Palette and contrast

Say “palette from direction 2” or “do these colors pass contrast?”. The gobanana-palette skill calls extract_palette and puts the colors on the board as swatches.

Where the colors come from

You pick the images, or the agent does:

1. the references you named or liked;
2. otherwise the items in the direction you mean. The Art direction row is a good source: it carries the idea’s color (the weave, the riso inks). Mixing art and UI items from one direction is fine;
3. otherwise every reference on the board.

Up to 12 images per call. The palette has 5 to 9 colors (default 6).

How it is computed

1. The server loads a small thumbnail of each image in memory, from an allowlisted image host.
2. A median cut quantizer finds the main colors. No AI.
3. The thumbnails are dropped as soon as the colors are computed. Nothing is saved.
4. Each color gets a role from its OKLCH lightness and chroma and how much of the images it covers: primary, secondary, accent, neutral, surface, on-surface.
5. Every color is checked against the surface, the on-surface color, white and black.

Ship or explore

Tag	Rule	Use it for
ship	The pair reaches 4.5:1, the WCAG 2.2 minimum for normal text (SC 1.4.3)	Text and anything that must be read on the wild page
explore	Under 4.5:1	Mood, large decorative areas, concept work. Never body text

Each pair also reports whether it reaches 3:1, the minimum for UI parts such as icons, borders and focus rings (SC 1.4.11). A pair can be explore for text and still fine for an icon.

A wild palette is explore by default in spirit: it serves one page, not your product. Swatches on the board get ship when their color is part of at least one passing pair.

A sample reply

The shape of the tool’s answer, shortened, with example values:

Palette of 6 colors:
- #f4f1ea oklch(95.6% 0.011 84.6) (surface)
- #1d2a5c oklch(29.5% 0.084 270.2) (on-surface)
- #2f5bd3 oklch(52.1% 0.18 264.1) (primary)
...
5 of 18 contrast pairs pass 4.5:1 for text (ship); the rest are explore only.
- #1d2a5c on #f4f1ea: 12.4:1
Added 6 swatches to the canvas.

The skill turns it into two tables (palette with roles, then contrast with a Text and a UI column) and suggests which way to move OKLCH lightness to rescue the best explore colors. Those suggestions need a re-check.

Where the palette goes next

• Hand-off files say only ship colors carry text. See Hand off.
• Tokens and Tailwind theme (Pro, gobanana-asset-kit): override tokens for the page, plus up to 4 safe gradients built only from ship pairs, so text stays readable across the whole gradient.
• DESIGN.md front matter takes ship colors only; explore colors stay in prose as “concept only”.

When images are skipped

extract_palette lists each skipped item with a reason:

Reason	What to do
not an image item on this canvas	Pass image item ids from get_canvas
its image host is not on the allowlist	Pick a reference from another source
its format (for example WebP) is not supported yet	Pick another item
the image is too large / took too long to load	Pick another item, or retry

If no image could be read, there is no palette, and the message says why for each item.