dsh-plugin-zoom

A DeepSeek Harness plugin that adds a manual interface-zoom preference, so the Web UI can be enlarged or shrunk on high-DPI displays and make its text easier to read.

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Features

Three entry points drive one zoom value (75 %–200 %, 5 % steps):

• Settings → General → Interface zoom: a stepper with zoom-in/zoom-out arrows, the current zoom (e.g. 125 %), the display scale the window is rendered at (e.g. 当前显示器：200%), and a Reset action back to 100 %.
• Ctrl (⌘ on macOS) + mouse wheel anywhere in the window: zooms in 5 % steps and cancels the page's own wheel zoom so only one zoom applies.
• A compact − 125 % + control in the Session header's top-right corner (in the header utilities, after the shipped buttons). Click the percentage to reset to 100 %.

The preference is remembered (host-scoped cookie plus a same-origin localStorage mirror), so it survives reloads and app restarts.

How it works

The Client half sets one CSS property on the document root:

html { zoom: 1.25; }

Chromium scales layout, text, and fixed/overlay surfaces together, so the whole Web UI — dialogs, menus, toasts, and the settings panel itself — follows one ratio, and text is re-rasterized at the larger size rather than stretched. The settings row is registered in the host's own settings.general.item seat, the header control in the Session header's additive conversation.session.header.utilities seat, and both are styled with host theme tokens, matching the surrounding controls in light and dark themes.

Why a plugin and not the OS setting

Windows display scaling changes physical size but not the app's logical density. On a large high-DPI monitor the UI can still be too small (or, for some users, too large) for comfortable reading. The operating-system setting also affects every application. This plugin zooms only the Harness Web UI, by a value you pick, and remembers it.

Fixed in 0.1.2: tooltips and menus drifting once zoomed

A CSS zoom on the document root makes Chromium report getBoundingClientRect() and window.innerWidth/innerHeight in visual (already zoomed) pixels, while position: fixed descendants are zoomed a second time. The host UI positions its tooltips, hover cards and menus from exactly those values, so they drifted away from their anchor by (scale − 1) × distance from the top-left corner — the bug reported against 0.1.1. 0.1.2 installs a geometry-space shim that converts those reads back to the layout pixels CSS uses (and, after a one-time auto-detection, pointer clientX/clientY too), so the host's own positioning, drag and hit-test math behaves exactly as it does at 100 %. The shim is the identity at 100 % and unload restores the prototypes. React DevTools fixed the same browser behavior in facebook/react#37519.

Escape hatch if you need to compare against the uncompensated behavior (browser DevTools console; takes effect after a reload):

localStorage.setItem('dsh-plugin-zoom:no-geometry-shim', '1');
// localStorage.removeItem('dsh-plugin-zoom:no-geometry-shim');

Notes and limits

• The zoom is remembered in the browser through a cookie (host-scoped, so it survives the desktop shell's per-launch loopback port change) with localStorage as a same-origin mirror.
• The zoom is a presentation preference; the Host writes nothing, and the agent receives no state from it.
• Fractional zoom is allowed, but for the crispest text prefer whole percentages: 100 %, 125 %, 150 %, 200 %.
• Electron's native window buttons are not scaled by an in-page CSS zoom (they are drawn by the OS above the page). At scales far from 100 % the custom titlebar can look slightly taller than the native caption buttons. This is a cosmetic limitation of every renderer-side zoom; the plugin deliberately does not touch Electron's native window zoom, which a plugin's Host half (a separate Node-mode process) cannot reach.
• A high zoom makes the shell's logical window narrower; the sidebar may auto-collapse earlier, exactly as it would with browser page zoom.
• Scrolling containers, dialogs, menus, and toasts are all inside the zoomed document, so they follow the same ratio.
• The plugin was previously named dsh-plugin-dpi-scale; a zoom already chosen under that name is migrated automatically the first time this version loads.

Requirements

• A DSH profile that supports bundles (@deepseek-ai/dsh-base / Web profile). Developed and verified against DSH desktop 0.2.1-rc.2.
• Node.js >= 22 is only needed for the repository check script.

Installation

Install from npm through the DSH plugin manager:

plugin_manager action=install_bundle target=dsh-plugin-zoom@0.1.3

Or install from a local checkout (a directory install links the checkout, which is convenient while developing):

plugin_manager action=install_bundle target=D:\path\to\dsh-plugin-zoom

A new bundle is applied through HMR immediately; after changing the plugin's source, reload the page (or restart DSH) to load a fresh client module.

Develop

• client.js — the whole feature: preference state, document zoom, the Ctrl+wheel shortcut, the General row, and the Session-header control (plain classic script registered on window.__ModuleLoader__).
• index.js — the Host half; intentionally empty.
• cordis.patch.yml — inserts the zoom Loader row.
• locale/*.json — Plugin Manager title/description (en, zh).

Run npm run check before committing.

Publishing

.github/workflows/publish.yml publishes through npm trusted publishing (OIDC). Configure this repository (workflow publish.yml, environment npm) as a trusted publisher on npmjs.com, then publish a GitHub release whose tag equals the package.json version (for example v0.1.3). The workflow checks that the tag matches, validates the packed files, and publishes with provenance.

License

MIT. See LICENSE.