test(FN-4623): cover backend layout resolution paths

Fusion-Task-Id: FN-4623
Fusion-Task-Lineage: 58122853-cab7-4102-9649-4ceda4c5959e

packages/engine/src/__tests__/worktree-backend.test.ts

@@ -112,6 +112,13 @@ describe("NativeWorktreeBackend", () => {
       expect.objectContaining({ cwd: "/repo", timeout: 120000, maxBuffer: 10485760 }),
     );
   });
+
+  it("resolves native worktree path via configured worktreesDir", async () => {
+    const backend = new NativeWorktreeBackend({ settings: { worktreesDir: "../{repo}.worktrees" } as any });
+    await expect(
+      backend.resolveWorktreePath({ rootDir: "/repo/project", worktreeName: "fn-1", branch: "fusion/fn-1" }),
+    ).resolves.toBe("/repo/project.worktrees/fn-1");
+  });
 });
 
 describe("WorktrunkWorktreeBackend", () => {
@@ -268,6 +275,29 @@ describe("WorktrunkWorktreeBackend", () => {
     ).rejects.toMatchObject({ code: "worktrunk_sync_conflict", operation: "sync" });
   });
 
+  it("resolves worktrunk path from wt config show template", async () => {
+    execFileMock.mockResolvedValue({ stdout: '{"config":{"worktree-path":"{{ repo_path }}/../{{ repo }}.{{ branch | sanitize }}"}}', stderr: "" });
+    const backend = new WorktrunkWorktreeBackend({ binaryPath: "worktrunk" });
+
+    await expect(
+      backend.resolveWorktreePath({ rootDir: "/repo/project", worktreeName: "ignored", branch: "fusion/fn-1" }),
+    ).resolves.toBe("/repo/project.fusion-fn-1");
+    expect(execFileMock).toHaveBeenCalledWith(
+      "worktrunk",
+      ["config", "show", "--format", "json"],
+      expect.objectContaining({ cwd: "/repo/project", timeout: 5000, maxBuffer: 10485760 }),
+    );
+  });
+
+  it("falls back to default layout template when config cannot be read", async () => {
+    execFileMock.mockRejectedValue(new Error("missing config"));
+    const backend = new WorktrunkWorktreeBackend({ binaryPath: "worktrunk" });
+
+    await expect(
+      backend.resolveWorktreePath({ rootDir: "/repo/project", worktreeName: "ignored", branch: "fusion/fn-1" }),
+    ).resolves.toBe("/repo/project/.worktrees/fusion-fn-1");
+  });
+
   it("prunes by listing worktrees and removing worktrunk managed entries", async () => {
     execMock.mockResolvedValue({
       stdout:

packages/engine/src/__tests__/worktree-paths.test.ts

@@ -4,6 +4,7 @@ import { join, resolve } from "node:path";
 import {
   isInsideConfiguredWorktreesDir,
   resolveTaskWorktreePath,
+  resolveTaskWorktreePathForBackend,
   resolveWorktreesDir,
 } from "../worktree-paths.js";
 
@@ -47,4 +48,17 @@ describe("worktree-paths", () => {
     expect(isInsideConfiguredWorktreesDir(rootDir, undefined, join(rootDir, ".worktrees", "fn-1"))).toBe(true);
     expect(isInsideConfiguredWorktreesDir(rootDir, undefined, join(rootDir, "fn-1"))).toBe(false);
   });
+
+  it("delegates to worktrunk backend path resolver", async () => {
+    const resolver = async () => "/tmp/custom/fusion-fn-1";
+    await expect(
+      resolveTaskWorktreePathForBackend(rootDir, "fn-1", undefined, { kind: "worktrunk", resolveWorktreePath: resolver }, "fusion/fn-1"),
+    ).resolves.toBe("/tmp/custom/fusion-fn-1");
+  });
+
+  it("falls back to native resolver for non-worktrunk backends", async () => {
+    await expect(
+      resolveTaskWorktreePathForBackend(rootDir, "fn-1", { worktreesDir: "../{repo}.worktrees" } as any, { kind: "native" }, "fusion/fn-1"),
+    ).resolves.toBe(resolve(rootDir, "../repo-name.worktrees/fn-1"));
+  });
 });