✨ feat(vscode): worktree 改建到 ~/Sources/worktree/<项目>/<slug>，接线 superpowers.worktreeDirectory 配置

实施流程不再硬编码 .claude/worktrees/<hash>：
- worktree 目录名改用 spec/plan 的 slug（specs|plans 后那一级目录名），分支改为 feature/<slug>
- 目录走 superpowers.worktreeDirectory 模板（package.json 新注册配置），支持 $project_root/$project_name/$feature_name 占位符及开头 ~ 展开，默认 ~/Sources/worktree/$project_name/$feature_name
- worktree 现位于工作区外：创建前 mkdir -p 父目录，state/webview 改存绝对路径（下游消费方已兼容 isAbsolute）

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

vscode/src/panel/handlers/sessions.ts

@@ -558,6 +558,48 @@ export async function triggerAutoReviewTab(panel: KanbanWebviewPanel, opts: {
   return true
 }
 
+/**
+ * Derive a human-readable slug from a spec/plan file path.
+ *
+ * spec/plan live as directories on disk
+ * (docs/superpowers/{specs,plans}/<slug>/{spec,plan}.md), so the slug is the
+ * path segment right after the `specs`/`plans` segment — that's the name the
+ * user sees in the tree. Falls back to the parent dir name, then to a stable
+ * 8-char sha256 of the path so the worktree dir name is never empty. Paths
+ * come from gitea body comments and use `/` separators.
+ */
+function deriveSlug(planFile: string): string {
+  const segments = planFile.split('/').filter(Boolean)
+  const anchor = segments.findIndex(s => s === 'plans' || s === 'specs')
+  if (anchor >= 0 && segments[anchor + 1]) {
+    return segments[anchor + 1]
+  }
+  const parent = path.basename(path.dirname(planFile))
+  if (parent && parent !== '.' && parent !== '/') {
+    return parent
+  }
+  return createHash('sha256').update(planFile).digest('hex').slice(0, 8)
+}
+
+/**
+ * Expand the `superpowers.worktreeDirectory` template into an ABSOLUTE path.
+ * Placeholders: $project_root (workspace abs path), $project_name (its
+ * basename), $feature_name (the slug). A leading `~` is expanded here because
+ * git/execFile run without a shell and won't do tilde expansion themselves.
+ * The result is resolved to absolute since the worktree now lives outside the
+ * workspace and is stored/compared as an absolute path downstream.
+ */
+function resolveWorktreeDir(template: string, workspaceRoot: string, slug: string): string {
+  let p = template
+    .split('$project_name').join(path.basename(workspaceRoot))
+    .split('$project_root').join(workspaceRoot)
+    .split('$feature_name').join(slug)
+  if (p.startsWith('~')) {
+    p = path.join(os.homedir(), p.slice(1))
+  }
+  return path.resolve(p)
+}
+
 /**
  * Kick off the end-to-end "implement this plan" flow:
  *   1. Detect repo + token, compute a stable feature_name from the plan path.
@@ -639,10 +681,13 @@ export async function handleImplement(
     return
   }
 
-  const feature = createHash('sha256').update(planFile).digest('hex').slice(0, 8)
-  const branch = `feature/${feature}`
-  const relativeWorktreePath = `.claude/worktrees/${feature}`
-  const worktreePath = path.join(workspaceRoot, relativeWorktreePath)
+  // worktree 目录名用 spec/plan 的 slug（可读、与 spec 目录同名），不再用 planFile 的 hash。
+  const slug = deriveSlug(planFile)
+  const branch = `feature/${slug}`
+  // 目录走 superpowers.worktreeDirectory 模板（设置里可改），默认 ~/Sources/worktree/<项目>/<slug>。
+  const worktreeTemplate = workspace.getConfiguration('superpowers').get<string>('worktreeDirectory')
+    || '~/Sources/worktree/$project_name/$feature_name'
+  const worktreePath = resolveWorktreeDir(worktreeTemplate, workspaceRoot, slug)
 
   // Pre-flight: refuse if either the directory or the branch already
   // exists, since `git worktree add -b` would fail and we'd have to
@@ -677,7 +722,7 @@ export async function handleImplement(
   }
   if (worktreeExists || branchExists) {
     void window.showErrorMessage(
-      `feature ${feature} 的 worktree 或分支已存在，请先清理`,
+      `feature ${slug} 的 worktree 或分支已存在，请先清理`,
     )
     return
   }
@@ -713,6 +758,9 @@ export async function handleImplement(
   // Create the worktree before anything else, so a worktree-add failure
   // doesn't leave half-written state behind.
   try {
+    // worktree 现在建在工作区外（~/Sources/worktree/<项目>/...），父目录可能不存在；
+    // git worktree add 不会创建多层父目录，先补齐。
+    await fsp.mkdir(path.dirname(worktreePath), { recursive: true })
     await createWorktree({ workspaceRoot, worktreePath, branch })
   }
   catch (err) {
@@ -759,7 +807,7 @@ export async function handleImplement(
     await panel.mergeIssueState(issueNumber, {
       column: 'in-progress',
       branch,
-      worktreePath: relativeWorktreePath,
+      worktreePath,
       implementStatus: 'running',
     })
     panel.postMessage({
@@ -768,7 +816,7 @@ export async function handleImplement(
       patch: {
         column: 'in-progress',
         branch,
-        worktreePath: relativeWorktreePath,
+        worktreePath,
         implementStatus: 'running',
         worktreeExists: true,
       },