Let python-dotenv be the only reader of .env

.env.example

@@ -1,3 +1,9 @@
+# Syntax: KEY=value, one per line. Values are taken literally to end of line,
+# so do NOT add trailing comments after a value. Quote anything containing
+# spaces. Lines starting with # are ignored.
+#
+# This file is read only by the bot (python-dotenv); systemd does not parse it.
+
 # ── Discord ────────────────────────────────────────────────────────────
 # Required. Bot token from https://discord.com/developers/applications
 DISCORD_TOKEN=

config.py

@@ -9,7 +9,16 @@
 
 from dotenv import load_dotenv
 
-load_dotenv()
+# python-dotenv is the single owner of .env — the systemd unit deliberately does
+# not set EnvironmentFile, because the two parsers disagree about quoting and
+# inline comments, and a value they disagree on fails silently and looks like a
+# bad credential.
+#
+# The path is anchored to the project root rather than left to search upward
+# from the working directory, so the same file is picked up whether the bot is
+# started by systemd, from a shell anywhere, or by the test runner.
+PROJECT_ROOT = os.path.dirname(os.path.abspath(__file__))
+load_dotenv(os.path.join(PROJECT_ROOT, ".env"))
 
 # ── Bot ───────────────────────────────────────────────────────────────
 DISCORD_TOKEN  = os.getenv("DISCORD_TOKEN")
@@ -70,9 +79,9 @@ def runtime_versions() -> dict:
     deployed without git, or without FFmpeg on PATH, should still start and say
     so plainly.
     """
-    root = os.path.dirname(os.path.abspath(__file__))
     return {
-        "commit": _first_line(["git", "rev-parse", "--short", "HEAD"], cwd=root) or "unknown",
+        "commit": _first_line(
+            ["git", "rev-parse", "--short", "HEAD"], cwd=PROJECT_ROOT) or "unknown",
         "yt_dlp": _first_line([sys.executable, "-m", "yt_dlp", "--version"]) or "unknown",
         "ffmpeg": _ffmpeg_version(),
         "python": platform.python_version(),

deploy/setup.sh

@@ -75,7 +75,10 @@ Wants=network-online.target
 Type=simple
 User=$APP_USER
 WorkingDirectory=$APP_DIR
-EnvironmentFile=$APP_DIR/.env
+# No EnvironmentFile on purpose. The bot reads .env with python-dotenv, and
+# having systemd parse the same file too means two parsers with different rules
+# for quoting and inline comments — they disagree silently, and the result looks
+# like a bad credential rather than a parsing problem.
 # Keep caches inside the (writable) app dir since HOME is read-only below.
 Environment=XDG_CACHE_HOME=$APP_DIR/.cache
 Environment=DENO_DIR=$APP_DIR/.cache/deno

tests/test_config.py

@@ -135,3 +135,30 @@ def test_log_runtime_leaks_no_secrets(caplog, monkeypatch):
     with caplog.at_level("INFO", logger="loopify"):
         config.log_runtime()
     assert "super-secret-token-value" not in caplog.text
+
+
+# -- .env ownership ----------------------------------------------------
+
+def test_dotenv_is_anchored_to_the_project_root():
+    """
+    Searching upward from the working directory would pick up a different .env
+    depending on where the bot was started from.
+    """
+    import os
+    assert os.path.isfile(os.path.join(config.PROJECT_ROOT, "config.py"))
+
+
+def test_the_systemd_unit_does_not_also_parse_env():
+    """
+    Two parsers over one file disagree on quoting and fail silently. Only
+    python-dotenv reads .env; the unit must not declare EnvironmentFile.
+    """
+    import os
+    setup = os.path.join(config.PROJECT_ROOT, "deploy", "setup.sh")
+    with open(setup, encoding="utf-8") as handle:
+        body = handle.read()
+    active = [
+        line for line in body.splitlines()
+        if "EnvironmentFile" in line and not line.lstrip().startswith("#")
+    ]
+    assert active == []