feat(agent): auto-renew the host cert in the native run-loop (A5)

Wire createCertRotator/renewCert into superviseNative so the frp-client cert
renews silently at ~2/3 TTL over mTLS /renew and frpc restarts onto the fresh
leaf; failures retry with backoff, never crash the supervisor. mTLS transport
has a 15s timeout + 64KB response cap. 281 tests pass.

agent/test/nativeRenewTransport.test.ts

@@ -0,0 +1,168 @@
+/**
+ * A5 default mTLS transport (`defaultMtlsRequest`) — the ONE seam the other nativeRenew tests inject
+ * past, so the real `node:https` transport had zero coverage. These tests mock `node:https` and drive
+ * the actual transport to prove:
+ *   - the exact request options (rejectUnauthorized:true + client cert/key + pinned CA + method/body),
+ *   - the HIGH fix: a request timeout is armed and a stalled peer REJECTS (never hangs forever),
+ *   - the MEDIUM fix: an oversized response body is capped (destroyed + rejected, not buffered).
+ */
+import { EventEmitter } from 'node:events'
+import { mkdtempSync, rmSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const { requestMock } = vi.hoisted(() => ({ requestMock: vi.fn() }))
+vi.mock('node:https', () => ({ request: requestMock, default: { request: requestMock } }))
+
+import { generateP256Identity } from '../src/keys/identity.js'
+import { openKeystore } from '../src/keys/keystore.js'
+import {
+  createMtlsFetch,
+  RENEW_REQUEST_TIMEOUT_MS,
+  MAX_RENEW_RESPONSE_BYTES,
+} from '../src/certs/nativeRenew.js'
+
+const farFuture = (): { validTo: Date } => ({ validTo: new Date(Date.now() + 86_400_000) })
+
+/** Fake `http.ClientRequest`: records setTimeout/write/end and emits 'error' on destroy(err). */
+class FakeClientRequest extends EventEmitter {
+  readonly setTimeoutCalls: Array<{ ms: number; cb: () => void }> = []
+  readonly written: string[] = []
+  ended = false
+  destroyedWith: Error | undefined
+  setTimeout(ms: number, cb: () => void): this {
+    this.setTimeoutCalls.push({ ms, cb })
+    return this
+  }
+  write(chunk: string): boolean {
+    this.written.push(chunk)
+    return true
+  }
+  end(): this {
+    this.ended = true
+    return this
+  }
+  destroy(err?: Error): this {
+    this.destroyedWith = err
+    if (err) this.emit('error', err)
+    return this
+  }
+}
+
+/** Fake `http.IncomingMessage`: an EventEmitter with a statusCode and a real destroy(). */
+class FakeIncomingMessage extends EventEmitter {
+  statusCode = 200
+  destroyed = false
+  destroy(): this {
+    this.destroyed = true
+    return this
+  }
+}
+
+type ReqCb = (res: FakeIncomingMessage) => void
+let dirs: string[] = []
+
+function enrolledKs(): ReturnType<typeof openKeystore> {
+  const dir = mkdtempSync(join(tmpdir(), 'wta-nrt-'))
+  dirs.push(dir)
+  const ks = openKeystore(dir)
+  ks.saveIdentity(generateP256Identity())
+  ks.saveCert('LEAFCERT', 'CACHAIN')
+  return ks
+}
+
+beforeEach(() => {
+  requestMock.mockReset()
+})
+afterEach(() => {
+  for (const d of dirs) rmSync(d, { recursive: true, force: true })
+  dirs = []
+})
+
+describe('defaultMtlsRequest transport (A5 — real node:https)', () => {
+  it('passes rejectUnauthorized:true + the client cert/key/CA + method/body, and arms the timeout', async () => {
+    const ks = enrolledKs()
+    let seenUrl = ''
+    let seenOpts: Record<string, unknown> = {}
+    let seenReq: FakeClientRequest | undefined
+    requestMock.mockImplementation((url: string, opts: Record<string, unknown>, cb: ReqCb) => {
+      seenUrl = url
+      seenOpts = opts
+      const req = new FakeClientRequest()
+      seenReq = req
+      queueMicrotask(() => {
+        const res = new FakeIncomingMessage()
+        res.statusCode = 200
+        cb(res)
+        res.emit('data', Buffer.from('{"cert":"NEW",'))
+        res.emit('data', Buffer.from('"caChain":"NEWCA"}'))
+        res.emit('end')
+      })
+      return req
+    })
+
+    const f = createMtlsFetch(ks, { certParser: farFuture }) // NO request seam → real defaultMtlsRequest
+    const res = await f('https://cp.example.com/renew', {
+      method: 'POST',
+      headers: { 'content-type': 'application/json' },
+      body: '{"csr":"x"}',
+    })
+
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({ cert: 'NEW', caChain: 'NEWCA' })
+    expect(seenUrl).toBe('https://cp.example.com/renew')
+    expect(seenOpts.rejectUnauthorized).toBe(true) // anti-MITM (INV14)
+    expect(seenOpts.method).toBe('POST')
+    expect(seenOpts.cert).toBe('LEAFCERT')
+    expect(seenOpts.ca).toBe('CACHAIN')
+    expect(String(seenOpts.key)).toContain('PRIVATE KEY') // in-process PKCS#8 key
+    // HIGH fix: a socket timeout is armed with the sane default so a stall can never hang forever.
+    expect(seenReq!.setTimeoutCalls).toHaveLength(1)
+    expect(seenReq!.setTimeoutCalls[0]!.ms).toBe(RENEW_REQUEST_TIMEOUT_MS)
+    expect(seenReq!.written).toEqual(['{"csr":"x"}'])
+    expect(seenReq!.ended).toBe(true)
+  })
+
+  it('HIGH: a stalled peer (accepts TLS, never responds) REJECTS via the timeout, not hangs', async () => {
+    const ks = enrolledKs()
+    let seenReq: FakeClientRequest | undefined
+    requestMock.mockImplementation(() => {
+      const req = new FakeClientRequest()
+      seenReq = req
+      return req // never invokes the response callback — a stalled control-plane
+    })
+
+    const f = createMtlsFetch(ks, { certParser: farFuture })
+    const p = f('https://cp.example.com/renew', { method: 'POST', body: '{}' })
+
+    // Fire the armed socket-timeout callback (what node does when the socket idles past the limit).
+    expect(seenReq!.setTimeoutCalls).toHaveLength(1)
+    expect(seenReq!.setTimeoutCalls[0]!.ms).toBe(RENEW_REQUEST_TIMEOUT_MS)
+    seenReq!.setTimeoutCalls[0]!.cb()
+
+    await expect(p).rejects.toThrow(/timed out/i)
+    expect(seenReq!.destroyedWith).toBeInstanceOf(Error) // socket was torn down
+  })
+
+  it('MEDIUM: an oversized response body is capped — res destroyed + promise rejected', async () => {
+    const ks = enrolledKs()
+    let seenRes: FakeIncomingMessage | undefined
+    requestMock.mockImplementation((_url: string, _opts: unknown, cb: ReqCb) => {
+      const req = new FakeClientRequest()
+      queueMicrotask(() => {
+        const res = new FakeIncomingMessage()
+        res.statusCode = 200
+        seenRes = res
+        cb(res)
+        res.emit('data', Buffer.alloc(MAX_RENEW_RESPONSE_BYTES + 1)) // one byte over the cap
+        // deliberately NO 'end' — a capped stream must reject on its own, not wait for end
+      })
+      return req
+    })
+
+    const f = createMtlsFetch(ks, { certParser: farFuture })
+    await expect(f('https://cp.example.com/renew', { method: 'POST' })).rejects.toThrow(/cap|exceed/i)
+    expect(seenRes!.destroyed).toBe(true)
+  })
+})