A maj9 on Bass (4-String)
Root first, then the colors: every A maj9 tone placed on the EADG neck, ready to walk.
A maj9 spells A – B – C# – E – G#. A bassline treats those notes as a hierarchy — root first for gravity, fifth for stability, then the third and any extensions for color — and the shapes below put each of them under your fingers on the Bass (4-String)'s EADG strings.
Full chords are optional equipment on bass: down low, stacked thirds turn to mud, so the grips that work keep two or three notes — root-fifth, root-tenth, shell voicings — and the arpeggio is how the rest of the chord becomes a line.
Start from the root, play the arpeggio until the sound of A maj9 is in your ears, then loop it against the progressions in A so the tones become choices instead of charts.