Paperbanana Slide Deck

PaperBanana Slide Deck

End-to-end slide deck creation and modification. Supports two modes: creating new decks from scratch, and regenerating existing decks after prompt edits.

Pipeline: Content → Style Selection → Outline → Prompts → Image Generation → PPTX Merge

Mode Detection

On invocation, determine the mode by checking the target directory:

| Condition | Mode | Start Phase | |-----------|------|-------------| | Target dir missing OR no outline.md | New | Phase R (full RDIV) | | Target dir has outline.md + prompts/ | Modify | Phase I (generate + merge) |

In Modify mode, the user has already edited prompts or outline externally. Skip directly to Phase I.

Dependencies

| Component | Role | Location | |-----------|------|----------| | google-genai SDK | Path B image generation | pip install google-genai | | PaperBanana CLI | Path A image generation | python -m paperbanana.cli slide-batch | | merge-to-pptx.ts | PPTX merge | skills/paperbanana-slide-deck/scripts/merge-to-pptx.ts (local) | | Style libraries | Style presets (4 sources, 150+) | See R1 for discovery paths | | Bun | Run merge script | bun |

Phase R: Research (New Mode Only)

Skip this phase entirely in Modify mode.

R1: Discover style libraries — Scan all four sources and merge into a unified list.

# Source 0 (PRIMARY): Local extended library (123 styles from Fooocus/ComfyUI, structured)
LOCAL_STYLES="$(find ~/.claude/skills .claude/skills -maxdepth 1 -name 'paperbanana-slide-deck' -type d 2>/dev/null | head -1)/references/styles"

# Source 1: baoyu-slide-deck styles (16 slide-optimized)
BAOYU_SLIDE=$(ls -td ~/.claude/plugins/cache/baoyu-skills/content-skills/*/skills/baoyu-slide-deck/references/styles 2>/dev/null | head -1)

# Source 2: baoyu-infographic styles (20 visual-rich)
BAOYU_INFOG=$(ls -td ~/.claude/plugins/cache/baoyu-skills/content-skills/*/skills/baoyu-infographic/references/styles 2>/dev/null | head -1)

# Source 3: theme-factory themes (10 color/typography presets)
THEME_FACTORY=$(ls -td ~/.claude/plugins/cache/anthropic-agent-skills/document-skills/*/skills/theme-factory/themes 2>/dev/null | head -1)

Merge: Glob all four directories for *.md, deduplicate by filename (priority: baoyu-slide-deck > local > baoyu-infographic > theme-factory). Present the full unified list to user during R3.

If none found: Use PaperBanana's 23 built-in presets.

R2: Analyze content — Topic, audience, tone, recommended slide count.

R3: Style recommendation — Recommend 2-3 styles based on content signals. See references/style-guide.md for the full style-to-content mapping table.

R4: Interactive selection — Use AskUserQuestion for style, audience, and slide count.

R5: Save analysis — Create slide-deck/{topic-slug}/analysis.md.

Phase D: Design (New Mode Only)

In Modify mode, the user handles prompt edits directly.

D1: Load style spec — Read from baoyu styles or PaperBanana built-ins.

D2: Generate outline — Create outline.md with slide structure. See references/outline-format.md.

D3: Optional outline review — Ask user if they want to review before proceeding.

D4: Generate prompts — For each slide, create prompts/NN-slide-{slug}.md. Each prompt file has the style instructions block, then ---, then the slide-specific content and design requirements.

Phase I: Implement (Both Modes)

Step I1: Image Generation (Dual Path)

Path A — PaperBanana CLI (preferred, has critic quality review):

cd 
python -m paperbanana.cli slide-batch \
  --prompts-dir "slide-deck/{topic-slug}/prompts" \
  --output-dir "slide-deck/{topic-slug}" \
  --resolution 4k \
  --iterations 2

Auto-degrade trigger: Switch to Path B if any slide (not just the first) hits one of these. Don't keep retrying Path A:

• RetryError / ResourceExhausted / HTTP 429 (rate-limited)
• ServerError (5xx) or non-429 ClientError (4xx)
• Critic takes longer than 3 minutes on any single slide
• User reports "一直 429" / persistent rate limits → degrade immediately, skip further Path A retries

Distinguish two 429 sources:

| Source | Symptom | Response | |--------|---------|----------| | Critic 429 (VLM rate limit) | Error inside critic loop, Path A specific | Auto-degrade to Path B (no critic → bypasses the issue) | | Image-gen 429 (gemini-3-pro-image-preview) | Same error in Path B | Exponential backoff: time.sleep(30 * 2**retry) up to 5 min, then surface to user |

Partial-batch recovery: If some slides were already generated before 429 hit, preserve existing PNGs and resume from the next missing slide (cross-reference prompts/*.md with existing NN-slide-*.png).

> Note (upstream sync pending): Upstream paperbanana CLI (≥ #129) has native batch_checkpoint.json for Path A slide-batch — resume is automatic there. The skip logic above is for the Path B fallback code, which doesn't yet use the upstream checkpoint format.

Path B — Direct Gemini API (fallback, no critic, stable):

from google import genai
from google.genai import types
from PIL import Image
from io import BytesIO
import base64, os, time

# Read API key from paperbanana/.env
client = genai.Client(api_key=GOOGLE_API_KEY)

config = types.GenerateContentConfig(
    response_modalities=['IMAGE'],
    image_config=types.ImageConfig(
        aspect_ratio='16:9',
        image_size='4K',
    ),
)

MAX_RETRIES = 5   # after which surface to user
BASE_SLEEP = 30   # seconds

for prompt_file in sorted(os.listdir(prompts_dir)):
    name = prompt_file.replace('.md', '')
    out_path = os.path.join(output_dir, f'{name}.png')

    # Partial-batch resume: skip slides already generated
    if os.path.exists(out_path):
        continue

    with open(os.path.join(prompts_dir, prompt_file), 'r', encoding='utf-8') as f:
        prompt_text = f.read()

    # Exponential backoff on 429 / transient errors
    for retry in range(MAX_RETRIES):
        try:
            response = client.models.generate_content(
                model='gemini-3-pro-image-preview',
                contents=prompt_text,
                config=config,
            )
            break
        except Exception as e:
            msg = str(e).lower()
            if '429' in msg or 'resource' in msg or 'rate' in msg:
                wait = min(BASE_SLEEP * (2 ** retry), 300)  # cap at 5 min
                time.sleep(wait)
                continue
            raise  # non-429 error → surface immediately
    else:
        raise RuntimeError(f'{name}: 429 after {MAX_RETRIES} retries, surface to user')

    for part in response.candidates[0].content.parts:
        inline = getattr(part, 'inline_data', None)
        if inline and getattr(inline, 'data', None):
            data = inline.data
            img_bytes = base64.b64decode(data) if isinstance(data, str) else data
            img = Image.open(BytesIO(img_bytes))
            img.save(out_path, 'PNG')
            break

    time.sleep(BASE_SLEEP)  # baseline cooldown between slides

The API key is in /paperbanana/.env as GOOGLE_API_KEY. Read it with dotenv or manually.

Step I2: Smart Cleanup (Pre-Merge)

Run AFTER I1 generation, not before. I1 is partial-batch-aware and skips already-generated slides; Cleanup's job is only to remove PNGs whose prompt was deleted/renamed since the last run. Running Cleanup before I1 would delete valid WIP slides from a resumed batch.

Sequencing: I1 (generate + resume) → I2 (cleanup orphans) → I3 (merge).

1. Scan prompts/*.md → build expected PNG set (e.g. 01-slide-hook.md → 01-slide-hook.png)
2. Scan target directory for *.png files matching pattern NN-slide-*.png
3. Delete slide PNGs NOT in expected set (orphans from renamed/deleted prompts)
4. Preserve non-slide PNGs (e.g. logo.png, background.png) and all expected-set PNGs

Step I3: Merge to PPTX

# Locate skill directory dynamically (works on any platform)
SKILL_DIR="$(find ~/.claude/skills .claude/skills -maxdepth 1 -name 'paperbanana-slide-deck' -type d 2>/dev/null | head -1)"
bun "${SKILL_DIR}/scripts/merge-to-pptx.ts" "slide-deck/{topic-slug}"

If merge script unavailable: inform user that PNG images are ready but PPTX merge requires bun and the local merge-to-pptx.ts script.

Phase V: Verify (Both Modes)

V1: Display results — Read and display each generated slide image. Report total slides, output directory, PPTX file path.

V2: User feedback — Ask:

• "Looks great, done!"
• "Regenerate — I'll tell you what to fix in the prompts"

V3: Regeneration — If user wants changes:

1. User edits the specific prompt files
2. Regenerate ALL slides (not just changed ones — ensures visual consistency)
3. Smart cleanup + re-merge PPTX
4. Return to V1

Fallback Behavior

| Situation | Fallback | |-----------|----------| | All style libraries missing | Use PaperBanana built-in presets | | Local merge script missing | Output PNG only, skip PPTX | | Bun/npx missing | Skip PPTX merge, inform user | | Critic 429 / RetryError | Auto-degrade to Path B (no critic) | | Image-gen 429 in Path B | Exponential backoff up to 5 min, then surface | | Partial batch already generated | Resume from next missing slide, preserve existing PNGs |

Output Structure

slide-deck/{topic-slug}/
  analysis.md            ← R phase (New mode only)
  outline.md             ← D phase
  prompts/               ← D phase
    01-slide-hook.md
    02-slide-cover.md
    ...
  01-slide-hook.png      ← I phase
  02-slide-cover.png
  ...
  {topic-slug}.pptx      ← I phase

Quick Reference

# Path A: PaperBanana CLI batch
python -m paperbanana.cli slide-batch --prompts-dir prompts/ --resolution 4k --iterations 2

# Path A: single slide (supports --vlm-model)
python -m paperbanana.cli slide --input prompt.md --resolution 4k

# List available styles
python -m paperbanana.cli slide --list-styles

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: PlutoLei
• Source: PlutoLei/paperbanana-skill
• License: MIT
• Homepage: https://github.com/llmsresearch/paperbanana

Install and usage instructions live in the source repository linked above.