fix(tests): make required-stack.bats portable across nodes with different app rosters

Found live during the .5 multinode-pass run: this suite was hardcoded to
.116's exact app bundle (including the mempool stack), so any node missing
an app hard-failed instead of skipping — and a missing local fail() helper
(present in 3 sibling bats files, absent here) masked the real error as
"command not found" (exit 127). Add the same skip-if-absent idiom already
used in mempool.bats per-app, and define fail() locally like the others.
Verified: skips cleanly on .116 (no bitcoin-knots here), still exercises
real checks for apps that are installed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/lifecycle/bats/required-stack.bats

@@ -1,7 +1,14 @@
 #!/usr/bin/env bats
 # tests/lifecycle/bats/required-stack.bats
 #
-# Read-only release-gate checks for the required Bitcoin stack on .116.
+# Read-only release-gate checks for the Bitcoin/electrum/lnd/mempool stack.
+# Originally written against .116's fixed app roster; the "present"/"running"
+# checks below now only require containers actually installed on THIS node
+# (podman_all_names — present in `podman ps -a` even if stopped), so a node
+# with a different app subset (e.g. no mempool stack) doesn't hard-fail on
+# apps it was never meant to have. Per-app checks further down (mempool,
+# filebrowser, ...) skip individually if that app isn't installed, matching
+# the mempool_skip_if_absent idiom in mempool.bats.
 #
 # This suite is intentionally non-destructive and does not use RPC auth;
 # it can run anytime as a health gate during long sync/reindex windows.
@@ -19,15 +26,38 @@ required_containers=(
   "archy-electrs-ui"
 )
 
+fail() { echo "$@" >&2; return 1; }
+
 podman_names() {
   podman ps --format '{{.Names}}'
 }
 
+podman_all_names() {
+  podman ps -a --format '{{.Names}}'
+}
+
 container_running() {
   local name="$1"
   podman inspect --format '{{.State.Running}}' "$name" 2>/dev/null
 }
 
+container_installed() {
+  local name="$1"
+  podman_all_names | grep -Fx "$name" >/dev/null
+}
+
+skip_if_not_installed() {
+  container_installed "$1" || skip "$1 not installed on this node"
+}
+
+# The subset of required_containers actually installed on this node.
+installed_required_containers() {
+  local c
+  for c in "${required_containers[@]}"; do
+    container_installed "$c" && echo "$c"
+  done
+}
+
 bitcoin_rpc() {
   curl -fsS --max-time 60 \
     --user "archipelago:$(cat /var/lib/archipelago/secrets/bitcoin-rpc-password)" \
@@ -42,13 +72,16 @@ bitcoin_json() {
 
 @test "required containers are present" {
   # Under sustained 5× churn an app may still be mid-restart when this runs;
-  # wait for the whole required set rather than single-shot.
+  # wait for the whole required set rather than single-shot. Only checks
+  # containers actually installed on this node (see installed_required_containers).
+  local targets; targets="$(installed_required_containers)"
+  [[ -n "$targets" ]] || skip "none of required_containers installed on this node"
   local deadline=$(( $(date +%s) + 180 )) names missing
   while (( $(date +%s) < deadline )); do
     names="$(podman_names)"; missing=""
-    for c in "${required_containers[@]}"; do
+    while IFS= read -r c; do
       echo "$names" | grep -Fx "$c" >/dev/null || missing="$missing $c"
-    done
+    done <<< "$targets"
     [[ -z "$missing" ]] && return 0
     sleep 3
   done
@@ -56,12 +89,14 @@ bitcoin_json() {
 }
 
 @test "required containers are running" {
+  local targets; targets="$(installed_required_containers)"
+  [[ -n "$targets" ]] || skip "none of required_containers installed on this node"
   local deadline=$(( $(date +%s) + 180 )) notrunning
   while (( $(date +%s) < deadline )); do
     notrunning=""
-    for c in "${required_containers[@]}"; do
+    while IFS= read -r c; do
       [[ "$(container_running "$c" 2>/dev/null)" == "true" ]] || notrunning="$notrunning $c"
-    done
+    done <<< "$targets"
     [[ -z "$notrunning" ]] && return 0
     sleep 3
   done
@@ -69,12 +104,14 @@ bitcoin_json() {
 }
 
 @test "bitcoin-knots RPC responds" {
+  skip_if_not_installed bitcoin-knots
   run bitcoin_rpc
   [ "$status" -eq 0 ]
   echo "$output" | python3 -c 'import json,sys; r=json.load(sys.stdin)["result"]; assert r["chain"] == "main" and r["blocks"] >= 0'
 }
 
 @test "bitcoin backend is synced archival for electrumx/lnd gate" {
+  skip_if_not_installed bitcoin-knots
   run bitcoin_rpc
   [ "$status" -eq 0 ]
 
@@ -95,6 +132,7 @@ bitcoin_json() {
 }
 
 @test "electrumx TCP port accepts connections" {
+  skip_if_not_installed electrumx
   run python3 - <<'PY'
 import socket
 s = socket.create_connection(("127.0.0.1", 50001), 3)
@@ -105,6 +143,7 @@ PY
 }
 
 @test "lnd CLI getinfo succeeds" {
+  skip_if_not_installed lnd
   # lnd RPC readiness lags the container "running" state (wallet auto-unlock on
   # start), so retry until ready rather than single-shot. See lnd.bats note.
   run sh -lc 'for i in $(seq 1 30); do
@@ -115,6 +154,7 @@ PY
 }
 
 @test "lnd REST port accepts connections" {
+  skip_if_not_installed lnd
   run python3 - <<'PY'
 import socket
 s = socket.create_connection(("127.0.0.1", 18080), 3)
@@ -125,17 +165,20 @@ PY
 }
 
 @test "mempool api endpoint responds" {
+  skip_if_not_installed mempool-api
   # mempool-api reconnects to electrumx after a stack restart — retry ~180s.
   run sh -lc 'for i in $(seq 1 60); do curl -fsS -m 5 -o /dev/null "http://127.0.0.1:8999/api/v1/backend-info" && exit 0; sleep 3; done; exit 1'
   [ "$status" -eq 0 ]
 }
 
 @test "mempool frontend responds" {
+  skip_if_not_installed mempool
   run sh -lc 'for i in $(seq 1 60); do curl -fsS -m 5 -o /dev/null "http://127.0.0.1:4080/" && exit 0; sleep 3; done; exit 1'
   [ "$status" -eq 0 ]
 }
 
 @test "bitcoin ui responds" {
+  skip_if_not_installed archy-bitcoin-ui
   # The companion (archy-bitcoin-ui) may have just been recreated by an earlier
   # companion-survives test; its nginx takes a moment to serve. Retry ~120s
   # rather than single-shot.
@@ -144,11 +187,13 @@ PY
 }
 
 @test "lnd ui responds" {
+  skip_if_not_installed archy-lnd-ui
   run curl -fsS "http://127.0.0.1:18083/"
   [ "$status" -eq 0 ]
 }
 
 @test "filebrowser responds" {
+  skip_if_not_installed filebrowser
   run curl -fsS "http://127.0.0.1:8083/"
   [ "$status" -eq 0 ]
 }