scaffolding-track

---

name: scaffolding-track description: Use when the user asks to "create a new track", "ajouter une track", "scaffolder une track X", or names a new track letter (A-W are taken, so X/Y/Z or beyond, OR overwriting an existing letter). Generates tracks/<LETTER>_<slug>.scd following the strict 23-track convention used in sound_algo: header banner, ~track !? { ~track.stop } guard, Routine with timed sections, ~bpm/~kickFreq/~melodyInst/~melodyNotes mutations, TempoClock.default.tempo = ~bpm/60, ~reload.value, Pdef list [\kickSeq, \hatSeq, \snareSeq, \clapSeq, \percSeq, \acidSeq, \melodySeq, \harmonySeq], section logs [L M:SS] description, and .wait between sections. Forgetting any of these breaks live performance — this skill enforces them.

Scaffolding a new track

Inputs to gather

Ask the user (or infer from context):

1. Letter : single uppercase letter. A-W are taken; default to next free letter (X, Y, ...).
2. Slug : short snake_case name (acid_journey, dub_techno, phonk).
3. Sections : list of (timestamp, name, BPM, vibe) tuples. Minimum 3 sections (intro, drop, outro).
4. Total duration : sum of section waits. Typical track = 5-10 minutes.
5. Style : melody instrument (\pad/\lead/\saw3/\rhodes/\koto/...), kick timbre, scale.

Template

// =====================================================================
//  <LETTER>_<slug>.scd
//  Track autonome -- Cmd+Entree sur le bloc (...) pour la lancer.
//  PREREQUIS : engine.scd evalue (les SynthDef + helpers doivent exister).
// =====================================================================

// --- TRACK <LETTER> : "<TITLE>" <DURATION> minutes -------------------
//   0:00 <s1> -> M:SS <s2> -> M:SS <s3> -> ... -> M:SS outro
(
~track !? { ~track.stop };
~track = Routine({
    "[<LETTER> 0:00] <section 1 description>...".postln;
    ~bpm = <BPM1>;
    ~kickFreq = 42; ~kickPitchAmt = 2.0; ~kickDecay = 0.5;
    ~kickAmp = 0.5; ~hatAmp = 0.08; ~melodyAmp = 0.14;
    ~melodyInst = \<inst1>;
    ~melodyAttack = 0.4; ~melodyRelease = 1.5; ~melodyCutoff = 1500;
    ~melodyNotes = [60,0,0,0, 0,0,0,0, 67,0,0,0, 0,0,0,0,
                    60,0,0,0, 0,0,0,0, 65,0,0,0, 0,0,0,0];
    TempoClock.default.tempo = ~bpm/60;
    ~reload.value;
    [\kickSeq, \hatSeq, \snareSeq, \clapSeq, \percSeq,
     \acidSeq, \melodySeq, \harmonySeq].do { |k| Pdef(k).play };
    <WAIT1>.wait;

    "[<LETTER> M:SS] <section 2 description>...".postln;
    ~bpm = <BPM2>;
    // ...mutations...
    TempoClock.default.tempo = ~bpm/60;
    ~reload.value;
    <WAIT2>.wait;

    // ... more sections ...

    "[<LETTER> END] outro".postln;
    ~masterFadeOut.(8);
}).play;
)

Mandatory invariants

• ~track !? { ~track.stop } BEFORE creating the new Routine. Without this, multiple Routines stack up.
• ~reload.value after every mutation of ~xxx parameters that feed Pdef.
• TempoClock.default.tempo = ~bpm/60 whenever ~bpm changes.
• One .postln log per section, format "[<L> M:SS] <description>..." -- this is parsed by tooling.
• .wait after each section (in seconds) -- sum should match total duration.
• Final ~masterFadeOut.(N) (or stop Pdef explicitly) to avoid hanging Pdef.

Variations within a section

Standard pattern for live mutations every 2-4 seconds inside a section :

30.do { |k|
    if (0.25.coin) { ~acidCutoff = rrand(600, 1400); ~reload.value };
    if (0.20.coin) {
        ~melodyNotes = ~genMelody.(0.55,
            [~scaleMinorPent, ~scaleDorian].choose);
        ~reload.value;
    };
    4.wait;  // 30 * 4 = 120s = 2 minutes
};

After scaffolding

1. Run validating-scd-files skill on the new file (P:0 B:0, TLB:N OK for tracks).
2. Optionally use registering-jump-section skill to expose sections via ~jumpTo.(\<L>, \<slug>).
3. Add the track to tests/e2e_09_tracks.scd parse list.

Anti-patterns to avoid

• Hardcoded path : never write absolute paths, use ~base.
• Section without log : silent debug nightmare during live.
• Total duration > 10 min without transition : auditory fatigue.
• Mutations without ~reload.value : Pdef stays stale, audible disconnect.
• Reusing an A-W letter : will overwrite an existing track.