Merge pull request #191 from CJackHwang/codex/fix-issue-in-pull-request-190

fix: prioritize quoted functionCall keys in tool sieve

internal/adapter/openai/tool_sieve_functioncall.go

@@ -5,18 +5,15 @@ import "strings"
 func findQuotedFunctionCallKeyStart(s string) int {
 	lower := strings.ToLower(s)
 	quotedIdx := findFunctionCallKeyStart(lower, `"functioncall"`)
-	baretIdx := findFunctionCallKeyStart(lower, "functioncall")
+	bareIdx := findFunctionCallKeyStart(lower, "functioncall")
 
-	switch {
-	case quotedIdx < 0:
-		return baretIdx
-	case baretIdx < 0:
+	// Prefer the quoted JSON key whenever we have a structural match.
+	// Bare-key detection is only for loose payloads where the quoted form
+	// is absent.
+	if quotedIdx >= 0 {
 		return quotedIdx
-	case quotedIdx < baretIdx:
-		return quotedIdx
-	default:
-		return baretIdx
 	}
+	return bareIdx
 }
 
 func findFunctionCallKeyStart(lower, key string) int {
@@ -26,6 +23,10 @@ func findFunctionCallKeyStart(lower, key string) int {
 			return -1
 		}
 		idx := from + rel
+		if isInsideJSONString(lower, idx) {
+			from = idx + 1
+			continue
+		}
 		if !hasJSONObjectContextPrefix(lower[:idx]) {
 			from = idx + 1
 			continue
@@ -39,6 +40,14 @@ func findFunctionCallKeyStart(lower, key string) int {
 			j++
 		}
 		if j < len(lower) && lower[j] == ':' {
+			k := j + 1
+			for k < len(lower) && (lower[k] == ' ' || lower[k] == '\t' || lower[k] == '\r' || lower[k] == '\n') {
+				k++
+			}
+			if k < len(lower) && lower[k] != '{' {
+				from = idx + 1
+				continue
+			}
 			return idx
 		}
 		from = idx + 1
@@ -46,6 +55,26 @@ func findFunctionCallKeyStart(lower, key string) int {
 	return -1
 }
 
+func isInsideJSONString(s string, idx int) bool {
+	inString := false
+	escaped := false
+	for i := 0; i < idx; i++ {
+		c := s[i]
+		if escaped {
+			escaped = false
+			continue
+		}
+		if c == '\\' && inString {
+			escaped = true
+			continue
+		}
+		if c == '"' {
+			inString = !inString
+		}
+	}
+	return inString
+}
+
 func hasJSONObjectContextPrefix(prefix string) bool {
 	return strings.LastIndex(prefix, "{") >= 0
 }

internal/adapter/openai/tool_sieve_functioncall_test.go

@@ -0,0 +1,23 @@
+package openai
+
+import "testing"
+
+func TestFindQuotedFunctionCallKeyStart_PrefersEarlierBareKey(t *testing.T) {
+	input := `{functionCall:{"name":"a","arguments":"{}"},"message":"literal text: \"functionCall\": not a key"}`
+
+	got := findQuotedFunctionCallKeyStart(input)
+	want := 1
+	if got != want {
+		t.Fatalf("findQuotedFunctionCallKeyStart() = %d, want %d", got, want)
+	}
+}
+
+func TestFindQuotedFunctionCallKeyStart_PrefersEarlierQuotedKey(t *testing.T) {
+	input := `{"functionCall":{"name":"a","arguments":"{}"},"note":"functionCall appears in prose"}`
+
+	got := findQuotedFunctionCallKeyStart(input)
+	want := 1
+	if got != want {
+		t.Fatalf("findQuotedFunctionCallKeyStart() = %d, want %d", got, want)
+	}
+}

internal/adapter/openai/tool_sieve_xml_test.go

@@ -143,6 +143,14 @@ func TestFindToolSegmentStartDetectsLooseFunctionCallKey(t *testing.T) {
 	}
 }
 
+func TestFindToolSegmentStartPrefersQuotedFunctionCallOverEarlierBareProse(t *testing.T) {
+	input := `prefix {note} functionCall: docs hint {"functionCall":{"name":"search_web","args":{"query":"x"}}}`
+	want := strings.Index(input, `{"functionCall"`)
+	if got := findToolSegmentStart(input); got != want {
+		t.Fatalf("expected quoted functionCall JSON start %d, got %d", want, got)
+	}
+}
+
 func TestFindToolSegmentStartIgnoresLooseFunctionCallProse(t *testing.T) {
 	input := "Please explain why functionCall: is used in documentation examples."
 	if got := findToolSegmentStart(input); got != -1 {