Enrich IQDB candidates; link downloads the e621 original

- IQDB responses carry no preview/file data, so candidates only showed an
  ID; the SPA now enriches them with one batched posts lookup (preview,
  rating, score, favourites, dimensions, tag preview)
- Candidate tiles are selectable instead of instantly resolving: picking
  one shows its info and an explicit 'Link selected post' button
- Linking a post now fetches the e621 original into the library and
  drops the staged upload; when the staged file's MD5 already equals the
  post's file, the staged copy is moved instead (identical bytes)
- Keep the file URL in stored e621 metadata; sanitize the new candidate
  fields server-side

frontend/src/features/upload/UploadPage.tsx

@@ -17,6 +17,7 @@ import {
   fetchPost,
   fetchPostsByMd5,
   iqdbSearch,
+  RATING_LABELS,
 } from "@/lib/e621";
 import { formatBytes } from "@/lib/format";
 import type {
@@ -45,6 +46,12 @@ const RESOLUTION_LABELS: Record<string, string> = {
   custom: "custom metadata",
 };
 
+const ratingPill: Record<string, string> = {
+  s: "bg-ctp-green text-ctp-crust",
+  q: "bg-ctp-peach text-ctp-crust",
+  e: "bg-ctp-red text-ctp-crust",
+};
+
 const ratingChoices: { value: Rating; label: string; active: string }[] = [
   {
     value: "",
@@ -205,6 +212,7 @@ function MetadataModal({
   const credentials = useE621((state) => state.credentials);
   const [tab, setTab] = useState<"link" | "custom">("link");
   const [postId, setPostId] = useState("");
+  const [selected, setSelected] = useState<E621IqdbCandidate | null>(null);
   const [rating, setRating] = useState<Rating>(temp.custom_rating);
   const [tags, setTags] = useState(temp.custom_tags.join(", "));
   const [notes, setNotes] = useState(temp.custom_notes);
@@ -354,17 +362,39 @@ function MetadataModal({
                           key={`${candidate.post_id}-${candidate.md5}`}
                           type="button"
                           disabled={busy || !candidate.post_id}
-                          onClick={() => void linkCandidate(candidate)}
-                          className="overflow-hidden rounded-md border border-ctp-surface0 bg-ctp-mantle text-left transition hover:border-ctp-surface2 disabled:opacity-50"
+                          onClick={() => setSelected(candidate)}
+                          className={cn(
+                            "overflow-hidden rounded-md border bg-ctp-mantle text-left transition disabled:opacity-50",
+                            selected?.post_id === candidate.post_id
+                              ? "border-ctp-mauve ring-2 ring-ctp-mauve/40"
+                              : "border-ctp-surface0 hover:border-ctp-surface2",
+                          )}
                         >
-                          {candidate.preview_url ? (
-                            <img
-                              src={candidate.preview_url}
-                              alt={`Post #${candidate.post_id}`}
-                              loading="lazy"
-                              className="aspect-square w-full object-cover"
-                            />
-                          ) : null}
+                          <span className="relative block aspect-square overflow-hidden">
+                            {candidate.preview_url ? (
+                              <img
+                                src={candidate.preview_url}
+                                alt={`Post #${candidate.post_id}`}
+                                loading="lazy"
+                                className="h-full w-full object-cover"
+                              />
+                            ) : (
+                              <span className="flex h-full w-full items-center justify-center text-[10px] text-ctp-overlay0">
+                                No preview
+                              </span>
+                            )}
+                            {candidate.rating ? (
+                              <span
+                                className={cn(
+                                  "absolute left-1 top-1 rounded-full px-1 py-0.5 font-mono text-[9px] font-semibold uppercase",
+                                  ratingPill[candidate.rating] ??
+                                    "bg-ctp-surface1 text-ctp-text",
+                                )}
+                              >
+                                {candidate.rating}
+                              </span>
+                            ) : null}
+                          </span>
                           <span className="block px-1.5 py-1 font-mono text-[10px] text-ctp-overlay0">
                             #{candidate.post_id}
                             {candidate.score !== null
@@ -374,6 +404,62 @@ function MetadataModal({
                         </button>
                       ))}
                     </div>
+
+                    {selected ? (
+                      <div className="mt-2 rounded-md border border-ctp-surface0 bg-ctp-surface0/40 p-3">
+                        <p className="font-mono text-xs text-ctp-subtext1">
+                          Post #{selected.post_id}
+                        </p>
+                        <p className="mt-1 text-xs text-ctp-overlay0">
+                          {selected.rating
+                            ? (RATING_LABELS[selected.rating] ?? selected.rating)
+                            : "Unknown rating"}
+                          {selected.score_total !== null &&
+                          selected.score_total !== undefined
+                            ? ` · ▲ ${selected.score_total}`
+                            : ""}
+                          {selected.fav_count !== null &&
+                          selected.fav_count !== undefined
+                            ? ` · ${selected.fav_count} favs`
+                            : ""}
+                          {selected.width && selected.height
+                            ? ` · ${selected.width}×${selected.height}`
+                            : ""}
+                        </p>
+                        {selected.tags_preview &&
+                        selected.tags_preview.length > 0 ? (
+                          <div className="mt-2 flex flex-wrap gap-1">
+                            {selected.tags_preview.map((tag) => (
+                              <span
+                                key={tag}
+                                className="rounded border border-ctp-surface1 px-1 py-0.5 font-mono text-[10px] text-ctp-subtext0"
+                              >
+                                {tag}
+                              </span>
+                            ))}
+                          </div>
+                        ) : null}
+                        <div className="mt-3 flex items-center gap-3">
+                          <Button
+                            onClick={() => void linkCandidate(selected)}
+                            disabled={busy || !selected.post_id}
+                          >
+                            Link selected post
+                          </Button>
+                          <Link
+                            to={`/detail/${selected.post_id}`}
+                            target="_blank"
+                            className="text-xs text-ctp-blue hover:underline"
+                          >
+                            View post
+                          </Link>
+                        </div>
+                        <p className="mt-2 text-[11px] text-ctp-overlay0">
+                          Linking downloads the post's file into the library and
+                          drops this staged upload.
+                        </p>
+                      </div>
+                    ) : null}
                   </div>
                 ) : (
                   <p className="text-xs text-ctp-overlay0">

frontend/src/lib/e621.ts

@@ -322,6 +322,26 @@ export interface E621IqdbResult {
   preview_url: string | null;
   rating: string | null;
   md5: string | null;
+  score_total: number | null;
+  fav_count: number | null;
+  width: number | null;
+  height: number | null;
+  tags_preview: string[];
+}
+
+function flattenTagPreview(tags: unknown, limit = 8): string[] {
+  if (!tags || typeof tags !== "object") return [];
+  const out: string[] = [];
+  for (const value of Object.values(tags as Record<string, unknown>)) {
+    if (!Array.isArray(value)) continue;
+    for (const tag of value) {
+      if (typeof tag === "string" && !out.includes(tag)) {
+        out.push(tag);
+        if (out.length >= limit) return out;
+      }
+    }
+  }
+  return out;
 }
 
 function normalizeIqdbEntry(entry: unknown): E621IqdbResult | null {
@@ -344,12 +364,18 @@ function normalizeIqdbEntry(entry: unknown): E621IqdbResult | null {
       : typeof post.id === "number"
         ? post.id
         : null;
+  const scoreTotal = post.score;
   return {
     post_id: postId,
     score: typeof record.score === "number" ? record.score : null,
     preview_url: typeof preview.url === "string" ? preview.url : null,
     rating: typeof post.rating === "string" ? post.rating : null,
     md5: typeof file.md5 === "string" ? file.md5 : null,
+    score_total: typeof scoreTotal === "number" ? scoreTotal : null,
+    fav_count: typeof post.fav_count === "number" ? post.fav_count : null,
+    width: typeof file.width === "number" ? file.width : null,
+    height: typeof file.height === "number" ? file.height : null,
+    tags_preview: flattenTagPreview(post.tags),
   };
 }
 
@@ -371,13 +397,44 @@ export async function iqdbSearch(
     : Array.isArray((data as { matches?: unknown[] })?.matches)
       ? (data as { matches: unknown[] }).matches
       : [];
-  return list
+  const candidates = list
     .map(normalizeIqdbEntry)
     .filter(
       (entry): entry is E621IqdbResult =>
         entry !== null && (entry.post_id !== null || entry.preview_url !== null),
     )
     .slice(0, 10);
+
+  // The IQDB payload carries no preview/file data; enrich with one batched
+  // post lookup so candidates can show what they actually are.
+  const ids = candidates
+    .map((candidate) => candidate.post_id)
+    .filter((id): id is number => typeof id === "number");
+  if (ids.length > 0) {
+    try {
+      const posts = await fetchPostsByIds(credentials, ids, signal);
+      const byId = new Map(posts.map((post) => [post.id, post]));
+      return candidates.map((candidate) => {
+        const post =
+          candidate.post_id !== null ? byId.get(candidate.post_id) : undefined;
+        if (!post) return candidate;
+        return {
+          ...candidate,
+          preview_url: post.preview.url ?? candidate.preview_url,
+          rating: post.rating ?? candidate.rating,
+          md5: post.file.md5 ?? candidate.md5,
+          score_total: post.score.total,
+          fav_count: post.fav_count,
+          width: post.file.width,
+          height: post.file.height,
+          tags_preview: flattenTagPreview(post.tags),
+        };
+      });
+    } catch {
+      // Keep the base candidates when the enrichment request fails.
+    }
+  }
+  return candidates;
 }
 
 export function postIsBlacklisted(

frontend/src/lib/types.ts

@@ -113,6 +113,11 @@ export interface E621IqdbCandidate {
   preview_url: string | null;
   rating: string | null;
   md5: string | null;
+  score_total?: number | null;
+  fav_count?: number | null;
+  width?: number | null;
+  height?: number | null;
+  tags_preview?: string[];
 }
 
 export interface TempUpload {