diff --git a/tools/ci/ps-drive-ref-check.sh b/tools/ci/ps-drive-ref-check.sh
index 9cf22dc40..57e16d276 100755
--- a/tools/ci/ps-drive-ref-check.sh
+++ b/tools/ci/ps-drive-ref-check.sh
@@ -27,7 +27,10 @@ for f in sorted(set(files)):
         if line.lstrip().startswith('#'): continue
         if sig.search(line):
             print(f'ps-params: {f}:{n}: a parameter named $args is shadowed by the automatic $args; rename it'); fail = 1
-        for seg in re.findall(r'"(?:[^"\\]|\\.|`")*"', line):
+        # a backtick escape (`" or any `x) is consumed FIRST: before 7 October 2026 the plain-character branch ate the backtick
+        # and the escaped quote ended the string, so `$first:` after a `" in pc1-arc-trace.ps1 sat outside every string
+        # and the job failed to parse on PC 1 (run-ia-arc-trace-20261007, 0 s)
+        for seg in re.findall(r'"(?:`.|[^"`\\]|\\.)*"', line):
             for m in pat.finditer(seg):
                 if m.group(1) in ok_names: continue
                 print(f'ps-drive-ref: {f}:{n}: `${m.group(1)}:` inside a double-quoted string parses as a drive-qualified variable in PowerShell 5.1; write `${{{m.group(1)}}}:`')
diff --git a/tools/intel-arc/pc1-arc-trace.ps1 b/tools/intel-arc/pc1-arc-trace.ps1
index 028d506ed..aca26831c 100644
--- a/tools/intel-arc/pc1-arc-trace.ps1
+++ b/tools/intel-arc/pc1-arc-trace.ps1
@@ -59,7 +59,7 @@ foreach ($mode in @('auto', 'local')) {
     else { "RESULT VERDICT $mode prefix equal over $n lines but the counts differ"; $verdicts[$mode] = 'count differs' }
     continue
   }
-  "RESULT VERDICT $mode first divergence at snapshot $first: gpu `"$($gpuLines[$first])`" cpu `"$($cpuLines[$first])`""
+  "RESULT VERDICT $mode first divergence at snapshot ${first}: gpu `"$($gpuLines[$first])`" cpu `"$($cpuLines[$first])`""
   $lo = [math]::Max(0, $first - 6); $hi = [math]::Min($n - 1, $first + 6)
   for ($k = $lo; $k -le $hi; $k++) { "RESULT ctx $mode $k $(if ($gpuLines[$k] -eq $cpuLines[$k]) { 'same' } else { 'DIFF' }) gpu=$($gpuLines[$k] -replace '^TRACE \d+ ', '') cpu=$($cpuLines[$k] -replace '^TRACE \d+ ', '')" }
   # which registers differ at the first divergence, and how many of the later snapshots agree again (a one-off vs a cascade)