dsh-client-ui-font-scale

A DeepSeek Harness client (browser) plugin that puts conversation font-size controls where you are already looking: a stepper in the composer tool row, keyboard shortcuts, and Ctrl+wheel zoom.

No build step. The lib/*.js files are authored directly in the shipped bundle format, so cloning the repository is enough.

Why this exists

DSH already ships a conversation font-size setting — Settings → General → 字号大小 / Font size, contributed by @deepseek-ai/dsh-client-ui-theme. Its copy is explicit that it "only affects conversation content", which is exactly the right scope.

This plugin does not replace or reimplement it. It adds the input surfaces that setting lacks:

reaching it takes four clicks, so it is easy to forget it exists;
there is no keyboard shortcut for it anywhere in the shipped shortcuts registry;
there is no wheel gesture for it.

Every control here writes through the same theme.setFontSize entry point the shipped row uses, so the two can never disagree.

What it does

Surface	Where	Behaviour
Stepper	composer tool row, before the submit action	`A−` / readout / `A+`, clamping at the ends
Reset	beside the stepper	`↺` restores the default; greys out when already there
Shortcuts	`Ctrl`+`=` / `Ctrl`+`-` / `Ctrl`+`0`	increase / decrease / restore default
Zoom	`Ctrl`+wheel over the page	wheel up enlarges, wheel down shrinks

Both the readout and the reset button render the live size from the theme snapshot, so a change made in the shipped settings row updates this control immediately, and vice versa.

Requirements

DeepSeek Harness with the Web client (the desktop profile, or any profile mounting @deepseek-ai/dsh-web-app).
A theme service that exposes setFontSize — i.e. @deepseek-ai/dsh-client-ui-theme, which ships in the default composition.
No build step and no runtime dependencies beyond the browser module table.

Install

This package is a dsh bundle: package.json declares dsh.bundle.patch, so dsh treats cordis.patch.yml as a composition layer and mounts it for you.

dsh plugin --profile 
 add dsh-client-ui-font-scale

That installs the package into the profile and appends it to the profile's bundle list. The profile is watched, so dsh recomposes without a restart. Remove it with dsh plugin --profile remove dsh-client-ui-font-scale.

From a local checkout

dsh plugin --profile desktop add /absolute/path/to/dsh-client-ui-font-scale

Mounting by hand

Compose cordis.patch.yml into the profile's own patch file, and make the package resolvable from the profile directory:

pnpm add link:/absolute/path/to/dsh-client-ui-font-scale --dir "$DSH_HOME/profiles/desktop"

# $DSH_HOME/profiles/
/cordis.patch.yml
- insert:
    - id: font-scale
      name: dsh-client-ui-font-scale

A patch insert row may also name a path instead of a package — dsh rewrites ./-relative and absolute names to file URLs anchored at the patch file — which needs no install at all.

After installing, reload the page: a client plugin's bundle is wired into the index at render time, so a page that was already open does not pick up a newly installed bundle.

Persistence

This plugin stores nothing, deliberately.

theme.setFontSize(px) writes through the ui-theme settings scope on the Host (this.host.set('fontSize', px)), and @deepseek-ai/dsh-client-ui-theme's Host half re-embeds that durable value into every index render as a boot script. The result:

the size survives a page reload;
the size survives an application restart;
it is applied before the shell mounts, so there is no flash of the default size.

A second store here would be a second source of truth for one number. If you want to change how the size persists, change it in dsh-client-ui-theme, not here.

Range

The accepted range is 10–22 px in whole steps, default 14. That range belongs to the theme service: setFontSize throws for a fractional or out-of-range value. Every control here clamps rather than bypassing it, so the shipped settings row and this plugin always agree.

If you need to go beyond 22 px, note that dsh-client-ui-layout writes the size as an unimportant inline --dsh-content-font-size on ``, so a stylesheet rule with !important can override it. Doing that from a plugin means owning the resulting split-brain with the shipped setting, which is why this plugin does not.

How it works

Concern	Mechanism
Seat	`ctx.slots.register` into `conversation.input.right` (a list slot, `replaceRisk: none`, empty in the default composition)
Read	`theme.getTheme().fontSize`, re-rendered on the `theme/change` event
Write	`theme.setFontSize(px)` — the only font-size write entry
Keys	`ctx.shortcuts.register`, so bindings appear on the Shortcuts settings page and stay user-rebindable
Locale	`ctx.locale.register` + `ctx.locale.bind`; the readout and labels follow the active locale
Styles	one `` element inserted in `ctx.effect`, removed on dispose

Two ordering details are load-bearing:

Services are resolved per call (ctx.get('theme')), not captured once in apply. A peer half may mount after this one, and a captured miss would silently disable a surface for the whole run.
Shortcuts and dictionaries register through ctx.inject, which waits for the service instead of racing it. Registering against a not-yet-mounted service is a no-op, not an error, so the failure would be silent.

Shortcut bindings declare regions: ['page', 'editable'], so they keep working while the composer has focus. On the desktop runtime no combination is reserved (bindingIssue returns early for desktop on Windows and macOS), so Ctrl+= / - / 0 register cleanly.

Development

node scripts/validate-plugin.mjs .
# or
npm run validate

The validator is read-only and asserts the contract this bundle depends on: the dsh.client manifest, the dsh.bundle.patch layer, apply() on the host half, the __ModuleLoader__.load wrapper with a factory id equal to the package name, require('react') beside createElement, CSS template-literal integrity, and locale-dictionary symmetry. It reads dictionary keys out of the object literals themselves, so labels reached through a variable still count.

Also worth running before a commit:

node --check lib/client.js && node --check lib/index.js

Repository layout

lib/index.js                host half (empty apply: the bundle owns no host capability)
lib/client.js               browser half: slots, shortcuts, wheel, styles
cordis.patch.yml            the bundle's composition layer
scripts/validate-plugin.mjs structural validation

Caveats

The control is a decoration in the composer row, not a settings replacement. The shipped Settings → General → Font size row remains the canonical place to see and set the value.
Ctrl+wheel calls preventDefault, which suppresses the Electron shell's own page zoom. That is intentional — the gesture should mean one thing — but it does mean Ctrl+wheel no longer zooms the whole page.
The wheel handler is attached to window, so the gesture works anywhere over the page, not only over the conversation column.

dsh-client-ui-font-scale

Install

README