Flag slave-only songs whose album or artist the master has

Scans now mark slave-only songs as missing from the master when the master
has their album folder or at least their artist folder. A new Missing from
master filter in Review lists them, split by album and artist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/api.ts

@@ -57,6 +57,7 @@ export type Summary = {
   review: number;
   upgrades: number;
   ignored: number;
+  missing?: { album?: number; artist?: number };
   reclaimable_bytes: number;
   linked_bytes: number;
 };
@@ -132,6 +133,7 @@ export type Match = {
   verdict?: Verdict;
   note: string;
   reason: string;
+  missing: "" | "album" | "artist";
   link_target: string;
   ignored: boolean;
 };

web/src/pages/Review.tsx

@@ -1,6 +1,6 @@
 import { useEffect, useState } from "react";
 import { keepPreviousData, useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
-import { AlertTriangle, ArrowRight, ArrowUpCircle, Disc3, Download, ListMusic, ChevronDown, ChevronRight, CopyCheck, CopyMinus, EyeOff, Eye, Link2, Search, Crown } from "lucide-react";
+import { AlertTriangle, ArrowRight, ArrowUpCircle, Disc3, Download, FolderSearch, ListMusic, ChevronDown, ChevronRight, CopyCheck, CopyMinus, EyeOff, Eye, Link2, Search, Crown } from "lucide-react";
 import { ApiError, api, type Match, type Page, type Pair, type ProbeInfo } from "../api";
 import { Alert, Badge, Button, Card, Empty, Modal, Spinner, cx, formatBytes, formatDuration, inputCls, statusTone } from "../ui";
 import { useToast } from "../toast";
@@ -13,6 +13,7 @@ const filters = [
   { id: "identical", label: "Identical" },
   { id: "linked", label: "Linked" },
   { id: "unmatched", label: "Slave only" },
+  { id: "missing", label: "Missing from master" },
   { id: "error", label: "Errors" },
   { id: "ignored", label: "Ignored" },
   { id: "", label: "All" },
@@ -86,8 +87,21 @@ export function Review({ pair }: { pair: Pair }) {
   });
 
   const c = pair.summary.counts;
+  const miss = pair.summary.missing ?? {};
   const count = (id: string) =>
-    id === "review" ? pair.summary.review : id === "upgrade" ? pair.summary.upgrades : id === "ignored" ? pair.summary.ignored : id === "" ? undefined : c[id] ?? 0;
+    id === "review"
+      ? pair.summary.review
+      : id === "upgrade"
+        ? pair.summary.upgrades
+        : id === "ignored"
+          ? pair.summary.ignored
+          : id === "missing"
+            ? (miss.album ?? 0) + (miss.artist ?? 0)
+            : id === ""
+              ? undefined
+              : c[id] ?? 0;
+  // The missing filter has two levels; the chip covers all three.
+  const active = (id: string) => status === id || (id === "missing" && status.startsWith("missing_"));
   const identical = c.identical ?? 0;
   const running = pair.job?.state === "running";
 
@@ -100,7 +114,7 @@ export function Review({ pair }: { pair: Pair }) {
             onClick={() => setStatus(f.id)}
             className={cx(
               "flex items-center gap-1.5 rounded-full border px-3 py-1 text-xs cursor-pointer",
-              status === f.id ? "border-accent bg-accent/15 text-white" : "border-line text-muted hover:text-white",
+              active(f.id) ? "border-accent bg-accent/15 text-white" : "border-line text-muted hover:text-white",
             )}
           >
             {f.label}
@@ -139,7 +153,7 @@ export function Review({ pair }: { pair: Pair }) {
               </button>
             ))}
           </div>
-          <ExportMenu pairId={pair.id} status={status} query={debounced} viewCount={list.data?.total} filterLabel={filters.find((f) => f.id === status)?.label ?? "All"} />
+          <ExportMenu pairId={pair.id} status={status} query={debounced} viewCount={list.data?.total} filterLabel={filters.find((f) => active(f.id))?.label ?? "All"} />
         </div>
         )}
       </div>
@@ -148,6 +162,7 @@ export function Review({ pair }: { pair: Pair }) {
         <Duplicates pair={pair} />
       ) : (
       <>
+      {status.startsWith("missing") && <MissingIntro pair={pair} status={status} setStatus={setStatus} />}
 
       {status === "identical" && identical > 0 && (
         <Card className="flex flex-wrap items-center justify-between gap-3 p-4">
@@ -233,6 +248,50 @@ export function Review({ pair }: { pair: Pair }) {
   );
 }
 
+function MissingIntro({ pair, status, setStatus }: { pair: Pair; status: string; setStatus: (s: string) => void }) {
+  const miss = pair.summary.missing ?? {};
+  const levels = [
+    { id: "missing", label: "All", n: (miss.album ?? 0) + (miss.artist ?? 0) },
+    { id: "missing_album", label: "Album in master", n: miss.album ?? 0 },
+    { id: "missing_artist", label: "Only the artist in master", n: miss.artist ?? 0 },
+  ];
+  return (
+    <Card className="space-y-3 p-4">
+      <div className="flex items-start gap-3">
+        <FolderSearch className="mt-0.5 size-5 shrink-0 text-accent" />
+        <div className="text-sm">
+          <div className="font-medium">Songs the master library is missing</div>
+          <div className="mt-0.5 text-muted">
+            These songs are only in the slave library, but the master has their artist, and often the album too. For example, the slave has{" "}
+            <i>Caravan Palace/Robot Face/Waterguns</i> and the master has the <i>Caravan Palace/Robot Face</i> album without that song. Add them to
+            the master to complete it, then scan again to link them. Nothing here is changed automatically.
+          </div>
+          {!pair.approx_matching && (
+            <div className="mt-1.5 text-xs text-amber-300/90">
+              Approximate matching is off for this pair, so a song filed under a slightly different name or another release (a single vs. the
+              album) shows up here too. Turn it on in Edit to find those.
+            </div>
+          )}
+        </div>
+      </div>
+      <div className="flex flex-wrap gap-1 rounded-lg border border-line p-0.5 sm:w-fit">
+        {levels.map((l) => (
+          <button
+            key={l.id}
+            onClick={() => setStatus(l.id)}
+            className={cx(
+              "flex items-center gap-1.5 rounded-md px-2.5 py-1 text-xs cursor-pointer",
+              status === l.id ? "bg-panel-2 text-white" : "text-muted hover:text-white",
+            )}
+          >
+            {l.label} <span className="tabular-nums opacity-70">{l.n}</span>
+          </button>
+        ))}
+      </div>
+    </Card>
+  );
+}
+
 function ExportMenu({ pairId, status, query, viewCount, filterLabel }: { pairId: number; status: string; query: string; viewCount?: number; filterLabel: string }) {
   const [open, setOpen] = useState(false);
   useEffect(() => {
@@ -335,6 +394,9 @@ export function MatchRow({ m, selected, onToggle }: { m: Match; selected?: boole
         <div className="flex w-28 shrink-0 flex-col items-start gap-1">
           <Badge tone={statusTone[m.status]}>{m.status}</Badge>
           {m.kind !== "path" && m.kind !== "none" && <span className="text-[10px] text-muted">{kindLabel[m.kind]}</span>}
+          {m.status === "unmatched" && m.missing && (
+            <span className="text-[10px] text-amber-300/90">{m.missing === "album" ? "album in master" : "artist in master"}</span>
+          )}
         </div>
         <div className="min-w-0 flex-1" onClick={() => reviewable && setOpen(!open)}>
           <PathLine m={m} />