#30 Tier 1.5: Headless Server Mode

Context

After disabling 51+ user-facing packages with boot-debloat (Hack #26) and the extended pass (Hack #27), dumpsys meminfo still showed four heavyweight system services consuming 187 MB combined. These services exist to provide the phone's interactive UI layer: the status bar, notification shade, lock screen, phone dialer, media scanner, and certificate management. On a headless server that will never display a UI or make phone calls, all of this is dead weight.

The Moto E2 is running as a dedicated PocketClaw gateway. Nobody touches the screen. There is no SIM card. The only interfaces are SSH and HTTP. The question was: can Android function as a WiFi-connected headless server without these core system services?

The answer is yes — with caveats.

Implementation

These disables require Dirty COW root (Hack #34) because they target core Android system packages that adb shell pm disable-user refuses to touch.

# Run from ADB shell after Dirty COW root
# (inside boot-debloat.sh or manually)

# SystemUI — status bar, notification shade, lock screen, recent apps
# 70 MB RSS. Largest single system service.
pm disable com.android.systemui

# Phone / Dialer — telephony stack
# 42 MB RSS. No SIM card, no calls needed.
pm disable com.android.phone

# Media Provider — media scanner, thumbnail generation
# 40 MB RSS. No photos, no music, no videos on this device.
pm disable com.android.providers.media

# Keychain — certificate management for apps
# 35 MB RSS. Gateway uses Node.js TLS with ca-certificates, not Android keychain.
pm disable com.android.keychain

Add to the automated boot-debloat script so they're disabled after every reboot:

# Append to /data/local/tmp/boot-debloat.sh (or stop-daemons.sh)
# These run after Dirty COW grants root

HEADLESS_PACKAGES="
com.android.systemui
com.android.phone
com.android.providers.media
com.android.keychain
"

for pkg in $HEADLESS_PACKAGES; do
  pm disable "$pkg" 2>/dev/null && echo "Disabled: $pkg"
done

Verification

# Verify all four are disabled:
adb shell pm list packages -d | grep -E "systemui|phone|providers.media|keychain"
# Expected:
# package:com.android.systemui
# package:com.android.phone
# package:com.android.keychain
# package:com.android.providers.media

# Check RAM usage before and after:
adb shell dumpsys meminfo | head -20
# Look for "Total RAM" and "Used RAM" lines

# Verify WiFi still works:
adb shell ping -c 3 8.8.8.8
# Expected: 3 packets transmitted, 3 received

# Verify gateway is accessible:
curl -s http://localhost:9000/api/status
# Expected: JSON response (via adb forward tcp:9000 tcp:9000)

# Check SystemUI respawn state:
adb shell ps | grep systemui
# Expected: either absent or running with ~5 MB RSS (degraded mode)

Gotchas

• SystemUI does NOT stay dead. Android's system_server detects the crash and restarts SystemUI in a degraded fallback mode. The respawned SystemUI uses only ~5 MB RSS instead of the original 70 MB, so the net savings is ~65 MB rather than 70 MB. Trying to kill or disable it repeatedly in a loop is counterproductive — let it respawn in degraded mode
• Disabling com.android.phone removes ALL telephony: no calls, no SMS, no mobile data. This is fine for a WiFi-only server but means you cannot use the phone as an actual phone until you re-enable it
• The Media Provider disable breaks the system gallery, camera, and any app that queries content://media/. Since PocketClaw never uses the media content provider, this is harmless
• Disabling Keychain means Android apps that use the system certificate store for client certificates will fail. Node.js manages its own TLS through OpenSSL and the ca-certificates bundle, so the gateway is unaffected
• If you need to temporarily use the phone's UI (e.g., to change WiFi settings manually), re-enable SystemUI first: pm enable com.android.systemui. The full UI returns within seconds
• These disables persist across reboots via package-restrictions.xml in /data/system/users/0/. The Dirty COW root is only needed for the initial disable, not to maintain the state

Result