install.sh: create venv and install dependencies

Creates .venv/ with python3 -m venv if not present, then installs/
updates requirements.txt into it before setting up the systemd service.
The service ExecStart always uses the venv Python.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

install.sh

@@ -22,20 +22,29 @@ SYSTEMD_DIR="$HOME/.config/systemd/user"
 SERVICE_FILE="$SYSTEMD_DIR/$SERVICE_NAME.service"
 LOG_DIR="$SCRIPT_DIR/logs"
 
-# Prefer project venv, fall back to system python3
-if [[ -x "$SCRIPT_DIR/.venv/bin/python" ]]; then
-    PYTHON="$SCRIPT_DIR/.venv/bin/python"
-else
-    PYTHON="$(command -v python3)"
-fi
+VENV="$SCRIPT_DIR/.venv"
+PYTHON="$VENV/bin/python"
 
 echo "==> we_monitor installer"
 echo "    Project : $SCRIPT_DIR"
-echo "    Python  : $PYTHON"
 echo "    User    : $USER"
 echo ""
 
-# ── 1. credentials template ───────────────────────────────────────────────────
+# ── 1. virtual environment ────────────────────────────────────────────────────
+if [[ ! -x "$PYTHON" ]]; then
+    echo "==> Creating virtual environment : $VENV"
+    python3 -m venv "$VENV"
+else
+    echo "==> Virtual environment exists   : $VENV"
+fi
+
+echo "==> Installing / updating dependencies"
+"$VENV/bin/pip" install --quiet --upgrade pip
+"$VENV/bin/pip" install --quiet -r "$SCRIPT_DIR/requirements.txt"
+echo "    Python  : $PYTHON"
+echo ""
+
+# ── 2. credentials template ───────────────────────────────────────────────────
 mkdir -p "$CREDS_DIR"
 chmod 700 "$CREDS_DIR"
 
@@ -55,11 +64,11 @@ else
     echo "==> Credentials file exists      : $CREDS_FILE"
 fi
 
-# ── 2. log directory ──────────────────────────────────────────────────────────
+# ── 3. log directory ──────────────────────────────────────────────────────────
 mkdir -p "$LOG_DIR"
 echo "==> Log directory                : $LOG_DIR"
 
-# ── 3. systemd user service ───────────────────────────────────────────────────
+# ── 4. systemd user service ───────────────────────────────────────────────────
 mkdir -p "$SYSTEMD_DIR"
 
 cat > "$SERVICE_FILE" <<EOF
@@ -84,7 +93,7 @@ EOF
 
 echo "==> Installed service unit       : $SERVICE_FILE"
 
-# ── 4. enable linger (service survives logout / starts at boot) ───────────────
+# ── 5. enable linger (service survives logout / starts at boot) ───────────────
 if loginctl enable-linger "$USER" 2>/dev/null; then
     echo "==> Linger enabled for $USER (service starts at boot)"
 else
@@ -92,7 +101,7 @@ else
     echo "    Run as root to fix: loginctl enable-linger $USER"
 fi
 
-# ── 5. reload and enable (but do NOT start yet) ───────────────────────────────
+# ── 6. reload and enable (but do NOT start yet) ───────────────────────────────
 systemctl --user daemon-reload
 systemctl --user enable "$SERVICE_NAME"