Ads: generated spots never get background music — the worker writes BedMediaId null, so the promised ducked bed (Ads:BedDuckDb) never plays

[genwave-radio]

What airs

Every generated spot is dry voice. "No jingles are being ducked as promised."

Why

• src/GenWave.Ads/AdSpotWorker.cs:289, 301 — BedMediaId: null on every worker-written row. The bed path exists only for owner drafts through the editor's BedPicker (AdRenderService.ResolveBedAsync, Ads:BedDuckDb −12 dB; F161.2 "mixes an optional bed"; the v5.6.0 changelog promises the same).
• There is no bed source to pick from: the demo library has no bed/jingle material at all (imaging kinds today: ad ×12, liner ×2); briefs and packs carry no bed.

Ruling (Dean, 2026-09-06)

Generated spots get background music, ducked under the voices.

Source ruling (Dean, 2026-09-06)

Background music comes from jingle packs — a coming catalog kind in its own epic (the ad-pack / font-pack shape: community-shelf entries carrying licensed short instrumentals and station jingles). This issue is the consumer side and is sequenced after that epic: the worker's per-spot pick reads from installed jingle packs, so the bed pool, its licence handling and the shelf UI belong to the packs epic, not here. Until then a spot without an installed pack stays dry (no synthetic bed, no bundled CC0 seed).

Fix

• The worker draws a bed deterministically per spot (seeded by spot id) from the installed jingle packs' bed rows and stamps bed_media_id; the existing mixer ducks it by Ads:BedDuckDb, cue-trimmed to the voice length with a short tail fade. No pack installed → no bed, logged once per tick at Information.
• Editor: the BedPicker shows the automatic pick; an owner override wins.
• Word choice: the UI says "Background music", not "bed" — see the jargon issue UI/docs: radio jargon ("bed", "liner", "imaging", "ident", "patter") needs a plain name or a one-line explanation wherever it appears #707.

Acceptance

A worker-written ready row has bed_media_id; the rendered file carries music under the voice at the configured duck; the ear.

Epic: #380

[genwave-radio]

Moved from the launch ship list to post-launch (2026-09-22, launch-polish /explore). Beds for generated spots are an enhancement the demo has never aired, so no stranger misses them on day one; the sound cluster shipping before 10-31 is #699 #712 #700 #703 #701 #742 #706 #773. Lands in the Ads polish group of the first post-launch epic; the jingle-pack source it was sequenced behind (#709) shipped in v5.7.0, so nothing blocks it then.