dsh-plugin-infinite-split-tabs

Infinite split tabs for the DeepSeek Harness right sidebar: split down as well as right,
nest panes in both directions, drag tabs to any edge, and keep every layout across reloads.

> Status: source patch, not yet a drop-in dsh plugin add package.
> DSH links ui-dockkit into the Web shell statically, and ui-sidebar-right owns the dock.
> A third-party plugin cannot replace that split renderer at runtime, so this repository
> ships the working patch plus the test/build evidence. See ROADMAP.md for the
> plugin conversion.

Proposal

Posted in upstream GitHub Discussions (Ideas):

Split the right sidebar in both directions (nested panes)

Review

The source diff is recorded as a draft PR in the contributor's fork:

jeremytenjo/deepseek-harness#1 — feat(sidebar): split down and unbounded nested panes

deepseek-ai/deepseek-harness currently disables external pull requests, so the PR cannot be
opened against the upstream repository. The fork PR is the reviewable record of the same
24-file change shipped in this repository's patches/ directory.

Features

• Split down — ⌘⇧\ on macOS, Ctrl+Shift+\ on Windows/Linux.
• Split right — the existing ⌘\ still works.
• Nest both ways — split any pane again, along either axis; there is no two-pane cap.
• Drag to any edge — left, right, top or bottom; the drop hint names the target.
• Persistent layouts — the nested split tree is saved per Session and restored.
• Stable tab bodies — tabs stay siblings in one flat CSS Grid, so terminals and file
  previews are not remounted by nesting.
• One-line borders — every pane on the panel's left edge draws its border, and stacked
  panes share a single 1px seam (no doubled divider line).

Install (from source)

The patch is built against deepseek-ai/deepseek-harness at commit 22ddee3
(the 0.2.1-rc.3 tree). Use a matching checkout; newer master may conflict.

git clone https://github.com/deepseek-ai/deepseek-harness.git
cd deepseek-harness
git checkout 22ddee3

git apply /path/to/dsh-plugin-infinite-split-tabs/patches/0001-right-sidebar-infinite-splits.patch

pnpm install
pnpm run dev:web

Open the printed URL, open a Session and the right sidebar, then click a tab and press
⌘⇧\ / Ctrl+Shift+\.

For a desktop build:

pnpm run build
pnpm run package:desktop:dir

Apply helper

./scripts/apply.sh /path/to/deepseek-harness

The script runs git apply --check first and refuses a dirty/conflicting tree.

Test

pnpm exec vitest run packages/client/ui-dockkit/tests packages/client/ui-sidebar-right/tests
pnpm exec tsc -p packages/client/ui-sidebar-right/tsconfig.json --noEmit
pnpm exec tsc -b packages/client/ui-dockkit/tsconfig.json

At the recorded revision: 542 tests pass, both packages typecheck, and a live headless
Chrome run built a five-pane nested tree, restored it after reload, and dragged a nested
divider.

Screenshots

How it works

The patch touches three layers:

1. ui-dockkit — TabLayout flattens the split tree into one CSS Grid; each pane maps to
   the Grid tracks its rectangle covers, and each split gets a divider overlay sized to its
   own rectangle. planSplitPane/DockController take an axis. The docked-pane ceiling is
   removed (MAX_DOCK_PANES = Infinity).
2. ui-sidebar-right — the store/service accept nested splits and top/bottom drops; the
   pane.splitDown shortcut is registered; persistence validates arbitrary trees.
3. Borders — left-edge and seam classes replace the old first-column/column-only rules.

Compatibility and caveats

• Built and tested against DSH 0.2.1-rc.3.
• The split strip button still splits right; downward split is the shortcut/API.
• Edge drops use the dock kit's 25% edge bands (all four edges).
• There is no pane cap, so very deep trees can get cramped; the room rule still refuses a
  split when a pane cannot hold two working halves.
• Stock DSH rejects these nested layouts; downgrading clears that Session's stored layout.
• Upstream currently disables external pull requests; this repo is the distribution path.

License

MIT. Portions are derived from DeepSeek Harness (MIT); see
THIRD_PARTY_NOTICES.md.