fix(tasktree): normalize backup worktree path

internal/tasktree/backup-contracts.test.ts

@@ -1,7 +1,7 @@
 import assert from "node:assert/strict";
 import { mkdtempSync, readFileSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { join, relative } from "node:path";
 import { test } from "bun:test";
 
 import {
@@ -110,7 +110,7 @@ test("TaskTree restore diff reports create, update, and delete independently", (
   assert.deepEqual(restoreDiff(snapshot, incoming).tasks, { create: 1, update: 1, delete: 1 });
 });
 
-test("TaskTree Git backup publishes once and deduplicates identical content", async () => {
+test("TaskTree Git backup accepts a relative worktree path and deduplicates identical content", async () => {
   const root = mkdtempSync(join(tmpdir(), "tasktree-backup-test-"));
   const remote = join(root, "remote.git");
   const worktree = join(root, "worktree");
@@ -121,7 +121,7 @@ test("TaskTree Git backup publishes once and deduplicates identical content", as
       repoSshUrl: remote,
       branch: "main",
       basePath: "tasktree/test",
-      worktreePath: worktree,
+      worktreePath: relative(process.cwd(), worktree),
       target: "test",
       sshCommand: "",
       authorName: "TaskTree Test",

internal/tasktree/backup-git.ts

@@ -34,7 +34,14 @@ export type PublishedTaskTreeBackup = {
 let gitQueue: Promise<unknown> = Promise.resolve();
 
 export class TaskTreeGitBackup {
-  constructor(readonly config: TaskTreeGitBackupConfig) {}
+  readonly config: TaskTreeGitBackupConfig;
+
+  constructor(config: TaskTreeGitBackupConfig) {
+    this.config = {
+      ...config,
+      worktreePath: resolve(config.worktreePath),
+    };
+  }
 
   async publish(snapshot: TaskTreeSnapshot, reason: string): Promise<PublishedTaskTreeBackup> {
     return enqueueGit(async () => {