feat(providers): parse XML tool calls as fallback for minimax

When the provider returns no structured tool_calls but Content contains
XML blocks like <minimax:toolcall>, extract and parse them into ToolCall
structs. This handles cases where minimax returns tool calls only as XML.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/providers/claude_cli_provider_test.go

@@ -979,3 +979,89 @@ func TestFindMatchingBrace(t *testing.T) {
 		}
 	}
 }
+
+// --- XML tool call extract/strip tests ---
+
+func TestExtractXMLToolCalls_Single(t *testing.T) {
+	text := `<minimax:toolcall>
+<invoke name="exec">
+<parameter name="command">echo hello</parameter>
+</invoke>
+</minimax:toolcall>`
+
+	calls := extractXMLToolCalls(text)
+	if len(calls) != 1 {
+		t.Fatalf("expected 1 tool call, got %d", len(calls))
+	}
+	if calls[0].Name != "exec" {
+		t.Errorf("Name = %q, want %q", calls[0].Name, "exec")
+	}
+	if calls[0].Arguments["command"] != "echo hello" {
+		t.Errorf("Arguments[command] = %v, want %q", calls[0].Arguments["command"], "echo hello")
+	}
+	if calls[0].Function == nil || calls[0].Function.Name != "exec" {
+		t.Errorf("Function.Name should be exec")
+	}
+}
+
+func TestExtractXMLToolCalls_Multiple(t *testing.T) {
+	text := `<minimax:toolcall>
+<invoke name="web_search">
+<parameter name="query">golang testing</parameter>
+</invoke>
+<invoke name="exec">
+<parameter name="command">go test ./...</parameter>
+<parameter name="timeout">30</parameter>
+</invoke>
+</minimax:toolcall>`
+
+	calls := extractXMLToolCalls(text)
+	if len(calls) != 2 {
+		t.Fatalf("expected 2 tool calls, got %d", len(calls))
+	}
+	if calls[0].Name != "web_search" {
+		t.Errorf("[0].Name = %q, want %q", calls[0].Name, "web_search")
+	}
+	if calls[1].Name != "exec" {
+		t.Errorf("[1].Name = %q, want %q", calls[1].Name, "exec")
+	}
+	if calls[1].Arguments["timeout"] != "30" {
+		t.Errorf("[1].Arguments[timeout] = %v, want %q", calls[1].Arguments["timeout"], "30")
+	}
+}
+
+func TestExtractXMLToolCalls_NoXML(t *testing.T) {
+	calls := extractXMLToolCalls("just regular text")
+	if len(calls) != 0 {
+		t.Errorf("expected 0 tool calls, got %d", len(calls))
+	}
+}
+
+func TestStripXMLToolCalls(t *testing.T) {
+	text := `Let me run that.
+<minimax:toolcall>
+<invoke name="exec">
+<parameter name="command">echo hello</parameter>
+</invoke>
+</minimax:toolcall>
+Done.`
+
+	got := stripXMLToolCalls(text)
+	if strings.Contains(got, "toolcall") {
+		t.Errorf("should remove XML block, got %q", got)
+	}
+	if !strings.Contains(got, "Let me run that.") {
+		t.Errorf("should keep text before, got %q", got)
+	}
+	if !strings.Contains(got, "Done.") {
+		t.Errorf("should keep text after, got %q", got)
+	}
+}
+
+func TestStripXMLToolCalls_NoXML(t *testing.T) {
+	text := "Just regular text."
+	got := stripXMLToolCalls(text)
+	if got != text {
+		t.Errorf("stripXMLToolCalls() = %q, want %q", got, text)
+	}
+}

pkg/providers/http_provider.go

@@ -27,8 +27,14 @@ func (p *HTTPProvider) Chat(ctx context.Context, messages []Message, tools []Too
 	if err != nil {
 		return nil, err
 	}
-	// Strip provider-specific XML tool call artifacts (e.g. minimax)
+	// If provider returned no structured tool_calls but Content has XML
-	// that leak into Content alongside structured tool_calls.
+	// tool call blocks (e.g. minimax), parse them as a fallback.
+	if len(resp.ToolCalls) == 0 {
+		if xmlCalls := extractXMLToolCalls(resp.Content); len(xmlCalls) > 0 {
+			resp.ToolCalls = xmlCalls
+		}
+	}
+	// Strip XML tool call artifacts from Content regardless.
 	resp.Content = stripXMLToolCalls(resp.Content)
 	return resp, nil
 }

pkg/providers/tool_call_extract.go

@@ -2,6 +2,7 @@ package providers
 
 import (
 	"encoding/json"
+	"fmt"
 	"strings"
 )
 
@@ -56,6 +57,122 @@ func extractToolCallsFromText(text string) []ToolCall {
 	return result
 }
 
+// extractXMLToolCalls parses XML tool call blocks (e.g. <minimax:toolcall>)
+// into structured ToolCall objects. Used as a fallback when the provider returns
+// tool calls as XML in Content but not in the structured tool_calls field.
+//
+// Expected format:
+//
+//	<vendor:toolcall>
+//	<invoke name="tool_name">
+//	<parameter name="param">value</parameter>
+//	</invoke>
+//	</vendor:toolcall>
+func extractXMLToolCalls(text string) []ToolCall {
+	var result []ToolCall
+	remaining := text
+	callIdx := 0
+
+	for {
+		// Find next :toolcall> block
+		idx := strings.Index(remaining, ":toolcall>")
+		if idx == -1 {
+			break
+		}
+		tagStart := strings.LastIndex(remaining[:idx], "<")
+		if tagStart == -1 {
+			break
+		}
+		ns := remaining[tagStart+1 : idx]
+		closeTag := "</" + ns + ":toolcall>"
+		closeIdx := strings.Index(remaining, closeTag)
+		if closeIdx == -1 {
+			break
+		}
+
+		block := remaining[idx+len(":toolcall>") : closeIdx]
+		remaining = remaining[closeIdx+len(closeTag):]
+
+		// Parse <invoke> elements within the block
+		invokeRemaining := block
+		for {
+			invokeStart := strings.Index(invokeRemaining, "<invoke")
+			if invokeStart == -1 {
+				break
+			}
+			invokeEnd := strings.Index(invokeRemaining[invokeStart:], "</invoke>")
+			if invokeEnd == -1 {
+				break
+			}
+			invokeBody := invokeRemaining[invokeStart : invokeStart+invokeEnd+len("</invoke>")]
+			invokeRemaining = invokeRemaining[invokeStart+invokeEnd+len("</invoke>"):]
+
+			// Extract tool name from <invoke name="...">
+			nameStart := strings.Index(invokeBody, `name="`)
+			if nameStart == -1 {
+				continue
+			}
+			nameStart += len(`name="`)
+			nameEnd := strings.Index(invokeBody[nameStart:], `"`)
+			if nameEnd == -1 {
+				continue
+			}
+			toolName := invokeBody[nameStart : nameStart+nameEnd]
+
+			// Extract parameters
+			args := make(map[string]interface{})
+			paramRemaining := invokeBody
+			for {
+				pStart := strings.Index(paramRemaining, "<parameter")
+				if pStart == -1 {
+					break
+				}
+				pNameStart := strings.Index(paramRemaining[pStart:], `name="`)
+				if pNameStart == -1 {
+					break
+				}
+				pNameStart += pStart + len(`name="`)
+				pNameEnd := strings.Index(paramRemaining[pNameStart:], `"`)
+				if pNameEnd == -1 {
+					break
+				}
+				paramName := paramRemaining[pNameStart : pNameStart+pNameEnd]
+
+				// Find closing > of the <parameter ...> tag
+				tagClose := strings.Index(paramRemaining[pNameStart:], ">")
+				if tagClose == -1 {
+					break
+				}
+				valueStart := pNameStart + tagClose + 1
+				valueEnd := strings.Index(paramRemaining[valueStart:], "</parameter>")
+				if valueEnd == -1 {
+					break
+				}
+				paramValue := paramRemaining[valueStart : valueStart+valueEnd]
+				args[paramName] = paramValue
+				paramRemaining = paramRemaining[valueStart+valueEnd+len("</parameter>"):]
+			}
+
+			// Build Arguments JSON string
+			argsJSON, _ := json.Marshal(args)
+
+			callIdx++
+			result = append(result, ToolCall{
+				ID:        fmt.Sprintf("xmltc_%d", callIdx),
+				Type:      "function",
+				Name:      toolName,
+				Arguments: args,
+				Function: &FunctionCall{
+					Name:      toolName,
+					Arguments: string(argsJSON),
+				},
+			})
+		}
+	}
+
+	return result
+}
+
 // stripXMLToolCalls removes XML tool call blocks (e.g. <minimax:toolcall>...</minimax:toolcall>)
 // from response text. Some providers embed raw XML tool calls in Content alongside
 // structured tool_calls; this prevents them from leaking to users.