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 <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 <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/<profile>/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 <body>, 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 <style> 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.
License
MIT © 2026 AprilCrystal
