Other Languages

Other languages: TypeScript, Go, Java, anything

Native bindings exist for Rust, Python and Node.js. Everyone else has two routes today, both complete, and a third on the Roadmap.

TypeScript / Node.js

Three npm packages; the TypeScript quickstart walks through them.

• @witness-log/node (clients/node): the Rust core as a prebuilt napi-rs addon. openLog, appendIntent/appendResult/appendMemory, step, forget, disclose, exportDossier, submit to witnesses over fetch, verifyDossier (pure TypeScript) and verifyDossierNative (the Rust verifier). No Rust toolchain, no Python, no CLI.
• @witness-log/ai-sdk (clients/ai-sdk): Vercel AI SDK v5. witnessTools(tools, log), witnessMiddleware(log), witnessTelemetry(log).
• @witness-log/client (clients/typescript): the pure-TypeScript verifier on its own, plus typed wrappers for the witness-log CLI (WitnessLogCLI) and the MCP server (WitnessLogMCP).

import { openLog, verifyDossier } from "@witness-log/node";

const log = openLog("agent.jsonl");
const refund = await log.step("stripe.refund", () => stripe.refund(1042), { args: { order: 1042 } });
const dossier = log.exportDossier();
const v = verifyDossier(dossier, { identity: log.identityPubkey, directory: trusted, minWitnesses: 2 });
if (!v.ok) throw new Error(v.verdict);   // ok: WITNESSED with exit 0; v.exitCode is 0/11/10/20/30/40

npm create witness-log my-agent generates a working project (plain or --template ai-sdk).

Route 1: MCP (any language with an MCP client)

Any MCP client library can drive the server (witness-log-mcp, or python -m witness_log.mcp_server, from pip install "witness-log[mcp]") over stdio. Its eleven tools cover logging, proofs, redaction, export, witnessing and verification; your code never touches the format.

TypeScript with the SDK directly (Vercel AI SDK / LangChain.js / Mastra / custom):

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";

const transport = new StdioClientTransport({
  command: "uvx",
  args: ["--from", "witness-log[mcp]", "witness-log-mcp"],
  env: { ...process.env, WITNESS_LOG_HOME: "/var/lib/witness-log" },
});
const wl = new Client({ name: "my-agent", version: "1.0.0" });
await wl.connect(transport);
await wl.callTool({ name: "initialize_witness_chain", arguments: { session_id: "orders-bot" } });

// before the tool call: the intent
const i = await wl.callTool({ name: "append_audit_step", arguments: {
  session_id: "orders-bot", intent: "refund order 1042", tool_name: "stripe.refund",
  payload: { order: 1042, amount: 250 } } });
// after it: the result, bound to the intent's index
await wl.callTool({ name: "record_result", arguments: {
  session_id: "orders-bot", intent_index: i.structuredContent.result.intent_index,
  tool_name: "stripe.refund", value: { refunded: true } } });

Vercel AI SDK users can also expose the server's tools directly to the model with experimental_createMCPClient and instruct it to record steps.

Route 2: the CLI (any language, no Python)

Write the dossier yourself and verify with the binary. The dossier is plain JSON (spec/dossier.schema.json); the leaf encoding and hashes are specified in spec/SPEC.md with test vectors in corpus/. For verification only you need nothing but the binary:

cmd := exec.Command("witness-log", "verify", "dossier.json",
    "--identity", key, "--directory", "trusted.json", "--min-witnesses", "2", "--json")
out, _ := cmd.Output()   // err is non-nil for any non-zero exit; the exit code is the verdict
switch cmd.ProcessState.ExitCode() {
case 0: /* WITNESSED by a majority of your directory */
case 11, 10, 20: /* not enough: sub-majority, unwitnessed, unanchored */
case 30, 40: /* refuse: contradicts a head or proof you supplied (30), a check failed (40) */
default: /* 2: usage */ }

Producing dossiers from another language means implementing §2–§6 of the spec (SHA-256, Ed25519, length-prefixed fields). witness-log conform <your-corpus-dir> --reference <checkout>/corpus tells you the moment you match byte for byte (--reference defaults to ./corpus, so it can be omitted when run from a checkout). The reference generator is crates/witness-log-core/examples/generate_corpus.rs.

Route 3 (roadmap): native packages

@witness-log/core (napi-rs, same Rust core) and a Go module are the next bindings; the C ABI they share is tracked in the roadmap. If you need one, say so in Discussions: demand decides order.