feat: SDD workflow — test sync, song generation + validation, ReaScript hybrid pipeline

- compose-test-sync: fix 3 failing tests (NOTE_TO_MIDI, DrumLoopAnalyzer mock, section name)
- generate-song: CLI wrapper + RPP validator (6 structural checks) + 4 e2e tests
- reascript-hybrid: ReaScriptGenerator + command protocol + CLI + 16 unit tests
- 110/110 tests passing
- Full SDD cycle (propose→spec→design→tasks→apply→verify) for all 3 changes

tests/test_generate_song.py

@@ -0,0 +1,97 @@
+"""Tests for scripts/generate.py — E2E song generation and RPP validator."""
+
+from __future__ import annotations
+
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).parents[1]))
+
+
+class TestGenerateCLI:
+    """Smoke and integration tests for the generate.py CLI."""
+
+    def test_generate_cli_smoke(self, tmp_path):
+        """CLI produces a non-empty .rpp file at the expected path."""
+        output = tmp_path / "song.rpp"
+        result = subprocess.run(
+            [
+                sys.executable,
+                "scripts/generate.py",
+                "--bpm", "95",
+                "--key", "Am",
+                "--output", str(output),
+                "--seed", "42",
+            ],
+            capture_output=True,
+            text=True,
+            timeout=60,
+        )
+        assert result.returncode == 0, f"stderr: {result.stderr}"
+        assert output.exists(), f"File not created: {output}"
+        assert output.stat().st_size > 0, "File is empty"
+
+    def test_validate_passes_for_valid_output(self, tmp_path):
+        """With --validate, CLI returns 0 when validator sees no errors."""
+        output = tmp_path / "song.rpp"
+        result = subprocess.run(
+            [
+                sys.executable,
+                "scripts/generate.py",
+                "--bpm", "95",
+                "--key", "Am",
+                "--output", str(output),
+                "--seed", "42",
+                "--validate",
+            ],
+            capture_output=True,
+            text=True,
+            timeout=60,
+        )
+        assert result.returncode == 0, f"stderr: {result.stderr}\nstdout: {result.stdout}"
+
+    def test_validate_detects_track_count_violation(self, tmp_path):
+        """Validator flags a project with fewer than 9 tracks."""
+        from src.validator.rpp_validator import validate_rpp_output
+
+        rpp_path = tmp_path / "bad.rpp"
+        # Write a minimal .rpp with only 5 <TRACK> blocks
+        content = (
+            "<REAPER_PROJECT 0.1 \"7.65/win64\" 0 0\n"
+            + "  <TRACK\n  NAME \"t1\"\n>\n"
+            + "  <TRACK\n  NAME \"t2\"\n>\n"
+            + "  <TRACK\n  NAME \"t3\"\n>\n"
+            + "  <TRACK\n  NAME \"t4\"\n>\n"
+            + "  <TRACK\n  NAME \"t5\"\n>\n"
+            + ">"
+        )
+        rpp_path.write_text(content, encoding="utf-8")
+        errors = validate_rpp_output(str(rpp_path))
+        assert any("Expected 9" in e for e in errors), f"Got: {errors}"
+
+    def test_reproducibility_same_seed(self, tmp_path):
+        """Two runs with the same seed produce byte-identical output."""
+        output_a = tmp_path / "song_a.rpp"
+        output_b = tmp_path / "song_b.rpp"
+        for out_path in (output_a, output_b):
+            result = subprocess.run(
+                [
+                    sys.executable,
+                    "scripts/generate.py",
+                    "--bpm", "95",
+                    "--key", "Am",
+                    "--output", str(out_path),
+                    "--seed", "42",
+                ],
+                capture_output=True,
+                text=True,
+                timeout=60,
+            )
+            assert result.returncode == 0, f"stderr: {result.stderr}"
+
+        assert output_a.read_bytes() == output_b.read_bytes(), (
+            "Outputs differ — seed does not guarantee reproducibility"
+        )