Add message links, suspect retries, and Discord preview recovery

CURRENT.md

@@ -40,6 +40,19 @@ mobile draft at 390px.
   - [x] C11 preview caching: Discord-hosted image/GIF previews (WebP 320px, hash-addressed, 5 MiB
     cap, one attempt) run after every walk in both modes. Live run `...-20260916090722`:
     `previewed: 2`; thumbs served over `/api/media/<scrape>/<item>/thumb` (200).
+  - [x] C54 Message links, suspect retries, and preview recovery. Items now carry `messageUrl`
+    (from `media_sources` + scrape guild), the viewer shows/copies it instead of the expiring CDN
+    link and opens a fresh stream for View full, YouTube items offer an **Open on YouTube**
+    fallback, and the metadata gained Channel/Scrape/Title (title includes the channel kept from
+    oEmbed, `title_author`). Preview and download HTTP failures on Discord hosts first refresh the
+    URL from the source message and retry; if that fails the row parks as a **suspect** with one
+    delayed retry (50 s, runs after the batch; a batch two-thirds suspect doubles the cooldown,
+    60 s floor). Still-failing rows are **unverified** and skipped by normal passes; the Bot tab
+    shows suspect/unverified counts and a segmented progress bar (cached blue, pending gray,
+    failed red). **Recover Discord previews** is a paused one-shot task that re-fetches every
+    Discord-CDN row closed with an HTTP error across all scrapes (mixed bot/puppet via the
+    existing refresh path) and lands in the task history when done. All 1,208 Discord 404 rows
+    sampled 15/15 recoverable.
   - [x] C53 Title catch-up as its own lane. Titles no longer share the preview batch: a dedicated
     `TitleLane` walks every scrape with a pending title, 100 rows per batch with a 10 s pause
     (hard-coded; it is a one-time catch-up and future titles arrive with the scrape), and takes no

docs/media-scraper.md

@@ -210,6 +210,25 @@ a cached still show a labeled placeholder, and playback streams only when the us
 GIF hover plays the animated GIF cached in `thumbs/` (the original is kept alongside the static
 frame and referenced by `anim_hash`), never the provider, so scrolling cannot spam anyone.
 
+## Failure policy and recovery
+
+The archive never treats a transient HTTP answer as a dead link on the first try.
+
+- A preview or download that fails with an HTTP status on Discord's CDN is retried once with a
+  **refreshed URL** from the source message (the signed link expires in about a day). Only if the
+  refreshed fetch fails is the row parked.
+- Parked rows become **suspects**: they get one delayed retry (about 50 s). The retry runs after
+  the batch, not immediately. If a batch is two-thirds suspect failures, the cooldown doubles
+  (floor 60 s) and the retries run before the next batch.
+- A suspect whose delayed retry fails again is left **unverified**: it is skipped by later passes,
+  so a finished backfill never churns over genuinely unavailable media. The Bot tab shows suspects
+  and unverified counts per member, and the progress bar fills blue for cached, gray for pending,
+  and red for failed rows.
+- **Recover Discord previews** is a one-shot task in the Bot tab: it walks every scrape's
+  Discord-CDN rows closed with HTTP errors, refreshes each URL through the message (slopbot REST or
+  the puppet, whichever the scrape used), and fetches the preview again. It starts paused; when it
+  finishes it moves to the task history. The code stays for reuse.
+
 ## Bot tab settings
 
 The Bot tab owns the tunables; they persist in `preferences.json` and apply to live jobs at once.

docs/media.md

@@ -101,6 +101,9 @@ media-scrape/db/
 - The grid never renders an embed's page URL as media. A direct video file without a preview shows
   a first-frame `<video>` only for playable containers (mp4, webm, m4v); anything else shows a
   labeled placeholder, and a failed image falls back to that placeholder.
+- Every item carries the permanent Discord message link (`messageUrl`) derived from
+  `media_sources`; the viewer shows it (with a copy button) instead of the expiring CDN URL, and
+  "View full" streams through the daemon so the source is refreshed automatically.
 - Every item records who posted it, when, and its dimensions: `author_id`, `author_name`,
   `posted_at`, `width`, `height`, and `aspect_ratio`. In `download` mode a missing resolution is
   filled in with `ffprobe` after the file lands.

docs/webui.md

@@ -166,7 +166,10 @@ box live in Chat, not Call, and the connection stats are not chips yet.
   file, then the CDN URL; videos and audio are link cards with the poster and posted time in the
   tooltip.
 - Bot shows the slopbot connection state, the backfill queue (previews), the **Titles (YouTube)**
-  catch-up lane with its own Start/Pause, and the media tunables. Backfill has
+  catch-up lane with its own Start/Pause, the one-shot **Recover Discord previews** task, the task
+  history, the failure-policy hint, and the media tunables. Media items carry their permanent
+  `messageUrl`; the viewer shows it with a **Copy link** button in the link popup and offers
+  **Open on YouTube** as a fallback for embeds that refuse to play. Backfill has
   totals and an ETA with a Bot/Puppet split, then one job card per chat with its member scrapes,
   per-kind pending, a progress bar, an ETA, and Start/Pause; the header has **Start backfill** and
   **Pause all**. A red banner reads `API timed out, increase timers` during a Discord cooldown. The
@@ -306,6 +309,9 @@ replaceable.
 | GET | `/api/media/titles` | none | Title catch-up lane: state, pending/resolved/failed, throughput, ETA, current scrape |
 | POST | `/api/media/titles/start` | none | Start the title lane |
 | POST | `/api/media/titles/pause` | none | Pause the title lane after the current batch |
+| GET | `/api/media/recover` | none | Recovery task state, remaining Discord-CDN preview failures, counts, and the task history |
+| POST | `/api/media/recover/start` | none | Start the Discord preview recovery task |
+| POST | `/api/media/recover/pause` | none | Pause the recovery task after the current row |
 | GET | `/api/media/authors` | none | Distinct posters across every scrape, with counts |
 | GET | `/api/media/stats` | same filters as `/api/media` | Counts per kind (`image`, `gif`, `video`, `audio`), each with `total`, `downloaded`, `cached`, `notDownloaded` |
 | GET | `/api/media/storage` | none | Usage against the limit, per-kind sizes, `nearLimit`; marks old scrapes when over |

media-scrape/src/backfill.ts

@@ -31,6 +31,10 @@ export interface BackfillMember {
     pending: number;
     cached: number;
     failed: number;
+    /** Preview failures kept for the delayed suspect retry. */
+    suspect: number;
+    /** Suspect rows whose retry failed too. */
+    unverified: number;
     total: number;
     downloaded: number;
     bytes: number;
@@ -154,6 +158,8 @@ export class BackfillQueue {
                 pending: 0,
                 cached: 0,
                 failed: 0,
+                suspect: 0,
+                unverified: 0,
                 total: 0,
                 downloaded: meta.downloaded ?? 0,
                 bytes: 0,
@@ -167,6 +173,8 @@ export class BackfillQueue {
                     member.pending = counts.pending;
                     member.cached = counts.cached;
                     member.failed = counts.failed;
+                    member.suspect = counts.suspect;
+                    member.unverified = counts.unverified;
                     member.total = counts.total;
                     for (const kind of Object.keys(member.pendingByKind) as MediaKind[]) {
                         member.pendingByKind[kind] = counts.byKind[kind].pending;
@@ -408,6 +416,9 @@ export class BackfillQueue {
 
     private async runJob(job: Job): Promise<void> {
         let stalled = 0;
+        // The cooldown doubles when a batch is mostly suspect failures; it stays raised for the
+        // rest of this job so throttling is not immediately forgotten.
+        let pauseMs = this.options.getSettings().batchPauseMs;
 
         while (!job.stop) {
             const group = this.plan(false).get(job.chatId);
@@ -457,8 +468,30 @@ export class BackfillQueue {
                 stalled = 0;
             }
 
-            if (settings.batchPauseMs > 0 && progressed > 0) {
+            // Suspect failures get one delayed retry. When they reach two thirds of a batch the
-                await this.sleep(settings.batchPauseMs);
+            // cooldown doubles (floor 60 s) and the retry runs before the next batch.
+            const suspectThreshold = Math.ceil((settings.batchSize * 2) / 3);
+            if (result.suspect > 0 && result.suspect >= suspectThreshold) {
+                pauseMs = Math.min(300_000, Math.max(60_000, pauseMs * 2));
+                this.options.log?.(
+                    `backfill: ${job.chatId} ${result.suspect} suspect failures, cooldown now ${pauseMs} ms`
+                );
+            }
+
+            if (pauseMs > 0 && (progressed > 0 || result.suspect > 0)) {
+                await this.sleep(pauseMs);
+                if (job.stop) break;
+            }
+
+            if (result.suspect > 0 || result.unverified > 0) {
+                const retried = await this.engine.previewSuspects(
+                    member.scrapeId,
+                    Math.max(2, Math.ceil(settings.batchSize / 2))
+                );
+                this.options.log?.(
+                    `backfill: ${job.chatId} suspect retry: ${retried.cached} recovered, ` +
+                        `${retried.unverified} left unverified`
+                );
             }
         }
 

media-scrape/src/discord-links.ts

@@ -0,0 +1,14 @@
+/*
+ * Permanent Discord links. CDN URLs expire; the message link never does.
+ */
+
+/** `discord.com/channels/<guildId|@me>/<channelId>/<messageId>`, or null without a message. */
+export function messageUrlFor(
+    guildId: string | null,
+    channelId: string,
+    messageId: string | null
+): string | null {
+    if (!messageId) return null;
+    const scope = guildId ?? "@me";
+    return `https://discord.com/channels/${scope}/${channelId}/${messageId}`;
+}

media-scrape/src/embed-preview.ts

@@ -66,7 +66,7 @@ export function ogImageFromHtml(html: string): string | null {
 export async function resolveEmbedTitle(
     url: string,
     options: DownloadOptions = {}
-): Promise<string | null> {
+): Promise<{ title: string; author: string | null } | null> {
     let parsed: URL;
     try {
         parsed = new URL(url);
@@ -80,7 +80,12 @@ export async function resolveEmbedTitle(
     }
 
     const data = await getJson(`https://www.youtube.com/oembed?url=${encodeURIComponent(url)}&format=json`, options);
-    return typeof data?.title === "string" && data.title.trim() ? data.title.trim() : null;
+    if (typeof data?.title !== "string" || !data.title.trim()) return null;
+
+    return {
+        title: data.title.trim(),
+        author: typeof data.author_name === "string" && data.author_name.trim() ? data.author_name.trim() : null
+    };
 }
 
 /**

media-scrape/src/engine.ts

@@ -61,6 +61,10 @@ export interface PreviewBatchResult {
     skipped: number;
     failed: number;
     ratelimited: number;
+    /** Rows parked for one delayed retry (possible throttling, not confirmed gone). */
+    suspect: number;
+    /** Suspect rows whose delayed retry failed too. */
+    unverified: number;
     /** Rows still pending after the batch. */
     remaining: number;
     /** True when a stop request interrupted the batch. */
@@ -89,6 +93,13 @@ export interface ScrapeEngineOptions {
     rateLimitPauseMs?: number;
     /** Transient preview failures allowed before a row is marked permanently unreachable. Default 3. */
     previewMaxAttempts?: number;
+    /** Fresh URL for a row whose stored URL expired (message re-fetch). Best effort. */
+    refreshUrl?: (
+        scrapeId: string,
+        media: { id: number; url: string; playUrl: string | null }
+    ) => Promise<string | null>;
+    /** Delay before the single suspect retry. Default 50 s. */
+    suspectRetryMs?: number;
     /** Read dimensions and duration from a downloaded file. Defaults to ffprobe. */
     probe?: (
         path: string
@@ -113,6 +124,10 @@ function oldestId(messages: CoreMessage[]): string | null {
     return oldest;
 }
 
+function isDiscordHost(url: string): boolean {
+    return /^https?:\/\/[^/]*discordapp\.(com|net)\//i.test(url);
+}
+
 function isRateLimited(error: unknown): boolean {
     const anyError = error as { status?: number; message?: string } | undefined;
     return anyError?.status === 429 || /\b429\b|rate.?limit/i.test(String(anyError?.message ?? error));
@@ -557,7 +572,7 @@ export class ScrapeEngine {
         const dir = join(this.options.rootDir, scrapeId);
         const meta = this.active.get(scrapeId) ?? readScrapeMeta(dir);
         if (!meta) {
-            return { cached: 0, skipped: 0, failed: 0, ratelimited: 0, remaining: 0, stopped: false };
+            return { cached: 0, skipped: 0, failed: 0, ratelimited: 0, suspect: 0, unverified: 0, remaining: 0, stopped: false };
         }
 
         const releaseTraffic = await this.acquireTraffic();
@@ -590,9 +605,9 @@ export class ScrapeEngine {
                     break;
                 }
 
-                const title = await resolveEmbedTitle(row.url, options);
+                const resolved = await resolveEmbedTitle(row.url, options);
-                if (title) {
+                if (resolved) {
-                    store.markTitle(row.id, title);
+                    store.markTitle(row.id, resolved.title, resolved.author);
                     result.titled++;
                     continue;
                 }
@@ -620,24 +635,47 @@ export class ScrapeEngine {
         return result;
     }
 
+    /** Retry the due suspect rows (one delayed attempt each) for one scrape. */
+    async previewSuspects(scrapeId: string, limit: number): Promise<PreviewBatchResult> {
+        const dir = join(this.options.rootDir, scrapeId);
+        const meta = this.active.get(scrapeId) ?? readScrapeMeta(dir);
+        if (!meta) {
+            return { cached: 0, skipped: 0, failed: 0, ratelimited: 0, suspect: 0, unverified: 0, remaining: 0, stopped: false };
+        }
+
+        const releaseTraffic = await this.acquireTraffic();
+        const store = new ScrapeStore(dir);
+        try {
+            return await this.previewRows(store, dir, meta, Math.max(1, limit), this.previewOptions(meta), true);
+        } finally {
+            store.close();
+            releaseTraffic();
+        }
+    }
+
     /** One batch of preview rows. Mutates the store and the meta counters. */
     private async previewRows(
         store: ScrapeStore,
         dir: string,
         meta: ScrapeMeta,
         limit: number,
-        options: DownloadOptions & { embedPreviews: boolean; destinationDir: string | null }
+        options: DownloadOptions & { embedPreviews: boolean; destinationDir: string | null },
+        retryingSuspects = false
     ): Promise<PreviewBatchResult> {
         const result: PreviewBatchResult = {
             cached: 0,
             skipped: 0,
             failed: 0,
             ratelimited: 0,
+            suspect: 0,
+            unverified: 0,
             remaining: 0,
             stopped: false
         };
 
-        const pending = store.pendingPreviews(limit, true);
+        const pending = retryingSuspects
+            ? store.dueSuspects(limit, this.now())
+            : store.pendingPreviews(limit, true);
 
         for (const row of pending) {
             if (this.stopRequested.has(meta.id)) {
@@ -704,6 +742,7 @@ export class ScrapeEngine {
                 }
 
                 store.markPreview(row.id, { hash, bytes, ext, animHash });
+                store.clearSuspect(row.id);
                 meta.previewed = (meta.previewed ?? 0) + 1;
                 result.cached++;
 
@@ -723,6 +762,7 @@ export class ScrapeEngine {
                 const frame = await remoteFrame(previewRow.preview_url ?? previewRow.url, join(dir, "thumbs"));
                 if (frame) {
                     store.markPreview(row.id, { hash: frame.hash, bytes: frame.bytes, ext: "webp" });
+                    store.clearSuspect(row.id);
                     meta.previewed = (meta.previewed ?? 0) + 1;
                     result.cached++;
                 } else {
@@ -760,12 +800,58 @@ export class ScrapeEngine {
                     );
                 }
             } else {
-                store.markPreviewError(row.id, outcome.error ?? outcome.state);
+                const error = outcome.error ?? outcome.state;
-                result.skipped++;
+                const httpError = /^http \d/.test(error);
-                this.log(
+
-                    `${meta.id}: preview #${row.id} ${row.kind}/${row.provider ?? "?"} skipped: ` +
+                if (httpError && !retryingSuspects && this.options.refreshUrl && isDiscordHost(row.url)) {
-                        `${outcome.error ?? outcome.state} (${row.url.slice(0, 60)})`
+                    // The signed CDN URL may have expired. Refresh it from the source message,
-                );
+                    // persist the fresh one, and try once more before calling it gone.
+                    const refreshed = await this.options.refreshUrl(meta.id, {
+                        id: row.id,
+                        url: row.url,
+                        playUrl: row.play_url
+                    });
+                    if (refreshed && refreshed !== previewRow.url) {
+                        const retry = await downloadPreview({ ...previewRow, url: refreshed }, join(dir, "thumbs"), options);
+                        if (retry.state === "downloaded" && retry.hash) {
+                            store.markPreview(row.id, {
+                                hash: retry.hash,
+                                bytes: retry.bytes ?? 0,
+                                ext: retry.ext ?? "webp"
+                            });
+                            store.clearSuspect(row.id);
+                            meta.previewed = (meta.previewed ?? 0) + 1;
+                            result.cached++;
+                            this.persist(dir, meta);
+                            await this.sleep(previewGapMs(options));
+                            continue;
+                        }
+                    }
+                }
+
+                if (httpError) {
+                    if (retryingSuspects || row.preview_suspect) {
+                        store.confirmSuspect(row.id, `still ${error} after retry`);
+                        result.unverified++;
+                        this.log(
+                            `${meta.id}: preview #${row.id} still ${error} after retry, left unverified (${row.url.slice(0, 60)})`
+                        );
+                    } else {
+                        const retryAt = this.now() + (this.options.suspectRetryMs ?? 50_000);
+                        store.markSuspect(row.id, error, retryAt);
+                        result.suspect++;
+                        this.log(
+                            `${meta.id}: preview #${row.id} suspect (${error}), retrying after a pause (${row.url.slice(0, 60)})`
+                        );
+                    }
+                } else {
+                    store.markPreviewError(row.id, error);
+                    result.skipped++;
+                    this.log(
+                        `${meta.id}: preview #${row.id} ${row.kind}/${row.provider ?? "?"} skipped: ` +
+                            `${error} (${row.url.slice(0, 60)})`
+                    );
+                }
             }
 
             this.persist(dir, meta);

media-scrape/src/index.ts

@@ -5,6 +5,7 @@
 
 export { extractMedia, type ExtractedMedia } from "./extract.js";
 export { betterCandidate, candidateScore, sortCandidates, type DedupeCandidate } from "./dedupe.js";
+export { messageUrlFor } from "./discord-links.js";
 export { ogImageFromHtml, resolveEmbedPreview, resolveEmbedTitle } from "./embed-preview.js";
 export { isNearLimit, planRetention, type RetentionPlan, type RetentionScrape } from "./retention.js";
 export { isoFromSnowflake, snowflakeFromIso } from "./snowflake.js";

media-scrape/src/store.ts

@@ -169,10 +169,18 @@ export interface MediaRow {
     download_error: string | null;
     preview_error: string | null;
     preview_attempts: number;
+    /** First message that carried this media; null on rows written before linking. */
+    message_id: string | null;
     /** Embed title from Discord (YouTube and friends). */
     title: string | null;
     title_attempts: number;
     title_error: string | null;
+    /** YouTube channel name from oEmbed, kept even if the video later disappears. */
+    title_author: string | null;
+    /** Last suspect (possibly throttled) preview failure; retried once, then left alone. */
+    preview_suspect: string | null;
+    /** Epoch ms when the suspect row may be retried. Null once confirmed unavailable. */
+    preview_retry_at: number | null;
     /** Lowercased, punctuation-collapsed title for token-prefix search. */
     title_key: string | null;
     created_at: string;
@@ -242,6 +250,9 @@ CREATE TABLE IF NOT EXISTS media (
     title_key TEXT,
     title_attempts INTEGER NOT NULL DEFAULT 0,
     title_error TEXT,
+    title_author TEXT,
+    preview_suspect TEXT,
+    preview_retry_at INTEGER,
     created_at TEXT NOT NULL
 );
 
@@ -295,6 +306,11 @@ export class ScrapeStore {
             this.db.exec("ALTER TABLE media ADD COLUMN title_attempts INTEGER NOT NULL DEFAULT 0");
             this.db.exec("ALTER TABLE media ADD COLUMN title_error TEXT");
         }
+        if (!names.has("title_author")) this.db.exec("ALTER TABLE media ADD COLUMN title_author TEXT");
+        if (!names.has("preview_suspect")) {
+            this.db.exec("ALTER TABLE media ADD COLUMN preview_suspect TEXT");
+            this.db.exec("ALTER TABLE media ADD COLUMN preview_retry_at INTEGER");
+        }
 
         this.migrateYouTubeShorts();
     }
@@ -499,6 +515,88 @@ export class ScrapeStore {
      * Rows that still need a cached preview. Attachment/sticker images and GIFs always;
      * embed thumbnails only when `includeEmbeds` is set (download mode).
      */
+    /**
+     * Rows whose preview failed in a way that may be throttling rather than a dead link. Each is
+     * retried once after a delay; confirmed rows stay here and are skipped by normal passes, so a
+     * finished backfill never churns over genuinely unavailable media.
+     */
+    dueSuspects(limit = 500, nowMs = Date.now()): MediaRow[] {
+        return this.db
+            .prepare(
+                `SELECT * FROM media
+                 WHERE preview_hash IS NULL AND preview_error IS NULL
+                   AND preview_suspect IS NOT NULL
+                   AND preview_retry_at IS NOT NULL
+                   AND preview_retry_at <= ?
+                 ORDER BY preview_retry_at LIMIT ?`
+            )
+            .all(nowMs, limit) as unknown as MediaRow[];
+    }
+
+    /** Suspect rows that still have a retry coming. */
+    suspectCount(): number {
+        const row = this.db
+            .prepare(
+                "SELECT COUNT(*) AS count FROM media WHERE preview_hash IS NULL AND preview_suspect IS NOT NULL AND preview_retry_at IS NOT NULL"
+            )
+            .get() as { count: number | null } | undefined;
+        return row?.count ?? 0;
+    }
+
+    /** Suspect rows whose single retry failed too; skipped by normal passes. */
+    unverifiedCount(): number {
+        const row = this.db
+            .prepare(
+                "SELECT COUNT(*) AS count FROM media WHERE preview_hash IS NULL AND preview_suspect IS NOT NULL AND preview_retry_at IS NULL"
+            )
+            .get() as { count: number | null } | undefined;
+        return row?.count ?? 0;
+    }
+
+    /** Schedule the single delayed retry for a suspect row. */
+    markSuspect(id: number, error: string, retryAtMs: number): void {
+        this.db
+            .prepare("UPDATE media SET preview_suspect = ?, preview_retry_at = ? WHERE id = ?")
+            .run(error.slice(0, 200), retryAtMs, id);
+    }
+
+    /** The delayed retry failed too: keep the note but stop retrying. */
+    confirmSuspect(id: number, error: string): void {
+        this.db
+            .prepare("UPDATE media SET preview_suspect = ?, preview_retry_at = NULL WHERE id = ?")
+            .run(error.slice(0, 200), id);
+    }
+
+    /** The retry succeeded or the preview arrived another way. */
+    clearSuspect(id: number): void {
+        this.db.prepare("UPDATE media SET preview_suspect = NULL, preview_retry_at = NULL WHERE id = ?").run(id);
+    }
+
+    /** Discord-CDN rows closed out with an HTTP error; the recovery task retries these. */
+    discordPreviewFailures(limit = 5000): MediaRow[] {
+        return this.db
+            .prepare(
+                `SELECT * FROM media
+                 WHERE preview_hash IS NULL AND preview_error IS NOT NULL
+                   AND lower(url) LIKE '%discordapp%'
+                 ORDER BY id LIMIT ?`
+            )
+            .all(limit) as unknown as MediaRow[];
+    }
+
+    clearPreviewError(id: number): void {
+        this.db.prepare("UPDATE media SET preview_error = NULL WHERE id = ?").run(id);
+    }
+
+    discordPreviewFailureCount(): number {
+        const row = this.db
+            .prepare(
+                "SELECT COUNT(*) AS count FROM media WHERE preview_hash IS NULL AND preview_error IS NOT NULL AND lower(url) LIKE '%discordapp%'"
+            )
+            .get() as { count: number | null } | undefined;
+        return row?.count ?? 0;
+    }
+
     pendingPreviews(limit = 5000, includeEmbeds = false): MediaRow[] {
         const local =
             "((source IS NULL OR source != 'embed') AND kind IN ('image', 'gif', 'video', 'audio'))";
@@ -508,7 +606,10 @@ export class ScrapeStore {
 
         return this.db
             .prepare(
-                `SELECT * FROM media WHERE ${condition} AND preview_hash IS NULL AND preview_error IS NULL ORDER BY id LIMIT ?`
+                `SELECT * FROM media
+                 WHERE ${condition} AND preview_hash IS NULL AND preview_error IS NULL
+                   AND preview_suspect IS NULL
+                 ORDER BY id LIMIT ?`
             )
             .all(limit) as unknown as MediaRow[];
     }
@@ -542,6 +643,10 @@ export class ScrapeStore {
         titled: number;
         /** Rows closed out without a title. */
         titleFailed: number;
+        /** Preview failures kept for one delayed retry. */
+        suspect: number;
+        /** Suspect rows whose retry failed too. */
+        unverified: number;
         byKind: Record<MediaKind, { total: number; pending: number; cached: number; failed: number }>;
     } {
         const empty = () => ({ total: 0, pending: 0, cached: 0, failed: 0 });
@@ -603,6 +708,8 @@ export class ScrapeStore {
             titlePending: titles?.pending ?? 0,
             titled: titles?.titled ?? 0,
             titleFailed: titles?.failed ?? 0,
+            suspect: this.suspectCount(),
+            unverified: this.unverifiedCount(),
             byKind
         };
     }
@@ -625,11 +732,13 @@ export class ScrapeStore {
             .all(limit) as unknown as MediaRow[];
     }
 
-    /** Store a resolved title and its search key. */
+    /** Store a resolved title, its search key, and the provider's channel name. */
-    markTitle(id: number, title: string): void {
+    markTitle(id: number, title: string, author?: string | null): void {
         this.db
-            .prepare("UPDATE media SET title = ?, title_key = ?, title_error = NULL WHERE id = ?")
+            .prepare(
-            .run(title.slice(0, 300), normalizeTitleKey(title), id);
+                "UPDATE media SET title = ?, title_key = ?, title_error = NULL, title_author = COALESCE(?, title_author) WHERE id = ?"
+            )
+            .run(title.slice(0, 300), normalizeTitleKey(title), author ?? null, id);
     }
 
     /** Count one transient title failure and return the new total. */
@@ -873,7 +982,11 @@ export class ScrapeStore {
         const { where, values } = this.mediaWhere(options);
 
         const rows = this.db
-            .prepare(`SELECT * FROM media ${where} ORDER BY id DESC LIMIT ? OFFSET ?`)
+            .prepare(
+                `SELECT media.*,
+                        (SELECT message_id FROM media_sources WHERE media_id = media.id LIMIT 1) AS message_id
+                 FROM media ${where} ORDER BY id DESC LIMIT ? OFFSET ?`
+            )
             .all(...values, limit, offset);
 
         return rows as unknown as MediaRow[];

media-scrape/test/run.ts

@@ -24,6 +24,7 @@ import { BackfillQueue } from "../src/backfill.js";
 import { TitleLane } from "../src/titles.js";
 import { extractMedia, normalizeYouTubeUrl } from "../src/extract.js";
 import { PuppetBackend } from "../src/puppet-backend.js";
+import { messageUrlFor } from "../src/discord-links.js";
 import { betterCandidate, sortCandidates } from "../src/dedupe.js";
 import { aspectCondition, PROVIDER_FILTERS, resolutionCondition } from "../src/filter-presets.js";
 import { isNearLimit, planRetention } from "../src/retention.js";
@@ -1436,6 +1437,116 @@ void (async () => {
         reopened.close();
     });
 
+    await test("message links build for guilds and DMs", () => {
+        assert.equal(messageUrlFor("123", "456", "789"), "https://discord.com/channels/123/456/789");
+        assert.equal(messageUrlFor(null, "456", "789"), "https://discord.com/channels/@me/456/789");
+        assert.equal(messageUrlFor("123", "456", null), null);
+    });
+
+    await test("suspect rows park, due, and confirm", () => {
+        const dir = join(root, "suspects");
+        mkdirSync(dir, { recursive: true });
+        const store = new ScrapeStore(dir);
+        store.insertPage([
+            message("1700", {
+                attachments: [attachment({ filename: "gone.mp4", contentType: "video/mp4" })]
+            })
+        ]);
+
+        const row = store.queryMedia({ kind: "video" })[0];
+        const now = Date.now();
+        store.markSuspect(row.id, "http 404", now + 10_000);
+
+        assert.equal(store.previewCounts().suspect, 1);
+        assert.equal(store.previewCounts().unverified, 0);
+        assert.equal(store.pendingPreviews(10, true).length, 0);
+        assert.equal(store.dueSuspects(10, now).length, 0);
+        assert.equal(store.dueSuspects(10, now + 20_000).length, 1);
+
+        store.confirmSuspect(row.id, "still http 404 after retry");
+        assert.equal(store.previewCounts().suspect, 0);
+        assert.equal(store.previewCounts().unverified, 1);
+        assert.equal(store.dueSuspects(10, now + 20_000).length, 0);
+
+        store.markSuspect(row.id, "http 503", now);
+        assert.equal(store.previewCounts().suspect, 1);
+        assert.equal(store.previewCounts().unverified, 0);
+        assert.equal(store.dueSuspects(10, now).length, 1);
+        store.close();
+    });
+
+    await test("discord 404s become suspects and the delayed retry resolves them", async () => {
+        let failing = true;
+        const backend = new FakeBackend([
+            {
+                messages: [
+                    message("1701", {
+                        attachments: [attachment({ filename: "clip.mp4", contentType: "video/mp4" })]
+                    })
+                ]
+            }
+        ]);
+        const engine = engineFor(root, backend, {
+            suspectRetryMs: 0,
+            download: {
+                fetchImpl: async () =>
+                    failing
+                        ? new Response("gone", { status: 404 })
+                        : new Response("png", { status: 200, headers: { "content-type": "image/png" } }),
+                minGapMs: 0,
+                maxGapMs: 0,
+                sleep: async () => {}
+            }
+        });
+
+        const started = await engine.start({ channelId: "138", guildId: null, mode: "links", backend });
+        await engine.processQueue();
+
+        const first = await engine.previewBatch(started.id, 5);
+        assert.equal(first.suspect, 1);
+        assert.equal(first.skipped, 0);
+
+        // Normal passes leave suspects alone.
+        assert.equal((await engine.previewBatch(started.id, 5)).suspect, 0);
+
+        failing = false;
+        const retry = await engine.previewSuspects(started.id, 5);
+        assert.equal(retry.cached, 1);
+
+        const store = new ScrapeStore(join(root, started.id));
+        assert.equal(store.previewCounts().cached, 1);
+        assert.equal(store.previewCounts().suspect, 0);
+        store.close();
+
+        // A retry that fails again is confirmed unverified.
+        const dead = new FakeBackend([
+            {
+                messages: [
+                    message("1702", {
+                        attachments: [attachment({ filename: "dead.mp4", contentType: "video/mp4" })]
+                    })
+                ]
+            }
+        ]);
+        const deadEngine = engineFor(root, dead, {
+            suspectRetryMs: 0,
+            download: {
+                fetchImpl: async () => new Response("gone", { status: 404 }),
+                minGapMs: 0,
+                maxGapMs: 0,
+                sleep: async () => {}
+            }
+        });
+        const deadScrape = await deadEngine.start({ channelId: "139", guildId: null, mode: "links", backend: dead });
+        await deadEngine.processQueue();
+        assert.equal((await deadEngine.previewBatch(deadScrape.id, 5)).suspect, 1);
+        assert.equal((await deadEngine.previewSuspects(deadScrape.id, 5)).unverified, 1);
+        const deadStore = new ScrapeStore(join(root, deadScrape.id));
+        assert.equal(deadStore.previewCounts().unverified, 1);
+        assert.equal(deadStore.pendingPreviews(10, true).length, 0);
+        deadStore.close();
+    });
+
     await test("pendingTitles selects YouTube rows without a title", () => {
         const dir = join(root, "pending-titles");
         mkdirSync(dir, { recursive: true });

poc/public/media.css

@@ -802,3 +802,40 @@
     flex-direction: column;
     gap: 4px;
 }
+
+.vk-bot-progress {
+    display: flex;
+}
+
+.vk-bot-progress-cached {
+    background: var(--color-accent-400, #4f8cff);
+}
+
+.vk-bot-progress-pending {
+    background: var(--color-neutral-700);
+}
+
+.vk-bot-progress-failed {
+    background: #c04040;
+}
+
+.vk-bot-history {
+    margin-top: 8px;
+}
+
+.vk-bot-history-title {
+    font: 600 11px/1.6 ui-monospace, Menlo, monospace;
+    color: var(--color-neutral-300);
+    margin-bottom: 2px;
+}
+
+.vk-bot-history-entry {
+    font: 400 10px/1.5 ui-monospace, Menlo, monospace;
+    color: var(--color-neutral-500);
+}
+
+.vk-bot-hint {
+    margin-top: 8px;
+    font: 400 10px/1.5 ui-monospace, Menlo, monospace;
+    color: var(--color-neutral-500);
+}

poc/public/media.js

@@ -41,6 +41,7 @@
         pageSize: 60,
         backfill: null,
         titles: null,
+        recover: null,
         preferences: null,
         /** Scrapes that finished while this page was open, until the tab is reloaded. */
         completed: new Set()
@@ -77,7 +78,16 @@
                     </div>
                     <div id="backfill-summary" class="vk-bot-summary"></div>
                     <div id="title-lane" class="vk-bot-lane"></div>
+                    <div id="recover-lane" class="vk-bot-lane"></div>
                     <div id="backfill-jobs" class="vk-bot-jobs"></div>
+                    <div id="task-history" class="vk-bot-history"></div>
+                    <div class="vk-bot-hint">
+                        Failure policy: a failed preview gets one delayed retry (about 50 s). If a
+                        batch is two-thirds suspect failures, the cooldown doubles (60 s floor) and
+                        the retries run before the next batch. Rows that still fail are left
+                        unverified and skipped by later passes; the recovery task above retries
+                        Discord-CDN ones on demand.
+                    </div>
                 </div>
 
                 <div class="vk-bot-section">
@@ -104,6 +114,8 @@
     const backfillSummary = overlay.querySelector("#backfill-summary");
     const backfillJobs = overlay.querySelector("#backfill-jobs");
     const titleLane = overlay.querySelector("#title-lane");
+    const recoverLane = overlay.querySelector("#recover-lane");
+    const taskHistory = overlay.querySelector("#task-history");
     const tunablesHost = overlay.querySelector("#bot-tunables");
     const botErrors = overlay.querySelector("#bot-errors");
 
@@ -793,15 +805,24 @@
                         "vk-bot-job-member",
                         `${member.scrapeId} \u00b7 ${member.state} \u00b7 ${member.mode} \u00b7 ` +
                             `${member.backend} \u00b7 ${member.pending} pending` +
+                            (member.suspect ? ` + ${member.suspect} suspect` : "") +
+                            (member.unverified ? ` + ${member.unverified} unverified` : "") +
                             (kinds ? ` (${kinds})` : "")
                     )
                 );
             }
 
+            const total = Math.max(1, job.total);
             const progress = el("div", "vk-bot-progress");
-            const fill = el("div", "vk-bot-progress-fill");
+            for (const [className, value] of [
-            fill.style.width = `${Math.min(100, Math.round((job.cached / Math.max(1, job.total)) * 100))}%`;
+                ["vk-bot-progress-cached", job.cached],
-            progress.append(fill);
+                ["vk-bot-progress-pending", job.pending + (job.suspect ?? 0)],
+                ["vk-bot-progress-failed", job.failed]
+            ]) {
+                const segment = el("div", className);
+                segment.style.width = `${Math.min(100, (value / total) * 100)}%`;
+                progress.append(segment);
+            }
             row.append(progress);
 
             const actions = el("div", "vk-bot-job-actions");
@@ -879,6 +900,76 @@
         renderTitleLane(state.titles);
     }
 
+    function renderRecover(status) {
+        if (!status) return;
+        recoverLane.replaceChildren();
+
+        const head = el("div", "vk-bot-job-head");
+        head.append(el("span", "vk-bot-job-title", "Recover Discord previews"));
+        head.append(el("span", `vk-bot-state vk-bot-state-${status.state}`, status.state));
+
+        const parts = [`${status.total} to retry`];
+        if (status.processed) parts.push(`${status.processed} processed`);
+        if (status.recovered) parts.push(`${status.recovered} recovered`);
+        if (status.gone) parts.push(`${status.gone} unavailable`);
+        if (status.currentScrapeId) parts.push(`on ${channelLabel(status.currentScrapeId)}`);
+        head.append(el("span", "vk-bot-job-meta", parts.join(" \u00b7 ")));
+        recoverLane.append(head);
+
+        const actions = el("div", "vk-bot-job-actions");
+        if (status.state === "running") {
+            actions.append(button("Pause", () => void recoverAction("pause")));
+        } else if (status.total > 0) {
+            actions.append(button("Start", () => void recoverAction("start")));
+        }
+        recoverLane.append(actions);
+        recoverLane.append(
+            el(
+                "div",
+                "vk-bot-job-member",
+                "Re-fetches previews for Discord CDN rows closed as gone, refreshing each signed " +
+                    "URL through the source message (bot or puppet). Runs once; the result lands in " +
+                    "the history below."
+            )
+        );
+
+        renderTaskHistory(status.history ?? []);
+    }
+
+    function renderTaskHistory(history) {
+        taskHistory.replaceChildren();
+        if (!history.length) return;
+
+        taskHistory.append(el("div", "vk-bot-history-title", "Task history"));
+        for (const entry of history) {
+            taskHistory.append(
+                el(
+                    "div",
+                    "vk-bot-history-entry",
+                    `${new Date(entry.at).toLocaleString()} \u00b7 ${entry.name} \u00b7 ${entry.detail}`
+                )
+            );
+        }
+    }
+
+    async function recoverAction(action) {
+        try {
+            state.recover = await window.VK.api.post(`/api/media/recover/${action}`, {});
+            renderRecover(state.recover);
+        } catch (error) {
+            setStatus(`recover ${action} failed: ${error.message}`);
+        }
+    }
+
+    async function refreshRecover() {
+        try {
+            state.recover = await window.VK.api.get("/api/media/recover");
+        } catch {
+            state.recover = null;
+        }
+        renderRecover(state.recover);
+    }
+
     async function refreshBackfill() {
         try {
             state.backfill = await window.VK.api.get("/api/media/backfill");
@@ -1043,7 +1134,10 @@
         ["date", "Date"],
         ["source", "Source"],
         ["resolution", "Resolution"],
-        ["length", "Length"]
+        ["length", "Length"],
+        ["channel", "Channel"],
+        ["scrape", "Scrape"],
+        ["title", "Title"]
     ];
 
     /** "mp4 video", "webp image", "YouTube video", ... */
@@ -1062,7 +1156,14 @@
             date: item.postedAt ? new Date(item.postedAt).toLocaleString() : "—",
             source: item.provider ?? "discord",
             resolution: item.width && item.height ? `${item.width}x${item.height}` : "—",
-            length: item.durationSecs ? `${item.durationSecs.toFixed(1)}s` : "—"
+            length: item.durationSecs ? `${item.durationSecs.toFixed(1)}s` : "—",
+            channel: channelLabel(item.channelId),
+            scrape: item.scrapeId,
+            title: item.title
+                ? item.titleAuthor
+                    ? `${item.title} — ${item.titleAuthor}`
+                    : item.title
+                : ""
         };
     }
 
@@ -1819,6 +1920,7 @@
             if (!state.preferences) void refreshPreferences();
             void refreshBackfill();
             void refreshTitles();
+            void refreshRecover();
             void loadScrapes().then(renderScrapes);
             void refreshErrors();
         } else {
@@ -1839,6 +1941,7 @@
         if (state.view === "bot") {
             void refreshBackfill();
             void refreshTitles();
+            void refreshRecover();
         }
     });
 
@@ -1872,6 +1975,7 @@
         if (state.view === "bot") {
             void refreshBackfill();
             void refreshTitles();
+            void refreshRecover();
         }
     }, 3000);
 
@@ -2290,6 +2394,22 @@
 
     // ---- Media viewer ----
 
+    /** The canonical watch URL for YouTube items, for the fallback button. */
+    function youtubeWatchUrl(item) {
+        try {
+            const url = new URL(item.url);
+            const host = url.hostname.replace(/^www\./, "");
+            if (host === "youtube.com" || host === "m.youtube.com") {
+                const id = url.searchParams.get("v") ?? /^\/shorts\/([A-Za-z0-9_-]+)/.exec(url.pathname)?.[1];
+                return id ? `https://www.youtube.com/watch?v=${id}` : null;
+            }
+            if (host === "youtu.be") return `https://www.youtube.com/watch${url.pathname}`;
+        } catch {
+            // not a URL
+        }
+        return null;
+    }
+
     function embedUrlFor(item) {
         if (item.source !== "embed") return null;
 
@@ -2396,26 +2516,38 @@
         meta.replaceChildren();
         const values = metaValues(item);
         for (const [key, label] of META_FIELDS) {
+            if (!values[key]) continue;
             const line = el("div", "vk-media-meta-line");
             line.append(el("span", "vk-media-meta-key", `${label}: `));
             line.append(el("span", null, values[key]));
             meta.append(line);
         }
 
-        const link = el("button", "vk-media-link", item.url);
+        // The permanent message link, not the expiring CDN URL.
+        const linkUrl = item.messageUrl ?? item.url;
+        const link = el("button", "vk-media-link", linkUrl);
         link.type = "button";
-        link.title = "Open the original link";
+        link.title = item.messageUrl ? "Open the message" : "Open the original link";
-        link.addEventListener("click", () => openLinkWarning(item.url));
+        link.addEventListener("click", () => openLinkWarning(linkUrl));
         meta.append(link);
 
-        // "View full" opens the embedded media (player, local file, or a refreshed stream).
+        // "View full" plays in a new tab: the stream endpoint for Discord media (always a fresh
+        // source), the provider player for embeddable items.
         const streamPath = `/api/media/${item.scrapeId}/${item.itemId}/stream`;
         const fullUrl =
-            embedUrlFor(item) ??
+            item.messageUrl && item.kind === "video"
-            item.localUrl ??
+                ? streamPath
-            (item.kind === "video" ? streamPath : item.playUrl ?? item.thumbUrl ?? streamPath);
+                : embedUrlFor(item) ??
+                  item.localUrl ??
+                  (item.kind === "video" ? streamPath : item.playUrl ?? item.thumbUrl ?? streamPath);
         meta.append(button("View full", () => window.open(fullUrl, "_blank", "noreferrer")));
 
+        // Embeds break for age-gated or embed-disabled videos: keep a direct provider link.
+        const watchUrl = youtubeWatchUrl(item);
+        if (watchUrl) {
+            meta.append(button("Open on YouTube", () => window.open(watchUrl, "_blank", "noreferrer")));
+        }
+
         viewerModal.hidden = false;
     }
 
@@ -2437,6 +2569,7 @@
             <div id="link-target" class="vk-media-status"></div>
             <div class="vk-media-status">This opens a new website in a new tab.</div>
             <div class="vk-media-toolbar">
+                <button id="link-copy" class="btn btn-secondary vk-small-btn" type="button">Copy link</button>
                 <button id="link-cancel" class="btn btn-secondary vk-small-btn" type="button">Cancel</button>
                 <button id="link-continue" class="btn btn-primary vk-small-btn" type="button">Continue</button>
             </div>
@@ -2448,12 +2581,29 @@
 
     function openLinkWarning(url) {
         pendingLink = url;
+        linkModal.querySelector("#link-copy").textContent = "Copy link";
         linkModal.querySelector("#link-target").textContent = url;
         linkModal.hidden = false;
     }
 
+    linkModal.querySelector("#link-copy").addEventListener("click", async () => {
+        if (!pendingLink) return;
+        try {
+            await navigator.clipboard.writeText(pendingLink);
+        } catch {
+            const area = document.createElement("textarea");
+            area.value = pendingLink;
+            document.body.append(area);
+            area.select();
+            document.execCommand("copy");
+            area.remove();
+        }
+        linkModal.querySelector("#link-copy").textContent = "Copied";
+    });
+
     linkModal.querySelector("#link-cancel").addEventListener("click", () => {
         linkModal.hidden = true;
+        linkModal.querySelector("#link-copy").textContent = "Copy link";
     });
     linkModal.querySelector("#link-continue").addEventListener("click", () => {
         if (pendingLink) window.open(pendingLink, "_blank", "noreferrer");

poc/src/media.ts

@@ -10,6 +10,7 @@ import { isAbsolute, join } from "node:path";
 import {
     BackfillQueue,
     betterCandidate,
+    messageUrlFor,
     sortCandidates,
     dirSizeBytes,
     isNearLimit,
@@ -115,6 +116,10 @@ export interface MediaItemResult {
     scrapeId: string;
     itemId: number;
     channelId: string;
+    guildId: string | null;
+    /** The message that carried the media; the permanent link target. */
+    messageId: string | null;
+    messageUrl: string | null;
     kind: MediaKind;
     source: string | null;
     authorId: string | null;
@@ -139,6 +144,8 @@ export interface MediaItemResult {
     downloaded: boolean;
     /** Embed title (YouTube and friends), when Discord provided one. */
     title: string | null;
+    /** YouTube channel name kept from oEmbed, even if the video later disappears. */
+    titleAuthor: string | null;
     createdAt: string;
 }
 
@@ -182,6 +189,19 @@ export class MediaService {
     /** The newest bot and scrape errors, capped. Surfaced in the Bot tab. */
     private readonly errors: MediaErrorEntry[] = [];
 
+    /** One-shot maintenance: re-fetch previews for Discord rows closed out with HTTP errors. */
+    private readonly recover = {
+        state: "idle" as "idle" | "running" | "paused" | "done",
+        processed: 0,
+        recovered: 0,
+        gone: 0,
+        startedAt: null as number | null,
+        finishedAt: null as number | null,
+        currentScrapeId: null as string | null
+    };
+    /** Finished maintenance tasks, newest first. */
+    private readonly taskHistory: Array<{ name: string; at: string; detail: string }> = [];
+
     constructor(private readonly deps: MediaServiceDeps) {
         const tunables = this.deps.getMediaPrefs().tunables;
 
@@ -195,6 +215,14 @@ export class MediaService {
             pageMaxMs: tunables.timers.pageMaxMs,
             maxRetries: tunables.scrape.maxRetries,
             previewMaxAttempts: tunables.backfill.maxAttempts,
+            suspectRetryMs: 50_000,
+            refreshUrl: async (scrapeId, media) => {
+                const meta = this.engine.get(scrapeId);
+                if (!meta) return null;
+                const item = this.getMediaItem(scrapeId, media.id);
+                if (!item) return null;
+                return this.refreshUrls(meta, item);
+            },
             download: {
                 maxFileBytes: tunables.scrape.maxFileBytes,
                 previewMaxBytes: tunables.backfill.maxBytes,
@@ -293,6 +321,145 @@ export class MediaService {
         return this.titles.status();
     }
 
+    /** The recovery task with its live remaining count and the task history. */
+    recoverStatus(): {
+        state: string;
+        total: number;
+        processed: number;
+        recovered: number;
+        gone: number;
+        startedAt: string | null;
+        finishedAt: string | null;
+        currentScrapeId: string | null;
+        history: Array<{ name: string; at: string; detail: string }>;
+    } {
+        let total = 0;
+        for (const meta of this.engine.list()) {
+            if (meta.state === "deleted" || meta.state === "deleting") continue;
+            try {
+                const store = new ScrapeStore(scrapeDir(this.rootDir, meta.id));
+                try {
+                    total += store.discordPreviewFailureCount();
+                } finally {
+                    store.close();
+                }
+            } catch {
+                // an unreadable index has nothing to recover
+            }
+        }
+
+        return {
+            state: this.recover.state,
+            total,
+            processed: this.recover.processed,
+            recovered: this.recover.recovered,
+            gone: this.recover.gone,
+            startedAt: this.recover.startedAt ? new Date(this.recover.startedAt).toISOString() : null,
+            finishedAt: this.recover.finishedAt ? new Date(this.recover.finishedAt).toISOString() : null,
+            currentScrapeId: this.recover.currentScrapeId,
+            history: [...this.taskHistory]
+        };
+    }
+
+    startRecover(): void {
+        if (this.recover.state === "running") return;
+        this.recover.state = "running";
+        this.recover.startedAt = this.recover.startedAt ?? Date.now();
+        this.recover.processed = 0;
+        this.recover.recovered = 0;
+        this.recover.gone = 0;
+        this.deps.log?.("recover: retrying Discord-CDN previews marked gone");
+        void this.runRecover();
+    }
+
+    pauseRecover(): void {
+        if (this.recover.state !== "running") return;
+        this.recover.state = "paused";
+        this.deps.log?.("recover: pausing");
+    }
+
+    /**
+     * Walk every scrape's Discord-CDN preview failures, refresh the signed URL from the source
+     * message (slopbot REST for guild scrapes, the puppet for DMs and group chats), then let the
+     * engine fetch the preview. Rows whose URL cannot be refreshed are counted as gone.
+     */
+    private async runRecover(): Promise<void> {
+        const scrapeIds = this.engine
+            .list()
+            .filter(meta => meta.state !== "deleted" && meta.state !== "deleting")
+            .map(meta => meta.id);
+
+        while (this.recover.state === "running") {
+            let acted = false;
+
+            for (const scrapeId of scrapeIds) {
+                if (this.recover.state !== "running") break;
+
+                const meta = this.engine.get(scrapeId);
+                if (!meta) continue;
+
+                let store: ScrapeStore | null = null;
+                try {
+                    store = new ScrapeStore(scrapeDir(this.rootDir, scrapeId));
+                } catch {
+                    continue;
+                }
+
+                try {
+                    const rows = store.discordPreviewFailures(10);
+                    if (!rows.length) continue;
+
+                    acted = true;
+                    this.recover.currentScrapeId = scrapeId;
+                    const cleared: MediaRow[] = [];
+
+                    for (const row of rows) {
+                        if (this.recover.state !== "running") break;
+                        const fresh = await this.refreshUrls(meta, {
+                            ...row,
+                            scrapeId,
+                            channelId: meta.channelId
+                        } as MediaRow & { scrapeId: string; channelId: string });
+                        if (fresh) {
+                            store.clearPreviewError(row.id);
+                            cleared.push(row);
+                        } else {
+                            this.recover.gone++;
+                        }
+                        this.recover.processed++;
+                    }
+
+                    if (cleared.length && this.recover.state === "running") {
+                        await this.engine.previewBatch(scrapeId, cleared.length);
+                        for (const row of cleared) {
+                            if (store.getMedia(row.id)?.preview_hash) this.recover.recovered++;
+                            else this.recover.gone++;
+                        }
+                    }
+                } finally {
+                    store?.close();
+                }
+
+                if (acted) break;
+            }
+
+            if (!acted) break;
+        }
+
+        if (this.recover.state === "running") this.recover.state = "done";
+        this.recover.finishedAt = Date.now();
+        this.recover.currentScrapeId = null;
+        this.taskHistory.unshift({
+            name: "Recover Discord previews",
+            at: new Date().toISOString(),
+            detail: `${this.recover.recovered} recovered, ${this.recover.gone} unavailable`
+        });
+        if (this.taskHistory.length > 10) this.taskHistory.length = 10;
+        this.deps.log?.(
+            `recover: done, ${this.recover.recovered} recovered, ${this.recover.gone} unavailable`
+        );
+    }
+
     startBackfill(chatId?: string): BackfillStatus {
         this.backfill.start(chatId);
         return this.backfillStatus();
@@ -1006,6 +1173,9 @@ export class MediaService {
                 scrapeId: meta.id,
                 itemId: row.id,
                 channelId: meta.channelId,
+                guildId: meta.guildId,
+                messageId: row.message_id,
+                messageUrl: messageUrlFor(meta.guildId, meta.channelId, row.message_id),
                 kind: row.kind,
                 source: row.source,
                 authorId: row.author_id,
@@ -1029,6 +1199,7 @@ export class MediaService {
                 provider: row.provider,
                 downloaded: row.downloaded === 1,
                 title: row.title,
+                titleAuthor: row.title_author,
                 createdAt: row.created_at
             }));
     }

poc/src/webui.ts

@@ -842,6 +842,29 @@ export function startWebUi(deps: WebUiDeps): WebUiHandle {
         })
     );
 
+    app.get(
+        "/api/media/recover",
+        wrap(async (_req, res) => {
+            res.json({ ok: true, result: deps.media.recoverStatus() });
+        })
+    );
+
+    app.post(
+        "/api/media/recover/start",
+        wrap(async (_req, res) => {
+            deps.media.startRecover();
+            res.json({ ok: true, result: deps.media.recoverStatus() });
+        })
+    );
+
+    app.post(
+        "/api/media/recover/pause",
+        wrap(async (_req, res) => {
+            deps.media.pauseRecover();
+            res.json({ ok: true, result: deps.media.recoverStatus() });
+        })
+    );
+
     app.post(
         "/api/media/titles/start",
         wrap(async (_req, res) => {

poc/test/media-ui-smoke.mjs

@@ -206,6 +206,17 @@ try {
         () => document.querySelector("#title-lane")?.textContent?.includes("Titles (YouTube)"),
         { timeout: 15000 }
     );
+    check(
+        "recovery card renders",
+        (await page.locator("#recover-lane").textContent())?.includes("Recover Discord previews") === true
+    );
+    const withMessage = await page.evaluate(async () => {
+        const response = await fetch("/api/media?kind=video&limit=5");
+        const body = await response.json();
+        return (body.result ?? []).filter(item => item.messageUrl).length;
+    });
+    step("items with a message link", withMessage);
+    check("message links present", withMessage > 0, withMessage);
     check("title lane card renders", (await page.locator("#title-lane .vk-bot-job-head").count()) === 1);
 
     const summaryLines = await page.locator(".vk-bot-summary-line").count();