workspace: Add ActivateLastPane action

[gh-xj]

Summary

Add workspace::ActivateLastPane so users can bind a shortcut (for example cmd-9) to focus the last pane.

Why

Today, the closest option is workspace::ActivatePane with an index (for example 8), but that has side effects: when the index does not exist, it creates/splits panes (activate_pane_at_index fallback).

ActivateLastPane gives a stable, no-surprises target: focus the rightmost/last pane in current pane order, never create a new pane.

Context

This capability has been requested by users before:

• Support activate last pane #17503 (comment)

Prior art

VS Code exposes explicit editor-group focus commands and index-based focus patterns (e.g. workbench.action.focusSecondEditorGroup ... focusEighthEditorGroup) in its workbench commands:

• https://github.com/microsoft/vscode/blob/main/src/vs/workbench/browser/parts/editor/editorCommands.ts#L675-L724

Zed already follows numbered pane focus in default keymaps (ActivatePane 1..9 on macOS/Linux/Windows), so adding a dedicated "last pane" action is a small, natural extension:

• assets/keymaps/default-macos.json
• assets/keymaps/default-linux.json
• assets/keymaps/default-windows.json

Change

• Added workspace::ActivateLastPane
• Implemented Workspace::activate_last_pane(...)
• Wired action handler in workspace listeners
• Added test_activate_last_pane

Validation

• cargo test -p workspace test_activate_last_pane -- --nocapture
• cargo test -p workspace test_pane_navigation -- --nocapture
• cargo fmt --all -- --check

Risk

Low: focus-only behavior, no layout/data changes, no default keymap changes.

Release Notes:

• Added workspace::ActivateLastPane action for keybindings that focus the last pane.

[Copilot]

Pull request overview

Adds a new workspace-level action to focus the last pane, enabling users to bind a shortcut (e.g. cmd-9) similar to existing “last item” navigation.

Changes:

• Added workspace::ActivateLastPane to the workspace action set.
• Implemented Workspace::activate_last_pane(...) and wired it into workspace action listeners.
• Added test_activate_last_pane to validate focusing behavior across multiple panes.

---

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[Copilot]

ActivateNextPane is registered twice in this listener chain (once around line 6381 and again around line 6409). Div::on_action accumulates listeners, so dispatching ActivateNextPane will run both handlers and advance focus twice (skipping a pane). Remove one of these registrations.

Suggested change

	.on_action(cx.listener(|workspace, _: &ActivateNextPane, window, cx| {
	workspace.activate_next_pane(window, cx)
	}))

[Copilot]

activate_last_pane currently calls self.center.panes() which allocates a Vec just to get the final pane. Since PaneGroup already exposes last_pane(), prefer using that to avoid allocation and to match the semantic intent more directly.

Suggested change

	if let Some(last_pane) = self.center.panes().last().cloned() {
	if let Some(last_pane) = self.center.last_pane() {

[zed-industries-bot]

	Messages
📖	This PR includes links to the following GitHub Issues: #- 17503 If this PR aims to close an issue, please include a Closes #ISSUE line at the top of the PR body.

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[smitbarmase]

Thanks. It's a nice addition.