The Release Asset Engine

What you’re building

Every release means the same grind: take your cover art, open Photoshop or Canva, resize it for Spotify Canvas (9:16), Instagram Reels (9:16), YouTube Shorts (9:16), YouTube Community (1200x900), SoundCloud banner (2480x520) — five-plus crops of the same image, every single time.

You’re going to build a tool that does all of that in one command.

Point your AI CLI tool at a single piece of cover art and watch it generate a folder of platform-ready assets — properly sized, centered, with clean padding that preserves your minimalist aesthetic. No stretching, no cropping your artwork awkwardly. Just clean, platform-ready files.

The platform specs

Here’s what you’re targeting:

Your cover art is probably square (3000x3000 for Spotify/Apple Music). The tool needs to place that square image onto backgrounds of different aspect ratios without distortion.

The prompt

Open your terminal, navigate to a project folder, start your AI CLI tool, and paste this prompt:

Build a Node.js CLI tool called resize-assets.js that takes a single square cover
art image and generates properly sized versions for every major music platform.

REQUIREMENTS:

1. INPUT
   - Accept a file path to a square image (JPG or PNG) as the first argument
   - Accept an optional --output or -o flag for output directory (default: ./release-assets)
   - Accept an optional --bg flag for background color (default: extract dominant
     color from the image, or fall back to #0a0a0a)

2. OUTPUT FILES (generate all of these)
   - spotify-canvas.jpg (720x1280, 9:16 vertical)
   - instagram-reel.jpg (1080x1920, 9:16 vertical)
   - youtube-shorts.jpg (1080x1920, 9:16 vertical)
   - youtube-community.jpg (1200x900, 4:3 landscape)
   - soundcloud-banner.jpg (2480x520, ultra-wide)
   - og-image.jpg (1200x630, social sharing)

3. RESIZING STRATEGY
   - For vertical formats (9:16): center the square artwork in the middle of the
     canvas, scale it to fit the width, fill top/bottom with the background color
   - For landscape formats: center the artwork, scale it to fit the height, fill
     left/right with the background color
   - For the SoundCloud banner: the artwork is very small relative to the canvas,
     so center it and keep generous padding on both sides
   - NEVER stretch or distort the image. NEVER crop the artwork.
   - Use sharp (npm package) for image processing

4. OUTPUT
   - Create the output directory if it doesn't exist
   - Print each file as it's generated with dimensions
   - Print total file count and output directory path when done

5. STYLE
   - Clean, minimal output. No emoji. File paths and dimensions only.
   - Add a --preview flag that generates an HTML file (preview.html) showing all
     assets in a grid so I can visually verify them in a browser

What you get

After your AI CLI tool finishes (typically 60-90 seconds), you’ll have a few files:

resize-assets.js
package.json

your AI CLI tool will likely install the sharp dependency automatically. If not, run npm install in the same folder.

Try it

Grab any square image — your latest cover art, or even a placeholder. Run it:

node resize-assets.js your-cover-art.jpg --preview

You should see output like:

Created release-assets/spotify-canvas.jpg (720x1280)
Created release-assets/instagram-reel.jpg (1080x1920)
Created release-assets/youtube-shorts.jpg (1080x1920)
Created release-assets/youtube-community.jpg (1200x900)
Created release-assets/soundcloud-banner.jpg (2480x520)
Created release-assets/og-image.jpg (1200x630)
Created release-assets/preview.html

6 assets generated in ./release-assets

Open preview.html in your browser. You should see all six assets displayed in a grid. Check each one:

• Is the artwork centered?
• Is there clean padding (not white — your background color)?
• Is the artwork NOT stretched or cropped?

If something is off

LLMs occasionally produce code with small bugs. Here are the most common issues and one-line fix prompts:

Customize it

The base tool works, but here are follow-up prompts to make it fit your workflow better:

Add your logo watermark

Add a --watermark flag that accepts a small PNG logo file. When provided, place the
logo in the bottom-right corner of each asset at 5% of the canvas width, with 60%
opacity. This is for my "moodmixformat" wordmark on promo assets.

Add Spotify Canvas video

Add a --canvas-video flag. When set, instead of a static image for spotify-canvas,
generate an 8-second looping MP4 where the cover art slowly zooms in from 100% to
105% scale with a subtle parallax drift. Use ffmpeg (assume it's installed). Spotify
Canvas requires 720x1280, 3-8 seconds, H.264, under 8MB.

Batch process an album

Add support for passing a directory of images instead of a single file. When a
directory is given, process each image in it and create a subfolder per image in the
output directory, named after the input filename. This is for processing an entire
album's worth of singles art at once.

How it works (the 2-minute explanation)

You don’t need to understand every line, but here’s the mental model:

1. sharp is a Node.js image processing library (like Photoshop in code). It reads your image, lets you resize and composite it onto a canvas.
2. For each platform, the tool creates a blank canvas at the target dimensions, fills it with your background color, then places your artwork centered on that canvas.
3. The key math: for vertical formats (9:16), the artwork fits the width, so the height has padding. For landscape formats, the artwork fits the height, so the width has padding.
4. The preview HTML is a simple page that displays all generated images in <img> tags so you can visually verify everything.

Try it yourself

1. Open your AI CLI tool in an empty folder.
2. Paste the main prompt.
3. Run the tool with any square image.
4. Open the preview HTML and verify all six assets.
5. Pick one customization from the list above and add it.

If you want to go further, try feeding it the cover art from your next release. The first time you watch six platform-ready assets appear in seconds instead of spending 20 minutes in Canva, you’ll never go back.

Key takeaways

• One prompt, one tool: a detailed prompt produces a working image resizer in under 2 minutes.
• CLI tools automate repetitive creative work — resizing the same image for 6 platforms is busywork, not creative work.
• Never stretch, never crop — the strategy of placing artwork on a colored canvas preserves your aesthetic across every aspect ratio.
• Iterative customization is the pattern: get a working base, then add watermarks, video, or batch processing one prompt at a time.
• sharp is the standard for Node.js image processing — knowing it exists means you can always extend this tool.

What’s next

In the next lesson, you’ll build a 7-Day Release Campaign Generator — feed it metadata about a new track and get platform-specific captions, hashtag packs, a posting calendar, and a deployable EPK webpage. Same pattern: one prompt, one tool, then customize.