Add global CLAUDE.md with personal AI agent preferences

[DeadEnglish]

Context

Claude Code automatically reads ~/.claude/CLAUDE.md on every session, injecting it into the system prompt before any project-level CLAUDE.md. This file currently only lists gstack skills — it has no personal preferences or rules. Each AI session starts without knowing the user's defaults, meaning the user repeats the same corrections (no em dashes, no co-author commits) across projects.

Adding a version-controlled CLAUDE.md to the dotfiles repo with a symlink ensures every Claude Code session, in any project, inherits the user's rules without needing project-level repetition. The global file is authoritative — projects cannot override.

Current State

• ~/.claude/CLAUDE.md — exists (648 bytes, 41 lines), contains only gstack skill listings and the /browse routing rule. NOT version-controlled.
• ~/.config/claude/ — does not exist. No Claude-specific config is tracked in dotfiles.
• ~/.config/setup.sh — bootstraps machine (Xcode, Homebrew, zsh, git config) but has no Claude Code setup.
• ~/.config/claude/voice.md — does not exist yet; user will create separately.

Proposed Change

Create ~/.config/claude/CLAUDE.md with global AI agent preferences, symlinked to ~/.claude/CLAUDE.md. Add symlink creation to setup.sh. The new file has two sections: global preferences (always applied) and gstack skills (existing content preserved).

Implementation Details

1. Create ~/.config/claude/CLAUDE.md — 8 global rules plus gstack skill listing:

• No em dashes
• Never modify autogenerated files (changelog.md, etc.)
• Never co-author commits
• One sentence per line in markdown
• Don't over-weight development costs in technical decisions
• Reproduce bugs in E2E before fixing
• Fix lint and test failures even if not caused by current work
• Commit incrementally when completing plans
• Voice reference: "When writing in my voice, read ~/.config/claude/voice.md"

2. Update setup.sh — insert after existing git config block:

# Claude Code global config symlink
CLAUDE_CONFIG_DIR="$HOME/.config/claude"
CLAUDE_TARGET="$HOME/.claude/CLAUDE.md"

# Back up existing ~/.claude/CLAUDE.md if it's a real file (not already a symlink)
if [ -f "$CLAUDE_TARGET" ] && [ ! -L "$CLAUDE_TARGET" ]; then
  cp "$CLAUDE_TARGET" "$CLAUDE_TARGET.backup-$(date +%Y%m%d)"
fi

mkdir -p "$CLAUDE_CONFIG_DIR"
ln -sf "$CLAUDE_CONFIG_DIR/CLAUDE.md" "$CLAUDE_TARGET"

Acceptance Criteria

1. ~/.config/claude/CLAUDE.md exists in the repo with the content specified above
2. Running setup.sh creates ~/.claude/CLAUDE.md as a symlink pointing to ~/.config/claude/CLAUDE.md
3. If ~/.claude/CLAUDE.md already exists as a real file, setup.sh backs it up before overwriting
4. Re-running setup.sh is idempotent — symlink is recreated without errors
5. After setup, cat ~/.claude/CLAUDE.md outputs the content from ~/.config/claude/CLAUDE.md
6. An AI agent session in any project (including projects without their own CLAUDE.md) adheres to all 8 global rules
7. The gstack skill listing is preserved and functional below the global preferences section

Testing Plan

Layer	What	Count
Manual	Run setup.sh on a fresh checkout, verify symlink exists	1
Manual	Modify ~/.claude/CLAUDE.md and verify cat matches source	1
Manual	Re-run setup.sh, verify no double-backup or error	1
Manual	Open Claude Code in a project with no CLAUDE.md, check adherence	1

No automated tests — this is a config file change in a dotfiles repo.

Rollback Plan

Remove the symlink and restore backup:

rm ~/.claude/CLAUDE.md
cp ~/.claude/CLAUDE.md.backup-YYYYMMDD ~/.claude/CLAUDE.md

Or revert the commit in the dotfiles repo and re-run setup.sh.

Effort Estimate

Component	Effort
Create CLAUDE.md	15 min
Update setup.sh	10 min
Manual testing	15 min
Total	~40 min

Files Reference

File	Change
claude/CLAUDE.md	New file — global AI agent preferences + gstack
setup.sh:61	Add symlink creation block after git config

Out of Scope

• Creating voice.md — user handles separately
• Tool-specific config (MCP servers, hooks, permissions, settings.json)
• Any project-level CLAUDE.md changes
• Support for AI agents other than Claude Code