v3: youtube embeds now honour the timestamp in the source url, with a migration backfilling existing dumps

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

api/db/migrate.ts

@@ -8,6 +8,7 @@ import { up as up0006Categories } from "./migrations/0006_categories.ts";
 import { up as up0007PasswordResetTokens } from "./migrations/0007_password_reset_tokens.ts";
 import { up as up0008ChatMessages } from "./migrations/0008_chat_messages.ts";
 import { up as up0009ChatReply } from "./migrations/0009_chat_reply.ts";
+import { up as up0010YoutubeEmbedStart } from "./migrations/0010_youtube_embed_start.ts";
 
 interface Migration {
   name: string;
@@ -27,6 +28,7 @@ const MIGRATIONS: Migration[] = [
   { name: "0007_password_reset_tokens", up: up0007PasswordResetTokens },
   { name: "0008_chat_messages", up: up0008ChatMessages },
   { name: "0009_chat_reply", up: up0009ChatReply },
+  { name: "0010_youtube_embed_start", up: up0010YoutubeEmbedStart },
 ];
 
 export function runMigrations(db: DatabaseSync): void {

api/db/migrations/0010_youtube_embed_start.ts

@@ -0,0 +1,76 @@
+import type { DatabaseSync } from "node:sqlite";
+
+// Backfills the `start` parameter on stored YouTube embed URLs.
+//
+// `rich_content.embedUrl` is computed once, at dump creation, and previously
+// dropped the timestamp carried by the source URL (`?t=1265`, `?t=1h2m3s`), so
+// those videos always opened at 0:00 in the global player. The provider now
+// translates `t`/`start` into the `start` param the iframe player honours; this
+// migration applies the same translation to rows written before that fix.
+//
+// Purely local — it re-derives the param from the already-stored source URL and
+// makes no network calls. Self-contained (no imports from api/services) so it
+// stays reproducible even if the provider's parsing evolves later.
+//
+// Idempotent: rows whose embed URL already carries a `start` are skipped, so a
+// fresh database built from schema.sql is simply a no-op.
+
+/** Parse `t`/`start` — plain seconds, `90s`, or `1h2m3s` / `20m5s`. */
+function extractStartSeconds(url: string): number | null {
+  let raw: string | null;
+  try {
+    const u = new URL(url);
+    raw = u.searchParams.get("t") ?? u.searchParams.get("start");
+  } catch {
+    return null;
+  }
+  if (!raw) return null;
+
+  if (/^\d+$/.test(raw)) return Number(raw);
+
+  const hms = /^(?:(\d+)h)?(?:(\d+)m)?(?:(\d+)s)?$/i.exec(raw);
+  if (!hms || (!hms[1] && !hms[2] && !hms[3])) return null;
+  return Number(hms[1] ?? 0) * 3600 + Number(hms[2] ?? 0) * 60 +
+    Number(hms[3] ?? 0);
+}
+
+export function up(db: DatabaseSync): void {
+  const rows = db.prepare(
+    `SELECT id, url, rich_content FROM dumps
+      WHERE kind = 'url' AND url IS NOT NULL AND rich_content IS NOT NULL;`,
+  ).all() as { id: string; url: string; rich_content: string }[];
+
+  const update = db.prepare(
+    `UPDATE dumps SET rich_content = ? WHERE id = ?;`,
+  );
+
+  let patched = 0;
+  for (const row of rows) {
+    let rich: { type?: string; embedUrl?: string };
+    try {
+      rich = JSON.parse(row.rich_content);
+    } catch {
+      continue; // malformed payload — leave it untouched
+    }
+    if (rich.type !== "youtube" || !rich.embedUrl) continue;
+
+    const start = extractStartSeconds(row.url);
+    if (!start) continue;
+
+    let embed: URL;
+    try {
+      embed = new URL(rich.embedUrl);
+    } catch {
+      continue;
+    }
+    if (embed.searchParams.has("start")) continue;
+
+    embed.searchParams.set("start", String(start));
+    update.run(JSON.stringify({ ...rich, embedUrl: embed.toString() }), row.id);
+    patched++;
+  }
+
+  if (patched > 0) {
+    console.log(`[migrate] 0010: added start offset to ${patched} embed(s)`);
+  }
+}

api/services/providers/youtube.ts

@@ -32,6 +32,30 @@ function extractPlaylistId(url: string): string | null {
   }
 }
 
+/**
+ * Extract the playback offset in seconds from a YouTube URL.
+ * Accepts `t` (plain seconds, `90s`, or `1h2m3s` / `20m5s` forms) and `start`
+ * (plain seconds). Returns null when absent or unparseable.
+ */
+function extractStartSeconds(url: string): number | null {
+  let raw: string | null;
+  try {
+    const u = new URL(url);
+    raw = u.searchParams.get("t") ?? u.searchParams.get("start");
+  } catch {
+    return null;
+  }
+  if (!raw) return null;
+
+  const plain = /^\d+$/.exec(raw);
+  if (plain) return Number(raw);
+
+  const hms = /^(?:(\d+)h)?(?:(\d+)m)?(?:(\d+)s)?$/i.exec(raw);
+  if (!hms || (!hms[1] && !hms[2] && !hms[3])) return null;
+  return Number(hms[1] ?? 0) * 3600 + Number(hms[2] ?? 0) * 60 +
+    Number(hms[3] ?? 0);
+}
+
 /** Matches /channel/UC…, /@handle, /c/name, /user/name */
 function extractChannelPath(url: string): string | null {
   try {
@@ -134,6 +158,8 @@ export const youtubeProvider: RichContentProvider = {
 
     const embedParams = new URLSearchParams({ rel: "0" });
     if (listId) embedParams.set("list", listId);
+    const start = extractStartSeconds(url);
+    if (start) embedParams.set("start", String(start));
 
     return {
       type: "youtube",