app: debounce channel tree and cache render width

Tab cycles focus to sidebar where Up/Down navigates channels
and Enter joins the selected one. Muted/deafened users show
status symbols in the channel tree.

README.md

@@ -8,6 +8,28 @@ TUI Mumble client with voice support and push-to-talk.
 - Voice transmission with Opus codec
 - Push-to-talk via Kitty keyboard protocol, evdev, or toggle
 - Channel browsing and text chat
+- Chat input history (Up/Down arrow navigation)
+- Self-deafen toggle
+- Volume control (input/output gain)
+- Client certificate authentication
+- Auto-reconnect on network loss
+- Config hot-reload (F5)
+
+## Key Bindings
+
+| Key | Action |
+|-----|--------|
+| `Tab` | Cycle focus (chat input / channel tree) |
+| `F1` | Toggle self-deafen |
+| `F2` | Cycle output volume |
+| `F3` | Cycle input volume |
+| `F4` | Push-to-talk (configurable) |
+| `F5` | Reload config from disk |
+| `Enter` | Send message / join channel (sidebar) |
+| `Up` | Previous message (input) / previous channel (sidebar) |
+| `Down` | Next message (input) / next channel (sidebar) |
+| `q` | Quit |
+| `Ctrl+C` | Quit |
 
 ## Quick Start
 
@@ -29,9 +51,15 @@ mkdir -p ~/.config/tuimble
 host = "mumble.example.com"
 port = 64738
 username = "myname"
+# certfile = "/path/to/cert.pem"
+# keyfile = "/path/to/key.pem"
+
+[audio]
+# output_gain = 1.0
+# input_gain = 1.0
 
 [ptt]
-key = "space"
+key = "f4"
 mode = "hold"
 backend = "auto"
 ```

ROADMAP.md

@@ -18,15 +18,15 @@
 ## Phase 3 — Polish
 
 - [x] Responsive terminal layout (adaptive sidebar, truncation, resize)
-- [ ] Channel tree navigation
+- [x] Channel tree navigation
-- [ ] User list with status indicators
+- [x] User list with status indicators
-- [ ] Volume control
+- [x] Volume control
-- [ ] Server certificate handling
+- [x] Server certificate handling
-- [ ] Config file hot-reload
+- [x] Config file hot-reload
 
 ## Phase 4 — Robustness
 
-- [ ] Reconnection handling
+- [x] Reconnection handling
-- [ ] Error recovery
+- [x] Error recovery
 - [ ] Audio device hot-swap
 - [ ] Comprehensive test suite

TASKLIST.md

@@ -7,8 +7,14 @@
 - [x] Channel tree population from server data
 - [x] Audio pipeline integration with MumbleClient
 - [x] PTT wiring (key events -> audio.capturing toggle)
+- [x] Chat input history navigation (up/down arrows)
+- [x] Channel navigation and join from sidebar
+- [x] User status indicators (mute/deaf)
+- [x] Volume control (F2/F3, gain 0.0-2.0, status bar display)
+- [x] Server certificate handling (certfile/keyfile config)
+- [x] Config file hot-reload (F5, safe/restart change detection)
+- [x] Reconnection handling with auto-retry and backoff
 
 ## Pending
 
-- [ ] Channel join/navigation (select channel in tree, move into it)
+- [ ] Audio device hot-swap
-- [ ] Reconnection handling on disconnect

docs/CHEATSHEET.md

@@ -6,7 +6,13 @@ make run             launch tuimble
 make test            run tests
 make lint            check code style
 
+F1                   toggle self-deafen
+F2                   cycle output volume
+F3                   cycle input volume
+F4                   push-to-talk
+F5                   reload config
+Tab                  cycle focus
+Enter                send message / join channel
+Up/Down              history / channel navigation
 q                    quit
-space                push-to-talk (hold)
-Enter                send message
 ```

docs/DEBUG.md

@@ -38,8 +38,46 @@ groups                           # should include 'input'
 
 Add user to `input` group: `sudo usermod -aG input $USER`
 
+### Certificate errors
+
+If the server requires client certificates:
+
+```sh
+# Verify cert/key pair
+openssl x509 -in cert.pem -noout -subject -dates
+openssl rsa -in key.pem -check -noout
+```
+
+- Both `certfile` and `keyfile` must be PEM-encoded
+- Paths must be absolute or relative to the working directory
+- Key must not be passphrase-protected (pymumble limitation)
+- If the server uses a self-signed CA, pymumble verifies by default
+
 ### Connection refused
 
 - Verify server address and port
 - Check firewall allows outbound TCP/UDP to port 64738
 - Test with: `nc -zv <host> 64738`
+
+### Connection drops / reconnection
+
+When tuimble loses connection, it retries automatically with backoff.
+The chatlog shows each attempt:
+
+```
+✗ disconnected from server
+reconnecting in 2s (attempt 1/10)...
+✗ attempt 1: network error: [Errno 111] Connection refused
+reconnecting in 4s (attempt 2/10)...
+✓ connected as myname
+```
+
+Common causes:
+
+- **Server restart** — normal, reconnect succeeds when server is back
+- **Network loss** — check connectivity, tuimble retries automatically
+- **Auth timeout** — server may drop idle connections; reconnect handles this
+- **"rejected" with no retry** — wrong password or certificate issue
+
+If reconnection fails after 10 attempts, press `F5` to retry manually.
+Update `config.toml` if server details changed.

docs/USAGE.md

@@ -11,11 +11,15 @@ tuimble --host mumble.example.com --user myname
 
 | Key | Action |
 |-----|--------|
+| `Tab` | Cycle focus (chat input / channel tree) |
 | `F1` | Toggle self-deafen |
+| `F2` | Cycle output volume |
+| `F3` | Cycle input volume |
 | `F4` | Push-to-talk (configurable) |
-| `Enter` | Send message |
+| `F5` | Reload config from disk |
-| `Up` | Previous sent message (in chat input) |
+| `Enter` | Send message / join channel (sidebar) |
-| `Down` | Next sent message (in chat input) |
+| `Up` | Previous message (input) / previous channel (sidebar) |
+| `Down` | Next message (input) / next channel (sidebar) |
 | `q` | Quit |
 | `Ctrl+C` | Quit |
 
@@ -44,6 +48,56 @@ python3 -m pstats /tmp/tuimble.prof   # interactive explorer
 Note: cProfile captures the main thread only. Background workers
 started with `@work(thread=True)` are not included.
 
+## Volume Control
+
+`F2` and `F3` cycle through volume steps: 0%, 25%, 50%, 75%, 100%,
+125%, 150%, 200%, then back to 0%. Volume is shown in the status bar
+as block indicators.
+
+```toml
+[audio]
+output_gain = 0.75   # 0.0 to 2.0 (default 1.0)
+input_gain = 1.5     # 0.0 to 2.0 (default 1.0)
+```
+
+## Client Certificates
+
+For servers requiring client certificate authentication:
+
+```toml
+[server]
+certfile = "/path/to/client-cert.pem"
+keyfile = "/path/to/client-key.pem"
+```
+
+Both must be PEM-encoded. Leave empty to connect without a certificate.
+
+## Config Reload
+
+`F5` reloads `~/.config/tuimble/config.toml` from disk.
+
+**Safe changes** (applied immediately): PTT key/mode/backend, audio
+gain values.
+
+**Restart-requiring changes** (server settings, audio device/rate):
+shown as warnings. Press `F5` again to confirm reconnect, or any
+other key to cancel.
+
+## Reconnection
+
+On unexpected disconnect (server restart, network loss), tuimble
+automatically retries with exponential backoff:
+
+- Initial delay: 2 seconds, doubling each attempt (2, 4, 8, 16, 30...)
+- Maximum delay: 30 seconds
+- Maximum attempts: 10
+
+The status bar shows `◐ reconnecting` during retry. If the server
+rejects authentication, retries stop immediately.
+
+After all attempts are exhausted, press `F5` to retry manually.
+`F5` also cancels an in-progress reconnect and starts a fresh attempt.
+
 ## Configuration
 
 See `~/.config/tuimble/config.toml`. All fields are optional;

src/tuimble/app.py

@@ -14,12 +14,27 @@ from textual.reactive import reactive
 from textual.widgets import Footer, Header, Input, RichLog, Static
 
 from tuimble.audio import AudioPipeline
-from tuimble.client import Channel, MumbleClient
+from tuimble.client import Channel, ConnectionFailed, MumbleClient, User
 from tuimble.config import Config, load_config
 from tuimble.ptt import KittyPtt, TogglePtt, detect_backend
 
 log = logging.getLogger(__name__)
 
+VOLUME_STEPS = (0.0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 2.0)
+
+RECONNECT_INITIAL = 2    # seconds before first retry
+RECONNECT_MAX = 30       # maximum backoff delay
+RECONNECT_RETRIES = 10   # attempts before giving up
+TREE_DEBOUNCE = 0.1      # seconds to coalesce state changes
+
+
+def _next_volume(current: float) -> float:
+    """Cycle through VOLUME_STEPS, wrapping to 0.0 after max."""
+    for step in VOLUME_STEPS:
+        if step > current + 0.01:
+            return step
+    return VOLUME_STEPS[0]
+
 
 # -- custom messages (pymumble thread -> Textual) ----------------------------
 
@@ -45,6 +60,14 @@ class ServerStateChanged(Message):
     pass
 
 
+class ChannelSelected(Message):
+    """User selected a channel to join."""
+
+    def __init__(self, channel_id: int) -> None:
+        super().__init__()
+        self.channel_id = channel_id
+
+
 # -- widgets -----------------------------------------------------------------
 
 
@@ -53,8 +76,17 @@ class StatusBar(Static):
 
     ptt_active = reactive(False)
     connected = reactive(False)
+    reconnecting = reactive(False)
     self_deaf = reactive(False)
     server_info = reactive("")
+    output_vol = reactive(100)
+    input_vol = reactive(100)
+
+    @staticmethod
+    def _vol_bar(pct: int) -> str:
+        """Compact 4-char volume indicator using block chars."""
+        filled = round(pct / 25)
+        return "\u2588" * filled + "\u2591" * (4 - filled)
 
     def render(self) -> str:
         w = self.content_size.width if self.content_size.width > 0 else 80
@@ -62,6 +94,9 @@ class StatusBar(Static):
         if self.connected:
             conn_sym = "[#9ece6a]\u25cf[/]"
             conn_full = f"{conn_sym} connected"
+        elif self.reconnecting:
+            conn_sym = "[#e0af68]\u25d0[/]"
+            conn_full = f"{conn_sym} reconnecting"
         else:
             conn_sym = "[#f7768e]\u25cb[/]"
             conn_full = f"{conn_sym} disconnected"
@@ -80,36 +115,79 @@ class StatusBar(Static):
             return f" {conn_sym} {deaf_sym}{ptt_sym}"
         if w < 60:
             return f" {conn_full}  {deaf_full}{'  ' if deaf_full else ''}{ptt_full}"
+
+        vol = (
+            f"  [dim]out[/]{self._vol_bar(self.output_vol)}"
+            f" [dim]in[/]{self._vol_bar(self.input_vol)}"
+        )
         info = f"  [dim]{self.server_info}[/]" if self.server_info else ""
-        return f" {conn_full}  {deaf_full}{'  ' if deaf_full else ''}{ptt_full}{info}"
+        deaf = f"{deaf_full}  " if deaf_full else ""
+        return f" {conn_full}  {deaf}{ptt_full}{vol}{info}"
 
 
 class ChannelTree(Static):
-    """Channel and user list."""
+    """Channel and user list with keyboard navigation."""
 
     DEFAULT_WIDTH = 24
+    can_focus = True
 
     def __init__(self, **kwargs) -> None:
         super().__init__(**kwargs)
         self._channels: dict[int, Channel] = {}
-        self._users_by_channel: dict[int, list[str]] = {}
+        self._users_by_channel: dict[int, list[User]] = {}
+        self._channel_ids: list[int] = []
+        self._focused_idx: int = 0
+        self._my_channel_id: int | None = None
 
     def set_state(
         self,
         channels: dict[int, Channel],
-        users_by_channel: dict[int, list[str]],
+        users_by_channel: dict[int, list[User]],
+        my_channel_id: int | None = None,
     ) -> None:
         self._channels = channels
         self._users_by_channel = users_by_channel
+        self._my_channel_id = my_channel_id
+        self._channel_ids = self._build_channel_order()
+        if self._channel_ids:
+            self._focused_idx = max(
+                0, min(self._focused_idx, len(self._channel_ids) - 1)
+            )
+        else:
+            self._focused_idx = 0
         self.refresh()
 
     def clear_state(self) -> None:
         self._channels = {}
         self._users_by_channel = {}
+        self._channel_ids = []
+        self._focused_idx = 0
+        self._my_channel_id = None
         self.refresh()
 
-    @property
+    def _build_channel_order(self) -> list[int]:
-    def _available_width(self) -> int:
+        """Build flat list of channel IDs in tree order."""
+        if not self._channels:
+            return []
+        order: list[int] = []
+        root_id = self._find_root()
+        self._collect_order(root_id, order)
+        return order
+
+    def _collect_order(self, channel_id: int, order: list[int]) -> None:
+        ch = self._channels.get(channel_id)
+        if ch is None:
+            return
+        order.append(channel_id)
+        children = sorted(
+            (c for c in self._channels.values()
+             if c.parent_id == channel_id and c.channel_id != channel_id),
+            key=lambda c: c.name,
+        )
+        for child in children:
+            self._collect_order(child.channel_id, order)
+
+    def _get_width(self) -> int:
         """Usable character width (content area, excludes padding/border)."""
         w = self.content_size.width
         if w <= 0:
@@ -127,13 +205,23 @@ class ChannelTree(Static):
             return text[:max_width]
         return text[: max_width - 3] + "..."
 
+    @staticmethod
+    def _user_status(user: User) -> str:
+        """Return status indicator for a user."""
+        if user.self_deaf or user.deaf:
+            return " [#f7768e]\u2298[/]"
+        if user.self_mute or user.mute:
+            return " [#e0af68]\u2715[/]"
+        return ""
+
     def render(self) -> str:
         if not self._channels:
             return " Channels\n [dim]\u2514\u2500 (not connected)[/]"
 
+        w = self._get_width()
         lines = [" [bold]Channels[/]"]
         root_id = self._find_root()
-        self._render_tree(root_id, lines, indent=1, is_last=True)
+        self._render_tree(root_id, lines, indent=1, is_last=True, w=w)
         return "\n".join(lines)
 
     def _find_root(self) -> int:
@@ -148,18 +236,37 @@ class ChannelTree(Static):
         lines: list[str],
         indent: int,
         is_last: bool,
+        w: int,
     ) -> None:
         ch = self._channels.get(channel_id)
         if ch is None:
             return
-
-        w = self._available_width
         prefix = " " * indent
         branch = "\u2514\u2500" if is_last else "\u251c\u2500"
-        # indent + 2 branch chars + 1 space
+
-        name_max = w - indent - 3
+        is_current = channel_id == self._my_channel_id
+        is_focused = (
+            self.has_focus
+            and self._channel_ids
+            and self._focused_idx < len(self._channel_ids)
+            and self._channel_ids[self._focused_idx] == channel_id
+        )
+
+        marker = "\u25cf " if is_current else "  "
+        # indent + 2 branch + 1 space + 2 marker
+        name_max = w - indent - 5
         name = self._truncate(ch.name, name_max)
-        lines.append(f"{prefix}{branch} [bold]{name}[/]")
+
+        if is_focused:
+            lines.append(
+                f"{prefix}{branch} {marker}[reverse bold]{name}[/]"
+            )
+        elif is_current:
+            lines.append(
+                f"{prefix}{branch} {marker}[bold #9ece6a]{name}[/]"
+            )
+        else:
+            lines.append(f"{prefix}{branch} {marker}[bold]{name}[/]")
 
         users = self._users_by_channel.get(channel_id, [])
         children = [
@@ -171,12 +278,15 @@ class ChannelTree(Static):
         sub_indent = indent + 2
         sub_prefix = " " * sub_indent
         # sub_indent + 2 bullet chars + 1 space
-        user_max = w - sub_indent - 3
+        user_max = w - sub_indent - 5
-        for i, user_name in enumerate(users):
+        for i, user in enumerate(users):
             is_last_item = i == len(users) - 1 and not children
             bullet = "\u2514\u2500" if is_last_item else "\u251c\u2500"
-            uname = self._truncate(user_name, user_max)
+            uname = self._truncate(user.name, user_max)
-            lines.append(f"{sub_prefix}{bullet} [#7aa2f7]{uname}[/]")
+            status = self._user_status(user)
+            lines.append(
+                f"{sub_prefix}{bullet} [#7aa2f7]{uname}[/]{status}"
+            )
 
         for i, child in enumerate(children):
             self._render_tree(
@@ -184,8 +294,30 @@ class ChannelTree(Static):
                 lines,
                 indent + 2,
                 is_last=i == len(children) - 1,
+                w=w,
             )
 
+    def on_key(self, event: events.Key) -> None:
+        if not self._channel_ids:
+            return
+        if event.key == "up":
+            self._focused_idx = max(0, self._focused_idx - 1)
+            self.refresh()
+            event.prevent_default()
+            event.stop()
+        elif event.key == "down":
+            self._focused_idx = min(
+                len(self._channel_ids) - 1, self._focused_idx + 1
+            )
+            self.refresh()
+            event.prevent_default()
+            event.stop()
+        elif event.key == "enter":
+            cid = self._channel_ids[self._focused_idx]
+            self.post_message(ChannelSelected(cid))
+            event.prevent_default()
+            event.stop()
+
 
 class ChatLog(RichLog):
     """Message log."""
@@ -215,6 +347,9 @@ class TuimbleApp(App):
         padding: 0 1;
         overflow-x: hidden;
     }
+    #sidebar:focus {
+        border-right: solid #7aa2f7;
+    }
     #chat-area {
         width: 1fr;
     }
@@ -243,6 +378,9 @@ class TuimbleApp(App):
 
     BINDINGS = [
         ("f1", "toggle_deaf", "Deafen"),
+        ("f2", "cycle_output_volume", "Vol Out"),
+        ("f3", "cycle_input_volume", "Vol In"),
+        ("f5", "reload_config", "Reload"),
         ("q", "quit", "Quit"),
         ("ctrl+c", "quit", "Quit"),
     ]
@@ -259,6 +397,8 @@ class TuimbleApp(App):
             port=srv.port,
             username=srv.username,
             password=srv.password,
+            certfile=srv.certfile,
+            keyfile=srv.keyfile,
         )
         self._history: list[str] = []
         self._history_idx: int = -1
@@ -270,6 +410,13 @@ class TuimbleApp(App):
             input_device=acfg.input_device,
             output_device=acfg.output_device,
         )
+        self._audio.input_gain = acfg.input_gain
+        self._audio.output_gain = acfg.output_gain
+        self._pending_reload: Config | None = None
+        self._tree_refresh_timer = None
+        self._reconnecting: bool = False
+        self._reconnect_attempt: int = 0
+        self._intentional_disconnect: bool = False
 
     def compose(self) -> ComposeResult:
         yield Header()
@@ -282,6 +429,10 @@ class TuimbleApp(App):
         yield Footer()
 
     def on_mount(self) -> None:
+        status = self.query_one("#status", StatusBar)
+        status.output_vol = int(self._audio.output_gain * 100)
+        status.input_vol = int(self._audio.input_gain * 100)
+
         chatlog = self.query_one("#chatlog", ChatLog)
         chatlog.write("[dim]tuimble v0.1.0[/dim]")
         srv = self._config.server
@@ -290,8 +441,8 @@ class TuimbleApp(App):
 
     # -- server connection (worker thread) -----------------------------------
 
-    @work(thread=True)
+    def _wire_client_callbacks(self) -> None:
-    def _connect_to_server(self) -> None:
+        """Wire pymumble callbacks to message dispatchers."""
         self._client.set_dispatcher(self.call_from_thread)
         self._client.on_connected = self._cb_connected
         self._client.on_disconnected = self._cb_disconnected
@@ -300,6 +451,9 @@ class TuimbleApp(App):
         self._client.on_channel_update = self._cb_state_changed
         self._client.on_sound_received = self._cb_sound_received
 
+    @work(thread=True)
+    def _connect_to_server(self) -> None:
+        self._wire_client_callbacks()
         try:
             self._client.connect()
         except Exception as exc:
@@ -324,10 +478,112 @@ class TuimbleApp(App):
         chatlog = self.query_one("#chatlog", ChatLog)
         chatlog.write(f"[#f7768e]\u2717 {text}[/]")
 
+    # -- auto-reconnect ------------------------------------------------------
+
+    @work(thread=True)
+    def _reconnect_loop(self) -> None:
+        """Retry connection with exponential backoff."""
+        while self._reconnecting:
+            self._reconnect_attempt += 1
+            delay = min(
+                RECONNECT_INITIAL * (2 ** (self._reconnect_attempt - 1)),
+                RECONNECT_MAX,
+            )
+            self.call_from_thread(
+                self._log_reconnect, self._reconnect_attempt, delay,
+            )
+
+            elapsed = 0.0
+            while elapsed < delay and self._reconnecting:
+                time.sleep(0.5)
+                elapsed += 0.5
+
+            if not self._reconnecting:
+                break
+
+            try:
+                self._client.disconnect()
+                srv = self._config.server
+                self._client = MumbleClient(
+                    host=srv.host,
+                    port=srv.port,
+                    username=srv.username,
+                    password=srv.password,
+                    certfile=srv.certfile,
+                    keyfile=srv.keyfile,
+                )
+                self._wire_client_callbacks()
+                self._client.connect()
+
+                self._reconnecting = False
+                self._reconnect_attempt = 0
+                self.call_from_thread(self._on_reconnect_success)
+                return
+            except ConnectionFailed as exc:
+                if not exc.retryable:
+                    self.call_from_thread(
+                        self._show_error, f"rejected: {exc}",
+                    )
+                    self._reconnecting = False
+                    self.call_from_thread(self._on_reconnect_exhausted)
+                    return
+                self.call_from_thread(
+                    self._show_error,
+                    f"attempt {self._reconnect_attempt}: {exc}",
+                )
+            except Exception as exc:
+                self.call_from_thread(
+                    self._show_error,
+                    f"attempt {self._reconnect_attempt}: {exc}",
+                )
+
+            if self._reconnect_attempt >= RECONNECT_RETRIES:
+                self._reconnecting = False
+                self.call_from_thread(self._on_reconnect_exhausted)
+                return
+
+    def _log_reconnect(self, attempt: int, delay: int) -> None:
+        """Log reconnection attempt to chatlog."""
+        status = self.query_one("#status", StatusBar)
+        status.reconnecting = True
+        chatlog = self.query_one("#chatlog", ChatLog)
+        chatlog.write(
+            f"[dim]reconnecting in {delay}s "
+            f"(attempt {attempt}/{RECONNECT_RETRIES})...[/dim]"
+        )
+
+    def _on_reconnect_success(self) -> None:
+        """Handle successful reconnection."""
+        self.post_message(ServerConnected())
+
+    def _on_reconnect_exhausted(self) -> None:
+        """Handle all reconnection attempts exhausted."""
+        status = self.query_one("#status", StatusBar)
+        status.reconnecting = False
+        chatlog = self.query_one("#chatlog", ChatLog)
+        chatlog.write(
+            f"[#f7768e]reconnection failed after "
+            f"{RECONNECT_RETRIES} attempts[/]"
+        )
+        chatlog.write("[dim]press F5 to retry manually[/dim]")
+
+    def _cancel_reconnect(self) -> None:
+        """Cancel an in-progress reconnect loop."""
+        self._reconnecting = False
+        self._reconnect_attempt = 0
+        try:
+            status = self.query_one("#status", StatusBar)
+            status.reconnecting = False
+        except Exception:
+            pass
+
     # -- message handlers ----------------------------------------------------
 
     def on_server_connected(self, _msg: ServerConnected) -> None:
+        self._intentional_disconnect = False
+
         status = self.query_one("#status", StatusBar)
+        status.reconnecting = False
         status.connected = True
         srv = self._config.server
         status.server_info = f"{srv.host}:{srv.port}"
@@ -340,15 +596,24 @@ class TuimbleApp(App):
         self._start_audio()
 
     def on_server_disconnected(self, _msg: ServerDisconnected) -> None:
+        self._audio.stop()
+
         status = self.query_one("#status", StatusBar)
         status.connected = False
         status.server_info = ""
 
+        tree = self.query_one("#sidebar", ChannelTree)
+        tree.clear_state()
+
+        if self._intentional_disconnect or self._reconnecting:
+            return
+
         chatlog = self.query_one("#chatlog", ChatLog)
         chatlog.write("[#f7768e]\u2717 disconnected from server[/]")
 
-        tree = self.query_one("#sidebar", ChannelTree)
+        self._reconnecting = True
-        tree.clear_state()
+        self._reconnect_attempt = 0
+        self._reconnect_loop()
 
     def on_text_message_received(self, msg: TextMessageReceived) -> None:
         chatlog = self.query_one("#chatlog", ChatLog)
@@ -357,7 +622,24 @@ class TuimbleApp(App):
         chatlog.write(f"[#7aa2f7]{msg.sender}[/] {clean}")
 
     def on_server_state_changed(self, _msg: ServerStateChanged) -> None:
-        self._refresh_channel_tree()
+        if self._tree_refresh_timer is not None:
+            self._tree_refresh_timer.stop()
+        self._tree_refresh_timer = self.set_timer(
+            TREE_DEBOUNCE, self._refresh_channel_tree,
+        )
+
+    def on_channel_selected(self, msg: ChannelSelected) -> None:
+        if not self._client.connected:
+            return
+        ch = self._client.channels.get(msg.channel_id)
+        name = ch.name if ch else str(msg.channel_id)
+        try:
+            self._client.join_channel(msg.channel_id)
+        except Exception as exc:
+            self._show_error(f"join failed: {exc}")
+            return
+        chatlog = self.query_one("#chatlog", ChatLog)
+        chatlog.write(f"[dim]\u2192 joined {name}[/dim]")
 
     @on(Input.Submitted, "#input")
     def on_input_submitted(self, event: Input.Submitted) -> None:
@@ -408,13 +690,13 @@ class TuimbleApp(App):
             return
         channels = self._client.channels
         users = self._client.users
-        users_by_channel: dict[int, list[str]] = {}
+        users_by_channel: dict[int, list[User]] = {}
         for u in users.values():
-            users_by_channel.setdefault(u.channel_id, []).append(u.name)
+            users_by_channel.setdefault(u.channel_id, []).append(u)
         for lst in users_by_channel.values():
-            lst.sort()
+            lst.sort(key=lambda u: u.name)
         tree = self.query_one("#sidebar", ChannelTree)
-        tree.set_state(channels, users_by_channel)
+        tree.set_state(channels, users_by_channel, self._client.my_channel_id)
 
     # -- deafen --------------------------------------------------------------
 
@@ -431,10 +713,217 @@ class TuimbleApp(App):
         else:
             chatlog.write("[#9ece6a]\u2713 undeafened[/]")
 
+    # -- volume ---------------------------------------------------------------
+
+    def action_cycle_output_volume(self) -> None:
+        """Cycle output volume through preset steps."""
+        vol = _next_volume(self._audio.output_gain)
+        self._audio.output_gain = vol
+        pct = int(vol * 100)
+        status = self.query_one("#status", StatusBar)
+        status.output_vol = pct
+        chatlog = self.query_one("#chatlog", ChatLog)
+        chatlog.write(f"[dim]output volume {pct}%[/dim]")
+
+    def action_cycle_input_volume(self) -> None:
+        """Cycle input volume through preset steps."""
+        vol = _next_volume(self._audio.input_gain)
+        self._audio.input_gain = vol
+        pct = int(vol * 100)
+        status = self.query_one("#status", StatusBar)
+        status.input_vol = pct
+        chatlog = self.query_one("#chatlog", ChatLog)
+        chatlog.write(f"[dim]input volume {pct}%[/dim]")
+
+    # -- config reload --------------------------------------------------------
+
+    def _detect_config_changes(
+        self, old: Config, new: Config,
+    ) -> tuple[list[str], list[str]]:
+        """Compare configs, return (safe_changes, restart_changes)."""
+        safe: list[str] = []
+        restart: list[str] = []
+
+        if old.ptt.key != new.ptt.key:
+            safe.append(f"ptt key: {old.ptt.key} -> {new.ptt.key}")
+        if old.ptt.mode != new.ptt.mode:
+            safe.append(f"ptt mode: {old.ptt.mode} -> {new.ptt.mode}")
+        if old.ptt.backend != new.ptt.backend:
+            safe.append(
+                f"ptt backend: {old.ptt.backend} -> {new.ptt.backend}"
+            )
+        if old.audio.input_gain != new.audio.input_gain:
+            safe.append(
+                f"input gain: {old.audio.input_gain} -> "
+                f"{new.audio.input_gain}"
+            )
+        if old.audio.output_gain != new.audio.output_gain:
+            safe.append(
+                f"output gain: {old.audio.output_gain} -> "
+                f"{new.audio.output_gain}"
+            )
+
+        o_srv, n_srv = old.server, new.server
+        for attr in ("host", "port", "username", "password",
+                      "certfile", "keyfile"):
+            ov, nv = getattr(o_srv, attr), getattr(n_srv, attr)
+            if ov != nv:
+                label = "password" if attr == "password" else attr
+                restart.append(f"server.{label} changed")
+
+        o_aud, n_aud = old.audio, new.audio
+        for attr in ("input_device", "output_device", "sample_rate"):
+            ov, nv = getattr(o_aud, attr), getattr(n_aud, attr)
+            if ov != nv:
+                restart.append(f"audio.{attr} changed")
+
+        return safe, restart
+
+    def _apply_safe_changes(self, new: Config) -> None:
+        """Apply hot-reload-safe config changes immediately."""
+        self._config.ptt = new.ptt
+        self._ptt = detect_backend(
+            self._on_ptt_change, new.ptt.backend
+        )
+
+        self._audio.input_gain = new.audio.input_gain
+        self._audio.output_gain = new.audio.output_gain
+        status = self.query_one("#status", StatusBar)
+        status.input_vol = int(new.audio.input_gain * 100)
+        status.output_vol = int(new.audio.output_gain * 100)
+
+    def _apply_restart_changes(self, new: Config) -> None:
+        """Apply changes that require reconnect/audio restart."""
+        chatlog = self.query_one("#chatlog", ChatLog)
+        old = self._config
+
+        server_changed = (
+            old.server.host != new.server.host
+            or old.server.port != new.server.port
+            or old.server.username != new.server.username
+            or old.server.password != new.server.password
+            or old.server.certfile != new.server.certfile
+            or old.server.keyfile != new.server.keyfile
+        )
+        audio_hw_changed = (
+            old.audio.input_device != new.audio.input_device
+            or old.audio.output_device != new.audio.output_device
+            or old.audio.sample_rate != new.audio.sample_rate
+        )
+
+        if server_changed:
+            self._intentional_disconnect = True
+            self._cancel_reconnect()
+            self._audio.stop()
+            self._client.set_dispatcher(None)
+            self._client.disconnect()
+            tree = self.query_one("#sidebar", ChannelTree)
+            tree.clear_state()
+
+            srv = new.server
+            self._client = MumbleClient(
+                host=srv.host,
+                port=srv.port,
+                username=srv.username,
+                password=srv.password,
+                certfile=srv.certfile,
+                keyfile=srv.keyfile,
+            )
+            self._config = new
+            chatlog.write(
+                f"[dim]reconnecting to {srv.host}:{srv.port}...[/]"
+            )
+            self._connect_to_server()
+        elif audio_hw_changed:
+            self._audio.stop()
+            acfg = new.audio
+            self._audio = AudioPipeline(
+                sample_rate=acfg.sample_rate,
+                frame_size=acfg.frame_size,
+                input_device=acfg.input_device,
+                output_device=acfg.output_device,
+            )
+            self._audio.input_gain = acfg.input_gain
+            self._audio.output_gain = acfg.output_gain
+            self._config = new
+            if self._client.connected:
+                self._start_audio()
+            chatlog.write("[dim]audio pipeline restarted[/dim]")
+
+    def action_reload_config(self) -> None:
+        """Reload config from disk (F5).
+
+        Also serves as manual reconnect when disconnected.
+        """
+        if self._reconnecting:
+            self._cancel_reconnect()
+
+        if not self._client.connected:
+            chatlog = self.query_one("#chatlog", ChatLog)
+            srv = self._config.server
+            self._client = MumbleClient(
+                host=srv.host,
+                port=srv.port,
+                username=srv.username,
+                password=srv.password,
+                certfile=srv.certfile,
+                keyfile=srv.keyfile,
+            )
+            chatlog.write(
+                f"[dim]connecting to {srv.host}:{srv.port}...[/dim]"
+            )
+            self._intentional_disconnect = False
+            self._connect_to_server()
+            return
+
+        chatlog = self.query_one("#chatlog", ChatLog)
+
+        if self._pending_reload is not None:
+            new = self._pending_reload
+            self._pending_reload = None
+            self._apply_restart_changes(new)
+            return
+
+        try:
+            new = load_config()
+        except Exception as exc:
+            self._show_error(f"config reload: {exc}")
+            return
+
+        safe, restart = self._detect_config_changes(self._config, new)
+
+        if not safe and not restart:
+            chatlog.write("[dim]config unchanged[/dim]")
+            return
+
+        self._apply_safe_changes(new)
+        self._config.audio.input_gain = new.audio.input_gain
+        self._config.audio.output_gain = new.audio.output_gain
+
+        if safe:
+            for change in safe:
+                chatlog.write(f"[dim]\u2713 {change}[/dim]")
+
+        if restart:
+            for change in restart:
+                chatlog.write(f"[#e0af68]\u26a0 {change}[/]")
+            chatlog.write(
+                "[dim]press F5 again to apply, "
+                "or any key to cancel[/dim]"
+            )
+            self._pending_reload = new
+        else:
+            chatlog.write("[dim]\u2713 config reloaded[/dim]")
+
     # -- PTT -----------------------------------------------------------------
 
     def on_key(self, event: events.Key) -> None:
         """Handle input history navigation and PTT key events."""
+        if self._pending_reload is not None and event.key != "f5":
+            self._pending_reload = None
+            chatlog = self.query_one("#chatlog", ChatLog)
+            chatlog.write("[dim]reload cancelled[/dim]")
+
         focused = self.focused
         if isinstance(focused, Input) and event.key in ("up", "down"):
             inp = focused
@@ -494,6 +983,8 @@ class TuimbleApp(App):
     # -- lifecycle -----------------------------------------------------------
 
     def action_quit(self) -> None:
+        self._intentional_disconnect = True
+        self._cancel_reconnect()
         self._audio.stop()
         self._client.set_dispatcher(None)
         self._client.disconnect()

src/tuimble/audio.py

@@ -9,6 +9,7 @@ from __future__ import annotations
 
 import logging
 import queue
+import struct
 
 log = logging.getLogger(__name__)
 
@@ -18,6 +19,17 @@ FRAME_SIZE = 960  # 20ms at 48kHz
 DTYPE = "int16"
 
 
+def _apply_gain(pcm: bytes, gain: float) -> bytes:
+    """Scale int16 PCM samples by gain factor with clipping."""
+    n = len(pcm) // 2
+    if n == 0:
+        return pcm
+    fmt = f"<{n}h"
+    samples = struct.unpack(fmt, pcm[: n * 2])
+    scaled = [max(-32768, min(32767, int(s * gain))) for s in samples]
+    return struct.pack(fmt, *scaled)
+
+
 class AudioPipeline:
     """Manages audio input/output streams and Opus codec."""
 
@@ -40,6 +52,8 @@ class AudioPipeline:
         self._output_stream = None
         self._capturing = False
         self._deafened = False
+        self._input_gain = 1.0
+        self._output_gain = 1.0
 
     def start(self):
         """Open audio streams."""
@@ -93,13 +107,32 @@ class AudioPipeline:
     def deafened(self, value: bool):
         self._deafened = value
 
+    @property
+    def input_gain(self) -> float:
+        return self._input_gain
+
+    @input_gain.setter
+    def input_gain(self, value: float):
+        self._input_gain = max(0.0, min(2.0, value))
+
+    @property
+    def output_gain(self) -> float:
+        return self._output_gain
+
+    @output_gain.setter
+    def output_gain(self, value: float):
+        self._output_gain = max(0.0, min(2.0, value))
+
     def _capture_callback(self, indata, frames, time_info, status):
         """Called by sounddevice when input data is available."""
         if status:
             log.warning("capture status: %s", status)
         if self._capturing:
             try:
-                self._capture_queue.put_nowait(bytes(indata))
+                pcm = bytes(indata)
+                if self._input_gain != 1.0:
+                    pcm = _apply_gain(pcm, self._input_gain)
+                self._capture_queue.put_nowait(pcm)
             except queue.Full:
                 pass
 
@@ -112,6 +145,8 @@ class AudioPipeline:
             return
         try:
             pcm = self._playback_queue.get_nowait()
+            if self._output_gain != 1.0:
+                pcm = _apply_gain(pcm, self._output_gain)
             n = min(len(pcm), len(outdata))
             outdata[:n] = pcm[:n]
             if n < len(outdata):

src/tuimble/client.py

@@ -9,12 +9,26 @@ event loop (e.g. Textual's call_from_thread).
 from __future__ import annotations
 
 import logging
+import socket
 from dataclasses import dataclass
 from typing import Callable
 
 log = logging.getLogger(__name__)
 
 
+class ConnectionFailed(Exception):
+    """Connection attempt failed.
+
+    Attributes:
+        retryable: Whether the caller should attempt reconnection.
+            False for authentication rejections, True for network errors.
+    """
+
+    def __init__(self, message: str, *, retryable: bool = True):
+        super().__init__(message)
+        self.retryable = retryable
+
+
 @dataclass
 class User:
     session_id: int
@@ -48,11 +62,15 @@ class MumbleClient:
         port: int = 64738,
         username: str = "tuimble-user",
         password: str = "",
+        certfile: str = "",
+        keyfile: str = "",
     ):
         self._host = host
         self._port = port
         self._username = username
         self._password = password
+        self._certfile = certfile
+        self._keyfile = keyfile
         self._mumble = None
         self._connected = False
         self._dispatcher: Callable | None = None
@@ -134,15 +152,30 @@ class MumbleClient:
     # -- connection ----------------------------------------------------------
 
     def connect(self):
-        """Connect to the Mumble server (blocking)."""
+        """Connect to the Mumble server (blocking).
-        import pymumble_py3 as pymumble
 
+        Raises:
+            ConnectionFailed: On any connection failure.  Check the
+                ``retryable`` attribute to decide whether to retry.
+        """
+        import pymumble_py3 as pymumble
+        import pymumble_py3.constants as const
+
+        kwargs = {
+            "port": self._port,
+            "password": self._password,
+            "reconnect": False,
+        }
+        if self._certfile:
+            kwargs["certfile"] = self._certfile
+        if self._keyfile:
+            kwargs["keyfile"] = self._keyfile
+
+        try:
             self._mumble = pymumble.Mumble(
                 self._host,
                 self._username,
-            port=self._port,
+                **kwargs,
-            password=self._password,
-            reconnect=False,
             )
             self._mumble.set_codec_profile("audio")
             self._mumble.set_receive_sound(True)
@@ -150,8 +183,26 @@ class MumbleClient:
 
             self._mumble.start()
             self._mumble.is_ready()  # blocks until handshake completes
+        except (socket.error, OSError) as exc:
+            self._connected = False
+            raise ConnectionFailed(
+                f"network error: {exc}", retryable=True,
+            ) from exc
+        except Exception as exc:
+            self._connected = False
+            raise ConnectionFailed(str(exc), retryable=True) from exc
+
+        if self._mumble.connected != const.PYMUMBLE_CONN_STATE_CONNECTED:
+            self._connected = False
+            raise ConnectionFailed(
+                "server rejected connection", retryable=False,
+            )
+
         self._connected = True
-        log.info("connected to %s:%d as %s", self._host, self._port, self._username)
+        log.info(
+            "connected to %s:%d as %s",
+            self._host, self._port, self._username,
+        )
 
     def disconnect(self):
         """Disconnect from the server."""
@@ -163,6 +214,16 @@ class MumbleClient:
             self._connected = False
             log.info("disconnected")
 
+    def reconnect(self):
+        """Disconnect and reconnect to the same server.
+
+        Raises:
+            ConnectionFailed: On connection failure (see ``connect``).
+        """
+        self.disconnect()
+        self._mumble = None
+        self.connect()
+
     # -- actions -------------------------------------------------------------
 
     def send_text(self, message: str):

src/tuimble/config.py

@@ -16,6 +16,8 @@ class ServerConfig:
     username: str = "tuimble-user"
     password: str = ""
     channel: str = ""
+    certfile: str = ""
+    keyfile: str = ""
 
 
 @dataclass
@@ -24,6 +26,8 @@ class AudioConfig:
     output_device: int | None = None
     sample_rate: int = 48000
     frame_size: int = 960  # 20ms at 48kHz
+    input_gain: float = 1.0
+    output_gain: float = 1.0
 
 
 @dataclass

tests/test_audio.py

@@ -1,6 +1,8 @@
 """Tests for AudioPipeline."""
 
-from tuimble.audio import FRAME_SIZE, SAMPLE_RATE, AudioPipeline
+import struct
+
+from tuimble.audio import FRAME_SIZE, SAMPLE_RATE, AudioPipeline, _apply_gain
 
 
 def test_default_construction():
@@ -125,3 +127,79 @@ def test_stop_without_start():
     """Stop on unstarted pipeline should not raise."""
     ap = AudioPipeline()
     ap.stop()
+
+
+# -- _apply_gain tests -------------------------------------------------------
+
+
+def test_apply_gain_unity():
+    """Gain 1.0 returns identical samples."""
+    pcm = struct.pack("<4h", 100, -200, 32767, -32768)
+    assert _apply_gain(pcm, 1.0) == pcm
+
+
+def test_apply_gain_double():
+    """Gain 2.0 doubles sample values."""
+    pcm = struct.pack("<2h", 100, -100)
+    result = struct.unpack("<2h", _apply_gain(pcm, 2.0))
+    assert result == (200, -200)
+
+
+def test_apply_gain_clips():
+    """Values exceeding int16 range are clipped."""
+    pcm = struct.pack("<2h", 20000, -20000)
+    result = struct.unpack("<2h", _apply_gain(pcm, 2.0))
+    assert result == (32767, -32768)
+
+
+def test_apply_gain_zero():
+    """Gain 0.0 produces silence."""
+    pcm = struct.pack("<2h", 1000, -1000)
+    result = struct.unpack("<2h", _apply_gain(pcm, 0.0))
+    assert result == (0, 0)
+
+
+def test_apply_gain_empty():
+    """Empty buffer returns empty."""
+    assert _apply_gain(b"", 2.0) == b""
+
+
+# -- gain property tests ------------------------------------------------------
+
+
+def test_gain_defaults():
+    ap = AudioPipeline()
+    assert ap.input_gain == 1.0
+    assert ap.output_gain == 1.0
+
+
+def test_gain_clamping():
+    ap = AudioPipeline()
+    ap.input_gain = 3.0
+    assert ap.input_gain == 2.0
+    ap.output_gain = -1.0
+    assert ap.output_gain == 0.0
+
+
+def test_capture_callback_applies_input_gain():
+    """Input gain is applied to captured PCM."""
+    ap = AudioPipeline()
+    ap.capturing = True
+    ap.input_gain = 0.5
+    pcm = struct.pack("<2h", 1000, -1000)
+    ap._capture_callback(pcm, 2, None, None)
+    frame = ap.get_capture_frame()
+    result = struct.unpack("<2h", frame)
+    assert result == (500, -500)
+
+
+def test_playback_callback_applies_output_gain():
+    """Output gain is applied during playback."""
+    ap = AudioPipeline()
+    ap.output_gain = 0.5
+    pcm = struct.pack("<2h", 1000, -1000)
+    ap.queue_playback(pcm)
+    outdata = bytearray(4)
+    ap._playback_callback(outdata, 2, None, None)
+    result = struct.unpack("<2h", bytes(outdata))
+    assert result == (500, -500)

tests/test_client.py

@@ -1,8 +1,8 @@
 """Tests for MumbleClient dispatcher and callback wiring."""
 
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
-from tuimble.client import MumbleClient
+from tuimble.client import ConnectionFailed, MumbleClient
 
 
 def test_default_state():
@@ -67,3 +67,56 @@ def test_set_self_deaf_noop_when_disconnected():
     client = MumbleClient(host="localhost")
     # Should not raise when not connected
     client.set_self_deaf(True)
+
+
+def test_cert_defaults():
+    client = MumbleClient(host="localhost")
+    assert client._certfile == ""
+    assert client._keyfile == ""
+
+
+def test_cert_custom():
+    client = MumbleClient(
+        host="localhost",
+        certfile="/path/cert.pem",
+        keyfile="/path/key.pem",
+    )
+    assert client._certfile == "/path/cert.pem"
+    assert client._keyfile == "/path/key.pem"
+
+
+def test_connection_failed_retryable():
+    exc = ConnectionFailed("network error", retryable=True)
+    assert str(exc) == "network error"
+    assert exc.retryable is True
+
+
+def test_connection_failed_not_retryable():
+    exc = ConnectionFailed("auth rejected", retryable=False)
+    assert str(exc) == "auth rejected"
+    assert exc.retryable is False
+
+
+def test_connection_failed_default_retryable():
+    exc = ConnectionFailed("something broke")
+    assert exc.retryable is True
+
+
+def test_reconnect_resets_state():
+    client = MumbleClient(host="localhost")
+    client._connected = True
+    client._mumble = MagicMock()
+
+    with patch.object(client, "connect"):
+        client.reconnect()
+
+    # disconnect should have cleared _mumble before connect
+    assert client._connected is False
+
+
+def test_disconnect_clears_connected():
+    client = MumbleClient(host="localhost")
+    client._connected = True
+    client._mumble = MagicMock()
+    client.disconnect()
+    assert client.connected is False

tests/test_config.py

@@ -1,6 +1,6 @@
 """Tests for configuration module."""
 
-from tuimble.config import Config, PttConfig, ServerConfig
+from tuimble.config import AudioConfig, Config, PttConfig, ServerConfig
 
 
 def test_default_config():
@@ -21,3 +21,27 @@ def test_ptt_config_defaults():
     ptt = PttConfig()
     assert ptt.key == "f4"
     assert ptt.backend == "auto"
+
+
+def test_audio_gain_defaults():
+    acfg = AudioConfig()
+    assert acfg.input_gain == 1.0
+    assert acfg.output_gain == 1.0
+
+
+def test_audio_gain_custom():
+    acfg = AudioConfig(input_gain=0.5, output_gain=1.5)
+    assert acfg.input_gain == 0.5
+    assert acfg.output_gain == 1.5
+
+
+def test_server_cert_defaults():
+    srv = ServerConfig()
+    assert srv.certfile == ""
+    assert srv.keyfile == ""
+
+
+def test_server_cert_custom():
+    srv = ServerConfig(certfile="/path/cert.pem", keyfile="/path/key.pem")
+    assert srv.certfile == "/path/cert.pem"
+    assert srv.keyfile == "/path/key.pem"