max / makenotwork

mt: paginate and flatten list_tracked_threads (F4) A user tracking hundreds of threads rendered an unbounded page, each row driving a double-nested unread-count subquery (a nested SELECT created_at FROM posts for the last-read cutoff plus an EXISTS mention check). The unread count also omitted removed_at IS NULL, so it counted mod-removed posts and couldn't use the m024 partial index. Add LIMIT/OFFSET pagination (count_tracked_threads + 50/page), resolve the last-read cutoff with a single LEFT JOIN instead of a per-row subquery, and filter removed posts out of the unread count. Ultra-fuzz Run #2 finding F4. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Max Johnson <me@maxj.phd> · 2026-06-18 20:09 UTC

Commit: 77e847105d67b10691f5ceeaf5a63e9aeb2ff795

Parent: f8cd220

5 files changed, +53 insertions, -10 deletions

M multithreaded/crates/mt-db/src/queries.rs +33 -5

			@@ -1163,11 +1163,19 @@ pub struct TrackedThreadRow {
1163	1163		pub tracked_at: DateTime<Utc>,
1164	1164		}
1165	1165
1166		-	/// List a user's tracked threads with unread post counts.
	1166	+	/// List a user's tracked threads with unread post counts, newest activity first.
	1167	+	///
	1168	+	/// Paginated (`limit`/`offset`) so a user tracking hundreds of threads doesn't
	1169	+	/// render — and recompute — an unbounded page. The last-read cutoff is resolved
	1170	+	/// with a single LEFT JOIN rather than a per-row nested subquery, and the unread
	1171	+	/// count excludes mod-removed posts (`p.removed_at IS NULL`) so the badge can't
	1172	+	/// be inflated by removed content and can use the `idx_posts_not_removed` index.
1167	1173		#[tracing::instrument(skip_all)]
1168	1174		pub async fn list_tracked_threads(
1169	1175		pool: &PgPool,
1170	1176		user_id: Uuid,
	1177	+	limit: i64,
	1178	+	offset: i64,
1171	1179		) -> Result<Vec<TrackedThreadRow>, sqlx::Error> {
1172	1180		sqlx::query_as::<_, TrackedThreadRow>(
1173	1181		"SELECT tt.thread_id,
			@@ -1177,9 +1185,8 @@ pub async fn list_tracked_threads(
1177	1185		cat.slug AS category_slug,
1178	1186		(SELECT COUNT(*) FROM posts p
1179	1187		WHERE p.thread_id = tt.thread_id
1180		-	AND (tt.last_read_post_id IS NULL OR p.created_at > (
1181		-	SELECT created_at FROM posts WHERE id = tt.last_read_post_id
1182		-	))
	1188	+	AND p.removed_at IS NULL
	1189	+	AND (lrp.created_at IS NULL OR p.created_at > lrp.created_at)
1183	1190		) AS unread_count,
1184	1191		EXISTS (
1185	1192		SELECT 1 FROM post_mentions pm
			@@ -1192,14 +1199,35 @@ pub async fn list_tracked_threads(
1192	1199		JOIN threads t ON t.id = tt.thread_id
1193	1200		JOIN categories cat ON cat.id = t.category_id
1194	1201		JOIN communities co ON co.id = cat.community_id
	1202	+	LEFT JOIN posts lrp ON lrp.id = tt.last_read_post_id
1195	1203		WHERE tt.user_id = $1 AND t.deleted_at IS NULL AND co.suspended_at IS NULL
1196		-	ORDER BY t.last_activity_at DESC",
	1204	+	ORDER BY t.last_activity_at DESC
	1205	+	LIMIT $2 OFFSET $3",
1197	1206		)
1198	1207		.bind(user_id)
	1208	+	.bind(limit)
	1209	+	.bind(offset)
1199	1210		.fetch_all(pool)
1200	1211		.await
1201	1212		}
1202	1213
	1214	+	/// Count a user's visible tracked threads (for pagination). Mirrors the
	1215	+	/// visibility filters of `list_tracked_threads`.
	1216	+	#[tracing::instrument(skip_all)]
	1217	+	pub async fn count_tracked_threads(pool: &PgPool, user_id: Uuid) -> Result<i64, sqlx::Error> {
	1218	+	sqlx::query_scalar(
	1219	+	"SELECT COUNT(*)
	1220	+	FROM tracked_threads tt
	1221	+	JOIN threads t ON t.id = tt.thread_id
	1222	+	JOIN categories cat ON cat.id = t.category_id
	1223	+	JOIN communities co ON co.id = cat.community_id
	1224	+	WHERE tt.user_id = $1 AND t.deleted_at IS NULL AND co.suspended_at IS NULL",
	1225	+	)
	1226	+	.bind(user_id)
	1227	+	.fetch_one(pool)
	1228	+	.await
	1229	+	}
	1230	+
1203	1231		// ============================================================================
1204	1232		// Tag queries
1205	1233		// ============================================================================

M multithreaded/src/routes/tracking.rs +16 -3

			@@ -1,7 +1,7 @@
1	1		//! Thread tracking handlers — track, untrack, tracked threads list.
2	2
3	3		use axum::{
4		-	extract::Path,
	4	+	extract::{Path, Query},
5	5		http::StatusCode,
6	6		response::{IntoResponse, Redirect, Response},
7	7		};
			@@ -102,18 +102,30 @@ pub(super) async fn tracking_info_page(
102	102		pub(super) async fn tracked_threads_page(
103	103		axum::extract::State(state): axum::extract::State<AppState>,
104	104		session: Session,
	105	+	Query(query): Query<super::ForumDirectoryQuery>,
105	106		MaybeUser(session_user): MaybeUser,
106	107		) -> Result<impl IntoResponse, Response> {
107	108		let csrf_token = Some(csrf::get_or_create_token(&session).await);
108	109		let user = session_user
109	110		.ok_or_else(\|\| Redirect::to("/auth/login").into_response())?;
110	111
111		-	let db_tracked = mt_db::queries::list_tracked_threads(&state.db, user.user_id)
	112	+	const PER_PAGE: i64 = 50;
	113	+	let total = mt_db::queries::count_tracked_threads(&state.db, user.user_id)
112	114		.await
113	115		.map_err(\|e\| {
114		-	tracing::error!(error = ?e, "db error listing tracked threads");
	116	+	tracing::error!(error = ?e, "db error counting tracked threads");
115	117		StatusCode::INTERNAL_SERVER_ERROR.into_response()
116	118		})?;
	119	+	let pagination = Pagination::new(query.page.unwrap_or(1).max(1), total, PER_PAGE);
	120	+	let offset = pagination.offset(PER_PAGE);
	121	+
	122	+	let db_tracked =
	123	+	mt_db::queries::list_tracked_threads(&state.db, user.user_id, PER_PAGE, offset)
	124	+	.await
	125	+	.map_err(\|e\| {
	126	+	tracing::error!(error = ?e, "db error listing tracked threads");
	127	+	StatusCode::INTERNAL_SERVER_ERROR.into_response()
	128	+	})?;
117	129
118	130		let threads = db_tracked
119	131		.into_iter()
			@@ -133,5 +145,6 @@ pub(super) async fn tracked_threads_page(
133	145		session_user: Some(template_user(&user, state.config.platform_admin_id)),
134	146		mnw_base_url: state.config.mnw_base_url.clone(),
135	147		threads,
	148	+	pagination,
136	149		})
137	150		}

M multithreaded/src/templates/public.rs +1

			@@ -478,6 +478,7 @@ pub struct TrackedThreadsTemplate {
478	478		pub session_user: Option<TemplateSessionUser>,
479	479		pub mnw_base_url: std::sync::Arc<str>,
480	480		pub threads: Vec<TrackedThreadViewRow>,
	481	+	pub pagination: Pagination,
481	482		}
482	483
483	484		// ============================================================================

M multithreaded/templates/pages/tracked.html +1

			@@ -59,6 +59,7 @@
59	59		{% endfor %}
60	60		</tbody>
61	61		</table>
	62	+	{% include "partials/pagination.html" %}
62	63		{% endif %}
63	64		</div>
64	65		{% endblock %}

M multithreaded/tests/workflows/tracking.rs +2 -2

			@@ -115,7 +115,7 @@ async fn unread_count_tracking() {
115	115		.unwrap();
116	116
117	117		// Check tracked threads — should show unread
118		-	let tracked = mt_db::queries::list_tracked_threads(&h.db, user_id).await.unwrap();
	118	+	let tracked = mt_db::queries::list_tracked_threads(&h.db, user_id, 50, 0).await.unwrap();
119	119		assert_eq!(tracked.len(), 1);
120	120		assert!(tracked[0].unread_count > 0, "Should have unread posts");
121	121		}
			@@ -138,7 +138,7 @@ async fn stop_tracking_all() {
138	138		let resp = h.client.post_form("/tracked/stop-all", "").await;
139	139		assert!(resp.status.is_redirection(), "Expected redirect, got {}", resp.status);
140	140
141		-	let tracked = mt_db::queries::list_tracked_threads(&h.db, user_id).await.unwrap();
	141	+	let tracked = mt_db::queries::list_tracked_threads(&h.db, user_id, 50, 0).await.unwrap();
142	142		assert_eq!(tracked.len(), 0, "All tracked threads should be removed");
143	143		}
144	144