Add Covenant Compute to LangChain.

curl --fail --location --output covenant-compute-x402-client-0.2.0.tgz \
  https://github.com/open-covenant/covenant/releases/download/codex-compute-x402-client-v0.2.0/covenant-compute-x402-client-0.2.0.tgz &&
echo "77ef86146f982432f75a83d227afb8c7a8f36049bb23d4eba29ae0da0cb606cf  covenant-compute-x402-client-0.2.0.tgz" | shasum -a 256 -c - &&
npm install --ignore-scripts ./covenant-compute-x402-client-0.2.0.tgz

import { readFile } from 'node:fs/promises';
import { covenantInferenceTool }
  from '@covenant/compute-x402-client/langchain';

// Your application saves both IDs before the first run.
// Load the same file after a restart; never generate a new ID to retry.
const { requestId, threadId } = JSON.parse(
  await readFile('./state/run.json', 'utf8'),
);

const compute = covenantInferenceTool({
  client, // Configured CovenantX402Client: wallet, journal and spending limits.
  requestId, // One saved UUID for this logical purchase.
  model: 'claude-haiku-4.5',
  maxTokens: 2048,
  temperature: 0.2,
  systemPrompt: 'Draft only. Do not claim account actions or promise refunds.',
});

// The model can supply only { prompt: string }.
// Wallet, model, price limits and request identity stay in application code.

import { createAgent } from 'langchain';

// Use your existing planner and a persistent graph checkpointer.
const agent = createAgent({
  model: planner,
  tools: [compute],
  checkpointer,
});

const result = await agent.invoke({ messages: [{
  role: 'user',
  content: 'Sample ticket: my plan change shows two charges and I cannot '
    + 'download the invoice. Triage it and draft a reply for review.',
}] }, { configurable: { thread_id: threadId } });

const purchase = result.messages
  .findLast(message => message.name === 'covenant_inference')?.artifact;
if (purchase?.status === 'completed') {
  console.log(purchase.text); // Full signed evidence is retained in purchase.
}