refactor(desktop): extract db helpers from workspaces router

apps/desktop/src/lib/trpc/index.ts

@@ -45,5 +45,6 @@ const sentryMiddleware = t.middleware(async ({ next, path, type }) => {
 });
 
 export const router = t.router;
+export const mergeRouters = t.mergeRouters;
 export const publicProcedure = t.procedure.use(sentryMiddleware);
 export const trpc = createTRPCReact<AppRouter>();

apps/desktop/src/lib/trpc/routers/workspaces/procedures/branch.ts

@@ -0,0 +1,105 @@
+import { projects, workspaces } from "@superset/local-db";
+import { eq } from "drizzle-orm";
+import { localDb } from "main/lib/local-db";
+import { terminalManager } from "main/lib/terminal";
+import { z } from "zod";
+import { publicProcedure, router } from "../../..";
+import {
+	getBranchWorkspace,
+	getWorkspace,
+	setLastActiveWorkspace,
+	touchWorkspace,
+} from "../utils/db-helpers";
+import { listBranches, safeCheckoutBranch } from "../utils/git";
+
+export const createBranchProcedures = () => {
+	return router({
+		getBranches: publicProcedure
+			.input(
+				z.object({
+					projectId: z.string(),
+					fetch: z.boolean().optional(), // Whether to fetch remote refs (default: false, avoids UI stalls)
+				}),
+			)
+			.query(async ({ input }) => {
+				const project = localDb
+					.select()
+					.from(projects)
+					.where(eq(projects.id, input.projectId))
+					.get();
+				if (!project) {
+					throw new Error(`Project ${input.projectId} not found`);
+				}
+
+				const branches = await listBranches(project.mainRepoPath, {
+					fetch: input.fetch,
+				});
+
+				// Get branches that are in use by worktrees, with their workspace IDs
+				const projectWorkspaces = localDb
+					.select()
+					.from(workspaces)
+					.where(eq(workspaces.projectId, input.projectId))
+					.all();
+				const worktreeBranchMap: Record<string, string> = {};
+				for (const ws of projectWorkspaces) {
+					if (ws.type === "worktree" && ws.branch) {
+						worktreeBranchMap[ws.branch] = ws.id;
+					}
+				}
+
+				return {
+					...branches,
+					inUse: Object.keys(worktreeBranchMap),
+					inUseWorkspaces: worktreeBranchMap, // branch -> workspaceId
+				};
+			}),
+
+		// Switch an existing branch workspace to a different branch
+		switchBranchWorkspace: publicProcedure
+			.input(
+				z.object({
+					projectId: z.string(),
+					branch: z.string(),
+				}),
+			)
+			.mutation(async ({ input }) => {
+				const project = localDb
+					.select()
+					.from(projects)
+					.where(eq(projects.id, input.projectId))
+					.get();
+				if (!project) {
+					throw new Error(`Project ${input.projectId} not found`);
+				}
+
+				const workspace = getBranchWorkspace(input.projectId);
+				if (!workspace) {
+					throw new Error("No branch workspace found for this project");
+				}
+
+				// Checkout the new branch with safety checks (terminals continue running on the new branch)
+				await safeCheckoutBranch(project.mainRepoPath, input.branch);
+
+				// Send newline to terminals so their prompts refresh with new branch
+				terminalManager.refreshPromptsForWorkspace(workspace.id);
+
+				// Update the workspace - name is always the branch for branch workspaces
+				touchWorkspace(workspace.id, {
+					branch: input.branch,
+					name: input.branch,
+				});
+				setLastActiveWorkspace(workspace.id);
+
+				const updatedWorkspace = getWorkspace(workspace.id);
+				if (!updatedWorkspace) {
+					throw new Error(`Workspace ${workspace.id} not found after update`);
+				}
+
+				return {
+					workspace: updatedWorkspace,
+					worktreePath: project.mainRepoPath,
+				};
+			}),
+	});
+};