fix(vcs): prefill the New Branch dialog with the current branch name (#1073)

A plain New Branch (single and multi-repository) now opens with the current branch name, like JetBrains IDEs, so a related branch is an edit away; detached HEAD stays empty. New Branch from a local ref now applies its <ref>-copy suggestion, which was computed but never used.

Co-authored-by: a-rookie-of-C-language <[email protected]>

src/features/vcs/__tests__/branchOps.test.ts

@@ -0,0 +1,46 @@
+import { beforeEach, expect, it, vi } from "vitest";
+import type { BranchInfo } from "@/bindings";
+const mocks = vi.hoisted(() => ({ prompt: vi.fn() }));
+vi.mock("../dialogs", async (original) => ({
+  ...(await original<typeof import("../dialogs")>()),
+  promptText: mocks.prompt,
+}));
+import { newBranch, newBranchInRepos } from "../branchOps";
+import { useVcs } from "../store";
+
+const branch = (head: string | null): BranchInfo => ({
+  head,
+  headCommit: "abc1234567890",
+  upstream: null,
+  ahead: 0,
+  behind: 0,
+  operation: null,
+});
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  useVcs.setState({ root: "/p", repo: "/p/front", branch: branch("feature/ui") });
+  // Cancel: only what the dialog was offered matters here, not its outcome.
+  mocks.prompt.mockResolvedValue(null);
+});
+
+it("prefills a plain New Branch with the current branch name", async () => {
+  await newBranch();
+  expect(mocks.prompt.mock.calls[0]?.[0].initial).toBe("feature/ui");
+});
+
+it("prefills nothing when HEAD is detached", async () => {
+  useVcs.setState({ branch: branch(null) });
+  await newBranch();
+  expect(mocks.prompt.mock.calls[0]?.[0].initial).toBe("");
+});
+
+it("still suggests a remote branch's name without the prefix", async () => {
+  await newBranch("origin/main");
+  expect(mocks.prompt.mock.calls[0]?.[0].initial).toBe("main");
+});
+
+it("prefills the current branch in the multi-repository dialog too", async () => {
+  await newBranchInRepos(["/p/front", "/p/back"]);
+  expect(mocks.prompt.mock.calls[0]?.[0].initial).toBe("feature/ui");
+});

src/features/vcs/branchOps.ts

@@ -145,11 +145,18 @@ export async function checkoutBranch(name: string) {
 /** New Branch: creates a branch from HEAD (or `from`) and, by default, checks it out. */
 export async function newBranch(from?: string) {
   const repo = currentRepo();
-  const suggestion = from ? (from.includes("/") ? shortRemoteName(from) : `${from}-copy`) : "";
+  // IDEA opens the dialog with a suggestion instead of an empty field: a
+  // remote's name without the prefix, the source ref as `-copy`, or the
+  // current branch for a plain New Branch from HEAD.
+  const suggestion = from
+    ? from.includes("/")
+      ? shortRemoteName(from)
+      : `${from}-copy`
+    : (useVcs.getState().branch?.head ?? "");
   const r = await promptText({
     title: from ? tx`Create New Branch from ${from}` : "Create New Branch",
     label: "New branch name:",
-    initial: from && from.includes("/") && !validateBranchName(suggestion) ? suggestion : "",
+    initial: suggestion && !validateBranchName(suggestion) ? suggestion : "",
     mono: true,
     okLabel: "Create",
     validate: validateBranchName,
@@ -360,7 +367,7 @@ export async function newBranchInRepos(roots: readonly string[], from?: string)
   const r = await promptText({
     title: from ? tx`Create New Branch from ${from}` : "Create New Branch",
     label: tx`New branch name (in ${roots.length} repositories):`,
-    initial: from?.includes("/") ? shortRemoteName(from) : "",
+    initial: from ? (from.includes("/") ? shortRemoteName(from) : "") : (useVcs.getState().branch?.head ?? ""),
     mono: true,
     okLabel: "Create",
     validate: validateBranchName,