Engine seam (ScanEngine trait) + Tauri GUI

ClamAV is a temporary dependency. Everything ClamAV-specific moves
behind a 4-method trait in crates/houndd/src/engine.rs:

    trait ScanEngine { name; probe; scan; update }
    struct ClamAvEngine   // today
    const ENGINE          // one-line flip when the native engine lands

- parse_clamscan() is now a pure fn with unit tests (OK/FOUND/INCOMPLETE,
  dedup, malformed lines)
- main.rs drops all clamscan/clamd/freshclam knowledge; Status reports
  engine='clamav' via the trait
- README documents the seam and the wire contract that stays stable

GUI (gui/, Tauri 2, standalone workspace, vanilla JS premium-dark shell):
- system-tray sentinel on the 4-state dog-head ladder (green/amber/red/gray)
  with tooltips; clicks open the window / scan / update
- window: protection hero, path + recursive scan, progress bar, results
  table, signature update log; state mirrored to the tray
- compiles clean (cargo build, 0 warnings) on Mint 22.3 + webkit2gtk-4.1

All 11 workspace tests pass, incl. the E2E EICAR scan over the real
Unix-socket daemon (clamscan finds the planted EICAR).

README.md

@@ -14,7 +14,7 @@ antivirus/
 ├── Cargo.toml              # Rust workspace
 ├── crates/
 │   ├── hound-api/          # shared wire types + socket client (daemon/CLI/GUI all use it)
-│   ├── houndd/             # the daemon: Unix-socket API over ClamAV
+│   ├── houndd/             # the daemon: Unix-socket API over a pluggable engine
 │   └── hound/              # CLI client
 ├── assets/icons/           # dog-head brand mark + 4-state tray ladder
 └── gui/                    # Tauri 2 desktop app (system tray + scan UI)
@@ -25,19 +25,41 @@ antivirus/
 ```
         houndd  (Rust daemon — the engine)
        ┌──────────────────────────────────┐
-       │ L1  ClamAV signatures            │
-       │ L2  Curated threat packs (Pro)   │
-       │ L3  Behavioral monitor (Pro)     │
-       │ L4  Supply-chain checks (Pro)    │
+       │  ScanEngine trait                │
+       │  ├─ L1  ClamAV signatures (now)  │
+       │  ├─ L2  Curated threat packs(Pro)│
+       │  ├─ L3  Behavioral monitor (Pro) │
+       │  └─ L4  Supply-chain checks(Pro) │
        └──────────────┬───────────────────┘
               Unix socket (JSON-RPC, line-delimited)
           ┌───────────┼───────────┐
        hound CLI   GUI (Tauri)   future modules
 ```
 
-The daemon is the only process that touches ClamAV. CLI and GUI are thin
-clients — so future suite tools (firewall, updater, …) plug into the same
-socket.
+The daemon is the only process that touches a scanning engine. CLI and GUI
+are thin clients — so future suite tools (firewall, updater, …) plug into
+the same socket.
+
+### Swapping the engine (the ClamAV seam)
+
+ClamAV is a **temporary** dependency. Everything ClamAV-specific — version
+probe, signature freshness, the `clamscan` subprocess + output parsing,
+`freshclam` — lives in one file behind a four-method trait:
+
+```
+crates/houndd/src/engine.rs
+    trait ScanEngine { name; probe; scan; update }
+    struct ClamAvEngine            // today
+    const ENGINE: ClamAvEngine     // ← flip this line when the native
+                                   //   engine lands; nothing else in the
+                                   //   daemon, CLI, GUI, or wire API moves
+```
+
+The wire stays engine-agnostic: `Status.engine` names the implementation
+(`"clamav"` today) and `Status.db` carries what any signature store has —
+a file name and a timestamp. When our own Rust engine ships, it's a new
+`ScanEngine` implementation, a one-const flip, and the tray/CLI/GUI simply
+start reporting the new engine name.
 
 ## Icon system
 
@@ -89,6 +111,39 @@ cargo run -p hound -- scan /tmp/eicar.com
 # expect: exit code 1, "Eicar-Test-Signature FOUND"
 ```
 
+### Updating signatures
+
+`hound update` wraps `freshclam` (trying `sudo freshclam` first, since
+plain-user runs can't write `/var/lib/clamav` and `/var/log/clamav`). The
+GUI's "Update Signatures" button drives the same RPC and shows the log.
+```sh
+cargo run -p hound -- update        # or: hound update --json
+```
+
+## The GUI (`gui/`)
+
+A Tauri 2 desktop app — a thin view over the *same* `houndd` socket the
+CLI uses (via the shared `hound-api` client), so the window and the
+command line never disagree about your security state.
+
+```
+gui/
+├── dist/            # the front-end (vanilla HTML/CSS/JS, premium dark shell)
+└── src-tauri/       # Tauri 2 shell + system-tray sentinel
+```
+
+The tray sentinel swaps the 4-state icons (green/amber/red/gray) as your
+state changes; the window shows a live protection hero, a scan progress
+bar, a results table, and the signature-update log.
+
+Build it:
+```sh
+cd gui
+npm install
+npm run tauri dev          # dev with hot reload
+npm run tauri build        # → .deb in src-tauri/target/release/bundle/
+```
+
 ## Git conventions
 
 - Branch `main` is deployable; small, focused commits.

gui/.gitignore

@@ -0,0 +1,6 @@
+node_modules/
+dist/assets/
+src-tauri/target/
+src-tauri/gen/
+.DS_Store
+*.log

gui/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "hound-gui",
+  "version": "0.1.0",
+  "description": "Hound Antivirus — desktop app",
+  "type": "module",
+  "scripts": {
+    "tauri": "tauri",
+    "dev": "tauri dev",
+    "build": "tauri build"
+  },
+  "devDependencies": {
+    "@tauri-apps/cli": "^2.5.0"
+  },
+  "dependencies": {
+    "@tauri-apps/api": "^2.5.0"
+  }
+}

gui/src-tauri/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "hound-gui"
+description = "Hound Antivirus desktop app (Tauri 2)"
+version = "0.1.0"
+edition = "2021"
+license = "MIT"
+repository = "https://git.joelovestech.com/Hound/Antivirus"
+
+# Standalone crate: the GUI has its own workspace (different dep set from
+# the CLI/daemon) and is built via `cargo tauri build`, not the root build.
+[workspace]
+
+[dependencies]
+hound-api = { path = "../../crates/hound-api" }
+tauri = { version = "2", features = ["tray-icon", "image-png"] }
+tauri-plugin-dialog = "2"
+tauri-plugin-opener = "2"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+anyhow = "1"
+
+[build-dependencies]
+tauri-build = "2"
+
+[profile.release]
+strip = true

gui/src-tauri/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    tauri_build::build()
+}

gui/src-tauri/src/main.rs

@@ -0,0 +1,222 @@
+//! `hound-gui` — the Tauri 2 desktop app for Hound Antivirus.
+//!
+//! The window is a thin view over the same `houndd` Unix socket the CLI uses.
+//! The system-tray sentinel swaps between the four state icons:
+//!
+//!   protected (green) / scanning (amber) / threat (red) / paused (gray)
+
+use hound_api::{Client, ScanResult, Status, UpdateResult};
+use serde_json::json;
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use tauri::image::Image;
+use tauri::menu::{Menu, MenuItem, PredefinedMenuItem};
+use tauri::tray::{TrayIconBuilder, TrayIconEvent};
+use tauri::{Emitter, Manager, State};
+
+type R<T> = anyhow::Result<T>;
+
+const TRAY_ID: &str = "hound-tray";
+
+/// States the tray can render. Anything unknown falls back to `protected`.
+const STATES: [&str; 4] = ["protected", "scanning", "threat", "paused"];
+
+/// The four preloaded state icons, managed so tray swaps never hit disk.
+#[derive(Default)]
+struct TrayIcons(HashMap<String, Image<'static>>);
+
+fn client() -> Client {
+    Client::default_path()
+}
+
+// ── Commands (window → daemon) ──────────────────────────────────────────────
+
+#[tauri::command]
+async fn status() -> Result<Status, String> {
+    let c = client();
+    tauri::async_runtime::spawn_blocking(move || c.status())
+        .await
+        .map_err(|e| e.to_string())?
+        .map_err(|e| e.to_string())
+}
+
+#[tauri::command]
+async fn scan(path: String, recursive: bool) -> Result<ScanResult, String> {
+    let c = client();
+    tauri::async_runtime::spawn_blocking(move || c.scan(&path, recursive))
+        .await
+        .map_err(|e| e.to_string())?
+        .map_err(|e| e.to_string())
+}
+
+#[tauri::command]
+async fn update() -> Result<UpdateResult, String> {
+    let c = client();
+    tauri::async_runtime::spawn_blocking(move || c.update())
+        .await
+        .map_err(|e| e.to_string())?
+        .map_err(|e| e.to_string())
+}
+
+/// Swap the tray icon + tooltip. The window calls this to keep the sentinel
+/// in step with what the user is doing (e.g. it starts a scan).
+#[tauri::command]
+fn set_state(
+    app: tauri::AppHandle,
+    icons: State<'_, TrayIcons>,
+    state: String,
+) -> Result<(), String> {
+    let state = if STATES.contains(&state.as_str()) {
+        state
+    } else {
+        "protected".into()
+    };
+    let img = icons.0.get(&state).cloned().unwrap_or_else(|| {
+        icons
+            .0
+            .get("protected")
+            .cloned()
+            .expect("protected icon always loaded")
+    });
+    if let Some(tray) = app.tray_by_id(TRAY_ID) {
+        let _ = tray.set_icon(Some(img));
+        let _ = tray.set_tooltip(Some(tooltip_for(&state)));
+    }
+    Ok(())
+}
+
+fn tooltip_for(state: &str) -> String {
+    match state {
+        "threat" => "Hound — threat found".into(),
+        "scanning" => "Hound — scanning…".into(),
+        "paused" => "Hound — paused".into(),
+        _ => "Hound — protected".into(),
+    }
+}
+
+// ── Icon resolution ─────────────────────────────────────────────────────────
+
+fn icon_dir(app: &tauri::AppHandle) -> PathBuf {
+    // Packaged: resources dir. Dev: the repo's assets/icons.
+    if let Ok(dir) = app.path().resource_dir() {
+        let d = dir.join("icons");
+        if d.join("state-protected-22.png").exists() {
+            return d;
+        }
+    }
+    for candidate in [
+        PathBuf::from("icons"),
+        PathBuf::from("../src-tauri/icons"),
+        PathBuf::from("../assets/icons"),
+    ] {
+        if candidate.join("state-protected-22.png").exists() {
+            return candidate;
+        }
+    }
+    PathBuf::from("icons")
+}
+
+fn load_state_icons(app: &tauri::AppHandle) -> R<HashMap<String, Image<'static>>> {
+    let dir = icon_dir(app);
+    let mut icons = HashMap::new();
+    for state in STATES {
+        let path = dir.join(format!("state-{state}-22.png"));
+        icons.insert(state.to_string(), load_icon(&path)?);
+    }
+    Ok(icons)
+}
+
+/// Load a PNG tray icon; Tauri decodes and converts to RGBA for us.
+fn load_icon(path: &Path) -> R<Image<'static>> {
+    Image::from_path(path).map_err(|e| anyhow::anyhow!("loading tray icon {}: {e}", path.display()))
+}
+
+// ── App ─────────────────────────────────────────────────────────────────────
+
+pub fn run() {
+    tauri::Builder::default()
+        .plugin(tauri_plugin_dialog::init())
+        .plugin(tauri_plugin_opener::init())
+        .invoke_handler(tauri::generate_handler![status, scan, update, set_state])
+        .setup(|app| {
+            let handle = app.handle().clone();
+            let icons = TrayIcons(load_state_icons(&handle)?);
+            let initial_icon = icons
+                .0
+                .get("protected")
+                .expect("protected icon loaded")
+                .clone();
+            app.manage(icons);
+
+            let open = MenuItem::with_id(&handle, "open", "Open Hound", true, None::<&str>)?;
+            let scan_home =
+                MenuItem::with_id(&handle, "scan-home", "Scan Home Folder", true, None::<&str>)?;
+            let scan_downloads = MenuItem::with_id(
+                &handle,
+                "scan-downloads",
+                "Scan Downloads",
+                true,
+                None::<&str>,
+            )?;
+            let update_sig =
+                MenuItem::with_id(&handle, "update", "Update Signatures", true, None::<&str>)?;
+            let sep = PredefinedMenuItem::separator(&handle)?;
+            let quit = MenuItem::with_id(&handle, "quit", "Quit", true, None::<&str>)?;
+            let menu = Menu::with_items(
+                &handle,
+                &[&open, &scan_home, &scan_downloads, &update_sig, &sep, &quit],
+            )?;
+
+            let _ = TrayIconBuilder::with_id(TRAY_ID)
+                .icon(initial_icon)
+                .tooltip("Hound — protected")
+                .menu(&menu)
+                .show_menu_on_left_click(false)
+                .on_menu_event(|app, event| {
+                    let id = event.id().as_ref();
+                    let window = match app.get_webview_window("main") {
+                        Some(w) => w,
+                        None => return,
+                    };
+                    match id {
+                        "open" => {
+                            let _ = window.show();
+                            let _ = window.set_focus();
+                        }
+                        "quit" => app.exit(0),
+                        "scan-home" => {
+                            let _ =
+                                window.emit("tray-event", json!({ "action": "scan", "path": "~" }));
+                        }
+                        "scan-downloads" => {
+                            let _ = window.emit(
+                                "tray-event",
+                                json!({ "action": "scan", "path": "~/Downloads" }),
+                            );
+                        }
+                        "update" => {
+                            let _ = window.emit("tray-event", json!({ "action": "update" }));
+                        }
+                        _ => {}
+                    }
+                })
+                .on_tray_icon_event(|tray, event| {
+                    if let TrayIconEvent::Click { .. } = event {
+                        let app = tray.app_handle();
+                        if let Some(window) = app.get_webview_window("main") {
+                            let _ = window.show();
+                            let _ = window.set_focus();
+                        }
+                    }
+                })
+                .build(&handle)?;
+
+            Ok(())
+        })
+        .run(tauri::generate_context!())
+        .expect("error while running Hound");
+}
+
+fn main() {
+    run()
+}

gui/src-tauri/tauri.conf.json

@@ -0,0 +1,43 @@
+{
+  "$schema": "https://schema.tauri.app/config/2",
+  "productName": "Hound Antivirus",
+  "version": "0.1.0",
+  "identifier": "com.joelovestech.hound",
+  "build": {
+    "frontendDist": "../dist",
+    "devUrl": "http://localhost:1420",
+    "beforeDevCommand": "",
+    "beforeBuildCommand": ""
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "Hound Antivirus",
+        "width": 940,
+        "height": 640,
+        "minWidth": 760,
+        "minHeight": 520,
+        "resizable": true,
+        "center": true,
+        "fullscreen": false,
+        "decorations": true
+      }
+    ],
+    "security": {
+      "csp": null
+    },
+    "trayIcon": {
+      "iconPath": "icons/state-protected-22.png",
+      "iconAsTemplate": false
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": ["app", "deb"],
+    "icon": [
+      "icons/hound-48.png",
+      "icons/state-protected-32.png"
+    ],
+    "resources": ["icons/state-protected-22.png", "icons/state-scanning-22.png", "icons/state-threat-22.png", "icons/state-paused-22.png"]
+  }
+}