Allow configurable .claude/ directory location (support parent directory)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Problem

When running Claude Code from a project subdirectory, the CLI always creates .claude/ inside that project root. This pollutes the project directory with tool infrastructure files (worktrees, plans, sessions).

Other AI CLI tools like Codex store their state folder in a parent directory and work with child projects without creating per-project folders.

Current behavior

Parent dir has .claude/ with memories
Project dir gets its own .claude/ with worktrees, plans, memory redirect

Proposed Solution

Desired behavior

Allow .claude/ to live only in a parent directory with project-specific subfolders (e.g., .claude/worktrees/MyProject/)
Suggested implementation

A setting like "projectStateDir": "parent" in ~/.claude/settings.json

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_