diff --git a/batch_detect.py b/batch_detect.py
deleted file mode 100644
index 1ed4a3e..0000000
--- a/batch_detect.py
+++ /dev/null
@@ -1,183 +0,0 @@
-#!/usr/bin/env python3
-"""
-Batch Singing Detector
-=======================
-Process multiple stream recordings at once.
-Point it at a folder of recordings and it will process each one.
-
-Usage:
-  python batch_detect.py "D:\\streams"
-  python batch_detect.py "D:\\streams" --output-dir "D:\\singing_edits" --auto-cut
-  python batch_detect.py "D:\\streams" --pattern "*.mp4" --recursive
-"""
-
-import argparse
-import os
-import sys
-import time
-import glob
-from pathlib import Path
-
-
-def find_videos(input_dir: str, pattern: str = "*", recursive: bool = False, 
-                extensions: tuple = (".mp4", ".mkv", ".flv", ".ts", ".avi", ".mov", ".webm")) -> list:
-    """Find all video files in directory."""
-    videos = []
-    
-    if recursive:
-        for ext in extensions:
-            videos.extend(glob.glob(os.path.join(input_dir, "**", f"*{ext}"), recursive=True))
-    else:
-        for ext in extensions:
-            videos.extend(glob.glob(os.path.join(input_dir, f"*{ext}")))
-    
-    # Filter by pattern if specified
-    if pattern != "*":
-        videos = [v for v in videos if Path(v).match(pattern)]
-    
-    # Sort by modification time (newest first)
-    videos.sort(key=lambda x: os.path.getmtime(x), reverse=True)
-    
-    return videos
-
-
-def main():
-    parser = argparse.ArgumentParser(
-        description="Batch process multiple stream recordings for singing detection.",
-    )
-    
-    parser.add_argument("input_dir", help="Directory containing stream recordings")
-    parser.add_argument("--output-dir", "-o", default=None,
-                        help="Output directory (default: same as input)")
-    parser.add_argument("--pattern", default="*",
-                        help="Filename pattern to match (default: all video files)")
-    parser.add_argument("--recursive", "-r", action="store_true",
-                        help="Search subdirectories recursively")
-    parser.add_argument("--gap", "-g", type=float, default=10.0,
-                        help="Max gap to merge singing segments (default: 10s)")
-    parser.add_argument("--min-duration", "-m", type=float, default=20.0,
-                        help="Minimum segment duration (default: 20s)")
-    parser.add_argument("--padding", "-p", type=float, default=2.0,
-                        help="Padding before/after segments (default: 2s)")
-    parser.add_argument("--fps", type=float, default=29.97,
-                        help="Frame rate (default: 29.97)")
-    parser.add_argument("--auto-cut", action="store_true",
-                        help="Generate auto-cut ffmpeg scripts")
-    parser.add_argument("--skip-existing", action="store_true",
-                        help="Skip files that already have output .edl files")
-    parser.add_argument("--limit", type=int, default=0,
-                        help="Process only N files (0 = all)")
-    
-    args = parser.parse_args()
-    
-    if not os.path.isdir(args.input_dir):
-        print(f"[ERROR] Directory not found: {args.input_dir}")
-        sys.exit(1)
-    
-    # Find videos
-    videos = find_videos(args.input_dir, args.pattern, args.recursive)
-    
-    if not videos:
-        print(f"[INFO] No video files found in: {args.input_dir}")
-        sys.exit(0)
-    
-    # Filter already-processed files
-    if args.skip_existing:
-        output_dir = args.output_dir or args.input_dir
-        unprocessed = []
-        for v in videos:
-            stem = Path(v).stem
-            edl = os.path.join(output_dir, f"{stem}_singing.edl")
-            if not os.path.exists(edl):
-                unprocessed.append(v)
-            else:
-                print(f"[SKIP] Already processed: {Path(v).name}")
-        videos = unprocessed
-    
-    # Apply limit
-    if args.limit > 0:
-        videos = videos[:args.limit]
-    
-    print(f"\n{'='*60}")
-    print(f"  Batch Singing Detector")
-    print(f"{'='*60}")
-    print(f"  Input:    {args.input_dir}")
-    print(f"  Videos:   {len(videos)} to process")
-    print(f"{'='*60}\n")
-    
-    # Process each video
-    # Import the main detect_singing module
-    sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
-    from detect_singing import (
-        extract_audio, run_segmentation, merge_singing_segments,
-        export_edl, export_csv, export_davinci_markers_csv,
-        export_json, export_ffmpeg_concat, format_timecode,
-    )
-    
-    results = []
-    for i, video_path in enumerate(videos, 1):
-        video_name = Path(video_path).name
-        print(f"\n{'─'*60}")
-        print(f"  [{i}/{len(videos)}] Processing: {video_name}")
-        print(f"{'─'*60}")
-        
-        try:
-            output_dir = args.output_dir or os.path.dirname(video_path)
-            os.makedirs(output_dir, exist_ok=True)
-            
-            stem = Path(video_path).stem
-            wav_path = os.path.join(output_dir, f"{stem}_audio.wav")
-            
-            # Step 1-3
-            extract_audio(video_path, wav_path)
-            raw_segments = run_segmentation(wav_path)
-            singing = merge_singing_segments(
-                raw_segments, 
-                max_gap=args.gap,
-                min_duration=args.min_duration,
-                padding=args.padding,
-            )
-            
-            # Step 4: Export
-            if singing:
-                edl = os.path.join(output_dir, f"{stem}_singing.edl")
-                csv_f = os.path.join(output_dir, f"{stem}_singing.csv")
-                markers = os.path.join(output_dir, f"{stem}_markers.csv")
-                json_f = os.path.join(output_dir, f"{stem}_singing.json")
-                
-                export_edl(singing, edl, fps=args.fps,
-                          source_filename=Path(video_path).name)
-                export_csv(singing, csv_f)
-                export_davinci_markers_csv(singing, markers, fps=args.fps)
-                export_json(singing, json_f)
-                
-                if args.auto_cut:
-                    export_ffmpeg_concat(singing, video_path, json_f)
-                
-                total_dur = sum(s["duration"] for s in singing)
-                results.append((video_name, len(singing), total_dur, "OK"))
-            else:
-                results.append((video_name, 0, 0, "No songs found"))
-            
-            # Cleanup WAV
-            if os.path.exists(wav_path):
-                os.remove(wav_path)
-                
-        except Exception as e:
-            print(f"  [ERROR] {e}")
-            results.append((video_name, 0, 0, f"Error: {e}"))
-    
-    # Summary
-    print(f"\n\n{'='*60}")
-    print(f"  BATCH COMPLETE")
-    print(f"{'='*60}")
-    print(f"  {'Video':<40s} {'Songs':>5s}  {'Singing Time':>12s}  Status")
-    print(f"  {'─'*40} {'─'*5}  {'─'*12}  {'─'*15}")
-    for name, count, dur, status in results:
-        name_short = name[:38] + ".." if len(name) > 40 else name
-        print(f"  {name_short:<40s} {count:>5d}  {format_timecode(dur):>12s}  {status}")
-    print(f"{'='*60}")
-
-
-if __name__ == "__main__":
-    main()
diff --git a/core/exporters.py b/core/exporters.py
new file mode 100644
index 0000000..6e22306
--- /dev/null
+++ b/core/exporters.py
@@ -0,0 +1,188 @@
+"""
+Export singing segments to various formats:
+  - EDL (DaVinci Resolve timeline import)
+  - CSV (human-readable)
+  - DaVinci Resolve Markers CSV
+  - JSON (programmatic)
+  - ffmpeg concat script (auto-cut)
+"""
+
+import csv
+import json
+import os
+import sys
+from pathlib import Path
+
+from utils.formats import format_timecode, seconds_to_smpte
+
+
+def export_edl(segments: list, output_path: str, fps: float = 29.97,
+               title: str = "Singing Segments", source_filename: str = None):
+    """Export EDL file for DaVinci Resolve."""
+    if source_filename:
+        clip_name = source_filename
+        reel_name_safe = Path(source_filename).stem[:32].replace(" ", "_")
+    else:
+        clip_name = None
+        reel_name_safe = "001"
+
+    rec_offset = 3600.0
+
+    with open(output_path, "w", encoding="utf-8") as f:
+        f.write(f"TITLE: {title}\n")
+        f.write("FCM: NON-DROP FRAME\n\n")
+
+        current_rec_pos = rec_offset
+        for seg in segments:
+            edit_num = f"{seg['index']:03d}"
+            src_in = seconds_to_smpte(seg["start"], fps)
+            src_out = seconds_to_smpte(seg["end"], fps)
+            rec_in = seconds_to_smpte(current_rec_pos, fps)
+            rec_out = seconds_to_smpte(current_rec_pos + seg["duration"], fps)
+
+            f.write(f"{edit_num}  {reel_name_safe}  V     C        {src_in} {src_out} {rec_in} {rec_out}\n")
+
+            if clip_name:
+                f.write(f"* FROM CLIP NAME: {clip_name}\n")
+
+            f.write(f"* COMMENT: Song {seg['index']} - Duration {seg['duration']:.0f}s\n\n")
+            current_rec_pos += seg["duration"]
+
+
+def export_csv(segments: list, output_path: str):
+    """Export singing segments as CSV."""
+    with open(output_path, "w", newline="", encoding="utf-8") as f:
+        writer = csv.writer(f)
+        writer.writerow(["index", "start_sec", "end_sec", "duration_sec",
+                         "start_timecode", "end_timecode"])
+        for seg in segments:
+            writer.writerow([
+                seg["index"],
+                f"{seg['start']:.2f}",
+                f"{seg['end']:.2f}",
+                f"{seg['duration']:.1f}",
+                format_timecode(seg["start"]),
+                format_timecode(seg["end"]),
+            ])
+
+
+def export_markers_csv(segments: list, output_path: str, fps: float = 29.97):
+    """Export DaVinci Resolve Markers CSV."""
+    with open(output_path, "w", newline="", encoding="utf-8") as f:
+        writer = csv.writer(f)
+        writer.writerow(["#", "Color", "Name", "Start TC", "End TC", "Duration TC", "Notes"])
+        for seg in segments:
+            writer.writerow([
+                seg["index"],
+                "Blue",
+                f"Song {seg['index']}",
+                seconds_to_smpte(seg["start"], fps),
+                seconds_to_smpte(seg["end"], fps),
+                seconds_to_smpte(seg["duration"], fps),
+                f"Duration: {seg['duration']:.0f}s",
+            ])
+
+
+def export_json(segments: list, output_path: str):
+    """Export as JSON."""
+    with open(output_path, "w", encoding="utf-8") as f:
+        json.dump(segments, f, indent=2, ensure_ascii=False)
+
+
+def export_ffmpeg_script(segments: list, video_path: str, output_dir: str):
+    """
+    Export a script that uses ffmpeg to cut and concatenate all
+    singing segments into a single video file.
+    """
+    video_name = Path(video_path).stem
+    ext = Path(video_path).suffix
+    out_video = str(Path(output_dir) / f"{video_name}_singing_only{ext}")
+
+    is_windows = os.name == "nt" or sys.platform == "win32"
+    script_ext = ".bat" if is_windows else ".sh"
+    script_path = str(Path(output_dir) / f"{video_name}_autocut{script_ext}")
+    concat_list_path = str(Path(output_dir) / f"{video_name}_concat_list.txt")
+
+    lines = []
+    if is_windows:
+        lines.append("@echo off")
+        lines.append("REM Auto-generated ffmpeg script to extract singing segments")
+        lines.append(f'REM Source: {video_path}')
+        lines.append("")
+    else:
+        lines.append("#!/bin/bash")
+        lines.append("# Auto-generated ffmpeg script to extract singing segments")
+        lines.append(f'# Source: {video_path}')
+        lines.append("")
+
+    segment_files = []
+    for seg in segments:
+        seg_file = f"_seg_{seg['index']:03d}{ext}"
+        seg_path = str(Path(output_dir) / seg_file)
+        segment_files.append(seg_file)
+
+        cmd = (f'ffmpeg -y -ss {seg["start"]:.2f} -i "{video_path}" '
+               f'-t {seg["duration"]:.2f} -c copy "{seg_path}"')
+        lines.append(f"echo Extracting Song {seg['index']}...")
+        lines.append(cmd)
+        lines.append("")
+
+    lines.append("echo Creating concat list...")
+    if is_windows:
+        lines.append("(")
+        for sf in segment_files:
+            seg_path = str(Path(output_dir) / sf)
+            lines.append(f"  echo file '{seg_path}'")
+        lines.append(f') > "{concat_list_path}"')
+    else:
+        for i, sf in enumerate(segment_files):
+            seg_path = str(Path(output_dir) / sf)
+            op = ">" if i == 0 else ">>"
+            lines.append(f"echo \"file '{seg_path}'\" {op} \"{concat_list_path}\"")
+
+    lines.append("")
+    lines.append("echo Concatenating all segments...")
+    lines.append(f'ffmpeg -y -f concat -safe 0 -i "{concat_list_path}" -c copy "{out_video}"')
+    lines.append("")
+    lines.append("echo Cleaning up temp files...")
+
+    for sf in segment_files:
+        seg_path = str(Path(output_dir) / sf)
+        if is_windows:
+            lines.append(f'del "{seg_path}"')
+        else:
+            lines.append(f'rm -f "{seg_path}"')
+    if is_windows:
+        lines.append(f'del "{concat_list_path}"')
+    else:
+        lines.append(f'rm -f "{concat_list_path}"')
+
+    lines.append("")
+    lines.append(f'echo Done! Output: {out_video}')
+    if is_windows:
+        lines.append("pause")
+
+    with open(script_path, "w", encoding="utf-8") as f:
+        f.write("\n".join(lines))
+
+    if not is_windows:
+        os.chmod(script_path, 0o755)
+
+    return script_path
+
+
+def export_raw_segments(segments: list, output_path: str):
+    """Export ALL raw segments (speech/music/noise) as CSV for debugging."""
+    with open(output_path, "w", newline="", encoding="utf-8") as f:
+        writer = csv.writer(f)
+        writer.writerow(["label", "start_sec", "end_sec", "duration_sec",
+                         "start_timecode", "end_timecode"])
+        for label, start, end in segments:
+            writer.writerow([
+                label,
+                f"{start:.2f}",
+                f"{end:.2f}",
+                f"{end - start:.1f}",
+                format_timecode(start),
+                format_timecode(end),
+            ])
diff --git a/core/fftools.py b/core/fftools.py
new file mode 100644
index 0000000..d3a7ac1
--- /dev/null
+++ b/core/fftools.py
@@ -0,0 +1,99 @@
+"""
+ffmpeg / ffprobe discovery and probing helpers.
+Shared by both concat and singing detection features.
+"""
+
+import json
+import os
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+# ── Suppress console windows on Windows ──────────────────────────────────────
+_NO_WINDOW: dict = {}
+if sys.platform == "win32":
+    _NO_WINDOW["creationflags"] = subprocess.CREATE_NO_WINDOW
+
+
+def app_dir() -> str:
+    if getattr(sys, "frozen", False):
+        return os.path.dirname(sys.executable)
+    return os.path.dirname(os.path.abspath(__file__))
+
+
+def find_tool(name: str) -> str | None:
+    """Locate ffmpeg / ffprobe next to the exe / script, then on PATH."""
+    base = app_dir()
+    for sub in ["_internal", "..", ""]:
+        for variant in [name + ".exe", name]:
+            p = os.path.join(base, sub, variant)
+            if os.path.exists(p):
+                return os.path.abspath(p)
+    return shutil.which(name + ".exe") or shutil.which(name)
+
+
+def probe_duration(path: str, ffprobe_bin: str | None = None) -> float:
+    """Get video/audio duration in seconds via ffprobe."""
+    ffprobe = ffprobe_bin or find_tool("ffprobe")
+    if not ffprobe:
+        return 0.0
+    try:
+        r = subprocess.run(
+            [ffprobe, "-v", "error",
+             "-show_entries", "format=duration",
+             "-of", "json", path],
+            stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+            text=True, timeout=20,
+            **_NO_WINDOW,
+        )
+        if r.returncode != 0:
+            return 0.0
+        data = json.loads(r.stdout or "{}")
+        return max(0.0, float(data.get("format", {}).get("duration", 0) or 0))
+    except Exception:
+        return 0.0
+
+
+def extract_audio(video_path: str, output_wav: str,
+                  ffmpeg_bin: str | None = None,
+                  progress_cb=None) -> str:
+    """
+    Extract audio from video file as 16kHz mono WAV.
+    Required format for inaSpeechSegmenter.
+    
+    progress_cb: optional callable(message: str) for status updates.
+    """
+    ffmpeg = ffmpeg_bin or find_tool("ffmpeg")
+    if not ffmpeg:
+        raise FileNotFoundError("ffmpeg not found. Install ffmpeg and add to PATH.")
+
+    if progress_cb:
+        progress_cb(f"Extracting audio from: {Path(video_path).name}")
+
+    cmd = [
+        ffmpeg,
+        "-i", video_path,
+        "-vn",
+        "-acodec", "pcm_s16le",
+        "-ar", "16000",
+        "-ac", "1",
+        "-y",
+        output_wav,
+    ]
+
+    result = subprocess.run(
+        cmd,
+        capture_output=True,
+        text=True,
+        timeout=1800,
+        **_NO_WINDOW,
+    )
+    if result.returncode != 0:
+        raise RuntimeError(f"ffmpeg failed:\n{result.stderr[-500:]}")
+
+    if progress_cb:
+        size_mb = os.path.getsize(output_wav) / (1024 * 1024)
+        progress_cb(f"Audio extracted: {size_mb:.1f} MB")
+
+    return output_wav
diff --git a/core/segmenter.py b/core/segmenter.py
new file mode 100644
index 0000000..b30bba8
--- /dev/null
+++ b/core/segmenter.py
@@ -0,0 +1,118 @@
+"""
+Singing segment detection via inaSpeechSegmenter.
+
+Pipeline:
+  1. Run inaSpeechSegmenter to classify speech/music/noise
+  2. Filter for 'music' segments (singing voice is classified as music)
+  3. Merge nearby segments, apply padding, filter by minimum duration
+"""
+
+import time
+from utils.formats import format_timecode
+
+
+def check_segmenter_available() -> tuple[bool, str]:
+    """Check if inaSpeechSegmenter is installed."""
+    try:
+        from inaSpeechSegmenter import Segmenter  # noqa: F401
+        return True, ""
+    except ImportError:
+        return False, (
+            "inaSpeechSegmenter is not installed.\n\n"
+            "Install it with:\n"
+            "  pip install inaSpeechSegmenter\n\n"
+            "You also need TensorFlow:\n"
+            "  pip install tensorflow[and-cuda]   (GPU)\n"
+            "  pip install tensorflow              (CPU)"
+        )
+
+
+def run_segmentation(wav_path: str, progress_cb=None) -> list:
+    """
+    Run inaSpeechSegmenter on audio file.
+    Returns list of (label, start_sec, end_sec) tuples.
+    Labels: 'music', 'speech', 'noise', 'noEnergy'
+    """
+    from inaSpeechSegmenter import Segmenter
+
+    if progress_cb:
+        progress_cb("Loading segmentation model…")
+
+    start_time = time.time()
+    seg = Segmenter(vad_engine='smn', detect_gender=False)
+
+    if progress_cb:
+        progress_cb("Running audio segmentation (this may take a while)…")
+
+    segments = seg(wav_path)
+    elapsed = time.time() - start_time
+
+    if progress_cb:
+        progress_cb(f"Segmentation complete in {elapsed:.1f}s — {len(segments)} raw segments")
+
+    return segments
+
+
+def merge_singing_segments(
+    segments: list,
+    max_gap: float = 10.0,
+    min_duration: float = 20.0,
+    padding: float = 2.0,
+) -> list:
+    """
+    Filter for 'music' segments and merge nearby ones.
+    
+    Returns list of dicts:
+        [{"index", "start", "end", "duration", "original_start", "original_end"}, ...]
+    """
+    music_segs = [(start, end) for label, start, end in segments if label == "music"]
+
+    if not music_segs:
+        return []
+
+    music_segs.sort(key=lambda x: x[0])
+
+    # Merge segments with gaps smaller than max_gap
+    merged = []
+    current_start, current_end = music_segs[0]
+
+    for start, end in music_segs[1:]:
+        if start - current_end <= max_gap:
+            current_end = max(current_end, end)
+        else:
+            merged.append((current_start, current_end))
+            current_start, current_end = start, end
+    merged.append((current_start, current_end))
+
+    # Apply padding and minimum duration filter
+    results = []
+    idx = 1
+    for start, end in merged:
+        duration = end - start
+        if duration >= min_duration:
+            padded_start = max(0, start - padding)
+            padded_end = end + padding
+            results.append({
+                "index": idx,
+                "start": padded_start,
+                "end": padded_end,
+                "duration": padded_end - padded_start,
+                "original_start": start,
+                "original_end": end,
+            })
+            idx += 1
+
+    return results
+
+
+def get_segment_stats(segments: list) -> dict:
+    """Get summary statistics from raw segmentation output."""
+    type_counts = {}
+    type_durations = {}
+    for label, start, end in segments:
+        type_counts[label] = type_counts.get(label, 0) + 1
+        type_durations[label] = type_durations.get(label, 0) + (end - start)
+    return {
+        "counts": type_counts,
+        "durations": type_durations,
+    }
diff --git a/detect_singing.py b/detect_singing.py
deleted file mode 100644
index e8dbef4..0000000
--- a/detect_singing.py
+++ /dev/null
@@ -1,598 +0,0 @@
-#!/usr/bin/env python3
-"""
-Singing Segment Detector for Live Stream Recordings
-=====================================================
-Detects singing segments in long stream recordings and exports
-DaVinci Resolve-compatible EDL markers for fast video editing.
-
-Pipeline:
-  1. Extract audio from video (ffmpeg → 16kHz mono WAV)
-  2. Run inaSpeechSegmenter to classify speech/music/noise
-  3. Merge nearby "music" segments (singing) with configurable gap
-  4. Export to EDL (Edit Decision List) for DaVinci Resolve import
-  5. Optionally export CSV for review
-
-Usage:
-  python detect_singing.py "path/to/stream_recording.mp4"
-  python detect_singing.py "path/to/stream_recording.mp4" --gap 15 --min-duration 30
-  python detect_singing.py "path/to/stream_recording.mp4" --output-dir "D:/singing_edits"
-"""
-
-import argparse
-import csv
-import json
-import os
-import subprocess
-import sys
-import tempfile
-import time
-from pathlib import Path
-
-
-# ──────────────────────────────────────────────
-# Step 1: Extract audio from video using ffmpeg
-# ──────────────────────────────────────────────
-def extract_audio(video_path: str, output_wav: str, ffmpeg_bin: str = "ffmpeg") -> str:
-    """Extract audio from video file as 16kHz mono WAV (required by inaSpeechSegmenter)."""
-    print(f"\n[Step 1/4] Extracting audio from: {video_path}")
-    print(f"           Output WAV: {output_wav}")
-
-    cmd = [
-        ffmpeg_bin,
-        "-i", video_path,
-        "-vn",                  # no video
-        "-acodec", "pcm_s16le", # 16-bit PCM
-        "-ar", "16000",         # 16kHz sample rate
-        "-ac", "1",             # mono
-        "-y",                   # overwrite
-        output_wav,
-    ]
-
-    try:
-        result = subprocess.run(
-            cmd,
-            capture_output=True,
-            text=True,
-            timeout=1800,  # 30 min timeout for very long files
-        )
-        if result.returncode != 0:
-            print(f"  [ERROR] ffmpeg failed:\n{result.stderr[-500:]}")
-            sys.exit(1)
-    except FileNotFoundError:
-        print(f"  [ERROR] ffmpeg not found at '{ffmpeg_bin}'.")
-        print(f"          Make sure ffmpeg is installed and in your PATH.")
-        sys.exit(1)
-
-    size_mb = os.path.getsize(output_wav) / (1024 * 1024)
-    print(f"           Audio extracted: {size_mb:.1f} MB")
-    return output_wav
-
-
-# ──────────────────────────────────────────────
-# Step 2: Run inaSpeechSegmenter
-# ──────────────────────────────────────────────
-def run_segmentation(wav_path: str) -> list:
-    """
-    Run inaSpeechSegmenter on audio file.
-    Returns list of (label, start_sec, end_sec) tuples.
-    Labels: 'music', 'speech', 'male', 'female', 'noise', 'noEnergy'
-    
-    NOTE: inaSpeechSegmenter classifies singing voice as 'music'.
-    """
-    print(f"\n[Step 2/4] Running audio segmentation (this may take a while)...")
-
-    try:
-        from inaSpeechSegmenter import Segmenter
-    except ImportError:
-        print("  [ERROR] inaSpeechSegmenter is not installed.")
-        print("          Install it with: pip install inaSpeechSegmenter")
-        sys.exit(1)
-
-    start_time = time.time()
-
-    # vad_engine='smn' → speech/music/noise detection
-    # detect_gender=False → faster, we don't need gender info
-    seg = Segmenter(vad_engine='smn', detect_gender=False)
-    segments = seg(wav_path)
-
-    elapsed = time.time() - start_time
-    print(f"           Segmentation complete in {elapsed:.1f}s")
-    print(f"           Total segments found: {len(segments)}")
-
-    # Count segment types
-    type_counts = {}
-    type_durations = {}
-    for label, start, end in segments:
-        type_counts[label] = type_counts.get(label, 0) + 1
-        type_durations[label] = type_durations.get(label, 0) + (end - start)
-
-    for label in sorted(type_counts.keys()):
-        count = type_counts[label]
-        dur = type_durations[label]
-        print(f"           {label:>10s}: {count:4d} segments, {format_timecode(dur)} total")
-
-    return segments
-
-
-# ──────────────────────────────────────────────
-# Step 3: Filter & merge singing (music) segments
-# ──────────────────────────────────────────────
-def merge_singing_segments(
-    segments: list,
-    max_gap: float = 10.0,
-    min_duration: float = 20.0,
-    padding: float = 2.0,
-) -> list:
-    """
-    Filter for 'music' segments (which includes singing) and merge
-    nearby segments that are likely the same song.
-    
-    Args:
-        segments:     Raw segmentation output [(label, start, end), ...]
-        max_gap:      Max gap (seconds) between music segments to merge them.
-                      Stream singers often have brief pauses, audience interaction
-                      between verses, etc. Default 10s works well.
-        min_duration: Minimum duration (seconds) for a merged segment to be kept.
-                      Filters out short music stings, sound effects, etc.
-                      A typical song is 2-5 minutes, so 20s is a safe minimum.
-        padding:      Seconds to add before/after each segment for clean cuts.
-    
-    Returns:
-        List of dicts: [{"start": float, "end": float, "duration": float, "index": int}, ...]
-    """
-    print(f"\n[Step 3/4] Merging singing segments (gap={max_gap}s, min={min_duration}s, pad={padding}s)")
-
-    # Extract only music segments
-    music_segs = [(start, end) for label, start, end in segments if label == "music"]
-
-    if not music_segs:
-        print("           No music segments found!")
-        return []
-
-    # Sort by start time (should already be sorted, but just in case)
-    music_segs.sort(key=lambda x: x[0])
-
-    # Merge segments with gaps smaller than max_gap
-    merged = []
-    current_start, current_end = music_segs[0]
-
-    for start, end in music_segs[1:]:
-        if start - current_end <= max_gap:
-            # Extend current segment
-            current_end = max(current_end, end)
-        else:
-            # Save current segment and start new one
-            merged.append((current_start, current_end))
-            current_start, current_end = start, end
-
-    merged.append((current_start, current_end))
-
-    # Apply padding and minimum duration filter
-    results = []
-    idx = 1
-    for start, end in merged:
-        duration = end - start
-        if duration >= min_duration:
-            padded_start = max(0, start - padding)
-            padded_end = end + padding
-            results.append({
-                "index": idx,
-                "start": padded_start,
-                "end": padded_end,
-                "duration": padded_end - padded_start,
-                "original_start": start,
-                "original_end": end,
-            })
-            idx += 1
-
-    print(f"           Found {len(results)} singing segments after merge+filter:")
-    for seg in results:
-        print(f"           Song {seg['index']:2d}: "
-              f"{format_timecode(seg['start'])} → {format_timecode(seg['end'])} "
-              f"({seg['duration']:.0f}s)")
-
-    return results
-
-
-# ──────────────────────────────────────────────
-# Step 4: Export formats
-# ──────────────────────────────────────────────
-
-def export_edl(segments: list, output_path: str, fps: float = 29.97,
-               title: str = "Singing Segments", source_filename: str = None):
-    """
-    Export an EDL (Edit Decision List) file for DaVinci Resolve.
-    
-    DaVinci Resolve import: File → Import → Timeline → select the .edl file.
-    The EDL creates cut points at each singing segment's in/out points.
-    
-    Args:
-        source_filename: Original video filename (e.g. "stream_2026-04-01.mp4").
-                         Used as reel name + FROM CLIP NAME so DaVinci Resolve
-                         matches the EDL to the correct clip in the Media Pool.
-                         Without this, Resolve picks a random clip when multiple
-                         videos are loaded in the same project.
-    """
-    print(f"\n[Step 4/4] Exporting EDL: {output_path}")
-
-    # DaVinci Resolve uses both the reel name column AND the "* FROM CLIP NAME:"
-    # comment to identify which media clip an EDL edit refers to.
-    # 
-    # Reel name: traditionally 8 chars max, but Resolve accepts longer names.
-    #   We use the filename without extension, truncated to a safe length.
-    # FROM CLIP NAME: Resolve's preferred matching method. Must be the exact
-    #   filename (with extension) as it appears in the Media Pool.
-    
-    if source_filename:
-        clip_name = source_filename                          # full filename with extension
-        reel_name = Path(source_filename).stem[:32]          # stem, truncated for safety
-        # Replace spaces with underscores in reel name (some EDL parsers choke on spaces)
-        reel_name_safe = reel_name.replace(" ", "_")
-    else:
-        clip_name = None
-        reel_name_safe = "001"
-
-    # Calculate record timecodes: sequential placement on the output timeline
-    # Each segment is placed one after another, starting at 01:00:00:00
-    rec_offset = 3600.0  # start at 01:00:00:00
-
-    with open(output_path, "w", encoding="utf-8") as f:
-        f.write(f"TITLE: {title}\n")
-        f.write("FCM: NON-DROP FRAME\n\n")
-
-        current_rec_pos = rec_offset
-        for seg in segments:
-            edit_num = f"{seg['index']:03d}"
-            src_in = seconds_to_timecode(seg["start"], fps)
-            src_out = seconds_to_timecode(seg["end"], fps)
-            rec_in = seconds_to_timecode(current_rec_pos, fps)
-            rec_out = seconds_to_timecode(current_rec_pos + seg["duration"], fps)
-
-            # EDL format: edit# reel_name track_type transition src_in src_out rec_in rec_out
-            f.write(f"{edit_num}  {reel_name_safe}  V     C        {src_in} {src_out} {rec_in} {rec_out}\n")
-
-            # "* FROM CLIP NAME:" is the key line DaVinci uses for media matching.
-            # It must exactly match the clip name shown in the Media Pool.
-            if clip_name:
-                f.write(f"* FROM CLIP NAME: {clip_name}\n")
-
-            f.write(f"* COMMENT: Song {seg['index']} - Duration {seg['duration']:.0f}s\n\n")
-
-            current_rec_pos += seg["duration"]
-
-    print(f"           EDL file written with {len(segments)} edits")
-    if clip_name:
-        print(f"           Source clip name: {clip_name}")
-
-
-def export_csv(segments: list, output_path: str):
-    """Export singing segments as CSV for review or further processing."""
-    with open(output_path, "w", newline="", encoding="utf-8") as f:
-        writer = csv.writer(f)
-        writer.writerow(["index", "start_sec", "end_sec", "duration_sec",
-                         "start_timecode", "end_timecode"])
-        for seg in segments:
-            writer.writerow([
-                seg["index"],
-                f"{seg['start']:.2f}",
-                f"{seg['end']:.2f}",
-                f"{seg['duration']:.1f}",
-                format_timecode(seg["start"]),
-                format_timecode(seg["end"]),
-            ])
-    print(f"           CSV file written: {output_path}")
-
-
-def export_davinci_markers_csv(segments: list, output_path: str, fps: float = 29.97):
-    """
-    Export a CSV file that can be used with DaVinci Resolve's
-    'Import Markers from CSV' function (Resolve 18+).
-    
-    Format: #, Color, Name, Start TC, End TC, Duration TC, Notes
-    """
-    with open(output_path, "w", newline="", encoding="utf-8") as f:
-        writer = csv.writer(f)
-        # DaVinci Resolve Marker CSV header
-        writer.writerow(["#", "Color", "Name", "Start TC", "End TC", "Duration TC", "Notes"])
-        for seg in segments:
-            start_tc = seconds_to_timecode(seg["start"], fps)
-            end_tc = seconds_to_timecode(seg["end"], fps)
-            dur_tc = seconds_to_timecode(seg["duration"], fps)
-            writer.writerow([
-                seg["index"],
-                "Blue",
-                f"Song {seg['index']}",
-                start_tc,
-                end_tc,
-                dur_tc,
-                f"Duration: {seg['duration']:.0f}s",
-            ])
-    print(f"           DaVinci markers CSV written: {output_path}")
-
-
-def export_json(segments: list, output_path: str):
-    """Export as JSON for programmatic use."""
-    with open(output_path, "w", encoding="utf-8") as f:
-        json.dump(segments, f, indent=2, ensure_ascii=False)
-    print(f"           JSON file written: {output_path}")
-
-
-def export_ffmpeg_concat(segments: list, video_path: str, output_path: str):
-    """
-    Export a .bat/.sh script that uses ffmpeg to directly cut and
-    concatenate all singing segments into a single video file.
-    This is the fully automated option — no DaVinci needed.
-    """
-    video_name = Path(video_path).stem
-    ext = Path(video_path).suffix
-    out_video = str(Path(output_path).parent / f"{video_name}_singing_only{ext}")
-
-    is_windows = os.name == "nt" or sys.platform == "win32"
-    script_ext = ".bat" if is_windows else ".sh"
-    script_path = str(Path(output_path).with_suffix(script_ext))
-
-    lines = []
-    if is_windows:
-        lines.append("@echo off")
-        lines.append("REM Auto-generated ffmpeg script to extract singing segments")
-        lines.append(f'REM Source: {video_path}')
-        lines.append("")
-    else:
-        lines.append("#!/bin/bash")
-        lines.append("# Auto-generated ffmpeg script to extract singing segments")
-        lines.append(f'# Source: {video_path}')
-        lines.append("")
-
-    # Create a concat file list
-    concat_list_path = str(Path(output_path).parent / f"{video_name}_concat_list.txt")
-
-    # Generate individual segment extraction commands
-    segment_files = []
-    for seg in segments:
-        seg_file = f"_seg_{seg['index']:03d}{ext}"
-        seg_path = str(Path(output_path).parent / seg_file)
-        segment_files.append(seg_file)
-
-        start = seg["start"]
-        duration = seg["duration"]
-
-        cmd = (f'ffmpeg -y -ss {start:.2f} -i "{video_path}" '
-               f'-t {duration:.2f} -c copy "{seg_path}"')
-        lines.append(f"echo Extracting Song {seg['index']}...")
-        lines.append(cmd)
-        lines.append("")
-
-    # Generate concat list file
-    lines.append(f"echo Creating concat list...")
-    if is_windows:
-        lines.append(f'(')
-        for sf in segment_files:
-            seg_path = str(Path(output_path).parent / sf)
-            lines.append(f'  echo file \'{seg_path}\'')
-        lines.append(f') > "{concat_list_path}"')
-    else:
-        for i, sf in enumerate(segment_files):
-            seg_path = str(Path(output_path).parent / sf)
-            op = ">" if i == 0 else ">>"
-            lines.append(f"echo \"file '{seg_path}'\" {op} \"{concat_list_path}\"")
-
-    lines.append("")
-    lines.append(f"echo Concatenating all segments...")
-    lines.append(f'ffmpeg -y -f concat -safe 0 -i "{concat_list_path}" -c copy "{out_video}"')
-    lines.append("")
-
-    # Cleanup temp segment files
-    lines.append("echo Cleaning up temp files...")
-    for sf in segment_files:
-        seg_path = str(Path(output_path).parent / sf)
-        if is_windows:
-            lines.append(f'del "{seg_path}"')
-        else:
-            lines.append(f'rm -f "{seg_path}"')
-    if is_windows:
-        lines.append(f'del "{concat_list_path}"')
-    else:
-        lines.append(f'rm -f "{concat_list_path}"')
-
-    lines.append("")
-    lines.append(f'echo Done! Output: {out_video}')
-    if is_windows:
-        lines.append("pause")
-
-    with open(script_path, "w", encoding="utf-8") as f:
-        f.write("\n".join(lines))
-
-    if not is_windows:
-        os.chmod(script_path, 0o755)
-
-    print(f"           FFmpeg concat script written: {script_path}")
-    print(f"           Run it to auto-generate: {out_video}")
-
-
-# ──────────────────────────────────────────────
-# Export raw segmentation for debugging
-# ──────────────────────────────────────────────
-def export_raw_segments(segments: list, output_path: str):
-    """Export ALL raw segments (speech/music/noise) as CSV for debugging."""
-    with open(output_path, "w", newline="", encoding="utf-8") as f:
-        writer = csv.writer(f)
-        writer.writerow(["label", "start_sec", "end_sec", "duration_sec",
-                         "start_timecode", "end_timecode"])
-        for label, start, end in segments:
-            writer.writerow([
-                label,
-                f"{start:.2f}",
-                f"{end:.2f}",
-                f"{end - start:.1f}",
-                format_timecode(start),
-                format_timecode(end),
-            ])
-    print(f"           Raw segments CSV written: {output_path}")
-
-
-# ──────────────────────────────────────────────
-# Utility functions
-# ──────────────────────────────────────────────
-def format_timecode(seconds: float) -> str:
-    """Format seconds as HH:MM:SS."""
-    h = int(seconds // 3600)
-    m = int((seconds % 3600) // 60)
-    s = int(seconds % 60)
-    return f"{h:02d}:{m:02d}:{s:02d}"
-
-
-def seconds_to_timecode(seconds: float, fps: float = 29.97) -> str:
-    """Convert seconds to SMPTE timecode HH:MM:SS:FF."""
-    total_frames = int(seconds * fps)
-    ff = total_frames % int(round(fps))
-    total_seconds = total_frames // int(round(fps))
-    ss = total_seconds % 60
-    total_minutes = total_seconds // 60
-    mm = total_minutes % 60
-    hh = total_minutes // 60
-    return f"{hh:02d}:{mm:02d}:{ss:02d}:{ff:02d}"
-
-
-# ──────────────────────────────────────────────
-# Main
-# ──────────────────────────────────────────────
-def main():
-    parser = argparse.ArgumentParser(
-        description="Detect singing segments in stream recordings and export DaVinci Resolve markers.",
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-        epilog="""
-Examples:
-  python detect_singing.py "D:\\streams\\2026-04-04.mp4"
-  python detect_singing.py "D:\\streams\\2026-04-04.mp4" --gap 15 --min-duration 30
-  python detect_singing.py "D:\\streams\\2026-04-04.mp4" --output-dir "D:\\singing_edits"
-  python detect_singing.py "D:\\streams\\2026-04-04.mp4" --auto-cut
-
-Tips:
-  --gap 10      Merge music segments with <=10s gap (default). Increase if the singer
-                often pauses >10s between verses in the same song.
-  --min-duration 20  Ignore segments shorter than 20s (default). Decrease if
-                     the singer does very short songs or covers.
-  --padding 2   Add 2s padding before/after each segment (default). Helps catch
-                the very start/end of songs.
-  --auto-cut    Generate an ffmpeg script to automatically cut and concat all
-                singing segments into a single video file.
-  --fps 29.97   Frame rate for timecode calculation (default: 29.97 for NTSC).
-                Use 25 for PAL or 23.976 for film.
-        """,
-    )
-
-    parser.add_argument("video", help="Path to the stream recording video file")
-    parser.add_argument("--output-dir", "-o", default=None,
-                        help="Output directory (default: same directory as input video)")
-    parser.add_argument("--gap", "-g", type=float, default=10.0,
-                        help="Max gap (seconds) to merge nearby singing segments (default: 10)")
-    parser.add_argument("--min-duration", "-m", type=float, default=20.0,
-                        help="Minimum singing segment duration in seconds (default: 20)")
-    parser.add_argument("--padding", "-p", type=float, default=2.0,
-                        help="Padding (seconds) before/after each segment (default: 2)")
-    parser.add_argument("--fps", type=float, default=29.97,
-                        help="Video frame rate for timecode export (default: 29.97)")
-    parser.add_argument("--keep-wav", action="store_true",
-                        help="Keep the extracted WAV file (default: delete after processing)")
-    parser.add_argument("--auto-cut", action="store_true",
-                        help="Generate an ffmpeg script to auto-cut and concat singing segments")
-    parser.add_argument("--raw-segments", action="store_true",
-                        help="Also export all raw segments (speech/music/noise) as CSV")
-    parser.add_argument("--ffmpeg", default="ffmpeg",
-                        help="Path to ffmpeg binary (default: 'ffmpeg' from PATH)")
-
-    args = parser.parse_args()
-
-    # Validate input
-    video_path = os.path.abspath(args.video)
-    if not os.path.isfile(video_path):
-        print(f"[ERROR] Video file not found: {video_path}")
-        sys.exit(1)
-
-    # Set output directory
-    if args.output_dir:
-        output_dir = os.path.abspath(args.output_dir)
-        os.makedirs(output_dir, exist_ok=True)
-    else:
-        output_dir = os.path.dirname(video_path)
-
-    video_stem = Path(video_path).stem
-
-    print("=" * 60)
-    print("  Singing Segment Detector")
-    print("=" * 60)
-    print(f"  Input:        {video_path}")
-    print(f"  Output dir:   {output_dir}")
-    print(f"  Settings:     gap={args.gap}s, min={args.min_duration}s, pad={args.padding}s")
-    print(f"  FPS:          {args.fps}")
-
-    # Step 1: Extract audio
-    wav_path = os.path.join(output_dir, f"{video_stem}_audio.wav")
-    extract_audio(video_path, wav_path, ffmpeg_bin=args.ffmpeg)
-
-    # Step 2: Run segmentation
-    raw_segments = run_segmentation(wav_path)
-
-    # Step 3: Merge singing segments
-    singing_segments = merge_singing_segments(
-        raw_segments,
-        max_gap=args.gap,
-        min_duration=args.min_duration,
-        padding=args.padding,
-    )
-
-    if not singing_segments:
-        print("\n[RESULT] No singing segments detected. Try lowering --min-duration or increasing --gap.")
-        # Cleanup WAV
-        if not args.keep_wav and os.path.exists(wav_path):
-            os.remove(wav_path)
-        sys.exit(0)
-
-    # Step 4: Export results
-    edl_path = os.path.join(output_dir, f"{video_stem}_singing.edl")
-    csv_path = os.path.join(output_dir, f"{video_stem}_singing.csv")
-    markers_path = os.path.join(output_dir, f"{video_stem}_markers.csv")
-    json_path = os.path.join(output_dir, f"{video_stem}_singing.json")
-
-    export_edl(singing_segments, edl_path, fps=args.fps,
-               title=f"{video_stem} - Singing",
-               source_filename=Path(video_path).name)
-    export_csv(singing_segments, csv_path)
-    export_davinci_markers_csv(singing_segments, markers_path, fps=args.fps)
-    export_json(singing_segments, json_path)
-
-    if args.auto_cut:
-        export_ffmpeg_concat(singing_segments, video_path, json_path)
-
-    if args.raw_segments:
-        raw_csv_path = os.path.join(output_dir, f"{video_stem}_raw_segments.csv")
-        export_raw_segments(raw_segments, raw_csv_path)
-
-    # Cleanup WAV unless --keep-wav
-    if not args.keep_wav and os.path.exists(wav_path):
-        os.remove(wav_path)
-        print(f"\n           Temp WAV file deleted.")
-
-    # Summary
-    total_singing = sum(s["duration"] for s in singing_segments)
-    print("\n" + "=" * 60)
-    print("  DONE!")
-    print("=" * 60)
-    print(f"  Songs detected:       {len(singing_segments)}")
-    print(f"  Total singing time:   {format_timecode(total_singing)}")
-    print(f"  EDL file:             {edl_path}")
-    print(f"  DaVinci markers CSV:  {markers_path}")
-    print(f"  Segments CSV:         {csv_path}")
-    print(f"  Segments JSON:        {json_path}")
-    if args.auto_cut:
-        script_ext = ".bat" if (os.name == "nt" or sys.platform == "win32") else ".sh"
-        print(f"  Auto-cut script:      {json_path.replace('.json', script_ext)}")
-    print()
-    print("  To import into DaVinci Resolve:")
-    print("    Option A: File → Import → Timeline → select the .edl file")
-    print("    Option B: Timeline menu → Import Markers from CSV → select _markers.csv")
-    print("=" * 60)
-
-
-if __name__ == "__main__":
-    main()
diff --git a/ui/tab_detect.py b/ui/tab_detect.py
new file mode 100644
index 0000000..5b1d9bd
--- /dev/null
+++ b/ui/tab_detect.py
@@ -0,0 +1,505 @@
+"""
+Tab 2: Song Detection
+Detect singing segments in a video and export EDL/CSV/JSON for DaVinci Resolve.
+"""
+
+import os
+import threading
+import tkinter as tk
+from pathlib import Path
+from tkinter import filedialog, messagebox
+
+import customtkinter as ctk
+
+from core.fftools import find_tool, extract_audio
+from core.segmenter import check_segmenter_available, run_segmentation, merge_singing_segments, get_segment_stats
+from core.exporters import export_edl, export_csv, export_markers_csv, export_json, export_ffmpeg_script
+from utils.formats import format_timecode, fmt_dur, fmt_elapsed
+from ui.theme import BTN_NEUTRAL, ACCENT_PURPLE, ACCENT_GREEN
+
+
+class DetectTab:
+    """Song detection tab."""
+
+    VIDEO_EXTS = {".mp4", ".mov", ".mkv", ".avi", ".flv",
+                  ".ts", ".wmv", ".m4v", ".webm", ".mts", ".m2ts"}
+
+    def __init__(self, parent_frame, app):
+        self.frame = parent_frame
+        self.app = app
+        self.ffmpeg = app.ffmpeg
+
+        # State
+        self.input_path_var = tk.StringVar(value="")
+        self.output_dir_var = tk.StringVar(value="")
+        self.gap_var = tk.DoubleVar(value=10.0)
+        self.min_dur_var = tk.DoubleVar(value=20.0)
+        self.padding_var = tk.DoubleVar(value=2.0)
+        self.fps_var = tk.DoubleVar(value=29.97)
+        self.autocut_var = tk.BooleanVar(value=False)
+
+        self._running = False
+        self._stop_req = False
+
+        # Results
+        self._singing_segments = []
+        self._raw_segments = []
+
+        self._build_ui()
+        self._check_deps()
+
+    # ══════════════════════════════════════════════════════════════════════════
+    #  UI
+    # ══════════════════════════════════════════════════════════════════════════
+
+    def _build_ui(self):
+        scroll = ctk.CTkScrollableFrame(self.frame, corner_radius=12)
+        scroll.pack(fill="both", expand=True, padx=4, pady=4)
+
+        self._build_sec_input(scroll)
+        self._build_sec_params(scroll)
+        self._build_sec_run(scroll)
+        self._build_sec_results(scroll)
+
+    def _section(self, parent, title):
+        f = ctk.CTkFrame(parent, corner_radius=12)
+        hdr = ctk.CTkFrame(f, fg_color="transparent")
+        hdr.pack(fill="x", padx=14, pady=(10, 0))
+        ctk.CTkLabel(hdr, text=title,
+                     font=ctk.CTkFont(size=13, weight="bold")).pack(side="left")
+        ctk.CTkFrame(f, height=1, fg_color=("gray78", "gray32")).pack(
+            fill="x", padx=14, pady=(6, 0))
+        return f
+
+    # ── Input ─────────────────────────────────────────────────────────────────
+
+    def _build_sec_input(self, parent):
+        sec = self._section(parent, "1 · Input Video")
+        sec.pack(fill="x", pady=(0, 12))
+
+        body = ctk.CTkFrame(sec, fg_color="transparent")
+        body.pack(fill="x", padx=14, pady=(10, 4))
+
+        r1 = ctk.CTkFrame(body, fg_color="transparent")
+        r1.pack(fill="x", pady=(0, 4))
+        ctk.CTkLabel(r1, text="Video file:", width=96, anchor="w").pack(side="left")
+        ctk.CTkEntry(r1, textvariable=self.input_path_var).pack(side="left", fill="x", expand=True)
+        ctk.CTkButton(r1, text="Browse…", width=100, command=self._pick_input,
+                      **BTN_NEUTRAL).pack(side="left", padx=(8, 0))
+
+        # "Use Concat Output" button
+        self.use_concat_btn = ctk.CTkButton(
+            body, text="📎  Use Concat Output", width=200,
+            fg_color=ACCENT_PURPLE["fg"], text_color=ACCENT_PURPLE["text"],
+            hover_color=ACCENT_PURPLE["hover"],
+            command=self._use_concat_output)
+        self.use_concat_btn.pack(anchor="w", pady=(4, 4))
+
+        r2 = ctk.CTkFrame(body, fg_color="transparent")
+        r2.pack(fill="x", pady=(4, 0))
+        ctk.CTkLabel(r2, text="Output dir:", width=96, anchor="w").pack(side="left")
+        ctk.CTkEntry(r2, textvariable=self.output_dir_var).pack(side="left", fill="x", expand=True)
+        ctk.CTkButton(r2, text="Browse…", width=100, command=self._pick_output_dir,
+                      **BTN_NEUTRAL).pack(side="left", padx=(8, 0))
+
+        ctk.CTkLabel(sec, text="Output defaults to same directory as input video.",
+                     font=ctk.CTkFont(size=11), text_color=("gray50", "gray55")
+                     ).pack(anchor="w", padx=14, pady=(4, 10))
+
+    # ── Parameters ────────────────────────────────────────────────────────────
+
+    def _build_sec_params(self, parent):
+        sec = self._section(parent, "2 · Detection Parameters")
+        sec.pack(fill="x", pady=(0, 12))
+
+        body = ctk.CTkFrame(sec, fg_color="transparent")
+        body.pack(fill="x", padx=14, pady=(10, 10))
+
+        params = [
+            ("Merge gap (s):",     self.gap_var,     1, 60,  "Max silence between song parts to merge"),
+            ("Min duration (s):",  self.min_dur_var,  5, 120, "Ignore segments shorter than this"),
+            ("Padding (s):",       self.padding_var,  0, 15,  "Extra seconds before/after each song"),
+            ("FPS:",               self.fps_var,      23, 60, "Video frame rate for timecodes"),
+        ]
+
+        for label_text, var, lo, hi, tooltip in params:
+            row = ctk.CTkFrame(body, fg_color="transparent")
+            row.pack(fill="x", pady=3)
+
+            ctk.CTkLabel(row, text=label_text, width=130, anchor="w",
+                         font=ctk.CTkFont(size=12)).pack(side="left")
+
+            slider = ctk.CTkSlider(row, from_=lo, to=hi, variable=var,
+                                    width=200, number_of_steps=max(1, hi - lo))
+            slider.pack(side="left", padx=(0, 8))
+
+            val_lbl = ctk.CTkLabel(row, text=f"{var.get():.1f}", width=50, anchor="w",
+                                    font=ctk.CTkFont(size=12, weight="bold"))
+            val_lbl.pack(side="left")
+
+            ctk.CTkLabel(row, text=tooltip, font=ctk.CTkFont(size=11),
+                         text_color=("gray50", "gray55")).pack(side="left", padx=(10, 0))
+
+            # Update label on slider move
+            var.trace_add("write", lambda *_, v=var, l=val_lbl: l.configure(text=f"{v.get():.1f}"))
+
+        # Auto-cut checkbox
+        ctk.CTkCheckBox(body, text="Generate auto-cut ffmpeg script (no DaVinci needed)",
+                        variable=self.autocut_var).pack(anchor="w", pady=(8, 0))
+
+    # ── Run ───────────────────────────────────────────────────────────────────
+
+    def _build_sec_run(self, parent):
+        sec = self._section(parent, "3 · Detect")
+        sec.pack(fill="x", pady=(0, 12))
+
+        body = ctk.CTkFrame(sec, fg_color="transparent")
+        body.pack(fill="x", padx=14, pady=(12, 6))
+
+        btn_row = ctk.CTkFrame(body, fg_color="transparent")
+        btn_row.pack(fill="x", pady=(0, 10))
+
+        self.detect_btn = ctk.CTkButton(
+            btn_row, text="🎤  Start Detection", width=230, height=42,
+            font=ctk.CTkFont(size=14, weight="bold"),
+            fg_color=ACCENT_GREEN["fg"], hover_color=ACCENT_GREEN["hover"],
+            command=self.start_detect)
+        self.detect_btn.pack(side="left")
+
+        self.stop_btn = ctk.CTkButton(
+            btn_row, text="■  Stop", width=106, height=42,
+            fg_color=("gray80", "gray25"), text_color=("gray10", "gray90"),
+            hover_color=("#FCA5A5", "#7F1D1D"),
+            command=self._stop, state="disabled")
+        self.stop_btn.pack(side="left", padx=(12, 0))
+
+        # Dependency warning
+        self.dep_lbl = ctk.CTkLabel(body, text="", font=ctk.CTkFont(size=11),
+                                     text_color="#F97316", wraplength=600, anchor="w", justify="left")
+        self.dep_lbl.pack(fill="x", pady=(0, 4))
+
+        # Progress
+        self.progress = ctk.CTkProgressBar(body, height=16, corner_radius=8, mode="indeterminate")
+        self.progress.pack(fill="x", pady=(0, 6))
+        self.progress.stop()
+        self.progress.set(0)
+
+        self.status_lbl = ctk.CTkLabel(body, text="", anchor="w", font=ctk.CTkFont(size=12))
+        self.status_lbl.pack(fill="x")
+
+        ctk.CTkFrame(sec, height=6, fg_color="transparent").pack()
+
+    # ── Results ───────────────────────────────────────────────────────────────
+
+    def _build_sec_results(self, parent):
+        sec = self._section(parent, "4 · Results")
+        sec.pack(fill="x", pady=(0, 14))
+
+        self.results_body = ctk.CTkFrame(sec, fg_color="transparent")
+        self.results_body.pack(fill="x", padx=14, pady=(10, 10))
+
+        self.results_lbl = ctk.CTkLabel(
+            self.results_body, text="No results yet. Run detection first.",
+            font=ctk.CTkFont(size=12), text_color=("gray50", "gray55"))
+        self.results_lbl.pack(anchor="w")
+
+        # Song list (populated after detection)
+        self.song_list_frame = ctk.CTkFrame(self.results_body, fg_color="transparent")
+
+        # Export buttons (hidden until results)
+        self.export_frame = ctk.CTkFrame(sec, fg_color="transparent")
+
+    # ══════════════════════════════════════════════════════════════════════════
+    #  Logic
+    # ══════════════════════════════════════════════════════════════════════════
+
+    def _check_deps(self):
+        available, msg = check_segmenter_available()
+        if not available:
+            self.dep_lbl.configure(text=f"⚠  {msg}")
+            self.detect_btn.configure(state="disabled")
+        else:
+            self.dep_lbl.configure(text="")
+
+        if not self.ffmpeg:
+            self.dep_lbl.configure(text="⚠  ffmpeg not found. Install ffmpeg and add to PATH.")
+            self.detect_btn.configure(state="disabled")
+
+    def _pick_input(self):
+        f = filedialog.askopenfilename(
+            title="Select video file",
+            filetypes=[("Video files", "*.mp4 *.mov *.mkv *.avi *.flv *.ts *.wmv *.m4v *.webm *.mts"),
+                       ("All files", "*.*")])
+        if f:
+            self.input_path_var.set(f)
+            if not self.output_dir_var.get().strip():
+                self.output_dir_var.set(str(Path(f).parent))
+
+    def _pick_output_dir(self):
+        d = filedialog.askdirectory(title="Choose output folder")
+        if d:
+            self.output_dir_var.set(d)
+
+    def _use_concat_output(self):
+        """Fill input from the Concat tab's output path."""
+        if hasattr(self.app, 'concat_tab'):
+            path = self.app.concat_tab.get_last_output_path()
+            if path and Path(path).exists():
+                self.input_path_var.set(path)
+                if not self.output_dir_var.get().strip():
+                    self.output_dir_var.set(str(Path(path).parent))
+                self._set_status(f"Loaded concat output: {Path(path).name}")
+            elif path:
+                self.input_path_var.set(path)
+                if not self.output_dir_var.get().strip():
+                    self.output_dir_var.set(str(Path(path).parent))
+                self._set_status("Concat output path set (file not yet created — run concat first)")
+            else:
+                messagebox.showinfo("No output", "Set an output path in the Concat tab first.")
+
+    def _set_status(self, text, error=False):
+        color = "#DC2626" if error else ("gray10", "gray90")
+        self.status_lbl.configure(text=text, text_color=color)
+
+    def _stop(self):
+        self._stop_req = True
+        self._set_status("Stopping…")
+
+    def start_detect(self):
+        """Start the detection pipeline in a background thread."""
+        input_path = self.input_path_var.get().strip()
+        if not input_path:
+            messagebox.showerror("No input", "Select a video file first.")
+            return
+        if not os.path.isfile(input_path):
+            messagebox.showerror("File not found", f"Cannot find:\n{input_path}")
+            return
+
+        available, msg = check_segmenter_available()
+        if not available:
+            messagebox.showerror("Missing dependency", msg)
+            return
+
+        self._running = True
+        self._stop_req = False
+        self.detect_btn.configure(state="disabled")
+        self.stop_btn.configure(state="normal")
+        self.progress.configure(mode="indeterminate")
+        self.progress.start()
+        self._set_status("Starting detection…")
+
+        threading.Thread(target=self._detect_worker, args=(input_path,), daemon=True).start()
+
+    def _detect_worker(self, input_path):
+        output_dir = self.output_dir_var.get().strip() or str(Path(input_path).parent)
+        os.makedirs(output_dir, exist_ok=True)
+        stem = Path(input_path).stem
+
+        wav_path = os.path.join(output_dir, f"{stem}_audio.wav")
+
+        try:
+            # Step 1: Extract audio
+            def progress_cb(msg):
+                self.app.after(0, lambda: self._set_status(msg))
+
+            extract_audio(input_path, wav_path, self.ffmpeg, progress_cb=progress_cb)
+
+            if self._stop_req:
+                self._cleanup_and_finish(wav_path, "Stopped by user.")
+                return
+
+            # Step 2: Run segmentation
+            self.app.after(0, lambda: self._set_status("Running audio segmentation (this may take a while)…"))
+            raw_segments = run_segmentation(wav_path, progress_cb=progress_cb)
+
+            if self._stop_req:
+                self._cleanup_and_finish(wav_path, "Stopped by user.")
+                return
+
+            self._raw_segments = raw_segments
+
+            # Step 3: Merge
+            self.app.after(0, lambda: self._set_status("Merging singing segments…"))
+            singing = merge_singing_segments(
+                raw_segments,
+                max_gap=self.gap_var.get(),
+                min_duration=self.min_dur_var.get(),
+                padding=self.padding_var.get(),
+            )
+            self._singing_segments = singing
+
+            # Step 4: Export
+            if singing:
+                fps = self.fps_var.get()
+                source_name = Path(input_path).name
+
+                edl_path = os.path.join(output_dir, f"{stem}_singing.edl")
+                csv_path = os.path.join(output_dir, f"{stem}_singing.csv")
+                markers_path = os.path.join(output_dir, f"{stem}_markers.csv")
+                json_path = os.path.join(output_dir, f"{stem}_singing.json")
+
+                export_edl(singing, edl_path, fps=fps,
+                          title=f"{stem} - Singing", source_filename=source_name)
+                export_csv(singing, csv_path)
+                export_markers_csv(singing, markers_path, fps=fps)
+                export_json(singing, json_path)
+
+                if self.autocut_var.get():
+                    export_ffmpeg_script(singing, input_path, output_dir)
+
+                total_singing = sum(s["duration"] for s in singing)
+                result_msg = (f"✓  Found {len(singing)} songs  ·  "
+                              f"Total singing: {format_timecode(total_singing)}  ·  "
+                              f"Exported to: {output_dir}")
+
+                self.app.after(0, lambda: self._show_results(singing, edl_path, output_dir))
+            else:
+                result_msg = "No singing segments detected. Try lowering min duration or increasing gap."
+
+            # Cleanup WAV
+            if os.path.exists(wav_path):
+                os.remove(wav_path)
+
+            self.app.after(0, lambda: self._set_status(result_msg))
+
+        except Exception as e:
+            self.app.after(0, lambda: self._set_status(f"Error: {e}", error=True))
+            if os.path.exists(wav_path):
+                try:
+                    os.remove(wav_path)
+                except Exception:
+                    pass
+
+        self.app.after(0, self._finish_detect)
+
+    def _cleanup_and_finish(self, wav_path, msg):
+        if os.path.exists(wav_path):
+            try:
+                os.remove(wav_path)
+            except Exception:
+                pass
+        self.app.after(0, lambda: self._set_status(msg))
+        self.app.after(0, self._finish_detect)
+
+    def _finish_detect(self):
+        self._running = False
+        self._stop_req = False
+        self.detect_btn.configure(state="normal")
+        self.stop_btn.configure(state="disabled")
+        self.progress.stop()
+        self.progress.configure(mode="determinate")
+        self.progress.set(1.0 if self._singing_segments else 0)
+
+    def _show_results(self, segments, edl_path, output_dir):
+        """Display detection results in the Results section."""
+        # Clear previous
+        for w in self.song_list_frame.winfo_children():
+            w.destroy()
+        self.export_frame.pack_forget()
+
+        self.results_lbl.configure(
+            text=f"Found {len(segments)} singing segments:",
+            text_color=("gray10", "gray90"))
+
+        self.song_list_frame.pack(fill="x", pady=(8, 0))
+
+        # Header
+        hdr = ctk.CTkFrame(self.song_list_frame, fg_color=("gray88", "gray20"), corner_radius=8)
+        hdr.pack(fill="x", pady=(0, 4))
+        for text, w in [("#", 40), ("Start", 90), ("End", 90), ("Duration", 80)]:
+            ctk.CTkLabel(hdr, text=text, width=w, anchor="center",
+                         font=ctk.CTkFont(size=11, weight="bold")).pack(side="left", padx=4, pady=4)
+
+        # Rows
+        for seg in segments:
+            row = ctk.CTkFrame(self.song_list_frame, corner_radius=6, height=30)
+            row.pack(fill="x", pady=2)
+            row.pack_propagate(False)
+
+            vals = [
+                (f"Song {seg['index']}", 40),
+                (format_timecode(seg["start"]), 90),
+                (format_timecode(seg["end"]), 90),
+                (f"{seg['duration']:.0f}s", 80),
+            ]
+            for text, w in vals:
+                ctk.CTkLabel(row, text=text, width=w, anchor="center",
+                             font=ctk.CTkFont(size=11)).pack(side="left", padx=4)
+
+        # Total
+        total = sum(s["duration"] for s in segments)
+        ctk.CTkLabel(self.song_list_frame,
+                     text=f"Total singing time: {format_timecode(total)}",
+                     font=ctk.CTkFont(size=12, weight="bold")).pack(anchor="w", pady=(8, 0))
+
+        # Export info
+        self.export_frame.pack(fill="x", padx=14, pady=(4, 10))
+        for w in self.export_frame.winfo_children():
+            w.destroy()
+
+        ctk.CTkLabel(self.export_frame,
+                     text=f"Files exported to: {output_dir}",
+                     font=ctk.CTkFont(size=11), text_color=("gray45", "gray55"),
+                     wraplength=600, anchor="w", justify="left").pack(anchor="w")
+
+        info_lines = [
+            "• _singing.edl  →  DaVinci Resolve: File → Import → Timeline",
+            "• _markers.csv  →  DaVinci Resolve: Timeline → Import Markers from CSV",
+            "• _singing.csv  →  Human-readable segment list",
+            "• _singing.json →  Programmatic use",
+        ]
+        if self.autocut_var.get():
+            info_lines.append("• _autocut.bat  →  Run to auto-cut singing segments (no DaVinci needed)")
+
+        for line in info_lines:
+            ctk.CTkLabel(self.export_frame, text=line,
+                         font=ctk.CTkFont(size=11),
+                         text_color=("gray50", "gray55"), anchor="w").pack(anchor="w")
+
+    # ── Public API for Quick Flow ─────────────────────────────────────────────
+
+    def run_detect_headless(self, input_path: str, output_dir: str,
+                            gap: float, min_dur: float, padding: float,
+                            fps: float, autocut: bool,
+                            progress_cb=None) -> list:
+        """
+        Run detection synchronously (called from Quick Flow worker thread).
+        Returns list of singing segments.
+        """
+        os.makedirs(output_dir, exist_ok=True)
+        stem = Path(input_path).stem
+        wav_path = os.path.join(output_dir, f"{stem}_audio.wav")
+
+        try:
+            extract_audio(input_path, wav_path, self.ffmpeg, progress_cb=progress_cb)
+
+            raw_segments = run_segmentation(wav_path, progress_cb=progress_cb)
+
+            if progress_cb:
+                progress_cb("Merging singing segments…")
+
+            singing = merge_singing_segments(raw_segments,
+                                             max_gap=gap, min_duration=min_dur, padding=padding)
+
+            if singing:
+                source_name = Path(input_path).name
+                export_edl(singing, os.path.join(output_dir, f"{stem}_singing.edl"),
+                          fps=fps, title=f"{stem} - Singing", source_filename=source_name)
+                export_csv(singing, os.path.join(output_dir, f"{stem}_singing.csv"))
+                export_markers_csv(singing, os.path.join(output_dir, f"{stem}_markers.csv"), fps=fps)
+                export_json(singing, os.path.join(output_dir, f"{stem}_singing.json"))
+                if autocut:
+                    export_ffmpeg_script(singing, input_path, output_dir)
+
+            if os.path.exists(wav_path):
+                os.remove(wav_path)
+
+            return singing
+
+        except Exception:
+            if os.path.exists(wav_path):
+                try:
+                    os.remove(wav_path)
+                except Exception:
+                    pass
+            raise
diff --git a/ui/theme.py b/ui/theme.py
new file mode 100644
index 0000000..f317f0b
--- /dev/null
+++ b/ui/theme.py
@@ -0,0 +1,64 @@
+"""
+Theme, DPI, and shared styling constants.
+"""
+
+import sys
+
+# ── DPI awareness (call before any Tk/CTk window) ────────────────────────────
+def setup_dpi():
+    if sys.platform == "win32":
+        try:
+            import ctypes
+            ctypes.windll.shcore.SetProcessDpiAwareness(2)
+        except Exception:
+            try:
+                import ctypes
+                ctypes.windll.user32.SetProcessDPIAware()
+            except Exception:
+                pass
+
+
+def dpi_scale(widget) -> float:
+    try:
+        return max(1.0, widget.winfo_fpixels("1i") / 96.0)
+    except Exception:
+        return 1.0
+
+
+# ── Color accents ─────────────────────────────────────────────────────────────
+# Each feature area has its own accent color scheme: (light_mode, dark_mode)
+
+ACCENT_BLUE = {
+    "fg":    ("#3B82F6", "#2563EB"),
+    "hover": ("#2563EB", "#1D4ED8"),
+}
+
+ACCENT_PURPLE = {
+    "fg":       ("#EDE9FE", "#3B1F6E"),
+    "text":     ("#5B21B6", "#C4B5FD"),
+    "hover":    ("#DDD6FE", "#4C2889"),
+    "preview":  ("#7C3AED", "#A78BFA"),
+}
+
+ACCENT_GREEN = {
+    "fg":    ("#10B981", "#059669"),
+    "hover": ("#059669", "#047857"),
+}
+
+ACCENT_AMBER = {
+    "fg":    ("#F59E0B", "#D97706"),
+    "hover": ("#D97706", "#B45309"),
+}
+
+# Neutral button style
+BTN_NEUTRAL = {
+    "fg_color":    ("gray80", "gray25"),
+    "text_color":  ("gray10", "gray90"),
+    "hover_color": ("gray70", "gray35"),
+}
+
+BTN_SIDE = {
+    "fg_color":    ("gray82", "gray22"),
+    "text_color":  ("gray10", "gray90"),
+    "hover_color": ("gray72", "gray32"),
+}
diff --git a/utils/formats.py b/utils/formats.py
new file mode 100644
index 0000000..a5edc59
--- /dev/null
+++ b/utils/formats.py
@@ -0,0 +1,42 @@
+"""
+Timecode & duration formatting utilities.
+"""
+
+
+def fmt_dur(seconds: float) -> str:
+    """Format a duration as H:MM:SS or M:SS for display."""
+    if seconds < 0:
+        return "…"
+    if seconds == 0:
+        return "—"
+    s = int(round(seconds))
+    h, rem = divmod(s, 3600)
+    m, sec = divmod(rem, 60)
+    return f"{h}:{m:02d}:{sec:02d}" if h else f"{m}:{sec:02d}"
+
+
+def fmt_elapsed(s: float) -> str:
+    if s < 60:
+        return f"{int(s)}s"
+    m, sec = divmod(int(s), 60)
+    return f"{m}m {sec:02d}s"
+
+
+def format_timecode(seconds: float) -> str:
+    """Format seconds as HH:MM:SS."""
+    h = int(seconds // 3600)
+    m = int((seconds % 3600) // 60)
+    s = int(seconds % 60)
+    return f"{h:02d}:{m:02d}:{s:02d}"
+
+
+def seconds_to_smpte(seconds: float, fps: float = 29.97) -> str:
+    """Convert seconds to SMPTE timecode HH:MM:SS:FF."""
+    total_frames = int(seconds * fps)
+    ff = total_frames % int(round(fps))
+    total_seconds = total_frames // int(round(fps))
+    ss = total_seconds % 60
+    total_minutes = total_seconds // 60
+    mm = total_minutes % 60
+    hh = total_minutes // 60
+    return f"{hh:02d}:{mm:02d}:{ss:02d}:{ff:02d}"