Report an unreadable node log in the interop harness as not established

count_log_pattern prints unreadable:<container> and fails when a node's
logs cannot be read, but only two of its callers checked that. The rest
compared the text as a number: the first-rekey check reported "no FMP
rekey cutover observed", the second-cycle wait aborted the run on an
unbound variable before the log analysis, and the log analysis read the
rekey totals as zero. Each now checks the status and reports the count
as not established.

testing/interop/interop-test.sh

@@ -574,14 +574,19 @@ count_node_pattern() {
     docker logs "${CONTAINER[$node]}" 2>&1 | grep -cE "$pattern" || true
 }
 
+# Wait until the count of a pattern across all node logs reaches
+# min_count. Returns 0 when it does, 1 on timeout, and 2 at once when a
+# node's logs cannot be read, since no count is established then; the
+# caller reports that when it takes its own count.
 wait_for_log_pattern_count() {
     local pattern="$1" min_count="$2" timeout="$3"
-    local start=$SECONDS
+    local start=$SECONDS count
-    while (( SECONDS - start < timeout )); do
+    while :; do
-        [ "$(count_log_pattern "$pattern")" -ge "$min_count" ] && return 0
+        count="$(count_log_pattern "$pattern")" || return 2
+        [ "$count" -ge "$min_count" ] && return 0
+        (( SECONDS - start < timeout )) || return 1
         sleep "$LOG_POLL_INTERVAL"
     done
-    [ "$(count_log_pattern "$pattern")" -ge "$min_count" ]
 }
 
 # One node's bloom-union mesh-size estimate, or "null" when the daemon
@@ -866,8 +871,11 @@ PASSED=0; FAILED=0
 wait_for_log_pattern_count \
     "Rekey cutover complete \(initiator\), K-bit flipped" 1 \
     "$FIRST_REKEY_TIMEOUT" || true
-fmp_cutovers="$(count_log_pattern 'Rekey cutover complete \(initiator\), K-bit flipped')"
+if ! fmp_cutovers="$(count_log_pattern 'Rekey cutover complete \(initiator\), K-bit flipped')"; then
-if [ "$fmp_cutovers" -ge 1 ]; then
+    echo "  FAIL  FMP rekey cutovers: node logs unreadable ($fmp_cutovers), not established"
+    FAILED=$((FAILED + 1))
+    INTEROP_FAILURES+=("[log] FMP rekey cutovers: node logs unreadable ($fmp_cutovers)")
+elif [ "$fmp_cutovers" -ge 1 ]; then
     echo "  PASS  FMP rekey initiator cutovers: $fmp_cutovers"
     PASSED=$((PASSED + 1))
 else
@@ -897,10 +905,17 @@ echo "Phase 4: Second rekey cycle (waiting up to ${SECOND_REKEY_WAIT}s for the n
 # the same pre/post cutover-count delta convention as the control window
 # (Phase 1b), instead of a blind sleep. Bounded by SECOND_REKEY_WAIT so a
 # stalled rekey falls through to the strict Phase 5/6 assertions.
-fmp_cutovers_before="$(count_log_pattern 'Rekey cutover complete \(initiator\), K-bit flipped')"
+# An unreadable baseline gives nothing to wait beyond, so do not wait.
-wait_for_log_pattern_count \
+# Phase 4 keeps no PASSED/FAILED of its own; the INTEROP_FAILURES entry
-    "Rekey cutover complete \(initiator\), K-bit flipped" \
+# is what turns the run red.
-    "$((fmp_cutovers_before + 1))" "$SECOND_REKEY_WAIT" || true
+if fmp_cutovers_before="$(count_log_pattern 'Rekey cutover complete \(initiator\), K-bit flipped')"; then
+    wait_for_log_pattern_count \
+        "Rekey cutover complete \(initiator\), K-bit flipped" \
+        "$((fmp_cutovers_before + 1))" "$SECOND_REKEY_WAIT" || true
+else
+    echo "  FAIL  second rekey cycle: node logs unreadable ($fmp_cutovers_before), baseline not established"
+    INTEROP_FAILURES+=("[log] second rekey cycle: node logs unreadable ($fmp_cutovers_before)")
+fi
 echo ""
 
 echo "Phase 5: Post-second-rekey connectivity (reconverge within ${POST_REKEY_TIMEOUT}s)"
@@ -1015,16 +1030,22 @@ done
 # Positive checks — the rekey machinery actually exercised both layers.
 echo ""
 echo "  -- Rekey machinery exercised --"
-fmp_total="$(count_log_pattern 'Rekey cutover complete \(initiator\), K-bit flipped')"
+# An unreadable log means the harness observed nothing, so it is a FAIL
-fsp_total="$(count_log_pattern 'FSP rekey cutover complete')"
+# on either layer; the FSP WARN below is for a readable zero only.
-if [ "$fmp_total" -ge 1 ]; then
+if ! fmp_total="$(count_log_pattern 'Rekey cutover complete \(initiator\), K-bit flipped')"; then
+    echo "    FAIL  FMP rekey cutovers: node logs unreadable ($fmp_total), not established"
+    FAILED=$((FAILED + 1))
+elif [ "$fmp_total" -ge 1 ]; then
     echo "    PASS  FMP rekey cutovers across mesh: $fmp_total"
     PASSED=$((PASSED + 1))
 else
     echo "    FAIL  FMP rekey cutovers: $fmp_total (expected >= 1)"
     FAILED=$((FAILED + 1))
 fi
-if [ "$fsp_total" -ge 1 ]; then
+if ! fsp_total="$(count_log_pattern 'FSP rekey cutover complete')"; then
+    echo "    FAIL  FSP rekey cutovers: node logs unreadable ($fsp_total), not established"
+    FAILED=$((FAILED + 1))
+elif [ "$fsp_total" -ge 1 ]; then
     echo "    PASS  FSP rekey cutovers across mesh: $fsp_total"
     PASSED=$((PASSED + 1))
 else