diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 7549c66..0b68d36 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -38,6 +38,8 @@ import {
   CallSplit,
   ContentCopy,
   Delete,
+  Link,
+  LinkOff,
   MyLocation,
   Settings,
   SkipNext,
@@ -133,8 +135,22 @@ export default function App() {
   const [job, setJob] = useState<Job | null>(null);
   const [outputs, setOutputs] = useState<string[]>([]);
   const [isUploading, setIsUploading] = useState(false);
+  const [uploadProgress, setUploadProgress] = useState(0);
   const [error, setError] = useState<string | null>(null);
 
+  type SegmentRow = {
+    kind: "intro" | "core" | "outro";
+    label: string;
+    start: number;
+    end: number;
+    startEditable: boolean;
+    endEditable: boolean;
+    coreIndex?: number;
+  };
+
+  const [isLinked, setIsLinked] = useState(true);
+  const [customSegmentRows, setCustomSegmentRows] = useState<SegmentRow[]>([]);
+
   const videoRef = useRef<HTMLVideoElement | null>(null);
 
   useEffect(() => {
@@ -340,16 +356,6 @@ export default function App() {
     return Array.from(markMap.values()).sort((a, b) => a.value - b.value);
   }, [markers, project, duration]);
 
-  type SegmentRow = {
-    kind: "intro" | "core" | "outro";
-    label: string;
-    start: number;
-    end: number;
-    startEditable: boolean;
-    endEditable: boolean;
-    coreIndex?: number;
-  };
-
   const introBoundary = useMemo(() => {
     if (!project) return 0;
     const maxDuration = duration || project.intro_seconds;
@@ -394,7 +400,7 @@ export default function App() {
     });
   }, [duration, coreBoundaries, frameStep]);
 
-  const segmentRows = useMemo(() => {
+  const derivedSegmentRows = useMemo(() => {
     if (!duration || !project || coreBoundaries.length < 2) return [] as SegmentRow[];
     const introEnd = Math.max(0, introBoundary - frameStep);
     const outroStart = clamp(alignedOutroBoundary, 0, duration);
@@ -430,6 +436,8 @@ export default function App() {
     return rows;
   }, [duration, project, coreBoundaries, introBoundary, alignedOutroBoundary, lastFrameTime, frameStep, segments]);
 
+  const segmentRows = isLinked ? derivedSegmentRows : customSegmentRows;
+
   useEffect(() => {
     if (!segmentRows.length) {
       setSegmentDrafts([]);
@@ -602,9 +610,12 @@ export default function App() {
     if (videoFiles.length === 0) return;
     setError(null);
     setIsUploading(true);
+    setUploadProgress(0);
 
     try {
-      const uploadedItems = await uploadVideos(videoFiles);
+      const uploadedItems = await uploadVideos(videoFiles, (index, total, progress) => {
+        setUploadProgress((index + progress) / total);
+      });
       const uploaded = uploadedItems[0];
       await refreshVideos();
       if (uploaded) {
@@ -616,6 +627,7 @@ export default function App() {
         setOutputs([]);
         setJob(null);
         setOutputPrefix(uploaded.filename.replace(/\.[^.]+$/, ""));
+        setIsLinked(true);
       }
       setVideoFiles([]);
       setPreviewUrl("");
@@ -639,6 +651,7 @@ export default function App() {
     setOutputPrefix(item.filename.replace(/\.[^.]+$/, ""));
     setVideoFiles([]);
     setPreviewUrl("");
+    setIsLinked(true);
     try {
       const response = await listMarkers(item.id);
       setMarkers(normalizeMarkers(response.markers ?? []));
@@ -799,6 +812,17 @@ export default function App() {
     }
 
     const snapped = snapToFrame(parsed);
+
+    if (!isLinked) {
+      setCustomSegmentRows((prev) => {
+        const next = [...prev];
+        next[rowIndex] = { ...next[rowIndex], [field]: snapped };
+        return next;
+      });
+      setPendingSegmentEditPersist(true);
+      return;
+    }
+
     let boundaryIndex = -1;
     let boundaryValue = snapped;
 
@@ -854,6 +878,12 @@ export default function App() {
 
   const handleDeleteSegment = async (row: SegmentRow) => {
     setError(null);
+    if (!isLinked) {
+      setCustomSegmentRows((prev) => prev.filter((r) => r !== row));
+      setPendingSegmentEditPersist(true);
+      return;
+    }
+
     if (row.kind === "intro") {
       await saveProject({ intro_seconds: 0 });
       setPendingSegmentEditPersist(true);
@@ -1014,6 +1044,14 @@ export default function App() {
                       Project settings
                     </Button>
                   </Box>
+                  {isUploading && (
+                    <Box sx={{ mt: 1 }}>
+                      <LinearProgress variant="determinate" value={uploadProgress * 100} />
+                      <Typography variant="body2" color="text.secondary" sx={{ mt: 0.5 }}>
+                        Uploading... {Math.round(uploadProgress * 100)}%
+                      </Typography>
+                    </Box>
+                  )}
                   <Box>
                     <Stack direction="row" spacing={1} alignItems="center" sx={{ mb: 1 }}>
                       <Typography variant="subtitle2">Recent uploads</Typography>
@@ -1355,6 +1393,19 @@ export default function App() {
                       <Button variant="outlined" onClick={handleSaveMarkers} disabled={!video || markers.length === 0}>
                         Save markers
                       </Button>
+                      <Button
+                        variant="outlined"
+                        startIcon={isLinked ? <LinkOff /> : <Link />}
+                        onClick={() => {
+                          if (isLinked) {
+                            setCustomSegmentRows(derivedSegmentRows);
+                          }
+                          setIsLinked(!isLinked);
+                        }}
+                        disabled={!duration}
+                      >
+                        {isLinked ? "Unlink timestamps" : "Link timestamps"}
+                      </Button>
                     </Stack>
                   </Grid>
                   <Grid item xs={12}>
diff --git a/frontend/src/api.ts b/frontend/src/api.ts
index c07f248..6a0b43c 100644
--- a/frontend/src/api.ts
+++ b/frontend/src/api.ts
@@ -116,10 +116,54 @@ export async function replaceMarkers(
   });
 }
 
-export async function uploadVideos(files: File[]): Promise<Video[]> {
+export async function uploadVideoWithProgress(file: File, onProgress?: (progress: number) => void): Promise<Video> {
+  return new Promise((resolve, reject) => {
+    const xhr = new XMLHttpRequest();
+    xhr.open("POST", `${apiBase}/api/videos/upload`);
+    
+    xhr.upload.onprogress = (event) => {
+      if (event.lengthComputable && onProgress) {
+        onProgress(event.loaded / event.total);
+      }
+    };
+    
+    xhr.onload = () => {
+      if (xhr.status >= 200 && xhr.status < 300) {
+        try {
+          resolve(JSON.parse(xhr.responseText));
+        } catch {
+          reject(new ApiError(xhr.status, "Invalid response"));
+        }
+      } else {
+        let message = `Request failed (${xhr.status})`;
+        try {
+          const data = JSON.parse(xhr.responseText);
+          if (data?.detail) message = data.detail;
+          else if (data?.message) message = data.message;
+        } catch {}
+        reject(new ApiError(xhr.status, message));
+      }
+    };
+    
+    xhr.onerror = () => reject(new ApiError(0, "Network error"));
+    
+    const formData = new FormData();
+    formData.append("file", file);
+    xhr.send(formData);
+  });
+}
+
+export async function uploadVideos(
+  files: File[], 
+  onProgress?: (index: number, total: number, fileProgress: number) => void
+): Promise<Video[]> {
   const uploaded: Video[] = [];
-  for (const file of files) {
-    uploaded.push(await uploadVideo(file));
+  for (let i = 0; i < files.length; i++) {
+    const file = files[i];
+    const video = await uploadVideoWithProgress(file, (progress) => {
+      if (onProgress) onProgress(i, files.length, progress);
+    });
+    uploaded.push(video);
   }
   return uploaded;
 }
diff --git a/patch.py b/patch.py
new file mode 100644
index 0000000..9b01a13
--- /dev/null
+++ b/patch.py
@@ -0,0 +1,253 @@
+import sys
+
+def patch_file():
+    with open('frontend/src/App.tsx', 'r', encoding='utf-8') as f:
+        content = f.read()
+
+    # 1. Add state variables
+    old1 = '''  const [job, setJob] = useState<Job | null>(null);
+  const [outputs, setOutputs] = useState<string[]>([]);
+  const [isUploading, setIsUploading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const videoRef = useRef<HTMLVideoElement | null>(null);'''
+    new1 = '''  const [job, setJob] = useState<Job | null>(null);
+  const [outputs, setOutputs] = useState<string[]>([]);
+  const [isUploading, setIsUploading] = useState(false);
+  const [uploadProgress, setUploadProgress] = useState(0);
+  const [error, setError] = useState<string | null>(null);
+
+  type SegmentRow = {
+    kind: "intro" | "core" | "outro";
+    label: string;
+    start: number;
+    end: number;
+    startEditable: boolean;
+    endEditable: boolean;
+    coreIndex?: number;
+  };
+
+  const [isLinked, setIsLinked] = useState(true);
+  const [customSegmentRows, setCustomSegmentRows] = useState<SegmentRow[]>([]);
+
+  const videoRef = useRef<HTMLVideoElement | null>(null);'''
+    if old1 not in content: print('Failed old1')
+    content = content.replace(old1, new1)
+
+    # 2. Remove duplicate SegmentRow type declaration
+    old2 = '''  type SegmentRow = {
+    kind: "intro" | "core" | "outro";
+    label: string;
+    start: number;
+    end: number;
+    startEditable: boolean;
+    endEditable: boolean;
+    coreIndex?: number;
+  };
+
+  const introBoundary = useMemo(() => {'''
+    new2 = '''  const introBoundary = useMemo(() => {'''
+    if old2 not in content: print('Failed old2')
+    content = content.replace(old2, new2)
+
+    # 3. Rename segmentRows to derivedSegmentRows
+    old3 = '''  const segmentRows = useMemo(() => {
+    if (!duration || !project || coreBoundaries.length < 2) return [] as SegmentRow[];'''
+    new3 = '''  const derivedSegmentRows = useMemo(() => {
+    if (!duration || !project || coreBoundaries.length < 2) return [] as SegmentRow[];'''
+    if old3 not in content: print('Failed old3')
+    content = content.replace(old3, new3)
+
+    # 4. Add segmentRows constant
+    old4 = '''    });
+    return rows;
+  }, [duration, project, coreBoundaries, introBoundary, alignedOutroBoundary, lastFrameTime, frameStep, segments]);
+
+  useEffect(() => {
+    if (!segmentRows.length) {'''
+    new4 = '''    });
+    return rows;
+  }, [duration, project, coreBoundaries, introBoundary, alignedOutroBoundary, lastFrameTime, frameStep, segments]);
+
+  const segmentRows = isLinked ? derivedSegmentRows : customSegmentRows;
+
+  useEffect(() => {
+    if (!segmentRows.length) {'''
+    if old4 not in content: print('Failed old4')
+    content = content.replace(old4, new4)
+
+    # 5. handleUpload changes
+    old5 = '''  const handleUpload = async () => {
+    if (!project) {
+      setError("Configure project settings before uploading.");
+      setProjectDrawerOpen(true);
+      return;
+    }
+    if (videoFiles.length === 0) return;
+    setError(null);
+    setIsUploading(true);
+
+    try {
+      const uploadedItems = await uploadVideos(videoFiles);'''
+    new5 = '''  const handleUpload = async () => {
+    if (!project) {
+      setError("Configure project settings before uploading.");
+      setProjectDrawerOpen(true);
+      return;
+    }
+    if (videoFiles.length === 0) return;
+    setError(null);
+    setIsUploading(true);
+    setUploadProgress(0);
+
+    try {
+      const uploadedItems = await uploadVideos(videoFiles, (index, total, progress) => {
+        setUploadProgress((index + progress) / total);
+      });'''
+    if old5 not in content: print('Failed old5')
+    content = content.replace(old5, new5)
+
+    # 6. handleUpload linked reset
+    old6 = '''        setJob(null);
+        setOutputPrefix(uploaded.filename.replace(/\.[^.]+$/, ""));
+      }
+      setVideoFiles([]);'''
+    new6 = '''        setJob(null);
+        setOutputPrefix(uploaded.filename.replace(/\.[^.]+$/, ""));
+        setIsLinked(true);
+      }
+      setVideoFiles([]);'''
+    if old6 not in content: print('Failed old6')
+    content = content.replace(old6, new6)
+
+    # 7. handleSelectVideo reset
+    old7 = '''    setOutputPrefix(item.filename.replace(/\.[^.]+$/, ""));
+    setVideoFiles([]);
+    setPreviewUrl("");
+    try {'''
+    new7 = '''    setOutputPrefix(item.filename.replace(/\.[^.]+$/, ""));
+    setVideoFiles([]);
+    setPreviewUrl("");
+    setIsLinked(true);
+    try {'''
+    if old7 not in content: print('Failed old7')
+    content = content.replace(old7, new7)
+
+    # 8. commitSegmentDraft bypass
+    old8 = '''    const snapped = snapToFrame(parsed);
+    let boundaryIndex = -1;
+    let boundaryValue = snapped;'''
+    new8 = '''    const snapped = snapToFrame(parsed);
+
+    if (!isLinked) {
+      setCustomSegmentRows((prev) => {
+        const next = [...prev];
+        next[rowIndex] = { ...next[rowIndex], [field]: snapped };
+        return next;
+      });
+      setPendingSegmentEditPersist(true);
+      return;
+    }
+
+    let boundaryIndex = -1;
+    let boundaryValue = snapped;'''
+    if old8 not in content: print('Failed old8')
+    content = content.replace(old8, new8)
+
+    # 9. handleDeleteSegment bypass
+    old9 = '''  const handleDeleteSegment = async (row: SegmentRow) => {
+    setError(null);
+    if (row.kind === "intro") {'''
+    new9 = '''  const handleDeleteSegment = async (row: SegmentRow) => {
+    setError(null);
+    if (!isLinked) {
+      setCustomSegmentRows((prev) => prev.filter((r) => r !== row));
+      setPendingSegmentEditPersist(true);
+      return;
+    }
+
+    if (row.kind === "intro") {'''
+    if old9 not in content: print('Failed old9')
+    content = content.replace(old9, new9)
+
+    # 10. upload progress UI
+    old10 = '''                  <Box>
+                    <Button
+                      variant="contained"
+                      onClick={handleUpload}
+                      disabled={videoFiles.length === 0 || isBusy || !project}
+                    >
+                      {isUploading ? "Uploading..." : "Upload to Backend"}
+                    </Button>
+                    <Button sx={{ ml: 1 }} onClick={() => setProjectDrawerOpen(true)}>
+                      Project settings
+                    </Button>
+                  </Box>
+                  <Box>
+                    <Stack direction="row" spacing={1} alignItems="center" sx={{ mb: 1 }}>'''
+    new10 = '''                  <Box>
+                    <Button
+                      variant="contained"
+                      onClick={handleUpload}
+                      disabled={videoFiles.length === 0 || isBusy || !project}
+                    >
+                      {isUploading ? "Uploading..." : "Upload to Backend"}
+                    </Button>
+                    <Button sx={{ ml: 1 }} onClick={() => setProjectDrawerOpen(true)}>
+                      Project settings
+                    </Button>
+                  </Box>
+                  {isUploading && (
+                    <Box sx={{ mt: 1 }}>
+                      <LinearProgress variant="determinate" value={uploadProgress * 100} />
+                      <Typography variant="body2" color="text.secondary" sx={{ mt: 0.5 }}>
+                        Uploading... {Math.round(uploadProgress * 100)}%
+                      </Typography>
+                    </Box>
+                  )}
+                  <Box>
+                    <Stack direction="row" spacing={1} alignItems="center" sx={{ mb: 1 }}>'''
+    if old10 not in content: print('Failed old10')
+    content = content.replace(old10, new10)
+
+    # 11. segments table unlink button
+    old11 = '''                  <Grid item xs={12}>
+                    <Stack direction={{ xs: "column", sm: "row" }} spacing={2} alignItems={{ sm: "center" }}>
+                      <Button variant="outlined" onClick={handleAddMarker} disabled={!duration}>
+                        Add marker at playhead
+                      </Button>
+                      <Button variant="outlined" onClick={handleSaveMarkers} disabled={!video || markers.length === 0}>
+                        Save markers
+                      </Button>
+                    </Stack>
+                  </Grid>'''
+    new11 = '''                  <Grid item xs={12}>
+                    <Stack direction={{ xs: "column", sm: "row" }} spacing={2} alignItems={{ sm: "center" }}>
+                      <Button variant="outlined" onClick={handleAddMarker} disabled={!duration}>
+                        Add marker at playhead
+                      </Button>
+                      <Button variant="outlined" onClick={handleSaveMarkers} disabled={!video || markers.length === 0}>
+                        Save markers
+                      </Button>
+                      <Button
+                        variant="outlined"
+                        startIcon={isLinked ? <LinkOff /> : <Link />}
+                        onClick={() => {
+                          if (isLinked) {
+                            setCustomSegmentRows(derivedSegmentRows);
+                          }
+                          setIsLinked(!isLinked);
+                        }}
+                        disabled={!duration}
+                      >
+                        {isLinked ? "Unlink timestamps" : "Link timestamps"}
+                      </Button>
+                    </Stack>
+                  </Grid>'''
+    if old11 not in content: print('Failed old11')
+    content = content.replace(old11, new11)
+
+    with open('frontend/src/App.tsx', 'w', encoding='utf-8') as f:
+        f.write(content)
+
+patch_file()