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-e2e/test/keystore.test.ts

@@ -0,0 +1,67 @@
+import { describe, expect, it } from 'vitest'
+import type { AuthorizedDeviceContext } from 'relay-contracts'
+import { unwrapAeadKey } from '../src/aead-key.js'
+import { deriveContentKey } from '../src/replay-key.js'
+import { buildClientHandshake, MemoryDevicePinStore } from '../src/keystore.js'
+import { createHostHandshake } from '../src/handshake.js'
+import { nobleEd25519Signer } from '../src/ed25519.js'
+import { boundProofProvider, makeHostIdentity, verifyBoundProof, bytesToHex } from './helpers.js'
+import * as publicSurface from '../src/index.js'
+
+function ctxFor(hostContentSecret: Uint8Array): AuthorizedDeviceContext {
+  return {
+    deviceAuthProofProvider: boundProofProvider(),
+    pinStore: new MemoryDevicePinStore(),
+    hostContentSecret,
+  }
+}
+
+describe('T11 multi-device adapters (authenticated channel, NOT a QR)', () => {
+  it('two authorized contexts (same secret) each complete a handshake + derive matching K_content', async () => {
+    const id = makeHostIdentity()
+    const secret = new Uint8Array(32).fill(0x55)
+    const mkHost = () =>
+      createHostHandshake({
+        signer: nobleEd25519Signer(id.privateKey),
+        agentPubkey: id.agentPubkey,
+        supported: ['xchacha20-poly1305', 'aes-256-gcm'],
+        verifyDeviceProof: async (p, b) => verifyBoundProof(p, b),
+      })
+
+    for (const label of ['deviceA', 'deviceB']) {
+      const ch = buildClientHandshake(ctxFor(secret), 'h1', ['xchacha20-poly1305'])
+      const host = mkHost()
+      const hello = await ch.start()
+      const hostHello = await host.onClientHello(hello)
+      const result = await ch.onHostHello(hostHello, id.agentPubkey)
+      expect(result.aead).toBe('xchacha20-poly1305')
+      expect(label).toBeTruthy()
+    }
+    const kA = deriveContentKey({ hostContentSecret: secret, sessionId: 's', alg: 'aes-256-gcm' })
+    const kB = deriveContentKey({ hostContentSecret: secret, sessionId: 's', alg: 'aes-256-gcm' })
+    expect(bytesToHex(unwrapAeadKey(kA).raw)).toBe(bytesToHex(unwrapAeadKey(kB).raw))
+  })
+
+  it('no-QR assertion: the public surface exposes NO key→string/QR serializer', () => {
+    const names = Object.keys(publicSurface)
+    const forbidden = names.filter((n) => /qr|serializekey|exportkey|keytostring|tosharestring/i.test(n))
+    expect(forbidden).toEqual([])
+  })
+
+  it('INV3: a context whose proof is unbound is rejected by the host gate (no session)', async () => {
+    const id = makeHostIdentity()
+    const ctx: AuthorizedDeviceContext = {
+      deviceAuthProofProvider: { async proofFor() { return 'static-bearer-token' } },
+      pinStore: new MemoryDevicePinStore(),
+      hostContentSecret: new Uint8Array(32),
+    }
+    const ch = buildClientHandshake(ctx, 'h1', ['aes-256-gcm'])
+    const host = createHostHandshake({
+      signer: nobleEd25519Signer(id.privateKey),
+      agentPubkey: id.agentPubkey,
+      supported: ['aes-256-gcm'],
+      verifyDeviceProof: async (p, b) => verifyBoundProof(p, b),
+    })
+    await expect(host.onClientHello(await ch.start())).rejects.toBeTruthy()
+  })
+})