provable-think

Drop-in cryptographic audit trail for Cloudflare Project Think agents.

Every lifecycle hook becomes a tamper-evident, hash-chained receipt anchored to a public cryptographic timestamp ledger no operator controls. The plaintext stays encrypted off-ledger under per-event keys. Auditors with the right viewing key get the cleartext. Wrong key gets AEAD silence.

Why

Logs you control are not audit trails. They are testimony. An audit trail is a record an outside party can verify without trusting the operator. provable-think puts the integrity anchor outside the operator's reach, so the answer to "did the operator change the log?" stops requiring trust.

Install

npm install provable-think

Use

import { Think } from "@cloudflare/think";
import { withProvenance, HIPAA_PRESET } from "provable-think";

export class TriageAgent extends withProvenance(Think<Env>, {
  ...HIPAA_PRESET,
  identity: { envBinding: "AGENT_PRIVATE_KEY_HEX" },
  storage:  { primary: "r2", r2: { binding: "PHI_ENVELOPES" } },
  anchor:   { network: "mainnet" },
}) {}

Every turn, every tool call, every model invocation, every chat response, every recovered fiber fires a cryptographically signed receipt to the public ledger in 10 to 30 seconds.

Live demo

acme-health.pages.dev — a three-pane theater showing receipts landing in real time, a persona-toggled selective-disclosure surface, an 11-step verifier, and a tamper button that flips the verifier red on AEAD failure.

Verifier CLI

npx provable-think-verify --txid <id> --capability <key.json>

11 steps. Signed report. Seconds. See provable-think-verify for the full pipeline.

Cost

Less than a thousandth of a cent per audited decision. Encrypted envelope storage on Cloudflare R2 at standard rates. License: $0 — MIT, free forever.

Status

0.1.0-alpha.0 — the surface documented above ships today. Ongoing roadmap items (additional lifecycle hook coverage, two-Worker key separation, build provenance) are tracked in the GitHub repo.

License

MIT. Copyright (c) 2026 John Calhoun.