add logic to identify a wrong connect usage.

android/termux-setup/50_mod_adb.sh

@@ -4,6 +4,92 @@
 # -------------------------
 # ADB wireless pair/connect wizard
 # -------------------------
+
+# Local stamp so we can detect "connect-only" misuse after reinstall/clear-data.
+ADB_PAIRED_STAMP="${ADB_STATE_DIR}/stamp.adb_paired"
+
+adb_hostkey_fingerprint() {
+  # Returns a stable fingerprint for THIS Termux install's adb host key.
+  local pub="${HOME}/.android/adbkey.pub"
+  [[ -r "$pub" ]] || return 1
+  if have sha256sum; then
+    sha256sum "$pub" | awk '{print $1}'
+  elif have shasum; then
+    shasum -a 256 "$pub" | awk '{print $1}'
+  elif have openssl; then
+    openssl dgst -sha256 "$pub" 2>/dev/null | awk '{print $2}'
+  elif have md5sum; then
+    md5sum "$pub" | awk '{print $1}'
+  else
+    return 1
+  fi
+}
+
+adb_stamp_write() {
+  # args: mode serial
+  local mode="$1" serial="$2" fp=""
+  fp="$(adb_hostkey_fingerprint 2>/dev/null || true)"
+  {
+    echo "ts=$(date -Is 2>/dev/null || date || true)"
+    echo "mode=${mode}"
+    echo "host=${HOST}"
+    echo "serial=${serial}"
+    echo "connect_port=${CONNECT_PORT:-}"
+    echo "hostkey_fp=${fp}"
+  } >"$ADB_PAIRED_STAMP" 2>/dev/null || true
+  chmod 600 "$ADB_PAIRED_STAMP" 2>/dev/null || true
+}
+
+adb_stamp_read_fp() {
+  [[ -r "$ADB_PAIRED_STAMP" ]] || return 1
+  sed -n 's/^hostkey_fp=//p' "$ADB_PAIRED_STAMP" 2>/dev/null | head -n 1
+}
+
+adb_warn_connect_only_if_suspicious() {
+  # Called only in connect-only flows.
+  local cur_fp old_fp
+  cur_fp="$(adb_hostkey_fingerprint 2>/dev/null || true)"
+  old_fp="$(adb_stamp_read_fp 2>/dev/null || true)"
+
+  if [[ ! -f "$ADB_PAIRED_STAMP" ]]; then
+    warn "connect-only assumes THIS Termux install has been paired before."
+    warn "No local pairing stamp found ($ADB_PAIRED_STAMP)."
+    warn "If you reinstalled Termux / cleared data / changed user, you must re-pair (run: --adb-only)."
+    [[ -n "$cur_fp" ]] && warn "Current ADB hostkey fingerprint: ${cur_fp:0:12}..."
+    return 0
+  fi
+
+  if [[ -n "$old_fp" && -n "$cur_fp" && "$old_fp" != "$cur_fp" ]]; then
+    warn_red "ADB host key changed since last pairing stamp."
+    warn "Old fingerprint: ${old_fp:0:12}...  Current: ${cur_fp:0:12}..."
+    warn "Android Wireless debugging -> Paired devices: remove the old entry, then run: --adb-only"
+  fi
+}
+
+adb_connect_verify() {
+  # args: serial (HOST:PORT)
+  local serial="$1" out rc start now state
+  set +e
+  out="$(adb connect "$serial" 2>&1)"
+  rc=$?
+  set -e
+
+  # Always verify via `adb devices` (adb may exit 0 even on failure).
+  start="$(date +%s)"
+  while true; do
+    state="$(adb_device_state "$serial" || true)"
+    [[ "$state" == "device" ]] && { printf '%s\n' "$out"; return 0; }
+    now="$(date +%s)"
+    (( now - start >= 5 )) && break
+    sleep 1
+  done
+
+  warn_red "adb connect did not result in a usable device entry for: $serial (state='${state:-none}')."
+  warn "adb connect output: ${out:-<none>}"
+  warn "If you recently reinstalled Termux/cleared data, the phone may show an OLD paired device. Remove it and re-pair."
+  return 1
+}
+
 cleanup_offline_loopback() {
   local keep_serial="$1"  # e.g. 127.0.0.1:41313
   local serial state rest
@@ -28,6 +114,7 @@ adb_pair_connect() {
   adb start-server >/dev/null 2>&1 || true
 
   if [[ "$ONLY_CONNECT" == "1" ]]; then
+    adb_warn_connect_only_if_suspicious
     if [[ -n "$CONNECT_PORT" ]]; then
       CONNECT_PORT="${CONNECT_PORT//[[:space:]]/}"
       [[ "$CONNECT_PORT" =~ ^[0-9]{5}$ ]] || die "Invalid CONNECT PORT (must be 5 digits): '$CONNECT_PORT'"
@@ -39,7 +126,7 @@ adb_pair_connect() {
     local serial="${HOST}:${CONNECT_PORT}"
     adb disconnect "$serial" >/dev/null 2>&1 || true
     echo "[*] adb connect $serial"
-    adb connect "$serial" >/dev/null || die "adb connect failed to $serial. Verify Wireless debugging is enabled and CONNECT PORT is correct."
+    adb_connect_verify "$serial" >/dev/null || die "adb connect failed to $serial. Verify Wireless debugging is enabled, and pairing exists for THIS Termux install."
 
     if [[ "$CLEANUP_OFFLINE" == "1" ]]; then
       cleanup_offline_loopback "$serial"
@@ -50,6 +137,7 @@ adb_pair_connect() {
 
     echo "[*] ADB check (shell):"
     adb -s "$serial" shell sh -lc 'echo "it worked: adb shell is working"; id' || true
+    adb_stamp_write "connect-only" "$serial"
 
     cleanup_notif
     ok "ADB connected (connect-only): $serial"
@@ -79,7 +167,7 @@ adb_pair_connect() {
   printf '%s\n' "$code" | adb pair "${HOST}:${pair_port}" || die "adb pair failed. Verify PAIR PORT and PAIR CODE (and that the pairing dialog is showing)."
 
   echo "[*] adb connect $serial"
-  adb connect "$serial" >/dev/null || die "adb connect failed after pairing. Re-check CONNECT PORT and Wireless debugging."
+  adb_connect_verify "$serial" >/dev/null || die "adb connect failed after pairing. Re-check CONNECT PORT and Wireless debugging."
 
   if [[ "$CLEANUP_OFFLINE" == "1" ]]; then
     cleanup_offline_loopback "$serial"
@@ -90,6 +178,7 @@ adb_pair_connect() {
 
   echo "[*] ADB check (shell):"
   adb -s "$serial" shell sh -lc 'echo "it worked: adb shell is working"; getprop ro.product.model; getprop ro.build.version.release' || true
+  adb_stamp_write "paired" "$serial"
 
   cleanup_notif
   ok "ADB connected: $serial"