Music Block

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---
name: ensemble-arranging
description: Arrange a melody or progression for a group in Music Block — jazz combo or big band horns, rock, pop or funk band, string quartet, choir, folk ensemble. Use whenever an example has three or more parts, or the user asks for an arrangement, a head, a chart, a section, a band or a choir.
---

Use this skill when a Music Block example has three or more parts, or when the
user asks for an arrangement of any kind. Six parts written one after another
against a chord symbol are not an arrangement: each part picks its own
alterations and passing tones, nothing rests, and the result clashes. An
arrangement is built in a fixed order, and the order is what this skill
enforces. Open the matching file in `references/` for the ensemble before
writing a note.

The tool checks every part against the chord symbol in effect on each beat
and rejects two spellings of one chord degree sounding together (natural 9
against b9, natural 5 against b13, major 3rd against minor 3rd, b7 against
major 7th). It warns about non-chord tones parked on strong beats, semitone
collisions, crossed or gapped section voices, a piano left hand doubling the
bass, and wind parts that never rest. Treat every one of those as a bug.

## Workflow

1. **Lead sheet first.** Write the melody and the chord symbols before any
   other part. Put the chord on every bar's `chord` field; when the harmony
   changes inside a bar, put the second chord on the `chord` field of the
   beat where it starts. Compose the melody with human-melodic-phrasing.
2. **Assign roles.** Every part gets exactly one role: lead, harmony
   (section voices under the lead), bass, comping or pad, time (drums).
   The reference file for the ensemble lists which instrument takes which
   role. Two parts never share the comping role in the same register.
3. **Decide one spelling per chord.** Before writing harmony parts, list the
   chord tones and the tensions you will use for each bar and stick to them
   in every part. If the symbol says alt, b9 or b13, no part plays the
   natural 9, 5 or 13 anywhere in that bar. If you want a natural 9, change
   the symbol.
4. **Derive the harmony parts from the lead, beat by beat.** Section voices
   share the lead's rhythm (block writing) or hold long notes under it
   (backgrounds). Each voice is within an octave of the voice above and
   never crosses it. Use only chord tones and agreed tensions on the lead's
   attacks; passing tones only where the lead has one too. Voicing recipes
   are in the reference file.
5. **Write the bass.** Roots on strong beats, approach notes into the next
   chord, one register, contrary motion against the melody where possible.
   With a bass part, the piano left hand stays above C3 and never plays
   roots in half notes.
6. **Add comping in the gaps.** Piano or guitar hits fall where the melody
   rests or holds, on offbeats, three or four notes per voicing, roots
   omitted when there is a bass.
7. **Add time.** Drums follow the style pattern in the reference, vary the
   kick every two to four bars, one fill at the phrase end.
8. **Plan the space.** Horns and voices phrase for two bars and rest for at
   least a beat. Backgrounds enter after the lead has started a phrase.
   Not every part plays in every bar; a part dropping out for a bar is an
   arranging tool. Keep the bar count equal by writing rests.
9. **Check the verticals.** For each beat, list what every part sounds.
   Confirm: one chord spelling, no semitone between parts unless both notes
   are chord tones or tensions of the symbol, upper voices within an octave
   of their neighbours, bass alone below C3, everything inside the
   instrument ranges from instrument-ranges-and-idioms.
10. Call the tool. If it returns harmony errors or warnings, fix the beat it
    names rather than defending it.

## Universal rules

- **Register map.** Bass instruments own E1 to G3. Comping and inner voices
  live between C3 and C5. The lead sits between C4 and C6. Pads hold the
  middle. Two parts in the same register playing the same rhythm is mud.
- **Guide tones carry the harmony.** In any voicing the 3rd and 7th must be
  present; the root belongs to the bass; the 5th is the first note to drop.
  Guide tones move by step from chord to chord.
- **Doubling.** Double the root or the 5th, never the 3rd or the 7th, and
  never the tension.
- **Motion.** Not every part changes notes on every beat. Hold at least one
  part through each bar. Melody and bass prefer contrary motion.
- **Low interval limits.** No thirds below C3, no seconds below G3, no
  minor 9ths against the bass anywhere.
- **Repetition is structure.** Bars 5 to 8 of an eight-bar arrangement
  reuse the rhythm and texture of bars 1 to 4 with a different ending. A new
  texture every bar sounds generated.
- **Music Block limits.** Up to eight parts; every part the same bar count;
  set `feel` for swing rather than writing triplets; keep every part
  engraved in an arrangement; write concert pitch, the tool transposes.

## Self-check before calling the tool

- The melody and chords were written first, and the chords are on every bar.
- Every part has one role and one register; no two parts comp together.
- One spelling per chord, obeyed by every part, alterations included.
- Section voices follow the lead's rhythm or hold, within an octave, never
  crossing.
- Bass has the roots; piano left hand stays above C3.
- Horns and voices rest at least every two bars; at least one part is silent
  in at least one bar.
- Bars 5 to 8 echo bars 1 to 4.

Referenced files: 6

View saved version →

---
name: human-melodic-phrasing
description: Compose melodies, licks, riffs, solos, bass lines and vocal lines for Music Block that sound like a musician played them rather than a scale generator. Use whenever composing any melodic line, and when a user says the result sounds robotic, mechanical or boring.
---

Use this skill when composing any pitched line for Music Block: a guitar lick,
a horn melody, a bass line, a vocal phrase, a piano right hand. It does not
cover fingering (see playable-fretted-parts) or instrument ranges (see
instrument-ranges-and-idioms).

The Music Block format has no dynamics, accents, staccato, grace notes, ties
or slurs. Everything human about the line must therefore come from four
things you do control: which notes, which rhythms, where the rests are, and
the technique markings on fretted instruments. Write with that in mind.

## Workflow

1. Name the idiom (blues, bebop, pop, folk, funk, classical) and open the
   matching file in `references/` if one exists. Its target notes and
   rhythmic habits override the generic advice here.
2. Design a motif: a two- to four-note idea with a distinctive rhythm that
   fits in half a bar or one bar.
3. Draw a phrase map before writing notes. For a 4-bar example: bar 1 states
   the motif, bar 2 repeats it with one change, bar 3 contrasts (new contour
   or register), bar 4 resolves and leaves space. For 2 bars: state, then
   answer. For 8 bars: two 4-bar phrases where the second ends more
   conclusively.
4. Place the target notes on strong beats, then fill between them.
5. Write the rhythm with rests and one or two syncopations, then the pitches.
6. Add technique markings (fretted) at the expressive points.
7. Run the self-check, then call the tool.

## Motif and repetition

- Repetition is what makes a line sound intentional. Every example longer
  than one bar should repeat at least one rhythmic or melodic cell.
- Vary a repeat by one parameter at a time: transpose it to the next chord,
  change its last note, displace it by an eighth, or invert its direction.
- A lick that never repeats anything is the single most common "generated"
  tell. So is a lick where every bar is different.

## Breathing and space

- End phrases before the barline or on the downbeat, then rest. Never fill
  every beat of every bar. In a 4-bar lick, at least one full beat is rest.
- Not every bar starts on beat 1. Use pickups: start a phrase on the "and" of
  4 or on beat 4 of the previous bar, with rest beats first so the tool keeps
  the notes in place.
- Long notes are phrasing too. A held note with vibrato after a run is how
  players mark a phrase end.

## Contour

- Mostly stepwise motion (seconds and thirds). One larger leap per phrase,
  then move back by step in the opposite direction.
- One clear peak per phrase, usually in the second half. Do not visit the
  peak twice.
- Avoid sawtooth scales: running straight up or straight down for more than
  five notes in a row without a change of direction or a repeated note.
- Avoid the arpeggio wander: chord tones cycled up and down in even values
  with no goal note.

## Target notes and harmony

- On beats 1 and 3, land on chord tones of the current chord (3rd and 7th
  say the most; the root says the least). Tensions and passing notes go on
  weak beats and offbeats and resolve by step.
- Over a dominant chord, tensions (b9, #9, #11, b13) resolve down by half
  step into a chord tone of the next chord. Over a ii-V-I, aim the line at
  the 3rd of the I chord on its downbeat.
- Approach a target from below by half step or from above by scale step;
  enclosures (one note above, one below, then the target) are idiomatic in
  jazz and blues.
- When the example demonstrates a scale, still phrase it: group the scale
  into a rhythm, end on a chord tone, add one rest.

## Rhythm

- Mix values inside a bar: eighths with one dotted figure, a triplet, or a
  quarter placed on an offbeat. A bar of eight identical eighths is fine once
  per example, not in every bar.
- Syncopate with rests and dotted notes, since ties are not available: a
  dotted quarter on the "and" of 1, an eighth rest before beat 3, a note on
  the "and" of 4 that ends the bar.
- For swing, bebop, shuffle and jazz-blues set the example's `feel` field
  and write straight eighths. Never fake swing with 12/8 or triplets.
- Keep one rhythmic motif recognisable across bars; change pitches more than
  rhythms.

## Technique markings as expression (fretted parts)

- Slide into the first note of a phrase or into a target note.
- Hammer-ons and pull-offs for pairs of eighths or sixteenths in a run;
  they mark the legato a player would use.
- Bends at phrase peaks; a full bend to the target with vibrato is a phrase
  ending in blues and rock.
- Vibrato on quarter notes or longer that end a phrase.
- Two to four markings per lick. A marking on every note is as robotic as
  none.

## Avoid list

- Unbroken streams of eighths or sixteenths with no rest.
- Straight scale runs of six or more notes in one direction.
- Identical rhythm in every bar.
- Every phrase starting on beat 1 and ending on the root.
- Arpeggios cycled up and down with no target.
- Constantly new material with nothing repeated.
- A wide leap followed by another leap in the same direction.
- Tension notes on strong beats without resolution.

## Self-check before calling the tool

- The line has one motif that appears at least twice, varied once.
- There is at least one rest per two bars and a pickup or offbeat start
  somewhere.
- Strong beats carry chord tones; tensions resolve by step.
- No run longer than five notes in one direction; one peak per phrase.
- Rhythm varies within bars but a cell recurs across bars.
- Swing is set through `feel`, not through note values.
- Fretted parts carry two to four technique markings at expressive points.

Referenced files: 4

View saved version →

---
name: instrument-ranges-and-idioms
description: Write Music Block parts for winds, brass, strings, voices, keyboards and drums that stay in each instrument's comfortable register and respect breath, hand and limb limits. Use when composing any non-fretted part, arranging for an ensemble or choir, or fixing a range warning.
---

Use this skill when a Music Block example contains a part written as `melody`
(single-staff pitched instruments), `hands` (piano, electric-piano, organ) or
`drums`. Fretted instruments have their own skill (playable-fretted-parts).

The tool warns when a note leaves an instrument's absolute range. This skill
is about the narrower region where players actually live, and about the
physical facts that ranges do not capture: lungs, hands, feet and slides.
Open the matching file in `references/` for the instrument family before
writing the part.

## Workflow

1. Look up the instrument's comfortable tessitura in `references/`. Write the
   part inside it; touch the extremes only at one climax, briefly.
2. Write pitches in CONCERT (sounding) pitch. The tool handles the written
   transposition for trumpet, clarinet, saxes and horn.
3. Shape phrases around the physical limit of the instrument: breath for
   winds and voices, bow and string crossings for strings, hand span for
   keyboards, two hands and two feet for drums.
4. For an ensemble, check the part interactions listed below.
5. Run the self-check and call the tool.

## Winds and voices breathe

- A phrase without a rest lasts at most 2 bars at 120 BPM or slower, 4 bars
  for a slow ballad of long notes, 1 bar for fast sixteenth passages. Then a
  rest of at least an eighth.
- Long held notes cost breath too; a whole note followed by a run needs a
  rest between them.
- Voices need more breath than winds: rests every 1 to 2 bars, phrase ends on
  a longer note.

## Brass endurance

- Brass players cannot sit at the top of the range. The highest fifth of the
  comfortable range appears for a beat or two per example, at the peak.
- Fast alternation between low and high register tires the player and
  sounds uneven; keep register changes gradual.

## Strings

- Open strings and first-position notes are strongest for double stops.
- Fast passages stay on adjacent strings; large leaps across three strings
  need a longer note before them.
- Double stops on adjacent strings only, mostly thirds, sixths and octaves;
  no double stops in fast sixteenths.

## Keyboards (hands)

- Right hand and left hand must have the same number of bars.
- Hand span is an octave for running figures, a ninth for a held chord, five
  notes per hand at most. The tool warns above a ninth.
- Left hand sits between C2 and C4, right hand between C4 and C6, meeting in
  the middle only for shared chords. Hands do not cross.
- Left-hand patterns: root and fifth, root-fifth-octave, Alberti bass, stride
  (root, then a chord an octave or tenth above), walking quarters, held shell
  voicings for jazz comping. Pick one per example and keep it.
- Both hands in sixteenths at once is virtuoso writing; for an exercise give
  one hand the motion and the other chords or held notes.
- No position shift every beat at tempo; a hand stays over five to eight keys
  for at least a bar.

## Drums

- Two hands, two feet. Per beat at most: kick (foot), hi-hat pedal (other
  foot), and two hand voices among snare, hi-hat, ride, toms and crash.
- Ride and closed hi-hat played by hand at the same time is a third hand;
  do not write it. A hi-hat pedal note while the hi-hat is played by hand is
  fine only as the closing "chick".
- Groove first: hi-hat or ride keeps eighths or quarters, snare on 2 and 4,
  kick on 1 and 3 with one syncopated kick per bar. Vary the kick every 2 or
  4 bars, not every bar.
- Humanise with ghost notes (a snare on the sixteenth before beat 2 or 4), an
  open hi-hat on the "and" of 4, and one fill in the last bar before a repeat
  using toms and ending on crash plus kick on the downbeat.

## Ensemble interactions

- Give parts different rhythms: if the melody moves in eighths, the
  accompaniment moves in quarters or half notes, and the bass in quarters.
- Do not have every part change notes on every beat; hold at least one part
  through each bar.
- Keep a bass instrument alone in its register; other parts stay above it by
  at least a fifth to avoid mud.
- Inner voices move by step or common tone; outer voices define the shape.
- Choir (SATB): soprano and alto within an octave of each other, alto and
  tenor within an octave, tenor and bass up to a twelfth apart; no voice
  crossing; bass roots on strong beats.

## Self-check before calling the tool

- Every part sits inside its comfortable tessitura except one brief peak.
- Wind and vocal phrases have a rest at least every 2 bars.
- Brass does not sit at the top of its range.
- Keyboard hands span at most a ninth, five notes each, no crossing, one
  left-hand pattern.
- Drum beats need at most two hands and two feet.
- Ensemble parts differ in rhythm, hold through bars, and never cross.

Referenced files: 7

View saved version →

---
name: playable-fretted-parts
description: Write guitar, electric guitar, bass and ukulele parts (string/fret "bars" for Music Block) that a human can actually finger at the stated tempo. Use before composing any fretted lick, riff, exercise, bass line or chord voicing, and when fixing a playability warning.
---

Use this skill whenever a Music Block example contains a part written as `bars`
(string + fret per note) for guitar, electric-guitar, bass or ukulele. The
tool only rejects impossible input (two notes on one string, a string that does
not exist) and warns about chords wider than five frets. Everything below is
what the validator cannot judge and what separates real TAB from random
string/fret pairs.

## Workflow

1. Pick the position first. A position is the fret under the index finger.
   The hand covers that fret plus the next three (one finger per fret) and
   any open string. Write the whole phrase inside that window before
   considering a shift.
2. Choose strings for the line, not just pitches. Every pitch exists in
   several places; put a fast run on two or three adjacent strings inside the
   position rather than walking up one string.
3. Place shifts deliberately: on a slide, on an open string, on a long note,
   or at a rest. Never shift in the middle of a run of eighths or sixteenths.
4. Add technique markings where a player would use them (below). They are
   the main way to make a line sound human, because the format has no
   dynamics or articulation.
5. Before calling the tool, run the self-check at the end of this file.

## Left hand: positions and stretches

- One finger per fret. Inside a beat, fretted notes span at most 4 frets
  (open strings do not count). Across a phrase without a shift, at most 5.
- Above fret 12 the frets are closer; a span of 5 to 6 is fine there. Below
  fret 5 the frets are wide; keep spans to 4.
- A stretch of one extra fret with the pinky is fine for a single note, not
  for a repeated figure.
- Consecutive beats that jump more than 5 frets need a slide, a rest, or an
  open string between them. If none fits, refinger the second note on
  another string in the current position.
- Do not mirror keyboard thinking: a guitar run that changes string on every
  note is awkward. Group two to four notes per string.

## Tempo limits

| Tempo | Sixteenths | Eighths | Position shifts |
| --- | --- | --- | --- |
| up to 90 BPM | anywhere inside the position | free | on any beat boundary |
| 90 to 140 BPM | adjacent frets and adjacent strings only | free inside the position | at most one per bar, on a slide or long note |
| above 140 BPM | short bursts of 4 or fewer, on one string with hammer or pull | inside the position, at most two string changes per beat | none mid-phrase |

Triplet eighths count as eighths; sextuplets count as sixteenths.

## Technique markings

- `hammer` and `pull` connect this beat to the next beat on the SAME string,
  1 to 3 frets apart. Hammer goes up in pitch, pull goes down. Never mark a
  hammer or pull into a note on a different string or the last beat of the
  example.
- `slide` connects to the next beat on the same string. Keep slides to 5
  frets or less in fast passages; long slides only into a held note.
- `bend-half` and `bend-full` belong on strings 1 to 3 at fret 5 or higher.
  Bending a wound string (4 to 6) or a low fret is possible but rare; avoid it
  unless the user asks. A full bend needs the note below the target: write the
  fret of the starting pitch, the bend supplies the rest.
- `vibrato` on notes of a quarter or longer, especially phrase endings and
  bend peaks.
- `palm-mute` on low-string riff notes, typically eighths on strings 5 and 6.
- `let-ring` on arpeggiated chord tones on different strings.
- A single lick usually carries two to four markings, not one per note.

## Chord voicings

- At most 4 fretted notes in a shape unless one fret is a barre (two or more
  notes on the same fret with nothing lower). A barre covers all higher
  strings at that fret, so an open string cannot sit between barred strings.
- Fretted notes in a shape span at most 4 frets below fret 5, 5 frets higher
  up. The tool warns above 5.
- Every note in a chord is on a distinct string. Prefer common shapes: open
  chords, E and A shape barres, drop-2 and drop-3 voicings on strings 1 to 4
  or 2 to 5, shell voicings (root, 3rd, 7th) for jazz comping.
- Comping under a lick: 3 or 4 note voicings on the middle strings, not
  6-string barres on every beat.
- Chord notes played together must be reachable at the same time; do not
  combine a note at fret 2 on string 6 with fret 8 on string 1.

## Bass

- Same one-finger-per-fret rule over 4 frets; many players use a 3-fret
  span below fret 5. Open strings are the usual shift point.
- Walking bass: quarter notes, roots or fifths on beats 1 and 3, chord tones
  or chromatic approach notes on beats 2 and 4, at most one leap per bar.
- Sixteenth-note bass lines stay on one or two strings and repeat a pattern.
- Bass lines rarely go above fret 12 or use chords; keep the register in
  frets 0 to 9 unless the user wants a solo.

## Ukulele

- Standard tuning is re-entrant: string 4 (G4) is higher than string 3 (C4).
  Melodies live on strings 1 and 2, sometimes 3. Do not write a "low" bass
  note on string 4.
- Position window is 4 frets; chords use all four strings; no bends.

## Self-check before calling the tool

- Each phrase sits inside one 4-fret window (plus open strings) or shifts at
  a slide, open string, long note or rest.
- No beat-to-beat jump larger than 5 frets without one of those.
- Sixteenths obey the tempo table.
- Every hammer, pull and slide has a following note on the same string.
- Bends are on strings 1 to 3 at fret 5 or above.
- Chord shapes have at most 4 fretted notes or a barre, span 4 to 5 frets,
  and contain no open string between barred strings.
- Bass and ukulele parts follow their sections.

If the tool returns a playability warning, treat it as a bug in the example
and re-voice the beat rather than explaining the warning to the user.

Referenced files: 1