dsh-plugin-webui-bg

A DeepSeek Harness (DSH) WebUI plugin: pick a local image as the WebUI background, overlaid with a translucent mask that matches the current theme (light / dark), so the image never disturbs the UI's readability.

Features

• A Background image row in Settings → General:
  • Pick a local image (browser file picker), or use the built-in Sample image to try it instantly
  • Images are downscaled (max edge 1920px) and re-encoded (WebP, JPEG fallback) before persistence
  • Live preview thumbnail
  • Enable / disable toggle
  • Mask opacity slider (50%–100%, default 75%)
  • Background blur slider (0–40px, default 0)
  • One-click Remove background
• The mask color uses the theme token --dsw-alias-bg-base, so it follows the light/dark theme automatically.
• Both background layers are pointer-events: none fixed layers — they never block interaction.
• Privacy: the image never leaves your browser. It is stored in localStorage (key dsh.webui-bg); no network requests are made.

How it works

The DSH layout frame and its full-viewport children (body, sidebar column, conversation root, …) carry their own opaque backgrounds that would otherwise paint over the background layers. The plugin:

1. Appends two fixed layers to document.body: the image behind, the theme-colored mask in front (both pointer-events: none).
2. Neutralizes every large fully-opaque "surface" container it finds under the layout frame (size heuristics, no hashed-class dependence), so the layers show through. Cards, buttons and bubbles keep their own backgrounds for readability.
3. Skips overlay-like subtrees (modals, popovers, tooltips — anything fixed/absolute or with a positive z-index), so dialogs stay opaque.
4. Watches the DOM with a MutationObserver and re-neutralizes on remounts; restores the original backgrounds when the background is disabled.

Persistence is browser-local on purpose: DSH's API gateway only exposes allowlisted settings namespaces to configuration clients, so a third-party namespace would be refused on the wire.