---

name: hook-sdk-integration description: LLM invocation patterns from hooks via SDK. Use when you need background agents, CLI calls, or cost optimization. allowed-tools: ["Read", "Grep", "Glob"]

Hook SDK Integration

Patterns for invoking LLM calls from hooks using u-llm-sdk/claude-only-sdk.

IMPORTANT: SDK Detailed Guide

Load when implementing SDK:

Skill("forge-editor:llm-sdk-guide")

This skill covers SDK call pattern interfaces. llm-sdk-guide covers SDK detailed APIs and types.

Quick Start

# Background agent pattern (non-blocking)
(python3 sdk-agent.py "$INPUT" &)
echo '{"status": "started"}'
exit 0

Key Findings (Verified: 2025-12-30)

Item	Result
SDK calls	Possible from hooks
Latency	~30s (CLI session initialization)
Background	Non-blocking execution possible (0.01s return)
Cost	Included in subscription (no additional API cost)

Architecture

Hook (bash) → Background (&) → SDK (Python) → CLI → Subscription usage
     │                                                    │
     └─── Immediate return (0.01s) ───────────────────────┘

Pattern Selection

Situation	Pattern	Reason
Need fast evaluation	type: "prompt"	In-session execution, fast
Need isolation	Direct CLI call	Separate MCP config possible
Complex logic	SDK + Background	Type-safe, non-blocking
Cost reduction	Local LLM (ollama)	Free, privacy

SDK Configuration (Python)

from u_llm_sdk import LLM, LLMConfig
from llm_types import Provider, ModelTier, AutoApproval

config = LLMConfig(
    provider=Provider.CLAUDE,
    tier=ModelTier.LOW,
    auto_approval=AutoApproval.FULL,
    timeout=60.0,
)

async with LLM(config) as llm:
    result = await llm.run("Your prompt")

Cost Structure

Method	Cost
type: "prompt"	Included in subscription
Claude CLI	Included in subscription
SDK via CLI	Included in subscription
Direct API	Per-token billing

References

• LLM SDK Detailed Guide - SDK API details
• SDK Integration Patterns
• Background Agent Implementation
• Cost Optimization
• Real-World Projects