Long-format CSV with three columns: variable , modality , color .

• variable — metadata variable name (factor file) or taxonomic rank name (taxa file). The special value __numeric__ marks a row that assigns a continuous palette to a numeric metadata variable.
• modality — the modality of a categorical variable, the taxon name for a rank, or (when variable = __numeric__ ) the name of the numeric variable.
• color — 7-character hex code #RRGGBB for categorical / taxa rows, or a package::palette string for __numeric__ rows (only viridis and ggthemes continuous palettes are accepted).

Example:

variable,modality,color
treatment,control,#1f77b4
treatment,case,#ff7f0e
Phylum,Firmicutes,#2ca02c
Phylum,Bacteroidetes,#d62728
__numeric__,age,viridis::viridis

Validation: rows with unknown variables, unknown modalities or invalid color codes are dropped silently and reported in the log below each file input. Missing modalities are auto-filled from a deterministic palette.

Round-trip: use Download CSV file buttons to obtain a template seeded with the current color assignments, then edit and re-upload.