim-agent"
elif [ -x "$HOME/.cargo/bin/terraphim-agent" ]; then
    AGENT="$HOME/.cargo/bin/terraphim-agent"
fi

Using Replacement in Hooks

PreToolUse Hook Pattern:

#!/bin/bash
# Read JSON input
INPUT=$(cat)
TOOL_NAME=$(echo "$INPUT" | jq -r '.tool_name')
COMMAND=$(echo "$INPUT" | jq -r '.tool_input.command')

# Only process Bash commands
[ "$TOOL_NAME" != "Bash" ] && exit 0

# Perform replacement with fail-open
REPLACED=$(terraphim-agent replace --fail-open <<< "$COMMAND")

# Output modified tool_input if changed
if [ "$REPLACED" != "$COMMAND" ]; then
    echo "$INPUT" | jq --arg cmd "$REPLACED" '.tool_input.command = $cmd'
fi

Git Hook Pattern:

#!/bin/bash
COMMIT_MSG_FILE=$1

# Read original message
ORIGINAL=$(cat "$COMMIT_MSG_FILE")

# Replace using knowledge graph
REPLACED=$(terraphim-agent replace --fail-open <<< "$ORIGINAL")

# Write back if changed
if [ "$REPLACED" != "$ORIGINAL" ]; then
    echo "$REPLACED" > "$COMMIT_MSG_FILE"
fi

Programmatic Usage (Rust)

use terraphim_hooks::{ReplacementService, HookResult};
use terraphim_types::Thesaurus;

// Load thesaurus from knowledge graph
let thesaurus = load_thesaurus_from_kg("docs/src/kg/");

// Create replacement service
let service = ReplacementService::new(thesaurus);

// Perform replacement
let result: HookResult = service.replace_fail_open("npm install react");
// result.result == "bun install react"
// result.changed == true
// result.replacements == 1

MCP Tool Integration

The replace_matches MCP tool provides the same functionality:

{
  "tool": "replace_matches",
  "arguments": {
    "text": "npm install react",
    "role": "Default"
  }
}

Hook Types and Use Cases

Error Handling

Hooks use fail-open semantics:

• If terraphim-agent is not found: pass through unchanged
• If replacement fails: return original text
• Errors logged to stderr only in verbose mode

Enable verbose mode:

export TERRAPHIM_VERBOSE=1

Knowledge Graph Format

Knowledge graph files use markdown with frontmatter:

# term_name

Optional description.

synonyms:: synonym1, synonym2, synonym3

Matching behavior:

• Aho-Corasick with LeftmostLongest matching
• Longer patterns match before shorter ones
• Case-sensitive by default

Validation

Test your hooks:

# Run test script
./scripts/test-terraphim-hooks.sh

# Manual test - PreToolUse
echo '{"tool_name":"Bash","tool_input":{"command":"npm install"}}' | .claude/hooks/npm_to_bun_guard.sh

# Manual test - Git hook
echo "Claude Code generated this" | terraphim-agent replace

Troubleshooting

Related Skills

• implementation - For building custom hooks
• testing - For validating hook behavior
• devops - For CI/CD integration with hooks