Update README and run.sh to select PyTorch flavor based on system and environment variables

README.md

@@ -47,6 +47,13 @@ Quick start:
 
 This creates or refreshes `backend/.venv`, installs Python dependencies, installs npm dependencies, and starts the dev stack.
 
+On Linux `x86_64`, `run.sh` now selects a PyTorch flavor before installing `openai-whisper`:
+
+- Steam Deck / SteamOS and other non-NVIDIA Linux hosts default to CPU-only PyTorch, which avoids downloading NVIDIA CUDA runtime wheels that Whisper does not need there.
+- NVIDIA Linux hosts keep the default PyTorch install path.
+- Override with `HEIMGEIST_TORCH_FLAVOR=default`, `HEIMGEIST_TORCH_FLAVOR=cpu`, or `HEIMGEIST_TORCH_FLAVOR=rocm6.4`.
+- Use `HEIMGEIST_TORCH_INDEX_URL=...` if you need a custom PyTorch wheel index.
+
 Manual startup:
 
 ```bash

run.sh

@@ -3,17 +3,132 @@ set -eu
 
 PYTHON_BIN="${PYTHON_BIN:-python3.13}"
 VENV_DIR="backend/.venv"
+TORCH_FLAVOR_FILE="$VENV_DIR/.heimgeist-torch-flavor"
+HEIMGEIST_TORCH_FLAVOR="${HEIMGEIST_TORCH_FLAVOR:-auto}"
+HEIMGEIST_TORCH_INDEX_URL="${HEIMGEIST_TORCH_INDEX_URL:-}"
+
+is_linux_x86_64() {
+  [ "$(uname -s)" = "Linux" ] && [ "$(uname -m)" = "x86_64" ]
+}
+
+has_nvidia_gpu() {
+  if command -v nvidia-smi >/dev/null 2>&1; then
+    return 0
+  fi
+
+  for vendor_file in /sys/class/drm/card*/device/vendor; do
+    [ -r "$vendor_file" ] || continue
+    if grep -qi "0x10de" "$vendor_file"; then
+      return 0
+    fi
+  done
+
+  return 1
+}
+
+is_steam_deck() {
+  if [ -r /etc/os-release ] && grep -Eiq '(^ID=steamos$|^NAME=.*SteamOS|^PRETTY_NAME=.*SteamOS)' /etc/os-release; then
+    return 0
+  fi
+
+  for dmi_file in \
+    /sys/devices/virtual/dmi/id/product_name \
+    /sys/devices/virtual/dmi/id/product_version \
+    /sys/devices/virtual/dmi/id/board_name
+  do
+    [ -r "$dmi_file" ] || continue
+    if grep -Eiq 'steam deck|jupiter|galileo' "$dmi_file"; then
+      return 0
+    fi
+  done
+
+  return 1
+}
+
+resolve_torch_flavor() {
+  case "$HEIMGEIST_TORCH_FLAVOR" in
+    auto)
+      if is_linux_x86_64; then
+        if is_steam_deck; then
+          printf '%s\n' "cpu"
+          return
+        fi
+        if has_nvidia_gpu; then
+          printf '%s\n' "default"
+          return
+        fi
+        printf '%s\n' "cpu"
+        return
+      fi
+      printf '%s\n' "default"
+      ;;
+    default|cpu|cuda|rocm|rocm6.4)
+      printf '%s\n' "%s" "$HEIMGEIST_TORCH_FLAVOR"
+      ;;
+    *)
+      echo "Unsupported HEIMGEIST_TORCH_FLAVOR '$HEIMGEIST_TORCH_FLAVOR'. Use auto, default, cpu, cuda, rocm, or rocm6.4." >&2
+      exit 1
+      ;;
+  esac
+}
+
+install_selected_torch() {
+  torch_flavor="$1"
+
+  if [ -n "$HEIMGEIST_TORCH_INDEX_URL" ]; then
+    echo "Installing PyTorch from custom index: $HEIMGEIST_TORCH_INDEX_URL"
+    "$VENV_DIR/bin/python" -m pip install --upgrade --index-url "$HEIMGEIST_TORCH_INDEX_URL" torch
+    return
+  fi
+
+  case "$torch_flavor" in
+    default|cuda)
+      return
+      ;;
+    cpu)
+      echo "Installing CPU-only PyTorch for Whisper"
+      "$VENV_DIR/bin/python" -m pip install --upgrade --index-url https://download.pytorch.org/whl/cpu torch
+      ;;
+    rocm|rocm6.4)
+      echo "Installing ROCm PyTorch for Whisper"
+      "$VENV_DIR/bin/python" -m pip install --upgrade --index-url https://download.pytorch.org/whl/rocm6.4 torch
+      ;;
+  esac
+}
 
 if ! command -v "$PYTHON_BIN" >/dev/null 2>&1; then
   echo "Python 3.13 is required. Set PYTHON_BIN to a Python 3.13 executable if needed." >&2
   exit 1
 fi
 
+TORCH_FLAVOR="$(resolve_torch_flavor)"
+RECREATE_VENV=0
+
 if [ ! -x "$VENV_DIR/bin/python" ] || ! "$VENV_DIR/bin/python" -c 'import sys; raise SystemExit(0 if sys.version_info[:2] == (3, 13) else 1)'; then
+  RECREATE_VENV=1
+fi
+
+if [ "$RECREATE_VENV" -eq 0 ]; then
+  PREVIOUS_TORCH_FLAVOR=""
+  if [ -r "$TORCH_FLAVOR_FILE" ]; then
+    PREVIOUS_TORCH_FLAVOR="$(cat "$TORCH_FLAVOR_FILE")"
+  fi
+  if [ -n "$PREVIOUS_TORCH_FLAVOR" ] && [ "$PREVIOUS_TORCH_FLAVOR" != "$TORCH_FLAVOR" ]; then
+    RECREATE_VENV=1
+  elif [ -z "$PREVIOUS_TORCH_FLAVOR" ] && [ "$TORCH_FLAVOR" != "default" ]; then
+    RECREATE_VENV=1
+  fi
+fi
+
+if [ "$RECREATE_VENV" -eq 1 ]; then
   rm -rf "$VENV_DIR"
   "$PYTHON_BIN" -m venv "$VENV_DIR"
 fi
 
+printf '%s\n' "$TORCH_FLAVOR" > "$TORCH_FLAVOR_FILE"
+echo "Using PyTorch flavor: $TORCH_FLAVOR"
+"$VENV_DIR/bin/python" -m pip install --upgrade pip
+install_selected_torch "$TORCH_FLAVOR"
 "$VENV_DIR/bin/python" -m pip install -r backend/requirements.txt
 npm install
 npm run dev