PR #15840 — Connections endpoint refresh
Base: 1451e7cb23034d29774338608368a15d8845df36
Head: 6ae853de355048cf67a2cfa36e181de4b91f1bd3

Focused suites: exact-main production 1 failed / 20 passed; takeover 21 passed.
Desktop typecheck, targeted lint and format check passed.

Headless integration: production DesktopServerExposure service with real Node child processes,
controlled tailscale status executable, isolated temporary T3 home and simulated OS interface snapshots.
No host network changes. Synthetic endpoint names and addresses only.

BEFORE (exact main production, same fixture):
Cached empty status remains cached when vpn0 appears.
Actual endpoint URLs: http://127.0.0.1:4173/, http://192.168.1.20:4173/.
Expected newly connected IP and MagicDNS are absent. CLI read count remains 1.
Assertion for http://100.90.1.2:4173/ fails.

AFTER:
{"phase":"connected","urls":["http://127.0.0.1:4173/","http://192.168.1.20:4173/","http://100.90.1.2:4173/","https://desktop.tail.ts.net/"],"cliReads":2}
{"phase":"changed","urls":["http://127.0.0.1:4173/","http://192.168.1.20:4173/","http://100.90.1.3:4173/","https://desktop.other-tail.ts.net/"],"cliReads":3}
{
  "result": "PASS",
  "execution": "production desktop service, real child processes, controlled CLI and interface snapshots",
  "observations": [
    {
      "phase": "disconnected",
      "urls": [
        "http://127.0.0.1:4173/",
        "http://192.168.1.20:4173/"
      ],
      "cliReads": 1
    },
    {
      "phase": "connected",
      "urls": [
        "http://127.0.0.1:4173/",
        "http://192.168.1.20:4173/",
        "http://100.90.1.2:4173/",
        "https://desktop.tail.ts.net/"
      ],
      "cliReads": 2
    },
    {
      "phase": "connected cached",
      "urls": [
        "http://127.0.0.1:4173/",
        "http://192.168.1.20:4173/",
        "http://100.90.1.2:4173/",
        "https://desktop.tail.ts.net/"
      ],
      "cliReads": 2
    },
    {
      "phase": "changed",
      "urls": [
        "http://127.0.0.1:4173/",
        "http://192.168.1.20:4173/",
        "http://100.90.1.3:4173/",
        "https://desktop.other-tail.ts.net/"
      ],
      "cliReads": 3
    },
    {
      "phase": "changed cached",
      "urls": [
        "http://127.0.0.1:4173/",
        "http://192.168.1.20:4173/",
        "http://100.90.1.3:4173/",
        "https://desktop.other-tail.ts.net/"
      ],
      "cliReads": 3
    }
  ]
}

Limits: no live Electron window, physical network switch, real Tailscale daemon,
macOS TCC, Windows, mobile clients or authenticated pairing exercised.
The renderer fix and its six focused tests already exist on current main.