diff --git a/.woodpecker/agent-smoke.sh b/.woodpecker/agent-smoke.sh
index 6fe8f49..14a4607 100644
--- a/.woodpecker/agent-smoke.sh
+++ b/.woodpecker/agent-smoke.sh
@@ -21,10 +21,11 @@ FAILED=0
 # Uses awk instead of grep -Eo for busybox/Alpine compatibility (#296).
 get_fns() {
   local f="$1"
-  # BRE mode (no -E): () is literal in BRE, avoiding BusyBox ERE bugs
-  # where \(\) is misinterpreted. BRE one-or-more via [X][X]* instead of +.
-  grep '^[[:space:]]*[a-zA-Z_][a-zA-Z0-9_][a-zA-Z0-9_]*[[:space:]]*()' "$f" 2>/dev/null \
-    | sed 's/^[[:space:]]*//; s/[[:space:]]*().*$//' \
+  # BRE mode (no -E).  Use [(][)] for literal parens — unambiguous across
+  # GNU grep and BusyBox grep (some BusyBox builds treat bare () as grouping
+  # even in BRE).  BRE one-or-more via [X][X]* instead of +.
+  grep '^[[:space:]]*[a-zA-Z_][a-zA-Z0-9_][a-zA-Z0-9_]*[[:space:]]*[(][)]' "$f" 2>/dev/null \
+    | sed 's/^[[:space:]]*//; s/[[:space:]]*[(][)].*$//' \
     | sort -u || true
 }