[bbangert]

Stacked on #320. Retarget this PR to main before #320 is merged with --delete-branch. Otherwise deleting the base branch closes this PR.

Summary

UI half of #229. Each output card on the Audio tab gets a "Pair through Home Assistant" toggle, in the same style as the CEC toggle rows. It selects the one output whose Sendspin client is reported to Home Assistant (backend in #320).

• Turning it on for an output selects that output and replaces any other selection. Turning it on the selected output off clears the selection.
• The toggle reflects {:home_assistant_pairing, key} broadcasts on HomeAssistantPairing.topic/0, so every open page shows the same selection. The selection is read at mount, so a persisted one shows after a reload.
• While an output is selected, its row shows a short hint: HA hands the token to MA, only over encrypted API connections, one output at a time.
• A failed change (output gone, audio subsystem down, DETS error) flashes "Home Assistant pairing change failed".
• Inputs get no toggle: they still offer only old-wire dynamic_pin.
• The token never goes into the DOM through this feature: the toggle only selects. The existing Show/Copy disclosure is unchanged.

Design decisions

• The toggle is offered on every output card. Every shown output runs a Sendspin player, and a disabled output can still be selected, in which case HA gets DISABLED until the output is turned on.
• The handler doesn't update the assign itself. It waits for the broadcast, so the state on the page is always the state on the server.
• The calls go through the existing :audio_facade test seam (Audio.home_assistant_pairing/0, select_home_assistant_pairing/1, clear_home_assistant_pairing/0).

Testing

• New LiveView tests: off by default on every card, persisted selection at mount, select, move to another output, clear, broadcast-driven state, error flash, and stale or invalid ids ignored.
• mise run test: 3815 passed (8 doctests, 3807 tests), 3 excluded
• Argus: 0 new findings
• mix dialyzer (host, dev): passed
• mix format --check-formatted: clean

HW validation still required on the rpi3 against HA 2026.11 + MA 2.11 dev (the issue's "Done when" boxes):

• HA pairs a selected output with MA end to end
• Changing the selection makes HA see the new client_id after it reconnects

Refs #229

🤖 Generated with Claude Code

[Copilot]

🔵 Needs a closer look

Required rpi3 validation with HA 2026.11 and MA 2.11 dev remains outstanding for end-to-end pairing and client_id updates after switching outputs and reconnecting HA.

No open issues 🎉

What changed in this PR

Adds the Audio-tab UI for #229, building on #320’s backend so users can choose one output for Home Assistant pairing with Music Assistant.

Changes:

• Adds a pairing toggle to every output card without exposing the token through the toggle.
• Loads the persisted selection at mount, follows broadcast updates, and displays failures.
• Adds LiveView tests for selection, switching, clearing, persistence, broadcasts, errors, and invalid IDs.

File	Description
test/​universal_proxy_web/​live/​audio_live_test.exs	Adds facade stubs and tests for pairing-toggle behavior.
lib/​universal_proxy_web/​live/​audio_live.ex	Adds pairing controls, selection state, broadcast handling, and error feedback.

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

Required rpi3 validation with HA 2026.11 and MA 2.11 dev remains outstanding because LiveView tests do not establish end-to-end pairing or HA client_id refresh after switching outputs and reconnecting.

No open issues 🎉

_{Review effort: Balanced}