@fidacy/session

Conversation receipts for AI chatbots.

Your support bot talks to customers about claims, prescriptions, refunds, contracts. When a dispute comes, the question is always the same: what exactly was said, and can either side prove the transcript wasn't edited after the fact? A court already answered what happens without proof (Air Canada, 2024: the airline was held to what its chatbot said).

This SDK gives every session a tamper-evident digest, computed locally, message by message. At session close you anchor the digest through Fidacy, where it joins an audit chain checkpointed to the Bitcoin blockchain, and you get a signed receipt. Hand the verify link to the customer too: proof both sides can hold is the only proof that settles arguments.

The transcript never leaves your infrastructure. Only a 64-hex SHA-256 travels. That is the whole privacy story, and it is why this works for hospitals and insurers.

Install

npm i @fidacy/session

Use

import { createSession } from "@fidacy/session";

const session = createSession({ kind: "conversation", label: "case-4711" });

// wire into your chat loop
session.add("user", "I want to file a claim for water damage.");
session.add("assistant", "I can help. When did it happen?");
session.add("user", "Last Tuesday.");

// at session close: anchor the digest (content never leaves your machine)
const receipt = await session.anchor({ apiKey: process.env.FIDACY_ENGINE_API_KEY! });

// store the transcript + receipt; give the customer the public verify link
const transcript = session.export();
console.log(session.verifyUrl()); // https://fidacy.com/verify?sha256=…

Verify, without trusting anyone

The digest recipe is public. Anyone holding the exported transcript recomputes it offline:

import { digestTranscript } from "@fidacy/session";
digestTranscript(transcript.messages) === transcript.sha256; // true, or it was tampered

• h_0 = sha256("fidacy.session.v1")
• leaf_i = sha256(canonicalJson({ i, role, content, ts }))
• h_i = sha256(h_{i-1} + "|" + leaf_i)

The final head is what gets anchored. Check any digest at fidacy.com/verify (no account), or via the public API: GET https://api.fidacy.com/v1/verify/artifact?sha256=<hex>. The signed receipt verifies against the engine JWKS at https://api.fidacy.com/.well-known/jwks.json.

Changing one character of one message, reordering two messages, or dropping a message produces a different digest. That mismatch is the tampering signal.

What this is not

Fidacy never sees, stores or judges the conversation content. This is integrity and existence proof, not content moderation. To gate what your bot may commit to (refunds, quotes, payouts), pair it with the Fidacy firewall: promises without a signed grant don't bind.

Apache-2.0.