feat: reveal log file from settings; quiet per-tick DHT peer log

The "DHT: got N peers" line fired at info every 20s per torrent and would
dominate the rotated desktop log; drop it to debug.

Add a Logs section to the Sources/settings dialog showing the resolved log
path with a "Reveal in file manager" button, backed by two new Tauri
commands (get_log_path, open_log_file). open_log_file reveals the file via
tauri-plugin-opener (reveal rather than open, so it doesn't depend on a .log
handler); the opener:allow-reveal-item-in-dir permission is granted. The
resolved log path is stored on AppState at construction.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

monsoon-core/src/manager.rs

@@ -1081,7 +1081,7 @@ fn dht_peer_discovery(
     let query = || {
         let all_peers = dht.get_peers(info_hash_id);
         for peers in all_peers {
-            log::info!("DHT: got {} peers", peers.len());
+            log::debug!("DHT: got {} peers", peers.len());
             if cmd_tx.send(Command::ConnectToPeers(peers)).is_err() {
                 return false; // torrent stopped
             }

src-tauri/capabilities/default.json

@@ -6,6 +6,7 @@
     "core:default",
     "dialog:default",
     "notification:default",
-    "opener:default"
+    "opener:default",
+    "opener:allow-reveal-item-in-dir"
   ]
 }

src-tauri/gen/schemas/capabilities.json

@@ -1 +1 @@
-{"default":{"identifier":"default","description":"Default capabilities for Monsoon","local":true,"windows":["main"],"permissions":["core:default","dialog:default","notification:default","opener:default"]}}
+{"default":{"identifier":"default","description":"Default capabilities for Monsoon","local":true,"windows":["main"],"permissions":["core:default","dialog:default","notification:default","opener:default","opener:allow-reveal-item-in-dir"]}}

src-tauri/src/commands.rs

@@ -166,3 +166,21 @@ pub fn remove_remote_server(name: String, state: State<'_, Arc<AppState>>) -> Re
 pub fn take_pending_magnet(state: State<'_, Arc<AppState>>) -> Option<String> {
     state.pending_magnet.lock().ok().and_then(|mut p| p.take())
 }
+
+/// The resolved path to the desktop app's rotating log file, for display.
+#[tauri::command]
+pub fn get_log_path(state: State<'_, Arc<AppState>>) -> String {
+    state.log_file.to_string_lossy().into_owned()
+}
+
+/// Reveal the log file in the system file manager. Revealing (rather than
+/// opening) avoids depending on a `.log` handler being registered.
+#[tauri::command]
+pub fn open_log_file(state: State<'_, Arc<AppState>>) -> Result<(), String> {
+    use tauri_plugin_opener::OpenerExt;
+    state
+        .app
+        .opener()
+        .reveal_item_in_dir(&state.log_file)
+        .map_err(|e| e.to_string())
+}

src-tauri/src/lib.rs

@@ -107,6 +107,7 @@ pub fn run(initial_magnet: Option<String>) {
     let event_rx = manager.event_rx.clone();
 
     let desktop_cfg = desktop_config::DesktopConfig::load();
+    let log_file = paths.log_file.clone();
 
     tauri::Builder::default()
         .plugin(tauri_plugin_dialog::init())
@@ -151,13 +152,15 @@ pub fn run(initial_magnet: Option<String>) {
             commands::add_remote_server,
             commands::remove_remote_server,
             commands::take_pending_magnet,
+            commands::get_log_path,
+            commands::open_log_file,
         ])
         .setup(move |app| {
             let app_handle = app.handle().clone();
 
             // Build and manage the unified AppState (local manager + config
             // + active view). All commands resolve through this.
-            let state = source::AppState::new(manager, desktop_cfg, app_handle.clone());
+            let state = source::AppState::new(manager, desktop_cfg, app_handle.clone(), log_file);
             app.manage(state.clone());
 
             // Scheduler tick for the local manager: independent of the event

src-tauri/src/source.rs

@@ -20,6 +20,8 @@ pub struct AppState {
     /// up yet. Set on first-launch (before the GUI mounts) and as a fallback
     /// for second-instance handoff. Cleared by `take_pending_magnet`.
     pub pending_magnet: Mutex<Option<String>>,
+    /// Resolved path to the rotating log file, surfaced in the UI.
+    pub log_file: std::path::PathBuf,
 }
 
 /// The "currently viewed source" — drives what `get_torrents` returns and
@@ -46,13 +48,19 @@ impl View {
 }
 
 impl AppState {
-    pub fn new(local: TorrentManager, config: DesktopConfig, app: AppHandle) -> Arc<Self> {
+    pub fn new(
+        local: TorrentManager,
+        config: DesktopConfig,
+        app: AppHandle,
+        log_file: std::path::PathBuf,
+    ) -> Arc<Self> {
         Arc::new(Self {
             local: Mutex::new(local),
             config: Mutex::new(config),
             view: AsyncMutex::new(View::local()),
             app,
             pending_magnet: Mutex::new(None),
+            log_file,
         })
     }
 

src/lib/SourcesSettings.svelte

@@ -3,6 +3,8 @@
     addRemoteServer,
     removeRemoteServer,
     setDefaultSource,
+    getLogPath,
+    openLogFile,
   } from "./ipc";
   import { defaultSource, refreshSources, sources } from "./stores";
 
@@ -12,6 +14,22 @@
   let labelInput = $state("");
   let urlInput = $state("");
   let error = $state<string | null>(null);
+  let logPath = $state("");
+
+  $effect(() => {
+    getLogPath()
+      .then((p) => (logPath = p))
+      .catch(() => {});
+  });
+
+  async function revealLog() {
+    error = null;
+    try {
+      await openLogFile();
+    } catch (e) {
+      error = String(e);
+    }
+  }
 
   async function setDefault(id: string) {
     error = null;
@@ -123,6 +141,14 @@
       <button class="primary" onclick={addRemote}>Add</button>
     </div>
 
+    <h3>Logs</h3>
+    <div class="logs">
+      <code class="log-path">{logPath || "…"}</code>
+      <button onclick={revealLog} disabled={!logPath}>
+        Reveal in file manager
+      </button>
+    </div>
+
     {#if error}
       <p class="error">{error}</p>
     {/if}
@@ -262,6 +288,28 @@
     background: rgba(199, 67, 67, 0.1);
   }
 
+  .logs {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+  }
+
+  .log-path {
+    flex: 1;
+    font-size: 12px;
+    color: var(--fg-secondary);
+    background: var(--bg-secondary);
+    padding: 6px 10px;
+    border-radius: var(--radius);
+    overflow-x: auto;
+    white-space: nowrap;
+    user-select: text;
+  }
+
+  .logs button {
+    flex-shrink: 0;
+  }
+
   .error {
     color: #c74343;
     font-size: 13px;

src/lib/ipc.ts

@@ -138,3 +138,13 @@ export async function removeRemoteServer(name: string): Promise<void> {
 export async function takePendingMagnet(): Promise<string | null> {
   return invoke("take_pending_magnet");
 }
+
+/** The resolved path to the desktop app's rotating log file. */
+export async function getLogPath(): Promise<string> {
+  return invoke("get_log_path");
+}
+
+/** Reveal the log file in the system file manager. */
+export async function openLogFile(): Promise<void> {
+  return invoke("open_log_file");
+}