/nano-banana

name: nano-banana
description: "Generate professional presentation slides and high-quality illustrations using Gemini image generation API (Nano Banana 2), with interactive browser-based review and iterative editing. Full workflow: content planning conversation → slides_plan.json → batch image generation → review with feedback → targeted slide editing → PPTX packaging. Use when: user wants to create a presentation, make slides, generate a PPT/PPTX, prepare a talk deck, design visual slide content, or generate high-quality figures/illustrations for papers and documents. Do NOT use for: writing academic papers (use paper-writing) or planning academic conference talk narrative structure (use academic-slides)."
allowed-tools: "write_file edit_file read_file think_tool execute"
metadata:
  author: EvoScientist
  version: '1.0.0'
  tags: [core, presentation, image-generation]

Nano Banana

Generate high-quality presentation slides as images using Gemini's image generation API, review them interactively in a browser, and iteratively edit based on feedback.

When to Use This Skill

• User asks to create a presentation, slide deck, or PPT
• User wants to generate visual slides for a talk or lecture
• User has a document or outline and wants slides based on it
• User says "make me a PPT", "generate slides", "create a presentation"
• User wants to edit or refine existing generated slides
• User needs high-quality figures, diagrams, or illustrations for papers or documents
• User asks to generate research figures, architecture diagrams, or concept illustrations

**Do NOT use for:**

• Writing academic papers → use `paper-writing`
• Planning academic conference talk narrative structure → use `academic-slides`

---

Before You Start: Prerequisites

Before proceeding with any slide generation, verify these prerequisites. Script and style paths in this document are relative to this skill's directory.

1. **Dependencies**: `pip install pillow google-genai python-pptx python-dotenv` (also listed in `requirements.txt` at the skill root). Install into the environment the user is working in.

2. **API Key**: Check that a Google API key is available. Run:

   echo $GOOGLE_API_KEY

If empty, ask the user to provide one. They can either:

• Set it via config: `EvoSci config set google_api_key <key>`
• Provide it directly (pass via `--api-key` argument)
• If the user provides the key in conversation, pass it to scripts with `--api-key`

3. **Language**: Ask the user what language the slide content should be in. This affects the content you write in `slides_plan.json`, not the style template.

---

Core Workflow

Phase 1: Content Planning Conversation     ← most important phase
Phase 2: Generate slides_plan.json
Phase 3: Select Style & Generate Slides
Phase 4: Launch Review Server
Phase 5: Apply Feedback Edits              ← repeat Phase 4-5 until satisfied
Phase 6: Package as PPTX
Phase 7: Cleanup

Follow these phases in order. Do NOT skip Phase 1 — the quality of generated slides depends directly on planning depth.

---

Phase 1: Content Planning Conversation

This is the most critical phase. Rushing to generation without proper planning produces mediocre slides. Engage the user in a structured conversation:

**Step 1 — Understand the context:**

• What is the topic of the presentation?
• Who is the audience? (technical peers, executives, students, general public)
• How long is the talk? (this determines page count)
• What is the occasion? (conference, internal talk, lecture, pitch)

**Step 2 — Define the storyline:**

• What is the opening hook? (a surprising fact, a question, a trend)
• What are the 3-5 main sections or arguments?
• What is the key takeaway the audience should remember?
• What is the closing message?

**Step 3 — Outline per-page content:**

• For each slide, agree on: title + 2-4 key points + visual description
• Identify which slides are cover, content, or data type
• Ensure logical flow between pages

**Duration-to-page-count guidance:**

| Duration | Pages | Structure | |----------|-------|-----------| | 5 min | 5 | Cover + 3 content + closing | | 10-15 min | 8-12 | Cover + intro + 3-4 sections + summary + closing | | 20-30 min | 15-20 | Cover + intro + 5-6 sections + summary + closing | | 45-60 min | 25-30 | Cover + intro + 7-9 sections (2-3 pages each) + summary + closing |

**If the user provides a document or outline**, read it thoroughly, then propose a slide breakdown for approval before proceeding.

---

Phase 2: Generate slides_plan.json

Create a `slides_plan.json` file in the workspace root with this schema:

{
  "title": "Presentation Title",
  "total_slides": 10,
  "slides": [
    {
      "slide_number": 1,
      "page_type": "cover",
      "content": "Title: My Presentation\nSubtitle: A subtitle here\nLabel: 2026 Edition"
    },
    {
      "slide_number": 2,
      "page_type": "content",
      "content": "Title: First Topic\nKey points:\n- Point one\n- Point two\n- Point three"
    },
    {
      "slide_number": 3,
      "page_type": "data",
      "content": "Title: Key Metrics\nMetric 1: 95% accuracy\nMetric 2: 3x faster\nMetric 3: 10k users"
    }
  ]
}

**page_type values:** `cover`, `content`, `data`

Critical Content Field Rules

The `content` field is what gets passed to the image generation model. Follow these rules strictly:

1. **DO** write descriptive titles and bullet points 2. **DO** describe the visual layout you want (e.g., "left-right comparison", "4 icon cards") 3. **DO NOT** prefix lines with "Slogan:", "Visual:", "Points:", or any meta-labels — the model will render these as visible text on the slide 4. **DO NOT** put the same sentence in both the title area and the bottom of the content — it causes duplication 5. **DO NOT** include footer text, page numbers, or watermark instructions

**Bad example** (meta-labels leak as visible text):

Title: Why AI Matters
Visual: left-right compar