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Split Panel (called Split Right in menus and shortcuts) divides the Alter Hub into two independent conversation panes. Keep research, source material, or an agent task trace in one pane while you write, compare, or iterate in the other — without copying text by hand.
Split Panel is a Hub-only feature. QuickHub stays a single floating panel; open a chat in the Hub (⌘⇧H or Open in Hub) to use split layout.

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What Split Panel does

When split is active, the Hub shows:
  1. Left pane (primary) — your original conversation tabs
  2. Right pane (secondary) — a second set of tabs, focused independently
Each pane has its own tab bar, prompt box, context strip, and model selection. Drag the divider between panes to resize. Split layout persists when you quit and reopen Alter.

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When to use Split Panel

Split Panel shines when one conversation feeds another:
  • Research → draft — keep source notes or a long transcript in the left pane; write the output in a fresh chat on the right
  • Compare approaches — run two model threads on the same problem and cross-reference answers
  • Read while you chat — preview a PDF or markdown file in the right pane while asking questions in the left
  • Follow agent work — open a task or computer_use_task trace in the other pane to watch progress without losing your main thread
Split Panel is built around Alter’s context system. The main payoff is moving conversations, files, snippets, and attachments between panes as context — not just seeing two chats at once.

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Open and close split

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Split Right

1

Tab bar button

In the Hub, click the Split Right icon (split-columns button) next to the + tab button on the left pane
2

Keyboard shortcut

Press ⌘⌥N (default) — configurable in Settings → Shortcuts → Hub & QuickHub → Split Right
3

Window menu

Choose Window → Split Right
4

Command Palette

Press ⌘K, type split, and choose Split Right
Split Right opens a new chat in the right pane and moves keyboard focus there. The new tab inherits the model from your current left-pane tab. If split is already open, Split Right focuses the right pane instead of creating another split.

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Close Split

1

Secondary tab bar

Click the × on the right pane’s tab bar
2

Keyboard shortcut

Press ⌃⌘↓ (default) — Close Split in Settings → Shortcuts → Hub & QuickHub
3

Window menu or Command Palette

Choose Close Split from the Window menu or ⌘K command palette
Closing split merges all right-pane tabs into the left pane. Your conversations are preserved; only the layout closes.
You can also drag tabs between panes or use the tab context menu:
  • Open in Split — opens split (if needed) and moves the tab to the other pane
  • Move to Other Pane — moves the tab when split is already active
Configure all split shortcuts under Settings → Shortcuts → Hub & QuickHub.

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Bridge context between panes

Context bridging is Split Panel’s core workflow. Context copied or added to the other pane becomes an independent copy in the destination tab’s context strip — ready to @-mention, inspect, or send with your next prompt.

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Add a whole conversation as context

Turn an entire conversation in one pane into context for the chat in the other pane:
1

From a tab

Right-click a conversation tab → Open as Context in Split (opens split automatically) or Add as Context to Other Pane (when split is already open)
2

From the sidebar

With split open, focus the pane that should receive context. Right-click a conversation in the sidebar → Add as Context
3

From the @ menu

Type @ in the prompt box. When split is active, an Other Pane section lists the conversation open in the opposite pane. Select it to attach a snapshot.
The snapshot includes the full conversation formatted as markdown. You cannot attach the same conversation to itself twice.

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Drag context cards

When split is open:
  1. Select one or more context cards in the conversation (files, snippets, app context, etc.)
  2. Drag them to the other pane’s prompt area or context strip
  3. Alter copies them into the destination tab
Works for files, text selections, images, calendar events, app snapshots, and most other context types.
Workspace context cannot be transferred between panes. Attach workspace-backed files individually, or open the workspace in the destination tab separately.

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Right-click inside a conversation

From messages in either pane: Modifier-click shortcuts:
  • ⌥-click a document attachment — preview in the other pane (tooltip: Click to open · ⌥-click to preview in split)
  • ⌥-click a task or computer_use_task card — open the task trace in the other pane
If split is not open, Open as Context in Split and Open in Other Pane actions open split for you first.

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Drop files on the other pane

You can also drag files from Finder onto the other pane’s conversation area. They are added to that tab’s context strip like a normal Hub drop.

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Typical workflows

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Research on the left, write on the right

1

Start in the Hub

Open the Hub (⌘⇧H) with your research conversation on the left
2

Split

Press ⌘⌥N to open a fresh chat on the right
3

Bridge context

Right-click the left tab → Add as Context to Other Pane, or type @ and pick the Other Pane conversation
4

Draft

Prompt the right pane: “Using the attached research, draft a one-page summary with three recommendations.”

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Preview a document while chatting

1

Ask in one pane

Run a conversation that produces or references a document attachment
2

Open in split

⌥-click the document card, or right-click → Open in Other Pane
3

Keep asking

The document opens as a read-only preview tab in the other pane while you continue prompting in the first

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Watch an agent task without losing your place

1

Start a task

Ask Alter to run a multi-step task or Computer Use job in your main pane
2

Open trace in split

⌥-click the task tool-call card, or right-click → Open in Other Pane
3

Monitor

Follow the read-only task conversation in the right pane while you queue follow-ups or start a related chat on the left

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Limitations and tips

  • Read-only tabs (document previews, task traces) cannot receive context drops — use a normal conversation tab in that pane as the destination
  • Copied context is independent — edits, follow mode, and removals in one pane do not sync back to the source
  • Model per pane — while split, each pane remembers its own model choice
  • Inspector — available while split (⌃⌘I); opens as a trailing panel alongside the split panes
  • QuickHub — split actions from QuickHub open or focus the Hub window automatically when needed

Window Types

Hub layout, tabs, and the context section

Understand Context

What context is and how Alter uses it

Add Context

Files, apps, and @ mentions

Keyboard Shortcuts

Full shortcut reference including split commands