file-compression
# File Compression
Compress files with Python-first workflows and Node.js fallback workflows.
## Supported File Types
- PDF: `.pdf`
- Image: `.jpg`, `.jpeg`, `.png`, `.webp`
## What This Skill Can Do
- Compress PDF with preset quality levels.
- Compress image with quality/resize/format controls.
- Switch backend automatically when dependencies are missing.
- Detect bad compression results and retry with better strategy.
## Installation Spec (Before Running)
Required binaries:
- `python3` (recommended `>= 3.8`)
- `node`
- `gs` (Ghostscript, required for PDF Ghostscript paths)
Python install spec:
```bash
python3 -m pip install -r {baseDir}/requirements.txt
```
Node install spec:
```bash
cd {baseDir}
npm install
```
Ghostscript install examples:
- macOS: `brew install ghostscript`
- Ubuntu/Debian: `sudo apt-get update && sudo apt-get install -y ghostscript`
Safety note:
- Explain to the user before each install command that third-party packages are being installed.
- If installation fails, report the failing command and switch to available fallback backend.
## CLI Options Cheat Sheet
PDF (`scripts/compress_pdf.py`):
- `--preset screen|ebook|printer|prepress`
- `--strategy auto|ghostscript|pikepdf`
- `--remove-metadata`
- `--no-linearize`
- `--overwrite`
PDF Node (`scripts/compress_pdf_node.mjs`):
- `--preset screen|ebook|printer|prepress`
Image (`scripts/compress_image.py`):
- `--quality <1-100>`
- `--format keep|jpeg|png|webp`
- `--max-width <n>`
- `--max-height <n>`
- `--strategy auto|pillow|node`
- `--overwrite`
Image Node (`scripts/compress_image_node.mjs`):
- `--quality <1-100>`
- `--format keep|jpeg|png|webp`
- `--max-width <n>`
- `--max-height <n>`
## Example Set (Python + Node)
PDF default:
```bash
python {baseDir}/scripts/compress_pdf.py in.pdf out.pdf
```
PDF aggressive:
```bash
python {baseDir}/scripts/compress_pdf.py in.pdf out.pdf --preset screen --strategy ghostscript
```
PDF with pikepdf:
```bash
python {baseDir}/scripts/compress_pdf.py in.pdf out.pdf --strategy pikepdf --remove-metadata
```
PDF via Node:
```bash
node {baseDir}/scripts/compress_pdf_node.mjs in.pdf out.pdf --preset ebook
```
Image default:
```bash
python {baseDir}/scripts/compress_image.py in.jpg out.jpg --quality 75
```
Image convert + resize:
```bash
python {baseDir}/scripts/compress_image.py in.png out.webp --format webp --quality 72 --max-width 1920
```
Image force Node backend:
```bash
python {baseDir}/scripts/compress_image.py in.jpg out.jpg --strategy node --quality 70
```
Image direct Node:
```bash
node {baseDir}/scripts/compress_image_node.mjs in.jpg out.jpg --quality 70 --max-width 1600
```
## Environment and Fallback
Check and install in this order:
1. Python: `python3 --version` (fallback: `python --version`)
2. Node: `node --version`
3. Ghostscript: `gs --version` (required for PDF Ghostscript paths)
4. Python deps when needed:
- `pip install pikepdf`
- `pip install pillow`
5. Node deps when needed:
- `npm install`
Fallback policy:
- PDF: `ghostscript` -> `pikepdf` -> `node-ghostscript`
- Image: `pillow` -> `node-sharp`
If `python3.8+` is unavailable, try `python3.11/3.10/3.9/3.8`; if still blocked, use Node flow when possible.
## Execution Transparency
Always communicate each step:
1. Tell user what you are checking or running.
2. Show the exact command before execution.
3. For slow steps (`pip install`, `npm install`, large Ghostscript jobs), say you are waiting.
4. After each step, report result and next action.
## Bad Result Recovery
When `output_size >= input_size`, do not stop:
1. Report exact from/to numbers and compression ratio.
2. Explain likely cause:
- PDF: already optimized, scanned-image content, metadata overhead, unsuitable preset.
- Image: unsuitable format conversion, quality too high, small-file overhead.
3. Retry with alternate strategy:
- PDF: `ebook -> screen`, then switch backend.
- Image: lower quality, switch backend, convert to `webp`, optionally resize.
4. Return the best attempt and state which command produced it.
## Agent Response Contract
After every compression task, always return:
1. Output absolute path.
2. `from <before_size> to <after_size>`.
3. `saved <delta_size> (<ratio>%)`.
4. Backend used.
标签
skill
ai
