Harden API input validation, error handling, and optimistic rollbacks

Add try/catch around `request.json()` in all POST routes to return a
400 instead of crashing on malformed bodies. Validate `type` as a
strict `"movie" | "tv"` enum in search, discover, import, and resolve
routes. Validate `tmdbId` as a positive integer. Add a
`SORT_BY_PATTERN` regex and page-range check (1–500) to the discover
route. Wrap all outbound TMDB calls in try/catch and return 502 on
failure so clients get a structured error rather than an unhandled
rejection.

Fix optimistic-update rollbacks in `use-title-actions`: capture
`prevStatus` and `prevWatches` before each mutation and restore both
atoms in the catch block for catchUp, handleMarkSeason,
handleUnmarkSeason, and single-episode toggle.

Fix a bug in `getContinueWatchingFeed` where the watchDateMap could
hold a stale date for episodes watched more than once; the map now
keeps the most-recent `watchedAt` per episode.

lib/services/discovery.ts

@@ -273,9 +273,13 @@ export function getContinueWatchingFeed(
 
   // Build lookup maps
   const watchedEpisodeIds = new Set(allWatches.map((w) => w.episodeId));
-  const watchDateMap = new Map(
-    allWatches.map((w) => [w.episodeId, w.watchedAt]),
-  );
+  const watchDateMap = new Map<string, Date>();
+  for (const watch of allWatches) {
+    const existing = watchDateMap.get(watch.episodeId);
+    if (!existing || watch.watchedAt > existing) {
+      watchDateMap.set(watch.episodeId, watch.watchedAt);
+    }
+  }
 
   // Group seasons by title
   const seasonsByTitle = new Map<string, typeof allSeasons>();

lib/services/metadata.ts

@@ -559,13 +559,29 @@ export async function getTitleWithChildren(id: string): Promise<{
   let titleSeasons: Season[] = [];
 
   if (title.type === "tv") {
-    const seasonRows = db
+    let seasonRows = db
       .select()
       .from(seasons)
       .where(eq(seasons.titleId, title.id))
       .orderBy(seasons.seasonNumber)
       .all();
 
+    // Retry hydration when a TV title exists but no seasons were stored.
+    if (seasonRows.length === 0) {
+      try {
+        const show = await getTvDetails(title.tmdbId);
+        await refreshTvChildren(id, title.tmdbId, show.number_of_seasons);
+        seasonRows = db
+          .select()
+          .from(seasons)
+          .where(eq(seasons.titleId, title.id))
+          .orderBy(seasons.seasonNumber)
+          .all();
+      } catch (err) {
+        log.debug(`Failed to backfill missing seasons for title ${id}:`, err);
+      }
+    }
+
     // Batch fetch all episodes for all seasons (1 query)
     const seasonIds = seasonRows.map((s) => s.id);
     const allEps =

lib/services/tracking.ts

@@ -1,4 +1,4 @@
-import { and, count, eq, inArray, sql } from "drizzle-orm";
+import { and, eq, inArray, sql } from "drizzle-orm";
 import { db } from "@/lib/db/client";
 import {
   episodes,
@@ -183,7 +183,9 @@ function checkAllEpisodesWatched(userId: string, titleId: string) {
 
   const epIds = allEps.map((ep) => ep.id);
   const [watchCount] = db
-    .select({ count: count(userEpisodeWatches.id) })
+    .select({
+      count: sql<number>`count(distinct ${userEpisodeWatches.episodeId})`,
+    })
     .from(userEpisodeWatches)
     .where(
       and(
@@ -343,9 +345,11 @@ export function getEpisodeProgressByTmdbIds(
   const rows = db
     .select({
       tmdbId: titles.tmdbId,
-      totalEpisodes: count(episodes.id),
+      totalEpisodes: sql<number>`count(distinct ${episodes.id})`.as(
+        "totalEpisodes",
+      ),
       watchedEpisodes:
-        sql<number>`sum(case when ${userEpisodeWatches.id} is not null then 1 else 0 end)`.as(
+        sql<number>`count(distinct case when ${userEpisodeWatches.id} is not null then ${episodes.id} end)`.as(
           "watchedEpisodes",
         ),
     })
@@ -417,17 +421,21 @@ export function getUserTitleInfo(userId: string, titleId: string) {
   // Batch fetch all watches for these episodes
   const watchedEpisodeIds =
     epIds.length > 0
-      ? db
-          .select({ episodeId: userEpisodeWatches.episodeId })
-          .from(userEpisodeWatches)
-          .where(
-            and(
-              eq(userEpisodeWatches.userId, userId),
-              inArray(userEpisodeWatches.episodeId, epIds),
-            ),
-          )
-          .all()
-          .map((w) => w.episodeId)
+      ? Array.from(
+          new Set(
+            db
+              .select({ episodeId: userEpisodeWatches.episodeId })
+              .from(userEpisodeWatches)
+              .where(
+                and(
+                  eq(userEpisodeWatches.userId, userId),
+                  inArray(userEpisodeWatches.episodeId, epIds),
+                ),
+              )
+              .all()
+              .map((w) => w.episodeId),
+          ),
+        )
       : [];
 
   return {

lib/services/webhooks.ts

@@ -29,6 +29,17 @@ export interface WebhookEvent {
   showTitle?: string;
 }
 
+function toOptionalInt(value: unknown): number | undefined {
+  if (typeof value === "number" && Number.isInteger(value)) {
+    return value;
+  }
+  if (typeof value === "string" && value.trim().length > 0) {
+    const parsed = Number.parseInt(value, 10);
+    if (!Number.isNaN(parsed)) return parsed;
+  }
+  return undefined;
+}
+
 // ─── Payload Parsers ────────────────────────────────────────────────
 
 export function parsePlexPayload(formData: FormData): WebhookEvent | null {
@@ -63,7 +74,7 @@ export function parsePlexPayload(formData: FormData): WebhookEvent | null {
   if (Array.isArray(guids)) {
     for (const g of guids) {
       const id = g.id ?? "";
-      if (id.startsWith("tmdb://")) tmdbId = Number.parseInt(id.slice(7), 10);
+      if (id.startsWith("tmdb://")) tmdbId = toOptionalInt(id.slice(7));
       else if (id.startsWith("imdb://")) imdbId = id.slice(7);
       else if (id.startsWith("tvdb://")) tvdbId = id.slice(7);
     }
@@ -73,11 +84,11 @@ export function parsePlexPayload(formData: FormData): WebhookEvent | null {
     provider: "plex",
     mediaType: isMovie ? "movie" : "episode",
     title: (metadata.title ?? metadata.Title ?? "") as string,
-    tmdbId: tmdbId && !Number.isNaN(tmdbId) ? tmdbId : undefined,
+    tmdbId,
     imdbId,
     tvdbId,
-    seasonNumber: metadata.parentIndex as number | undefined,
-    episodeNumber: metadata.index as number | undefined,
+    seasonNumber: toOptionalInt(metadata.parentIndex),
+    episodeNumber: toOptionalInt(metadata.index),
     showTitle: (metadata.grandparentTitle ?? metadata.parentTitle) as
       | string
       | undefined,
@@ -96,18 +107,17 @@ export function parseJellyfinPayload(
   const isEpisode = itemType === "Episode";
   if (!isMovie && !isEpisode) return null;
 
-  const tmdbRaw = body.Provider_tmdb as string | undefined;
-  const tmdbId = tmdbRaw ? Number.parseInt(tmdbRaw, 10) : undefined;
+  const tmdbId = toOptionalInt(body.Provider_tmdb);
 
   return {
     provider: "jellyfin",
     mediaType: isMovie ? "movie" : "episode",
     title: (body.Name ?? "") as string,
-    tmdbId: tmdbId && !Number.isNaN(tmdbId) ? tmdbId : undefined,
+    tmdbId,
     imdbId: (body.Provider_imdb as string) || undefined,
     tvdbId: (body.Provider_tvdb as string) || undefined,
-    seasonNumber: body.SeasonNumber as number | undefined,
-    episodeNumber: body.EpisodeNumber as number | undefined,
+    seasonNumber: toOptionalInt(body.SeasonNumber),
+    episodeNumber: toOptionalInt(body.EpisodeNumber),
     showTitle: (body.SeriesName ?? body.ShowName) as string | undefined,
   };
 }
@@ -129,18 +139,17 @@ export function parseEmbyPayload(
   if (!isMovie && !isEpisode) return null;
 
   const providerIds = (item.ProviderIds ?? {}) as Record<string, string>;
-  const tmdbRaw = providerIds.Tmdb;
-  const tmdbId = tmdbRaw ? Number.parseInt(tmdbRaw, 10) : undefined;
+  const tmdbId = toOptionalInt(providerIds.Tmdb);
 
   return {
     provider: "emby",
     mediaType: isMovie ? "movie" : "episode",
     title: (item.Name ?? "") as string,
-    tmdbId: tmdbId && !Number.isNaN(tmdbId) ? tmdbId : undefined,
+    tmdbId,
     imdbId: providerIds.Imdb || undefined,
     tvdbId: providerIds.Tvdb || undefined,
-    seasonNumber: item.ParentIndexNumber as number | undefined,
-    episodeNumber: item.IndexNumber as number | undefined,
+    seasonNumber: toOptionalInt(item.ParentIndexNumber),
+    episodeNumber: toOptionalInt(item.IndexNumber),
     showTitle: (item.SeriesName ?? item.ShowName) as string | undefined,
   };
 }