fix(toolcall): fix deepseek function calling bug and add json repair

- Fix: Expand stream sieve keywords to support function.name: and [TOOL_CALL_HISTORY]

- Fix: Add repairInvalidJSONBackslashes to handle unescaped backslashes in Windows paths

- Sync: Update JS stream sieve to match Go implementation

- Test: Add unit tests for backslash repair and deepseek format parsing

- Tool: Move repair json test tool to tests/repair_json_tool.go

internal/util/toolcalls_parse.go

@@ -264,6 +264,13 @@ func parseToolCallInput(v any) map[string]any {
 		if err := json.Unmarshal([]byte(raw), &parsed); err == nil && parsed != nil {
 			return parsed
 		}
+		// Try to repair invalid backslashes (common in Windows paths output by models)
+		repaired := repairInvalidJSONBackslashes(raw)
+		if repaired != raw {
+			if err := json.Unmarshal([]byte(repaired), &parsed); err == nil && parsed != nil {
+				return parsed
+			}
+		}
 		return map[string]any{"_raw": raw}
 	default:
 		b, err := json.Marshal(x)
@@ -277,3 +284,51 @@ func parseToolCallInput(v any) map[string]any {
 		return map[string]any{}
 	}
 }
+
+func repairInvalidJSONBackslashes(s string) string {
+	if !strings.Contains(s, "\\") {
+		return s
+	}
+	var out strings.Builder
+	out.Grow(len(s) + 10)
+	runes := []rune(s)
+	for i := 0; i < len(runes); i++ {
+		if runes[i] == '\\' {
+			if i+1 < len(runes) {
+				next := runes[i+1]
+				switch next {
+				case '"', '\\', '/', 'b', 'f', 'n', 'r', 't':
+					out.WriteRune('\\')
+					out.WriteRune(next)
+					i++
+					continue
+				case 'u':
+					if i+5 < len(runes) {
+						isHex := true
+						for j := 1; j <= 4; j++ {
+							r := runes[i+1+j]
+							if !((r >= '0' && r <= '9') || (r >= 'a' && r <= 'f') || (r >= 'A' && r <= 'F')) {
+								isHex = false
+								break
+							}
+						}
+						if isHex {
+							out.WriteRune('\\')
+							out.WriteRune('u')
+							for j := 1; j <= 4; j++ {
+								out.WriteRune(runes[i+1+j])
+							}
+							i += 5
+							continue
+						}
+					}
+				}
+			}
+			// Not a valid escape sequence, double it
+			out.WriteString("\\\\")
+		} else {
+			out.WriteRune(runes[i])
+		}
+	}
+	return out.String()
+}