feat(git): show which checkout the branch picker targets

The BranchSelector popover gets a context row ("Branch in <folder>" in
local mode, "Base branch for <folder>" in worktree mode, full path on
hover) and the trigger tooltip gains the checkout path, so switching a
branch with multiple checkouts of the same repo is unambiguous. Uses
the existing cross-platform getFileName helper, and switches the
sidebar worktree chip's name derivation to it as well (fixes full-path
chip labels on Windows).

Generated-By: PostHog Code
Task-Id: 783b5974-b3ee-4b5e-9ff6-fbc93a6794c5

Author: webjunkie

packages/ui/src/features/git-interaction/components/BranchSelector.test.tsx

@@ -165,3 +165,57 @@ describe("BranchSelector cloud mode", () => {
     expect(onCloudBranchCommit).toHaveBeenCalledTimes(1);
   });
 });
+
+describe("BranchSelector checkout context", () => {
+  it.each([
+    {
+      name: "local mode shows which checkout the branch switch applies to",
+      workspaceMode: "local" as const,
+      expectedPrefix: "Branch in",
+    },
+    {
+      name: "worktree mode labels the pick as the base branch for the checkout",
+      workspaceMode: "worktree" as const,
+      expectedPrefix: "Base branch for",
+    },
+  ])("$name", async ({ workspaceMode, expectedPrefix }) => {
+    const user = userEvent.setup();
+    renderInTheme(
+      <BranchSelector
+        repoPath="/repos/code-wt"
+        currentBranch="main"
+        workspaceMode={workspaceMode}
+        onBranchSelect={vi.fn()}
+      />,
+    );
+
+    await user.click(screen.getByRole("combobox", { name: "Branch" }));
+
+    const contextRow = await screen.findByText(expectedPrefix, {
+      exact: false,
+    });
+    expect(contextRow).toHaveTextContent(`${expectedPrefix} code-wt`);
+    expect(contextRow).toHaveAttribute("title", "/repos/code-wt");
+  });
+
+  it("shows no checkout row in cloud mode (the repo picker sits next to it)", async () => {
+    const user = userEvent.setup();
+    renderInTheme(
+      <BranchSelector
+        repoPath="owner/repo"
+        currentBranch={null}
+        workspaceMode="cloud"
+        cloudBranches={["main"]}
+        cloudBranchesLoading={false}
+        cloudSearchQuery=""
+        onBranchSelect={vi.fn()}
+        onCloudSearchChange={vi.fn()}
+      />,
+    );
+
+    await user.click(screen.getByRole("combobox", { name: "Branch" }));
+
+    expect(screen.queryByText("Branch in", { exact: false })).toBeNull();
+    expect(screen.queryByText("Base branch for", { exact: false })).toBeNull();
+  });
+});

packages/ui/src/features/git-interaction/components/BranchSelector.tsx

@@ -21,6 +21,7 @@ import {
   InputGroupAddon,
   InputGroupButton,
 } from "@posthog/quill";
+import { getFileName } from "@posthog/shared";
 import type {
   GitBusyOperation,
   GitBusyState,
@@ -196,6 +197,11 @@ export function BranchSelector({
       ? busyOperationLabel
       : (displayedBranch ?? "No branch");
 
+  // Which checkout the branch applies to. With several checkouts of the same
+  // repo registered (main clone + worktrees), a bare branch name is ambiguous
+  // — in local mode picking one runs a real checkout in this directory.
+  const checkoutName = !isCloudMode && repoPath ? getFileName(repoPath) : null;
+
   const showSpinner =
     effectiveLoading || (isCloudMode && open && cloudBranchesFetchingMore);
 
@@ -295,7 +301,17 @@ export function BranchSelector({
       filter={isCloudMode ? null : undefined}
     >
       <Tooltip
-        content={disabledReason ?? displayedBranch ?? "Switch branch"}
+        content={
+          disabledReason ??
+          (checkoutName && repoPath ? (
+            <span className="flex flex-col">
+              <span>{displayedBranch ?? "Switch branch"}</span>
+              <span className="text-gray-10">in {repoPath}</span>
+            </span>
+          ) : (
+            (displayedBranch ?? "Switch branch")
+          ))
+        }
         side="bottom"
         open={hovered && !open && !effectiveLoading}
       >
@@ -405,6 +421,16 @@ export function BranchSelector({
           </InputGroupAddon>
         </ComboboxInput>
 
+        {checkoutName ? (
+          <div
+            className="truncate border-border border-b px-2 py-1.5 text-muted-foreground text-xs"
+            title={repoPath ?? undefined}
+          >
+            {isSelectionOnly ? "Base branch for " : "Branch in "}
+            <span className="font-medium">{checkoutName}</span>
+          </div>
+        ) : null}
+
         {isCloudMode && cloudBranchesFetchingMore ? (
           <LoadingRow label={`Loading more (${branches.length})…`} />
         ) : null}

packages/ui/src/features/sidebar/components/TaskListView.tsx

@@ -12,6 +12,7 @@ import type {
   TaskGroup,
 } from "@posthog/core/sidebar/sidebarData.types";
 import { MenuLabel } from "@posthog/quill";
+import { getFileName } from "@posthog/shared";
 import { builderHog } from "@posthog/ui/assets/hedgehogs";
 import { useFolders } from "@posthog/ui/features/folders/useFolders";
 import { useArchivingTasksStore } from "@posthog/ui/features/sidebar/archivingTasksStore";
@@ -100,18 +101,15 @@ function TaskRow({
   const worktreeCheckout = useMemo(() => {
     if (workspace?.worktreePath) {
       return {
-        name:
-          workspace.worktreeName ??
-          workspace.worktreePath.split("/").pop() ??
-          workspace.worktreePath,
+        name: workspace.worktreeName ?? getFileName(workspace.worktreePath),
         path: workspace.worktreePath,
       };
     }
     if (workspace?.mode === "local" && workspace.folderPath) {
       const folder = folders.find((f) => f.path === workspace.folderPath);
       if (folder?.mainRepoPath) {
         return {
-          name: workspace.folderPath.split("/").pop() ?? workspace.folderPath,
+          name: getFileName(workspace.folderPath),
           path: workspace.folderPath,
         };
       }