android-test: headless emulator default for GUI smokes

Default EMULATOR_HEADLESS=1 (-no-window, QT offscreen) while guest GLES
still runs via SwiftShader. Auto-start AVD when no adb device; WINDOWED=1
for a host window on laptops.

scripts/taler-monitoring/GIT-AUTOMATION-NOTES.md

@@ -156,12 +156,12 @@ STACK=stage ./android-test/run-android-pay-smoke.sh
 **User-local emulator (no apt root if SDK already under `$HOME/Android/Sdk`):**
 
 ```bash
-export ANDROID_HOME=$HOME/Android/Sdk
+# Default = headless (no host window); guest GLES via SwiftShader.
-export PATH=$ANDROID_HOME/emulator:$ANDROID_HOME/platform-tools:$PATH
+# Prefer the helper — same flags smokes use:
-# AVD e.g. TalerWallet34 (google_apis x86_64)
+./android-test/start-android-emulator.sh --wait
-emulator -avd TalerWallet34 -no-window -gpu swiftshader_indirect -memory 1536 &
-adb wait-for-device
 ./android-test/run-android-pay-smoke.sh
+# Or let smoke auto-start the AVD (AUTO_START_EMULATOR=1).
+# Windowed laptop: WINDOWED=1 ./android-test/start-android-emulator.sh --wait
 ```
 
 **Limits (clementine 2026-07-17):** host RAM ~3.7 GiB → emulator often ANRs System UI;

scripts/taler-monitoring/android-test/GUI-AUTOMATION-NOTES.md

@@ -120,6 +120,39 @@ Automation can run on hosts that support **Android only**, **GUI tooling only**
 | `AUTO_ANDROID` | `0` / `1` | Run Android wallet automation (adb, APK, emulator/device) |
 | `AUTO_GUI` | `0` / `1` | Drive **graphical** UI (uiautomator taps, multi-round). If `0`, deep-link/CLI-only install smoke. |
 | `AUTO_PLATFORM` | `auto` / `linux` / `macos` / `ios` | Host family (optional override) |
+| `EMULATOR_HEADLESS` | **`1` (default)** / `0` | No host window (`-no-window`). Server/CI-safe. |
+| `WINDOWED` | `0` / `1` | Shortcut: `WINDOWED=1` ⇒ show emulator window (`EMULATOR_HEADLESS=0`) |
+| `EMULATOR_GPU` | default **`swiftshader_indirect`** | Guest GLES still runs headless (layout/taps/screenshots). Override `host` only if windowed + real GPU. |
+| `AUTO_START_EMULATOR` | **`1` (default)** / `0` | If no adb device, start AVD via `start-android-emulator.sh --wait` |
+
+---
+
+## Headless mode (default)
+
+**Default for all GUI / pay smokes:** no window on the host. Opening an emulator
+GUI on servers (or headless CI) is wrong; these scripts therefore start the AVD
+with **`-no-window`** and still keep **graphics logic** in the guest:
+
+| Piece | Headless default |
+|-------|------------------|
+| Host window | **off** (`-no-window`, `QT_QPA_PLATFORM=offscreen`, no `DISPLAY`) |
+| Guest GLES | **on** via **SwiftShader** (`-gpu swiftshader_indirect`) |
+| UI automation | **on** — `uiautomator` dump/tap + `screencap` (no X11 needed) |
+| Audio / boot anim | off (`-no-audio -no-boot-anim`) |
+
+```bash
+# explicit (same as default)
+./start-android-emulator.sh --wait
+
+# or let smoke auto-start headless AVD when no phone is plugged in
+STACK=goa ./run-android-gui-smoke.sh
+
+# laptop: show the emulator window
+WINDOWED=1 ./start-android-emulator.sh --wait
+# or: EMULATOR_HEADLESS=0 EMULATOR_GPU=host ./start-android-emulator.sh --wait
+```
+
+Shared code: `lib_android_env.sh` + `start-android-emulator.sh`.
 
 **Semantics:**
 
@@ -203,6 +236,8 @@ Scripts **today** implement Android only; they should honour:
 | `run-android-gui-smoke.sh` | Multi-round GUI drive |
 | `run-goa-gui-chain.sh` | Multi mint/withdraw/pay (gui-workflows port) |
 | `run-android-build-and-smoke.sh` | Build inference fix branch + smoke (`GUI=1` optional) |
+| `start-android-emulator.sh` | Start AVD (**headless default**, SwiftShader) |
+| `lib_android_env.sh` | Flags, PATH, `android_ensure_device` |
 | `lib_ui.py` | Dump/tap/ANR helpers |
 
 ---
@@ -233,6 +268,7 @@ Scripts **today** implement Android only; they should honour:
 - [x] Minimalvariante: was geht / was nicht (Beschränkungen)  
 - [x] Two stacks (goa / stage)  
 - [x] Flags design (`AUTO_ANDROID` / `AUTO_GUI` / platform defaults)  
+- [x] **Headless emulator default** (`EMULATOR_HEADLESS=1`, SwiftShader)  
 - [x] Linux default = Android suite only  
 - [x] Inference-branch policy  
 - [ ] Wrapper enforces flags in every entry script (incremental)  

scripts/taler-monitoring/android-test/README.md

@@ -59,5 +59,16 @@ Canonical notes (minimal variant, **flags**, Linux defaults):
 | `AUTO_ANDROID` | `1` | Run Android adb/APK automation |
 | `AUTO_GUI` | `1` | Graphical uiautomator drive (else deep-link only) |
 | `AUTO_PLATFORM` | `auto` → `linux` | Host family; macOS can later pair with iOS out of tree |
+| **`EMULATOR_HEADLESS`** | **`1`** | **No host window** (`-no-window`). Server-safe. |
+| `EMULATOR_GPU` | `swiftshader_indirect` | Guest GLES still active for UI/taps/screenshots |
+| `AUTO_START_EMULATOR` | `1` | Auto-start headless AVD if no adb device |
+| `WINDOWED` | `0` | `WINDOWED=1` → show emulator window |
+
+```bash
+# headless AVD only (default path for servers)
+./start-android-emulator.sh --wait
+# windowed (laptops)
+WINDOWED=1 ./start-android-emulator.sh --wait
+```
 
 See also parent [GIT-AUTOMATION-NOTES.md](../GIT-AUTOMATION-NOTES.md).

scripts/taler-monitoring/android-test/lib_android_env.sh

@@ -0,0 +1,153 @@
+# shellcheck shell=bash
+# Shared Android env for GUI / adb smokes.
+# Source:  . "$ROOT/lib_android_env.sh"
+#
+# Defaults favour **servers / CI**: no host window (headless emulator), while the
+# guest still runs GLES via SwiftShader so UI layout / uiautomator work.
+#
+# See GUI-AUTOMATION-NOTES.md → Headless mode
+
+# --- SDK / PATH ---------------------------------------------------------------
+export ANDROID_HOME="${ANDROID_HOME:-${ANDROID_SDK_ROOT:-$HOME/Android/Sdk}}"
+export ANDROID_SDK_ROOT="${ANDROID_SDK_ROOT:-$ANDROID_HOME}"
+for d in \
+  "$ANDROID_HOME/platform-tools" \
+  "$ANDROID_HOME/emulator" \
+  "$ANDROID_HOME/cmdline-tools/latest/bin"
+do
+  [ -d "$d" ] && case ":$PATH:" in *":$d:"*) ;; *) PATH="$d:$PATH" ;; esac
+done
+export PATH
+
+# AVD path (some hosts keep AVDs under ~/.config/.android)
+if [ -z "${ANDROID_AVD_HOME:-}" ]; then
+  if [ -d "$HOME/.android/avd" ]; then
+    export ANDROID_AVD_HOME="$HOME/.android/avd"
+  elif [ -d "$HOME/.config/.android/avd" ]; then
+    export ANDROID_AVD_HOME="$HOME/.config/.android/avd"
+    # emulator also looks at ~/.android/avd — soft-link if missing
+    if [ ! -e "$HOME/.android/avd" ]; then
+      mkdir -p "$HOME/.android"
+      ln -sfn "$HOME/.config/.android/avd" "$HOME/.android/avd" 2>/dev/null || true
+    fi
+  fi
+fi
+
+# --- Platform / feature flags -------------------------------------------------
+os=$(uname -s)
+case "${AUTO_PLATFORM:-auto}" in
+  auto)
+    case "$os" in
+      Linux)  : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
+      Darwin) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
+      *)      : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;;
+    esac
+    ;;
+  linux|macos) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
+  *)           : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;;
+esac
+
+# Headless = default (no X11/Wayland window on host). GUI *logic* still runs in
+# the guest via software GPU. Set EMULATOR_HEADLESS=0 or WINDOWED=1 for a window.
+: "${EMULATOR_HEADLESS:=1}"
+if [ "${WINDOWED:-0}" = "1" ]; then
+  EMULATOR_HEADLESS=0
+fi
+export EMULATOR_HEADLESS
+
+# Soft GLES for headless; windowed may override to host/auto if set by user.
+if [ "${EMULATOR_HEADLESS}" = "1" ]; then
+  : "${EMULATOR_GPU:=swiftshader_indirect}"
+else
+  : "${EMULATOR_GPU:=swiftshader_indirect}"  # still safe default; host GPU: EMULATOR_GPU=host
+fi
+export EMULATOR_GPU
+
+: "${EMULATOR_AVD:=TalerWallet34}"
+: "${EMULATOR_MEMORY:=1536}"
+: "${EMULATOR_CORES:=2}"
+# If no adb device: start headless AVD (0 = require phone/manual emulator)
+: "${AUTO_START_EMULATOR:=1}"
+: "${EMULATOR_BOOT_TIMEOUT:=180}"
+: "${EMULATOR_LOG:=/tmp/taler-android-emulator.log}"
+
+android_adb_serial() {
+  adb devices 2>/dev/null | awk '/\tdevice$/{print $1; exit}'
+}
+
+android_has_device() {
+  [ -n "$(android_adb_serial)" ]
+}
+
+# Build emulator argv for current headless/windowed mode.
+# Prints args; caller exec/nohup.
+android_emulator_args() {
+  local avd="${1:-$EMULATOR_AVD}"
+  local args=( -avd "$avd" -gpu "$EMULATOR_GPU" -no-audio -no-boot-anim )
+  if [ "${EMULATOR_HEADLESS}" = "1" ]; then
+    args+=( -no-window )
+    # Avoid Qt trying to open a display on servers
+    export QT_QPA_PLATFORM="${QT_QPA_PLATFORM:-offscreen}"
+  fi
+  if [ -n "${EMULATOR_MEMORY:-}" ]; then
+    args+=( -memory "$EMULATOR_MEMORY" )
+  fi
+  if [ -n "${EMULATOR_CORES:-}" ]; then
+    args+=( -cores "$EMULATOR_CORES" )
+  fi
+  # extra user flags
+  # shellcheck disable=SC2206
+  if [ -n "${EMULATOR_EXTRA_ARGS:-}" ]; then
+    # intentional word-split for extra flags
+    args+=( ${EMULATOR_EXTRA_ARGS} )
+  fi
+  printf '%s\n' "${args[@]}"
+}
+
+# Ensure an adb "device" is online. Optionally start headless emulator.
+# Sets SERIAL / ANDROID_SERIAL on success. Returns 0 ok, 3 no device.
+android_ensure_device() {
+  local serial
+  serial="${SERIAL:-${ANDROID_SERIAL:-}}"
+  if [ -z "$serial" ]; then
+    serial=$(android_adb_serial || true)
+  fi
+  if [ -n "$serial" ]; then
+    SERIAL="$serial"
+    export ANDROID_SERIAL="$serial"
+    return 0
+  fi
+
+  if [ "${AUTO_START_EMULATOR}" != "1" ]; then
+    echo "no adb device (AUTO_START_EMULATOR=0 — plug phone or start AVD manually)" >&2
+    return 3
+  fi
+
+  if ! command -v emulator >/dev/null 2>&1; then
+    echo "no adb device and emulator binary missing under $ANDROID_HOME" >&2
+    return 3
+  fi
+
+  echo "no adb device → starting AVD ${EMULATOR_AVD} (headless=${EMULATOR_HEADLESS} gpu=${EMULATOR_GPU})"
+  local starter
+  starter="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/start-android-emulator.sh"
+  if [ ! -x "$starter" ]; then
+    echo "missing $starter" >&2
+    return 3
+  fi
+  EMULATOR_HEADLESS="$EMULATOR_HEADLESS" EMULATOR_GPU="$EMULATOR_GPU" \
+    EMULATOR_AVD="$EMULATOR_AVD" EMULATOR_MEMORY="$EMULATOR_MEMORY" \
+    EMULATOR_CORES="$EMULATOR_CORES" EMULATOR_LOG="$EMULATOR_LOG" \
+    EMULATOR_BOOT_TIMEOUT="$EMULATOR_BOOT_TIMEOUT" \
+    "$starter" --wait || return 3
+
+  serial=$(android_adb_serial || true)
+  if [ -z "$serial" ]; then
+    echo "emulator started but no adb device yet — see $EMULATOR_LOG" >&2
+    return 3
+  fi
+  SERIAL="$serial"
+  export ANDROID_SERIAL="$serial"
+  echo "device: $SERIAL (headless=${EMULATOR_HEADLESS})"
+  return 0
+}

scripts/taler-monitoring/android-test/run-android-gui-smoke.sh

@@ -12,14 +12,9 @@
 #
 set -euo pipefail
 ROOT=$(cd "$(dirname "$0")" && pwd)
+# shellcheck source=lib_android_env.sh
+. "$ROOT/lib_android_env.sh"
 
-# Platform flags (GUI-AUTOMATION-NOTES.md). Linux → Android only.
-os=$(uname -s)
-case "${AUTO_PLATFORM:-auto}" in
-  auto) case "$os" in Linux|Darwin) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;; *) : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;; esac ;;
-  linux|macos) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
-  *) : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;;
-esac
 [ "${AUTO_ANDROID}" = "1" ] || { echo "skipped: AUTO_ANDROID=${AUTO_ANDROID}"; exit 0; }
 if [ "${AUTO_GUI}" != "1" ]; then
   echo "AUTO_GUI=0 → deep-link smoke only"
@@ -46,17 +41,12 @@ STACK="${STACK:-auto}"
 SERIAL="${SERIAL:-}"
 mkdir -p "$OUT_DIR"
 
-if ! command -v adb >/dev/null 2>&1; then
-  [ -x "$HOME/Android/Sdk/platform-tools/adb" ] && export PATH="$HOME/Android/Sdk/platform-tools:$PATH"
-fi
 command -v adb >/dev/null || { echo "adb missing" >&2; exit 2; }
 
-if [ -z "$SERIAL" ]; then
+# Headless default: no host window; guest GLES via SwiftShader (uiautomator).
-  SERIAL=$(adb devices | awk '/\tdevice$/{print $1; exit}')
+android_ensure_device || { echo "no adb device (try ./start-android-emulator.sh --wait)" >&2; exit 3; }
-fi
-[ -n "$SERIAL" ] || { echo "no adb device" >&2; exit 3; }
 ADB=(adb -s "$SERIAL")
-echo "device: $SERIAL  mode: GUI (uiautomator)"
+echo "device: $SERIAL  mode: GUI (uiautomator) headless=${EMULATOR_HEADLESS} gpu=${EMULATOR_GPU}"
 
 case "$STACK" in
   auto)

scripts/taler-monitoring/android-test/run-android-pay-smoke.sh

@@ -20,15 +20,9 @@
 #
 set -euo pipefail
 ROOT=$(cd "$(dirname "$0")" && pwd)
+# shellcheck source=lib_android_env.sh
+. "$ROOT/lib_android_env.sh"
 
-# Platform flags (see GUI-AUTOMATION-NOTES.md). Linux default: Android only.
-os=$(uname -s)
-case "${AUTO_PLATFORM:-auto}" in
-  auto) case "$os" in Linux) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;; Darwin) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;; *) : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;; esac ;;
-  linux) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
-  macos) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
-  *) : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;;
-esac
 if [ "${AUTO_ANDROID}" != "1" ]; then
   echo "skipped: AUTO_ANDROID=${AUTO_ANDROID} (platform flags — see GUI-AUTOMATION-NOTES.md)"
   exit 0
@@ -46,28 +40,23 @@ OUT_DIR="${OUT_DIR:-$ROOT/out}"
 mkdir -p "$APK_DIR" "$OUT_DIR"
 
 if ! command -v adb >/dev/null 2>&1; then
-  if [ -x "$HOME/Android/Sdk/platform-tools/adb" ]; then
+  echo "adb missing — install android-tools-adb or user SDK platform-tools" >&2
-    export PATH="$HOME/Android/Sdk/platform-tools:$PATH"
+  exit 2
-  else
-    echo "adb missing — install android-tools-adb or user SDK platform-tools" >&2
-    exit 2
-  fi
 fi
 
-if [ -z "$SERIAL" ]; then
+# Default: headless AVD (no host window). WINDOWED=1 / EMULATOR_HEADLESS=0 for UI.
-  SERIAL=$(adb devices | awk '/\tdevice$/{print $1; exit}')
+if ! android_ensure_device; then
-fi
+  cat >&2 <<EOF
-if [ -z "$SERIAL" ]; then
+No adb device. Options:
-  cat >&2 <<'EOF'
-No adb device. Options (no root for user-local emulator if /dev/kvm is usable):
   1) Plug phone with USB debugging
-  2) Start AVD:  $HOME/Android/Sdk/emulator/emulator -avd TalerWallet34 -no-window
+  2) Headless AVD (default):  $ROOT/start-android-emulator.sh --wait
-  3) Then re-run this script
+  3) Windowed AVD:            WINDOWED=1 $ROOT/start-android-emulator.sh --wait
+  4) AUTO_START_EMULATOR=0 disables auto-start from this smoke
 EOF
   exit 3
 fi
 ADB=(adb -s "$SERIAL")
-echo "device: $SERIAL"
+echo "device: $SERIAL  emulator_headless=${EMULATOR_HEADLESS} gpu=${EMULATOR_GPU}"
 
 # Resolve stack endpoints
 case "$STACK" in

scripts/taler-monitoring/android-test/run-goa-gui-chain.sh

@@ -37,19 +37,12 @@ step() { echo; echo "======== $* ========"; }
 info() { echo "  $*"; }
 pause() { sleep "${1:-${PAUSE:-0.8}}"; }
 
-# Platform flags — Linux default Android+GUI (see GUI-AUTOMATION-NOTES.md)
+# Platform flags + headless emulator defaults (see GUI-AUTOMATION-NOTES.md)
-os=$(uname -s)
+# shellcheck source=lib_android_env.sh
-case "${AUTO_PLATFORM:-auto}" in
+. "$ROOT/lib_android_env.sh"
-  auto) case "$os" in Linux|Darwin) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;; *) : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;; esac ;;
-  linux|macos) : "${AUTO_ANDROID:=1}"; : "${AUTO_GUI:=1}" ;;
-  *) : "${AUTO_ANDROID:=0}"; : "${AUTO_GUI:=0}" ;;
-esac
 [ "${AUTO_ANDROID}" = "1" ] || { echo "skipped: AUTO_ANDROID=${AUTO_ANDROID}"; exit 0; }
 [ "${AUTO_GUI}" = "1" ] || { echo "skipped: AUTO_GUI=${AUTO_GUI} (chain is GUI)"; exit 0; }
 
-if ! command -v adb >/dev/null 2>&1; then
-  [ -x "$HOME/Android/Sdk/platform-tools/adb" ] && export PATH="$HOME/Android/Sdk/platform-tools:$PATH"
-fi
 command -v adb >/dev/null || die "adb not found"
 command -v python3 >/dev/null || die "python3 required"
 
@@ -112,12 +105,11 @@ if [[ ! -f "${EXP_PW_FILE:-}" && "$STACK" = "stage" ]]; then
 fi
 [[ -n "${EXP_PW_FILE:-}" && -f "$EXP_PW_FILE" ]] || die "set EXP_PW_FILE (explorer password)"
 
-if [[ -z "${ANDROID_SERIAL:-}" ]]; then
+# Headless AVD by default (no host window). WINDOWED=1 for a visible emulator.
-  n=$(adb devices | awk 'NR>1 && $2=="device"{c++} END{print c+0}')
+SERIAL="${SERIAL:-${ANDROID_SERIAL:-}}"
-  [[ "$n" -ge 1 ]] || die "no adb device (start emulator or plug phone)"
+android_ensure_device || die "no adb device (./start-android-emulator.sh --wait)"
-  export ANDROID_SERIAL=$(adb devices | awk 'NR>1 && $2=="device"{print $1; exit}')
+export ANDROID_SERIAL="$SERIAL"
-fi
+info "ANDROID_SERIAL=$ANDROID_SERIAL  STACK=$STACK  PKG=$PKG  SHOTDIR=$SHOTDIR  headless=$EMULATOR_HEADLESS gpu=$EMULATOR_GPU"
-info "ANDROID_SERIAL=$ANDROID_SERIAL  STACK=$STACK  PKG=$PKG  SHOTDIR=$SHOTDIR"
 ADB=(adb -s "$ANDROID_SERIAL")
 
 adb_sh() { "${ADB[@]}" shell "$@"; }

scripts/taler-monitoring/android-test/start-android-emulator.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+# Start the Taler Android AVD. **Default = headless** (no host window).
+# Guest GLES still runs via SwiftShader so uiautomator / screenshots work.
+#
+# Usage:
+#   ./start-android-emulator.sh              # headless, background
+#   ./start-android-emulator.sh --wait       # headless + wait for boot
+#   ./start-android-emulator.sh --windowed   # show emulator window
+#   EMULATOR_HEADLESS=0 ./start-android-emulator.sh
+#   EMULATOR_GPU=host WINDOWED=1 ./start-android-emulator.sh
+#
+# Env: EMULATOR_AVD EMULATOR_MEMORY EMULATOR_CORES EMULATOR_GPU
+#      EMULATOR_HEADLESS EMULATOR_LOG EMULATOR_BOOT_TIMEOUT EMULATOR_EXTRA_ARGS
+#
+set -euo pipefail
+ROOT=$(cd "$(dirname "$0")" && pwd)
+# shellcheck source=lib_android_env.sh
+. "$ROOT/lib_android_env.sh"
+
+WAIT=0
+for a in "$@"; do
+  case "$a" in
+    --wait) WAIT=1 ;;
+    --windowed| --gui) EMULATOR_HEADLESS=0; export EMULATOR_HEADLESS ;;
+    --headless) EMULATOR_HEADLESS=1; export EMULATOR_HEADLESS ;;
+    -h|--help)
+      sed -n '2,18p' "$0"
+      exit 0
+      ;;
+  esac
+done
+
+command -v emulator >/dev/null || {
+  echo "emulator not found (ANDROID_HOME=$ANDROID_HOME)" >&2
+  exit 2
+}
+command -v adb >/dev/null || {
+  echo "adb not found" >&2
+  exit 2
+}
+
+# Already booted?
+if serial=$(android_adb_serial); [ -n "$serial" ]; then
+  boot=$(adb -s "$serial" shell getprop sys.boot_completed 2>/dev/null | tr -d '\r' || true)
+  if [ "$boot" = "1" ]; then
+    echo "already running: $serial (boot_completed=1) — headless default still applies to *new* starts"
+    exit 0
+  fi
+fi
+
+# Avoid pkill patterns that match this wrapper's argv (self-kill).
+mapfile -t EMU_ARGS < <(android_emulator_args "$EMULATOR_AVD")
+echo "starting: emulator ${EMU_ARGS[*]}"
+echo "  headless=$EMULATOR_HEADLESS  gpu=$EMULATOR_GPU  log=$EMULATOR_LOG"
+
+if [ "${EMULATOR_HEADLESS}" = "1" ]; then
+  export QT_QPA_PLATFORM="${QT_QPA_PLATFORM:-offscreen}"
+  # Do not require DISPLAY
+  unset DISPLAY || true
+fi
+
+mkdir -p "$(dirname "$EMULATOR_LOG")"
+# Background; do not use pkill -f emulator from callers matching full cmdline
+nohup emulator "${EMU_ARGS[@]}" >"$EMULATOR_LOG" 2>&1 &
+echo "emulator pid=$!  log=$EMULATOR_LOG"
+
+if [ "$WAIT" != "1" ]; then
+  echo "not waiting (pass --wait for boot). adb devices when ready."
+  exit 0
+fi
+
+echo "waiting for boot (timeout ${EMULATOR_BOOT_TIMEOUT}s)…"
+deadline=$((SECONDS + EMULATOR_BOOT_TIMEOUT))
+serial=""
+while (( SECONDS < deadline )); do
+  adb wait-for-device 2>/dev/null || true
+  serial=$(android_adb_serial || true)
+  if [ -n "$serial" ]; then
+    boot=$(adb -s "$serial" shell getprop sys.boot_completed 2>/dev/null | tr -d '\r' || true)
+    if [ "$boot" = "1" ]; then
+      echo "BOOT_OK serial=$serial headless=$EMULATOR_HEADLESS gpu=$EMULATOR_GPU"
+      exit 0
+    fi
+  fi
+  sleep 2
+done
+
+echo "boot timeout — last log:" >&2
+tail -30 "$EMULATOR_LOG" >&2 || true
+exit 3