Low-to-high fingerings by default (high_to_low opt-out) — v0.43.0

Fretboard string lists and Fingering positions/string-names now read
low-to-high (lowest-pitched string first), matching how chord diagrams
and tablature are conventionally written. Pass high_to_low=True to any
fretboard constructor to restore the pre-0.43 high-to-low behavior.

Design: each board keeps a private canonical (high-to-low) tone store
so the fingering scorer and GUITAR_OVERRIDES table stay untouched; a
single _orient() helper re-orients at the user-facing boundary (and,
being self-inverse, also canonicalizes custom tuning/position input).
Fingering carries its own orientation flag and presents oriented
positions/names via properties. The fingering cache key now includes
orientation so the two orderings don't collide.

to_tab() and Part.strum() now sort by pitch internally, so their output
is identical regardless of board orientation.

- All 25 instrument presets gain a high_to_low param, routed through a
  canonical build path.
- Tests updated for the new default; added orientation-specific tests.
- Docs/examples flipped to low-to-high; chord_charts.py example now uses
  the built-in Fingering.tab() instead of a hand-rolled renderer.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,29 @@
 
 All notable changes to PyTheory are documented here.
 
+## 0.43.0
+
+- **BREAKING — fingerings now read low-to-high by default.** `Fretboard`
+  string lists and `Fingering` positions/string-names now run from the
+  **lowest-pitched string first** (e.g. standard guitar reads `E A D G B E`),
+  matching how chord diagrams and tablature are conventionally written.
+  Previously they ran high-to-low (`E B G D A E`). This affects
+  `Fretboard.tones`, iteration over a fretboard, `repr`, `chord()`, `tab()`,
+  `chart()`, and `fingering()` output.
+
+  To restore the pre-0.43 high-to-low behavior, pass **`high_to_low=True`**
+  to any fretboard constructor — `Fretboard.guitar(high_to_low=True)`,
+  `Fretboard(tones=..., high_to_low=True)`, and likewise on every instrument
+  preset (`bass`, `ukulele`, `mandolin`, … `keyboard`).
+
+  The flip also applies to **input**: a custom tuning tuple passed to
+  `Fretboard.guitar(...)` and manual fret positions passed to
+  `fingering(*positions)` are now read in the board's orientation
+  (low-to-high by default).
+
+  `to_tab()` and `Part.strum()` are unaffected — they sort by pitch
+  internally and produce identical output regardless of orientation.
+
 ## 0.42.1
 
 - **Fretboard tuning support** — `to_tab()` now accepts `Fretboard` objects as

docs/guide/chords.rst

@@ -94,11 +94,11 @@ PyTheory includes 144 pre-built chords (12 roots x 12 qualities):
 
    >>> fb = Fretboard.guitar()
    >>> fb.chord("C")
-   Fingering(e=0, B=1, G=0, D=2, A=3, E=x)
+   Fingering(E=x, A=3, D=2, G=0, B=1, e=0)
    >>> fb.chord("Am")
-   Fingering(e=0, B=1, G=2, D=2, A=0, E=x)
+   Fingering(E=x, A=0, D=2, G=2, B=1, e=0)
    >>> fb.chord("G7")
-   Fingering(e=1, B=0, G=0, D=0, A=2, E=3)
+   Fingering(E=3, A=2, D=0, G=0, B=0, e=1)
 
 You can also build chords directly with ``Chord.from_name()``:
 
@@ -503,9 +503,16 @@ are standard arranging techniques for spreading chord tones across registers:
    >>> cmaj7 = Chord.from_symbol("Cmaj7")
    >>> cmaj7.close_voicing()
    <Chord C major 7th>
+   >>> cmaj7.open_voicing()
+   <Chord C major 7th>
    >>> cmaj7.drop2()
    <Chord C major 7th>
 
+``open_voicing()`` takes the close voicing and raises every other
+non-root tone by an octave, spreading the chord across two octaves.
+The result is a wider, more spacious sound — common in orchestral
+writing and piano ballads where you want the harmony to breathe.
+
 Chord Extensions
 ----------------
 
@@ -596,6 +603,23 @@ music that doesn't follow traditional harmony, this is the tool.
 Major and minor triads share the same prime form — they're inversions
 of each other in pitch class space.
 
+The **normal form** is the intermediate step — the most compact ascending
+arrangement of pitch classes before transposition. It preserves the
+actual pitch classes (not transposed to 0), so it tells you which
+specific notes are in the set:
+
+.. code-block:: pycon
+
+   >>> Chord.from_tones("C", "E", "G").normal_form
+   (0, 4, 7)
+
+   >>> Chord.from_tones("A", "C", "E").normal_form
+   (9, 0, 4)
+
+Normal form keeps the original pitch classes; prime form transposes to 0
+for comparison. Use ``normal_form`` when you care about which notes,
+``prime_form`` when you care about the abstract shape.
+
 .. code-block:: pycon
 
    >>> Chord.from_tones("C", "E", "G").forte_number

docs/guide/fretboard.rst

@@ -18,19 +18,28 @@ positions are just semitone steps along the fingerboard.
 Guitars
 -------
 
-`Standard guitar tuning <https://en.wikipedia.org/wiki/Guitar_tunings>`_
-(high to low)::
+`Standard guitar tuning <https://en.wikipedia.org/wiki/Guitar_tunings>`_::
 
-    String 1: E4  (highest)
-    String 2: B3
-    String 3: G3
-    String 4: D3
-    String 5: A2
     String 6: E2  (lowest)
+    String 5: A2
+    String 4: D3
+    String 3: G3
+    String 2: B3
+    String 1: E4  (highest)
 
 This tuning uses intervals of a perfect 4th (5 semitones) between most
 strings, except between G and B which is a major 3rd (4 semitones).
 
+.. note::
+
+   Since **v0.43.0**, fingerings and string lists read **low to high**
+   (lowest-pitched string first) by default — matching how chord
+   diagrams and tab are conventionally written. To get the pre-0.43
+   high-to-low order, pass ``high_to_low=True`` to any fretboard
+   constructor, e.g. ``Fretboard.guitar(high_to_low=True)``. A custom
+   tuning tuple and manual ``fingering()`` positions are likewise read
+   in the board's orientation.
+
 .. code-block:: pycon
 
    >>> from pytheory import Fretboard
@@ -192,12 +201,12 @@ on any instrument. It scores each possibility by:
    >>> fb = Fretboard.guitar()
    >>> f = fb.chord("C")
    >>> f
-   Fingering(e=0, B=1, G=0, D=2, A=3, E=x)
+   Fingering(E=x, A=3, D=2, G=0, B=1, e=0)
 
    >>> f['A']
    3
    >>> f[1]
-   1
+   3
 
    >>> f.identify()
    'C major'
@@ -210,11 +219,11 @@ You can also go from fret positions to chord identification:
 
 .. code-block:: pycon
 
-   >>> # "What chord am I playing?"
+   >>> # "What chord am I playing?" (positions read low to high)
    >>> fb = Fretboard.guitar()
-   >>> f = fb.fingering(0, 0, 0, 2, 2, 0)
+   >>> f = fb.fingering(0, 2, 2, 0, 0, 0)
    >>> f
-   Fingering(e=0, B=0, G=0, D=2, A=2, E=0)
+   Fingering(E=0, A=2, D=2, G=0, B=0, e=0)
    >>> f.identify()
    'E minor'
 
@@ -223,14 +232,14 @@ Reading Fingerings
 
 Each position is labeled with its string name. Duplicate string names
 are disambiguated — on a standard guitar, high E appears as ``e`` and
-low E as ``E``::
+low E as ``E``. Strings read low to high (lowest first)::
 
-    e|--0--    (open — E)
-    B|--1--    (fret 1 — C)
-    G|--0--    (open — G)
-    D|--2--    (fret 2 — E)
+    E|--x--    (muted — low E)
     A|--3--    (fret 3 — C)
-    E|--x--    (muted)
+    D|--2--    (fret 2 — E)
+    G|--0--    (open — G)
+    B|--1--    (fret 1 — C)
+    e|--0--    (open — high E)
 
 A value of ``x`` (``None``) means the string is muted (not played).
 
@@ -243,12 +252,12 @@ For a more visual representation, use ``tab()``:
 
    >>> print(fb.tab("C"))
    C major
-   e|--0--
-   B|--1--
-   G|--0--
-   D|--2--
-   A|--3--
    E|--x--
+   A|--3--
+   D|--2--
+   G|--0--
+   B|--1--
+   e|--0--
 
 Generating Full Charts
 ----------------------
@@ -261,7 +270,7 @@ Generate fingerings for every chord at once:
    >>> chart = fb.chart()
 
    >>> chart["C"]
-   Fingering(e=0, B=1, G=0, D=2, A=3, E=x)
+   Fingering(E=x, A=3, D=2, G=0, B=1, e=0)
 
    >>> # Works with any instrument
    >>> uke_chart = Fretboard.ukulele().chart()
@@ -303,19 +312,19 @@ Any instrument can be modeled with custom string tunings:
 
    >>> from pytheory import Tone, Fretboard
 
-   >>> # Baritone ukulele (DGBE — top 4 guitar strings)
+   >>> # Baritone ukulele (DGBE — top 4 guitar strings, low to high)
    >>> bari_uke = Fretboard(tones=[
-   ...     Tone.from_string("E4"),
-   ...     Tone.from_string("B3"),
-   ...     Tone.from_string("G3"),
    ...     Tone.from_string("D3"),
+   ...     Tone.from_string("G3"),
+   ...     Tone.from_string("B3"),
+   ...     Tone.from_string("E4"),
    ... ])
 
-   >>> # Tres cubano (Cuban guitar, 3 doubled courses)
+   >>> # Tres cubano (Cuban guitar, 3 doubled courses, low to high)
    >>> tres = Fretboard(tones=[
-   ...     Tone.from_string("E4"),
-   ...     Tone.from_string("B3"),
    ...     Tone.from_string("G3"),
+   ...     Tone.from_string("B3"),
+   ...     Tone.from_string("E4"),
    ... ])
 
 If it has strings, you can model it. Define the tuning, and PyTheory handles the rest -- fingerings, charts, scale diagrams, all of it. Got a weird instrument or a custom tuning? That's what the ``Fretboard`` constructor is for.

docs/guide/nashville-blues-tabs.rst

@@ -0,0 +1,404 @@
+Nashville Numbers, Blues Scales, and Tablature
+===============================================
+
+Three tools that work together: the Nashville number system for writing
+chord charts, blues scales for improvisation, and tablature for seeing
+where to put your fingers. This guide covers all three and shows how
+they connect.
+
+The Nashville Number System
+---------------------------
+
+The `Nashville number system <https://en.wikipedia.org/wiki/Nashville_Number_System>`_
+replaces chord names with Arabic numerals (1, 2, 3...) so that a chart
+works in **any key**. It's the standard chart format in Nashville
+recording studios — a session musician can read a number chart and
+transpose on the fly without rewriting anything.
+
+The idea is simple: each number refers to a **scale degree**. In any
+major key, 1 is the tonic chord, 4 is the subdominant, 5 is the
+dominant, and so on. The chord quality (major, minor, diminished) is
+determined by the key — you don't need to write it out.
+
+In C major::
+
+    1 = C major      5 = G major
+    2 = D minor      6 = A minor
+    3 = E minor      7 = B diminished
+    4 = F major
+
+In G major::
+
+    1 = G major      5 = D major
+    2 = A minor      6 = E minor
+    3 = B minor      7 = F# diminished
+    4 = C major
+
+Same numbers, different key, different chords — but the same harmonic
+relationships.
+
+Using Nashville Numbers in PyTheory
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Both :class:`~pytheory.scales.Key` and :class:`~pytheory.scales.TonedScale`
+support the ``nashville()`` method:
+
+.. code-block:: pycon
+
+   >>> from pytheory import Key
+
+   >>> key = Key("C", "major")
+   >>> [c.identify() for c in key.nashville(1, 4, 5, 1)]
+   ['C major', 'F major', 'G major', 'C major']
+
+   >>> # Same progression, different key — just change the Key
+   >>> key_g = Key("G", "major")
+   >>> [c.identify() for c in key_g.nashville(1, 4, 5, 1)]
+   ['G major', 'C major', 'D major', 'G major']
+
+Nashville numbers and Roman numerals produce the same result — they're
+two notations for the same concept:
+
+.. code-block:: pycon
+
+   >>> key = Key("G", "major")
+   >>> nash = [c.identify() for c in key.nashville(1, 5, 6, 4)]
+   >>> roman = [c.identify() for c in key.progression("I", "V", "vi", "IV")]
+   >>> nash == roman
+   True
+
+Seventh Chords
+~~~~~~~~~~~~~~
+
+Suffix ``"7"`` to get seventh chords — essential for jazz and blues
+charts:
+
+.. code-block:: pycon
+
+   >>> key = Key("C", "major")
+   >>> [c.identify() for c in key.nashville("17", "47", "57")]
+   ['C major 7th', 'F major 7th', 'G dominant 7th']
+
+Nashville vs. Roman Numerals
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When should you use which?
+
+- **Nashville numbers** — faster to type, easier to read at a glance,
+  standard in studio sessions. Use ``key.nashville(1, 4, 5, 1)``.
+- **Roman numerals** — encode chord quality (uppercase = major,
+  lowercase = minor), standard in theory textbooks. Use
+  ``key.progression("I", "IV", "V", "I")``.
+
+Both are fully supported. Use whichever fits your workflow.
+
+Blues Scales
+------------
+
+The `blues scale <https://en.wikipedia.org/wiki/Blues_scale>`_ is a
+six-note scale built from the minor pentatonic plus one chromatic
+passing tone — the **blue note** (flat 5th). That single added note
+gives the blues its tension and character.
+
+The blues system in PyTheory includes several related scales:
+
+====================  =====  ==================================
+Scale                 Notes  Character
+====================  =====  ==================================
+minor pentatonic      5      Foundation of rock and blues soloing
+major pentatonic      5      Bright, country, pop
+blues                 6      Minor pentatonic + blue note (b5)
+major blues           6      Major pentatonic + blue note (b3)
+dominant              7      Mixolydian — dominant 7th sound
+minor                 7      Dorian-like — minor with natural 6th
+====================  =====  ==================================
+
+Building Blues Scales
+~~~~~~~~~~~~~~~~~~~~~
+
+Use ``system="blues"`` when creating a :class:`~pytheory.scales.TonedScale`:
+
+.. code-block:: pycon
+
+   >>> from pytheory import TonedScale
+
+   >>> c = TonedScale(tonic="C4", system="blues")
+
+   >>> c["minor pentatonic"].note_names
+   ['C', 'Eb', 'F', 'G', 'Bb', 'C']
+
+   >>> c["blues"].note_names
+   ['C', 'Eb', 'F', 'Gb', 'G', 'Bb', 'C']
+
+   >>> c["major pentatonic"].note_names
+   ['C', 'D', 'E', 'G', 'A', 'C']
+
+   >>> c["major blues"].note_names
+   ['C', 'D', 'Eb', 'E', 'G', 'A', 'C']
+
+The Anatomy of a Blues Scale
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The blues scale in C::
+
+    C  Eb  F  Gb  G  Bb  C
+    1  b3  4  b5  5  b7  8
+
+    Root ──┐
+           ├── minor 3rd (3 semitones)
+           ├── perfect 4th (5 semitones)
+           ├── diminished 5th (6 semitones) ← the "blue note"
+           ├── perfect 5th (7 semitones)
+           ├── minor 7th (10 semitones)
+           └── octave (12 semitones)
+
+The blue note (Gb/F#) sits between the 4th and 5th — a dissonant,
+unstable pitch that resolves up or down. It's what makes blues sound
+like blues.
+
+The 12-Bar Blues
+~~~~~~~~~~~~~~~~
+
+The `12-bar blues <https://en.wikipedia.org/wiki/Twelve-bar_blues>`_ is
+the most important chord progression in American music. It uses the
+Nashville numbers 1, 4, and 5::
+
+    | 1  | 1  | 1  | 1  |
+    | 4  | 4  | 1  | 1  |
+    | 5  | 4  | 1  | 5  |
+
+In the key of A:
+
+.. code-block:: pycon
+
+   >>> from pytheory import Key
+
+   >>> key = Key("A", "major")
+   >>> bars = key.nashville(1,1,1,1, 4,4,1,1, 5,4,1,5)
+   >>> [c.identify() for c in bars]
+   ['A major', 'A major', 'A major', 'A major', 'D major', 'D major', 'A major', 'A major', 'E major', 'D major', 'A major', 'E major']
+
+For an authentic blues sound, use dominant 7th chords:
+
+.. code-block:: pycon
+
+   >>> bars_7 = key.nashville("17","17","17","17", "47","47","17","17", "57","47","17","57")
+   >>> [c.identify() for c in bars_7]
+   ['A major 7th', 'A major 7th', 'A major 7th', 'A major 7th', 'D major 7th', 'D major 7th', 'A major 7th', 'A major 7th', 'E dominant 7th', 'D major 7th', 'A major 7th', 'E dominant 7th']
+
+Or use the built-in named progression:
+
+.. code-block:: pycon
+
+   >>> key = Key("A", "major")
+   >>> blues = key.common_progressions()["12-bar blues"]
+   >>> [c.identify() for c in blues]
+   ['A major', 'A major', 'A major', 'A major', 'D major', 'D major', 'A major', 'A major', 'E major', 'D major', 'A major', 'E major']
+
+Blues Scale on the Fretboard
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Visualize the blues scale on guitar to see the patterns:
+
+.. code-block:: pycon
+
+   >>> from pytheory import Fretboard, TonedScale
+
+   >>> fb = Fretboard.guitar()
+   >>> blues = TonedScale(tonic="A4", system="blues")["blues"]
+   >>> print(fb.scale_diagram(blues, frets=12))
+       0   1   2   3   4   5   6   7   8   9  10  11  12
+   E| - | - | - | - | - | A | - | - | C | - | D | Eb| E |
+   B| - | - | - | D | Eb| E | - | - | - | - | A | - | - |
+   G| - | - | A | - | - | C | - | D | Eb| E | - | - | - |
+   D| - | - | - | - | A | - | - | C | - | D | Eb| E | - |
+   A| A | - | - | C | - | D | Eb| E | - | - | - | - | A |
+   E| - | - | - | - | - | A | - | - | C | - | D | Eb| E |
+
+The minor pentatonic (same scale without the Eb) is the most-played
+scale in rock guitar. Add the blue note and you have the full blues
+scale — the same shapes, one extra fret.
+
+Tablature
+---------
+
+`Tablature <https://en.wikipedia.org/wiki/Tablature>`_ (tab) shows
+**where to put your fingers** rather than what notes to play. Each line
+represents a string; numbers indicate fret positions. PyTheory generates
+tabs at three levels:
+
+1. **Chord tabs** — single chord fingerings
+2. **Part tabs** — full melody/sequence notation
+3. **Score tabs** — extract a part from a multi-part score
+
+Chord Tablature
+~~~~~~~~~~~~~~~~
+
+Get the tab for any chord on any instrument:
+
+.. code-block:: pycon
+
+   >>> from pytheory import Fretboard
+
+   >>> fb = Fretboard.guitar()
+   >>> print(fb.tab("C"))
+   C major
+   e|--0--
+   B|--1--
+   G|--0--
+   D|--2--
+   A|--3--
+   E|--x--
+
+   >>> print(fb.tab("Am"))
+   A minor
+   e|--0--
+   B|--1--
+   G|--2--
+   D|--2--
+   A|--0--
+   E|--x--
+
+   >>> print(fb.tab("E7"))
+   E dominant 7th
+   e|--0--
+   B|--0--
+   G|--1--
+   D|--0--
+   A|--2--
+   E|--0--
+
+Works with any instrument:
+
+.. code-block:: pycon
+
+   >>> uke = Fretboard.ukulele()
+   >>> print(uke.tab("C"))
+   C major
+   A|--3--
+   E|--0--
+   C|--0--
+   G|--0--
+
+Reading Tab Notation
+~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    e|--0--    ← open string (don't fret, just pluck)
+    B|--1--    ← press fret 1
+    G|--0--    ← open string
+    D|--2--    ← press fret 2
+    A|--3--    ← press fret 3
+    E|--x--    ← muted (don't play this string)
+
+- Each line is a string (highest pitch at top, lowest at bottom)
+- Numbers are fret positions (0 = open, 1-24 = fretted)
+- ``x`` means the string is muted / not played
+- ``|`` marks measure boundaries in sequence tabs
+
+Part Tablature
+~~~~~~~~~~~~~~~
+
+Generate tab from a composed part using ``to_tab()``:
+
+.. code-block:: python
+
+   from pytheory import Score, Key, Duration
+
+   score = Score("4/4", bpm=120)
+   lead = score.part("lead", synth="saw")
+
+   # A simple blues lick
+   for note in ["A4", "C5", "D5", "Eb5", "E5", "G5", "A5"]:
+       lead.add(note, Duration.QUARTER)
+
+   print(lead.to_tab())
+
+This outputs standard ASCII tab with measure lines, mapping each note
+to the most playable string and fret position.
+
+Tuning Options
+~~~~~~~~~~~~~~
+
+The ``to_tab()`` method supports multiple tunings:
+
+.. code-block:: python
+
+   # Standard guitar (default)
+   lead.to_tab(tuning="guitar")
+
+   # 4-string bass
+   lead.to_tab(tuning="bass")
+
+   # Drop D guitar
+   lead.to_tab(tuning="drop_d")
+
+   # Any Fretboard object — use any of the 25+ instrument presets
+   from pytheory import Fretboard
+   lead.to_tab(tuning=Fretboard.mandolin())
+   lead.to_tab(tuning=Fretboard.banjo())
+
+   # Custom tuning as MIDI note numbers (low string first)
+   lead.to_tab(tuning=[40, 45, 50, 55, 59, 64])
+
+Score Tablature
+~~~~~~~~~~~~~~~~
+
+Extract tab from a multi-part score:
+
+.. code-block:: python
+
+   score = Score("4/4", bpm=120)
+   rhythm = score.part("rhythm", synth="saw")
+   lead = score.part("lead", synth="triangle")
+   bass = score.part("bass", synth="sine")
+
+   # ... compose parts ...
+
+   # Tab the lead part
+   print(score.to_tab("lead"))
+
+   # Tab the first non-drum part (if no name given)
+   print(score.to_tab())
+
+   # Bass tab
+   print(score.to_tab("bass", tuning="bass"))
+
+Putting It All Together
+-----------------------
+
+Here's a complete example that uses all three features — Nashville
+numbers for the chord progression, the blues scale for the melody, and
+tab export to see the fingering:
+
+.. code-block:: python
+
+   from pytheory import Key, TonedScale, Fretboard, Score, Duration
+
+   # 1. Nashville numbers for the progression
+   key = Key("A", "major")
+   chords = key.nashville(1, 1, 1, 1, 4, 4, 1, 1, 5, 4, 1, 5)
+
+   # 2. Blues scale for the melody
+   blues = TonedScale(tonic="A4", system="blues")["blues"]
+
+   # 3. Compose a score
+   score = Score("4/4", bpm=120)
+   rhythm = score.part("rhythm", synth="saw", envelope="pad")
+   lead = score.part("lead", synth="triangle", envelope="pluck")
+
+   for chord in chords:
+       rhythm.add(chord, Duration.WHOLE)
+
+   for note_name in blues.note_names[:-1]:  # walk up the scale
+       lead.add(f"{note_name}4", Duration.HALF)
+
+   # 4. See it as tablature
+   print(lead.to_tab())
+
+   # 5. See the scale on the fretboard
+   fb = Fretboard.guitar()
+   print(fb.scale_diagram(blues, frets=12))
+
+Nashville numbers tell you *what chords to play*. The blues scale tells you *what notes to solo with*. Tablature tells you *where to put your fingers*. Together, they're everything you need to play the blues.

docs/guide/scales.rst

@@ -269,6 +269,23 @@ easy:
    ['G major', 'A minor', 'B minor', 'C major', 'D major', 'E minor', 'F# diminished']
    >>> key.seventh_chords
    ['G major 7th', 'A minor 7th', 'B minor 7th', 'C major 7th', 'D dominant 7th', 'E minor 7th', 'F# half-diminished 7th']
+
+Build a seventh chord on any individual degree with ``seventh()``:
+
+.. code-block:: pycon
+
+   >>> key.seventh(0)   # I7
+   G major 7th
+   >>> key.seventh(4)   # V7
+   D dominant 7th
+   >>> key.seventh(6)   # vii7
+   F# half-diminished 7th
+
+This is the single-degree version of ``seventh_chords`` — useful when
+you need one specific chord rather than the full list.
+
+.. code-block:: pycon
+
    >>> Key.detect("C", "E", "G", "A", "D")
    C major
 
@@ -440,7 +457,16 @@ alternative scales to improvise over:
    >>> Scale.recommend("C", "Eb", "F", "Gb", "G", "Bb", top=3)
    [('C', 'blues', 1.0), ...]
 
-Chromatic scales are deprioritized since they match everything.
+How it works: ``recommend()`` tests your notes against every scale in
+every key (all 12 tonics times all scale types in the Western system).
+Each candidate is scored using ``fitness()`` — the fraction of your notes
+that belong to that scale (1.0 = perfect match). Results are ranked by
+fitness, with chromatic scales deprioritized since they match everything.
+Scales whose length is closer to the number of input notes are preferred
+when fitness scores tie.
+
+Returns a list of ``(tonic, scale_name, fitness)`` tuples. Pass ``top=``
+to control how many results you get back (default 5).
 
 Parallel Modes
 ~~~~~~~~~~~~~~

docs/guide/tones.rst

@@ -357,6 +357,32 @@ every tone knows its enharmonic spelling:
    >>> Tone.from_string("C4", system="western").enharmonic is None
    True
 
+Accidental Properties
+~~~~~~~~~~~~~~~~~~~~~
+
+Check whether a tone is natural, sharp, or flat:
+
+.. code-block:: pycon
+
+   >>> c = Tone.from_string("C4", system="western")
+   >>> c.is_natural
+   True
+   >>> c.is_sharp
+   False
+
+   >>> cs = Tone.from_string("C#4", system="western")
+   >>> cs.is_sharp
+   True
+   >>> cs.is_natural
+   False
+
+   >>> bb = Tone.from_string("Bb4", system="western")
+   >>> bb.is_flat
+   True
+
+Useful for filtering — for example, finding all natural notes in a
+scale, or counting accidentals in a melody.
+
 Extended Enharmonics
 ~~~~~~~~~~~~~~~~~~~~
 

docs/index.rst

@@ -118,6 +118,7 @@ What's Inside
    guide/scales
    guide/chords
    guide/fretboard
+   guide/nashville-blues-tabs
    guide/systems
    guide/sequencing
    guide/synths

examples/chord_charts.py

@@ -1,17 +1,8 @@
-from pytheory import Tone, Fretboard, CHARTS
+from pytheory import Fretboard, CHARTS
 
-# Create standard tuning (from high E to low E)
-standard_tuning = [
-    Tone.from_string("E4"),  # High E
-    Tone.from_string("B3"),  # B
-    Tone.from_string("G3"),  # G
-    Tone.from_string("D3"),  # D
-    Tone.from_string("A2"),  # A
-    Tone.from_string("E2"),  # Low E
-]
-
-# Create fretboard with standard tuning
-fretboard = Fretboard(tones=standard_tuning)
+# Standard guitar fretboard. Since v0.43.0 fingerings read low to high
+# (low E first) by default — exactly how tab is conventionally written.
+fretboard = Fretboard.guitar()
 
 # Define flat to sharp note mappings (updated to include all possible flats)
 flat_to_sharp = {"Ab": "G#", "Bb": "A#", "Db": "C#", "Eb": "D#", "Gb": "F#"}
@@ -26,34 +17,6 @@ print("Standard Guitar Chord Charts:")
 print("-" * 30)
 
 
-def fingering_to_tab(fingering):
-    if not fingering:
-        return ""
-
-    # Create 6 strings of dashes, representing the guitar strings
-    strings = ["-" * 15 for _ in range(6)]
-
-    # For each string (starting from high E)
-    for string_num, fret in enumerate(fingering):
-        if fret is not None:
-            # Place the fret number at the correct position
-            if fret == 0:
-                strings[string_num] = "0" + strings[string_num][1:]
-            else:
-                strings[string_num] = (
-                    "-" * (fret - 1) + str(fret) + strings[string_num][fret:]
-                )
-
-    # Combine strings with newlines, and add string names
-    tab = "e|" + strings[0] + "\n"
-    tab += "B|" + strings[1] + "\n"
-    tab += "G|" + strings[2] + "\n"
-    tab += "D|" + strings[3] + "\n"
-    tab += "A|" + strings[4] + "\n"
-    tab += "E|" + strings[5] + "\n"
-    return tab
-
-
 for chord_name in all_chords:
     # Store original chord name for lookup
     lookup_name = chord_name
@@ -74,7 +37,7 @@ for chord_name in all_chords:
     try:
         fingering = chord.fingering(fretboard=fretboard)
         print(f"\n{display_name}:")
-        print(fingering_to_tab(fingering))
+        print(fingering.tab())
     except Exception as e:
         print(f"{display_name}: Unable to calculate fingering - {str(e)}")
         # Add more detailed debug information

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pytheory"
-version = "0.42.1"
+version = "0.43.0"
 description = "Music Theory for Humans"
 readme = "README.md"
 license = "MIT"

pytheory/__init__.py

@@ -1,6 +1,6 @@
 """PyTheory: Music Theory for Humans."""
 
-__version__ = "0.42.1"
+__version__ = "0.43.0"
 
 from .tones import Tone, Interval
 from .systems import System, SYSTEMS, TET

pytheory/charts.py

@@ -13,7 +13,8 @@ STANDARD_GUITAR_TUNING = ("E4", "B3", "G3", "D3", "A2", "E2")
 
 # Curated override fingerings for common guitar chords in standard tuning.
 # Key: chord name, Value: tuple of fret positions (-1 = muted string).
-# Order is high-to-low (matching Fretboard.guitar() string order).
+# Order is canonical high-to-low (high-E first); Fingering re-orients these
+# to the board's display orientation (low-to-high by default since v0.43.0).
 GUITAR_OVERRIDES = {
     "C":    (0, 1, 0, 2, 3, -1),
     "D":    (2, 3, 2, 0, -1, -1),
@@ -60,11 +61,16 @@ class Fingering:
         3
     """
 
-    def __init__(self, positions: tuple, string_names: tuple[str, ...], *, fretboard=None) -> None:
-        self.positions = tuple(positions)
+    def __init__(self, positions: tuple, string_names: tuple[str, ...], *,
+                 fretboard=None, high_to_low: bool = True) -> None:
+        # `positions` / `string_names` arrive in canonical (high-to-low)
+        # order; `high_to_low` controls only how they're presented. The
+        # default (True) keeps standalone construction high-to-low.
+        self.high_to_low = high_to_low
+        self._positions = tuple(positions)
         self._fretboard = fretboard
-        # Disambiguate duplicate names: for standard guitar tuning
-        # (high-to-low), the first occurrence of a duplicate becomes
+        # Disambiguate duplicate names in canonical (high-to-low) order:
+        # the first (higher-pitched) occurrence of a duplicate becomes
         # lowercase (e.g. high E → 'e') while the last keeps uppercase.
         from collections import Counter
         name_counts = Counter(string_names)
@@ -77,8 +83,22 @@ class Fingering:
             else:
                 unique_names.append(name)
 
-        self.string_names = tuple(unique_names)
-        self._map = dict(zip(self.string_names, self.positions))
+        self._string_names = tuple(unique_names)
+        self._map = dict(zip(self._string_names, self._positions))
+
+    def _orient(self, seq):
+        """Re-orient a canonical (high-to-low) sequence for display."""
+        return tuple(seq) if self.high_to_low else tuple(reversed(seq))
+
+    @property
+    def positions(self) -> tuple:
+        """Fret positions in this fingering's orientation (low-to-high by default)."""
+        return self._orient(self._positions)
+
+    @property
+    def string_names(self) -> tuple:
+        """String names in this fingering's orientation (low-to-high by default)."""
+        return self._orient(self._string_names)
 
     def __repr__(self) -> str:
         pairs = ", ".join(
@@ -114,11 +134,12 @@ class Fingering:
         """
         if self._fretboard is None:
             raise ValueError("Cannot resolve tones without a fretboard reference.")
-        tones = []
-        for pos, tone in zip(self.positions, self._fretboard.tones):
-            if pos is not None:
-                tones.append(tone.add(pos))
-        return tones
+        # Zip canonical positions with canonical open tones so they always
+        # align regardless of orientation, then present in display order.
+        tones = [tone.add(pos)
+                 for pos, tone in zip(self._positions, self._fretboard._tones)
+                 if pos is not None]
+        return tones if self.high_to_low else list(reversed(tones))
 
     def to_chord(self, fretboard=None) -> "Chord":
         """Apply this fingering to a fretboard, returning a Chord.
@@ -131,10 +152,9 @@ class Fingering:
         fb = fretboard or self._fretboard
         if fb is None:
             raise ValueError("No fretboard provided.")
-        tones = []
-        for pos, tone in zip(self.positions, fb.tones):
-            if pos is not None:
-                tones.append(tone.add(pos))
+        tones = [tone.add(pos)
+                 for pos, tone in zip(self._positions, fb._tones)
+                 if pos is not None]
         return Chord(tones=tones)
 
     def identify(self) -> Optional[str]:
@@ -151,12 +171,12 @@ class Fingering:
             >>> fb = Fretboard.guitar()
             >>> print(fb.chord("C").tab())
             C
-            e|--0--
-            B|--1--
-            G|--0--
-            D|--2--
+            E|--x--
             A|--3--
-            E|--0--
+            D|--2--
+            G|--0--
+            B|--1--
+            e|--0--
         """
         if self._fretboard is None:
             raise ValueError("Cannot render tab without a fretboard reference.")
@@ -306,7 +326,7 @@ class NamedChord:
             return tuple(fingerings)
 
         fingering = []
-        for i, tone in enumerate(fretboard.tones):
+        for i, tone in enumerate(fretboard._tones):
             frets = find_fingerings(tone)
             # Always allow muting as an option
             if frets:
@@ -335,8 +355,13 @@ class NamedChord:
         return tuple(itertools.product(*self._possible_fingerings(fretboard=fretboard)))
 
     def _cache_key(self, fretboard):
-        """Return a hashable key for memoization."""
-        return (self.name, tuple(t.full_name for t in fretboard.tones))
+        """Return a hashable key for memoization.
+
+        Keyed on canonical tones plus orientation so the two display
+        orderings of the same board don't collide in the result caches.
+        """
+        return (self.name, tuple(t.full_name for t in fretboard._tones),
+                fretboard.high_to_low)
 
     def fingering(self, *, fretboard, multiple=False):
         # Check cache first
@@ -348,19 +373,22 @@ class NamedChord:
             if key in _fingering_cache:
                 return _fingering_cache[key]
 
-        # Check for curated guitar chord overrides in standard tuning
-        tuning = tuple(t.full_name for t in fretboard.tones)
+        # Check for curated guitar chord overrides in standard tuning.
+        # Overrides are written in canonical (high-to-low) order.
+        tuning = tuple(t.full_name for t in fretboard._tones)
         if tuning == STANDARD_GUITAR_TUNING and self.name in GUITAR_OVERRIDES:
-            string_names = tuple(t.name for t in fretboard.tones)
+            string_names = tuple(t.name for t in fretboard._tones)
             override = GUITAR_OVERRIDES[self.name]
             if not multiple:
-                result = Fingering(self.fix_fingering(override), string_names, fretboard=fretboard)
+                result = Fingering(self.fix_fingering(override), string_names,
+                                   fretboard=fretboard, high_to_low=fretboard.high_to_low)
                 if len(_fingering_cache) >= _CACHE_MAX_SIZE:
                     _fingering_cache.clear()
                 _fingering_cache[key] = result
                 return result
             else:
-                result = (Fingering(self.fix_fingering(override), string_names, fretboard=fretboard),)
+                result = (Fingering(self.fix_fingering(override), string_names,
+                                    fretboard=fretboard, high_to_low=fretboard.high_to_low),)
                 if len(_fingering_multi_cache) >= _CACHE_MAX_SIZE:
                     _fingering_multi_cache.clear()
                 _fingering_multi_cache[key] = result
@@ -390,7 +418,7 @@ class NamedChord:
             sounding_names = set()
             for i, f in enumerate(fingering):
                 if f != -1:
-                    sounding_names.add(fretboard.tones[i].add(f).name)
+                    sounding_names.add(fretboard._tones[i].add(f).name)
             required = set(t.name for t in self.acceptable_tones)
             missing = required - sounding_names
             score -= len(missing) * 5.0
@@ -433,12 +461,13 @@ class NamedChord:
             if fingers_needed > 4:
                 score -= (fingers_needed - 4) * 5.0
 
-            # Reward root in bass — the lowest sounding string
+            # Reward root in bass — the lowest sounding string. `fingering`
+            # is canonical (high-to-low), so the last index is the bass.
             for i in range(len(fingering) - 1, -1, -1):
                 f = fingering[i]
                 if f == -1:
                     continue
-                bass_tone = fretboard.tones[i].add(f)
+                bass_tone = fretboard._tones[i].add(f)
                 if bass_tone.name == self.tone.name:
                     score += 4.0
                 else:
@@ -467,17 +496,20 @@ class NamedChord:
                 if s == max_score:
                     yield possible_fingering
 
-        string_names = tuple(t.name for t in fretboard.tones)
+        string_names = tuple(t.name for t in fretboard._tones)
         best_fingerings = tuple([g for g in gen()])
         if not multiple:
-            result = Fingering(self.fix_fingering(best_fingerings[0]), string_names, fretboard=fretboard)
+            result = Fingering(self.fix_fingering(best_fingerings[0]), string_names,
+                               fretboard=fretboard, high_to_low=fretboard.high_to_low)
             # Bounded cache: clear entirely if over limit
             if len(_fingering_cache) >= _CACHE_MAX_SIZE:
                 _fingering_cache.clear()
             _fingering_cache[key] = result
             return result
         else:
-            result = tuple([Fingering(self.fix_fingering(f), string_names, fretboard=fretboard) for f in best_fingerings])
+            result = tuple([Fingering(self.fix_fingering(f), string_names,
+                                      fretboard=fretboard, high_to_low=fretboard.high_to_low)
+                            for f in best_fingerings])
             # Bounded cache: clear entirely if over limit
             if len(_fingering_multi_cache) >= _CACHE_MAX_SIZE:
                 _fingering_multi_cache.clear()
@@ -491,18 +523,21 @@ class NamedChord:
 
             >>> print(CHARTS["western"]["C"].tab(fretboard=Fretboard.guitar()))
             C
-            e|--0--
-            B|--1--
-            G|--0--
-            D|--2--
+            E|--x--
             A|--3--
-            E|--0--
+            D|--2--
+            G|--0--
+            B|--1--
+            e|--0--
         """
         fingering = self.fingering(fretboard=fretboard)
-        string_names = [t.name for t in fretboard.tones]
+        # Use the fingering's oriented, disambiguated string names/positions
+        # so the tab honors the fretboard's orientation.
+        string_names = fingering.string_names
+        positions = fingering.positions
         lines = [self.name]
         max_name = max(len(n) for n in string_names)
-        for i, (name, fret) in enumerate(zip(string_names, fingering)):
+        for name, fret in zip(string_names, positions):
             fret_str = "x" if fret is None else str(fret)
             lines.append(f"{name:>{max_name}}|--{fret_str}--")
         return "\n".join(lines)

pytheory/chords.py

@@ -1352,14 +1352,63 @@ class Chord:
 
 
 class Fretboard:
-    def __init__(self, *, tones: list[Tone]) -> None:
+    def __init__(self, *, tones: list[Tone], high_to_low: bool = False,
+                 _canonical: bool = False) -> None:
         """Initialize a Fretboard from a list of open-string Tone objects.
 
         Args:
             tones: A list of :class:`Tone` instances representing the
-                open strings (high to low).
+                open strings. By default these are read **low to high**
+                (low string first) — pass ``high_to_low=True`` if your
+                list runs high to low instead.
+            high_to_low: Orientation of this fretboard. When ``False``
+                (the default since v0.43.0), strings and fingerings read
+                low to high; when ``True``, they read high to low (the
+                pre-0.43 behavior).
+            _canonical: Internal flag — when ``True``, *tones* are already
+                in canonical (high-to-low) order and are stored as-is.
+                Used by the instrument presets.
         """
-        self.tones = tones
+        self.high_to_low = high_to_low
+        # Internally we always store strings high-to-low; this keeps the
+        # fingering scorer and chord-override tables (which assume that
+        # order) untouched. User-facing access is re-oriented on the way out.
+        if _canonical or high_to_low:
+            self._tones = list(tones)
+        else:
+            self._tones = list(reversed(tones))
+
+    def _orient(self, seq):
+        """Re-orient a canonical (high-to-low) sequence for display.
+
+        Returns *seq* unchanged when this board reads high-to-low, or
+        reversed when it reads low-to-high. Self-inverse, so it also maps
+        user-supplied (oriented) input back to canonical order.
+        """
+        return list(seq) if self.high_to_low else list(reversed(seq))
+
+    @property
+    def tones(self) -> list[Tone]:
+        """The open-string tones in this board's orientation.
+
+        Low-to-high by default; high-to-low when ``high_to_low=True``.
+        """
+        return self._orient(self._tones)
+
+    @classmethod
+    def _from_canonical(cls, tone_strings, high_to_low: bool = False) -> Fretboard:
+        """Build a board from canonical (high-to-low) tone-name strings.
+
+        Used by the instrument presets, whose tunings are written in the
+        conventional high-to-low order. *high_to_low* sets only the
+        board's display orientation.
+        """
+        from .tones import Tone
+        return cls(
+            tones=[Tone.from_string(t, system="western") for t in tone_strings],
+            high_to_low=high_to_low,
+            _canonical=True,
+        )
 
     def __repr__(self) -> str:
         l = tuple([tone.full_name for tone in self.tones])
@@ -1391,7 +1440,11 @@ class Fretboard:
         Returns:
             A new Fretboard with all strings raised by ``fret`` semitones.
         """
-        return Fretboard(tones=[t.add(fret) for t in self.tones])
+        return Fretboard(
+            tones=[t.add(fret) for t in self._tones],
+            high_to_low=self.high_to_low,
+            _canonical=True,
+        )
 
     def __iter__(self) -> Iterator[Tone]:
         """Iterate over the open-string tones of this fretboard."""
@@ -1399,7 +1452,7 @@ class Fretboard:
 
     def __len__(self) -> int:
         """Return the number of strings on this fretboard."""
-        return len(self.tones)
+        return len(self._tones)
 
     INSTRUMENTS = [
         "guitar", "twelve_string", "bass", "ukulele",
@@ -1423,84 +1476,76 @@ class Fretboard:
     }
 
     @classmethod
-    def guitar(cls, tuning: Union[str, tuple[str, ...]] = "standard", capo: int = 0) -> Fretboard:
+    def guitar(cls, tuning: Union[str, tuple[str, ...]] = "standard", capo: int = 0,
+               high_to_low: bool = False) -> Fretboard:
         """Guitar with the given tuning and optional capo.
 
         Args:
-            tuning: Tuning name or tuple of tone strings (high to low).
+            tuning: Tuning name, or a tuple of tone strings. A custom
+                tuple is read **low to high** by default (pass
+                ``high_to_low=True`` to give it high to low instead).
                 Built-in tunings: standard, drop d, open g, open d,
                 open e, open a, dadgad, half step down.
             capo: Fret number for the capo (0 = no capo). Raises all
                 strings by this many semitones.
+            high_to_low: When ``True``, the resulting board reads high to
+                low (pre-0.43 behavior); otherwise low to high.
         """
         from .tones import Tone
         if isinstance(tuning, str):
-            tuning = cls.TUNINGS[tuning]
-        fb = cls(tones=[Tone.from_string(t, system="western") for t in tuning])
+            # Built-in tunings are defined canonically (high to low).
+            canonical = [Tone.from_string(t, system="western") for t in cls.TUNINGS[tuning]]
+            fb = cls(tones=canonical, high_to_low=high_to_low, _canonical=True)
+        else:
+            # A user-supplied tuple is in the board's orientation.
+            fb = cls(tones=[Tone.from_string(t, system="western") for t in tuning],
+                     high_to_low=high_to_low)
         if capo:
             fb = fb.capo(capo)
         return fb
 
     @classmethod
-    def bass(cls, five_string: bool = False) -> Fretboard:
+    def bass(cls, five_string: bool = False, high_to_low: bool = False) -> Fretboard:
         """Standard bass guitar tuning.
 
         Args:
             five_string: If True, adds a low B string (B0).
+            high_to_low: When ``True``, the board reads high to low.
         """
-        from .tones import Tone
         strings = ["G2", "D2", "A1", "E1"]
         if five_string:
             strings.append("B0")
-        return cls(tones=[Tone.from_string(t, system="western") for t in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     @classmethod
-    def ukulele(cls) -> Fretboard:
+    def ukulele(cls, high_to_low: bool = False) -> Fretboard:
         """Standard ukulele tuning (A4 E4 C4 G4).
 
         Re-entrant tuning: the G4 string is higher than C4.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("E4", system="western"),
-            Tone.from_string("C4", system="western"),
-            Tone.from_string("G4", system="western"),
-        ])
+        return cls._from_canonical(["A4", "E4", "C4", "G4"], high_to_low)
 
     @classmethod
-    def mandolin(cls) -> Fretboard:
+    def mandolin(cls, high_to_low: bool = False) -> Fretboard:
         """Standard mandolin tuning (E5 A4 D4 G3).
 
         Tuned in fifths, same as a violin but one octave relationship.
         Strings are typically doubled (paired courses).
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("E5", system="western"),
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("D4", system="western"),
-            Tone.from_string("G3", system="western"),
-        ])
+        return cls._from_canonical(["E5", "A4", "D4", "G3"], high_to_low)
 
     @classmethod
-    def mandola(cls) -> Fretboard:
+    def mandola(cls, high_to_low: bool = False) -> Fretboard:
         """Standard mandola tuning (A4 D4 G3 C3).
 
         The mandola (or tenor mandola) is to the mandolin what the
         viola is to the violin — a fifth lower, with a warmer,
         darker tone. Tuned in fifths like all the mandolin family.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("D4", system="western"),
-            Tone.from_string("G3", system="western"),
-            Tone.from_string("C3", system="western"),
-        ])
+        return cls._from_canonical(["A4", "D4", "G3", "C3"], high_to_low)
 
     @classmethod
-    def octave_mandolin(cls) -> Fretboard:
+    def octave_mandolin(cls, high_to_low: bool = False) -> Fretboard:
         """Octave mandolin tuning (E4 A3 D3 G2).
 
         Also called the octave mandola in European terminology.
@@ -1508,84 +1553,57 @@ class Fretboard:
         family's cello-to-violin relationship. Popular in Irish
         and Celtic folk music.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("E4", system="western"),
-            Tone.from_string("A3", system="western"),
-            Tone.from_string("D3", system="western"),
-            Tone.from_string("G2", system="western"),
-        ])
+        return cls._from_canonical(["E4", "A3", "D3", "G2"], high_to_low)
 
     @classmethod
-    def mandocello(cls) -> Fretboard:
+    def mandocello(cls, high_to_low: bool = False) -> Fretboard:
         """Mandocello tuning (A3 D3 G2 C2).
 
         The bass of the mandolin family. Tuned like a cello — an
         octave below the mandola. Rare but beautiful; used in
         mandolin orchestras.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A3", system="western"),
-            Tone.from_string("D3", system="western"),
-            Tone.from_string("G2", system="western"),
-            Tone.from_string("C2", system="western"),
-        ])
+        return cls._from_canonical(["A3", "D3", "G2", "C2"], high_to_low)
 
     @classmethod
-    def violin(cls) -> Fretboard:
+    def violin(cls, high_to_low: bool = False) -> Fretboard:
         """Standard violin tuning (E5 A4 D4 G3).
 
         Tuned in perfect fifths. The violin has no frets — intonation
         is continuous, allowing vibrato and microtonal inflections
         not possible on fretted instruments.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("E5", system="western"),
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("D4", system="western"),
-            Tone.from_string("G3", system="western"),
-        ])
+        return cls._from_canonical(["E5", "A4", "D4", "G3"], high_to_low)
 
     @classmethod
-    def viola(cls) -> Fretboard:
+    def viola(cls, high_to_low: bool = False) -> Fretboard:
         """Standard viola tuning (A4 D4 G3 C3).
 
         A perfect fifth below the violin. The viola's darker, warmer
         tone comes from its larger body and lower register.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("D4", system="western"),
-            Tone.from_string("G3", system="western"),
-            Tone.from_string("C3", system="western"),
-        ])
+        return cls._from_canonical(["A4", "D4", "G3", "C3"], high_to_low)
 
     @classmethod
-    def cello(cls) -> Fretboard:
+    def cello(cls, high_to_low: bool = False) -> Fretboard:
         """Standard cello tuning (A3 D3 G2 C2).
 
         An octave below the viola. Tuned in fifths. The cello spans
         the range of the human voice — tenor through bass.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A3", system="western"),
-            Tone.from_string("D3", system="western"),
-            Tone.from_string("G2", system="western"),
-            Tone.from_string("C2", system="western"),
-        ])
+        return cls._from_canonical(["A3", "D3", "G2", "C2"], high_to_low)
 
     @classmethod
-    def banjo(cls, tuning: Union[str, tuple[str, ...]] = "open g") -> Fretboard:
+    def banjo(cls, tuning: Union[str, tuple[str, ...]] = "open g",
+              high_to_low: bool = False) -> Fretboard:
         """Banjo with the given tuning.
 
         Args:
             tuning: ``"open g"`` (default, bluegrass) or ``"open d"``
                 (old-time, clawhammer). The 5th string is a high
-                drone — a defining feature of the banjo sound.
+                drone — a defining feature of the banjo sound. A custom
+                tuple is read low to high unless ``high_to_low=True``.
+            high_to_low: When ``True``, the board reads high to low.
 
         Standard open G: G4 D3 G3 B3 D4 (5th string is the short
         high G4 drone).
@@ -1597,11 +1615,12 @@ class Fretboard:
             "double c": ("D4", "C4", "G3", "C3", "G4"),
         }
         if isinstance(tuning, str):
-            tuning = tunings[tuning]
-        return cls(tones=[Tone.from_string(t, system="western") for t in tuning])
+            return cls._from_canonical(tunings[tuning], high_to_low)
+        return cls(tones=[Tone.from_string(t, system="western") for t in tuning],
+                   high_to_low=high_to_low)
 
     @classmethod
-    def double_bass(cls) -> Fretboard:
+    def double_bass(cls, high_to_low: bool = False) -> Fretboard:
         """Standard double bass (upright bass) tuning (G2 D2 A1 E1).
 
         The largest and lowest-pitched bowed string instrument in the
@@ -1611,16 +1630,10 @@ class Fretboard:
 
         The 5-string double bass adds a low B0 or C1.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("G2", system="western"),
-            Tone.from_string("D2", system="western"),
-            Tone.from_string("A1", system="western"),
-            Tone.from_string("E1", system="western"),
-        ])
+        return cls._from_canonical(["G2", "D2", "A1", "E1"], high_to_low)
 
     @classmethod
-    def harp(cls) -> Fretboard:
+    def harp(cls, high_to_low: bool = False) -> Fretboard:
         """Concert harp strings — 47 strings spanning C1 to G7.
 
         The pedal harp has 7 strings per octave (one per note name),
@@ -1630,7 +1643,6 @@ class Fretboard:
         This returns the full set of 47 strings in the default
         Cb (enharmonic B) tuning.
         """
-        from .tones import Tone
         # 47 strings: C1 to G7, one per diatonic note
         notes = ["C", "D", "E", "F", "G", "A", "B"]
         strings = []
@@ -1643,30 +1655,33 @@ class Fretboard:
             else:
                 continue
             break
-        # Harp strings are high to low
+        # Canonical (high to low)
         strings.reverse()
-        return cls(tones=[Tone.from_string(s, system="western") for s in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     @classmethod
-    def pedal_steel(cls) -> Fretboard:
+    def pedal_steel(cls, high_to_low: bool = False) -> Fretboard:
         """Pedal steel guitar — E9 Nashville tuning (10 strings).
 
         The standard tuning for country music. The pedal steel has
         foot pedals and knee levers that change string pitches during
         play, enabling its signature swooping, crying sound.
         """
-        from .tones import Tone
-        # E9 Nashville tuning (high to low)
+        # E9 Nashville tuning (canonical: high to low)
         strings = ["F#4", "D#4", "G#3", "E3", "B3", "G#3",
                     "F#3", "E3", "D3", "B2"]
-        return cls(tones=[Tone.from_string(s, system="western") for s in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     @classmethod
-    def bouzouki(cls, variant: Union[str, tuple[str, ...]] = "irish") -> Fretboard:
+    def bouzouki(cls, variant: Union[str, tuple[str, ...]] = "irish",
+                 high_to_low: bool = False) -> Fretboard:
         """Bouzouki tuning.
 
         Args:
             variant: ``"irish"`` (default, GDAD) or ``"greek"`` (CFAD).
+                A custom tuple is read low to high unless
+                ``high_to_low=True``.
+            high_to_low: When ``True``, the board reads high to low.
 
         The Irish bouzouki is a staple of Celtic music, usually tuned
         in unison or octave pairs. The Greek bouzouki traditionally
@@ -1678,11 +1693,12 @@ class Fretboard:
             "greek": ("D4", "A3", "F3", "C3"),
         }
         if isinstance(variant, str):
-            variant = tunings[variant]
-        return cls(tones=[Tone.from_string(t, system="western") for t in variant])
+            return cls._from_canonical(tunings[variant], high_to_low)
+        return cls(tones=[Tone.from_string(t, system="western") for t in variant],
+                   high_to_low=high_to_low)
 
     @classmethod
-    def oud(cls) -> Fretboard:
+    def oud(cls, high_to_low: bool = False) -> Fretboard:
         """Standard Arabic oud tuning (C4 G3 D3 A2 G2 C2).
 
         The oud is the ancestor of the European lute and the defining
@@ -1691,12 +1707,11 @@ class Fretboard:
         essential to maqam performance. 6 courses (11 strings),
         typically tuned in fourths.
         """
-        from .tones import Tone
         strings = ["C4", "G3", "D3", "A2", "G2", "C2"]
-        return cls(tones=[Tone.from_string(t, system="western") for t in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     @classmethod
-    def sitar(cls) -> Fretboard:
+    def sitar(cls, high_to_low: bool = False) -> Fretboard:
         """Sitar main playing strings (approximation).
 
         The sitar typically has 6-7 main strings and 11-13 sympathetic
@@ -1706,14 +1721,13 @@ class Fretboard:
         Main strings: Sa Sa Pa Sa Re Sa Ma (approximated in 12-TET).
         Represented here as the most common Ravi Shankar school tuning.
         """
-        from .tones import Tone
         # Common Ravi Shankar tuning mapped to Western notes
         # (sitar is tuned relative to Sa, typically C# or D)
         strings = ["C4", "C3", "G3", "C3", "D3", "C2", "F2"]
-        return cls(tones=[Tone.from_string(t, system="western") for t in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     @classmethod
-    def shamisen(cls) -> Fretboard:
+    def shamisen(cls, high_to_low: bool = False) -> Fretboard:
         """Standard shamisen tuning — honchoshi (C4 G3 C3).
 
         The shamisen is a 3-stringed Japanese instrument played with
@@ -1723,15 +1737,10 @@ class Fretboard:
         - niagari (二上り): root-5th-2nd (raises 2nd string)
         - sansagari (三下り): root-5th-b7th (lowers 3rd string)
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("C4", system="western"),
-            Tone.from_string("G3", system="western"),
-            Tone.from_string("C3", system="western"),
-        ])
+        return cls._from_canonical(["C4", "G3", "C3"], high_to_low)
 
     @classmethod
-    def erhu(cls) -> Fretboard:
+    def erhu(cls, high_to_low: bool = False) -> Fretboard:
         """Standard erhu tuning (A4 D4).
 
         The erhu is a 2-stringed Chinese bowed instrument with a
@@ -1739,14 +1748,10 @@ class Fretboard:
         — the player presses the strings without touching the neck,
         allowing continuous pitch bending.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("D4", system="western"),
-        ])
+        return cls._from_canonical(["A4", "D4"], high_to_low)
 
     @classmethod
-    def charango(cls) -> Fretboard:
+    def charango(cls, high_to_low: bool = False) -> Fretboard:
         """Standard charango tuning (E5 A4 E5 C5 G4).
 
         A small Andean stringed instrument, traditionally made from
@@ -1754,54 +1759,38 @@ class Fretboard:
         — the 3rd course (E5) is the highest pitched, creating the
         charango's bright, sparkling sound.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("E5", system="western"),
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("E5", system="western"),
-            Tone.from_string("C5", system="western"),
-            Tone.from_string("G4", system="western"),
-        ])
+        return cls._from_canonical(["E5", "A4", "E5", "C5", "G4"], high_to_low)
 
     @classmethod
-    def pipa(cls) -> Fretboard:
+    def pipa(cls, high_to_low: bool = False) -> Fretboard:
         """Standard pipa tuning (D4 A3 E3 A2).
 
         The pipa is a 4-stringed Chinese lute with a pear-shaped
         body, dating back over 2000 years. Known for its percussive
         attack and rapid tremolo technique.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("D4", system="western"),
-            Tone.from_string("A3", system="western"),
-            Tone.from_string("E3", system="western"),
-            Tone.from_string("A2", system="western"),
-        ])
+        return cls._from_canonical(["D4", "A3", "E3", "A2"], high_to_low)
 
     @classmethod
-    def balalaika(cls) -> Fretboard:
+    def balalaika(cls, high_to_low: bool = False) -> Fretboard:
         """Standard balalaika prima tuning (A4 E4 E4).
 
         The Russian balalaika has a distinctive triangular body and
         3 strings. The two lower strings are tuned in unison — a
         unique feature that gives it a natural chorus effect.
         """
-        from .tones import Tone
-        return cls(tones=[
-            Tone.from_string("A4", system="western"),
-            Tone.from_string("E4", system="western"),
-            Tone.from_string("E4", system="western"),
-        ])
+        return cls._from_canonical(["A4", "E4", "E4"], high_to_low)
 
     @classmethod
-    def keyboard(cls, keys: int = 88, start: str = "A0") -> Fretboard:
+    def keyboard(cls, keys: int = 88, start: str = "A0",
+                 high_to_low: bool = False) -> Fretboard:
         """Piano or keyboard with the given number of keys.
 
         Args:
             keys: Number of keys (default 88 for a full piano).
                 Common sizes: 25, 37, 49, 61, 76, 88.
             start: The lowest note (default ``"A0"`` for standard piano).
+            high_to_low: When ``True``, the board reads high to low.
 
         A full 88-key piano spans A0 (27.5 Hz) to C8 (4186 Hz) —
         the widest range of any standard acoustic instrument.
@@ -1815,13 +1804,12 @@ class Fretboard:
         """
         from .tones import Tone
         start_tone = Tone.from_string(start, system="western")
-        tones = []
-        for i in range(keys - 1, -1, -1):
-            tones.append(start_tone.add(i))
-        return cls(tones=tones)
+        # Built high-to-low (canonical): highest key first, down to `start`.
+        tones = [start_tone.add(i) for i in range(keys - 1, -1, -1)]
+        return cls(tones=tones, high_to_low=high_to_low, _canonical=True)
 
     @classmethod
-    def lute(cls) -> Fretboard:
+    def lute(cls, high_to_low: bool = False) -> Fretboard:
         """Renaissance lute in G tuning (6 courses).
 
         The European lute was the dominant instrument of the
@@ -1829,21 +1817,19 @@ class Fretboard:
         a major third between the 3rd and 4th courses — the
         same intervallic pattern as a modern guitar.
         """
-        from .tones import Tone
         strings = ["G4", "D4", "A3", "F3", "C3", "G2"]
-        return cls(tones=[Tone.from_string(t, system="western") for t in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     @classmethod
-    def twelve_string(cls) -> Fretboard:
+    def twelve_string(cls, high_to_low: bool = False) -> Fretboard:
         """12-string guitar in standard tuning.
 
         The lower 4 courses are doubled at the octave; the upper 2
         are doubled in unison. This creates the characteristic
         shimmering, chorus-like sound.
 
-        Represented as 12 strings (high to low, pairs together).
+        Represented as 12 strings (canonical: high to low, pairs together).
         """
-        from .tones import Tone
         strings = [
             "E4", "E4",      # 1st course (unison)
             "B3", "B3",      # 2nd course (unison)
@@ -1852,7 +1838,7 @@ class Fretboard:
             "A3", "A2",      # 5th course (octave)
             "E3", "E2",      # 6th course (octave)
         ]
-        return cls(tones=[Tone.from_string(t, system="western") for t in strings])
+        return cls._from_canonical(strings, high_to_low)
 
     def scale_diagram(self, scale, frets: int = 12, chord=None) -> str:
         """Render an ASCII diagram showing where scale notes fall on the neck.
@@ -1927,7 +1913,7 @@ class Fretboard:
 
             >>> fb = Fretboard.guitar()
             >>> fb.chord("G")
-            Fingering(e=3, B=0, G=0, D=0, A=2, E=3)
+            Fingering(E=3, A=2, D=0, G=0, B=0, e=3)
         """
         from .charts import CHARTS
         return CHARTS[system][name].fingering(fretboard=self)
@@ -1945,7 +1931,7 @@ class Fretboard:
 
             >>> fb = Fretboard.guitar()
             >>> fb["G"]
-            Fingering(e=3, B=0, G=0, D=0, A=2, E=3)
+            Fingering(E=3, A=2, D=0, G=0, B=0, e=3)
         """
         return self.chord(name)
 
@@ -1964,12 +1950,12 @@ class Fretboard:
             >>> fb = Fretboard.guitar()
             >>> print(fb.tab("Am"))
             A minor
-            e|--0--
-            B|--1--
-            G|--2--
-            D|--2--
+            E|--x--
             A|--0--
-            E|--0--
+            D|--2--
+            G|--2--
+            B|--1--
+            e|--0--
         """
         return self.chord(name, system=system).tab()
 
@@ -1984,7 +1970,7 @@ class Fretboard:
             >>> fb = Fretboard.guitar()
             >>> chart = fb.chart()
             >>> chart["Am7"]
-            Fingering(e=0, B=1, G=0, D=2, A=0, E=0)
+            Fingering(E=0, A=0, D=2, G=0, B=1, e=0)
         """
         from .charts import charts_for_fretboard, CHARTS
         return charts_for_fretboard(chart=CHARTS[system], fretboard=self)
@@ -2009,13 +1995,16 @@ class Fretboard:
         """
         from .charts import Fingering
 
-        if not len(positions) == len(self.tones):
+        if not len(positions) == len(self._tones):
             raise ValueError(
                 "The number of positions must match the number of tones (strings)."
             )
 
-        string_names = tuple(t.name for t in self.tones)
-        return Fingering(positions, string_names, fretboard=self)
+        # Positions arrive in this board's orientation; canonicalise them
+        # (high-to-low) to match the internal tone order Fingering expects.
+        string_names = tuple(t.name for t in self._tones)
+        return Fingering(self._orient(positions), string_names, fretboard=self,
+                         high_to_low=self.high_to_low)
 
 
 def analyze_progression(chords: list[Chord], key: str = "C", mode: str = "major") -> list[str | None]:

pytheory/rhythm.py

@@ -3706,17 +3706,19 @@ class Part:
             fingering = self._fretboard.chord(chord_name)
 
         # Get the sounding tones (skips muted strings)
-        tones = fingering.tones  # list of Tone objects, high to low
+        tones = fingering.tones
 
         if not tones:
             self.rest(duration)
             return self
 
-        # Order: down strum = low to high (reverse since tones are high-to-low)
+        # Sort by pitch so strum direction is correct regardless of the
+        # fingering's display orientation: down = low to high, up = high to low.
+        low_to_high = sorted(tones, key=lambda t: t.midi)
         if direction == "down":
-            strum_tones = list(reversed(tones))
+            strum_tones = low_to_high
         else:
-            strum_tones = list(tones)
+            strum_tones = list(reversed(low_to_high))
 
         if hasattr(duration, 'value'):
             total_beats = duration.value
@@ -3826,8 +3828,9 @@ class Part:
             open_midis = list(self._TAB_TUNINGS[tuning])
             labels = list(self._TAB_LABELS[tuning])
         elif hasattr(tuning, "tones"):
-            # Fretboard object — tones are high-to-low, reverse for low-to-high
-            fb_tones = list(reversed(tuning.tones))
+            # Fretboard object — sort by pitch so we get low-to-high
+            # regardless of the board's display orientation.
+            fb_tones = sorted(tuning.tones, key=lambda t: t.midi)
             open_midis = [t.midi for t in fb_tones]
             labels = [t.name if len(t.name) <= 2 else t.name[0] for t in fb_tones]
         else:

test_pytheory.py

@@ -482,7 +482,8 @@ def test_fretboard_creation():
         Tone(name="A", octave=2),
         Tone(name="E", octave=2),
     ]
-    fretboard = Fretboard(tones=standard_tuning)
+    # Literal is written high-to-low, so declare that orientation.
+    fretboard = Fretboard(tones=standard_tuning, high_to_low=True)
     assert len(fretboard.tones) == 6
     assert fretboard.tones[0].full_name == "E4"
     assert fretboard.tones[-1].full_name == "E2"
@@ -505,7 +506,8 @@ def guitar_fretboard():
         Tone.from_string("A2"),
         Tone.from_string("E2"),
     ]
-    return Fretboard(tones=tuning)
+    # Literal is written high-to-low, so declare that orientation.
+    return Fretboard(tones=tuning, high_to_low=True)
 
 
 def test_chord_fingering_c(guitar_fretboard):
@@ -1767,28 +1769,32 @@ def test_chord_contains_tone():
 def test_fretboard_guitar():
     fb = Fretboard.guitar()
     assert len(fb) == 6
+    # Low-to-high by default (v0.43.0).
     names = [t.name for t in fb]
-    assert names == ["E", "B", "G", "D", "A", "E"]
+    assert names == ["E", "A", "D", "G", "B", "E"]
+    # high_to_low=True restores the pre-0.43 order.
+    assert [t.name for t in Fretboard.guitar(high_to_low=True)] == \
+        ["E", "B", "G", "D", "A", "E"]
 
 
 def test_fretboard_guitar_octaves():
     fb = Fretboard.guitar()
     octaves = [t.octave for t in fb]
-    assert octaves == [4, 3, 3, 3, 2, 2]
+    assert octaves == [2, 2, 3, 3, 3, 4]
 
 
 def test_fretboard_bass():
     fb = Fretboard.bass()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["G", "D", "A", "E"]
+    assert names == ["E", "A", "D", "G"]
 
 
 def test_fretboard_ukulele():
     fb = Fretboard.ukulele()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["A", "E", "C", "G"]
+    assert names == ["G", "C", "E", "A"]
 
 
 def test_fretboard_iter():
@@ -1821,8 +1827,9 @@ def test_fretboard_ukulele_fingerings():
 def test_fretboard_guitar_drop_d():
     fb = Fretboard.guitar("drop d")
     assert len(fb) == 6
-    assert fb.tones[-1].name == "D"
-    assert fb.tones[-1].octave == 2
+    # Low-to-high: the dropped low D is now the first string.
+    assert fb.tones[0].name == "D"
+    assert fb.tones[0].octave == 2
 
 
 def test_fretboard_guitar_open_g():
@@ -1840,7 +1847,8 @@ def test_fretboard_guitar_custom_tuple():
 def test_fretboard_bass_five_string():
     fb = Fretboard.bass(five_string=True)
     assert len(fb) == 5
-    assert fb.tones[-1].name == "B"
+    # Low-to-high: the added low B is the first string.
+    assert fb.tones[0].name == "B"
 
 
 def test_fretboard_tunings_dict():
@@ -1852,36 +1860,37 @@ def test_fretboard_tunings_dict():
 def test_fretboard_mandolin():
     fb = Fretboard.mandolin()
     assert len(fb) == 4
-    assert fb.tones[0].name == "E"
-    assert fb.tones[-1].name == "G"
+    # Low-to-high.
+    assert fb.tones[0].name == "G"
+    assert fb.tones[-1].name == "E"
 
 
 def test_fretboard_violin():
     fb = Fretboard.violin()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["E", "A", "D", "G"]
+    assert names == ["G", "D", "A", "E"]
 
 
 def test_fretboard_viola():
     fb = Fretboard.viola()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["A", "D", "G", "C"]
+    assert names == ["C", "G", "D", "A"]
 
 
 def test_fretboard_cello():
     fb = Fretboard.cello()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["A", "D", "G", "C"]
-    assert fb.tones[0].octave == 3
+    assert names == ["C", "G", "D", "A"]
+    assert fb.tones[0].octave == 2
 
 
 def test_fretboard_banjo():
     fb = Fretboard.banjo()
     assert len(fb) == 5
-    assert fb.tones[-1].name == "G"  # high drone string
+    assert fb.tones[0].name == "G"  # high drone string (now first, low-to-high)
 
 
 def test_fretboard_banjo_open_d():
@@ -1898,46 +1907,49 @@ def test_fretboard_violin_tuned_in_fifths():
     """Violin strings should be a perfect 5th apart."""
     fb = Fretboard.violin()
     for i in range(len(fb.tones) - 1):
-        interval = fb.tones[i] - fb.tones[i + 1]
+        # Low-to-high: each next string is a 5th higher.
+        interval = fb.tones[i + 1] - fb.tones[i]
         assert interval == 7, f"Strings {i} and {i+1} not a 5th apart"
 
 
 def test_fretboard_octave_mandolin():
     fb = Fretboard.octave_mandolin()
     assert len(fb) == 4
-    assert fb.tones[0].name == "E"
-    assert fb.tones[0].octave == 4
+    assert fb.tones[-1].name == "E"
+    assert fb.tones[-1].octave == 4
 
 
 def test_fretboard_mandocello():
     fb = Fretboard.mandocello()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["A", "D", "G", "C"]
-    assert fb.tones[0].octave == 3
+    assert names == ["C", "G", "D", "A"]
+    assert fb.tones[0].octave == 2
 
 
 def test_fretboard_double_bass():
     fb = Fretboard.double_bass()
     assert len(fb) == 4
     names = [t.name for t in fb]
-    assert names == ["G", "D", "A", "E"]
+    assert names == ["E", "A", "D", "G"]
 
 
 def test_fretboard_double_bass_tuned_in_fourths():
     fb = Fretboard.double_bass()
     for i in range(len(fb.tones) - 1):
-        interval = fb.tones[i] - fb.tones[i + 1]
+        # Low-to-high: each next string is a 4th higher.
+        interval = fb.tones[i + 1] - fb.tones[i]
         assert interval == 5, f"Strings {i} and {i+1} not a 4th apart"
 
 
 def test_fretboard_harp():
     fb = Fretboard.harp()
     assert len(fb) == 47
-    assert fb.tones[0].name == "G"
-    assert fb.tones[0].octave == 7
-    assert fb.tones[-1].name == "C"
-    assert fb.tones[-1].octave == 1
+    # Low-to-high.
+    assert fb.tones[0].name == "C"
+    assert fb.tones[0].octave == 1
+    assert fb.tones[-1].name == "G"
+    assert fb.tones[-1].octave == 7
 
 
 def test_fretboard_pedal_steel():
@@ -1950,7 +1962,7 @@ def test_mandolin_family_fifths():
     for name in ["mandolin", "mandola", "octave_mandolin", "mandocello"]:
         fb = getattr(Fretboard, name)()
         for i in range(len(fb.tones) - 1):
-            interval = fb.tones[i] - fb.tones[i + 1]
+            interval = fb.tones[i + 1] - fb.tones[i]
             assert interval == 7, f"{name} strings {i},{i+1} not a 5th apart"
 
 
@@ -1982,7 +1994,7 @@ def test_fretboard_shamisen():
 def test_fretboard_erhu():
     fb = Fretboard.erhu()
     assert len(fb) == 2
-    assert fb.tones[0] - fb.tones[1] == 7  # tuned in 5ths
+    assert fb.tones[1] - fb.tones[0] == 7  # tuned in 5ths (low-to-high)
 
 
 def test_fretboard_bouzouki_irish():
@@ -2003,8 +2015,8 @@ def test_fretboard_charango():
 def test_fretboard_balalaika():
     fb = Fretboard.balalaika()
     assert len(fb) == 3
-    # Two unison strings
-    assert fb.tones[1].name == fb.tones[2].name
+    # Two unison strings (now the lowest two, low-to-high)
+    assert fb.tones[0].name == fb.tones[1].name
 
 
 def test_fretboard_lute():
@@ -2030,8 +2042,9 @@ def test_keyboard_88():
 def test_keyboard_25():
     kb = Fretboard.keyboard(25, "C3")
     assert len(kb) == 25
-    assert kb.tones[-1].name == "C"
-    assert kb.tones[-1].octave == 3
+    # Low-to-high: the start note is now the first key.
+    assert kb.tones[0].name == "C"
+    assert kb.tones[0].octave == 3
 
 
 def test_keyboard_custom():
@@ -2039,6 +2052,60 @@ def test_keyboard_custom():
     assert len(kb) == 61
 
 
+# ── Fingering orientation (low-to-high default, v0.43.0) ─────────────────────
+
+def test_chord_low_to_high_default():
+    """By default, chord fingerings read low-to-high (low E first)."""
+    fb = Fretboard.guitar()
+    g = fb.chord("G")
+    assert g.string_names == ("E", "A", "D", "G", "B", "e")
+    assert g.positions == (3, 2, 0, 0, 0, 3)
+
+
+def test_chord_high_to_low_opt_out():
+    """high_to_low=True restores the pre-0.43 high-to-low order."""
+    fb = Fretboard.guitar(high_to_low=True)
+    g = fb.chord("G")
+    assert g.string_names == ("e", "B", "G", "D", "A", "E")
+    assert g.positions == (3, 0, 0, 0, 2, 3)
+
+
+def test_orientation_is_a_reversal():
+    """The two orientations are exact reverses of each other."""
+    lo = Fretboard.guitar().chord("Am7")
+    hi = Fretboard.guitar(high_to_low=True).chord("Am7")
+    assert lo.positions == tuple(reversed(hi.positions))
+    # ...and identify to the same chord.
+    assert lo.identify() == hi.identify()
+
+
+def test_manual_fingering_input_orientation():
+    """Manual fret positions are read in the board's orientation."""
+    lo = Fretboard.guitar()
+    hi = Fretboard.guitar(high_to_low=True)
+    # Same physical G voicing, expressed in each orientation.
+    assert lo.fingering(3, 2, 0, 0, 0, 3) == lo.chord("G")
+    assert hi.fingering(3, 0, 0, 0, 2, 3) == hi.chord("G")
+
+
+def test_orientation_cache_no_collision():
+    """The two orientations must not collide in the fingering cache."""
+    lo = Fretboard.guitar().chord("C")
+    hi = Fretboard.guitar(high_to_low=True).chord("C")
+    assert lo.positions != hi.positions
+    assert lo.positions == tuple(reversed(hi.positions))
+
+
+def test_to_tab_orientation_agnostic():
+    """to_tab output is identical regardless of board orientation."""
+    from pytheory import Part
+    notes = ["C4", "E4", "G4"]
+    p_lo = Part("test"); [p_lo.add(n) for n in notes]
+    p_hi = Part("test"); [p_hi.add(n) for n in notes]
+    assert p_lo.to_tab(tuning=Fretboard.guitar()) == \
+        p_hi.to_tab(tuning=Fretboard.guitar(high_to_low=True))
+
+
 # ── Ergonomic integration tests ─────────────────────────────────────────────
 
 def test_ergonomic_workflow():

uv.lock

@@ -690,7 +690,7 @@ wheels = [
 
 [[package]]
 name = "pytheory"
-version = "0.42.1"
+version = "0.43.0"
 source = { editable = "." }
 dependencies = [
     { name = "rich" },