# Indie AI-agent dev Quickstart

> For the solo founder shipping a LangChain RAG agent fast. Skip the boilerplate, get a hash-chained audit trail and a signed VC on every chain completion.

## You're here because...

You're a solo or small-team dev shipping a LangChain agent and you don't have time to hand-roll an audit trail before launch. Use the runnable example and the source limitations below to assess whether this workflow meets your requirements.

## 60-second install

```bash
pip install --pre 'attestix[langchain]'
```

That installs v0.4.0-rc.5 plus the `langchain-core` extra. Drop the `--pre` once v0.4.0 GA ships.

## First 30 lines that actually do something

```python
from langchain.agents import AgentExecutor, create_react_agent
from langchain_core.prompts import PromptTemplate
from langchain_openai import ChatOpenAI
from attestix.integrations.langchain import AttestixCallback
from attestix.services.identity_service import IdentityService

# 1. One-time: create the agent identity (signed, persisted to identities.json).
agent = IdentityService().create_identity(
    display_name="rag-helper",
    source_protocol="manual",
    capabilities=["retrieval", "synthesis"],
    issuer_name="VibeTensor",
    expiry_days=365,
)

# 2. Wire the callback. Every tool call, LLM call, and chain step gets
#    SHA-256 hash-chained, Ed25519-signed, and stored locally.
callback = AttestixCallback(
    agent_id=agent["agent_id"],
    record_llm_tokens=True,
    issue_vc_on_success=True,  # default True
)

llm = ChatOpenAI(model="gpt-4o-mini")
prompt = PromptTemplate.from_template("{input}\n{agent_scratchpad}")
executor = AgentExecutor(
    agent=create_react_agent(llm, tools=[], prompt=prompt),
    tools=[],
    callbacks=[callback],
)

result = executor.invoke({"input": "Summarise our Q4 board pack."})
print(result["output"])
```

## What you just got

- A row in the local hash-chained audit trail for every callback event (`on_chain_start`, `on_tool_start`, `on_llm_end`, `on_chain_end`).
- A signed `ChainExecutionCredential` (W3C VC, `Ed25519Signature2020`) auto-issued on chain completion. Verify it offline with `attestix credential --verify <cred_id>`.
- A persistent agent DID so the same identity is reused across runs (no per-run re-creation).

Verify the chain hashes still line up:

```bash
attestix audit <agent_id>
```

The deeper [LangChain integration guide](/docs/guides/langchain) covers chain-of-thought events, sub-chain UCAN delegations, and the full callback event table.

## Next step (5 minutes)

Anchor today's audit batch to **Base L2 testnet** (Sepolia, free, requires a funded test wallet, no mainnet wallet needed):

```python
from attestix.services.blockchain_service import BlockchainService

tx = BlockchainService().anchor_audit_batch(agent_id=agent["agent_id"])
print(tx)  # 0x...; verify on https://sepolia.basescan.org
```

Mainnet schema registration is on the [roadmap](/docs/project/roadmap); until then anchoring is testnet only and is **not** legally non-repudiable. See the [Base L2 anchor walkthrough](/docs/guides/base-l2-anchor) for the full setup.