Apply conversation bot improvements (proto-improvements)

Diff vs working-copy baseline = exactly this session's bot edits:
- constants.py: env-var config, safe JSON loading, optional-dependency
  guards, env->netrc token resolution, API_SHARED_KEY + service_headers()
- communication_subroutine.py: queue get(timeout) + Empty handling,
  daemon threads, cooperative stop_event, inbound _authorize_request()
- bot.py: single asyncio event loop with cooperative shutdown
- music_functions / radio_commands / librarian_commands: send
  X-Conjurer-Api-Key on internal HTTP calls via service_headers()

Musician runtime data overlay dropped; conjurer_musician/.gitignore now
keeps generated playlists/mp3 out of the repo. The 1+2+3 musician code
port already lives in the base conjurer_musician.

Depends on #9: must merge after restructure/working-copy-root.

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

communication_subroutine.py

@@ -1,17 +1,20 @@
 import json
 import logging
+import os
 import re
 import threading
 import time
 from queue import Empty, Queue
+from typing import Optional
 from urllib import request as urequest
 
-from flask import Flask, jsonify, request
+from flask import Flask, abort, jsonify, request
 from waitress import serve
 
-HOST_ADDRESS = "192.168.1.31"
-PORT_ADDRESS = 5000
-ICECAST_ADDRESS = "http://192.168.1.15:8000"
+HOST_ADDRESS = os.getenv("CONJURER_DISCORD_HOST", "192.168.1.31")
+PORT_ADDRESS = int(os.getenv("CONJURER_DISCORD_PORT", "5000"))
+ICECAST_ADDRESS = os.getenv("CONJURER_ICECAST", "http://192.168.1.15:8000")
+API_KEY = os.getenv("CONJURER_API_KEY")
 OUT_COMM_Q = Queue()
 IN_COMM_Q = Queue()
 SRCHTITLE = re.compile(rb"StreamTitle=\\*(?P<title>[^;]*);").search
@@ -19,6 +22,12 @@ SRCHTITLE = re.compile(rb"StreamTitle=\\*(?P<title>[^;]*);").search
 awaiting_q = []
 incoming_q = Queue()
 app = Flask(__name__)
+
+
+def _authorize_request() -> None:
+    """Reject inbound calls lacking the shared key (no-op if key is unset)."""
+    if API_KEY and request.headers.get("X-Conjurer-Api-Key") != API_KEY:
+        abort(401)
 PREPPED_TRACKS = {
     "requests": "",
     "hit": "",
@@ -53,6 +62,7 @@ class QueryControl:
 
 @app.route("/prepped_tracks", methods=["POST"])
 def log_radio_tracks():
+    _authorize_request()
     app.logger = logging.getLogger("discord")
 
     app.logger.info(request)
@@ -85,6 +95,7 @@ def answer_external_command():
     :return: The function `answer_external_command()` is returning a JSON response with the message
     "SUCCESS".
     """
+    _authorize_request()
     logger = logging.getLogger("discord")
     logger.info(request)
     record = json.loads(request.data)
@@ -129,34 +140,42 @@ def waitress_run():
     serve(app, host=HOST_ADDRESS, port=PORT_ADDRESS)
 
 
-def scan_queue():
+def scan_queue(stop_event: Optional[threading.Event] = None):
     """
     The function `scan_queue` reads data from a queue, logs it, and appends it to another queue.
 
-    :param _logger: The `_logger` parameter is typically an instance of a logging object that is used to
-    record and store log messages. It is commonly used to track the flow of the program, record errors,
-    and provide information for debugging purposes. In this code snippet, the `_logger` object is used
-    to log the
+    A bounded ``get(timeout=1)`` is used instead of a blocking ``get()`` so the
+    worker can observe ``stop_event`` and exit cleanly during shutdown.
+
+    :param stop_event: optional :class:`threading.Event`; when set the loop
+    stops at the next iteration.
     """
     logger = logging.getLogger("discord")
     while True:
-        data = OUT_COMM_Q.get()
+        if stop_event and stop_event.is_set():
+            logger.info("scan_queue: stop requested")
+            break
+        try:
+            data = OUT_COMM_Q.get(timeout=1)
+        except Empty:
+            continue
         logger.info(data)
         awaiting_q.append(data)
 
 
-def scan_incoming():
+def scan_incoming(stop_event: Optional[threading.Event] = None):
     """
     The `scan_incoming` function continuously checks for incoming data, processes it, and logs when data
     is found.
 
-    :param _logger: The `_logger` parameter in the `scan_incoming` function is a logger object that is
-    used to log messages or information during the execution of the function. It is typically used for
-    debugging, monitoring, or tracking the flow of the program. In this case, the `_logger` is being
-    used
+    :param stop_event: optional :class:`threading.Event`; when set the loop
+    stops at the next iteration.
     """
     logger = logging.getLogger("discord")
     while True:
+        if stop_event and stop_event.is_set():
+            logger.info("scan_incoming: stop requested")
+            break
         try:
             answer = incoming_q.get(block=False)
             logger.info("DATA FOUND")
@@ -204,27 +223,45 @@ def id3(url: str) -> dict:
         return tagdata
 
 
-def comm_subroutine():
+def comm_subroutine(stop_event: Optional[threading.Event] = None):
     """
     The `comm_subroutine` function starts multiple threads to run different tasks concurrently.
 
-    :param logger: The `logger` parameter in the `comm_subroutine` function is an instance of a logger
-    object that is used for logging messages at various levels (e.g., debug, info, warning, error). In
-    the provided code snippet, the logger is used to log messages at the "info" level
+    Workers run as daemon threads and honour an optional ``stop_event`` so the
+    bot can shut the communication layer down cleanly instead of blocking
+    forever on ``join()``.
+
+    :param stop_event: optional :class:`threading.Event` shared with the caller
+    to coordinate a cooperative shutdown.
     """
     # logger.setLevel(logging.DEBUG)
     logger = logging.getLogger("discord")
     logger.info("Started comms")
     threads = []
     # threads.append(threading.Thread(target=flask_debug))
-    threads.append(threading.Thread(target=waitress_run))
-    threads.append(threading.Thread(target=scan_queue))
-    threads.append(threading.Thread(target=scan_incoming))
+    threads.append(threading.Thread(target=waitress_run, daemon=True))
+    threads.append(
+        threading.Thread(
+            target=scan_queue, kwargs={"stop_event": stop_event}, daemon=True
+        )
+    )
+    threads.append(
+        threading.Thread(
+            target=scan_incoming, kwargs={"stop_event": stop_event}, daemon=True
+        )
+    )
 
     for worker in threads:
         worker.start()
-    for worker in threads:
-        worker.join()
+
+    try:
+        while any(thread.is_alive() for thread in threads):
+            if stop_event and stop_event.is_set():
+                break
+            time.sleep(0.5)
+    finally:
+        if stop_event:
+            stop_event.set()
 
 
 if __name__ == "__main__":