feat(relay): rendezvous-relay service — 7 packages + plans (contracts/transport/agent/control-plane/e2e/auth/web)

Multi-tenant reverse-tunnel service ("ngrok for Claude Code" with E2E): a
host-agent dials OUT to an operator-run relay; external devices reach the host
THROUGH the relay, routed by per-tenant subdomain, forwarding ciphertext only
(the relay never sees plaintext). Lets a customer reach their own self-hosted
web-terminal from anywhere with zero networking setup.

Packages — all tsc-strict + vitest green (656 tests), cross-package integration verified:
- relay-contracts: frozen shared contracts (mux frame codec, data model,
  capability token, E2E envelope, pairing) — the src/types.ts analog
- term-relay:   native WS mux + stateless data plane (subdomain routing, ciphertext forward)
- agent:        host-agent (pairing, per-host Ed25519 + mTLS dial-out, forwards to 127.0.0.1:3000)
- control-plane: accounts/hosts registry, pairing-code flow, routing table, provisioning
- relay-e2e:    browser<->agent E2E (X25519 ECDH through relay, AEAD, anti-replay, recoverable replay key)
- relay-auth:   Passkey/WebAuthn, capability tokens, per-host certs, deny-by-default tenant isolation
- relay-web:    browser login + Web Crypto E2E + client-side preview rendering

Security invariants INV1-15 enforced; cross-tenant isolation CI tripwire live
(.github/workflows/relay-tripwire.yml). Design + implementation-level plans in
docs/PLAN_RELAY_*.md and docs/EXPLORE_RELAY_SERVICE.md.

NOTE: generated autonomously per the reviewed plans. The security-critical
packages (relay-e2e, relay-auth) REQUIRE expert security audit before any real
deployment — passing tests prove self-consistency, not resistance to attackers.
Base app (src/, public/) unchanged; concurrent desktop work left uncommitted.

agent/test/pair.test.ts

@@ -0,0 +1,105 @@
+import { describe, expect, it, vi } from 'vitest'
+import { mkdtempSync, rmSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { encodeBase64UrlBytes } from 'relay-contracts'
+import { generateIdentity } from '../src/keys/identity.js'
+import { openKeystore } from '../src/keys/keystore.js'
+import {
+  DEFAULT_ENROLL_MODE,
+  EnrollError,
+  PairingCodeExpiredError,
+  PairingCodeSpentError,
+  redeemPairingCode,
+} from '../src/enroll/pair.js'
+
+const ENROLL_URL = 'https://example.com/enroll'
+const VALID_UUID = '11111111-1111-4111-8111-111111111111'
+
+function freshKs() {
+  const dir = mkdtempSync(join(tmpdir(), 'wta-pair-'))
+  return { dir, ks: openKeystore(dir) }
+}
+
+function jsonResponse(status: number, body: unknown): Response {
+  return {
+    ok: status >= 200 && status < 300,
+    status,
+    json: async () => body,
+  } as unknown as Response
+}
+
+function okBody(wrappedSecret: Uint8Array) {
+  return {
+    hostId: VALID_UUID,
+    subdomain: 'host-42',
+    cert: 'CERTPEM',
+    caChain: 'CAPEM',
+    hostContentSecret: encodeBase64UrlBytes(wrappedSecret),
+  }
+}
+
+describe('redeemPairingCode (§4.5, T4)', () => {
+  it('defaults to ed25519 mode', () => {
+    expect(DEFAULT_ENROLL_MODE).toBe('ed25519')
+  })
+
+  it('sends only pubkey + csr, never the private key (INV4)', async () => {
+    const { dir, ks } = freshKs()
+    const id = generateIdentity()
+    const fetchImpl = vi.fn(async (_u: string | URL | Request, init?: RequestInit) => {
+      const body = JSON.parse(String(init!.body)) as Record<string, unknown>
+      expect(body).toHaveProperty('agentPubkey')
+      expect(body).toHaveProperty('csr')
+      expect(JSON.stringify(body)).not.toContain('PRIVATE KEY')
+      expect(body).not.toHaveProperty('privateKey')
+      return jsonResponse(200, okBody(new Uint8Array([9, 9, 9])))
+    })
+    await redeemPairingCode(ENROLL_URL, 'ABCD-1234', id, ks, { fetchImpl: fetchImpl as unknown as typeof fetch })
+    rmSync(dir, { recursive: true, force: true })
+  })
+
+  it('stores cert + unwrapped content secret; wrapped bytes not persisted (FIX 3)', async () => {
+    const { dir, ks } = freshKs()
+    const id = generateIdentity()
+    const wrapped = new Uint8Array([1, 2, 3])
+    const unwrapped = new Uint8Array([7, 7, 7])
+    const fetchImpl = async () => jsonResponse(200, okBody(wrapped))
+    await redeemPairingCode(ENROLL_URL, 'ABCD-1234', id, ks, {
+      fetchImpl: fetchImpl as unknown as typeof fetch,
+      unwrapContentSecret: () => unwrapped,
+    })
+    expect(ks.loadCert()).toEqual({ certPem: 'CERTPEM', caChainPem: 'CAPEM' })
+    const stored = ks.loadContentSecret()!
+    expect(Buffer.from(stored).equals(Buffer.from(unwrapped))).toBe(true)
+    expect(Buffer.from(stored).equals(Buffer.from(wrapped))).toBe(false)
+    rmSync(dir, { recursive: true, force: true })
+  })
+
+  it('maps 409 → PairingCodeSpentError (single-use)', async () => {
+    const { dir, ks } = freshKs()
+    const fetchImpl = async () => jsonResponse(409, {})
+    await expect(
+      redeemPairingCode(ENROLL_URL, 'X', generateIdentity(), ks, { fetchImpl: fetchImpl as unknown as typeof fetch }),
+    ).rejects.toBeInstanceOf(PairingCodeSpentError)
+    rmSync(dir, { recursive: true, force: true })
+  })
+
+  it('maps 410 → PairingCodeExpiredError', async () => {
+    const { dir, ks } = freshKs()
+    const fetchImpl = async () => jsonResponse(410, {})
+    await expect(
+      redeemPairingCode(ENROLL_URL, 'X', generateIdentity(), ks, { fetchImpl: fetchImpl as unknown as typeof fetch }),
+    ).rejects.toBeInstanceOf(PairingCodeExpiredError)
+    rmSync(dir, { recursive: true, force: true })
+  })
+
+  it('rejects a schema-mismatched response (boundary validation)', async () => {
+    const { dir, ks } = freshKs()
+    const fetchImpl = async () => jsonResponse(200, { hostId: 'not-a-uuid', subdomain: 'x' })
+    await expect(
+      redeemPairingCode(ENROLL_URL, 'X', generateIdentity(), ks, { fetchImpl: fetchImpl as unknown as typeof fetch }),
+    ).rejects.toBeInstanceOf(EnrollError)
+    rmSync(dir, { recursive: true, force: true })
+  })
+})