diff --git a/AGENTS.md b/AGENTS.md
index 87dc4af..7c5782e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -225,16 +225,19 @@ first if a remote spawn ever mangles an argument.
   The emulator app reaches it at `https://10.0.2.2:8443`; enroll it with
   `adb -s "$SERIAL" shell "am start -a android.intent.action.VIEW -d 'aiapp://enroll?host=10.0.2.2&port=8443&token=…'"`
   (quote so the device shell doesn't eat the `&`s).
-- **Name the device on every `adb` call.** This checkout runs its own
-  emulator — `run-android.sh` derives the AVD name from the directory, so
-  a second clone gets a second AVD rather than queueing for one shared
-  machine-wide `tdep`. With more than one attached, a bare `adb shell` or
-  `adb get-state` fails with `more than one device/emulator` and a bare
-  `adb shell pm list packages` comes back **empty**, which reads as the app
-  having been uninstalled rather than as the question being ambiguous.
-  Get the serial the way `run-android.sh` does — match `adb -s <serial> emu
-  avd name` against the AVD — or export `ANDROID_SERIAL`, which every
-  `adb` call honours without `-s`.
+- **The emulator is `~/repos/emulator-tools`' business, not this repo's.**
+  `emu up` creates and boots the AVD named after this checkout (`ai-app-2`),
+  refusing when the machine has no room for one; `emu list` says what is
+  attached and what it costs; `emu down` stops it. `run-android.sh` is that
+  plus a build and an install. Run that repo's `install.sh` once if `emu` is
+  missing.
+  The `adb` on `PATH` after sourcing `android-env.sh` is that repo's wrapper,
+  which fills in `-s` from the same rule — so a bare `adb shell` reaches this
+  checkout's emulator and refuses to reach another one's. That defaulting is
+  what makes the old advice unnecessary rather than wrong: with two attached
+  and no `-s`, a bare `adb shell pm list packages` comes back **empty**,
+  which reads as the app having been uninstalled rather than as the question
+  being ambiguous.
 
 ## Where things run (host vs this VM)
 
diff --git a/app/run-android.sh b/app/run-android.sh
index 0da7949..3b65dae 100755
--- a/app/run-android.sh
+++ b/app/run-android.sh
@@ -1,7 +1,13 @@
 #!/bin/sh
-# Builds and runs this app on an emulator, creating/booting the AVD first if
-# it isn't already up. Same flow as dev-updater's run-android.sh; see that
-# script for the reasoning behind the avd handling.
+# Builds this app and runs it on this checkout's emulator.
+#
+# The emulator half of this -- which AVD this checkout means, creating it,
+# booting it headless, and refusing to start one the machine has no room for
+# -- lives in ~/repos/emulator-tools and is shared with every other Android
+# checkout here. This script kept its own copy of that sequence until
+# 2026-08-30, as did dev-updater's and ai-app's, and three copies of "boot an
+# emulator" is three places for the memory check that was missing from all of
+# them.
 #
 # Environment setup (SDK location, PATH, ...) lives in ./android-env.sh,
 # which can also be sourced directly for one-off commands.
@@ -9,105 +15,34 @@ set -eu
 
 APP_ID="com.example.aiapp"
 
-DEVICE_PROFILE="${DEVICE_PROFILE:-pixel_10}"
-SYSTEM_IMAGE="${SYSTEM_IMAGE:-system-images;android-36;google_apis;x86_64}"
-
 SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
 cd "$SCRIPT_DIR"
 
-# One AVD per checkout, named after it -- so two clones of this repo, or a
-# clone and a worktree, each get their own rather than fighting over one.
-# This used to default to a machine-wide "tdep", which made the emulator the
-# one thing here that could not be worked on in parallel: taking it meant
-# asking whoever had it, waiting, and handing it back, and installing onto a
-# running one steals the foreground from whatever they were looking at.
-# Derived rather than written down, so neither clone names the other's.
-# Override with AVD_NAME=... to share one deliberately.
-AVD_NAME="${AVD_NAME:-$(basename "$(dirname "$SCRIPT_DIR")")}"
-
 # shellcheck source=./android-env.sh
 . ./android-env.sh
 
-# Prints the adb serial of a running instance of AVD "$1", or nothing.
-avd_serial() {
-    for s in $(adb devices | awk '$2 == "device" {print $1}'); do
-        if [ "$(adb -s "$s" emu avd name 2>/dev/null | head -n1 | tr -d '\r')" = "$1" ]; then
-            echo "$s"
-            return 0
-        fi
-    done
-}
-
-echo "==> Ensuring emulator system image is installed"
-android sdk install emulator "$SYSTEM_IMAGE" || echo "    (non-fatal: see above)"
-
-if [ ! -f "$ANDROID_AVD_HOME/$AVD_NAME.ini" ]; then
-    echo "==> Creating AVD '$AVD_NAME' ($DEVICE_PROFILE, $SYSTEM_IMAGE)"
-    echo no | avdmanager create avd \
-        -n "$AVD_NAME" \
-        -k "$SYSTEM_IMAGE" \
-        --device "$DEVICE_PROFILE" \
-        --sdcard 512M
-else
-    echo "==> Reusing existing AVD '$AVD_NAME'"
+if ! command -v emu >/dev/null 2>&1; then
+    echo "run-android.sh: no 'emu' command." >&2
+    echo "  It comes from ~/repos/emulator-tools; run that repo's ./install.sh." >&2
+    exit 127
 fi
 
-# Host keyboard into the emulator -- this app has text fields.
-CONFIG_INI="$ANDROID_AVD_HOME/$AVD_NAME.avd/config.ini"
-if [ -f "$CONFIG_INI" ]; then
-    grep -v '^hw\.keyboard=' "$CONFIG_INI" >"$CONFIG_INI.tmp"
-    echo "hw.keyboard=yes" >>"$CONFIG_INI.tmp"
-    mv "$CONFIG_INI.tmp" "$CONFIG_INI"
-fi
-
-SERIAL=$(avd_serial "$AVD_NAME")
-if [ -n "$SERIAL" ]; then
-    echo "==> Emulator '$AVD_NAME' already running ($SERIAL)"
-else
-    # Clean up a stray/crashed process for this AVD, if any. The bracketed
-    # first character keeps the pattern from matching the shell running
-    # this script -- unbracketed, this kills that shell mid-run.
-    pkill -f "[e]mulator.*-avd $AVD_NAME" >/dev/null 2>&1 || true
-
-    EMU_LOG="/tmp/$AVD_NAME-emulator.log"
-    : >"$EMU_LOG"
-    if [ -n "${DISPLAY:-}" ] || [ -n "${WAYLAND_DISPLAY:-}" ]; then
-        echo "==> Starting emulator '$AVD_NAME' with GPU acceleration (-gpu host)"
-        emulator -avd "$AVD_NAME" -gpu host -no-audio >"$EMU_LOG" 2>&1 &
-    else
-        echo "==> No display -- starting emulator '$AVD_NAME' headless (-gpu swiftshader_indirect)"
-        emulator -avd "$AVD_NAME" -gpu swiftshader_indirect -no-audio -no-window \
-            >"$EMU_LOG" 2>&1 &
-    fi
-    EMU_PID=$!
-
-    i=0
-    booted=""
-    while [ "$i" -lt 150 ]; do
-        if ! kill -0 "$EMU_PID" 2>/dev/null; then
-            echo "Emulator process exited unexpectedly. Log output:" >&2
-            cat "$EMU_LOG" >&2
-            exit 1
-        fi
-        SERIAL=$(avd_serial "$AVD_NAME")
-        if [ -n "$SERIAL" ]; then
-            booted=$(adb -s "$SERIAL" shell getprop sys.boot_completed 2>/dev/null | tr -d '\r')
-            [ "$booted" = "1" ] && break
-        fi
-        i=$((i + 1))
-        sleep 2
-    done
-    if [ "$booted" != "1" ]; then
-        echo "Emulator did not finish booting in time. Log output:" >&2
-        cat "$EMU_LOG" >&2
-        exit 1
-    fi
-fi
+# Prints the serial, having created and booted the AVD if it had to. Named
+# after the checkout, so this cannot land on another session's emulator --
+# and refuses rather than starting one when the machine is short of memory,
+# because what an OOM kills is somebody else's work rather than the emulator
+# that asked for the memory.
+echo "==> Emulator"
+SERIAL=$(emu up)
+export ANDROID_SERIAL="$SERIAL"
 
 echo "==> Building debug APK"
 ./gradlew :androidApp:assembleDebug
 
 APK="androidApp/build/outputs/apk/debug/androidApp-debug.apk"
 echo "==> Installing and launching $APK"
-adb -s "$SERIAL" install -r "$APK"
-adb -s "$SERIAL" shell am start -n "$APP_ID/.MainActivity"
+# ANDROID_SERIAL above is what aims these; the adb wrapper would work it out
+# from the checkout anyway, but a script that says which device it means does
+# not depend on being run from the right directory.
+adb install -r "$APK"
+adb shell am start -n "$APP_ID/.MainActivity"