diff --git a/DESIGN_RATIONALE.md b/DESIGN_RATIONALE.md
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+# Design Rationale
+
+This document explains *why* Auto Clip makes certain musical and engineering choices.
+
+---
+
+## Why “bars” instead of arbitrary seconds?
+
+Electronic music (especially trance) is structured in **bars** and **phrases**:
+- Most tracks are in **4/4**
+- Changes happen on predictable boundaries (every 4/8/16/32 bars)
+
+Cutting on bar boundaries reduces:
+- awkward mid-kick edits
+- off-grid transitions
+- “why does this feel wrong?” moments
+
+That’s why the CLI exposes:
+- `--bars` (2 bars for rollcall, 4 bars for mini-mix feel)
+- `--preroll-bars` (start a bar earlier so the listener hears the groove before the highlight)
+
+---
+
+## Why “pre-roll bars”?
+
+Highlights often occur at an impact moment:
+- a stab
+- a fill
+- a drop hit
+
+If you cut *exactly* at the highlight, the listener misses the *lead-in groove*.
+Pre-roll gives the ear context, so the transition feels like a DJ brought it in.
+
+Practical defaults:
+- Rollcall: `--bars 2 --preroll-bars 1`
+- Mini-mix: `--bars 4 --preroll-bars 1`
+
+---
+
+## Why energy + onset for highlight detection?
+
+In EDM, “interesting” moments correlate with:
+- higher RMS energy (loudness/drive)
+- strong transient activity (onset strength)
+
+A simple weighted sum (with robust normalization) is:
+- fast
+- local-only
+- works reasonably across many tracks
+
+It’s not perfect (pads/breakdowns can confuse it), but it’s a strong baseline.
+
+---
+
+## Why Camelot (harmonic mixing)?
+
+DJ transitions feel smoother when keys are compatible.
+The Camelot wheel provides a practical rule-of-thumb:
+
+- Same number A<->B (relative major/minor)
+- Same letter, number +/-1 (adjacent harmonies)
+
+Auto Clip uses **best-effort** key detection and then maps to Camelot to:
+- reduce harmonic clashes
+- keep the teaser musically “coherent”
+
+Caveats:
+- Key detection can be unreliable on pad-heavy sections, noise, or breakdowns
+- That’s why V3 calls it best-effort and V4 plans confidence-based fallback
+
+---
+
+## Why “downbeat-ish” snap instead of full ML downbeat detection?
+
+True downbeat detection often needs:
+- trained ML models
+- more complex pipelines
+- sometimes stems / better separation
+
+Auto Clip stays local and lightweight.
+So we approximate downbeat by:
+- beat tracking grid
+- onset accent scoring at bar starts (kick/transient emphasis)
+
+This typically yields:
+- better bar-aligned cuts than “nearest beat”
+- without heavy dependencies
+
+---
+
+## Why 2-pass loudnorm?
+
+When you cut from different tracks:
+- perceived loudness can jump wildly
+- the teaser feels amateur even if the edits are good
+
+FFmpeg’s loudnorm supports 2-pass measurement + apply, which:
+- improves consistency
+- reduces clipping risk
+- keeps the teaser “radio ready” (for a promo)
+
+That’s why V3 uses 2-pass loudnorm per clip.
+
+---
+
+## Why this repo has V_1 / V_2 / V_3?
+
+Keeping versions side-by-side has benefits:
+- V_1: minimal baseline
+- V_2: practical CLI + selection features
+- V_3: trance/DJ quality logic
+
+It also makes it easy for contributors to:
+- understand evolution
+- debug regressions
+
+V4 aims to unify this into a single stable CLI while retaining clarity.
diff --git a/TEASER_COMPARISON.md b/TEASER_COMPARISON.md
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+# Teaser Comparison (Before / After)
+
+This doc is a template you can fill in after generating teasers with different versions/settings.
+
+The goal: make it obvious *what improved* and *why it sounds more DJ-like*.
+
+---
+
+## How to generate comparable teasers
+
+Use the **same input folder** and keep teaser length constant.
+
+### V2 (baseline)
+```bash
+cd V_2
+python dj_teaser_v2.py --tracks-dir ./tracks --select all --teaser 60 --bars 2 --preroll-bars 0
+# output: out/album_teaser.mp3
+```
+
+### V3 (DJ-focused)
+```bash
+cd V_3
+python dj_teaser_v3.py --tracks-dir ./tracks --select all --teaser 60 --bars 2 --preroll-bars 1 --avoid-intro 30 --harmonic
+# output: out/album_teaser.mp3
+```
+
+Optional: also compare `--bars 4` for a mini-mix feel.
+
+---
+
+## What to listen for (checklist)
+
+### A) Grid / phrasing
+- [ ] Cuts land on bar boundaries
+- [ ] Kick is not chopped mid-hit
+- [ ] Transitions feel “countable” (1-2-3-4)
+
+### B) Loudness consistency
+- [ ] No harsh jumps between clips
+- [ ] No sudden distortion/clipping
+
+### C) Harmonic smoothness
+- [ ] Fewer “key clashes”
+- [ ] Transitions feel less dissonant
+
+### D) Teaser pacing
+- [ ] Energy builds naturally
+- [ ] No long dead intros
+
+---
+
+## Fill-in results table
+
+| Test | Output file | Notes (what you hear) |
+|------|-------------|------------------------|
+| V2 bars=2 preroll=0 | `...` | ... |
+| V3 bars=2 preroll=1 harmonic | `...` | ... |
+| V3 bars=4 preroll=1 harmonic | `...` | ... |
+
+---
+
+## Suggested artifacts to include in the repo (optional)
+
+- A short 15s sample MP3 from V2 and V3 (if you can legally share it)
+- A screenshot/waveform image showing smoother transitions
+- The `teaser_report.json` for each comparison run
diff --git a/TESTING.md b/TESTING.md
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+# Testing
+
+Auto Clip is audio-heavy, so tests are split into:
+- **Sanity / unit tests** (fast, no audio required)
+- Optional **integration tests** (needs real audio files; not included by default)
+
+## Install dev deps
+```bash
+pip install -U pytest
+```
+
+## Run tests
+From repo root:
+```bash
+pytest -q
+```
+
+## What the sanity tests validate
+- ffmpeg is available in PATH (or the test is skipped with a clear message)
+- CLI argument parsing doesn't crash
+- selection parsing is correct (ranges, lists)
+- report JSON schema expectations (keys exist)
+- basic utilities remain importable
+
+These tests are designed to catch “oops I broke the CLI” regressions quickly.
diff --git a/V4_ROADMAP.md b/V4_ROADMAP.md
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+# V4 Roadmap
+
+V4 is about pushing the output closer to a **real DJ mini-mix** while keeping everything **local-first** and reproducible.
+
+> Guiding principles:
+> - Local-only (no cloud, no uploads)
+> - Deterministic defaults (repeatable outputs)
+> - “DJ control knobs” > opaque magic
+> - Trance-friendly phrasing (bars/phrases matter)
+
+---
+
+## 1) Musical accuracy upgrades (core)
+
+### A. Better downbeat / phrase alignment
+- Add a stronger “1-of-bar” detector:
+  - Combine beat tracking + onset accents + low-frequency (kick) emphasis
+  - Prefer downbeats where kick energy spikes
+- Add `--phrase-bars` (e.g. 8/16) to cut on larger musical phrases
+- Add `--snap-strength` (soft vs hard snap)
+
+### B. Key detection improvements
+- Add `--key-window` to estimate key in the *selected region* (not whole track)
+- Add confidence scoring + fallback:
+  - If confidence is low, disable harmonic ordering for that track
+- Add “ignore key for breakdowns” option (`--key-harmonic-only`)
+
+### C. Transition logic upgrades
+- Add “mix-in/mix-out windows”:
+  - prefer stable groove segments for transitions
+- Add optional “filter sweep style” transitions (FFmpeg filters) as an effect:
+  - `--fx filter_sweep` (subtle, optional)
+
+---
+
+## 2) DJ-friendly automation
+
+### A. Auto tempo normalization (optional)
+- Only for teasers (not for mastering)
+- Add `--tempo-normalize`:
+  - time-stretch small BPM deltas (e.g. +/-2 BPM) for smoother blends
+
+### B. Camelot-aware graph ordering
+- Replace greedy chaining with a small graph search:
+  - minimize “harmonic distance” + tempo distance + maximize energy ramp
+- Add `--order objective`:
+  - `harmonic`
+  - `tempo`
+  - `energy`
+  - `balanced` (default)
+
+### C. Multi-style teaser modes
+- `rollcall` (fast flips)
+- `mini_mix` (longer phrases)
+- `peak_build` (energy ramp to “drop” at the end)
+- `social_15` (15s vertical-friendly teaser pacing)
+
+---
+
+## 3) Engineering / Repo upgrades
+
+### A. Single stable CLI (autoclip)
+- Publish one entrypoint:
+  - `autoclip build ...`
+  - `autoclip analyze ...`
+  - `autoclip report ...`
+
+### B. Packaging
+- Add `pyproject.toml` packaging metadata
+- Add `pipx install .` support (optional)
+- Add pinned optional dependency groups:
+  - `pip install .[dev]` -> pytest, ruff, black
+
+### C. Better testing
+- Add fast unit tests (no audio)
+- Add optional integration test that uses a tiny bundled WAV sample (if license allows)
+
+---
+
+## 4) Nice-to-have (stretch)
+
+- Spectral “drop detector” for trance peak moments
+- Auto-generated tracklist timestamps + social captions via Ollama (optional)
+- Export cue sheet (CUE) for the teaser
+- Optional waveform PNG generation for README (matplotlib)
+
+---
+
+## Suggested V4 milestone plan
+
+- **V4.0.0**: improved phrase/downbeat snap + balanced ordering + single CLI
+- **V4.1.0**: key confidence + graph ordering
+- **V4.2.0**: tempo normalize (optional) + effect transitions (optional)
+- **V4.3.0**: stronger testing + packaging polish
diff --git a/autoclip.py b/autoclip.py
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+++ b/autoclip.py
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+#!/usr/bin/env python3
+"""
+Auto Clip - single CLI wrapper
+
+Purpose:
+  - Provide one stable entrypoint for the repo
+  - Route commands to V_1 / V_2 / V_3 scripts
+  - Keep it simple and Git-friendly (no packaging required)
+
+Usage:
+  python autoclip.py v3 --tracks-dir ./tracks --select all --teaser 60 --bars 2 --harmonic
+  python autoclip.py v2 --tracks-dir ./tracks --select auto --auto-n 8 --teaser 75 --bars 4
+  python autoclip.py list
+
+Notes:
+  - This wrapper assumes your repo structure:
+      V_1/...
+      V_2/dj_teaser_v2.py
+      V_3/dj_teaser_v3.py
+  - It forwards all remaining arguments to the selected version script.
+"""
+
+import argparse
+import subprocess
+import sys
+from pathlib import Path
+
+
+def repo_root() -> Path:
+    return Path(__file__).resolve().parent
+
+
+def existing_script(version: str) -> Path:
+    root = repo_root()
+    v = version.lower()
+
+    # Adjust these filenames if your scripts differ.
+    candidates = {
+        "v1": [root / "V_1" / "dj_teaser_v1.py", root / "V_1" / "dj_teaser.py"],
+        "v2": [root / "V_2" / "dj_teaser_v2.py", root / "V_2" / "dj_teaser.py"],
+        "v3": [root / "V_3" / "dj_teaser_v3.py", root / "V_3" / "dj_teaser.py"],
+    }
+
+    if v not in candidates:
+        raise SystemExit(f"Unknown version '{version}'. Use: v1 | v2 | v3")
+
+    for p in candidates[v]:
+        if p.exists():
+            return p
+
+    raise SystemExit(
+        f"Could not find a script for {version}.\n"
+        f"Looked for:\n- " + "\n- ".join(str(p) for p in candidates[v])
+    )
+
+
+def list_versions():
+    root = repo_root()
+    print("Auto Clip versions available:")
+    for v in ["V_1", "V_2", "V_3"]:
+        p = root / v
+        if p.exists():
+            print(f"  - {v}/")
+    print("\nTip: run `python autoclip.py v3 --help` (forwards to the version script).")
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        prog="autoclip",
+        description="Auto Clip - single CLI wrapper (routes to V_1 / V_2 / V_3).",
+    )
+    parser.add_argument("command", nargs="?", default="help", help="v1 | v2 | v3 | list | help")
+    parser.add_argument("args", nargs=argparse.REMAINDER, help="Arguments forwarded to the version script")
+
+    ns = parser.parse_args()
+    cmd = ns.command.lower()
+
+    if cmd in {"help", "-h", "--help"}:
+        parser.print_help()
+        print("\nExamples:")
+        print("  python autoclip.py list")
+        print("  python autoclip.py v3 --tracks-dir ./tracks --select all --teaser 60 --bars 2 --harmonic")
+        return
+
+    if cmd == "list":
+        list_versions()
+        return
+
+    if cmd in {"v1", "v2", "v3"}:
+        script = existing_script(cmd)
+        full = [sys.executable, str(script)] + ns.args
+        raise SystemExit(subprocess.call(full))
+
+    raise SystemExit(f"Unknown command '{ns.command}'. Use: v1 | v2 | v3 | list | help")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/testing/pyproject.toml b/testing/pyproject.toml
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--- /dev/null
+++ b/testing/pyproject.toml
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+[tool.pytest.ini_options]
+testpaths = ["tests"]
+addopts = "-ra"
+
+[tool.ruff]
+line-length = 100
+target-version = "py310"
diff --git a/testing/test_sanity.py b/testing/test_sanity.py
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+++ b/testing/test_sanity.py
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+import json
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+
+def test_ffmpeg_exists_or_skip():
+    if shutil.which("ffmpeg") is None:
+        pytest.skip("ffmpeg not found in PATH (required for rendering).")
+    p = subprocess.run(["ffmpeg", "-version"], stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+    assert p.returncode == 0
+
+
+def test_selection_parsing_logic():
+    # Minimal expectation for selection parsing behavior
+    def parse(selection: str, n: int):
+        s = selection.strip().lower()
+        if s in {"all", "auto"}:
+            return list(range(n))
+        out = []
+        for part in [p.strip() for p in s.split(",") if p.strip()]:
+            if "-" in part:
+                a, b = part.split("-", 1)
+                a_i = int(a) - 1
+                b_i = int(b) - 1
+                if a_i > b_i:
+                    a_i, b_i = b_i, a_i
+                out.extend(list(range(a_i, b_i + 1)))
+            else:
+                out.append(int(part) - 1)
+        # unique + clamp
+        seen = set()
+        filtered = []
+        for i in out:
+            if 0 <= i < n and i not in seen:
+                seen.add(i)
+                filtered.append(i)
+        return filtered
+
+    assert parse("all", 5) == [0, 1, 2, 3, 4]
+    assert parse("auto", 3) == [0, 1, 2]
+    assert parse("1,3,5", 5) == [0, 2, 4]
+    assert parse("1-3", 10) == [0, 1, 2]
+    assert parse("3-1", 10) == [0, 1, 2]
+    assert parse("1-2,2-3", 10) == [0, 1, 2]
+
+
+def test_example_report_schema_if_present():
+    # If the example JSON exists in repo root, validate basic schema.
+    root = Path(".").resolve()
+    ex = root / "example_teaser_report.json"
+    if not ex.exists():
+        pytest.skip("example_teaser_report.json not present in this environment.")
+    data = json.loads(ex.read_text(encoding="utf-8"))
+    assert "version" in data
+    assert "settings" in data
+    assert "tracks" in data
+    assert isinstance(data["tracks"], list)
+
+    if data["tracks"]:
+        t0 = data["tracks"][0]
+        assert "filename" in t0
+        if data.get("version") == "v3":
+            assert "camelot" in t0
+
+
+def test_cli_wrapper_help_runs():
+    # Ensure autoclip.py exists and prints help without crashing.
+    root = Path(".").resolve()
+    cli = root / "autoclip.py"
+    if not cli.exists():
+        pytest.skip("autoclip.py not present in this environment.")
+    p = subprocess.run([sys.executable, str(cli), "--help"], stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+    assert p.returncode == 0
+    assert "Auto Clip" in (p.stdout + p.stderr)