[BUG] Worktree-session feature doesn't carry project-scoped MCP config/auth from originalCwd to worktreePath

Preflight

• [x] Searched existing issues; distinct from #58226 (.mcp.json discovery) and #32220 (EnterWorktree reinit). Both closed without addressing parent-session MCP/auth inheritance.
• [x] Single bug.
• [x] Latest version.

What's Wrong

When Claude Code's worktree-session feature spawns a child session (the one with the worktree-state jsonl record), the child is filed under ~/.claude/projects/<sanitized-worktreePath>/ and looks up MCP config via ~/.claude.json → .projects[<worktreePath>]. The parent session's MCP config (under .projects[<originalCwd>]) doesn't propagate, and any project-scoped OAuth credentials granted under the originalCwd identity aren't accessible.

Result: MCP servers visible and authenticated in the parent session are missing or unauthenticated in the child worktree session.

Steps to Reproduce

1. From /home/user/projects/my-repo, run claude; configure a project-scoped OAuth MCP server (e.g. claude mcp add clickup --transport http https://mcp.clickup.com/mcp); complete the OAuth flow.
2. Verify it works in this parent session via /mcp and a tool call.
3. From within that session, enter a worktree via Claude Code's worktree-session feature (EnterWorktree tool / /worktree command / equivalent).
4. The child session's first jsonl record contains:

``json
{
"type": "worktree-state",
"worktreeSession": {
"originalCwd": "/home/user/projects/my-repo",
"worktreePath": "/home/user/projects/my-repo/.claude/worktrees/<name>",
"originalBranch": "<parent-branch>",
"sessionId": "<parent-session-uuid>"
},
"sessionId": "<child-session-uuid>"
}
``

1. /mcp in the child session shows the server is unconfigured/unauthenticated for this scope. Tool calls fail or re-trigger OAuth.

Expected

Worktree-session transitions should treat the originalCwd's .projects[…] entry as the inherited base for MCP config and OAuth state. Either copy on transition, or resolve mcpServers and credentials via worktreeSession.originalCwd rather than current cwd.

Actual

Worktree-session child is keyed by worktreePath. No inheritance from originalCwd. User must reconfigure and re-authenticate per worktree.

Evidence

The session jsonl record type: "worktree-state" ties parent session, worktreePath, and originalCwd together — Claude Code already knows the originalCwd at child-session start. The information needed to do the inheritance is right there in the record; it's just not used for MCP resolution.

Verified locally:

• Parent session at originalCwd has ~/.claude.json .projects["<originalCwd>"].mcpServers = { clickup: {...} } populated and working.
• Child worktree session has ~/.claude.json .projects["<worktreePath>"] entry missing entirely.
• Recent sessions across multiple repos: only the worktree-session child has the divergent project key; all sibling sessions are filed under the main path and work normally.

Impact

For developers using worktrees as their primary parallel-work mechanism (Claude Code's own tooling encourages this), every new worktree-session triggers a re-auth dialog for each project-scoped OAuth MCP server. Scales as O(repos × concurrent worktrees) of redundant OAuth flows.

User-global remote MCP servers (claude.ai family — Gmail, Calendar, Drive) work correctly across worktree transitions because they're not project-scoped. Only project-scoped servers exhibit this.

Related

• #58226 (closed) — .mcp.json discovery in worktree checkout; distinct from this issue.
• #32220 (closed) — EnterWorktree mid-session reinit for path-sensitive MCPs; related but doesn't cover parent-session MCP/auth inheritance specifically.
• Both leave the worktree-session ⇄ originalCwd inheritance gap untouched, which is the root cause for project-scoped MCP servers.