diff --git a/app/components/elements/Toast.tsx b/app/components/elements/Toast.tsx
index f2f34d135..b5b4d1422 100644
--- a/app/components/elements/Toast.tsx
+++ b/app/components/elements/Toast.tsx
@@ -19,7 +19,7 @@ interface QueuedToast {
 
 class ToastQueue {
 	private toasts: QueuedToast[] = [];
-	private listeners = new Set<() => void>();
+	private readonly listeners = new Set<() => void>();
 	private counter = 0;
 
 	add(content: SendouToast, options?: { timeout?: number }) {
diff --git a/app/features/build-analyzer/core/stats.ts b/app/features/build-analyzer/core/stats.ts
index 7e1dfed9c..89e4e4416 100644
--- a/app/features/build-analyzer/core/stats.ts
+++ b/app/features/build-analyzer/core/stats.ts
@@ -201,7 +201,7 @@ function specialPoint({
 
 	const { effect } = abilityPointsToEffects({
 		abilityPoints: apFromMap({
-			abilityPoints: abilityPoints,
+			abilityPoints,
 			ability: SPECIAL_POINT_ABILITY,
 		}),
 		key: "IncreaseRt_Special",
@@ -252,7 +252,7 @@ function specialLost(
 
 	const { baseEffect, effect } = abilityPointsToEffects({
 		abilityPoints: apFromMap({
-			abilityPoints: abilityPoints,
+			abilityPoints,
 			ability: SPECIAL_SAVED_AFTER_DEATH_ABILITY,
 		}),
 		key: "SpecialGaugeRt_Restart",
diff --git a/app/features/events/events-hooks.browser.test.tsx b/app/features/events/events-hooks.browser.test.tsx
index 5c183fcc5..a87535775 100644
--- a/app/features/events/events-hooks.browser.test.tsx
+++ b/app/features/events/events-hooks.browser.test.tsx
@@ -13,7 +13,10 @@ import type { ServerEvent } from "./events-types";
 class FakeEventSource {
 	static instances: FakeEventSource[] = [];
 
-	private listeners = new Map<string, Set<(event: MessageEvent) => void>>();
+	private readonly listeners = new Map<
+		string,
+		Set<(event: MessageEvent) => void>
+	>();
 
 	url: string;
 
diff --git a/app/features/map-list-generator/core/map-pool.ts b/app/features/map-list-generator/core/map-pool.ts
index 5eaa9f6b6..17bccf6fa 100644
--- a/app/features/map-list-generator/core/map-pool.ts
+++ b/app/features/map-list-generator/core/map-pool.ts
@@ -15,7 +15,7 @@ export type DbMapPoolList = Array<
 >;
 
 export class MapPool {
-	private source: string | ReadonlyMapPoolObject;
+	private readonly source: string | ReadonlyMapPoolObject;
 	private asSerialized?: string;
 	private asObject?: ReadonlyMapPoolObject;
 
diff --git a/app/features/map-planner/components/Planner.tsx b/app/features/map-planner/components/Planner.tsx
index 6e13729be..36391a743 100644
--- a/app/features/map-planner/components/Planner.tsx
+++ b/app/features/map-planner/components/Planner.tsx
@@ -287,11 +287,11 @@ export default function Planner() {
 				type: "image",
 				x: point[0],
 				y: point[1],
-				isLocked: isLocked,
+				isLocked,
 				id: shapeId,
 				meta: meta ?? {},
 				props: {
-					assetId: assetId,
+					assetId,
 					w: size[0],
 					h: size[1],
 				},
diff --git a/app/features/params/components/WeaponParamsTable.tsx b/app/features/params/components/WeaponParamsTable.tsx
index 2ba57c149..e1ab728c0 100644
--- a/app/features/params/components/WeaponParamsTable.tsx
+++ b/app/features/params/components/WeaponParamsTable.tsx
@@ -408,7 +408,7 @@ function DamageRateInfoSection({
 		damageMultipliers[String(weaponId)]?.find((m) => m.target === target);
 
 	return (
-		<Fragment>
+		<>
 			<tr>
 				<td
 					colSpan={visibleWeaponIds.length + 1}
@@ -467,7 +467,7 @@ function DamageRateInfoSection({
 					</tr>
 				);
 			})}
-		</Fragment>
+		</>
 	);
 }
 
diff --git a/app/features/scanner/core/detectors/scheduler.ts b/app/features/scanner/core/detectors/scheduler.ts
index ade301e51..51719035f 100644
--- a/app/features/scanner/core/detectors/scheduler.ts
+++ b/app/features/scanner/core/detectors/scheduler.ts
@@ -102,8 +102,8 @@ interface DetectorState {
 }
 
 export class DetectorScheduler {
-	#options: SchedulerOptions;
-	#states = new Map<string, DetectorState>();
+	readonly #options: SchedulerOptions;
+	readonly #states = new Map<string, DetectorState>();
 	#maxT = Number.NEGATIVE_INFINITY;
 	#lastActivityT = Number.NEGATIVE_INFINITY;
 	#matchOpenUntilT = Number.NEGATIVE_INFINITY;
diff --git a/app/features/scanner/core/timeline/index.ts b/app/features/scanner/core/timeline/index.ts
index bfd993e5e..2109a6750 100644
--- a/app/features/scanner/core/timeline/index.ts
+++ b/app/features/scanner/core/timeline/index.ts
@@ -77,8 +77,8 @@ export type TimelineAction =
 	| { action: "dropped"; reason: "low-confidence" };
 
 export class TimelineBuilder {
-	#events: DetectedEvent[] = [];
-	#options: TimelineOptions;
+	readonly #events: DetectedEvent[] = [];
+	readonly #options: TimelineOptions;
 
 	constructor(options: Partial<TimelineOptions> = {}) {
 		this.#options = { ...DEFAULT_TIMELINE_OPTIONS, ...options };
diff --git a/app/features/scanner/core/timeline/same-scoreboard.ts b/app/features/scanner/core/timeline/same-scoreboard.ts
index 7c13a38ca..90ff64c0b 100644
--- a/app/features/scanner/core/timeline/same-scoreboard.ts
+++ b/app/features/scanner/core/timeline/same-scoreboard.ts
@@ -81,10 +81,12 @@ export function sameScoreboardMatch(a: unknown, b: unknown): boolean {
 	// are distinctive per match — near-zero overlap means a different board
 	const pa = paints(da);
 	const pb = paints(db);
-	if (pa.length >= PAINT_MIN_READ && pb.length >= PAINT_MIN_READ) {
-		if (multisetOverlap(pa, pb) < Math.min(pa.length, pb.length) / 2)
-			return false;
-	}
+	if (
+		pa.length >= PAINT_MIN_READ &&
+		pb.length >= PAINT_MIN_READ &&
+		multisetOverlap(pa, pb) < Math.min(pa.length, pb.length) / 2
+	)
+		return false;
 
 	return true;
 }
diff --git a/app/features/scanner/worker/client.ts b/app/features/scanner/worker/client.ts
index 48eed2ddd..276561d1b 100644
--- a/app/features/scanner/worker/client.ts
+++ b/app/features/scanner/worker/client.ts
@@ -43,13 +43,13 @@ interface QueuedFrame {
 }
 
 export class AnalyzerClient {
-	#worker: Worker;
+	readonly #worker: Worker;
 	#ready = false;
 	#busy = false;
-	#onResult: ResultHandler;
-	#onError: ErrorHandler;
-	#onDone: DoneHandler | undefined;
-	#readyPromise: Promise<void>;
+	readonly #onResult: ResultHandler;
+	readonly #onError: ErrorHandler;
+	readonly #onDone: DoneHandler | undefined;
+	readonly #readyPromise: Promise<void>;
 	#rejectReady: ((error: Error) => void) | undefined;
 	#idleWaiters: (() => void)[] = [];
 	#chunk: PendingChunk | null = null;
diff --git a/app/features/sendouq-match/core/skills.server.ts b/app/features/sendouq-match/core/skills.server.ts
index 579da8abb..77147f1de 100644
--- a/app/features/sendouq-match/core/skills.server.ts
+++ b/app/features/sendouq-match/core/skills.server.ts
@@ -41,7 +41,7 @@ export async function calculateMatchSkills({
 
 		for (const [index, userId] of winner.entries()) {
 			newSkills.push({
-				groupMatchId: groupMatchId,
+				groupMatchId,
 				identifier: null,
 				mu: winnerTeamNew[index].mu,
 				season,
@@ -52,7 +52,7 @@ export async function calculateMatchSkills({
 
 		for (const [index, userId] of loser.entries()) {
 			newSkills.push({
-				groupMatchId: groupMatchId,
+				groupMatchId,
 				identifier: null,
 				mu: loserTeamNew[index].mu,
 				season,
@@ -75,7 +75,7 @@ export async function calculateMatchSkills({
 		);
 
 		newSkills.push({
-			groupMatchId: groupMatchId,
+			groupMatchId,
 			identifier: winnerTeamIdentifier,
 			mu: winnerGroupNew.mu,
 			season,
@@ -83,7 +83,7 @@ export async function calculateMatchSkills({
 			userId: null,
 		});
 		newSkills.push({
-			groupMatchId: groupMatchId,
+			groupMatchId,
 			identifier: loserTeamIdentifier,
 			mu: loserGroupNew.mu,
 			season,
diff --git a/app/features/sendouq-streams/core/streams.server.ts b/app/features/sendouq-streams/core/streams.server.ts
index 5ab3082fb..af1751a33 100644
--- a/app/features/sendouq-streams/core/streams.server.ts
+++ b/app/features/sendouq-streams/core/streams.server.ts
@@ -22,7 +22,7 @@ export function cachedStreams() {
 
 	return cachified({
 		key: SENDOUQ_STREAMS_KEY,
-		cache: cache,
+		cache,
 		ttl: ttl(IN_MILLISECONDS.HALF_HOUR),
 		async getFreshValue() {
 			return streamedMatches({
diff --git a/app/features/sendouq/core/SendouQ.server.ts b/app/features/sendouq/core/SendouQ.server.ts
index c7f662962..efd0560a2 100644
--- a/app/features/sendouq/core/SendouQ.server.ts
+++ b/app/features/sendouq/core/SendouQ.server.ts
@@ -57,10 +57,10 @@ const SECONDS_TILL_STALE =
 
 class SendouQClass {
 	groups;
-	#recentMatches;
-	#isAccurateTiers;
-	#userSkills;
-	#intervals;
+	readonly #recentMatches;
+	readonly #isAccurateTiers;
+	readonly #userSkills;
+	readonly #intervals;
 	usersInQueue;
 
 	constructor(
diff --git a/app/features/top-search/actions/xsearch.player.$id.server.ts b/app/features/top-search/actions/xsearch.player.$id.server.ts
index 542a6cf3c..a4a3eb495 100644
--- a/app/features/top-search/actions/xsearch.player.$id.server.ts
+++ b/app/features/top-search/actions/xsearch.player.$id.server.ts
@@ -30,7 +30,7 @@ export const action = async ({ params }: ActionFunctionArgs) => {
 	);
 
 	logger.info("Unlinking player", {
-		id: id,
+		id,
 		userId: user.id,
 	});
 
diff --git a/app/features/tournament-bracket/core/Bracket/SwissBracket.ts b/app/features/tournament-bracket/core/Bracket/SwissBracket.ts
index a9516270a..34c4715e9 100644
--- a/app/features/tournament-bracket/core/Bracket/SwissBracket.ts
+++ b/app/features/tournament-bracket/core/Bracket/SwissBracket.ts
@@ -274,7 +274,7 @@ export class SwissBracket extends Bracket {
 					teamId: winner.id,
 					setWins: 1,
 					setLosses: 0,
-					mapWins: mapWins,
+					mapWins,
 					mapLosses: 0,
 				});
 			}
diff --git a/app/features/tournament-bracket/core/Tournament.ts b/app/features/tournament-bracket/core/Tournament.ts
index 38db29ea2..75eb20731 100644
--- a/app/features/tournament-bracket/core/Tournament.ts
+++ b/app/features/tournament-bracket/core/Tournament.ts
@@ -114,13 +114,13 @@ export class Tournament {
 	ctx;
 	/** See {@link TournamentArgs.participatedUsers}, null when this view did not get them. */
 	readonly participatedUserIds: number[] | null;
-	private args;
-	private data;
-	private _brackets: Array<Bracket | undefined> = [];
+	private readonly args;
+	private readonly data;
+	private readonly _brackets: Array<Bracket | undefined> = [];
 	private _allBrackets: Bracket[] | undefined;
 	private _derivedMeta: BracketDerivedMeta[] | undefined;
 	private _bracketsMeta: BracketMeta[] | undefined;
-	private bracketIdxsBeingBuilt = new Set<number>();
+	private readonly bracketIdxsBeingBuilt = new Set<number>();
 
 	constructor(args: TournamentArgs) {
 		const { data, ctx, bracketsMeta, brackets } = args;
diff --git a/app/features/tournament-bracket/core/engine/create/builder.ts b/app/features/tournament-bracket/core/engine/create/builder.ts
index a36e6d13b..4e5dcf692 100644
--- a/app/features/tournament-bracket/core/engine/create/builder.ts
+++ b/app/features/tournament-bracket/core/engine/create/builder.ts
@@ -63,7 +63,7 @@ export class StageCreator {
 		slots: ParticipantSlot[],
 	): void {
 		const groupId = this.insertGroup({
-			stageId: stageId,
+			stageId,
 			number,
 		});
 
@@ -87,7 +87,7 @@ export class StageCreator {
 		slotsB: ParticipantSlot[],
 	): void {
 		const groupId = this.insertGroup({
-			stageId: stageId,
+			stageId,
 			number,
 		});
 
@@ -105,7 +105,7 @@ export class StageCreator {
 	): StandardBracketResults {
 		const roundCount = helpers.getUpperBracketRoundCount(slots.length);
 		const groupId = this.insertGroup({
-			stageId: stageId,
+			stageId,
 			number,
 		});
 
@@ -139,7 +139,7 @@ export class StageCreator {
 		const ordered = ordering[method](losers[losersId++]);
 
 		const groupId = this.insertGroup({
-			stageId: stageId,
+			stageId,
 			number,
 		});
 
@@ -179,7 +179,7 @@ export class StageCreator {
 		duels: Duel[],
 	): void {
 		const groupId = this.insertGroup({
-			stageId: stageId,
+			stageId,
 			number,
 		});
 
@@ -196,8 +196,8 @@ export class StageCreator {
 	): void {
 		const roundId = this.insertRound({
 			number: roundNumber,
-			stageId: stageId,
-			groupId: groupId,
+			stageId,
+			groupId,
 		});
 
 		for (let i = 0; i < matchCount; i++) {
@@ -225,9 +225,9 @@ export class StageCreator {
 
 		this.insertMatch({
 			number: matchNumber,
-			stageId: stageId,
-			groupId: groupId,
-			roundId: roundId,
+			stageId,
+			groupId,
+			roundId,
 			opponent1,
 			opponent2,
 			winnerSide: null,
@@ -235,11 +235,10 @@ export class StageCreator {
 	}
 
 	/** No ordering for major rounds (the first round must be ordered beforehand), LB minor rounds use the given method. */
-	getCurrentDuels(previousDuels: Duel[], currentDuelCount: number): Duel[];
 	getCurrentDuels(
 		previousDuels: Duel[],
 		currentDuelCount: number,
-		major: true,
+		major?: true,
 	): Duel[];
 	getCurrentDuels(
 		previousDuels: Duel[],
diff --git a/app/features/tournament-bracket/core/engine/create/helpers.test.ts b/app/features/tournament-bracket/core/engine/create/helpers.test.ts
index d47484e30..855913a27 100644
--- a/app/features/tournament-bracket/core/engine/create/helpers.test.ts
+++ b/app/features/tournament-bracket/core/engine/create/helpers.test.ts
@@ -339,9 +339,9 @@ function assertRoundRobin(input: number[], output: [number, number][][]): void {
 	const matchPerRound = Math.floor(n / 2);
 	const roundCount = n % 2 === 0 ? n - 1 : n;
 
-	if (output.length !== roundCount) throw Error("Round count is wrong");
+	if (output.length !== roundCount) throw new Error("Round count is wrong");
 	if (!output.every((round) => round.length === matchPerRound))
-		throw Error("Not every round has the good number of matches");
+		throw new Error("Not every round has the good number of matches");
 
 	const checkAllOpponents = Object.fromEntries(
 		input.map((element) => [element, new Set<number>()]),
@@ -351,22 +351,22 @@ function assertRoundRobin(input: number[], output: [number, number][][]): void {
 		const checkUnique = new Set<number>();
 
 		for (const match of round) {
-			if (match.length !== 2) throw Error("One match is not a pair");
+			if (match.length !== 2) throw new Error("One match is not a pair");
 
 			if (checkUnique.has(match[0]))
-				throw Error("This team is already playing");
+				throw new Error("This team is already playing");
 			checkUnique.add(match[0]);
 
 			if (checkUnique.has(match[1]))
-				throw Error("This team is already playing");
+				throw new Error("This team is already playing");
 			checkUnique.add(match[1]);
 
 			if (checkAllOpponents[match[0]].has(match[1]))
-				throw Error("The team has already matched this team");
+				throw new Error("The team has already matched this team");
 			checkAllOpponents[match[0]].add(match[1]);
 
 			if (checkAllOpponents[match[1]].has(match[0]))
-				throw Error("The team has already matched this team");
+				throw new Error("The team has already matched this team");
 			checkAllOpponents[match[1]].add(match[0]);
 		}
 	}
@@ -380,9 +380,9 @@ function assertAbDivisionRoundRobin(
 	const roundCount = Math.max(divisionA.length, divisionB.length);
 	const matchesPerRound = Math.min(divisionA.length, divisionB.length);
 
-	if (output.length !== roundCount) throw Error("Round count is wrong");
+	if (output.length !== roundCount) throw new Error("Round count is wrong");
 	if (!output.every((round) => round.length === matchesPerRound))
-		throw Error("Not every round has the good number of matches");
+		throw new Error("Not every round has the good number of matches");
 
 	const aSet = new Set(divisionA);
 	const bSet = new Set(divisionB);
@@ -392,26 +392,28 @@ function assertAbDivisionRoundRobin(
 		const playingInRound = new Set<number>();
 
 		for (const match of round) {
-			if (match.length !== 2) throw Error("One match is not a pair");
+			if (match.length !== 2) throw new Error("One match is not a pair");
 
 			const [a, b] = match;
 
-			if (!aSet.has(a)) throw Error(`${a} is not a division A participant`);
-			if (!bSet.has(b)) throw Error(`${b} is not a division B participant`);
+			if (!aSet.has(a)) throw new Error(`${a} is not a division A participant`);
+			if (!bSet.has(b)) throw new Error(`${b} is not a division B participant`);
 
-			if (playingInRound.has(a)) throw Error("This team is already playing");
+			if (playingInRound.has(a))
+				throw new Error("This team is already playing");
 			playingInRound.add(a);
 
-			if (playingInRound.has(b)) throw Error("This team is already playing");
+			if (playingInRound.has(b))
+				throw new Error("This team is already playing");
 			playingInRound.add(b);
 
 			const pairingKey = `${a}-${b}`;
 			if (seenPairings.has(pairingKey))
-				throw Error("The teams have already been paired");
+				throw new Error("The teams have already been paired");
 			seenPairings.add(pairingKey);
 		}
 	}
 
 	if (seenPairings.size !== divisionA.length * divisionB.length)
-		throw Error("Not every A vs B pairing was generated");
+		throw new Error("Not every A vs B pairing was generated");
 }
diff --git a/app/features/tournament-bracket/core/engine/create/helpers.ts b/app/features/tournament-bracket/core/engine/create/helpers.ts
index 1d9a2a7e6..536db7429 100644
--- a/app/features/tournament-bracket/core/engine/create/helpers.ts
+++ b/app/features/tournament-bracket/core/engine/create/helpers.ts
@@ -80,11 +80,12 @@ export function makeAbDivisionGroups<T>(
 	divisionB: T[],
 	groupCount: number,
 ): { a: T[]; b: T[] }[] {
-	if (groupCount <= 0) throw Error("Group count must be strictly positive.");
+	if (groupCount <= 0)
+		throw new Error("Group count must be strictly positive.");
 
 	if (divisionA.length !== divisionB.length) {
 		if (groupCount !== 1)
-			throw Error(
+			throw new Error(
 				"Uneven A/B divisions are only supported with a single group.",
 			);
 
@@ -92,7 +93,7 @@ export function makeAbDivisionGroups<T>(
 	}
 
 	if (divisionA.length % groupCount !== 0)
-		throw Error("Pool size must be divisible by group count.");
+		throw new Error("Pool size must be divisible by group count.");
 
 	const aOrdered = ordering["groups.seed_optimized"](divisionA, groupCount);
 	const bOrdered = ordering["groups.seed_optimized"](divisionB, groupCount);
@@ -152,14 +153,16 @@ export function ensureValidSize(
 	participantCount: number,
 ): void {
 	if (participantCount < 2)
-		throw Error("Impossible to create a stage with less than 2 participants.");
+		throw new Error(
+			"Impossible to create a stage with less than 2 participants.",
+		);
 
 	if (stageType === "round_robin") {
 		return;
 	}
 
 	if (!Number.isInteger(Math.log2(participantCount)))
-		throw Error(
+		throw new Error(
 			"The library only supports a participant count which is a power of two.",
 		);
 }
diff --git a/app/features/tournament-bracket/core/engine/create/index.ts b/app/features/tournament-bracket/core/engine/create/index.ts
index 69d4fc76a..bb8e56ed2 100644
--- a/app/features/tournament-bracket/core/engine/create/index.ts
+++ b/app/features/tournament-bracket/core/engine/create/index.ts
@@ -50,7 +50,7 @@ export function createResolved(input: ResolvedCreateBracketInput): BracketData {
 			createDoubleElimination(creator);
 			break;
 		default:
-			throw Error("Unknown stage type.");
+			throw new Error("Unknown stage type.");
 	}
 
 	return creator.data;
@@ -65,7 +65,8 @@ function attachRoundMaps(
 
 	const resolveRound = (roundId: number) => {
 		const round = roundsById.get(roundId);
-		if (!round) throw Error(`No round found for map list round id ${roundId}`);
+		if (!round)
+			throw new Error(`No round found for map list round id ${roundId}`);
 		return round;
 	};
 
@@ -75,7 +76,7 @@ function attachRoundMaps(
 			data.round.map((round) => round.number),
 		).size;
 		if (mapsInput.length !== distinctRoundNumberCount) {
-			throw Error("Invalid map list count");
+			throw new Error("Invalid map list count");
 		}
 
 		const mapsByRoundNumber = new Map(
@@ -87,7 +88,8 @@ function attachRoundMaps(
 
 		for (const round of data.round) {
 			const maps = mapsByRoundNumber.get(round.number);
-			if (!maps) throw Error(`No maps found for round number ${round.number}`);
+			if (!maps)
+				throw new Error(`No maps found for round number ${round.number}`);
 			round.maps = { ...maps };
 		}
 
@@ -95,7 +97,7 @@ function attachRoundMaps(
 	}
 
 	if (mapsInput.length !== data.round.length) {
-		throw Error("Invalid map list count");
+		throw new Error("Invalid map list count");
 	}
 
 	for (const input of mapsInput) {
@@ -103,7 +105,7 @@ function attachRoundMaps(
 	}
 
 	for (const round of data.round) {
-		if (!round.maps) throw Error(`Round id ${round.id} is missing maps`);
+		if (!round.maps) throw new Error(`Round id ${round.id} is missing maps`);
 	}
 }
 
diff --git a/app/features/tournament-bracket/core/engine/create/round-robin.ts b/app/features/tournament-bracket/core/engine/create/round-robin.ts
index 68c233bcd..8a9e689c5 100644
--- a/app/features/tournament-bracket/core/engine/create/round-robin.ts
+++ b/app/features/tournament-bracket/core/engine/create/round-robin.ts
@@ -37,10 +37,10 @@ function getRoundRobinGroups(creator: StageCreator): ParticipantSlot[][] {
 		creator.settings.groupCount === undefined ||
 		!Number.isInteger(creator.settings.groupCount)
 	)
-		throw Error("You must specify a group count for round-robin stages.");
+		throw new Error("You must specify a group count for round-robin stages.");
 
 	if (creator.settings.groupCount <= 0)
-		throw Error("You must provide a strictly positive group count.");
+		throw new Error("You must provide a strictly positive group count.");
 
 	const slots = creator.getSlots();
 	const ordered = ordering["groups.seed_optimized"](
@@ -59,19 +59,21 @@ function getAbDivisionGroups(creator: StageCreator): {
 		creator.settings.groupCount === undefined ||
 		!Number.isInteger(creator.settings.groupCount)
 	)
-		throw Error("You must specify a group count for round-robin stages.");
+		throw new Error("You must specify a group count for round-robin stages.");
 
 	if (creator.settings.groupCount <= 0)
-		throw Error("You must provide a strictly positive group count.");
+		throw new Error("You must provide a strictly positive group count.");
 
 	const abDivisions = creator.input.abDivisions;
 	if (!abDivisions)
-		throw Error("abDivisions must be provided when hasAbDivisions is enabled.");
+		throw new Error(
+			"abDivisions must be provided when hasAbDivisions is enabled.",
+		);
 
 	const slots = creator.getSlots();
 
 	if (abDivisions.length !== slots.length)
-		throw Error("abDivisions length must match the seeding length.");
+		throw new Error("abDivisions length must match the seeding length.");
 
 	const divisionA: ParticipantSlot[] = [];
 	const divisionB: ParticipantSlot[] = [];
@@ -79,13 +81,13 @@ function getAbDivisionGroups(creator: StageCreator): {
 	for (let i = 0; i < slots.length; i++) {
 		const slot = slots[i];
 		if (slot === null)
-			throw Error("BYEs are not supported with A/B divisions.");
+			throw new Error("BYEs are not supported with A/B divisions.");
 
 		const division = abDivisions[i];
 		if (division === 0) divisionA.push(slot);
 		else if (division === 1) divisionB.push(slot);
 		else
-			throw Error(
+			throw new Error(
 				`Participant at seed ${i + 1} is missing an A/B division assignment.`,
 			);
 	}
diff --git a/app/features/tournament-bracket/core/engine/create/swiss.ts b/app/features/tournament-bracket/core/engine/create/swiss.ts
index facdeff44..2cb0e10aa 100644
--- a/app/features/tournament-bracket/core/engine/create/swiss.ts
+++ b/app/features/tournament-bracket/core/engine/create/swiss.ts
@@ -86,7 +86,7 @@ function firstRoundMatches({
 				id: matchId++,
 				groupId: groupIdx,
 				stageId: 0,
-				roundId: roundId,
+				roundId,
 				number: i + 1,
 				opponent1: {
 					id: upper,
@@ -103,7 +103,7 @@ function firstRoundMatches({
 				id: matchId++,
 				groupId: groupIdx,
 				stageId: 0,
-				roundId: roundId,
+				roundId,
 				number: upperHalf.length + 1,
 				opponent1: {
 					id: bye,
diff --git a/app/features/tournament-bracket/core/engine/propagation/dropped-teams.ts b/app/features/tournament-bracket/core/engine/propagation/dropped-teams.ts
index 241106aa1..02aba3bbf 100644
--- a/app/features/tournament-bracket/core/engine/propagation/dropped-teams.ts
+++ b/app/features/tournament-bracket/core/engine/propagation/dropped-teams.ts
@@ -32,7 +32,7 @@ export function endDroppedTeamMatches(
 		})();
 
 		const stored = store.matchById(match.id);
-		if (!stored) throw Error("Match not found.");
+		if (!stored) throw new Error("Match not found.");
 
 		propagator.updateMatch(
 			stored,
diff --git a/app/features/tournament-bracket/core/engine/propagation/reset-result.ts b/app/features/tournament-bracket/core/engine/propagation/reset-result.ts
index 781572fd7..4daf6cd70 100644
--- a/app/features/tournament-bracket/core/engine/propagation/reset-result.ts
+++ b/app/features/tournament-bracket/core/engine/propagation/reset-result.ts
@@ -17,13 +17,13 @@ export function resetMatchResults(
 	const propagator = new Propagator(store);
 
 	const stored = store.matchById(matchId);
-	if (!stored) throw Error("Match not found.");
+	if (!stored) throw new Error("Match not found.");
 
 	const stage = store.stageById(stored.stageId);
-	if (!stage) throw Error("Stage not found.");
+	if (!stage) throw new Error("Stage not found.");
 
 	const group = store.groupById(stored.groupId);
-	if (!group) throw Error("Group not found.");
+	if (!group) throw new Error("Group not found.");
 
 	const { roundNumber, roundCount } = propagator.getRoundPositionalInfo(
 		stored.roundId,
@@ -48,7 +48,7 @@ export function resetMatchResults(
 				!isMatchByeCompleted(match),
 		)
 	)
-		throw Error("The match is locked.");
+		throw new Error("The match is locked.");
 
 	helpers.clearWinner(stored);
 	store.markMatchChanged(stored);
diff --git a/app/features/tournament-bracket/core/engine/propagation/set.ts b/app/features/tournament-bracket/core/engine/propagation/set.ts
index c8cd949bd..dbf067ebc 100644
--- a/app/features/tournament-bracket/core/engine/propagation/set.ts
+++ b/app/features/tournament-bracket/core/engine/propagation/set.ts
@@ -123,5 +123,5 @@ function sideOfTeam(match: MatchData, teamId: number): 0 | 1 {
 	if (match.opponent1?.id === teamId) return 0;
 	if (match.opponent2?.id === teamId) return 1;
 
-	throw Error(`Team id ${teamId} is not in the match`);
+	throw new Error(`Team id ${teamId} is not in the match`);
 }
diff --git a/app/features/tournament-bracket/core/engine/propagation/store.ts b/app/features/tournament-bracket/core/engine/propagation/store.ts
index e7b11411f..9cdf3d93a 100644
--- a/app/features/tournament-bracket/core/engine/propagation/store.ts
+++ b/app/features/tournament-bracket/core/engine/propagation/store.ts
@@ -82,7 +82,7 @@ export class Store {
 	/** Records that a match row of this store was mutated. */
 	markMatchChanged(match: MatchData): void {
 		if (this.matchesById.get(match.id) !== match)
-			throw Error("Match is not a row of this store.");
+			throw new Error("Match is not a row of this store.");
 
 		this.changedMatchIds.add(match.id);
 	}
diff --git a/app/features/tournament-bracket/core/engine/propagation/traversal.ts b/app/features/tournament-bracket/core/engine/propagation/traversal.ts
index 97e38455d..07a10363b 100644
--- a/app/features/tournament-bracket/core/engine/propagation/traversal.ts
+++ b/app/features/tournament-bracket/core/engine/propagation/traversal.ts
@@ -31,10 +31,10 @@ export class Propagator {
 		);
 
 		const stage = this.store.stageById(match.stageId);
-		if (!stage) throw Error("Stage not found.");
+		if (!stage) throw new Error("Stage not found.");
 
 		const group = this.store.groupById(match.groupId);
-		if (!group) throw Error("Group not found.");
+		if (!group) throw new Error("Group not found.");
 
 		const matchLocation = helpers.getMatchLocation(stage.type, group.number);
 
@@ -48,10 +48,10 @@ export class Propagator {
 		force?: boolean,
 	): void {
 		if (!force && matchStatus(this.store.data, stored.id) === "PENDING")
-			throw Error("The match is locked.");
+			throw new Error("The match is locked.");
 
 		const stage = this.store.stageById(stored.stageId);
-		if (!stage) throw Error("Stage not found.");
+		if (!stage) throw new Error("Stage not found.");
 
 		const resultChanged = helpers.setMatchResults(
 			stored,
@@ -137,7 +137,7 @@ export class Propagator {
 		winnerSide?: Side,
 	): void {
 		if (matchLocation === "final_group") {
-			if (!nextMatches[0]) throw Error("First next match is null.");
+			if (!nextMatches[0]) throw new Error("First next match is null.");
 			setNextOpponent(nextMatches[0], "opponent1", match, "opponent1");
 			setNextOpponent(nextMatches[0], "opponent2", match, "opponent2");
 			this.store.markMatchChanged(nextMatches[0]);
@@ -157,7 +157,7 @@ export class Propagator {
 		}
 
 		if (nextMatches.length !== 2) return;
-		if (!nextMatches[1]) throw Error("Second next match is null.");
+		if (!nextMatches[1]) throw new Error("Second next match is null.");
 
 		// Second match is the consolation final (SE) or a loser bracket match (DE).
 		if (matchLocation === "single_bracket") {
@@ -193,7 +193,7 @@ export class Propagator {
 
 	getRoundPositionalInfo(roundId: number): RoundPositionalInfo {
 		const round = this.store.roundById(roundId);
-		if (!round) throw Error("Round not found.");
+		if (!round) throw new Error("Round not found.");
 
 		return {
 			roundNumber: round.number,
@@ -228,7 +228,7 @@ export class Propagator {
 			case "final_group":
 				return this.getNextMatchesFinal(match, roundNumber, roundCount);
 			default:
-				throw Error("Unknown bracket kind.");
+				throw new Error("Unknown bracket kind.");
 		}
 	}
 
@@ -378,7 +378,7 @@ export class Propagator {
 	/** The only bracket in single elimination, the winner bracket in double elimination. */
 	private getUpperBracket(stageId: number): GroupData {
 		const winnerBracket = this.store.groupByNumber(stageId, 1);
-		if (!winnerBracket) throw Error("Winner bracket not found.");
+		if (!winnerBracket) throw new Error("Winner bracket not found.");
 		return winnerBracket;
 	}
 
@@ -386,7 +386,7 @@ export class Propagator {
 	private participantCount(stageId: number): number {
 		const upperBracket = this.getUpperBracket(stageId);
 		const firstRound = this.store.roundByNumber(upperBracket.id, 1);
-		if (!firstRound) throw Error("First round not found.");
+		if (!firstRound) throw new Error("First round not found.");
 
 		return this.store.matchCountInRound(firstRound.id) * 2;
 	}
@@ -424,11 +424,11 @@ export class Propagator {
 	): MatchData {
 		const round = this.store.roundByNumber(groupId, roundNumber);
 
-		if (!round) throw Error("Round not found.");
+		if (!round) throw new Error("Round not found.");
 
 		const match = this.store.matchByNumber(round.id, matchNumber);
 
-		if (!match) throw Error("Match not found.");
+		if (!match) throw new Error("Match not found.");
 
 		return match;
 	}
diff --git a/app/features/tournament-bracket/core/toMapList.ts b/app/features/tournament-bracket/core/toMapList.ts
index 8be6e3eea..1ca1be847 100644
--- a/app/features/tournament-bracket/core/toMapList.ts
+++ b/app/features/tournament-bracket/core/toMapList.ts
@@ -142,9 +142,9 @@ function sortRounds(
 				doubleEliminationGroupRank(b.groupId);
 			if (rankDiff !== 0) return rankDiff;
 		}
-		if (type === "single_elimination") {
-			// finals and 3rd place match last
-			if (a.groupId !== b.groupId) return a.groupId - b.groupId;
+		// finals and 3rd place match last
+		if (type === "single_elimination" && a.groupId !== b.groupId) {
+			return a.groupId - b.groupId;
 		}
 
 		return a.number - b.number;
diff --git a/app/features/tournament-bracket/routes/to.$id.brackets.finalize.tsx b/app/features/tournament-bracket/routes/to.$id.brackets.finalize.tsx
index 4bd128d38..5a1164248 100644
--- a/app/features/tournament-bracket/routes/to.$id.brackets.finalize.tsx
+++ b/app/features/tournament-bracket/routes/to.$id.brackets.finalize.tsx
@@ -207,7 +207,7 @@ function NewBadgeReceiversSelector({
 					tournament.minMembersPerTeam === newOwnerStanding.members.length;
 
 				newReceivers.push({
-					badgeId: badgeId,
+					badgeId,
 					tournamentTeamId: newOwnerTournamentTeamId,
 					userIds: defaultSelected
 						? newOwnerStanding.members.map((m) => m.userId)
diff --git a/app/features/tournament/tournament-utils.ts b/app/features/tournament/tournament-utils.ts
index c1b45a3f6..cac429c33 100644
--- a/app/features/tournament/tournament-utils.ts
+++ b/app/features/tournament/tournament-utils.ts
@@ -435,7 +435,7 @@ export function getBracketProgressionLabel(
 		while (j < prefix.length && j < name.length && prefix[j] === name[j]) {
 			j++;
 		}
-		prefix = prefix.substring(0, j);
+		prefix = prefix.slice(0, j);
 		if (prefix === "") break;
 	}
 
diff --git a/app/features/trophies/components/Trophy.tsx b/app/features/trophies/components/Trophy.tsx
index 8937e716e..f91c5ec98 100644
--- a/app/features/trophies/components/Trophy.tsx
+++ b/app/features/trophies/components/Trophy.tsx
@@ -127,7 +127,7 @@ export function Trophy({
 
 			try {
 				viewer.setState(JSON.parse(modelState));
-			} catch (_) {
+			} catch {
 				setError(true);
 				return;
 			}
diff --git a/app/features/user-page/core/widgets/widget-form-schemas.ts b/app/features/user-page/core/widgets/widget-form-schemas.ts
index ee7dfac69..195c4a7b6 100644
--- a/app/features/user-page/core/widgets/widget-form-schemas.ts
+++ b/app/features/user-page/core/widgets/widget-form-schemas.ts
@@ -206,7 +206,7 @@ function pastedTierListUrlToSearchParams(value: string) {
 	if (!value.includes("/tier-list-maker")) return value;
 
 	try {
-		return new URL(value, "https://sendou.ink").search.substring(1);
+		return new URL(value, "https://sendou.ink").search.slice(1);
 	} catch {
 		return value;
 	}
diff --git a/app/features/vods/vods-schemas.ts b/app/features/vods/vods-schemas.ts
index c1be22d23..1378163ce 100644
--- a/app/features/vods/vods-schemas.ts
+++ b/app/features/vods/vods-schemas.ts
@@ -38,7 +38,7 @@ const videoMatchSchema = v.object({
 			"Invalid time format. Use HH:MM:SS or MM:SS",
 		),
 	),
-	stageId: stageId,
+	stageId,
 	mode: modeShort,
 	weapons: v.array(weaponSplId),
 });
diff --git a/app/hooks/useAutoRerender.ts b/app/hooks/useAutoRerender.ts
index 3290fbdd3..721aa86cc 100644
--- a/app/hooks/useAutoRerender.ts
+++ b/app/hooks/useAutoRerender.ts
@@ -58,8 +58,7 @@ function getTickStore(everyMs: number, alignToMs: number): TickStore {
  * Rerenders periodically, returning the latest tick's `Date`: consume it so React Compiler can't memoize the
  * rerender away. Components on the same interval and `alignTo` share one timer, ticking at exactly `alignTo + N*interval`.
  */
-export function useAutoRerender(): Date;
-export function useAutoRerender(every: "second" | "ten seconds"): Date;
+export function useAutoRerender(every?: "second" | "ten seconds"): Date;
 export function useAutoRerender(
 	every: "minute",
 	options: AutoRerenderOptions,
diff --git a/app/modules/i18n/resources.server.ts b/app/modules/i18n/resources.server.ts
index ee6a938c1..2a8d83fb7 100644
--- a/app/modules/i18n/resources.server.ts
+++ b/app/modules/i18n/resources.server.ts
@@ -496,34 +496,34 @@ export const resources = {
 		welcome: welcomeEsUs,
 	},
 	en: {
-		gear: gear,
-		faq: faq,
-		forms: forms,
-		friends: friends,
-		weapons: weapons,
+		gear,
+		faq,
+		forms,
+		friends,
+		weapons,
 		schedule: scheduleEn,
 		scrims: scrimsEn,
-		settings: settings,
-		common: common,
+		settings,
+		common,
 		"game-badges": gameBadges,
 		"game-misc": gameMisc,
-		tournament: tournament,
-		front: front,
-		user: user,
-		q: q,
-		art: art,
-		builds: builds,
-		lfg: lfg,
-		vods: vods,
-		calendar: calendar,
-		org: org,
-		params: params,
-		badges: badges,
-		contributions: contributions,
-		team: team,
-		trophies: trophies,
+		tournament,
+		front,
+		user,
+		q,
+		art,
+		builds,
+		lfg,
+		vods,
+		calendar,
+		org,
+		params,
+		badges,
+		contributions,
+		team,
+		trophies,
 		"tier-list-maker": tierListMaker,
-		analyzer: analyzer,
+		analyzer,
 		welcome: welcomeEn,
 	},
 	ko: {
diff --git a/app/modules/virtualizer/core.ts b/app/modules/virtualizer/core.ts
index 59d5f6bb9..559e18ba0 100644
--- a/app/modules/virtualizer/core.ts
+++ b/app/modules/virtualizer/core.ts
@@ -25,11 +25,11 @@ export interface VirtualItem {
  */
 export class VirtualizerCore {
 	private count: number;
-	private estimatedSize: number;
-	private gap: number;
-	private overscan: number;
-	private measuredSizes = new Map<number, number>();
-	private offsets: number[] = [];
+	private readonly estimatedSize: number;
+	private readonly gap: number;
+	private readonly overscan: number;
+	private readonly measuredSizes = new Map<number, number>();
+	private readonly offsets: number[] = [];
 	/** Entries of `offsets` before this index are up to date. */
 	private validOffsets = 0;
 
diff --git a/app/routines/routine.server.ts b/app/routines/routine.server.ts
index 39ff15901..f09c765f9 100644
--- a/app/routines/routine.server.ts
+++ b/app/routines/routine.server.ts
@@ -2,7 +2,7 @@ import { logger } from "../utils/logger";
 
 export class Routine {
 	readonly name;
-	private func;
+	private readonly func;
 
 	constructor({
 		name,
diff --git a/app/utils/compression.ts b/app/utils/compression.ts
index e00031083..503d35e6c 100644
--- a/app/utils/compression.ts
+++ b/app/utils/compression.ts
@@ -15,7 +15,7 @@ export function compressToBase64(
 	const base64 = btoa(binary);
 	if (!options?.urlSafe) return base64;
 
-	return base64.replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
+	return base64.replace(/\+/g, "-").replace(/\//g, "_").replace(/[=]+$/, "");
 }
 
 /**
diff --git a/app/utils/oklch-gamut.ts b/app/utils/oklch-gamut.ts
index 308083b03..74c4fa762 100644
--- a/app/utils/oklch-gamut.ts
+++ b/app/utils/oklch-gamut.ts
@@ -103,7 +103,7 @@ function compute_max_saturation(a: number, b: number): number {
 		const f1 = wl * l_dS + wm * m_dS + ws * s_dS;
 		const f2 = wl * l_dS2 + wm * m_dS2 + ws * s_dS2;
 
-		S = S - (f * f1) / (f1 * f1 - 0.5 * f * f2);
+		S -= (f * f1) / (f1 * f1 - 0.5 * f * f2);
 	}
 
 	return S;
diff --git a/biome.json b/biome.json
index fe68e703b..ab867a183 100644
--- a/biome.json
+++ b/biome.json
@@ -99,6 +99,20 @@
 				"useSymbolDescription": "error",
 				"useGroupedAccessorPairs": "error",
 				"useSpreadOverApply": "error",
+				"useCollapsedIf": {
+					"fix": "safe",
+					"level": "error"
+				},
+				"useConsistentObjectDefinitions": {
+					"fix": "safe",
+					"level": "error"
+				},
+				"useThrowNewError": "error",
+				"useShorthandAssign": "error",
+				"useFragmentSyntax": "error",
+				"noSubstr": "error",
+				"useUnifiedTypeSignatures": "error",
+				"useReadonlyClassProperties": "error",
 				"useFilenamingConvention": {
 					"level": "error",
 					"options": {
@@ -122,7 +136,16 @@
 				"useWhile": {
 					"fix": "safe",
 					"level": "error"
-				}
+				},
+				"noUselessStringConcat": {
+					"fix": "safe",
+					"level": "error"
+				},
+				"noDivRegex": {
+					"fix": "safe",
+					"level": "error"
+				},
+				"noUselessCatchBinding": "error"
 			},
 			"performance": {
 				"noSyncScripts": "error"
diff --git a/scripts/scanner/build-glyph-atlas.ts b/scripts/scanner/build-glyph-atlas.ts
index 1db909ef5..acfe0fda5 100644
--- a/scripts/scanner/build-glyph-atlas.ts
+++ b/scripts/scanner/build-glyph-atlas.ts
@@ -111,7 +111,7 @@ const NAME_GREEK = "ια"; // ι: "Rιppιng_H", α: "◇Dαrz™" (special-symb
  * Scoreboard-names only (not death-tag) until attested, like NAME_GREEK.
  */
 const NAME_SYMBOLS =
-	"′‘’‚‛…″“”„←→↑↓⇒⇔˜€∞√∀⊂⊃∴∵∂№♭♀♂◎◇◆△▲▽▼†※™" + "『』【】〈〉《》〔〕々〆〇〃～";
+	"′‘’‚‛…″“”„←→↑↓⇒⇔˜€∞√∀⊂⊃∴∵∂№♭♀♂◎◇◆△▲▽▼†※™『』【】〈〉《》〔〕々〆〇〃～";
 
 /**
  * Render the key char but emit it as the value: in-game names show "•" as a