dsh-middle-click-tab-close

Middle-click a tab in DeepSeek Harness's right sidebar to close it — the gesture browsers give their own tabs, for the tabs dsh opens for files, the terminal, deliverables and the guide.

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The gesture

Right sidebar
┌──────────────────────────────────────────────────────────┐
│  Report ×   Guide   Terminal ×   +   ⬒   ⤢   ⌄          │
│        ↑                                                 │
│   middle-click here closes the tab, exactly like ×       │
└──────────────────────────────────────────────────────────┘

A left click selects a tab. A right click opens its menu. A middle click now closes it — on the docked strip and on a floating pane's title alike.

Why this is a plugin and not a setting

The strip is shipped UI, and it has no seat for a per-tab gesture:

Owner	What it does
dsh-client-ui-dockkit	draws each chip as role="tab" with data-dockkit-tab="<tab id>"; its chip handler is onPointerDown: e => { if (e.button !== 2) onTabPressed(...) } — it skips exactly one button, right-click, so a middle press selects the tab and stops there
dsh-client-ui-sidebar-right	owns the column, the tab registry and the documented navigation controller ctx.sidebarRight.close(tabId)

No user setting turns the gesture on, and no slot exposes the chip. The only way to add it without forking or patching the shipped strip is to observe the chip in the page and call the same close path the UI already uses.

What it contributes

Surface	What it does
one capturing pointerdown listener on document	resolves the pressed chip and closes its tab
the host half (exports["."])	inert: it exists only so the Loader row can carry the browser half
Config, styles, slots, routes	none

No panel, no settings card, no HTTP surface.

How a press is handled

Step	What happens
1	button === 1 and the press is inside [data-sidebar-right-session]
2	the pressed element's closest [data-dockkit-tab] supplies the layout tab id
3	a chip that draws no [data-dockkit-tab-close] is left alone — the sole docked guide is protected by the shipped UI
4	ctx.sidebarRight.close(tabId) runs the shipped close path: resource cleanup handlers, the last-tab-collapses-the-column rule and layout undo history all behave exactly as they do for the chip's ×
5	preventDefault() suppresses Chromium's middle-click autoscroll, and stopPropagation() keeps dockkit from ever seeing the press
6	the gesture's listener lives in ctx.effect, so disabling the plugin or unloading it removes it

Because step 4 is the documented controller rather than a synthetic click on the ×, a tab type's registerCloseHandler still runs, and closing the only tab in a pane still collapses the column in one history entry.

Why capturing on document works

React 18 delegates onPointerDown at the root container, which sits below document in the capture path. A capturing listener on document therefore runs first; stopPropagation() prevents the event from reaching the container, so the kit's chip handler never runs and no drag begins.

test/react-delegation.spec.tsx renders the chip through React with a live onPointerDown and asserts both halves of that: a middle press never reaches the handler, and a left press still does.

Protected and floating tabs

• The sole docked guide stays open. It draws no close control and sidebarRight.close() ignores it; the plugin refuses the press instead of swallowing it for no effect.
• Floating panes have no tab chip. Their title is data-dockkit-float-title with a close button beside it, so a middle press there clicks that button — the kit's own close path — and the pane closes as if the button were used.

What it does not do

• It does not close tabs with any other button, gesture or shortcut.
• It does not touch background Sessions: only the foreground column's visible chips are reachable, which is the only place a pointer can land.
• It keys off dockkit's DOM markers (data-dockkit-tab, data-dockkit-tab-close, data-sidebar-right-session) — the same markers ui-sidebar-right itself uses to resolve a tab from the DOM. If a future dsh renames them, the gesture stops working (harmlessly) rather than misfiring.
• It cannot make the gesture native: a middle press still reaches the browser first, so the tab closes on pointerdown, not on auxclick.

Install

Build and pack from this repository:

pnpm install
pnpm check                       # typecheck · build · vitest
pnpm pack                        # -> dist/dsh-middle-click-tab-close-0.1.0.tgz

Then, in the DeepSeek Harness desktop app, open Settings → Plugins, install dist/dsh-middle-click-tab-close-0.1.0.tgz, and restart the app. A bundle added to a running profile is not in the module resolution computed at boot, so its entry fails to import until the next start. The web client also needs a page reload after that restart.

Development

pnpm install
pnpm check          # typecheck the host half, the browser half and the tests; build; vitest

To see the package composed and served without touching the app's profile:

scripts/dev-profile.sh boot 19498     # isolated DSH home under .dev-home/
scripts/dev-profile.sh url 19498      # prints the served bundle URL
scripts/dev-profile.sh remove

The gesture's own browser check is by hand: open the right sidebar, middle-click a tab, and confirm the tab closes and its close handler ran.

Verification

Level	Result
Typecheck: host half, browser half, tests	clean
Built lib/client.js behind a fake window.__ModuleLoader__	registers under the package name, exports apply + inject: ['sidebarRight']
Behaviour in jsdom against the built bundle	closed chip, title and close-control presses, protected guide, outside the sidebar, other buttons, floating pane, listener disposal
React 18 delegation order	middle press never reaches the chip's onPointerDown; left press still does
Composition in an isolated dsh profile	the Loader row composed, the boot graph carried the entry with its inject, and the bundle was served
Live middle click in the desktop GUI	not automated — the one check left to a human

Files

src/
├── index.ts              # host half: the Loader row's inert entry point
└── client/index.ts       # the document listener, chip resolution, close call
test/
├── loader.ts             # the built bundle behind a fake module loader
├── bundle.spec.ts        # loader id + exports
├── middle-click.spec.ts  # the gesture in jsdom
└── react-delegation.spec.tsx  # capture-before-React proof
scripts/
├── dev-profile.sh        # isolated dsh home for composition checks
└── install.sh            # pack, then print the install path

Contributing

Issues and pull requests are welcome — the bug form asks which step of the press broke, which is usually enough to reproduce. CONTRIBUTING.md has the commands and the map of what each spec pins. Report vulnerabilities through SECURITY.md rather than a public issue. This project follows the Contributor Covenant.

If this saves you a trip to the × on every tab, a ⭐ star helps other DSH users find it.

License

MIT — see LICENSE.