Public-ready: JSON tune specs, first-class loop API, licence, AGENTS.md

- MidiFile.set_loop(): one call writes LOOP_START/END, RPR LOOP
  START/END (Reaper) and LoopBegin/End markers - every engine finds
  its dialect; reader now parses markers and the smoke test asserts
  the round-trip
- tools/make_tune.py: declarative JSON spec -> fully arranged MIDI
  with style presets (dos_adventure, n64_ambient, chiptune_racing);
  the agent-friendly front door, no Python required
- tunes/specs/: demo tune 04 'Tea Break at the Terminal' (Am/112,
  loop bars 4-20) generated entirely from JSON
- AGENTS.md: spec schema, score grammar, verification loop, looping
  conventions for game BGM
- MIT LICENSE; history audited clean of credentials

AGENTS.md

@@ -0,0 +1,83 @@
+# Notes for AI agents
+
+This repo is designed to be driven by agents. Everything is deterministic,
+self-verifying, and dependency-light.
+
+## Fastest path: generate a tune from a JSON spec
+
+```bash
+python3 tools/make_tune.py tunes/specs/04_tea_break_at_the_terminal.json --render
+```
+
+Copy that spec, change `name`, `bpm`, `key`, `chords`, `melody`, `loop`.
+The style preset (`dos_adventure`, `n64_ambient`, `chiptune_racing`) handles
+arrangement: instruments, accompaniment patterns, drums, vibrato, mix levels.
+You supply the music theory: a per-bar chord chart and a melody.
+
+## Spec schema
+
+```jsonc
+{
+  "name": "file_name_no_extension",
+  "style": "dos_adventure | n64_ambient | chiptune_racing",
+  "bpm": 112,
+  "key": ["A", "minor"],            // "major" or "minor"
+  "chords": [["A","m"], ["F",""], ...],   // one per bar; qualities:
+                                         // maj m dim aug 7 maj7 m7 m7b5 6 m6 9 add9 sus2 sus4 sus
+  "melody_start_bar": 4,
+  "melody": "A4-8 C5-8 E5-4 A5-2 | ...",  // see score grammar below
+  "loop": {"start_bar": 4, "end_bar": 20}, // optional; writes LOOP_START/END,
+                                           // RPR LOOP START/END, LoopBegin/End markers
+  "counter": "...",                 // optional 2nd line (dos_adventure only)
+  "fills_at": [11, 19]              // optional drum-fill bars (styles with drums)
+}
+```
+
+## Score grammar (melody strings)
+
+- Tokens: `PITCH-dur-vel` — `A4-8-90` (A4 eighth, vel 90). Durations:
+  `1` whole, `2` half, `4` quarter (default), `8` eighth, `16` sixteenth.
+- Rests: `r4`, `r8`, `r16`, `r2`, `r1`.
+- `|` separates bars. **If you use `|`, every bar must total exactly 4/4**
+  — the parser raises `ValueError: bar N totals X ticks` and tells you which
+  bar is wrong. Use it; it is the single most useful bug-catcher here.
+- Pitches: letter + optional `#`/`b` + octave, e.g. `Bb3`, `F#5`.
+
+## Verification loop (do this, don't skip it)
+
+1. `python3 tools/make_tune.py spec.json --render` — writes MIDI, re-parses
+   it, renders WAV, checks for clipping / dead air / wrong duration.
+2. If a check fails, fix the spec and re-run. Never declare success without
+   a passing run.
+3. Optional theory audit: parse the lead track with `midikit.read()`, flag
+   notes outside the key scale and outside the current bar's chord tones,
+   and treat each flag as either intentional colour or a bug.
+
+## Looping for game background music
+
+`loop` in the spec (or `MidiFile.set_loop(start_tick, end_tick)` in Python)
+writes markers in three conventions so any engine/DAW finds them:
+`LOOP_START/LOOP_END`, `RPR LOOP START/RPR LOOP END` (Reaper),
+`LoopBegin/LoopEnd`. Convention: intro bars sit *before* the loop start so
+the engine plays the intro once, then jumps back to loop start and returns
+to loop end.
+
+## Library use (Python)
+
+`lib/midikit.py` and `lib/songkit.py` are stdlib-only — drop them into any
+project. Key entry points: `MidiFile`, `Track`, `MPQN.from_bpm`,
+`set_loop`, `verify`; songkit: `bar`, `melody`, `arp`, `bass_drive`,
+`drums`, `vibrato`, `parse_score`. Times are ticks; `bar(n)` converts bars
+to ticks at 480 tpq.
+
+## Rendering
+
+Needs `timidity` + a GM soundfont (e.g. FluidR3_GM.sf2, not bundled —
+licensing). Debian's timidity: use `-Ow -s 44` (no `-O2` mode).
+
+## Known gotchas
+
+- Pitch bends extend file duration (vibrato tails count).
+- No comments inside melody strings — `#` gets parsed as a note.
+- GM2 patches (ocarina etc.) are unreliable on GM1 synths; use pan flute.
+- Five hot tracks sum to clipping; lower CC7 volumes, not velocities.

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Kevin Hermes (an AI agent) and Steve Calcott
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -16,34 +16,58 @@ hand-edited hex. If a tune is wrong, you fix a bar of text and rebuild.
 | 01 | Service Station at 2 AM | DOS adventure main theme (LucasArts-meets-OPL) | Dm / 132 | ~58s |
 | 02 | Kestrel Over The Fens | N64 ambient exploration theme | G / 72 | ~82s |
 | 03 | The U's Late Equaliser | chiptune sports/racing theme | Em / 152 | ~44s |
+| 04 | Tea Break at the Terminal | DOS puzzle-game theme (from JSON spec) | Am / 112 | ~51s |
 
 All files are Standard MIDI File **format 1**, 480 tpq, General MIDI
-instruments, with `LOOP_START` / `LOOP_END` markers so a game engine can
-skip the intro and loop the gameplay section.
+instruments, with loop markers (`LOOP_START/END`, `RPR LOOP START/END`,
+`LoopBegin/End`) so a game engine can skip the intro and loop the
+gameplay section. See [Looping](#looping) below.
 
 ## Quick start
 
 ```bash
 ./tools/build_all.sh          # regenerate, verify, render WAVs, audio checks
 python3 tests/smoke_test.py   # library self-test
+python3 tools/make_tune.py tunes/specs/04_tea_break_at_the_terminal.json --render
 ```
 
 Rendering needs `timidity` + a GM soundfont (`FluidR3_GM.sf2`). Note:
 Debian's timidity build has no `-O2` mode — use `-Ow -s 44`.
 
+**AI agents**: see [AGENTS.md](AGENTS.md) — the JSON spec format is the
+agent-friendly front door; no Python required to make a tune.
+
 ## Layout
 
 ```
 lib/midikit.py      SMF writer + reader/verifier (stdlib only)
 lib/songkit.py      composition helpers: bar grids, OPL arps, vibrato, drums
 tunes/*.py          one script per tune; each self-verifies on run
+tunes/specs/*.json  declarative tune specs -> tools/make_tune.py
 tools/build_all.sh  full pipeline: generate -> verify -> render -> check
+tools/make_tune.py  JSON spec -> fully arranged MIDI (style presets)
 tools/check_wav.py  WAV sanity: clipping, loudness, dead air
 tests/smoke_test.py library round-trip test (cross-checked with mido)
 midi/               generated .mid files
 archive/            the April 2026 wreckage (70-byte "working" MIDIs, rest in peace)
 ```
 
+## Looping
+
+Game background music convention: the intro bars play once, then the
+engine jumps back to the loop point. Declare it once and every marker
+dialect gets written:
+
+```python
+mf.set_loop(bar(4), bar(28))   # Python
+```
+```json
+"loop": {"start_bar": 4, "end_bar": 20}   // JSON spec
+```
+
+Markers written: `LOOP_START/LOOP_END` (ours), `RPR LOOP START/END`
+(Reaper), `LoopBegin/LoopEnd` (various engines/trackers).
+
 ## Composing a new tune
 
 Copy a tune script. Melodies are written as bar grids:
@@ -79,3 +103,8 @@ on a peak of 32767.
   (trailing bends/resets), but "Notes lost totally" is not.
 - A bar-length linter in the score parser catches more composition bugs
   than any amount of staring at note lists.
+
+## Licence
+
+MIT — see [LICENSE](LICENSE). Soundfonts are not bundled (licensing);
+install FluidR3_GM.sf2 or your favourite GM soundfont separately.

lib/midikit.py

@@ -253,6 +253,22 @@ class MidiFile:
         self.tempos = []          # list[MPQN]
         self.key_sig = None       # (flats_sharps, minor_bool)
         self.time_sig = None      # (num, den_power)
+        self.loop = None          # (start_tick, end_tick)
+
+    def set_loop(self, start_tick, end_tick):
+        """Declare the loopable section (game BGM: intro plays once, then
+        the engine jumps back). Writes markers in every convention that
+        matters, so whichever player/engine you point at the file, it finds
+        the loop point:
+
+          LOOP_START / LOOP_END        - our convention, plain SMF markers
+          RPR LOOP START / RPR LOOP END - Reaper (and anything reading RPR)
+          LoopBegin / LoopEnd          - various game engines & trackers
+
+        All times are absolute ticks; use songkit.bar() to think in bars.
+        """
+        self.loop = (int(start_tick), int(end_tick))
+        return self
 
     def add_track(self, track):
         self.tracks.append(track)
@@ -271,6 +287,12 @@ class MidiFile:
         conductor = Track("Conductor")
         for mp in sorted(self.tempos, key=lambda m: m.tick):
             conductor.meta(mp.tick, 0x51, struct.pack(">I", mp.mpqn)[1:])
+        if self.loop:
+            start, end = self.loop
+            for tick, names in ((start, ("LOOP_START", "RPR LOOP START", "LoopBegin")),
+                                (end, ("LOOP_END", "RPR LOOP END", "LoopEnd"))):
+                for nm in names:
+                    conductor.meta(tick, 0x06, nm.encode("latin-1"))
         if self.time_sig:
             conductor.meta(0, 0x58, bytes([self.time_sig[0], self.time_sig[1], 24, 8]))
         if self.key_sig:
@@ -303,7 +325,8 @@ def read(path_or_bytes):
         tlen = struct.unpack(">I", data[pos + 4:pos + 8])[0]
         pos += 8
         end = pos + tlen
-        track = {"notes": [], "tempos": [], "name": None, "programs": {}, "cc": [], "bends": []}
+        track = {"notes": [], "tempos": [], "name": None, "programs": {},
+                 "cc": [], "bends": [], "markers": []}
         tick = 0
         running = None
         while pos < end:
@@ -325,6 +348,8 @@ def read(path_or_bytes):
                     track["tempos"].append((tick, int.from_bytes(mdata, "big")))
                 elif mtype == 0x03:
                     track["name"] = mdata.decode("latin-1")
+                elif mtype == 0x06:
+                    track["markers"].append((tick, mdata.decode("latin-1")))
                 elif mtype == 0x2F:
                     break
             elif status in (0xF0, 0xF7):

tests/smoke_test.py

@@ -26,6 +26,7 @@ d = Track("Drums", channel=9)
 drums(d, 0, 2, "rock")
 mf.add_track(lead); mf.add_track(bass); mf.add_track(acomp); mf.add_track(d)
 mf.tempos = [MPQN.from_bpm(0, 120)]
+mf.set_loop(bar(0), bar(2))          # loop the whole 2-bar demo
 path = "/tmp/midikit_smoke.mid"
 mf.write(path)
 
@@ -34,6 +35,13 @@ print("OK:", path, d["duration_sec"], "sec,",
       sum(len(t["notes"]) for t in d["tracks"]), "notes,",
       len(d["tracks"]), "tracks")
 
+# loop markers must survive the round-trip in all three conventions
+markers = sorted(set(m[1] for t in d["tracks"] for m in t["markers"]))
+expected = sorted(["LOOP_START", "LOOP_END", "RPR LOOP START", "RPR LOOP END",
+                   "LoopBegin", "LoopEnd"])
+assert markers == expected, "loop markers wrong: %s" % markers
+print("loop markers OK:", ", ".join(markers))
+
 # cross-check with mido if present (third-party parser as second opinion)
 try:
     import mido

tools/build_all.sh

@@ -15,6 +15,11 @@ for t in tunes/*.py; do
     python3 "$t"
 done
 
+for s in tunes/specs/*.json; do
+    echo "== $s"
+    python3 tools/make_tune.py "$s"
+done
+
 echo "== verifying MIDI"
 python3 - <<'EOF'
 import sys, glob

tools/make_tune.py

@@ -0,0 +1,192 @@
+#!/usr/bin/env python3
+"""
+make_tune.py — generate a fully-arranged retro MIDI from a JSON spec.
+
+This is the agent-friendly front door: no Python needed, just describe
+the tune. The style preset handles arrangement (instruments, accompaniment
+patterns, drums, vibrato, mix levels); you supply chords and a melody.
+
+Usage:
+    python3 tools/make_tune.py tunes/specs/my_tune.json
+    python3 tools/make_tune.py tunes/specs/my_tune.json --render   # + WAV
+
+Spec format (see tunes/specs/ for working examples):
+{
+  "name": "04_tea_break_at_the_terminal",   -> midi/<name>.mid
+  "style": "dos_adventure",                  # dos_adventure | n64_ambient | chiptune_racing
+  "bpm": 112,
+  "key": ["A", "minor"],                     # for the key signature meta
+  "chords": [["A","m"], ["F",""], ...],      # one [root, quality] per bar
+  "melody_start_bar": 4,
+  "melody": "A4-8 C5-8 E5-4 A5-2 | ...",     # bar-grid, '|' separators (linted 4/4)
+  "loop": {"start_bar": 4, "end_bar": 20},   # optional; LOOP_* markers
+  "counter": "...",                          # optional 2nd melody line (style-dependent)
+  "fills_at": [11, 19]                       # optional: drum fill at end of these bars
+}
+
+Chord qualities: maj m dim aug 7 maj7 m7 m7b5 6 m6 9 add9 sus2 sus4 sus
+"""
+import argparse, json, os, sys
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, os.path.join(HERE, "..", "lib"))
+
+from midikit import MidiFile, Track, MPQN, verify, note as N
+from songkit import (bar, melody, arp, bass_drive, drums, vibrato, crash,
+                     parse_score, QUALITIES, TPQ)
+
+KEY_PC = {"C": 0, "D": 2, "E": 4, "F": 5, "G": 7, "A": 9, "B": 11}
+# circle of fifths lookup for key signature meta (flats negative, sharps positive)
+MAJOR_KEYS = {"C": 0, "G": 1, "D": 2, "A": 3, "E": 4, "B": 5, "F#": 6, "C#": 7,
+              "F": -1, "Bb": -2, "Eb": -3, "Ab": -4, "Db": -5, "Gb": -6}
+
+
+def key_sig_for(tonic, mode):
+    if mode in ("minor", "m"):
+        # relative major is 3 semitones up
+        pc = (KEY_PC[tonic.upper()] + 3) % 12
+        name = {0: "C", 2: "D", 4: "E", 5: "F", 7: "G", 9: "A", 11: "B"}.get(pc)
+        if name is None:  # sharp-side minor keys
+            name = {1: "Db", 3: "Eb", 6: "F#", 8: "Ab", 10: "Bb"}[pc]
+        return MAJOR_KEYS[name], True
+    return MAJOR_KEYS[tonic.capitalize() if len(tonic) == 1 else tonic], False
+
+
+# ---------------------------------------------------------------------------
+# Style presets: (lead patch, accompaniment recipe)
+# ---------------------------------------------------------------------------
+def style_dos_adventure(mf, spec, chords):
+    n = len(chords)
+    lead = Track("Lead (square)", channel=0)
+    lead.program(0, "square lead"); lead.cc(0, 7, 100); lead.cc(0, 10, 54)
+    bass = Track("Bass", channel=2)
+    bass.program(0, "synth bass 1"); bass.cc(0, 7, 88); bass.cc(0, 10, 30)
+    acomp = Track("Arp (OPL)", channel=3)
+    acomp.program(0, "electric piano 1"); acomp.cc(0, 7, 64); acomp.cc(0, 10, 20)
+    d = Track("Drums", channel=9); d.cc(0, 7, 92)
+    mf.add_track(lead); mf.add_track(bass); mf.add_track(acomp); mf.add_track(d)
+    return dict(lead=lead, bass=bass, acomp=acomp, drums=d,
+                vibrato=(0.55, 5.5), arp_pattern="012321", arp_vel=70,
+                drums_pattern="rock", fill="dos_roll")
+
+
+def style_n64_ambient(mf, spec, chords):
+    lead = Track("Pan flute", channel=0)
+    lead.program(0, "pan flute"); lead.cc(0, 7, 92); lead.cc(0, 10, 58)
+    pad = Track("Warm pad", channel=1)
+    pad.program(0, "warm pad"); pad.cc(0, 7, 56); pad.cc(0, 10, 40)
+    harp = Track("Harp", channel=2)
+    harp.program(0, "orchestral harp"); harp.cc(0, 7, 70); harp.cc(0, 10, 84)
+    bass = Track("Cello", channel=3)
+    bass.program(0, "cello"); bass.cc(0, 7, 78); bass.cc(0, 10, 34)
+    mf.add_track(lead); mf.add_track(pad); mf.add_track(harp); mf.add_track(bass)
+    # whole-note pads + root bass
+    for i, (root, qual) in enumerate(chords):
+        third = 3 if qual.startswith("m") or qual.startswith("dim") else 4
+        for iv in (0, third, 7):
+            pad.note(bar(i), N(root + "3") + iv, TPQ * 4, 55)
+        bass.note(bar(i), N(root + "2"), TPQ * 4, 70)
+    return dict(lead=lead, bass=bass, acomp=harp, drums=None,
+                vibrato=(0.4, 4.5), arp_pattern="0121", arp_vel=56,
+                subdivision=2, arp_dur=TPQ, drums_pattern=None, fill=None)
+
+
+def style_chiptune_racing(mf, spec, chords):
+    lead = Track("Square lead", channel=0)
+    lead.program(0, "square lead"); lead.cc(0, 7, 90); lead.cc(0, 10, 52)
+    stabs = Track("Stabs", channel=2)
+    stabs.program(0, "electric piano 1"); stabs.cc(0, 7, 62); stabs.cc(0, 10, 24)
+    bass = Track("Bass", channel=3)
+    bass.program(0, "synth bass 2"); bass.cc(0, 7, 84); bass.cc(0, 10, 36)
+    d = Track("Drums", channel=9); d.cc(0, 7, 88)
+    mf.add_track(lead); mf.add_track(stabs); mf.add_track(bass); mf.add_track(d)
+    for i, (root, qual) in enumerate(chords):
+        for b in (0.5, 1.5, 2.5, 3.5):
+            for iv in QUALITIES[qual]:
+                stabs.note(bar(i, b), N(root + "4") + iv, TPQ // 2 - 40, 78)
+    return dict(lead=lead, bass=bass, acomp=None, drums=d,
+                vibrato=(0.45, 6.5), arp_pattern=None, arp_vel=0,
+                drums_pattern="drive", fill="dos_roll")
+
+
+STYLES = {"dos_adventure": style_dos_adventure,
+          "n64_ambient": style_n64_ambient,
+          "chiptune_racing": style_chiptune_racing}
+
+
+def build(spec):
+    chords = [(r, q) for r, q in spec["chords"]]
+    n = len(chords)
+    mf = MidiFile(tpq=TPQ)
+    mf.time_sig = (4, 2)
+    tonic, mode = spec.get("key", ["C", "major"])
+    mf.key_sig = key_sig_for(tonic, mode)
+    mf.tempos = [MPQN.from_bpm(0, spec["bpm"])]
+
+    st = STYLES[spec["style"]](mf, spec, chords)
+
+    start = spec.get("melody_start_bar", 0)
+    if spec.get("melody"):
+        melody(st["lead"], start, spec["melody"])
+        end_bar = start + len([s for s in spec["melody"].split("|") if s.strip()])
+        vibrato(st["lead"], bar(start), bar(min(end_bar, n)),
+                tempo_bpm=spec["bpm"], depth=st["vibrato"][0], rate=st["vibrato"][1])
+
+    if st.get("acomp") and st.get("arp_pattern"):
+        arp(st["acomp"], 0, chords, pattern=st["arp_pattern"],
+            velocity=st["arp_vel"],
+            subdivision=st.get("subdivision", 4),
+            duration=st.get("arp_dur"))
+    if st.get("bass") is not None and spec["style"] != "n64_ambient":
+        bass_drive(st["bass"], 0, chords, subdivision=2)
+
+    if st.get("drums") is not None and st.get("drums_pattern"):
+        drums(st["drums"], 0, n, st["drums_pattern"])
+        for b in spec.get("fills_at", []):
+            drums(st["drums"], b, 1, st["fill"] or "dos_roll", velocity_scale=0.85)
+        crash(st["drums"], bar(n - 1))
+
+    if spec.get("counter") and spec["style"] == "dos_adventure":
+        counter = Track("Counter (EP2)", channel=1)
+        counter.program(0, "electric piano 2")
+        counter.cc(0, 7, 80); counter.cc(0, 10, 90)
+        melody(counter, start, spec["counter"])
+        mf.add_track(counter)
+
+    if spec.get("loop"):
+        mf.set_loop(bar(spec["loop"]["start_bar"]), bar(spec["loop"]["end_bar"]))
+    return mf
+
+
+def main():
+    ap = argparse.ArgumentParser(description=__doc__)
+    ap.add_argument("spec", help="path to tune spec JSON")
+    ap.add_argument("--render", action="store_true", help="also render WAV via timidity")
+    args = ap.parse_args()
+
+    spec = json.load(open(args.spec))
+    mf = build(spec)
+    out = os.path.join(os.path.dirname(HERE), "midi", spec["name"] + ".mid")
+    os.makedirs(os.path.dirname(out), exist_ok=True)
+    mf.write(out)
+    d = verify(out)
+    markers = [m for t in d["tracks"] for m in t["markers"]]
+    print("OK:", out)
+    print("   %.1fs | %d notes | %d tracks | loop: %s" %
+          (d["duration_sec"], sum(len(t["notes"]) for t in d["tracks"]),
+           len(d["tracks"]),
+           "bars %d-%d" % (spec["loop"]["start_bar"], spec["loop"]["end_bar"])
+           if spec.get("loop") else "none"))
+    if markers:
+        print("   markers:", ", ".join(sorted(set(m[1] for m in markers))))
+    if args.render:
+        import subprocess
+        wav = os.path.join(os.path.dirname(HERE), "build", spec["name"] + ".wav")
+        os.makedirs(os.path.dirname(wav), exist_ok=True)
+        subprocess.run(["timidity", "-Ow", "-s", "44", out, "-o", wav],
+                       check=True, capture_output=True)
+        subprocess.run(["python3", os.path.join(HERE, "check_wav.py"), wav], check=True)
+
+
+if __name__ == "__main__":
+    main()

tunes/01_service_station_2am.py

@@ -132,8 +132,7 @@ def build():
     mf.add_track(lead); mf.add_track(counter); mf.add_track(bass)
     mf.add_track(acomp); mf.add_track(d)
     # loop points for game engines: intro plays once, A-B-A' loops
-    lead.marker(bar(4), "LOOP_START")
-    lead.marker(bar(28), "LOOP_END")
+    mf.set_loop(bar(4), bar(28))
     return mf
 
 

tunes/02_kestrel_over_the_fens.py

@@ -104,8 +104,7 @@ def build():
         harp.note(bar(23), N(p), TPQ * 6, 40)
 
     mf.add_track(lead); mf.add_track(pad); mf.add_track(harp); mf.add_track(bass)
-    lead.marker(bar(4), "LOOP_START")
-    lead.marker(bar(20), "LOOP_END")
+    mf.set_loop(bar(4), bar(20))
     return mf
 
 

tunes/03_late_equaliser.py

@@ -128,8 +128,7 @@ def build():
 
     mf.add_track(lead); mf.add_track(harm); mf.add_track(stabs)
     mf.add_track(bass); mf.add_track(d)
-    lead.marker(bar(2), "LOOP_START")
-    lead.marker(bar(26), "LOOP_END")
+    mf.set_loop(bar(2), bar(26))
     return mf
 
 

tunes/specs/04_tea_break_at_the_terminal.json

@@ -0,0 +1,18 @@
+{
+  "name": "04_tea_break_at_the_terminal",
+  "style": "dos_adventure",
+  "bpm": 112,
+  "key": ["A", "minor"],
+  "loop": {"start_bar": 4, "end_bar": 20},
+  "fills_at": [11, 19],
+  "melody_start_bar": 4,
+  "chords": [
+    ["A", "m"], ["F", ""], ["G", ""], ["A", "m"],
+    ["A", "m"], ["A", "m"], ["F", ""], ["F", ""],
+    ["G", ""], ["G", ""], ["A", "m"], ["A", "m"],
+    ["A", "m"], ["A", "m"], ["F", ""], ["G", ""],
+    ["A", "m"], ["G", ""], ["A", "m"], ["A", "m"],
+    ["A", "m"], ["F", ""], ["G", ""], ["A", "m"]
+  ],
+  "melody": "A4-8 C5-8 E5-4 A5-2 | G4-8 A4-8 C5-4 E5-2 | F5-8 E5-8 F5-8 A5-8 G5-4 F5-4 | E5-4 C5-4 F5-2 | D5-8 E5-8 G5-4 B5-2 | A5-8 B5-8 A5-8 G5-8 D5-4 G5-4 | C6-8 B5-8 C6-8 E6-8 D6-4 C6-4 | A5-2 E5-4 A5-4 | E5-8 G5-8 A5-4 C6-2 | B5-4 A5-4 E5-2 | A5-8 C6-8 A5-8 F5-8 E5-4 F5-4 | G5-8 A5-8 B5-4 D6-2 | C6-1 | B5-8 A5-8 G5-4 D5-2 | A5-8 G5-8 A5-8 C6-8 E6-4 D6-4 | A5-1"
+}