banana-logo

name	banana-logo
description	Generate logo concepts and brand identity marks — abstract marks, lettermarks, mascot emblems, and geometric icons with minimal clean aesthetics. Triggers on: logo, brand mark, wordmark, lettermark, icon logo, brand identity, monogram, emblem, logo design, logo concept.
allowed-tools	Bash(uv:*), Bash(ls:*), Read

Logo & Brand Identity

Input: $ARGUMENTS (optional — brand name, industry, and style direction)

If $ARGUMENTS is provided, use it as the brand brief and skip to prompt building. If empty, ask about the brand.

Requirements

• uv installed
• GEMINI_API_KEY environment variable set (get one at https://aistudio.google.com/apikey)

Workflow

1. Understand — Clarify the brand name, industry, personality adjectives (e.g., bold, playful, minimal), and any existing color palette or symbol preferences the user has.
2. Build prompt — Compose a generation prompt following the Prompt Formula below, incorporating the user's brand attributes.
3. Configure — Apply the Defaults (1:1, 1K, Pro model). Override only if the user explicitly requests a different setting.
4. Generate — Run the script.
5. Deliver — Report the saved file path. Do NOT read the image file back. Remind the user of the Text Caveat if letterforms are included. Offer to iterate.

Prompt Formula

[Brand Symbol/Shape] + [Static Balanced Pose] + [White Background] + [Centered Symmetric Composition] + [Minimal Flat Vector / Geometric]

Defaults

ALWAYS apply these unless the user explicitly overrides:

Setting	Value
Aspect ratio	1:1
Resolution	1K
Model	Pro

Key Constraints

• Favicon test -- The logo must work at 16x16 px favicon size. Avoid fine details, thin strokes, and intricate ornamentation.
• Color limit -- Maximum 2-3 colors. Fewer colors reproduce better across media.
• White background -- Always include "on a white background" in the prompt for easy extraction and compositing.
• Shape language -- Angular shapes convey tech / aggressive energy. Rounded shapes convey friendly / approachable energy. Choose deliberately.
• TEXT CAVEAT -- Gemini is unreliable for exact letterforms. Warn the user: treat any text in the generated image as a visual concept only and recreate it in a proper vector tool (Figma, Illustrator, Inkscape) for final use.

Logo Type Guidance

Type	When to use	Prompt emphasis
Abstract mark	Brand wants a unique symbol not tied to a literal object	Geometric shapes, overlapping forms, negative space
Lettermark	Brand name is long or acronym-friendly	Bold single letter or monogram, simple sans-serif geometry
Mascot	Brand targets a playful or community-driven audience	Simplified character, minimal detail, bold outline
Geometric icon	App icon or tech product needing a clean scalable mark	Primitive shapes (circle, square, triangle), flat color fills

Generation

uv run "${CLAUDE_PLUGIN_ROOT}/scripts/banana.py" \
  --prompt "<detailed prompt following the formula>" \
  --output "<YYYY-MM-DD-HH-MM-SS-descriptive-name>.png" \
  --resolution 1K \
  --aspect-ratio 1:1 \
  --model gemini-3-pro-image-preview

Editing (with input images)

When the user provides an existing logo or sketch to refine:

uv run "${CLAUDE_PLUGIN_ROOT}/scripts/banana.py" \
  --prompt "<edit instruction: what to change AND what to keep>" \
  --output "<YYYY-MM-DD-HH-MM-SS-descriptive-name>.png" \
  --input-image "/path/to/source.png" \
  --resolution 1K \
  --aspect-ratio 1:1

For logo refinements, be explicit about what to preserve:

"Simplify this sketch into a clean geometric vector mark using only two colors: deep navy and white. Keep the overall shape and proportions exactly the same."

Up to 14 input images can be passed (repeat --input-image for each).

References

See references/prompts.md for ready-to-use example prompts.