fix(openai): strip leaked tool result markers

internal/httpapi/openai/shared/leaked_output_sanitize.go

@@ -10,6 +10,9 @@ import (
 var emptyJSONFencePattern = regexp.MustCompile("(?is)```json\\s*```")
 var leakedToolCallArrayPattern = regexp.MustCompile(`(?is)\[\{\s*"function"\s*:\s*\{[\s\S]*?\}\s*,\s*"id"\s*:\s*"call[^"]*"\s*,\s*"type"\s*:\s*"function"\s*}\]`)
 var leakedToolResultBlobPattern = regexp.MustCompile(`(?is)<\s*\|\s*tool\s*\|\s*>\s*\{[\s\S]*?"tool_call_id"\s*:\s*"call[^"]*"\s*}`)
+var leakedToolResultOpenMarkerPattern = regexp.MustCompile(`(?is)<[\|\x{ff5c}]\s*tool\s*[\|\x{ff5c}]>`)
+var leakedToolResultCloseMarkerPattern = regexp.MustCompile(`(?is)<[\|\x{ff5c}]\s*end[_▁]of[_▁]tool[_▁]?results\s*[\|\x{ff5c}]>`)
+var leakedToolResultSectionPattern = regexp.MustCompile(`(?is)<[\|\x{ff5c}]\s*tool\s*[\|\x{ff5c}]>[\s\S]*?<[\|\x{ff5c}]\s*end[_▁]of[_▁]tool[_▁]?results\s*[\|\x{ff5c}]>`)
 
 var leakedThinkTagPattern = regexp.MustCompile(`(?is)</?\s*think\s*>`)
 
@@ -29,7 +32,8 @@ var leakedThoughtMarkerPattern = regexp.MustCompile(`(?i)<[\|\x{ff5c}]\s*(?:begi
 // halfwidth or legacy U+FF5C fullwidth delimiters:
 //   - ASCII underscore: <|end_of_sentence|>, <|end_of_toolresults|>, <|end_of_instructions|>
 //   - U+2581 variant:   <|end▁of▁sentence|>, <|end▁of▁toolresults|>, <|end▁of▁instructions|>
-var leakedMetaMarkerPattern = regexp.MustCompile(`(?i)<[\|\x{ff5c}]\s*(?:assistant|tool|end[_▁]of[_▁]sentence|end[_▁]of[_▁]thinking|end[_▁]of[_▁]thought|end[_▁]of[_▁]toolresults|end[_▁]of[_▁]instructions)\s*[\|\x{ff5c}]>`)
+//   - compound assistant markers: <|Assistant_END_OF_TOOL_CALLS|>
+var leakedMetaMarkerPattern = regexp.MustCompile(`(?i)<[\|\x{ff5c}]\s*(?:assistant(?:[_▁]end[_▁]of[_▁]tool[_▁]?calls)?|tool|end[_▁]of[_▁]sentence|end[_▁]of[_▁]thinking|end[_▁]of[_▁]thought|end[_▁]of[_▁]tool[_▁]?results|end[_▁]of[_▁]tool[_▁]?calls|end[_▁]of[_▁]instructions)\s*[\|\x{ff5c}]>`)
 
 // leakedAgentXMLBlockPatterns catch agent-style XML blocks that leak through
 // when the sieve fails to capture them. These are applied only to complete
@@ -52,6 +56,7 @@ func sanitizeLeakedOutput(text string) string {
 	}
 	out := emptyJSONFencePattern.ReplaceAllString(text, "")
 	out = leakedToolCallArrayPattern.ReplaceAllString(out, "")
+	out = leakedToolResultSectionPattern.ReplaceAllString(out, "")
 	out = leakedToolResultBlobPattern.ReplaceAllString(out, "")
 	out = stripDanglingThinkSuffix(out)
 	out = leakedThinkTagPattern.ReplaceAllString(out, "")
@@ -63,6 +68,40 @@ func sanitizeLeakedOutput(text string) string {
 	return out
 }
 
+func stripLeakedToolResultSectionsDelta(text string, inside *bool) string {
+	if text == "" || inside == nil {
+		return text
+	}
+	var b strings.Builder
+	pos := 0
+	for pos < len(text) {
+		if *inside {
+			loc := leakedToolResultCloseMarkerPattern.FindStringIndex(text[pos:])
+			if loc == nil {
+				return b.String()
+			}
+			*inside = false
+			pos += loc[1]
+			continue
+		}
+		loc := leakedToolResultOpenMarkerPattern.FindStringIndex(text[pos:])
+		if loc == nil {
+			b.WriteString(text[pos:])
+			break
+		}
+		start := pos + loc[0]
+		openEnd := pos + loc[1]
+		b.WriteString(text[pos:start])
+		closeLoc := leakedToolResultCloseMarkerPattern.FindStringIndex(text[openEnd:])
+		if closeLoc == nil {
+			*inside = true
+			break
+		}
+		pos = openEnd + closeLoc[1]
+	}
+	return b.String()
+}
+
 func stripLeakedToolCallWrapperBlocks(text string) string {
 	if text == "" {
 		return text

internal/httpapi/openai/shared/stream_accumulator.go

@@ -16,6 +16,9 @@ type StreamAccumulator struct {
 	ToolDetectionThinking strings.Builder
 	RawText               strings.Builder
 	Text                  strings.Builder
+
+	thinkingToolResultSectionOpen bool
+	textToolResultSectionOpen     bool
 }
 
 type StreamPartDelta struct {
@@ -69,7 +72,8 @@ func (a *StreamAccumulator) applyThinkingPart(text string) StreamPartDelta {
 	if !a.ThinkingEnabled || rawTrimmed == "" {
 		return delta
 	}
-	cleanedText := CleanVisibleOutput(rawTrimmed, a.StripReferenceMarkers)
+	visibleCandidate := stripLeakedToolResultSectionsDelta(rawTrimmed, &a.thinkingToolResultSectionOpen)
+	cleanedText := CleanVisibleOutput(visibleCandidate, a.StripReferenceMarkers)
 	if cleanedText == "" {
 		return delta
 	}
@@ -89,11 +93,15 @@ func (a *StreamAccumulator) applyTextPart(text string) StreamPartDelta {
 	}
 	a.RawText.WriteString(rawTrimmed)
 	delta := StreamPartDelta{Type: "text", RawText: rawTrimmed}
-	if a.SearchEnabled && sse.IsCitation(rawTrimmed) {
+	visibleCandidate := stripLeakedToolResultSectionsDelta(rawTrimmed, &a.textToolResultSectionOpen)
+	if visibleCandidate == "" {
+		return delta
+	}
+	if a.SearchEnabled && sse.IsCitation(visibleCandidate) {
 		delta.CitationOnly = true
 		return delta
 	}
-	cleanedText := CleanVisibleOutput(rawTrimmed, a.StripReferenceMarkers)
+	cleanedText := CleanVisibleOutput(visibleCandidate, a.StripReferenceMarkers)
 	trimmed := sse.TrimContinuationOverlapFromBuilder(&a.Text, cleanedText)
 	if trimmed == "" {
 		return delta

internal/httpapi/openai/shared/stream_accumulator_test.go

@@ -96,6 +96,87 @@ func TestStreamAccumulatorSuppressesCitationTextWhenSearchEnabled(t *testing.T)
 	}
 }
 
+func TestStreamAccumulatorStripsToolResultSectionAcrossTextChunks(t *testing.T) {
+	acc := StreamAccumulator{StripReferenceMarkers: true}
+	first := acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "text", Text: "visible:<|Tool|>"}},
+	})
+	second := acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "text", Text: `[{"content":"secret","tool_call_id":"call_123"}]`}},
+	})
+	third := acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "text", Text: "<|end_of_toolresults|> after"}},
+	})
+
+	if got := acc.RawText.String(); got != `visible:<|Tool|>[{"content":"secret","tool_call_id":"call_123"}]<|end_of_toolresults|> after` {
+		t.Fatalf("raw text = %q", got)
+	}
+	if got := acc.Text.String(); got != "visible: after" {
+		t.Fatalf("visible text = %q", got)
+	}
+	if !first.ContentSeen || !second.ContentSeen || !third.ContentSeen {
+		t.Fatalf("expected all chunks to mark upstream content")
+	}
+	if got := first.Parts[0].VisibleText; got != "visible:" {
+		t.Fatalf("first visible delta = %q", got)
+	}
+	if got := second.Parts[0].VisibleText; got != "" {
+		t.Fatalf("payload visible delta = %q", got)
+	}
+	if got := third.Parts[0].VisibleText; got != " after" {
+		t.Fatalf("closing visible delta = %q", got)
+	}
+}
+
+func TestStreamAccumulatorStripsFullwidthToolResultSectionAcrossTextChunks(t *testing.T) {
+	acc := StreamAccumulator{StripReferenceMarkers: true}
+	acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "text", Text: "x<｜Tool｜>"}},
+	})
+	acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "text", Text: `{"content":"secret"}`}},
+	})
+	acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "text", Text: "<｜end▁of▁toolresults｜>y"}},
+	})
+
+	if got := acc.Text.String(); got != "xy" {
+		t.Fatalf("visible text = %q", got)
+	}
+}
+
+func TestStreamAccumulatorStripsToolResultSectionAcrossThinkingChunks(t *testing.T) {
+	acc := StreamAccumulator{ThinkingEnabled: true, StripReferenceMarkers: true}
+	acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "thinking", Text: "thought <|Tool|>"}},
+	})
+	payload := acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "thinking", Text: `[{"content":"secret"}]`}},
+	})
+	acc.Apply(sse.LineResult{
+		Parsed: true,
+		Parts:  []sse.ContentPart{{Type: "thinking", Text: "<|end_of_toolresults|>resumes"}},
+	})
+
+	if got := acc.RawThinking.String(); got != `thought <|Tool|>[{"content":"secret"}]<|end_of_toolresults|>resumes` {
+		t.Fatalf("raw thinking = %q", got)
+	}
+	if got := acc.Thinking.String(); got != "thought resumes" {
+		t.Fatalf("visible thinking = %q", got)
+	}
+	if got := payload.Parts[0].VisibleText; got != "" {
+		t.Fatalf("payload visible delta = %q", got)
+	}
+}
+
 func TestStreamAccumulatorStripsInlineCitationAndReferenceMarkers(t *testing.T) {
 	acc := StreamAccumulator{SearchEnabled: true, StripReferenceMarkers: true}
 	result := acc.Apply(sse.LineResult{