diff --git a/app/api/avatars/[userId]/route.ts b/app/api/avatars/[userId]/route.ts
index fb1a917..a957144 100644
--- a/app/api/avatars/[userId]/route.ts
+++ b/app/api/avatars/[userId]/route.ts
@@ -1,8 +1,6 @@
 import path from "node:path";
 import { type NextRequest, NextResponse } from "next/server";
-
-const DATA_DIR = process.env.DATA_DIR || "./data";
-const AVATAR_DIR = path.join(DATA_DIR, "avatars");
+import { AVATAR_DIR } from "@/lib/constants";
 
 const IMMUTABLE_CACHE = "public, max-age=31536000, immutable";
 
diff --git a/lib/actions/settings.ts b/lib/actions/settings.ts
index 9ad1770..7f60f51 100644
--- a/lib/actions/settings.ts
+++ b/lib/actions/settings.ts
@@ -7,6 +7,7 @@ import { headers } from "next/headers";
 import { z } from "zod";
 import { auth } from "@/lib/auth/server";
 import { requireAdmin, requireSession } from "@/lib/auth/session";
+import { AVATAR_DIR } from "@/lib/constants";
 import { type BackupFrequency, rescheduleBackup, triggerJob } from "@/lib/cron";
 import { db } from "@/lib/db/client";
 import { integrations } from "@/lib/db/schema";
@@ -268,8 +269,6 @@ export async function getUpdateCheckAction(): Promise<UpdateCheckResult | null>
 
 // --- Avatar actions ---
 
-const DATA_DIR = process.env.DATA_DIR || "./data";
-const AVATAR_DIR = path.join(DATA_DIR, "avatars");
 const MAX_AVATAR_SIZE = 2 * 1024 * 1024; // 2MB
 const ALLOWED_AVATAR_TYPES = new Set([
   "image/jpeg",
diff --git a/lib/constants.ts b/lib/constants.ts
new file mode 100644
index 0000000..a295331
--- /dev/null
+++ b/lib/constants.ts
@@ -0,0 +1,20 @@
+import path from "node:path";
+
+export const DATA_DIR = process.env.DATA_DIR || "./data";
+
+export const DATABASE_URL =
+  process.env.DATABASE_URL || path.join(DATA_DIR, "sqlite.db");
+
+export const CACHE_DIR = process.env.CACHE_DIR
+  ? path.join(process.env.CACHE_DIR, "images")
+  : path.join(DATA_DIR, "images");
+
+export const BACKUP_DIR = path.join(DATA_DIR, "backups");
+
+export const AVATAR_DIR = path.join(DATA_DIR, "avatars");
+
+export const TMDB_API_BASE_URL =
+  process.env.TMDB_API_BASE_URL || "https://api.themoviedb.org/3";
+
+export const TMDB_IMAGE_BASE_URL =
+  process.env.TMDB_IMAGE_BASE_URL || "https://image.tmdb.org/t/p";
diff --git a/lib/db/client.ts b/lib/db/client.ts
index 253d5d5..4d9cbc4 100644
--- a/lib/db/client.ts
+++ b/lib/db/client.ts
@@ -1,7 +1,7 @@
 import { Database } from "bun:sqlite";
-import path from "node:path";
 import type { Logger } from "drizzle-orm";
 import { drizzle } from "drizzle-orm/bun-sqlite";
+import { DATABASE_URL } from "@/lib/constants";
 import { createLogger } from "@/lib/logger";
 import * as schema from "./schema";
 
@@ -29,10 +29,6 @@ const globalForDb = globalThis as unknown as {
   _client: Database | undefined;
 };
 
-const DATABASE_URL =
-  process.env.DATABASE_URL ||
-  path.join(process.env.DATA_DIR || "./data", "sqlite.db");
-
 function getClient() {
   if (!globalForDb._client) {
     globalForDb._client = new Database(DATABASE_URL);
diff --git a/lib/services/backup.ts b/lib/services/backup.ts
index e713fe7..c62a52c 100644
--- a/lib/services/backup.ts
+++ b/lib/services/backup.ts
@@ -4,17 +4,13 @@ import { mkdir, readdir } from "node:fs/promises";
 import path from "node:path";
 import { format } from "date-fns";
 import { sql } from "drizzle-orm";
+import { BACKUP_DIR, DATABASE_URL } from "@/lib/constants";
 import { closeDatabase, db } from "@/lib/db/client";
 import { runMigrations } from "@/lib/db/migrate";
 import { createLogger } from "@/lib/logger";
 
 const log = createLogger("backup");
 
-const DATA_DIR = process.env.DATA_DIR || "./data";
-const DATABASE_URL =
-  process.env.DATABASE_URL || path.join(DATA_DIR, "sqlite.db");
-const BACKUP_DIR = path.join(DATA_DIR, "backups");
-
 const MANUAL_PATTERN = /^sofa-manual-\d{4}-\d{2}-\d{2}-\d{6}(?:\d{3})?\.db$/;
 const SCHEDULED_PATTERN =
   /^sofa-scheduled-\d{4}-\d{2}-\d{2}-\d{6}(?:\d{3})?\.db$/;
diff --git a/lib/services/image-cache.ts b/lib/services/image-cache.ts
index dba2c74..f2d5b02 100644
--- a/lib/services/image-cache.ts
+++ b/lib/services/image-cache.ts
@@ -1,6 +1,7 @@
 import { mkdir, rename } from "node:fs/promises";
 import path from "node:path";
 import { eq, inArray } from "drizzle-orm";
+import { CACHE_DIR, TMDB_IMAGE_BASE_URL } from "@/lib/constants";
 import { db } from "@/lib/db/client";
 import {
   availabilityOffers,
@@ -29,14 +30,6 @@ const CATEGORY_SIZES: Record<ImageCategory, string> = {
   profiles: "w185",
 };
 
-const IMAGE_BASE_URL =
-  process.env.TMDB_IMAGE_BASE_URL || "https://image.tmdb.org/t/p";
-
-const DATA_DIR = process.env.DATA_DIR || "./data";
-const CACHE_DIR = process.env.CACHE_DIR
-  ? path.join(process.env.CACHE_DIR, "images")
-  : path.join(DATA_DIR, "images");
-
 export function imageCacheEnabled(): boolean {
   return process.env.IMAGE_CACHE_ENABLED !== "false";
 }
@@ -76,7 +69,7 @@ export async function downloadAndCacheImage(
   category: ImageCategory,
 ): Promise<Buffer | null> {
   const size = CATEGORY_SIZES[category];
-  const url = `${IMAGE_BASE_URL}/${size}${tmdbPath}`;
+  const url = `${TMDB_IMAGE_BASE_URL}/${size}${tmdbPath}`;
 
   const res = await fetch(url);
   if (!res.ok) {
@@ -121,7 +114,7 @@ export async function fetchAndMaybeCache(
 
   // Fetch from TMDB
   const size = CATEGORY_SIZES[category];
-  const url = `${IMAGE_BASE_URL}/${size}${tmdbPath}`;
+  const url = `${TMDB_IMAGE_BASE_URL}/${size}${tmdbPath}`;
   const res = await fetch(url);
   if (!res.ok) {
     log.warn(`Fetch failed: ${url} -> ${res.status}`);
diff --git a/lib/services/system-health.ts b/lib/services/system-health.ts
index a895a15..a8256c8 100644
--- a/lib/services/system-health.ts
+++ b/lib/services/system-health.ts
@@ -1,6 +1,12 @@
 import { access, constants, readdir } from "node:fs/promises";
 import path from "node:path";
 import { count, desc, eq } from "drizzle-orm";
+import {
+  CACHE_DIR,
+  DATA_DIR,
+  DATABASE_URL,
+  TMDB_API_BASE_URL,
+} from "@/lib/constants";
 import { db } from "@/lib/db/client";
 import { cronRuns, episodes, titles, user } from "@/lib/db/schema";
 import { listBackups } from "@/lib/services/backup";
@@ -8,15 +14,6 @@ import { imageCacheEnabled } from "@/lib/services/image-cache";
 import { getSetting } from "@/lib/services/settings";
 import { isUpdateCheckEnabled } from "@/lib/services/update-check";
 
-const DATA_DIR = process.env.DATA_DIR || "./data";
-const DATABASE_URL =
-  process.env.DATABASE_URL || path.join(DATA_DIR, "sqlite.db");
-const CACHE_DIR = process.env.CACHE_DIR
-  ? path.join(process.env.CACHE_DIR, "images")
-  : path.join(DATA_DIR, "images");
-const TMDB_API_BASE_URL =
-  process.env.TMDB_API_BASE_URL || "https://api.themoviedb.org/3";
-
 export interface SystemHealthData {
   database: {
     dbSizeBytes: number;
diff --git a/lib/tmdb/client.ts b/lib/tmdb/client.ts
index 57a525f..eda3758 100644
--- a/lib/tmdb/client.ts
+++ b/lib/tmdb/client.ts
@@ -1,3 +1,4 @@
+import { TMDB_API_BASE_URL } from "@/lib/constants";
 import { createLogger } from "@/lib/logger";
 import type {
   TmdbExternalIds,
@@ -18,9 +19,6 @@ import type {
 } from "./types";
 
 const log = createLogger("tmdb");
-
-const BASE_URL =
-  process.env.TMDB_API_BASE_URL || "https://api.themoviedb.org/3";
 function getApiKey() {
   const key = process.env.TMDB_API_READ_ACCESS_TOKEN;
   if (!key) throw new Error("TMDB_API_READ_ACCESS_TOKEN is not set");
@@ -32,7 +30,7 @@ async function tmdbFetch<T>(
   params?: Record<string, string>,
   fetchOptions?: RequestInit,
 ): Promise<T> {
-  const url = new URL(`${BASE_URL}${path}`);
+  const url = new URL(`${TMDB_API_BASE_URL}${path}`);
   if (params) {
     for (const [k, v] of Object.entries(params)) {
       url.searchParams.set(k, v);