| name | sg-generate-images |
| effort | low |
| description | Generate slide visuals using Gemini Pro from validated graphics descriptions. Use when you want to generate slide images, create visuals after validation, or see what the slides will look like. |
| argument-hint | <presentation.md> [--resolution high|medium|small] |
| allowed-tools | Bash, Read, Glob, Grep |
Slide Generator: Generate Images Step
Generate slide visuals using Gemini Pro from the validated graphics descriptions in the presentation. Uses a unified prompt builder and async batch generation for efficiency.
Pre-loaded Context
Working directory:
!pwd
Available presentation files:
!ls -la *.md 2>/dev/null | grep -i pres || echo "No presentation files found"
Existing images:
!ls -la images/ 2>/dev/null || echo "No images directory yet"
Prerequisites
- Preflight:
sg --version must succeed before proceeding — if sg is missing, stop and tell the user this requires the private davistroy/slide-generator engine (owner-only; see ADR-0008)
slide-generator package installedGOOGLE_API_KEY set in environment (Gemini Pro access)- A
presentation.md file with validated graphics descriptions
- Graphics validation should be run first (
.graphics_validated marker)
Input Validation
Required:
<presentation.md> - Path to presentation markdown file
Optional:
--resolution <level> - Image resolution: small, medium, high (default: high)--image-format <fmt> - Output format: png, jpg (default: png)--skip-existing - Don't regenerate images that already exist
Instructions
- Verify prerequisites: Confirm
GOOGLE_API_KEY is set and presentation has validated graphics
- Run image generation:
sg generate-images presentation.md --resolution high
- Monitor progress: Image generation takes time (~5-10s per image)
- Verify output: Check that images were created in the
images/ directory
- Report results: Show count of images generated, any failures
How It Works
The image generation step uses:
- Gemini Pro (
gemini-3-pro-image-preview): Google's image generation model
- Unified prompt builder:
prompt_builder.py constructs optimized prompts from descriptions
- Async batch generation: Multiple images generated concurrently via
asyncio
- API key in header: Authentication via header (not query param)
- Block reason diagnostics: Clear error messages when generation is blocked
Error Handling
| Error | Cause | Fix |
|---|
GOOGLE_API_KEY not found | Missing env var | Set the key |
Image blocked | Content policy violation | Review and soften the description |
Rate limit | Too many concurrent requests | Built-in rate limiter handles this |
Generation timeout | Gemini service slow | Retry; increase SG_API_TIMEOUT |
Cost Estimate
- ~$0.10 per image at high resolution
- Typical 20-slide deck: ~$2.00
Output
The step produces:
- PNG/JPG images in an
images/ directory (one per slide)
- File names correspond to slide numbers (
slide-01.png, slide-02.png, etc.)
Next Step
After images are generated, build the final PowerPoint:
sg build presentation.md --template generic
Or use /sg-build to continue the pipeline.
Related Gemini Image Path
This step delegates image generation to the external sg CLI (the slide-generator package), which is unbundled and maintained outside this repo. personal-plugin's visual-explainer skill/tool is a separate, in-tree, tested Gemini image path with its own prompt builder and model config — the two are intentionally independent implementations, not a shared library. Future Gemini model or API changes (e.g. a new model ID, auth scheme, or block-reason handling) must be applied in both places: here (via the external sg package) and in plugins/personal-plugin/tools/visual-explainer/.
