diff --git a/src/lib/services/annotation-service.ts b/src/lib/services/annotation-service.ts
index 97f38f7..196c132 100644
--- a/src/lib/services/annotation-service.ts
+++ b/src/lib/services/annotation-service.ts
@@ -6,6 +6,8 @@ import type { CreateAnnotationInput, UpdateAnnotationInput } from "@/lib/validat
 import { createFeedbackFromAnnotation } from "@/lib/services/feedback-service";
 import { extractThumbnail, isFFmpegAvailable } from "@/lib/services/video-service";
 
+const BASE_PATH = process.env.NEXT_PUBLIC_BASE_PATH ?? "";
+
 const VIDEO_UPLOADS_DIR =
   process.env.VIDEO_UPLOADS_DIR ||
   (process.env.NODE_ENV === "production"
@@ -140,7 +142,7 @@ async function extractAnnotationFrameThumbnail(
   const created = await extractThumbnail(videoPath, thumbPath, timestampSeconds);
 
   if (created) {
-    const thumbUrl = `/api/uploads/revisions/${revisionId}/annotation_frames/${thumbFilename}`;
+    const thumbUrl = `${BASE_PATH}/api/uploads/revisions/${revisionId}/annotation_frames/${thumbFilename}`;
     await prisma.annotation.update({
       where: { id: annotationId },
       data: { frameThumbnailUrl: thumbUrl },
diff --git a/src/lib/services/upload-service.ts b/src/lib/services/upload-service.ts
index 36cb200..4b3fd3a 100644
--- a/src/lib/services/upload-service.ts
+++ b/src/lib/services/upload-service.ts
@@ -11,6 +11,9 @@ import {
   transcodeToHLS,
 } from "@/lib/services/video-service";
 
+/** Base path prefix so stored URLs work when the app is mounted at a sub-path */
+const BASE_PATH = process.env.NEXT_PUBLIC_BASE_PATH ?? "";
+
 /** Images stored alongside videos in the mounted volume, served via /api/uploads */
 const UPLOADS_DIR =
   process.env.VIDEO_UPLOADS_DIR
@@ -92,7 +95,7 @@ export async function processAndStoreImage(
   const ext = file.type === "image/tiff" ? "tiff" : "png";
   const filename = `${imageType}_${timestamp}.${ext}`;
   const filePath = path.join(revisionDir, filename);
-  const url = `/api/uploads/revisions/${revisionId}/${filename}`;
+  const url = `${BASE_PATH}/api/uploads/revisions/${revisionId}/${filename}`;
 
   let originalUrl: string | undefined;
 
@@ -102,7 +105,7 @@ export async function processAndStoreImage(
     const originalFilename = `${imageType}_${timestamp}_original.png`;
     const originalPath = path.join(revisionDir, originalFilename);
     await writeFile(originalPath, buffer);
-    originalUrl = `/api/uploads/revisions/${revisionId}/${originalFilename}`;
+    originalUrl = `${BASE_PATH}/api/uploads/revisions/${revisionId}/${originalFilename}`;
 
     // Flatten onto white background
     const flattened = await sharp(buffer)
@@ -115,7 +118,7 @@ export async function processAndStoreImage(
     const originalFilename = `${imageType}_${timestamp}_original.tiff`;
     const originalPath = path.join(revisionDir, originalFilename);
     await writeFile(originalPath, buffer);
-    originalUrl = `/api/uploads/revisions/${revisionId}/${originalFilename}`;
+    originalUrl = `${BASE_PATH}/api/uploads/revisions/${revisionId}/${originalFilename}`;
 
     const converted = await sharp(buffer).png().toBuffer();
     const pngFilename = `${imageType}_${timestamp}.png`;
@@ -225,7 +228,7 @@ export async function processAndStoreVideo(
   const timestamp = Date.now();
   const videoFilename = `${videoType}_${timestamp}.mp4`;
   const videoPath = path.join(revisionDir, videoFilename);
-  const videoUrl = `/api/uploads/revisions/${revisionId}/${videoFilename}`;
+  const videoUrl = `${BASE_PATH}/api/uploads/revisions/${revisionId}/${videoFilename}`;
 
   // Stream-write the file to disk
   const arrayBuffer = await file.arrayBuffer();
@@ -241,12 +244,12 @@ export async function processAndStoreVideo(
   const thumbTime = Math.min(1, metadata.duration * 0.1 || 1);
   const thumbCreated = await extractThumbnail(videoPath, thumbPath, thumbTime);
   const thumbnailUrl = thumbCreated
-    ? `/api/uploads/revisions/${revisionId}/${thumbFilename}`
+    ? `${BASE_PATH}/api/uploads/revisions/${revisionId}/${thumbFilename}`
     : null;
 
   // HLS output paths
   const hlsDir = path.join(revisionDir, `${videoType}_${timestamp}_hls`);
-  const hlsUrl = `/api/uploads/revisions/${revisionId}/${videoType}_${timestamp}_hls/index.m3u8`;
+  const hlsUrl = `${BASE_PATH}/api/uploads/revisions/${revisionId}/${videoType}_${timestamp}_hls/index.m3u8`;
 
   const uploaded: UploadedVideo = {
     url: videoUrl,