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.

relay-auth/test/stepup.test.ts

@@ -0,0 +1,46 @@
+import { describe, it, expect } from 'vitest'
+import { needsStepUp, recordStepUp, policyForHost } from '../src/human/stepup/stepup.js'
+import type { StepUpPolicy } from '../src/types.js'
+import { principal, makeHost, uuid } from './_helpers.js'
+
+const NOW = 1_700_000_000
+const POLICY: StepUpPolicy = { maxAgeSeconds: 300, requiredMethod: 'passkey' }
+
+describe('step-up before session open (T8, Finding-3)', () => {
+  it('fresh login but stepUpAt=null → needsStepUp true (login ≠ step-up)', () => {
+    const p = principal('acct-A', { authAt: NOW, stepUpAt: null, amr: ['passkey'] })
+    expect(needsStepUp(p, POLICY, NOW)).toBe(true)
+  })
+
+  it('stale step-up (older than maxAgeSeconds) → true', () => {
+    const p = principal('acct-A', { stepUpAt: NOW - 301, amr: ['passkey', 'stepup'] })
+    expect(needsStepUp(p, POLICY, NOW)).toBe(true)
+  })
+
+  it('required method absent from amr → true', () => {
+    const p = principal('acct-A', { stepUpAt: NOW, amr: ['totp'] })
+    expect(needsStepUp(p, POLICY, NOW)).toBe(true)
+  })
+
+  it('fresh passkey step-up → false', () => {
+    const p = principal('acct-A', { stepUpAt: NOW, amr: ['passkey'] })
+    expect(needsStepUp(p, POLICY, NOW)).toBe(false)
+  })
+
+  it('recordStepUp returns a NEW principal (immutable), original untouched', () => {
+    const p = principal('acct-A', { stepUpAt: null, amr: ['totp'] })
+    const stepped = recordStepUp(p, 'passkey', NOW)
+    expect(stepped).not.toBe(p)
+    expect(p.stepUpAt).toBeNull()
+    expect(p.amr).toEqual(['totp'])
+    expect(stepped.stepUpAt).toBe(NOW)
+    expect(stepped.amr).toContain('passkey')
+    expect(needsStepUp(stepped, POLICY, NOW)).toBe(false)
+  })
+
+  it('policyForHost yields a passkey freshness requirement', () => {
+    const policy = policyForHost(makeHost('acct-A', uuid()))
+    expect(policy.requiredMethod).toBe('passkey')
+    expect(policy.maxAgeSeconds).toBeGreaterThan(0)
+  })
+})