lgtv/DECISIONS.md

LG TV Bridge — Decisions

Format: YYYY-MM-DD: <decision> — <why>

• 2026-06-01: Single bridge, single host — runs on steel141, pve173 retired. The bridge had been running on pve173 (always-on node) since 2026-03-23, SSHing to steel141 for every TV op. Consolidated everything onto steel141. Why: the WebOS pairing key (/home/seth/.aiopylgtv.sqlite) lives only on steel141, so power_off always routes through it regardless of bridge host — pve173 added an SSH hop and a second host for no real availability gain (the TV is uncontrollable whenever steel141 is down anyway). One host, no SSH hop.

• 2026-06-01: Cached-IP discovery, sweep only on miss. Persist last-known TV IP in ~/.cache/lgtv/last_ip; probe it directly (TCP :3000/:3001). Full /24 ping-sweep runs only on a cache miss, then re-caches. Why: the old code ping-swept all 254 hosts over SSH on every 30s HA state poll — slow, network spam, and racy (stale ARP) → the chronic "flaky state in HA" symptom.

• 2026-06-01: Robust WoL — unicast + broadcast, ports 9/7, 3 bursts. Why: old code sent broadcast-only on ports 9/1235 once. Unreliable wakes. NOTE: the remaining wake failures are TV-side (Quick Start+ / Mobile TV On must be ON; wired Ethernet far more reliable than Wi-Fi for LG WoL) — not fixable in code.

• 2026-06-01: Deps via pip --user --break-system-packages for seth. paho

  • bscpylgtv live in /home/seth/.local (PEP 668 box). Matches how bscpylgtv was already installed; the systemd unit runs User=seth.

• 2026-06-01: power_off must pass an absolute key_file_path. bscpylgtv's StorageSqliteDict defaults the key DB to os.getcwd()/.aiopylgtv.sqlite (its $USER_HOME fallback is not $HOME). The old pve173 setup worked only because it SSHed in as seth, landing CWD in /home/seth. Under systemd (cwd=/) it threw sqlite3.OperationalError: unable to open database file. Fix: WebOsClient.create(ip, key_file_path="~/.aiopylgtv.sqlite").

• 2026-06-01: power_off retries (2×, 10s apart). A TV woken seconds earlier answers TCP :3000 but refuses a WebSocket control session for ~20-30s, so an immediate OFF-after-ON can fail. Retry covers it; normal case (TV already up) succeeds first try in ~3s. Bounded under the bridge's 60s subprocess timeout.

Deferred / Rejected

• DHCP reservation for the TV (static IP): not done — Pi-hole doesn't run DHCP (router does), so it's Seth's action on the router. The cached-IP probe makes it unnecessary for correctness; a reservation would just let us drop the sweep-fallback entirely. Add if convenient.
• Unique per-instance MQTT client_id: rejected — keeping a fixed lgtv-bridge id means a duplicate instance is loud (reconnect war in broker logs) rather than silent. Single-instance discipline is the real guard. (A duplicate on 2026-06-01 during this very migration is what surfaced all this.)