docs: add CLAUDE.md with project guidance for Claude Code

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## What this repo is
+
+Ansible-driven personal infrastructure as code for Void Linux desktops (`ikaros`, `nymph`), Linux/Windows workstations (`deadalus-*`), and an Ubuntu server (`prometheus`). See `AGENTS.md` for topology and `README.md` for full profile descriptions.
+
+## Validation commands
+
+```bash
+# Minimum before any change
+ansible-playbook ansible/site.yml --syntax-check
+
+# Dry-run per host
+ansible-playbook ansible/site.yml --limit ikaros --check --diff
+ansible-playbook ansible/site.yml --limit nymph --check --diff
+ansible-playbook ansible/site.yml --limit deadalus-ubuntu --check --diff
+ansible-playbook ansible/site.yml --limit deadalus-fedora --check --diff
+ansible-playbook ansible/site.yml --limit deadalus-wsl --check --diff
+ansible-playbook ansible/site.yml --limit prometheus --check --diff
+
+# Linting
+ansible-lint ansible/site.yml
+ansible-lint ansible/roles
+yamllint ansible/
+
+# Tag-scoped dry-run
+ansible-playbook ansible/site.yml --limit ikaros --tags <tag> --check --diff
+
+# Shell scripts
+sh -n scripts/bootstrap_mail.sh && shellcheck scripts/bootstrap_mail.sh
+```
+
+## Architecture
+
+Configuration is composed in layers: `all → OS → profile → host`. Most hosts use `ansible_connection: local`; `deadalus-win` is the PSRP/Windows exception.
+
+`ansible/site.yml` is the sole orchestration entry point — keep it thin. Implementation belongs in roles under `ansible/roles/`.
+
+Variable layering:
+- `ansible/inventory/group_vars/` — OS and profile defaults
+- `ansible/inventory/host_vars/` — host-specific overrides (never put host overrides in group_vars)
+
+Dotfiles under `dotfiles/` mirror the same layer split: `common/`, `desktop/`, `server/`, `workstation/`, then per-host directories (`ikaros/`, `nymph/`).
+
+## Key conventions
+
+- FQCN for all Ansible modules.
+- Prefer declarative modules over `command`/`shell`; when shell is unavoidable, make idempotency explicit.
+- YAML: start with `---`, 2-space indent, file modes quoted as `"0644"`, booleans as booleans.
+- `no_log: true` on any task that handles secrets.
+- Do not restart `emptty` in playbook tasks on active desktop hosts — do it manually via SSH/TTY.
+
+## Void desktop package buckets (keep disjoint)
+
+- `void_packages_base` — system runtime (init, kernel, audio core, networking, firewall, hw daemons)
+- `desktop_common_packages` — WM-agnostic GUI infra (GTK theme, polkit, keyring, portals, flatpak, printing)
+- `desktop_i3_packages` / `desktop_sway_packages` — session-specific binaries; cross-WM packages used by both (`dunst`, `rofi`, `alacritty`) are intentionally duplicated
+- `profile_packages` — cross-distro; do not move desktop-only Void entries into it
+
+Dotfile var split follows the same logic: `desktop_common_dotfiles` (WM-agnostic), `desktop_void_dotfiles` (Void runtime — turnstile services, bash fragments).
+
+## Secrets
+
+- `secrets/vault.yml` and `secrets/vault.local.yml` are loaded conditionally if present.
+- `secrets/.vault_pass.gpg` is used automatically if present; falls back to `secrets/.vault_pass`.
+- Never print vault values; always use `no_log: true` where secrets flow through tasks.
+
+## AI agent dotfiles
+
+Shared agent instructions live in `dotfiles/common/.config/ai/`. Agent-specific entrypoints reference that path rather than duplicating content. Shared npm packages are in `ai_agents_npm_packages` in `ansible/inventory/group_vars/all.yml`.