fix: two-user model bug fixes and docs

docs/architecture.md

@@ -47,12 +47,14 @@ vacuum-walld ──→ daemon/handlers/logs.py ──→ sudo journalctl ──
 
 Vacuum Wall uses two distinct system users bridged by a shared group:
 
-- **`vacuum-walld`** (daemon user): Runs the privileged background daemon. Holds the NOPASSWD sudo whitelist for all system-level commands. Owns the project directory and data files. Runs with `NoNewPrivileges=yes` (satisfiable since sudo is called directly by the daemon process).
-- **`vacuum-wall`** (web UI user): Runs the Flask web serving process. Has **zero** sudo access. Communicates with the daemon via a Unix socket at `data/daemon.sock`. Runs with `NoNewPrivileges=yes`.
-- **`vacuum-wall`** (shared group): Both users belong to this group. The daemon socket is owned by `vacuum-walld:vacuum-wall` with mode `0660`, allowing the web UI user to connect via group permission. The project directory is owned by `vacuum-walld:vacuum-wall` with group-read+execute, giving the web UI user read access to configs and shared files.
+- **`vacuum-walld`** (daemon user): Runs the privileged background daemon. Holds the NOPASSWD sudo whitelist for all system-level commands. Runs with `NoNewPrivileges=yes` (satisfiable since sudo is called directly by the daemon process).
+- **WebUI user** (default: repo owner in `--dev` mode): Runs the Flask web serving process. Has **zero** sudo access. Communicates with the daemon via a Unix socket at `data/daemon.sock`. Runs with `NoNewPrivileges=yes`.
+- **Shared group**: Both users share the WebUI user's primary group. The daemon socket is owned by `vacuum-walld:<group>` with mode `0660`, allowing the web UI user to connect via group permission. The project directory is owned by the WebUI user with group-read+execute, giving the daemon read access to configs and shared files.
 
 This design isolates privilege escalation entirely within the daemon, so a compromised Flask process cannot invoke sudo directly. The `lib/` modules no longer contain sudo calls; all privileged command execution lives in `daemon/handlers/*.py`.
 
+**Dev mode variant**: When `install.sh --dev` is used, the repo owner (e.g., `wall`) becomes the WebUI user. The project directory remains owned by the repo owner, preserving git operations and code editing. The daemon user (`vacuum-walld`) has the repo owner's primary group as its own primary group, granting read access to project files. All subdirectories carry the setgid bit (`g+s`) so new files inherit the group regardless of the creator's primary group.
+
 The `lib/` modules auto-discover the project root at runtime via `Path(__file__).resolve().parent.parent`. This works because `install.sh` performs an editable pip install (`pip install -e .`), keeping module files in the project directory rather than copying them to `site-packages/`.
 
 ## Install-Time Templating
@@ -61,7 +63,6 @@ System configuration files in `system/` are Jinja2 templates rendered by `instal
 
 - **`systemd/vacuum-wall.service`**, **`systemd/vacuum-walld.service`**, **`systemd/vacuum-wall-acme.service`** — `{{ USER_NAME }}`, `{{ USER_DAEMON_NAME }}`, `{{ USER_GROUP }}`, `{{ PROJECT_DIR }}`, `{{ ACME_HOME }}` are substituted to produce the final systemd unit files installed to `/etc/systemd/system/`. The `PROJECT_DIR` template variable is set from the `INSTALL_DIR` environment variable (defaults to the repo root).
 - **`sudoers.d/vacuum-walld`** — `{{ USER_DAEMON_NAME }}` is substituted to produce the sudoers whitelist for the daemon user.
-- **`sudoers.d/vacuum-wall`** — Reserved for the WebUI user; currently contains no sudo rules (privilege escalation is handled entirely by the daemon).
 - The timer file (`vacuum-wall-acme.timer`) contains no variable paths and is installed as-is.
 
 Runtime templates (`system/nginx/*.conf`, `system/dnsmasq.conf`, `system/wireguard*.conf`) are rendered at runtime by `lib/` modules via Jinja2 with Python data.
@@ -127,7 +128,7 @@ The following file system locations are used for integration with system service
 | `/etc/nginx/snippets/vacuum-wall-ssl.conf` | Shared SSL configuration snippet (protocols, ciphers, DH parameters, OCSP). Included by all HTTPS server blocks. | Vacuum Wall (lib/nginx.py) |
 | `/etc/dnsmasq.d/vacuum-wall.conf` | Generated dnsmasq configuration file. Written from `config/dnsmasq/config.json`. | Vacuum Wall (lib/dnsmasq.py) |
 | `/etc/wireguard/wg0.conf` | Generated WireGuard interface configuration. Written from `config/wireguard/config.json`. | Vacuum Wall (lib/wireguard.py) |
-| `/etc/sudoers.d/vacuum-wall` | Sudo whitelist for the configured system user. Defines all permitted privilege escalations. | Install script (rendered from Jinja2 template) |
+| `/etc/sudoers.d/vacuum-walld` | Sudo whitelist for the daemon user. Defines all permitted privilege escalations. | Install script (rendered from Jinja2 template) |
 
 The `/etc/nginx/conf.d/vacuum-wall.conf` include file ensures that all domain-specific configurations in `sites-enabled/` are loaded by nginx without modifying the main `nginx.conf`. The SSL snippet keeps TLS settings consistent across all managed domains and allows global updates from a single location.