feat: Android Wi-Fi device pairing (QR + pairing code) with remember/auto-reconnect

[DevSrSouza]

What

Pair physical Android devices over Wi-Fi from Jaca — a sheet launched from the Devices area, driving the adb CLI. Supports both pairing modes plus a remember/auto-reconnect layer that adb itself lacks.

• QR mode — generate a service name + password, render the QR (CoreImage, no deps), and auto-pair the moment the phone advertises _adb-tls-pairing._tcp under our name.
• Pairing-code mode — a live mDNS discovery list plus a manual ip:port field (the phone shows it) so pairing still works on networks that block multicast.
• Better than the silent failures — parses and shows adb's actual error, detects a disabled mDNS daemon via adb mdns check, and offers a one-click adb kill-server recovery.
• Remember + auto-recover — persists paired devices (name, last IP, method, last-seen) under Application Support and reattaches them in the background when their _adb-tls-connect service reappears.

Why

Android Studio's wireless pairing fails silently and doesn't auto-recover or remember devices. This mirrors the official flow (researched against the AOSP adb and Android Studio tools-base/adblib sources) and fills those gaps.

Files

Area	File
mDNS model + pure parser	Core/Devices/MdnsService.swift
adb wrapper + pure result/health parsers	Core/Devices/AdbPairingService.swift
QR payload + credentials (pure)	Core/Devices/QrPairing.swift
Paired-device persistence + reconnect join	Core/Devices/PairedDeviceStore.swift
State machine + discovery loop	Model/PairingModel.swift
Sheet UI (QR + code tabs)	Features/Pairing/PairDeviceSheet.swift
Factory + background reconnect loop	Model/AppModel.swift
Header + empty-state entry points	Features/Sidebar/DeviceSidebarView.swift

Design notes

• Discovery polls the text adb mdns services every ~1s rather than the protobuf host:track-mdns-services stream (that stream is new-adb-2025+ only; polling text is universal, sub-second, and trivially testable). Upgrading to the live stream is a possible follow-up.
• No blind subnet scan — pairing/connect ports are random, ephemeral, and only open briefly, so scanning is low-value and can trip network security. The manual ip:port fallback + targeted remembered-host reconnect cover the mDNS-blocked case instead.

Test plan

• ✅ Tests/PairingTests.swift — 17 cases over the pure logic (mDNS parser, PairResult, MdnsHealth, QR payload/credentials, paired-device store + reconnect join). All green.
• ✅ Release build installs and launches; sheet opens full-size with the QR pre-rendered and an ✕ close button.
• ⚠️ Not yet exercised end-to-end against a physical device — the live SPAKE2 pair handshake needs a real Android phone to confirm. Draft until that's verified.

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