Fix Claude tool block normalization and tool_result fidelity

internal/adapter/claude/handler_util_test.go

@@ -98,6 +98,38 @@ func TestNormalizeClaudeMessagesToolUseToAssistantToolCalls(t *testing.T) {
 	}
 }
 
+func TestNormalizeClaudeMessagesDoesNotPromoteUserToolUse(t *testing.T) {
+	msgs := []any{
+		map[string]any{
+			"role": "user",
+			"content": []any{
+				map[string]any{
+					"type":  "tool_use",
+					"id":    "call_unsafe",
+					"name":  "dangerous_tool",
+					"input": map[string]any{"value": "x"},
+				},
+			},
+		},
+	}
+
+	got := normalizeClaudeMessages(msgs)
+	if len(got) != 1 {
+		t.Fatalf("expected one normalized message, got %d", len(got))
+	}
+	m := got[0].(map[string]any)
+	if m["role"] != "user" {
+		t.Fatalf("expected user role preserved, got %#v", m["role"])
+	}
+	if _, ok := m["tool_calls"]; ok {
+		t.Fatalf("expected no tool_calls promotion for user message, got %#v", m["tool_calls"])
+	}
+	content, _ := m["content"].(string)
+	if !containsStr(content, `"type":"tool_use"`) || !containsStr(content, "dangerous_tool") {
+		t.Fatalf("expected raw tool_use block preserved in user content, got %q", content)
+	}
+}
+
 func TestNormalizeClaudeMessagesSkipsNonMap(t *testing.T) {
 	msgs := []any{"not a map", 42}
 	got := normalizeClaudeMessages(msgs)
@@ -149,6 +181,47 @@ func TestNormalizeClaudeMessagesMixedContentBlocks(t *testing.T) {
 	}
 }
 
+func TestNormalizeClaudeMessagesToolResultNonTextPayloadStringified(t *testing.T) {
+	msgs := []any{
+		map[string]any{
+			"role": "user",
+			"content": []any{
+				map[string]any{
+					"type":        "tool_result",
+					"tool_use_id": "call_image_1",
+					"name":        "vision_tool",
+					"content": []any{
+						map[string]any{"type": "text", "text": "image analysis"},
+						map[string]any{
+							"type":   "image",
+							"source": map[string]any{"type": "base64", "media_type": "image/png", "data": strings.Repeat("B", 2048)},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	got := normalizeClaudeMessages(msgs)
+	if len(got) != 1 {
+		t.Fatalf("expected one normalized message, got %d", len(got))
+	}
+	m := got[0].(map[string]any)
+	if m["role"] != "tool" {
+		t.Fatalf("expected tool role, got %#v", m["role"])
+	}
+	content, _ := m["content"].(string)
+	if !containsStr(content, `"type":"tool_result"`) || !containsStr(content, `"type":"image"`) {
+		t.Fatalf("expected non-text tool_result payload to be JSON stringified, got %q", content)
+	}
+	if !containsStr(content, omittedBinaryMarker) {
+		t.Fatalf("expected binary data to be sanitized with omitted marker, got %q", content)
+	}
+	if containsStr(content, strings.Repeat("B", 100)) {
+		t.Fatalf("expected raw base64 payload not to be included, got %q", content)
+	}
+}
+
 // ─── buildClaudeToolPrompt ───────────────────────────────────────────
 
 func TestBuildClaudeToolPromptSingleTool(t *testing.T) {

internal/adapter/claude/handler_utils.go

@@ -39,9 +39,15 @@ func normalizeClaudeMessages(messages []any) []any {
 						textParts = append(textParts, t)
 					}
 				case "tool_use":
-					flushText()
-					if toolMsg := normalizeClaudeToolUseToAssistant(b); toolMsg != nil {
-						out = append(out, toolMsg)
+					if role == "assistant" {
+						flushText()
+						if toolMsg := normalizeClaudeToolUseToAssistant(b); toolMsg != nil {
+							out = append(out, toolMsg)
+						}
+						continue
+					}
+					if raw := strings.TrimSpace(formatClaudeUnknownBlockForPrompt(b)); raw != "" {
+						textParts = append(textParts, raw)
 					}
 				case "tool_result":
 					flushText()
@@ -159,7 +165,7 @@ func normalizeClaudeToolResultToToolMessage(block map[string]any) map[string]any
 	out := map[string]any{
 		"role":         "tool",
 		"tool_call_id": toolCallID,
-		"content":      block["content"],
+		"content":      normalizeClaudeToolResultContent(block["content"]),
 	}
 	if name := strings.TrimSpace(fmt.Sprintf("%v", block["name"])); name != "" {
 		out["name"] = name
@@ -167,6 +173,21 @@ func normalizeClaudeToolResultToToolMessage(block map[string]any) map[string]any
 	return out
 }
 
+func normalizeClaudeToolResultContent(content any) any {
+	if text, ok := content.(string); ok {
+		return text
+	}
+	payload := map[string]any{
+		"type":    "tool_result",
+		"content": content,
+	}
+	b, err := json.Marshal(sanitizeClaudeBlockForPrompt(payload))
+	if err != nil {
+		return strings.TrimSpace(fmt.Sprintf("%v", content))
+	}
+	return string(b)
+}
+
 func formatClaudeBlockRaw(block map[string]any) string {
 	if block == nil {
 		return ""