docs(72): record the channel-health API shape + mirror the lineup fault state

Same-PR docs obligations for #72:

- decisions.md — why health is the raw `PlayoutCount` fact on the lean list DTO
  rather than a derived status enum or a new endpoint, and, more importantly,
  why empty-schedule / broken-source / auto-tuned-origin are deliberately NOT
  computed. The empty-schedule one is the trap worth writing down: it only
  understands Classic ProgramSchedule playouts, so a badge driven off it would
  silently lie on the other four schedule kinds.
- domain-model.md — a glossary row for channel health, drawing the line against
  /channels/state's OnAir (runtime liveness, not "would play if tuned").
- design-system — mirror the "No playout" badge + Problems filter into the
  Channels prototype so design-system/ stays a faithful mirror of prod
  (design-sync #388). Nature Docs carries playouts: 0 so the fault state is
  visible in the canvas.

Refs #72

design-system/templates/chicorytv-admin/Channels.jsx

@@ -31,6 +31,7 @@
     let rows = D.channels;
     if (view === "onair") rows = rows.filter((c) => c.live);
     else if (view === "disabled") rows = rows.filter((c) => !c.enabled);
+    else if (view === "problems") rows = rows.filter((c) => c.playouts === 0);
 
     // group, preserving first-seen order
     const groups = [];
@@ -43,11 +44,11 @@
     const toggleAll = () => { if (allOn) setSel({}); else { const n = {}; rows.forEach((c) => (n[c.num] = true)); setSel(n); } };
     const toggleOne = (num) => setSel((s) => ({ ...s, [num]: !s[num] }));
 
-    const counts = { all: D.channels.length, onair: D.channels.filter((c) => c.live).length, disabled: D.channels.filter((c) => !c.enabled).length };
+    const counts = { all: D.channels.length, onair: D.channels.filter((c) => c.live).length, disabled: D.channels.filter((c) => !c.enabled).length, problems: D.channels.filter((c) => c.playouts === 0).length };
 
     const Segmented = () => (
       <div style={{ display: "inline-flex", gap: 2, padding: 2, borderRadius: "var(--radius-sm)", background: "var(--ctv-bg-sunken)", border: "1px solid var(--border-hairline)" }}>
-        {[{ v: "all", l: "All", c: counts.all }, { v: "onair", l: "On air", c: counts.onair }, { v: "disabled", l: "Disabled", c: counts.disabled }].map((o) => {
+        {[{ v: "all", l: "All", c: counts.all }, { v: "onair", l: "On air", c: counts.onair }, { v: "disabled", l: "Disabled", c: counts.disabled }, { v: "problems", l: "Problems", c: counts.problems }].map((o) => {
           const on = o.v === view;
           return (
             <button key={o.v} type="button" onClick={() => setView(o.v)}
@@ -83,6 +84,7 @@
                   <span style={{ font: "var(--weight-medium) var(--text-sm)/1.2 var(--font-sans)", color: "var(--text-primary)" }}>{c.name}</span>
                   {!c.enabled && <Marker title="Disabled">D</Marker>}
                   {!c.epg && <Marker title="Hidden from EPG">H</Marker>}
+                  {c.playouts === 0 && <Badge tone="error">No playout</Badge>}
                 </div>
                 <div style={{ marginTop: 3, font: "var(--text-2xs)/1 var(--font-sans)", color: "var(--text-disabled)" }}>{c.lang}</div>
               </div>

design-system/templates/chicorytv-admin/data.js

@@ -3,15 +3,15 @@
 
 window.CTV_DATA = {
   channels: [
-    { num: "1.1",  name: "Retro Cartoons",   group: "Cartoons", lang: "English", mode: "HLS Segmenter", profile: "1080p H.264", live: true,  enabled: true,  epg: true },
-    { num: "1.2",  name: "Anime Block",      group: "Cartoons", lang: "Japanese",mode: "HLS Segmenter", profile: "1080p H.264", live: false, enabled: true,  epg: true },
-    { num: "2.1",  name: "News 24",          group: "News",     lang: "English", mode: "HLS Segmenter", profile: "720p H.264",  live: true,  enabled: true,  epg: true },
-    { num: "3.1",  name: "Late Night Movies",group: "Movies",   lang: "English", mode: "MPEG-TS",       profile: "1080p HEVC",  live: false, enabled: true,  epg: true },
-    { num: "7.3",  name: "Sci-Fi Marathon",  group: "Movies",   lang: "English", mode: "MPEG-TS",       profile: "1080p H.264", live: false, enabled: true,  epg: false },
-    { num: "4.2",  name: "Music Videos",     group: "Music",    lang: "English", mode: "HLS Segmenter", profile: "720p H.264",  live: true,  enabled: true,  epg: true },
-    { num: "5.1",  name: "Nature Docs",      group: "Docs",     lang: "Spanish", mode: "HLS Direct",    profile: "—",           live: false, enabled: true,  epg: true },
-    { num: "9.1",  name: "Kids Block",       group: "Kids",     lang: "French",  mode: "HLS Segmenter", profile: "720p H.264",  live: true,  enabled: true,  epg: true },
-    { num: "12.1", name: "Test Pattern",     group: "System",   lang: "English", mode: "MPEG-TS",       profile: "480p H.264",  live: false, enabled: false, epg: false },
+    { num: "1.1",  name: "Retro Cartoons",   group: "Cartoons", lang: "English", mode: "HLS Segmenter", profile: "1080p H.264", live: true,  enabled: true,  epg: true, playouts: 1 },
+    { num: "1.2",  name: "Anime Block",      group: "Cartoons", lang: "Japanese",mode: "HLS Segmenter", profile: "1080p H.264", live: false, enabled: true,  epg: true, playouts: 1 },
+    { num: "2.1",  name: "News 24",          group: "News",     lang: "English", mode: "HLS Segmenter", profile: "720p H.264",  live: true,  enabled: true,  epg: true, playouts: 1 },
+    { num: "3.1",  name: "Late Night Movies",group: "Movies",   lang: "English", mode: "MPEG-TS",       profile: "1080p HEVC",  live: false, enabled: true,  epg: true, playouts: 1 },
+    { num: "7.3",  name: "Sci-Fi Marathon",  group: "Movies",   lang: "English", mode: "MPEG-TS",       profile: "1080p H.264", live: false, enabled: true,  epg: false, playouts: 1 },
+    { num: "4.2",  name: "Music Videos",     group: "Music",    lang: "English", mode: "HLS Segmenter", profile: "720p H.264",  live: true,  enabled: true,  epg: true, playouts: 1 },
+    { num: "5.1",  name: "Nature Docs",      group: "Docs",     lang: "Spanish", mode: "HLS Direct",    profile: "—",           live: false, enabled: true,  epg: true, playouts: 0 },
+    { num: "9.1",  name: "Kids Block",       group: "Kids",     lang: "French",  mode: "HLS Segmenter", profile: "720p H.264",  live: true,  enabled: true,  epg: true, playouts: 1 },
+    { num: "12.1", name: "Test Pattern",     group: "System",   lang: "English", mode: "MPEG-TS",       profile: "480p H.264",  live: false, enabled: false, epg: false, playouts: 1 },
   ],
   playoutItems: [
     { start: "20:00:00", finish: "20:24:00", title: "Looney Tunes — Rabbit Fire",        dur: "00:24:00", kind: "content" },

docs/decisions.md

@@ -86,6 +86,7 @@ in-file entries.
 - [2026-07-17 — Clock-boundary schedule padding already exists (FillerMode.Pad); #77 verified, convenience toggle deferred](#2026-07-17--clock-boundary-schedule-padding-already-exists-fillermodepad-77-verified-convenience-toggle-deferred)
 - [2026-07-17 — Shuffle-source construction extracted to `ShuffleSourceBuilder`; per-family seam, not a god-factory (#380)](#2026-07-17--shuffle-source-construction-extracted-to-shufflesourcebuilder-per-family-seam-not-a-god-factory-380)
 - [2026-07-17 — Seasonal / date-conditional scheduling already exists (alternate schedules / playout templates); #73 closed as implemented](#2026-07-17--seasonal--date-conditional-scheduling-already-exists-alternate-schedules--playout-templates-73-closed-as-implemented)
+- [2026-07-17 — Channel health on the API = the raw `PlayoutCount` fact on the list DTO, not a derived status enum (#72)](#2026-07-17--channel-health-on-the-api--the-raw-playoutcount-fact-on-the-list-dto-not-a-derived-status-enum-72)
 
 ---
 
@@ -1198,3 +1199,49 @@ channel" has no reason to look under "Alternate Schedules", and on finding that
 Fixed with a task-shaped **"Recipe: seasonal / holiday programming"** section in `channels.md` (both engines,
 plus the gotchas above) and a `domain-model.md` glossary row. No production code changed, so no live-E2E
 (same reasoning as #77).
+
+---
+
+## 2026-07-17 — Channel health on the API = the raw `PlayoutCount` fact on the list DTO, not a derived status enum (#72)
+
+#72 asks for per-channel status in the Channels list, "especially channels that will fail to play".
+
+**Where it lives: `ChannelResponseModel` (the lean list DTO), not a new endpoint and not
+`/channels/state`.** Channel health is *config-derived* — it changes when someone edits a playout, not
+tick to tick — whereas `/channels/state` is the fast-poll runtime-liveness feed (`OnAir` = someone is
+streaming *right now*). Folding health into the polled feed would recompute rarely-changing data every
+tick and mix two cadences in one DTO; a third endpoint is over-engineering for one derived integer on a
+list whose consumer already reads it. Precedent: `api-conventions.md` §3a stamps the server-derived
+`IsLocked` onto `PlayoutListItemResponseModel` for exactly this reason. **It is also free**: `GetAll`
+already `Include`s `Playouts` and `MirrorSourceChannel.Playouts` and was discarding them, so no extra
+query and no N+1 on a large lineup.
+
+**A raw fact (`int PlayoutCount`), not a `ChannelHealth` enum.** v1 has exactly one trustworthy negative
+signal, and the auto-tune arc (#383/#384) is about to churn the status taxonomy (origin, auto-tune
+outcomes) — freezing a server-side enum now guarantees a breaking rev of a frozen-additive `/api/v1`
+surface. `PlayoutCount` mirrors the long-standing `ChannelViewModel.PlayoutCount` 1:1, is a fact rather
+than a policy, and leaves the SPA to derive `0 ⇒ "No playout"` in one predicate.
+
+**What v1 deliberately does NOT compute** — each was considered and ruled out, so don't "finish" them
+without reading this:
+- **Empty schedule behind an existing playout.** `EmptyScheduleHealthCheck` only understands **Classic**
+  `ProgramSchedule` playouts. Block, Sequential, Scripted and ExternalJson channels have no
+  `ProgramSchedule` at all, so a badge driven off that query would be silently absent or wrong for four of
+  the five schedule kinds — the #71 "verify a shared primitive covers ALL variants" trap. Needs a
+  per-kind emptiness notion first.
+- **Broken / missing source.** `FileNotFound`/`Unavailable` are server-wide media-item counts with no
+  channel attribution; mapping media → collection → schedule → channel is a project, not a field.
+- **User-defined vs auto-generated origin** (#72 scope item a). No honest signal exists:
+  `Channel` has no origin column, and `ChannelPlayoutSource.Generated` is a *playout-strategy* value that
+  SPA-created blank channels also carry, so it would mislabel them. Requires a new column + a dual-provider
+  migration, and provenance belongs to the auto-tune arc that stamps it at creation. A join through the
+  `"Channel Lineups"` system playlist group was **rejected**: it is a heuristic that breaks the moment a
+  user edits the channel. Deferred to a follow-up blocked on the auto-tune backend.
+
+Keeping all three out held #72 to a **read-path-only** change: no migration, no write-handler live-E2E.
+
+**Corrected in passing:** `ChannelRepository.GetChannel` never included `Playouts`, so
+`GET /api/v1/channels/{id}` reported `playoutCount: 0` for every channel, which silently disabled the
+channel editor's playout-source guard. Both call sites now share `Mapper.GetPlayoutsCount` (Mirror-aware).
+The related *silent* server-side coercion of Mirror→Generated (a 200 that discards the caller's intent,
+against the §3 "surface it, don't silently filter" rule) is filed as **#401**, not fixed here.

docs/domain-model.md

@@ -79,6 +79,7 @@ Channel (1) ──< Playout (0..N per channel; ChannelPlayoutSource distinguishe
 | **PlayoutItem** | One materialized, built entry in a playout's timeline (the actual thing that will play at a given time). | `PlayoutItem` | (generated, not directly edited) |
 | **PlayoutHistory** | Rotation/rerun bookkeeping per block (`BlockId`) + collection `Key`/`ChildKey`, used by block-playout schedulers to avoid repeats; inspectable via Troubleshooting. | `PlayoutHistory` | `/app/troubleshooting/blocks` |
 | **Channel concepts** | `Number` (validated by `Channel.NumberValidator` regex), `Group`, `PlayoutSource` (Generated/Mirror; Mirror channels relay another channel via `MirrorSourceChannelId`+`PlayoutOffset`), `PlayoutMode` (Continuous/OnDemand), `TranscodeMode` (OnDemand only, today), `IdleBehavior` (StopOnDisconnect/KeepRunning), `StreamingMode` (TransportStream/HttpLiveStreamingDirect/HttpLiveStreamingSegmenter/TransportStreamHybrid). | `Channel` | `/app/channels`, `/app/edit-channel/{id}`, `/app/new-channel`, `/app/auto-tune` (bulk-generate from library metadata, #69) |
+| **Channel health / `PlayoutCount`** (#72) | Whether a channel can play at all. `PlayoutCount` (channel's own playouts, **plus the mirror source's** when `PlayoutSource is Mirror` — computed by `Mapper.GetPlayoutsCount`) rides on both `ChannelResponseModel` (list) and `ChannelDetailResponseModel`; `0` ⇒ the channel can never play, rendered as a "No playout" badge + a **Problems** filter on the channels list. It is a **raw fact, not a status enum** — see `decisions.md` 2026-07-17. Distinct from `/api/v1/channels/state`'s `OnAir`, which is runtime liveness ("someone is streaming right now"), not "would play if tuned". Empty-schedule, broken-source and auto-tuned-vs-user origin are deliberately **not** computed (see that decision entry for why each is unsafe today). | `Channel.Playouts` | `/app/channels` (read-only signal) |
 | **Guide / EPG (XMLTV)** | Per-channel programme guide generated from playout items; channels with `ShowInEpg=false` are excluded. | `GetChannelGuideHandler` | `/app/guide` (viewer); settings at `/app/settings/xmltv` |
 | **M3U** | The channel lineup playlist Jellyfin/Dispatcharr consume. | `ChannelPlaylist.ToM3U()` | — |
 | **IPTV base URL** | Optional advertised base URL for the IPTV surface (#340). Stored as a single `ConfigElement` (`ConfigElementKey.IptvBaseUrl`, key `iptv.base_url`, no EF migration); when set, `GetChannelPlaylistHandler` (M3U) and `GetChannelGuideHandler` (XMLTV) pin their absolute URLs to its scheme/host/base instead of the request `Host` (blank/invalid → request-derived). Not applied to HDHomeRun; distinct from `ETV_BASE_URL`. Parsed by `ErsatzTV.Core/Iptv/AdvertisedBaseUrl.cs`. | `ConfigElementKey.IptvBaseUrl` | `/app/settings` → IPTV (`GET`/`PUT /api/v1/settings/iptv`) |