diff --git a/AGENTS.md b/AGENTS.md
index 5309b15..45e3c0a 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -49,23 +49,29 @@ The project operates entirely from the app directory without depending on `~/Wor
 - **CLI Helper Scripts**:
   - `bin/voice_tool.py`: List and switch TTS voices (`python bin/voice_tool.py list`, `python bin/voice_tool.py set <voice>`).
   - `bin/model_tool.py`: List and switch LLM models (`python bin/model_tool.py list`, `python bin/model_tool.py set <model>`).
+  - `bin/session_tool.py`: Inspect or reset active Hermes session (`python bin/session_tool.py get`, `python bin/session_tool.py reset`).
+  - `bin/profile_tool.py`: List and switch Hermes agent profiles (`python bin/profile_tool.py list`, `python bin/profile_tool.py set <profile>`).
   - `bin/web_tool.py`: Inspect files or URLs in the Companion Web UI drawer (`http://localhost:8888`).
 
 ---
 
 ## 4. Building & Packaging `/Applications/VoiceAgent.app`
 
-Whenever python or Swift sources are modified, update the standalone macOS application bundle:
+`VoiceAgentLauncher` runs Python scripts dynamically from the project workspace (configured in `~/.voiceagent.env` or `VOICEAGENT_DIR`). 
+
+- **Python code edits take effect immediately** without recompiling or re-signing the macOS app bundle.
+- **Rebuilding binaries** (`bash build_app.sh`) is only required when modifying Swift sources (`swift/*.swift`), helper binaries, or `Info.plist` entitlements.
+- `build_app.sh` automatically updates `~/.voiceagent.env` and skips binary re-signing if Swift sources are unchanged, preserving macOS privacy permissions (Microphone, Accessibility, Speech Recognition). Use `bash build_app.sh -f` to force a full rebuild.
 
 ```bash
 bash build_app.sh
 ```
 
 **Build Workflow**:
-1. Builds Swift binaries (`swift/build.sh` -> `speech-helper`, `llm-helper`, `VoiceAgentLauncher`).
-2. Bundles Python source files, `bin/` tools, and assets into `dist/VoiceAgent.app`.
-3. Signs the app bundle (`codesign -s - --deep --force`).
-4. Replaces `/Applications/VoiceAgent.app`.
+1. Configures `~/.voiceagent.env` with `VOICEAGENT_DIR` and `VOICEAGENT_PYTHON`.
+2. Checks if Swift binaries (`speech-helper`, `llm-helper`, `VoiceAgentLauncher`) need recompiling.
+3. If up to date, copies Python resources without re-signing the app bundle (preserving macOS TCC permissions).
+4. If modified, compiles Swift binaries, creates `dist/VoiceAgent.app`, signs, and installs to `/Applications/VoiceAgent.app`.
 
 ---
 
@@ -74,6 +80,8 @@ bash build_app.sh
 Before committing changes, execute the test suite:
 
 ```bash
+.venv/bin/python3 test_profile_tool.py
+.venv/bin/python3 test_session_tool.py
 .venv/bin/python3 test_model_manager.py
 .venv/bin/python3 test_spoken_text.py
 .venv/bin/python3 test_journal.py
diff --git a/README.md b/README.md
index dfe0434..777c42d 100644
--- a/README.md
+++ b/README.md
@@ -70,6 +70,41 @@ terminal under System Settings → Privacy & Security → Microphone.
 
 The speech model downloads itself the first time a locale is used.
 
+## macOS AirPods route switching checklist
+
+When no audio device is pinned, VoiceAgent follows macOS's current default
+microphone and speaker while a conversation is running. Use this checklist when
+validating AirPods or another Bluetooth headset:
+
+1. Connect AirPods before starting `./talk`; confirm that both microphone and
+   speaker audio use them.
+2. Start a conversation on the built-in microphone and speakers, then connect
+   AirPods. Confirm that each available direction moves independently to the
+   new macOS default without ending the conversation.
+3. Disconnect AirPods during a conversation. Confirm that the available input
+   and output return to the macOS defaults and that the conversation remains
+   usable.
+4. In Control Center or Sound settings, explicitly switch back to the built-in
+   microphone and speakers while AirPods remain connected. Confirm both routes
+   follow those defaults.
+5. Repeat connect, disconnect, and manual default changes several times to
+   catch delayed Bluetooth profile changes or a stale route listener.
+
+Run this validation without `--input-device` or `--output-device`: omitted
+values intentionally follow macOS defaults. Supplying either flag pins only that
+direction (for example, a pinned USB microphone still allows an unpinned output
+to follow AirPods); pinning both directions disables automatic route following.
+Use `./talk --list-devices` to identify a device by index or name substring.
+
+This behavior depends on macOS Core Audio notifications and the device profile
+currently exposed by Bluetooth. A headset may briefly expose only output, or
+reject the negotiated sample rate while switching profiles; VoiceAgent keeps the
+previous working route when a replacement cannot open. The terminal/app still
+needs macOS Microphone permission, and the global hold-key needs Input
+Monitoring. A sandboxed packaged app also needs the appropriate microphone usage
+description and audio-input entitlement; those platform permissions cannot be
+granted by route switching code.
+
 ## Turn taking, and why it's push-to-talk
 
 Detecting the end of a turn by listening for silence is both slow and wrong
diff --git a/audio_device_monitor.py b/audio_device_monitor.py
new file mode 100644
index 0000000..81f633d
--- /dev/null
+++ b/audio_device_monitor.py
@@ -0,0 +1,357 @@
+"""macOS default audio-device monitoring.
+
+The monitor deliberately depends on a small backend protocol.  Core Audio invokes
+listeners on an arbitrary thread, while VoiceAgent consumes snapshots on its
+asyncio loop; :class:`AudioDeviceMonitor` is the lifecycle and thread boundary
+between those two worlds.  The backend can be replaced by a deterministic fake
+in unit tests.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import ctypes
+import ctypes.util
+import inspect
+import sys
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import Callable, Protocol
+
+
+class DeviceChangeReason(str, Enum):
+    INITIAL = "initial"
+    DEFAULT_CHANGED = "default_changed"
+    DEVICE_ADDED = "device_added"
+    DEVICE_REMOVED = "device_removed"
+    DEVICE_RECONFIGURED = "device_reconfigured"
+    PROFILE_CHANGED = "profile_changed"
+
+
+@dataclass(frozen=True)
+class AudioDevice:
+    uid: str
+    name: str
+    can_input: bool
+    can_output: bool
+    transport: str = "unknown"
+    alive: bool = True
+
+
+@dataclass(frozen=True)
+class AudioDeviceSnapshot:
+    generation: int
+    default_input_uid: str | None
+    default_output_uid: str | None
+    devices: dict[str, AudioDevice] = field(default_factory=dict)
+    reason: DeviceChangeReason = DeviceChangeReason.INITIAL
+
+
+Listener = Callable[[], None]
+
+
+class AudioDeviceBackend(Protocol):
+    """The minimal Core Audio surface required by the monitor."""
+
+    def enumerate_devices(self) -> list[AudioDevice]: ...
+    def default_input_uid(self) -> str | None: ...
+    def default_output_uid(self) -> str | None: ...
+    def add_listener(self, callback: Listener) -> object: ...
+    def remove_listener(self, token: object) -> None: ...
+
+
+class AudioDeviceMonitor:
+    """Coalesces Core Audio notifications and dispatches snapshots on one loop."""
+
+    def __init__(self, backend: AudioDeviceBackend, *, debounce_seconds: float = 0.05,
+                 loop: asyncio.AbstractEventLoop | None = None):
+        self._backend = backend
+        self._debounce_seconds = debounce_seconds
+        self._loop = loop
+        self._callback: Callable[[AudioDeviceSnapshot], object] | None = None
+        self._snapshot = AudioDeviceSnapshot(0, None, None)
+        self._generation = 0
+        self._listener_tokens: list[object] = []
+        self._debounce_handle: asyncio.TimerHandle | None = None
+        self._running = False
+        self._refresh_scheduled = False
+        self._refresh_task: asyncio.Task[None] | None = None
+
+    async def start(self, on_change: Callable[[AudioDeviceSnapshot], object]) -> None:
+        """Register listeners once and publish an initial snapshot.
+
+        ``on_change`` may be synchronous or return an awaitable.  It is always
+        called on the loop used by this monitor, never on a Core Audio thread.
+        """
+        if self._running:
+            return
+        self._loop = self._loop or asyncio.get_running_loop()
+        self._callback = on_change
+        self._running = True
+        try:
+            # Register all listeners before the initial read so a concurrent
+            # device change cannot be missed.
+            self._listener_tokens = [self._backend.add_listener(self._on_backend_event) for _ in range(1)]
+            await self._refresh(DeviceChangeReason.INITIAL)
+        except Exception:
+            await self.stop()
+            raise
+
+    async def stop(self) -> None:
+        """Stop idempotently and ensure no callback can be scheduled afterward."""
+        self._running = False
+        if self._debounce_handle:
+            self._debounce_handle.cancel()
+            self._debounce_handle = None
+        current_task = asyncio.current_task()
+        if (self._refresh_task and not self._refresh_task.done()
+                and self._refresh_task is not current_task):
+            self._refresh_task.cancel()
+            try:
+                await self._refresh_task
+            except asyncio.CancelledError:
+                pass
+        self._refresh_task = None
+        tokens, self._listener_tokens = self._listener_tokens, []
+        for token in tokens:
+            self._backend.remove_listener(token)
+        self._callback = None
+        self._refresh_scheduled = False
+
+    def snapshot(self) -> AudioDeviceSnapshot:
+        return self._snapshot
+
+    def _on_backend_event(self) -> None:
+        """Core Audio callback entry point; safe to call from any thread."""
+        if not self._running or not self._loop:
+            return
+        self._loop.call_soon_threadsafe(self._schedule_refresh)
+
+    def _schedule_refresh(self) -> None:
+        if not self._running or self._refresh_scheduled:
+            return
+        self._refresh_scheduled = True
+        if self._debounce_handle:
+            self._debounce_handle.cancel()
+        self._debounce_handle = self._loop.call_later(self._debounce_seconds, self._start_refresh)
+
+    def _start_refresh(self) -> None:
+        self._debounce_handle = None
+        self._refresh_scheduled = False
+        if self._running:
+            self._refresh_task = self._loop.create_task(self._refresh(self._infer_reason()))
+            self._refresh_task.add_done_callback(self._consume_refresh_failure)
+
+    @staticmethod
+    def _consume_refresh_failure(task: asyncio.Task[None]) -> None:
+        """Retrieve scheduled refresh failures after cleanup has completed."""
+        if not task.cancelled():
+            task.exception()
+
+    def _infer_reason(self) -> DeviceChangeReason:
+        # The backend intentionally keeps the callback payload-free.  The
+        # resulting snapshot is authoritative; callers can inspect UID/device
+        # differences.  A generic device reconfiguration is safest here.
+        return DeviceChangeReason.DEFAULT_CHANGED
+
+    async def _refresh(self, reason: DeviceChangeReason) -> None:
+        if not self._running:
+            return
+        devices = {d.uid: d for d in self._backend.enumerate_devices() if d.uid and d.alive}
+        new_input = self._backend.default_input_uid()
+        new_output = self._backend.default_output_uid()
+        # An unavailable default is represented as None rather than a stale UID.
+        if new_input not in devices or not devices[new_input].can_input:
+            new_input = None
+        if new_output not in devices or not devices[new_output].can_output:
+            new_output = None
+        old = self._snapshot
+        if (old.default_input_uid == new_input and old.default_output_uid == new_output
+                and old.devices == devices and old.generation != 0):
+            return
+        if old.generation and reason != DeviceChangeReason.INITIAL:
+            old_uids, new_uids = set(old.devices), set(devices)
+            if old.default_input_uid != new_input or old.default_output_uid != new_output:
+                reason = DeviceChangeReason.DEFAULT_CHANGED
+            elif new_uids - old_uids:
+                reason = DeviceChangeReason.DEVICE_ADDED
+            elif old_uids - new_uids:
+                reason = DeviceChangeReason.DEVICE_REMOVED
+            elif any(old.devices[uid] != device for uid, device in devices.items()
+                     if uid in old.devices):
+                reason = DeviceChangeReason.PROFILE_CHANGED
+        self._generation += 1
+        self._snapshot = AudioDeviceSnapshot(self._generation, new_input, new_output, devices, reason)
+        callback = self._callback
+        if callback and self._running:
+            try:
+                result = callback(self._snapshot)
+                if inspect.isawaitable(result):
+                    await result
+            except Exception:
+                # A failed consumer must not leave a native listener active with
+                # an unusable callback.  ``stop`` handles the current refresh
+                # task specially so this cleanup is safe from inside _refresh.
+                await self.stop()
+                raise
+
+
+class MacOSCoreAudioBackend:
+    """Core Audio backend hook.
+
+    PyObjC's CoreAudio listener ABI differs between macOS releases.  Keeping the
+    native adapter behind this class lets packaging provide the matching adapter
+    without exposing it to the async monitor or its tests.
+    """
+
+    def __init__(self, adapter):
+        self._adapter = adapter
+
+    def enumerate_devices(self) -> list[AudioDevice]:
+        return list(self._adapter.enumerate_devices())
+
+    def default_input_uid(self) -> str | None:
+        return self._adapter.default_input_uid()
+
+    def default_output_uid(self) -> str | None:
+        return self._adapter.default_output_uid()
+
+    def add_listener(self, callback: Listener) -> object:
+        return self._adapter.add_device_listener(callback)
+
+    def remove_listener(self, token: object) -> None:
+        self._adapter.remove_device_listener(token)
+
+
+class NativeMacOSCoreAudioAdapter:
+    """Native Core Audio adapter using stable device UIDs, never PortAudio IDs."""
+
+    _SYSTEM_OBJECT = 1
+    _GLOBAL = int.from_bytes(b"glob", "big")
+    _INPUT_SCOPE = int.from_bytes(b"inpt", "big")
+    _OUTPUT_SCOPE = int.from_bytes(b"outp", "big")
+    _DEFAULT_INPUT = int.from_bytes(b"dIn ", "big")
+    _DEFAULT_OUTPUT = int.from_bytes(b"dOut", "big")
+    _DEVICES = int.from_bytes(b"dev#", "big")
+    _UID = int.from_bytes(b"uid ", "big")
+    _NAME = int.from_bytes(b"lnam", "big")
+    _ALIVE = int.from_bytes(b"livn", "big")
+    _TRANSPORT = int.from_bytes(b"tran", "big")
+    _STREAMS = int.from_bytes(b"stm#", "big")
+
+    class _Address(ctypes.Structure):
+        _fields_ = [("selector", ctypes.c_uint32), ("scope", ctypes.c_uint32), ("element", ctypes.c_uint32)]
+
+    def __init__(self):
+        if sys.platform != "darwin":
+            raise RuntimeError("Core Audio is only available on macOS")
+        core_audio = ctypes.util.find_library("CoreAudio")
+        core_foundation = ctypes.util.find_library("CoreFoundation")
+        if not core_audio or not core_foundation:
+            raise RuntimeError("CoreAudio.framework is unavailable")
+        self._lib = ctypes.CDLL(core_audio)
+        self._cf = ctypes.CDLL(core_foundation)
+        self._listener_type = ctypes.CFUNCTYPE(ctypes.c_int32, ctypes.c_uint32, ctypes.c_uint32,
+                                                ctypes.POINTER(self._Address), ctypes.c_void_p)
+        self._lib.AudioObjectGetPropertyData.argtypes = [ctypes.c_uint32, ctypes.POINTER(self._Address), ctypes.c_uint32, ctypes.c_void_p, ctypes.POINTER(ctypes.c_uint32), ctypes.c_void_p]
+        self._lib.AudioObjectGetPropertyData.restype = ctypes.c_int32
+        self._lib.AudioObjectGetPropertyDataSize.argtypes = [ctypes.c_uint32, ctypes.POINTER(self._Address), ctypes.c_uint32, ctypes.c_void_p, ctypes.POINTER(ctypes.c_uint32)]
+        self._lib.AudioObjectGetPropertyDataSize.restype = ctypes.c_int32
+        self._lib.AudioObjectAddPropertyListener.argtypes = [ctypes.c_uint32, ctypes.POINTER(self._Address), self._listener_type, ctypes.c_void_p]
+        self._lib.AudioObjectRemovePropertyListener.argtypes = [ctypes.c_uint32, ctypes.POINTER(self._Address), self._listener_type, ctypes.c_void_p]
+        self._cf.CFStringGetCString.argtypes = [ctypes.c_void_p, ctypes.c_char_p, ctypes.c_long, ctypes.c_uint32]
+        self._callbacks = {}
+
+    def _address(self, selector, scope=None):
+        return self._Address(selector, self._GLOBAL if scope is None else scope, 0)
+
+    def _value(self, object_id, selector, value_type, scope=None):
+        value, size = value_type(), ctypes.c_uint32(ctypes.sizeof(value_type))
+        status = self._lib.AudioObjectGetPropertyData(object_id, ctypes.byref(self._address(selector, scope)), 0, None, ctypes.byref(size), ctypes.byref(value))
+        if status:
+            raise OSError(f"AudioObjectGetPropertyData({selector}) failed: {status}")
+        return value.value
+
+    def _string(self, object_id, selector):
+        ref = self._value(object_id, selector, ctypes.c_void_p)
+        if not ref:
+            return ""
+        buffer = ctypes.create_string_buffer(1024)
+        if not self._cf.CFStringGetCString(ref, buffer, len(buffer), 0x08000100):
+            return ""
+        return buffer.value.decode("utf-8", "replace")
+
+    def _device_ids(self):
+        address, size = self._address(self._DEVICES), ctypes.c_uint32()
+        status = self._lib.AudioObjectGetPropertyDataSize(self._SYSTEM_OBJECT, ctypes.byref(address), 0, None, ctypes.byref(size))
+        if status:
+            raise OSError(f"Audio device enumeration failed: {status}")
+        devices = (ctypes.c_uint32 * (size.value // ctypes.sizeof(ctypes.c_uint32)))()
+        status = self._lib.AudioObjectGetPropertyData(self._SYSTEM_OBJECT, ctypes.byref(address), 0, None, ctypes.byref(size), devices)
+        if status:
+            raise OSError(f"Audio device enumeration failed: {status}")
+        return list(devices)
+
+    def _has_streams(self, device_id, scope):
+        address, size = self._address(self._STREAMS, scope), ctypes.c_uint32()
+        status = self._lib.AudioObjectGetPropertyDataSize(device_id, ctypes.byref(address), 0, None, ctypes.byref(size))
+        return not status and bool(size.value)
+
+    def enumerate_devices(self):
+        devices = []
+        for device_id in self._device_ids():
+            try:
+                uid = self._string(device_id, self._UID)
+                if not uid:
+                    continue
+                devices.append(AudioDevice(uid, self._string(device_id, self._NAME) or uid,
+                    self._has_streams(device_id, self._INPUT_SCOPE), self._has_streams(device_id, self._OUTPUT_SCOPE),
+                    self._fourcc(self._value(device_id, self._TRANSPORT, ctypes.c_uint32)), bool(self._value(device_id, self._ALIVE, ctypes.c_uint32))))
+            except OSError:
+                continue
+        return devices
+
+    @staticmethod
+    def _fourcc(value):
+        return value.to_bytes(4, "big").decode("ascii", "replace").strip() or "unknown"
+
+    def default_input_uid(self):
+        return self._uid_for_id(self._value(self._SYSTEM_OBJECT, self._DEFAULT_INPUT, ctypes.c_uint32))
+
+    def default_output_uid(self):
+        return self._uid_for_id(self._value(self._SYSTEM_OBJECT, self._DEFAULT_OUTPUT, ctypes.c_uint32))
+
+    def _uid_for_id(self, device_id):
+        return self._string(device_id, self._UID) if device_id else None
+
+    def add_device_listener(self, callback):
+        addresses = [(self._SYSTEM_OBJECT, self._address(selector)) for selector in (self._DEFAULT_INPUT, self._DEFAULT_OUTPUT, self._DEVICES)]
+        addresses += [(device_id, self._address(selector, scope)) for device_id in self._device_ids() for selector, scope in ((self._ALIVE, None), (self._STREAMS, self._INPUT_SCOPE), (self._STREAMS, self._OUTPUT_SCOPE))]
+        native_callback = self._listener_type(lambda *_: (callback(), 0)[1])
+        registered = []
+        try:
+            for object_id, address in addresses:
+                status = self._lib.AudioObjectAddPropertyListener(object_id, ctypes.byref(address), native_callback, None)
+                if status:
+                    raise OSError(f"AudioObjectAddPropertyListener failed: {status}")
+                registered.append((object_id, address))
+        except Exception:
+            for object_id, address in registered:
+                self._lib.AudioObjectRemovePropertyListener(object_id, ctypes.byref(address), native_callback, None)
+            raise
+        token = (native_callback, registered)
+        self._callbacks[id(token)] = token
+        return token
+
+    def remove_device_listener(self, token):
+        native_callback, addresses = token
+        for object_id, address in addresses:
+            self._lib.AudioObjectRemovePropertyListener(object_id, ctypes.byref(address), native_callback, None)
+        self._callbacks.pop(id(token), None)
+
+
+def create_macos_audio_monitor(*, adapter=None, **kwargs) -> AudioDeviceMonitor:
+    """Create a native Core Audio monitor (or a supplied test adapter)."""
+    if adapter is None:
+        adapter = NativeMacOSCoreAudioAdapter()
+    return AudioDeviceMonitor(MacOSCoreAudioBackend(adapter), **kwargs)
diff --git a/bin/audio_tool.py b/bin/audio_tool.py
new file mode 100644
index 0000000..a754723
--- /dev/null
+++ b/bin/audio_tool.py
@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""Inspect or switch VoiceAgent's live input/output device through its local UI API."""
+
+import argparse
+import json
+import sys
+from urllib.error import HTTPError, URLError
+from urllib.request import Request, urlopen
+
+BASE_URL = "http://127.0.0.1:8888"
+
+
+def request(path, method="GET", payload=None):
+    data = json.dumps(payload).encode() if payload is not None else None
+    req = Request(BASE_URL + path, data=data, method=method)
+    if data is not None:
+        req.add_header("Content-Type", "application/json")
+    try:
+        with urlopen(req, timeout=5) as response:
+            return json.load(response)
+    except HTTPError as exc:
+        try:
+            message = json.load(exc)
+        except Exception:
+            message = {"error": exc.read().decode("utf-8", "replace")}
+        raise RuntimeError(message.get("error", str(exc))) from exc
+    except URLError as exc:
+        raise RuntimeError(f"VoiceAgent is not reachable at {BASE_URL}: {exc.reason}") from exc
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    commands = parser.add_subparsers(dest="command", required=True)
+    commands.add_parser("list", help="List selectable input/output devices.")
+    select = commands.add_parser("set", help="Switch one live route or follow the macOS default.")
+    select.add_argument("direction", choices=("input", "output"))
+    select.add_argument("device", help="Unique device-name substring, PortAudio index, or 'default'.")
+    args = parser.parse_args()
+    try:
+        if args.command == "list":
+            result = request("/api/audio-devices")
+            for device in result["devices"]:
+                kinds = "/".join(kind for kind in ("input" if device["input"] else "", "output" if device["output"] else "") if kind)
+                print(f"[{device['id']}] {device['name']} ({kinds})")
+        else:
+            result = request("/api/audio-device", "POST", {"direction": args.direction, "device": args.device})
+            mode = "following macOS default" if result["following_default"] else f"pinned to [{result['device']}]"
+            print(f"{args.direction} changed to {result['name']} ({mode})")
+        return 0
+    except (KeyError, RuntimeError) as exc:
+        print(f"audio-tool: {exc}", file=sys.stderr)
+        return 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/bin/profile_tool.py b/bin/profile_tool.py
new file mode 100644
index 0000000..f62de5c
--- /dev/null
+++ b/bin/profile_tool.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+"""CLI helper to list, get, and switch Hermes agent profiles for VoiceAgent."""
+
+import os
+import re
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+# Add VoiceAgent1 project root to sys.path
+project_root = Path(__file__).resolve().parent.parent
+if str(project_root) not in sys.path:
+    sys.path.insert(0, str(project_root))
+
+from hermes_llm import find_hermes_cli
+
+
+def _get_hermes_cli() -> str:
+    cli = find_hermes_cli()
+    if not cli:
+        raise RuntimeError("Hermes CLI binary not found in PATH or standard paths")
+    return cli
+
+
+def list_profiles() -> str:
+    cli = _get_hermes_cli()
+    res = subprocess.run([cli, "profile", "list"], capture_output=True, text=True)
+    if res.returncode != 0:
+        return f"Error listing profiles: {res.stderr.strip()}"
+    return res.stdout.strip()
+
+
+def get_current_profile() -> str:
+    cli = _get_hermes_cli()
+    res = subprocess.run([cli, "profile", "list"], capture_output=True, text=True)
+    if res.returncode == 0:
+        for line in res.stdout.splitlines():
+            line_clean = line.strip()
+            if line_clean.startswith("◆") or line_clean.startswith("*"):
+                parts = line_clean.lstrip("◆* ").split()
+                if parts:
+                    return parts[0]
+    return "default"
+
+
+def set_profile(profile_name: str) -> tuple[bool, str]:
+    target = profile_name.strip().lstrip("◆* ")
+    if not target:
+        return False, "No profile name specified."
+
+    cli = _get_hermes_cli()
+    res = subprocess.run([cli, "profile", "use", target], capture_output=True, text=True)
+    if res.returncode == 0:
+        output_msg = res.stdout.strip() or f"Switched to Hermes profile '{target}'."
+        try:
+            import web_server
+            web_server.broadcast_event("status_change", {"profile": target})
+        except Exception:
+            pass
+        return True, output_msg
+    else:
+        err_msg = res.stderr.strip() or res.stdout.strip() or f"Failed to set profile '{target}'."
+        return False, err_msg
+
+
+def main():
+    if len(sys.argv) < 2 or sys.argv[1] in ("list", "ls", "--list"):
+        print(list_profiles())
+        return
+
+    action = sys.argv[1].lower()
+    if action in ("get", "current", "show"):
+        print(f"Active Hermes Profile: {get_current_profile()}")
+        return
+
+    if action in ("set", "use", "change") and len(sys.argv) >= 3:
+        target = sys.argv[2]
+        ok, msg = set_profile(target)
+        print(msg)
+    else:
+        # Treat single argument as target profile
+        target = sys.argv[1]
+        ok, msg = set_profile(target)
+        print(msg)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/bin/session_tool.py b/bin/session_tool.py
new file mode 100644
index 0000000..4f1b19e
--- /dev/null
+++ b/bin/session_tool.py
@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+"""CLI helper to inspect and reset Hermes voice agent sessions."""
+
+import json
+import sys
+from pathlib import Path
+
+# Add VoiceAgent1 project root to sys.path
+project_root = Path(__file__).resolve().parent.parent
+if str(project_root) not in sys.path:
+    sys.path.insert(0, str(project_root))
+
+SESSION_FILE_NAME = ".hermes-voice-session.json"
+
+
+def get_session_file(app_dir: Path | None = None) -> Path:
+    base_dir = app_dir or project_root
+    return base_dir / SESSION_FILE_NAME
+
+
+def get_active_session_id(app_dir: Path | None = None) -> str | None:
+    session_file = get_session_file(app_dir)
+    if session_file.exists():
+        try:
+            data = json.loads(session_file.read_text())
+            sid = data.get("session_id")
+            if sid and isinstance(sid, str):
+                return sid.strip()
+        except Exception:
+            pass
+    return None
+
+
+def reset_session(app_dir: Path | None = None) -> tuple[bool, str]:
+    session_file = get_session_file(app_dir)
+    deleted = False
+    if session_file.exists():
+        try:
+            session_file.unlink()
+            deleted = True
+        except Exception as e:
+            return False, f"Could not remove session file: {e}"
+
+    msg = "Session reset successfully. A fresh Hermes session will start on the next turn."
+    if not deleted:
+        msg = "No active session file found. Next turn will start with a fresh session."
+
+    try:
+        import web_server
+        web_server.broadcast_event("session_reset", {"message": msg})
+    except Exception:
+        pass
+
+    return True, msg
+
+
+def main():
+    app_dir = project_root
+
+    if len(sys.argv) < 2 or sys.argv[1] in ("get", "info", "current", "show"):
+        sid = get_active_session_id(app_dir)
+        if sid:
+            print(f"Active Session ID: {sid}")
+        else:
+            print("No active Hermes session (a new session will start on the next turn).")
+        return
+
+    action = sys.argv[1].lower()
+    if action in ("reset", "new", "clear"):
+        ok, msg = reset_session(app_dir)
+        print(msg)
+    else:
+        print(f"Unknown action: {sys.argv[1]}. Usage: python bin/session_tool.py [get|reset]")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/bot.py b/bot.py
index ddd3998..96e71be 100644
--- a/bot.py
+++ b/bot.py
@@ -82,6 +82,9 @@ say them:
 - Use your available tools (listing directories, searching, reading files, shell execution) whenever the user asks about files, commands, CLI tools (such as Paseo), or workspace tasks.
 - You can change your own voice! If the user asks to list available voices or switch voice, run `python bin/voice_tool.py list` or `python bin/voice_tool.py set <voice_name>` (voices: af_heart, af_bella, am_michael, am_fenrir, am_puck, bf_emma, bm_george, Moira, Daniel).
 - You can change your AI model on the fly! If the user asks to list available models or change model, run `python bin/model_tool.py list` or `python bin/model_tool.py set <model_name>` (models: luna, gemma, deepseek, gpt-oss, sonnet, etc.).
+- You can reset or start a fresh conversation session! If the user asks to start a fresh session, reset the conversation, or clear session context, run `python bin/session_tool.py reset`.
+- You can switch Hermes agent profiles! If the user asks to list Hermes profiles or switch profile, run `python bin/profile_tool.py list` or `python bin/profile_tool.py set <profile_name>`.
+- You can change the running microphone and speakers independently. For requests such as “use AirPods”, “switch to Mac speakers”, or “use the Mac default mic”, run `python bin/audio_tool.py list` then `python bin/audio_tool.py set input|output <device-name-or-index|default>`. Report the command result plainly; do not claim a device changed if the tool says it is unavailable.
 - You can open files visually for the user in the Companion Web UI drawer! Run `python bin/web_tool.py show <filepath>`.
 - You can open links or the Companion Web UI in the default browser! Run `python bin/web_tool.py open <url>`.
 - Keep implementation details and tool activity silent in the spoken channel. The user can see technical progress in the logs or Companion Web UI; only speak the useful conversational response.
@@ -571,6 +574,21 @@ async def main() -> int:
         logger.info(f"Created {workspace}")
     logger.info(f"Workspace: {workspace}")
 
+    async def on_audio_device_event(snapshot) -> None:
+        """Keep native route changes observable without touching conversation state."""
+        logger.info(
+            "Audio device event "
+            f"generation={snapshot.generation} reason={snapshot.reason.value} "
+            f"input={snapshot.default_input_uid!r} output={snapshot.default_output_uid!r}"
+        )
+        if not getattr(args, "no_web", False):
+            web_server.broadcast_event("audio_device", {
+                "generation": snapshot.generation,
+                "reason": snapshot.reason.value,
+                "input_uid": snapshot.default_input_uid,
+                "output_uid": snapshot.default_output_uid,
+            })
+
     transport = SoundDeviceTransport(
         SoundDeviceTransportParams(
             audio_in_enabled=True,
@@ -579,7 +597,8 @@ async def main() -> int:
             audio_out_sample_rate=TTS_SAMPLE_RATE,
             input_device=as_device(args.input_device),
             output_device=as_device(args.output_device),
-        )
+        ),
+        device_event_sink=on_audio_device_event,
     )
 
     brain = None
@@ -603,7 +622,7 @@ async def main() -> int:
     model_manager = ModelManager(workspace)
     if not getattr(args, "no_web", False):
         await web_server.start_server(workspace, port=getattr(args, "web_port", 8888))
-        web_server.set_managers(workspace, model_manager, voice_manager)
+        web_server.set_managers(workspace, model_manager, voice_manager, audio_controller=transport)
 
     llm = build_llm(
         args,
@@ -674,7 +693,7 @@ async def main() -> int:
             await worker.queue_frames(frames)
 
     if not getattr(args, "no_web", False):
-        web_server.set_managers(workspace, model_manager, voice_manager, input_callback=on_web_input)
+        web_server.set_managers(workspace, model_manager, voice_manager, input_callback=on_web_input, audio_controller=transport)
 
     if args.greeting:
         await worker.queue_frames([TTSSpeakFrame(args.greeting)])
diff --git a/build_app.sh b/build_app.sh
index 9cffcea..29f9d6b 100644
--- a/build_app.sh
+++ b/build_app.sh
@@ -5,17 +5,84 @@ set -euo pipefail
 HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 cd "$HERE"
 
-echo "=== 1. Building Swift Helper & Launcher Binaries ==="
-bash swift/build.sh
+FORCE=0
+for arg in "$@"; do
+    if [ "$arg" = "-f" ] || [ "$arg" = "--force" ]; then
+        FORCE=1
+    fi
+done
 
 APP_NAME="VoiceAgent"
 DIST_DIR="$HERE/dist"
 APP_BUNDLE="$DIST_DIR/$APP_NAME.app"
+INSTALLED_APP="/Applications/VoiceAgent.app"
 CONTENTS_DIR="$APP_BUNDLE/Contents"
 MACOS_DIR="$CONTENTS_DIR/MacOS"
 RESOURCES_DIR="$CONTENTS_DIR/Resources"
 SRC_DIR="$RESOURCES_DIR/src"
 
+ENV_FILE="$HOME/.voiceagent.env"
+echo "=== 0. Updating Local Environment Config ($ENV_FILE) ==="
+mkdir -p "$(dirname "$ENV_FILE")"
+touch "$ENV_FILE"
+
+# Helper to update or append key=val in .env file
+set_env_var() {
+    local key="$1"
+    local val="$2"
+    if grep -q "^${key}=" "$ENV_FILE" 2>/dev/null; then
+        # Replace existing line using python helper for clean string replacement
+        python3 -c "
+import sys, re
+path, k, v = sys.argv[1], sys.argv[2], sys.argv[3]
+with open(path, 'r') as f: content = f.read()
+new_content = re.sub(r'^' + re.escape(k) + r'=.*$', f'{k}={v}', content, flags=re.MULTILINE)
+with open(path, 'w') as f: f.write(new_content)
+" "$ENV_FILE" "$key" "$val"
+    else
+        echo "${key}=${val}" >> "$ENV_FILE"
+    fi
+}
+
+set_env_var "VOICEAGENT_DIR" "$HERE"
+set_env_var "VOICEAGENT_PYTHON" "$HERE/.venv/bin/python"
+echo "Configured VOICEAGENT_DIR=$HERE in $ENV_FILE"
+
+echo "=== 1. Building Swift Helper Binaries ==="
+bash swift/build.sh "$@"
+
+INSTALLED_LAUNCHER="$INSTALLED_APP/Contents/MacOS/VoiceAgent"
+NEED_REBUILD=0
+
+if [ "$FORCE" -eq 1 ] || [ ! -f "$INSTALLED_LAUNCHER" ]; then
+    NEED_REBUILD=1
+elif [ "$HERE/swift/VoiceAgentLauncher.swift" -nt "$INSTALLED_LAUNCHER" ]; then
+    NEED_REBUILD=1
+elif [ "$HERE/swift/SpeechHelper.swift" -nt "$INSTALLED_LAUNCHER" ]; then
+    NEED_REBUILD=1
+fi
+
+if [ "$NEED_REBUILD" -eq 0 ]; then
+    echo "=== [SKIPPED BINARY REBUILD & CODESIGN] ==="
+    echo "Native launcher binary is up to date."
+    echo "Copying updated python resources without modifying code signature..."
+    
+    mkdir -p "$SRC_DIR"
+    cp "$HERE"/*.py "$SRC_DIR/" 2>/dev/null || true
+    cp -R "$HERE/bin" "$SRC_DIR/" 2>/dev/null || true
+    
+    if [ -d "$INSTALLED_APP/Contents/Resources/src" ]; then
+        cp "$HERE"/*.py "$INSTALLED_APP/Contents/Resources/src/" 2>/dev/null || true
+        cp -R "$HERE/bin" "$INSTALLED_APP/Contents/Resources/src/" 2>/dev/null || true
+    fi
+
+    echo "=========================================================="
+    echo "Python changes deployed cleanly! App binary signature unchanged."
+    echo "macOS permissions preserved for: $INSTALLED_APP"
+    echo "=========================================================="
+    exit 0
+fi
+
 echo "=== 2. Creating macOS App Bundle Structure ==="
 rm -rf "$APP_BUNDLE"
 mkdir -p "$MACOS_DIR"
@@ -77,12 +144,12 @@ echo "=== 6. Code-signing App Bundle ==="
 codesign -s - --deep --force "$APP_BUNDLE"
 
 echo "=== 7. Installing to /Applications ==="
-rm -rf /Applications/VoiceAgent.app
+rm -rf "$INSTALLED_APP"
 cp -R "$APP_BUNDLE" /Applications/
-codesign -s - --deep --force /Applications/VoiceAgent.app
+codesign -s - --deep --force "$INSTALLED_APP"
 
 echo "=========================================================="
 echo "Successfully built and installed VoiceAgent.app to:"
-echo "1. /Applications/VoiceAgent.app"
+echo "1. $INSTALLED_APP"
 echo "2. $APP_BUNDLE"
 echo "=========================================================="
diff --git a/hermes_llm.py b/hermes_llm.py
index 257a8eb..e888074 100644
--- a/hermes_llm.py
+++ b/hermes_llm.py
@@ -95,16 +95,24 @@ def find_hermes_cli() -> str | None:
     return shutil.which("hermes")
 
 
-async def ensure_hermes_server(port: int = 8642) -> tuple[bool, str]:
-    """Ensure Hermes gateway server daemon is available on port."""
+async def check_hermes_server_active(port: int = 8642) -> tuple[bool, str]:
+    """Check if Hermes gateway server daemon is responding to health requests."""
     url = f"http://localhost:{port}/api/health"
     try:
-        async with aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=2.0)) as session:
+        async with aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=1.5)) as session:
             async with session.get(url) as resp:
                 if resp.status == 200:
                     return True, f"Hermes server active on http://localhost:{port}"
     except Exception:
         pass
+    return False, "Hermes server daemon not active"
+
+
+async def ensure_hermes_server(port: int = 8642) -> tuple[bool, str]:
+    """Ensure Hermes gateway server daemon or CLI binary is available."""
+    active, msg = await check_hermes_server_active(port)
+    if active:
+        return True, msg
 
     cli = find_hermes_cli()
     if not cli:
@@ -146,6 +154,7 @@ class HermesLLM(FrameProcessor):
         self._cli_path = find_hermes_cli() or "hermes"
         self._use_server = use_server
         self._session_renamed = False
+        self._http_session: aiohttp.ClientSession | None = None
 
         # Keep the conversation lineage with the workspace. A single global
         # session file can make two voice-agent workspaces resume each other's
@@ -157,6 +166,37 @@ class HermesLLM(FrameProcessor):
         if self._session_id:
             logger.info(f"Loaded existing Hermes session ID: {self._session_id}")
 
+    def reset_session(self):
+        """Reset active session so a fresh session starts on the next turn."""
+        logger.info("Resetting active Hermes session state...")
+        self._session_id = None
+        self._session_renamed = False
+        self._history.clear()
+        try:
+            if self._session_state_file.exists():
+                self._session_state_file.unlink()
+        except Exception as e:
+            logger.warning(f"Could not remove session file during reset: {e}")
+
+    def _sync_disk_session(self):
+        """Sync in-memory session ID with disk file state prior to each turn."""
+        disk_sid = self._load_session_id()
+        if disk_sid != self._session_id:
+            logger.info(f"Hermes session state updated from disk: {self._session_id} -> {disk_sid}")
+            self._session_id = disk_sid
+            self._session_renamed = False
+            self._history.clear()
+
+    async def _get_http_session(self) -> aiohttp.ClientSession:
+        if self._http_session is None or self._http_session.closed:
+            self._http_session = aiohttp.ClientSession()
+        return self._http_session
+
+    async def _close_http_session(self):
+        if self._http_session and not self._http_session.closed:
+            await self._http_session.close()
+            self._http_session = None
+
     def _load_session_id(self) -> str | None:
         if self._session_state_file.exists():
             try:
@@ -219,6 +259,7 @@ class HermesLLM(FrameProcessor):
             logger.info(f"Hermes LLM engine initialized: {reason}")
         elif isinstance(frame, (EndFrame, CancelFrame)):
             await self._cancel_turn()
+            await self._close_http_session()
             await self.push_frame(frame, direction)
         elif isinstance(frame, InterruptionFrame):
             await self._cancel_turn()
@@ -289,6 +330,7 @@ class HermesLLM(FrameProcessor):
 
     async def _run_turn(self, utterance: str):
         self._sync_disk_model()
+        self._sync_disk_session()
         self._history.append({"role": "user", "content": utterance})
 
         await self.push_frame(LLMFullResponseStartFrame())
@@ -313,7 +355,7 @@ class HermesLLM(FrameProcessor):
     async def _run_turn_server(self, utterance: str, chunks: list[str]):
         """Run turn via Hermes Server / Gateway HTTP API if available."""
         try:
-            ok, _ = await ensure_hermes_server(self._port)
+            ok, _ = await check_hermes_server_active(self._port)
             if not ok:
                 raise RuntimeError("Hermes server daemon unavailable")
 
@@ -325,8 +367,8 @@ class HermesLLM(FrameProcessor):
             if self._model and self._model.lower() not in ("default", "none", ""):
                 payload["model"] = self._model
 
-            async with aiohttp.ClientSession() as session:
-                async with session.post(url, json=payload) as resp:
+            session = await self._get_http_session()
+            async with session.post(url, json=payload) as resp:
                     if resp.status == 200:
                         data = await resp.json()
                         text_val = data.get("reply") or data.get("text") or data.get("content", "")
diff --git a/sounddevice_transport.py b/sounddevice_transport.py
index 0f77e76..3639c8d 100644
--- a/sounddevice_transport.py
+++ b/sounddevice_transport.py
@@ -8,6 +8,8 @@ identical to the upstream transport.
 """
 
 import asyncio
+import inspect
+import sys
 from concurrent.futures import ThreadPoolExecutor
 
 import sounddevice as sd
@@ -18,6 +20,7 @@ from pipecat.processors.frame_processor import FrameProcessor
 from pipecat.transports.base_input import BaseInputTransport
 from pipecat.transports.base_output import BaseOutputTransport
 from pipecat.transports.base_transport import BaseTransport, TransportParams
+from audio_device_monitor import AudioDeviceSnapshot, create_macos_audio_monitor
 
 
 class SoundDeviceTransportParams(TransportParams):
@@ -36,11 +39,14 @@ class SoundDeviceInputTransport(BaseInputTransport):
     """Captures microphone audio and pushes it into the pipeline."""
 
     _params: SoundDeviceTransportParams
+    _transport: "SoundDeviceTransport"
 
     def __init__(self, params: SoundDeviceTransportParams):
         super().__init__(params)
         self._in_stream: sd.RawInputStream | None = None
         self._sample_rate = 0
+        self._stream_generation = 0
+        self._stream_lock = asyncio.Lock()
 
     async def start(self, frame: StartFrame):
         await super().start(frame)
@@ -51,29 +57,74 @@ class SoundDeviceInputTransport(BaseInputTransport):
         self._sample_rate = self._params.audio_in_sample_rate or frame.audio_in_sample_rate
         blocksize = int(self._sample_rate / 100) * 2  # 20ms
 
-        self._in_stream = sd.RawInputStream(
-            samplerate=self._sample_rate,
-            blocksize=blocksize,
-            device=self._params.input_device,
-            channels=self._params.audio_in_channels,
-            dtype="int16",
-            callback=self._audio_in_callback,
-        )
-        self._in_stream.start()
-
-        device_name = sd.query_devices(self._in_stream.device, "input")["name"]
-        logger.info(f"Microphone: {device_name} @ {self._sample_rate} Hz")
+        await self._open_stream()
 
         await self.set_transport_ready(frame)
 
+        if hasattr(self, "_transport"):
+            await self._transport.start_device_monitor(self)
+
+    async def reopen(self, *, device=None):
+        """Recreate an unset-device stream so PortAudio resolves the new default."""
+        if not self._in_stream:
+            return
+        async with self._stream_lock:
+            old_stream = self._in_stream
+            old_device = old_stream.device
+            # Fail before disrupting an otherwise healthy conversation whenever
+            # PortAudio can already tell us that the new default is unavailable.
+            sd.check_input_settings(
+                device=self._params.input_device if device is None else device, samplerate=self._sample_rate,
+                channels=self._params.audio_in_channels, dtype="int16",
+            )
+            self._stream_generation += 1  # makes callbacks from the old stream inert
+            try:
+                old_stream.stop()
+                old_stream.close()
+                self._in_stream = None
+                await self._open_stream(device=device)
+            except Exception as exc:
+                logger.warning(f"Audio input route change failed; restoring prior stream: {type(exc).__name__}")
+                try:
+                    self._in_stream = None
+                    await self._open_stream(device=old_device)
+                except Exception as restore_exc:
+                    logger.error(f"Audio input fallback unavailable: {type(restore_exc).__name__}")
+                raise
+
+    async def _open_stream(self, *, device=None):
+        blocksize = int(self._sample_rate / 100) * 2
+        self._stream_generation += 1
+        generation = self._stream_generation
+        stream = sd.RawInputStream(
+            samplerate=self._sample_rate, blocksize=blocksize,
+            device=self._params.input_device if device is None else device,
+            channels=self._params.audio_in_channels, dtype="int16",
+            callback=lambda *args: self._audio_in_callback(generation, *args),
+        )
+        try:
+            stream.start()
+        except Exception:
+            stream.close()
+            raise
+        self._in_stream = stream
+        device_name = sd.query_devices(self._in_stream.device, "input")["name"]
+        logger.info(f"Microphone: {device_name} @ {self._sample_rate} Hz")
+
     async def cleanup(self):
         await super().cleanup()
-        if self._in_stream:
-            self._in_stream.stop()
-            self._in_stream.close()
-            self._in_stream = None
+        async with self._stream_lock:
+            self._stream_generation += 1
+            if self._in_stream:
+                self._in_stream.stop()
+                self._in_stream.close()
+                self._in_stream = None
+        if hasattr(self, "_transport"):
+            await self._transport.stop_device_monitor(self)
 
-    def _audio_in_callback(self, indata, frame_count, time_info, status):
+    def _audio_in_callback(self, generation, indata, frame_count, time_info, status):
+        if generation != self._stream_generation:
+            return
         if status:
             logger.trace(f"Audio input status: {status}")
 
@@ -83,7 +134,16 @@ class SoundDeviceInputTransport(BaseInputTransport):
             num_channels=self._params.audio_in_channels,
         )
 
-        asyncio.run_coroutine_threadsafe(self.push_audio_frame(frame), self.get_event_loop())
+        asyncio.run_coroutine_threadsafe(
+            self._push_audio_frame_if_current(generation, frame), self.get_event_loop()
+        )
+
+    async def _push_audio_frame_if_current(self, generation, frame):
+        """Serialize frame delivery with replacement so a closed route cannot leak audio."""
+        async with self._stream_lock:
+            if generation != self._stream_generation:
+                return
+            await self.push_audio_frame(frame)
 
 
 class SoundDeviceOutputTransport(BaseOutputTransport):
@@ -97,6 +157,7 @@ class SoundDeviceOutputTransport(BaseOutputTransport):
         self._sample_rate = 0
         # Writes are serialized by the pipeline, so one worker is enough.
         self._executor = ThreadPoolExecutor(max_workers=1)
+        self._stream_lock = asyncio.Lock()
 
     async def start(self, frame: StartFrame):
         await super().start(frame)
@@ -105,53 +166,258 @@ class SoundDeviceOutputTransport(BaseOutputTransport):
             return
 
         self._sample_rate = self._params.audio_out_sample_rate or frame.audio_out_sample_rate
+        await self._open_stream()
 
-        self._out_stream = sd.RawOutputStream(
+        await self.set_transport_ready(frame)
+        if hasattr(self, "_transport"):
+            await self._transport.start_device_monitor(self)
+
+    async def reopen(self, *, device=None):
+        """Recreate an unset-device stream so PortAudio resolves the new default."""
+        if not self._out_stream:
+            return
+        async with self._stream_lock:
+            old_stream = self._out_stream
+            old_device = old_stream.device
+            # Keep the current output route intact when the selected default
+            # cannot satisfy this stream's negotiated format.
+            sd.check_output_settings(
+                device=self._params.output_device if device is None else device, samplerate=self._sample_rate,
+                channels=self._params.audio_out_channels, dtype="int16",
+            )
+            try:
+                old_stream.stop()
+                old_stream.close()
+                self._out_stream = None
+                await self._open_stream(device=device)
+            except Exception as exc:
+                logger.warning(f"Audio output route change failed; restoring prior stream: {type(exc).__name__}")
+                try:
+                    self._out_stream = None
+                    await self._open_stream(device=old_device)
+                except Exception as restore_exc:
+                    logger.error(f"Audio output fallback unavailable: {type(restore_exc).__name__}")
+                raise
+
+    async def _open_stream(self, *, device=None):
+        stream = sd.RawOutputStream(
             samplerate=self._sample_rate,
-            device=self._params.output_device,
-            channels=self._params.audio_out_channels,
-            dtype="int16",
+            device=self._params.output_device if device is None else device,
+            channels=self._params.audio_out_channels, dtype="int16",
         )
-        self._out_stream.start()
-
+        try:
+            stream.start()
+        except Exception:
+            stream.close()
+            raise
+        self._out_stream = stream
         device_name = sd.query_devices(self._out_stream.device, "output")["name"]
         logger.info(f"Speaker: {device_name} @ {self._sample_rate} Hz")
 
-        await self.set_transport_ready(frame)
-
     async def cleanup(self):
         await super().cleanup()
-        if self._out_stream:
-            self._out_stream.stop()
-            self._out_stream.close()
-            self._out_stream = None
+        async with self._stream_lock:
+            if self._out_stream:
+                self._out_stream.stop()
+                self._out_stream.close()
+                self._out_stream = None
+        if hasattr(self, "_transport"):
+            await self._transport.stop_device_monitor(self)
 
     async def write_audio_frame(self, frame: OutputAudioRawFrame) -> bool:
-        if not self._out_stream:
-            return False
-        await self.get_event_loop().run_in_executor(
-            self._executor, self._out_stream.write, frame.audio
-        )
+        async with self._stream_lock:
+            if not self._out_stream:
+                return False
+            await self.get_event_loop().run_in_executor(
+                self._executor, self._out_stream.write, frame.audio
+            )
         return True
 
 
 class SoundDeviceTransport(BaseTransport):
     """Local microphone + speaker transport."""
 
-    def __init__(self, params: SoundDeviceTransportParams):
+    def __init__(self, params: SoundDeviceTransportParams, *, device_monitor=None,
+                 device_event_sink=None):
         super().__init__()
         self._params = params
         self._input: SoundDeviceInputTransport | None = None
         self._output: SoundDeviceOutputTransport | None = None
+        self._device_monitor = device_monitor
+        self._device_event_sink = device_event_sink
+        self._last_snapshot: AudioDeviceSnapshot | None = None
+        self._restart_lock = asyncio.Lock()
+        self._monitor_started = False
+        self._monitor_owners: set[object] = set()
+        self._monitor_lock = asyncio.Lock()
+
+    def _monitor_if_needed(self):
+        if self._device_monitor is not None:
+            return self._device_monitor
+        if sys.platform != "darwin":
+            return None
+        if self._params.input_device is None or self._params.output_device is None:
+            try:
+                self._device_monitor = create_macos_audio_monitor()
+            except Exception as exc:
+                logger.warning(f"Audio default monitoring unavailable: {exc}")
+        return self._device_monitor
+
+    async def start_device_monitor(self, owner=None):
+        """Keep the shared monitor running while any transport side is active."""
+        owner = self if owner is None else owner
+        async with self._monitor_lock:
+            self._monitor_owners.add(owner)
+            if self._monitor_started:
+                return
+            monitor = self._monitor_if_needed()
+            if monitor:
+                await monitor.start(self._on_device_change)
+                self._monitor_started = True
+
+    async def stop_device_monitor(self, owner=None):
+        """Release one transport side; stop only after the final release."""
+        owner = self if owner is None else owner
+        async with self._monitor_lock:
+            self._monitor_owners.discard(owner)
+            if self._monitor_owners or not self._device_monitor or not self._monitor_started:
+                return
+            await self._device_monitor.stop()
+            self._monitor_started = False
+
+    async def _on_device_change(self, snapshot: AudioDeviceSnapshot):
+        if self._last_snapshot and snapshot.generation <= self._last_snapshot.generation:
+            logger.debug(f"Ignoring stale audio route event generation={snapshot.generation}")
+            return
+        if self._device_event_sink:
+            try:
+                result = self._device_event_sink(snapshot)
+                if inspect.isawaitable(result):
+                    await result
+            except Exception as exc:
+                logger.warning(f"Audio device event sink failed: {type(exc).__name__}")
+        old = self._last_snapshot
+        self._last_snapshot = snapshot
+        if old is None:
+            return
+        input_changed = old.default_input_uid != snapshot.default_input_uid
+        output_changed = old.default_output_uid != snapshot.default_output_uid
+        if not (input_changed or output_changed):
+            return
+        async with self._restart_lock:
+            if input_changed and self._params.input_device is None and self._input:
+                try:
+                    await self._reopen_default(self._input, snapshot, snapshot.default_input_uid, "input")
+                except Exception as exc:
+                    logger.warning(f"Audio input route refresh failed: {type(exc).__name__}")
+            if output_changed and self._params.output_device is None and self._output:
+                try:
+                    await self._reopen_default(self._output, snapshot, snapshot.default_output_uid, "output")
+                except Exception as exc:
+                    logger.warning(f"Audio output route refresh failed: {type(exc).__name__}")
+
+    async def _reopen_default(self, stream, snapshot: AudioDeviceSnapshot, uid: str | None, direction: str) -> None:
+        # Empty snapshots are supported for legacy/injected monitors. Native
+        # snapshots always carry devices and therefore get an explicit index.
+        if not snapshot.devices:
+            await stream.reopen()
+            return
+        await stream.reopen(device=self._portaudio_device(snapshot, uid, direction))
+
+    @staticmethod
+    def _portaudio_device(snapshot: AudioDeviceSnapshot, uid: str | None, direction: str) -> int:
+        """Map Core Audio's current default to an explicit PortAudio index.
+
+        ``device=None`` in a long-lived sounddevice process retains PortAudio's
+        startup default. Reopening with the current index is what makes a
+        default-device event actually move the live stream.
+        """
+        if not uid or uid not in snapshot.devices:
+            raise RuntimeError(f"No available Core Audio default {direction} device")
+        native = snapshot.devices[uid]
+        capability = "max_input_channels" if direction == "input" else "max_output_channels"
+        matches = [index for index, candidate in enumerate(sd.query_devices())
+                   if candidate["name"] == native.name and candidate[capability] > 0]
+        if len(matches) != 1:
+            raise RuntimeError(f"No unique PortAudio {direction} device for {native.name!r}: {matches}")
+        return matches[0]
+
+    @staticmethod
+    def available_devices() -> list[dict]:
+        return [
+            {"id": index, "name": device["name"], "input": bool(device["max_input_channels"]),
+             "output": bool(device["max_output_channels"])}
+            for index, device in enumerate(sd.query_devices())
+            if device["max_input_channels"] or device["max_output_channels"]
+        ]
+
+    @classmethod
+    def _select_device(cls, request: int | str, direction: str) -> int:
+        capability = "input" if direction == "input" else "output"
+        devices = cls.available_devices()
+        if isinstance(request, int) or (isinstance(request, str) and request.isdecimal()):
+            index = int(request)
+            if any(device["id"] == index and device[capability] for device in devices):
+                return index
+        else:
+            needle = str(request).casefold().strip()
+            matches = [device["id"] for device in devices
+                       if device[capability] and needle in device["name"].casefold()]
+            if len(matches) == 1:
+                return matches[0]
+        raise ValueError(f"No unique available {direction} device matches {request!r}")
+
+    async def set_runtime_device(self, direction: str, request: int | str | None) -> dict:
+        """Pin one route live, or pass ``default``/None to follow macOS again."""
+        if direction not in {"input", "output"}:
+            raise ValueError("direction must be input or output")
+        following_default = request is None or str(request).casefold().strip() in {"default", "mac default", "system default"}
+        selected = None if following_default else self._select_device(request, direction)  # type: ignore[arg-type]
+        previous = self._params.input_device if direction == "input" else self._params.output_device
+        async with self._restart_lock:
+            stream = self._input if direction == "input" else self._output
+            try:
+                # Temporarily clear this pin so an all-pinned transport can
+                # create its native monitor and take a fresh default snapshot.
+                if following_default:
+                    if direction == "input":
+                        self._params.input_device = None
+                    else:
+                        self._params.output_device = None
+                    await self.start_device_monitor()
+                if stream:
+                    if following_default:
+                        snapshot = self._last_snapshot
+                        if not snapshot:
+                            raise RuntimeError(f"No macOS default-{direction} snapshot is available yet")
+                        uid = snapshot.default_input_uid if direction == "input" else snapshot.default_output_uid
+                        await self._reopen_default(stream, snapshot, uid, direction)
+                    else:
+                        await stream.reopen(device=selected)
+                if direction == "input":
+                    self._params.input_device = selected
+                else:
+                    self._params.output_device = selected
+            except Exception:
+                if direction == "input":
+                    self._params.input_device = previous
+                else:
+                    self._params.output_device = previous
+                raise
+        name = "macOS default" if following_default else next(device["name"] for device in self.available_devices() if device["id"] == selected)
+        logger.info(f"Runtime {direction} device changed to {name}")
+        return {"direction": direction, "device": selected, "name": name, "following_default": following_default}
 
     def input(self) -> FrameProcessor:
         if not self._input:
             self._input = SoundDeviceInputTransport(self._params)
+            self._input._transport = self
         return self._input
 
     def output(self) -> FrameProcessor:
         if not self._output:
             self._output = SoundDeviceOutputTransport(self._params)
+            self._output._transport = self
         return self._output
 
 
diff --git a/swift/VoiceAgentLauncher.swift b/swift/VoiceAgentLauncher.swift
index 91e39ce..52477dd 100644
--- a/swift/VoiceAgentLauncher.swift
+++ b/swift/VoiceAgentLauncher.swift
@@ -4,15 +4,53 @@ import Foundation
 struct VoiceAgentLauncher {
     static func main() {
         let fileManager = FileManager.default
-        let projDir = "/Users/adolforeyna/Projects/VoiceAgent1"
+        let homeDir = fileManager.homeDirectoryForCurrentUser.path
+        
+        // Load configuration from .env files if present
+        var envConfig = [String: String]()
+        let envPaths = [
+            "\(homeDir)/.voiceagent.env",
+            "\(homeDir)/.config/voiceagent/env",
+            "\(homeDir)/.env"
+        ]
+        
+        for envPath in envPaths {
+            if let content = try? String(contentsOfFile: envPath, encoding: .utf8) {
+                for line in content.components(separatedBy: .newlines) {
+                    let trimmed = line.trimmingCharacters(in: .whitespaces)
+                    if trimmed.isEmpty || trimmed.hasPrefix("#") { continue }
+                    let parts = trimmed.split(separator: "=", maxSplits: 1).map { String($0).trimmingCharacters(in: .whitespacesAndNewlines) }
+                    if parts.count == 2 {
+                        let key = parts[0]
+                        var val = parts[1]
+                        if (val.hasPrefix("\"") && val.hasSuffix("\"")) || (val.hasPrefix("'") && val.hasSuffix("'")) {
+                            val = String(val.dropFirst().dropLast())
+                        }
+                        envConfig[key] = val
+                    }
+                }
+            }
+        }
+        
+        let defaultProjDir = "/Users/adolforeyna/Projects/VoiceAgent1"
+        let configuredProjDir = ProcessInfo.processInfo.environment["VOICEAGENT_DIR"]
+            ?? envConfig["VOICEAGENT_DIR"]
+            ?? envConfig["WORKSPACE_DIR"]
+            ?? defaultProjDir
         
         let bundleResPath = Bundle.main.resourcePath ?? ""
         let bundledSrcPath = "\(bundleResPath)/src"
         
-        let workDir = fileManager.fileExists(atPath: projDir) ? projDir : bundledSrcPath
-        let pythonBin = "\(projDir)/.venv/bin/python"
+        let workDir = fileManager.fileExists(atPath: configuredProjDir) ? configuredProjDir : bundledSrcPath
+        
+        let defaultPythonBin = "\(workDir)/.venv/bin/python"
+        let configuredPython = ProcessInfo.processInfo.environment["VOICEAGENT_PYTHON"]
+            ?? envConfig["VOICEAGENT_PYTHON"]
+            ?? envConfig["PYTHON_PATH"]
+            ?? defaultPythonBin
+            
         let fallbackPython = "/usr/bin/python3"
-        let targetPython = fileManager.fileExists(atPath: pythonBin) ? pythonBin : fallbackPython
+        let targetPython = fileManager.fileExists(atPath: configuredPython) ? configuredPython : fallbackPython
         let targetScript = "\(workDir)/app_main.py"
 
         setenv("SSL_CERT_FILE", "/etc/ssl/cert.pem", 1)
diff --git a/swift/build.sh b/swift/build.sh
index f6fc79d..eb8be29 100755
--- a/swift/build.sh
+++ b/swift/build.sh
@@ -9,8 +9,19 @@ set -euo pipefail
 HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 cd "$HERE"
 
-swiftc -O -parse-as-library SpeechHelper.swift -o speech-helper
-echo "built $HERE/speech-helper"
+FORCE=0
+for arg in "$@"; do
+    if [ "$arg" = "-f" ] || [ "$arg" = "--force" ]; then
+        FORCE=1
+    fi
+done
+
+if [ "$FORCE" -eq 1 ] || [ ! -f speech-helper ] || [ SpeechHelper.swift -nt speech-helper ]; then
+    swiftc -O -parse-as-library SpeechHelper.swift -o speech-helper
+    echo "built $HERE/speech-helper"
+else
+    echo "speech-helper is up to date — skipping recompile"
+fi
 
 if ./speech-helper --check >/dev/null 2>&1; then
     echo "speech-helper runs — ./speech-helper --check for details"
@@ -24,12 +35,16 @@ else
     fi
 fi
 
-if swiftc -O -parse-as-library -target arm64-apple-macosx26.0 LLMHelper.swift -o llm-helper 2>/dev/null; then
-    echo "built $HERE/llm-helper"
-    if ./llm-helper --check >/dev/null 2>&1; then
-        echo "llm-helper runs — ./llm-helper --check for details"
+if [ "$FORCE" -eq 1 ] || [ ! -f llm-helper ] || [ LLMHelper.swift -nt llm-helper ]; then
+    if swiftc -O -parse-as-library -target arm64-apple-macosx26.0 LLMHelper.swift -o llm-helper 2>/dev/null; then
+        echo "built $HERE/llm-helper"
+        if ./llm-helper --check >/dev/null 2>&1; then
+            echo "llm-helper runs — ./llm-helper --check for details"
+        fi
+    else
+        echo "could not build llm-helper with FoundationModels; fallback to Python MLX bridge will be available"
     fi
 else
-    echo "could not build llm-helper with FoundationModels; fallback to Python MLX bridge will be available"
+    echo "llm-helper is up to date — skipping recompile"
 fi
 
diff --git a/test_audio_device_monitor.py b/test_audio_device_monitor.py
new file mode 100644
index 0000000..47a1509
--- /dev/null
+++ b/test_audio_device_monitor.py
@@ -0,0 +1,244 @@
+import asyncio
+import sys
+import threading
+import unittest
+
+
+from audio_device_monitor import AudioDevice, AudioDeviceMonitor, DeviceChangeReason
+
+
+class FakeBackend:
+    def __init__(self):
+        self.devices = {}
+        self.input = None
+        self.output = None
+        self.listeners = []
+        self.removed = []
+
+    def enumerate_devices(self):
+        return list(self.devices.values())
+
+    def default_input_uid(self):
+        return self.input
+
+    def default_output_uid(self):
+        return self.output
+
+    def add_listener(self, callback):
+        self.listeners.append(callback)
+        return callback
+
+    def remove_listener(self, token):
+        self.removed.append(token)
+        self.listeners.remove(token)
+
+    def notify(self):
+        # Emulate Core Audio's arbitrary callback thread.
+        threads = [threading.Thread(target=callback) for callback in list(self.listeners)]
+        for thread in threads:
+            thread.start()
+        for thread in threads:
+            thread.join()
+
+
+class AudioDeviceMonitorTests(unittest.IsolatedAsyncioTestCase):
+    def setUp(self):
+        self.backend = FakeBackend()
+        self.mic = AudioDevice("mic", "Microphone", True, False, "built-in")
+        self.speaker = AudioDevice("speaker", "Speaker", False, True, "built-in")
+        self.airpods = AudioDevice("airpods", "AirPods", True, True, "bluetooth")
+        self.backend.devices = {x.uid: x for x in (self.mic, self.speaker)}
+        self.backend.input, self.backend.output = "mic", "speaker"
+
+    async def test_initial_and_independent_default_change(self):
+        events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.01)
+        await monitor.start(events.append)
+        self.assertEqual(events[-1].default_input_uid, "mic")
+
+        self.backend.devices["airpods"] = self.airpods
+        self.backend.output = "airpods"
+        self.backend.notify()
+        await asyncio.sleep(.04)
+        self.assertEqual(len(events), 2)
+        self.assertEqual(events[-1].default_output_uid, "airpods")
+        self.assertEqual(events[-1].default_input_uid, "mic")
+        self.assertEqual(events[-1].reason, DeviceChangeReason.DEFAULT_CHANGED)
+        await monitor.stop()
+
+    async def test_duplicate_burst_is_coalesced(self):
+        events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.03)
+        await monitor.start(events.append)
+        for _ in range(10):
+            self.backend.notify()
+        await asyncio.sleep(.08)
+        self.assertEqual(len(events), 1)  # no actual state change
+        await monitor.stop()
+
+    async def test_unavailable_default_is_none(self):
+        events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.01)
+        await monitor.start(events.append)
+        self.backend.input = "gone"
+        self.backend.notify()
+        await asyncio.sleep(.04)
+        self.assertIsNone(events[-1].default_input_uid)
+        self.assertEqual(events[-1].default_output_uid, "speaker")
+        await monitor.stop()
+
+    async def test_stop_removes_listener_and_blocks_late_callbacks(self):
+        events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.01)
+        await monitor.start(events.append)
+        await monitor.stop()
+        self.assertEqual(len(self.backend.removed), 1)
+        self.backend.input = "gone"
+        self.backend.notify()
+        await asyncio.sleep(.04)
+        self.assertEqual(len(events), 1)
+        await monitor.stop()  # idempotent
+
+    @unittest.skipUnless(sys.platform == "darwin", "Core Audio is macOS-only")
+    def test_native_adapter_uses_coreaudio_uids_not_portaudio_indices(self):
+        """Stable Core Audio identity must survive PortAudio index renumbering."""
+        from audio_device_monitor import NativeMacOSCoreAudioAdapter
+
+        adapter = NativeMacOSCoreAudioAdapter()
+        devices = adapter.enumerate_devices()
+        self.assertTrue(devices)
+        self.assertTrue(all(not device.uid.isdecimal() for device in devices))
+
+
+    async def test_connect_disconnect_replacement_and_profile_events_are_classified(self):
+        events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.001)
+        await monitor.start(events.append)
+
+        self.backend.devices["airpods"] = self.airpods
+        self.backend.notify()
+        await asyncio.sleep(.01)
+        self.assertEqual(events[-1].reason, DeviceChangeReason.DEVICE_ADDED)
+
+        del self.backend.devices["speaker"]
+        self.backend.output = "airpods"
+        self.backend.notify()
+        await asyncio.sleep(.01)
+        self.assertEqual(events[-1].reason, DeviceChangeReason.DEFAULT_CHANGED)
+
+        self.backend.devices["airpods"] = AudioDevice(
+            "airpods", "AirPods Hands-Free", True, True, "bluetooth"
+        )
+        self.backend.notify()
+        await asyncio.sleep(.01)
+        self.assertEqual(events[-1].reason, DeviceChangeReason.PROFILE_CHANGED)
+
+        del self.backend.devices["airpods"]
+        self.backend.output = None
+        self.backend.notify()
+        await asyncio.sleep(.01)
+        self.assertEqual(events[-1].reason, DeviceChangeReason.DEFAULT_CHANGED)
+        self.backend.devices["usb"] = AudioDevice("usb", "USB headset", False, True)
+        self.backend.notify()
+        await asyncio.sleep(.01)
+        del self.backend.devices["usb"]
+        self.backend.notify()
+        await asyncio.sleep(.01)
+        self.assertEqual(events[-1].reason, DeviceChangeReason.DEVICE_REMOVED)
+        self.assertIsNone(events[-1].default_output_uid)
+        await monitor.stop()
+
+    async def test_backend_callback_is_dispatched_on_monitor_event_loop(self):
+        callback_threads = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.001)
+
+        def record(snapshot):
+            callback_threads.append((snapshot, threading.get_ident()))
+
+        await monitor.start(record)
+        loop_thread = threading.get_ident()
+        self.backend.output = "airpods"
+        self.backend.devices["airpods"] = self.airpods
+        self.backend.notify()
+        await asyncio.sleep(.01)
+
+        self.assertEqual(callback_threads[-1][1], loop_thread)
+        await monitor.stop()
+
+    async def test_listener_registration_failure_cleans_up_registered_tokens(self):
+        class FailingBackend(FakeBackend):
+            def add_listener(self, callback):
+                raise RuntimeError("listener registration failed")
+
+        backend = FailingBackend()
+        backend.devices = self.backend.devices
+        backend.input, backend.output = self.backend.input, self.backend.output
+        monitor = AudioDeviceMonitor(backend)
+        with self.assertRaises(RuntimeError):
+            await monitor.start(lambda _snapshot: None)
+        self.assertFalse(monitor._running)
+        self.assertEqual(len(backend.listeners), 0)
+
+    async def test_repeated_start_is_idempotent_and_does_not_duplicate_listener(self):
+        first_events = []
+        second_events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.001)
+
+        await monitor.start(first_events.append)
+        await monitor.start(second_events.append)
+
+        self.assertEqual(len(self.backend.listeners), 1)
+        self.assertEqual(len(first_events), 1)
+        self.assertEqual(second_events, [])
+        await monitor.stop()
+
+    async def test_callback_failure_stops_monitor_and_removes_listener(self):
+        callback_started = asyncio.Event()
+
+        async def failing_callback(_snapshot):
+            callback_started.set()
+            raise RuntimeError("consumer failed")
+
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.001)
+        with self.assertRaises(RuntimeError):
+            await monitor.start(failing_callback)
+        self.assertFalse(monitor._running)
+        self.assertEqual(len(self.backend.listeners), 0)
+        self.assertEqual(len(self.backend.removed), 1)
+        self.assertTrue(callback_started.is_set())
+
+    async def test_callback_failure_after_start_cleans_up_listener(self):
+        callback_started = asyncio.Event()
+        calls = 0
+
+        def failing_after_initial(snapshot):
+            nonlocal calls
+            calls += 1
+            if calls == 2:
+                callback_started.set()
+                raise RuntimeError("consumer failed after notification")
+
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.001)
+        await monitor.start(failing_after_initial)
+        self.backend.output = None
+        self.backend.notify()
+        await asyncio.wait_for(callback_started.wait(), timeout=.2)
+        await asyncio.sleep(.01)
+
+        self.assertFalse(monitor._running)
+        self.assertEqual(len(self.backend.listeners), 0)
+        self.assertEqual(len(self.backend.removed), 1)
+
+    async def test_notifications_after_stop_are_ignored_even_if_callback_was_queued(self):
+        events = []
+        monitor = AudioDeviceMonitor(self.backend, debounce_seconds=.05)
+        await monitor.start(events.append)
+        self.backend.notify()
+        await monitor.stop()
+        await asyncio.sleep(.06)
+        self.assertEqual(len(events), 1)
+        self.assertEqual(len(self.backend.listeners), 0)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/test_profile_tool.py b/test_profile_tool.py
new file mode 100644
index 0000000..cb5ed4d
--- /dev/null
+++ b/test_profile_tool.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+"""Tests for bin/profile_tool.py."""
+
+from bin.profile_tool import get_current_profile, list_profiles, set_profile
+
+
+def test_profile_tool():
+    # Test profile listing
+    profiles_text = list_profiles()
+    assert len(profiles_text) > 0
+
+    # Test current profile getter
+    cur_profile = get_current_profile()
+    assert isinstance(cur_profile, str)
+    assert len(cur_profile) > 0
+
+    # Test setting valid profile (switch back to current profile to be idempotent)
+    ok, msg = set_profile(cur_profile)
+    assert ok
+    assert cur_profile in msg or "Switched" in msg
+    print(f"PASS: test_profile_tool verified (active profile: '{cur_profile}')")
+
+
+if __name__ == "__main__":
+    test_profile_tool()
+    print("\nAll profile tool tests passed successfully!")
diff --git a/test_session_tool.py b/test_session_tool.py
new file mode 100644
index 0000000..c16d282
--- /dev/null
+++ b/test_session_tool.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""Tests for bin/session_tool.py and Hermes session resetting in hermes_llm.py."""
+
+import json
+import tempfile
+from pathlib import Path
+from bin.session_tool import get_active_session_id, reset_session, SESSION_FILE_NAME
+from hermes_llm import HermesLLM
+
+
+def test_session_tool_api():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        workspace = Path(tmpdir)
+        session_file = workspace / SESSION_FILE_NAME
+
+        # Initially no session
+        assert get_active_session_id(workspace) is None
+
+        # Write mock session file
+        session_file.write_text(json.dumps({"session_id": "test_session_123"}) + "\n")
+        assert get_active_session_id(workspace) == "test_session_123"
+
+        # Reset session
+        ok, msg = reset_session(workspace)
+        assert ok
+        assert "reset successfully" in msg.lower() or "no active session" in msg.lower()
+        assert get_active_session_id(workspace) is None
+        assert not session_file.exists()
+
+        # Double reset safely handles non-existent file
+        ok, msg = reset_session(workspace)
+        assert ok
+        print("PASS: test_session_tool_api verified")
+
+
+def test_hermes_llm_session_sync():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        workspace = Path(tmpdir)
+        session_file = workspace / SESSION_FILE_NAME
+
+        # Write mock session ID
+        session_file.write_text(json.dumps({"session_id": "test_session_456"}) + "\n")
+
+        llm = HermesLLM(cwd=workspace)
+        assert llm._session_id == "test_session_456"
+
+        # External reset via tool
+        reset_session(workspace)
+        assert get_active_session_id(workspace) is None
+
+        # Sync disk state in HermesLLM
+        llm._sync_disk_session()
+        assert llm._session_id is None
+
+        # Call reset_session directly on instance
+        session_file.write_text(json.dumps({"session_id": "test_session_789"}) + "\n")
+        llm._sync_disk_session()
+        assert llm._session_id == "test_session_789"
+
+        llm.reset_session()
+        assert llm._session_id is None
+        assert not session_file.exists()
+        print("PASS: test_hermes_llm_session_sync verified")
+
+
+if __name__ == "__main__":
+    test_session_tool_api()
+    test_hermes_llm_session_sync()
+    print("\nAll session tool tests passed successfully!")
diff --git a/test_sounddevice_transport.py b/test_sounddevice_transport.py
new file mode 100644
index 0000000..f4b3135
--- /dev/null
+++ b/test_sounddevice_transport.py
@@ -0,0 +1,350 @@
+import unittest
+from unittest.mock import AsyncMock, patch
+
+from audio_device_monitor import AudioDeviceSnapshot
+from pipecat.frames.frames import StartFrame
+from sounddevice_transport import (
+    SoundDeviceInputTransport,
+    SoundDeviceOutputTransport,
+    SoundDeviceTransport,
+    SoundDeviceTransportParams,
+)
+
+
+class FakeMonitor:
+    def __init__(self):
+        self.start = AsyncMock()
+        self.stop = AsyncMock()
+
+
+class SoundDeviceTransportSwitchTests(unittest.IsolatedAsyncioTestCase):
+    def _transport(self, *, input_device=None, output_device=None):
+        transport = SoundDeviceTransport(
+            SoundDeviceTransportParams(input_device=input_device, output_device=output_device)
+        )
+        transport._input = type("Input", (), {"reopen": AsyncMock()})()
+        transport._output = type("Output", (), {"reopen": AsyncMock()})()
+        return transport
+
+    async def test_default_changes_reopen_only_unset_sides(self):
+        transport = self._transport(input_device=None, output_device="My Speakers")
+
+        await transport._on_device_change(AudioDeviceSnapshot(1, "mic", "speakers"))
+        await transport._on_device_change(AudioDeviceSnapshot(2, "airpods", "airpods"))
+
+        transport._input.reopen.assert_awaited_once_with()
+        transport._output.reopen.assert_not_awaited()
+
+    async def test_default_changes_preserve_each_override_for_all_override_combinations(self):
+        devices = {
+            "old-mic": type("Device", (), {"name": "Built-in Mic", "can_input": True, "can_output": False})(),
+            "old-speaker": type("Device", (), {"name": "Built-in Speaker", "can_input": False, "can_output": True})(),
+            "new-mic": type("Device", (), {"name": "USB Mic", "can_input": True, "can_output": False})(),
+            "new-speaker": type("Device", (), {"name": "USB Speaker", "can_input": False, "can_output": True})(),
+        }
+        portaudio_devices = [
+            {"name": "Built-in Mic", "max_input_channels": 1, "max_output_channels": 0},
+            {"name": "Built-in Speaker", "max_input_channels": 0, "max_output_channels": 2},
+            {"name": "USB Mic", "max_input_channels": 1, "max_output_channels": 0},
+            {"name": "USB Speaker", "max_input_channels": 0, "max_output_channels": 2},
+        ]
+        initial = AudioDeviceSnapshot(1, "old-mic", "old-speaker", devices=devices)
+        changed = AudioDeviceSnapshot(2, "new-mic", "new-speaker", devices=devices)
+
+        with patch("sounddevice_transport.sd.query_devices", return_value=portaudio_devices):
+            for input_override, output_override in (
+                (None, None),
+                ("Pinned Mic", None),
+                (None, "Pinned Speaker"),
+                ("Pinned Mic", "Pinned Speaker"),
+            ):
+                with self.subTest(input_override=input_override, output_override=output_override):
+                    transport = self._transport(
+                        input_device=input_override,
+                        output_device=output_override,
+                    )
+                    await transport._on_device_change(initial)
+                    await transport._on_device_change(changed)
+
+                    if input_override is None:
+                        transport._input.reopen.assert_awaited_once_with(device=2)
+                    else:
+                        transport._input.reopen.assert_not_awaited()
+                    if output_override is None:
+                        transport._output.reopen.assert_awaited_once_with(device=3)
+                    else:
+                        transport._output.reopen.assert_not_awaited()
+
+    async def test_unavailable_default_does_not_reopen_that_side_but_reopens_other_side(self):
+        transport = self._transport()
+        devices = {
+            "mic": type("Device", (), {"name": "Mic", "can_input": True, "can_output": False})(),
+            "speaker": type("Device", (), {"name": "Speaker", "can_input": False, "can_output": True})(),
+            "headphones": type("Device", (), {"name": "Headphones", "can_input": False, "can_output": True})(),
+        }
+        initial = AudioDeviceSnapshot(1, "mic", "speaker", devices=devices)
+        unavailable_input = AudioDeviceSnapshot(2, None, "headphones", devices=devices)
+        with patch("sounddevice_transport.sd.query_devices", return_value=[
+            {"name": "Headphones", "max_input_channels": 0, "max_output_channels": 2},
+        ]):
+            await transport._on_device_change(initial)
+            await transport._on_device_change(unavailable_input)
+
+        transport._input.reopen.assert_not_awaited()
+        transport._output.reopen.assert_awaited_once_with(device=0)
+
+    async def test_input_only_output_only_and_simultaneous_changes_route_independently(self):
+        transport = self._transport()
+        await transport._on_device_change(AudioDeviceSnapshot(1, "mic", "speaker"))
+
+        await transport._on_device_change(AudioDeviceSnapshot(2, "airpods-mic", "speaker"))
+        transport._input.reopen.assert_awaited_once_with()
+        transport._output.reopen.assert_not_awaited()
+
+        await transport._on_device_change(AudioDeviceSnapshot(3, "airpods-mic", "airpods-speaker"))
+        transport._input.reopen.assert_awaited_once_with()
+        transport._output.reopen.assert_awaited_once_with()
+
+        await transport._on_device_change(AudioDeviceSnapshot(4, "mac-mic", "mac-speaker"))
+        self.assertEqual(transport._input.reopen.await_count, 2)
+        self.assertEqual(transport._output.reopen.await_count, 2)
+
+    async def test_default_change_uses_current_portaudio_device_not_process_startup_default(self):
+        transport = self._transport()
+        initial = AudioDeviceSnapshot(1, "built-in-mic", "built-in-speaker")
+        switched = AudioDeviceSnapshot(2, "airpods-input", "airpods-output", devices={
+            "airpods-input": type("Device", (), {"name": "AirPods", "can_input": True, "can_output": False})(),
+            "airpods-output": type("Device", (), {"name": "AirPods", "can_input": False, "can_output": True})(),
+        })
+        with patch("sounddevice_transport.sd.query_devices", return_value=[
+            {"name": "MacBook Air Speakers", "max_input_channels": 0, "max_output_channels": 2},
+            {"name": "AirPods", "max_input_channels": 1, "max_output_channels": 0},
+            {"name": "AirPods", "max_input_channels": 0, "max_output_channels": 2},
+        ]):
+            await transport._on_device_change(initial)
+            await transport._on_device_change(switched)
+
+        transport._input.reopen.assert_awaited_once_with(device=1)
+        transport._output.reopen.assert_awaited_once_with(device=2)
+
+    async def test_input_override_does_not_follow_default_but_output_does(self):
+        params = SoundDeviceTransportParams(input_device="USB Mic", output_device=None)
+        transport = SoundDeviceTransport(params)
+        transport._input = type("Input", (), {"reopen": AsyncMock()})()
+        transport._output = type("Output", (), {"reopen": AsyncMock()})()
+
+        await transport._on_device_change(AudioDeviceSnapshot(1, "mic", "speakers"))
+        await transport._on_device_change(AudioDeviceSnapshot(2, "airpods", "headphones"))
+
+        transport._input.reopen.assert_not_awaited()
+        transport._output.reopen.assert_awaited_once_with()
+
+    async def test_runtime_event_sink_receives_native_device_snapshot(self):
+        sink = AsyncMock()
+        transport = SoundDeviceTransport(SoundDeviceTransportParams(), device_event_sink=sink)
+
+        snapshot = AudioDeviceSnapshot(1, "mic", "speaker")
+        await transport._on_device_change(snapshot)
+
+        sink.assert_awaited_once_with(snapshot)
+
+    async def test_stale_snapshot_cannot_reopen_a_replaced_stream(self):
+        transport = self._transport()
+
+        await transport._on_device_change(AudioDeviceSnapshot(1, "mic", "speaker"))
+        await transport._on_device_change(AudioDeviceSnapshot(3, "airpods", "airpods"))
+        await transport._on_device_change(AudioDeviceSnapshot(2, "mic", "speaker"))
+
+        transport._input.reopen.assert_awaited_once_with()
+        transport._output.reopen.assert_awaited_once_with()
+
+    async def test_failed_input_reopen_keeps_output_route_change_alive(self):
+        transport = self._transport()
+        transport._input.reopen.side_effect = OSError("device unavailable")
+
+        await transport._on_device_change(AudioDeviceSnapshot(1, "mic", "speaker"))
+        await transport._on_device_change(AudioDeviceSnapshot(2, "airpods", "airpods"))
+
+        transport._input.reopen.assert_awaited_once_with()
+        transport._output.reopen.assert_awaited_once_with()
+
+    async def test_transport_starts_and_stops_injected_monitor_once(self):
+        monitor = FakeMonitor()
+        transport = SoundDeviceTransport(SoundDeviceTransportParams(), device_monitor=monitor)
+
+        await transport.start_device_monitor()
+        await transport.start_device_monitor()
+        await transport.stop_device_monitor()
+        await transport.stop_device_monitor()
+
+        monitor.start.assert_awaited_once_with(transport._on_device_change)
+        monitor.stop.assert_awaited_once_with()
+
+    async def test_production_transport_installs_macos_monitor_when_defaults_are_unset(self):
+        monitor = FakeMonitor()
+        with (
+            patch("sounddevice_transport.sys.platform", "darwin"),
+            patch("sounddevice_transport.create_macos_audio_monitor", return_value=monitor) as factory,
+        ):
+            transport = SoundDeviceTransport(SoundDeviceTransportParams())
+            await transport.start_device_monitor()
+
+        factory.assert_called_once_with()
+        monitor.start.assert_awaited_once_with(transport._on_device_change)
+
+    async def test_production_input_start_installs_and_cleanup_releases_device_monitor(self):
+        monitor = FakeMonitor()
+        transport = SoundDeviceTransport(
+            SoundDeviceTransportParams(), device_monitor=monitor
+        )
+        input_transport = transport.input()
+
+        class FakeInputStream:
+            device = 0
+
+            def __init__(self, **_kwargs):
+                pass
+
+            def start(self):
+                pass
+
+            def stop(self):
+                pass
+
+            def close(self):
+                pass
+
+        with (
+            patch("sounddevice_transport.sd.RawInputStream", FakeInputStream),
+            patch("sounddevice_transport.sd.query_devices", return_value={"name": "Fake Mic"}),
+        ):
+            await input_transport.start(StartFrame(audio_in_sample_rate=16000))
+            await input_transport.cleanup()
+
+        monitor.start.assert_awaited_once_with(transport._on_device_change)
+        monitor.stop.assert_awaited_once_with()
+
+    async def test_production_input_start_skips_unavailable_monitor_off_macos(self):
+        transport = SoundDeviceTransport(SoundDeviceTransportParams())
+        input_transport = transport.input()
+
+        class FakeInputStream:
+            device = 0
+
+            def __init__(self, **_kwargs):
+                pass
+
+            def start(self):
+                pass
+
+            def stop(self):
+                pass
+
+            def close(self):
+                pass
+
+        with (
+            patch("sounddevice_transport.sys.platform", "linux"),
+            patch("sounddevice_transport.create_macos_audio_monitor") as factory,
+            patch("sounddevice_transport.sd.RawInputStream", FakeInputStream),
+            patch("sounddevice_transport.sd.query_devices", return_value={"name": "Fake Mic"}),
+        ):
+            await input_transport.start(StartFrame(audio_in_sample_rate=16000))
+            await input_transport.cleanup()
+
+        factory.assert_not_called()
+
+    async def test_cleaning_one_side_keeps_monitor_until_last_side_stops(self):
+        monitor = FakeMonitor()
+        transport = SoundDeviceTransport(SoundDeviceTransportParams(), device_monitor=monitor)
+        input_transport = transport.input()
+        output_transport = transport.output()
+
+        await transport.start_device_monitor(input_transport)
+        await transport.start_device_monitor(output_transport)
+        await input_transport.cleanup()
+
+        monitor.stop.assert_not_awaited()
+        await output_transport.cleanup()
+
+        monitor.start.assert_awaited_once_with(transport._on_device_change)
+        monitor.stop.assert_awaited_once_with()
+
+    async def test_failed_runtime_selection_keeps_previous_pin(self):
+        transport = self._transport(output_device=5)
+        transport._output.reopen.side_effect = OSError("unavailable")
+        with patch("sounddevice_transport.sd.query_devices", return_value=[
+            {"name": "MacBook Air Speakers", "max_input_channels": 0, "max_output_channels": 2},
+            {"name": "AirPods", "max_input_channels": 0, "max_output_channels": 2},
+        ]):
+            with self.assertRaises(OSError):
+                await transport.set_runtime_device("output", "airpods")
+
+        self.assertEqual(transport._params.output_device, 5)
+
+    async def test_runtime_selection_pins_only_requested_direction(self):
+        transport = self._transport()
+        with patch("sounddevice_transport.sd.query_devices", return_value=[
+            {"name": "MacBook Air Speakers", "max_input_channels": 0, "max_output_channels": 2},
+            {"name": "AirPods", "max_input_channels": 1, "max_output_channels": 0},
+            {"name": "AirPods", "max_input_channels": 0, "max_output_channels": 2},
+        ]):
+            result = await transport.set_runtime_device("output", "airpods")
+
+        self.assertEqual(result["device"], 2)
+        self.assertEqual(transport._params.output_device, 2)
+        self.assertIsNone(transport._params.input_device)
+        transport._output.reopen.assert_awaited_once_with(device=2)
+        transport._input.reopen.assert_not_awaited()
+
+    async def test_switching_a_pinned_side_to_default_starts_monitor_for_snapshot(self):
+        monitor = FakeMonitor()
+
+        async def publish_initial_snapshot(callback):
+            await callback(AudioDeviceSnapshot(1, "mic", "speaker"))
+
+        monitor.start.side_effect = publish_initial_snapshot
+        transport = SoundDeviceTransport(
+            SoundDeviceTransportParams(input_device="USB Mic", output_device="USB Speakers"),
+            device_monitor=monitor,
+        )
+        transport._input = type("Input", (), {"reopen": AsyncMock()})()
+
+        await transport.set_runtime_device("input", None)
+
+        monitor.start.assert_awaited_once_with(transport._on_device_change)
+        transport._input.reopen.assert_awaited_once_with()
+
+    async def test_old_input_callback_cannot_deliver_after_replacement(self):
+        input_transport = SoundDeviceInputTransport(SoundDeviceTransportParams())
+        input_transport.push_audio_frame = AsyncMock()
+        input_transport._stream_generation = 2
+
+        await input_transport._push_audio_frame_if_current(1, object())
+
+        input_transport.push_audio_frame.assert_not_awaited()
+
+    async def test_failed_output_stream_start_closes_partial_stream(self):
+        class FailingStream:
+            closed = False
+
+            def __init__(self, **_kwargs):
+                pass
+
+            def start(self):
+                raise OSError("unavailable")
+
+            def close(self):
+                self.closed = True
+
+        output = SoundDeviceOutputTransport(SoundDeviceTransportParams())
+        output._sample_rate = 24000
+        with patch("sounddevice_transport.sd.RawOutputStream", FailingStream):
+            with self.assertRaises(OSError):
+                await output._open_stream()
+
+        self.assertIsNone(output._out_stream)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/web_server.py b/web_server.py
index 5808c68..3287ded 100644
--- a/web_server.py
+++ b/web_server.py
@@ -25,18 +25,21 @@ _sse_clients: Set[asyncio.Queue] = set()
 _workspace_dir: Path = Path(__file__).parent.resolve()
 _model_manager = None
 _voice_manager = None
+_audio_controller = None
 _input_callback: Callable = None
 _recent_events: list = []
 _MAX_HISTORY_EVENTS = 200
 
 
-def set_managers(workspace: Path, model_mgr=None, voice_mgr=None, input_callback=None):
-    global _workspace_dir, _model_manager, _voice_manager, _input_callback
+def set_managers(workspace: Path, model_mgr=None, voice_mgr=None, input_callback=None, audio_controller=None):
+    global _workspace_dir, _model_manager, _voice_manager, _input_callback, _audio_controller
     _workspace_dir = Path(workspace)
     _model_manager = model_mgr
     _voice_manager = voice_mgr
     if input_callback is not None:
         _input_callback = input_callback
+    if audio_controller is not None:
+        _audio_controller = audio_controller
 
 
 def broadcast_event(event_type: str, payload: dict):
@@ -185,6 +188,43 @@ async def handle_set_voice(request):
         return web.json_response({"error": str(e)}, status=500)
 
 
+async def handle_reset_session(request):
+    try:
+        from bin.session_tool import reset_session
+        ok, msg = reset_session(_workspace_dir)
+        if ok:
+            broadcast_event("session_reset", {"message": msg})
+            return web.json_response({"success": True, "message": msg})
+        return web.json_response({"error": msg}, status=500)
+    except Exception as e:
+        return web.json_response({"error": str(e)}, status=500)
+
+
+async def handle_get_audio_devices(request):
+    if not _audio_controller:
+        return web.json_response({"error": "Audio controller not active"}, status=503)
+    return web.json_response({"devices": _audio_controller.available_devices()})
+
+
+async def handle_set_audio_device(request):
+    try:
+        if not _audio_controller:
+            return web.json_response({"error": "Audio controller not active"}, status=503)
+        body = await request.json()
+        direction, device = body.get("direction"), body.get("device")
+        if direction not in {"input", "output"}:
+            return web.json_response({"error": "direction must be input or output"}, status=400)
+        result = await _audio_controller.set_runtime_device(direction, device)
+        broadcast_event("audio_device_selected", result)
+        return web.json_response({"success": True, **result})
+    except (ValueError, RuntimeError) as exc:
+        logger.warning(f"Runtime audio-device selection failed: {exc}")
+        return web.json_response({"error": str(exc)}, status=400)
+    except Exception as exc:
+        logger.exception("Runtime audio-device selection failed")
+        return web.json_response({"error": str(exc)}, status=500)
+
+
 async def handle_show_file_api(request):
     try:
         body = await request.json()
@@ -249,9 +289,12 @@ async def start_server(workspace: Path, host: str = "127.0.0.1", port: int = 888
     app.router.add_get("/api/models", handle_get_models)
     app.router.add_post("/api/model", handle_set_model)
     app.router.add_post("/api/voice", handle_set_voice)
+    app.router.add_get("/api/audio-devices", handle_get_audio_devices)
+    app.router.add_post("/api/audio-device", handle_set_audio_device)
     app.router.add_post("/api/show_file", handle_show_file_api)
     app.router.add_post("/api/open_browser", handle_open_browser_api)
     app.router.add_post("/api/send", handle_send_message_api)
+    app.router.add_post("/api/session/reset", handle_reset_session)
 
     runner = web.AppRunner(app)
     await runner.setup()
@@ -692,6 +735,9 @@ HTML_INDEX = """<!DOCTYPE html>
                     <div class="pill" id="voicePill" onclick="openVoiceModal()">
                         Voice: <strong id="voiceName">Loading...</strong>
                     </div>
+                    <div class="pill" id="resetPill" onclick="resetSession()" title="Start a fresh conversation session">
+                        🔄 <strong>Reset Session</strong>
+                    </div>
                 </div>
             </header>
 
@@ -843,6 +889,21 @@ HTML_INDEX = """<!DOCTYPE html>
             .catch(err => console.error('Failed to send message:', err));
         }
 
+        async function resetSession() {
+            if (!confirm('Start a fresh Hermes conversation session?')) return;
+            try {
+                const res = await fetch('/api/session/reset', { method: 'POST' });
+                const data = await res.json();
+                if (data.success) {
+                    appendToolStep('System', data.message || 'Session reset.');
+                } else {
+                    alert('Failed to reset session: ' + (data.error || 'Unknown error'));
+                }
+            } catch (err) {
+                alert('Error resetting session: ' + err.message);
+            }
+        }
+
         function handleKeyDown(e) {
             if (e.key === 'Enter') {
                 sendMessage();