Nano Banana 2 Promptor

Generate optimized image generation prompts for Nano Banana 2 (Gemini 3.1) from natural conversation context. The skill analyzes what the user wants, applies design intelligence, and outputs a structured JSON prompt ready to paste into Nano Banana 2.

Why This Skill Exists

Nano Banana 2 is a thinking model — it understands creative intent, physics, and composition. It responds dramatically better to narrative descriptions than keyword lists. This skill bridges the gap between what users want ("a cool t-shirt design") and what Nano Banana 2 needs (a richly detailed, design-informed narrative prompt).

Core Pipeline

1. CONTEXT PARSER → detect/infer dimensions from any input format
2. CATEGORY ROUTER → POD path or Commercial path
3. PROMPT COMPOSER → narrative prompt with design intelligence
4. JSON OUTPUT → structured output ready for use

Step 1: Parse Context

Accept ANY input format — free-form text, structured fields, or minimal keywords. Extract these 8 dimensions:

Dimension What to detect Inference when missing

subject The core product/object/concept Required — ask if truly ambiguous

category One of the 10 categories below Infer from subject + purpose

audience Target demographic/psychographic Infer from subject + style

purpose What the image is for (platform/use) Default: "general commercial use"

style_hints Any style/aesthetic direction Infer via context (see Style Inference)

text_content Text to render in the image None unless specified

brand_voice Tone/personality Infer from style + audience

constraints What to avoid or must include None unless specified

10 Supported Categories

Category Triggers on

product_hero

Product shots, studio photography, hero images

lifestyle

Products in real-world settings, contextual scenes

social_media

Instagram, Facebook, Pinterest, TikTok content

pod_tshirt

T-shirt designs, apparel graphics

pod_mug

Mug designs, drinkware, wrap-around

pod_poster

Posters, wall art, fine art prints

pod_accessories

Phone cases, tote bags, stickers

marketing_banner

Web banners, email headers, ad creatives

infographic

Data visuals, comparison charts, bento grids

logo_brand

Logos, brand marks, icons

Style Inference

When the user provides no style direction, infer the optimal style from context:

For POD categories — read references/niche-modules.md and select the closest niche module based on subject + audience. The niche module defines typography, color, composition, and motif rules. If no niche fits cleanly, default to the niche that best matches the audience's identity signal.

For commercial categories — default to clean, professional photography aesthetic with modern composition. Match platform conventions (Instagram = vibrant/scroll-stopping, LinkedIn = professional, Pinterest = aspirational).

Step 2: Route by Category

POD Path (pod_tshirt, pod_mug, pod_poster, pod_accessories)

For POD categories, apply design intelligence from the reference files:

• Read references/niche-modules.md — select the matching niche module and apply its rules for color limits, negative space targets, typography, composition, and motifs

• Read references/design-principles.md — apply core design philosophy principles

• Generate a mini design philosophy (2-3 sentences) — a poetic aesthetic direction inspired by the subject/audience that guides the visual tone. Think of it as naming a tiny art movement. Example: "Neon Nostalgia — vivid retro-futurism meets handcrafted warmth, where each element appears labored over with master-level care."

• Apply the One Idea Principle — the design must communicate exactly ONE thing. If the context implies multiple competing ideas, distill to the strongest single concept.

• Set background rule — Nano Banana 2 cannot generate transparent backgrounds. Instead:

• If design is predominantly dark → use pure solid white background (#FFFFFF)

• If design is light/colorful → use pure solid black background (#000000)

• Always add: "clean isolated background with sharp edges, no gradients, no ambient shadows, no noise — optimized for AI background removal"

Commercial Path (product_hero, lifestyle, social_media, marketing_banner, infographic, logo_brand)

For commercial categories, apply Nano Banana 2 prompting best practices:

• Read references/prompt-patterns.md — select camera specs, lighting setups, and composition patterns for the category

• Set platform-specific aspect ratio:

• Instagram feed: 4:5

• Instagram story / TikTok: 9:16

• Facebook ad: 1:1 or 4:5

• Pinterest: 2:3

• Web banner: 16:9 or 21:9

• Email header: 3:1

• General: 4:3 or 16:9

• For product_hero — add camera hardware language (e.g., "Sony A7III, 85mm f/1.4, studio softbox lighting") as this dramatically improves photorealistic output

• For marketing_banner — reserve negative space for text overlay, describe composition zones explicitly

• For lifestyle — add environmental storytelling, atmospheric lighting, contextual props

Step 3: Compose the Prompt

Assemble a narrative-style prompt (not keyword lists). Nano Banana 2 is a thinking model — it performs dramatically better with descriptive paragraphs that explain creative intent.

Prompt Formula

[STYLE DECLARATION] + [SUBJECT DESCRIPTION] + [SETTING/ENVIRONMENT] + [COMPOSITION & HIERARCHY] + [LIGHTING] + [TYPOGRAPHY if any] + [TECHNICAL SPECS] + [CONSTRAINTS]

Writing Rules

• Narrative over keywords: "Create a dark gothic illustration of a highly detailed skull intertwined with blooming roses" beats "skull, roses, gothic, dark, detailed, illustration"

• Specific over vague: "weathered ceramic coffee mug with visible glaze cracks" beats "old mug"

• Camera language for realism: Include lens focal length, aperture, camera model when photorealistic output is needed

• Film stock as shorthand: "Shot on Kodak Portra 400" triggers warm tones + fine grain

• Text in quotes: Any text to render in the image must be wrapped in quotation marks with font description: "STAY WILD" in bold condensed sans-serif font, ALL-CAPS

• Design hierarchy language: Describe what the viewer sees first, second, third — this maps to the three-level visual hierarchy (primary 40-60%, secondary 25-35%, tertiary 15-25%)

• Craftsmanship emphasis: For POD designs, include language like "meticulously crafted", "painstaking attention to detail", "master-level execution" — this pushes Nano Banana 2 toward higher quality output

• Prompt length: Aim for 100-250 words. Enough detail to guide the model, not so much that it gets confused.

Anti-Pattern Guards

Before finalizing the prompt, verify it does NOT contain:

• Multiple competing focal points with no hierarchy (the "Shouting Match")

• More elements than the niche allows (the "Kitchen Sink")

• Keyword-stuffed quality modifiers like "4k, ultra HD, masterpiece, best quality" (Nano Banana 2 ignores these; use narrative instead)

• Requests for transparent backgrounds (not supported — use solid bg)

• Conflicting style directions ("vintage but also modern and futuristic")

Step 4: Output JSON

Always output in this exact structure:

{ "context_analysis": { "detected": { "subject": "what was explicitly stated", "category": "detected category", "audience": "detected or null", "purpose": "detected or null", "style_hints": "detected or null", "text_content": "detected or null", "brand_voice": "detected or null", "constraints": ["detected constraints"] }, "inferred": { "niche_module": "selected niche or null (POD only)", "color_system": "inferred palette description", "composition_template": "selected composition approach", "negative_space_target": "percentage", "typography_style": "font direction if applicable", "aspect_ratio": "W:H", "resolution": "4K", "background": "solid black/white + reasoning (POD only)" }, "design_philosophy": "2-3 sentence mini art movement (POD only, null for commercial)" }, "prompt_components": { "style": "visual style declaration", "subject": "detailed subject description", "setting": "environment/background description", "composition": "layout, hierarchy, eye flow", "typography": "text rendering instructions or null", "lighting": "lighting setup description", "technical": "aspect ratio, resolution, background", "constraints": "what to avoid" }, "assembled_prompt": "The complete, ready-to-use narrative prompt combining all components into flowing paragraphs. This is what gets pasted directly into Nano Banana 2.", "metadata": { "model_target": "nano_banana_2", "aspect_ratio": "W:H", "resolution": "4K", "category": "the category", "niche_module": "if applicable", "design_rules_applied": ["list of rules that shaped this prompt"] } }

Reference Files

These contain detailed domain knowledge. Read them as needed based on the category:

references/niche-modules.md

Read when: category is any POD type Contains: 10 niche modules (streetwear premium, streetwear hype, anime, rock/metal, hip-hop, skate/surf, vintage/retro, luxury gothic, pop culture, minimalist) with specific rules for typography, color limits, negative space, composition, motifs, and production. Also contains the niche selection decision tree.

references/prompt-patterns.md

Read when: any category (but especially commercial path) Contains: Nano Banana 2 specific prompting formulas, camera/lens specifications by category, lighting setups, platform aspect ratios, text rendering rules, and example prompts for each category.

references/design-principles.md

Read when: category is any POD type Contains: The design philosophy generation system, core mindset rules, visual hierarchy framework, composition systems, anti-patterns with diagnoses, and the One Idea Principle. Distilled from validated streetwear brand analysis.

Important Reminders

• Nano Banana 2 is a THINKING model. Write prompts that explain intent, not just list attributes.

• For POD: always use solid background (black or white) for easy AI removal. Never say "transparent background."

• The assembled_prompt should be a cohesive narrative, not a concatenation of the components.

• Quality comes from specificity and design intelligence, not from quality modifier keywords.

• When in doubt about style, lean toward strategic restraint — "premium design whispers, amateur design shouts."