fix(preview): guard want() on res.ok; docs: preview in README + artists-search TODO

- preview-client want() no longer flips the Monitored badge when the POST fails
  (deferred item #1 from the discovery-preview whole-branch review).
- README: discovery section notes the artist preview page.
- Plan Notes + project-state: TODO to reuse the preview page from the /artists
  live search (wire artists-client.tsx hits to /discover/artist/[mbid]).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -27,8 +27,11 @@ Built in three slices:
    aggregates artists similar to the ones you follow into a manual review feed of
    suggested **artists** and **albums** at `/discover`; **Follow** and **Want**
    reuse the slice-2 follow / wanted flows, **Dismiss** is permanent. Plus a
-   web-side seed-search box. No Spotify (its recommendation APIs are dead for new
-   apps).
+   web-side seed-search box. Every suggestion and seed-search result opens a
+   read-only **artist preview** (`/discover/artist/[mbid]`) — discography,
+   per-album tracklists, and "in library" / "monitored" badges — where you can
+   Follow or Want before committing. No Spotify (its recommendation APIs are dead
+   for new apps).
 
 **Operational notes:** the monitor and the discovery sweep are both **off by
 default** — set `monitor.enabled=true` (+ optional `monitor.*` tuning) in the

docs/superpowers/plans/2026-07-12-lyra-discovery-preview.md

@@ -836,3 +836,5 @@ Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>"
 - Tracklists are fetched live per expand; a short-lived cache (or persisting on Want) is a later option if MB rate-limiting bites.
 - The preview shows one representative release's tracklist; multi-disc/edition differences aren't surfaced.
 - `have` via `LibraryItem` matches on `(artistName, album)` (name-based, like the existing wanted-add path); MBID-based library matching is a broader future change.
+- **TODO — reuse the preview page from the normal `/artists` live search.** The artists search→follow picker (`artists-client.tsx`) currently only follows; wire each MB search hit to also link to `/discover/artist/[mbid]?name=…` so you can preview (disco + tracklists + own-state) before following there too. The preview page + endpoints already exist — this is a small link-wiring task in `artists-client.tsx`.
+- **Applied post-merge:** `want()` in `preview-client.tsx` now guards on `res.ok` before optimistically flipping the Monitored badge (was deferred item #1 from the whole-branch review).

web/src/app/discover/artist/[mbid]/preview-client.tsx

@@ -65,7 +65,7 @@ export function PreviewClient({ mbid, initialName }: { mbid: string; initialName
   }
 
   async function want(r: Release) {
-    await fetch("/api/discover/want", {
+    const res = await fetch("/api/discover/want", {
       method: "POST",
       headers: { "content-type": "application/json" },
       body: JSON.stringify({
@@ -78,6 +78,7 @@ export function PreviewClient({ mbid, initialName }: { mbid: string; initialName
         firstReleaseDate: r.firstReleaseDate,
       }),
     });
+    if (!res.ok) return; // don't flip the badge if the want failed
     setData((d) =>
       d ? { ...d, releases: d.releases.map((x) => (x.rgMbid === r.rgMbid ? { ...x, monitored: true } : x)) } : d,
     );