feat: integrate reasoning content into assistant tool-call messages and improve tool markup parsing for prompt compatibility

internal/httpapi/gemini/convert_messages.go

@@ -44,14 +44,20 @@ func geminiMessagesFromRequest(req map[string]any) []any {
 		}
 
 		textParts := make([]string, 0, len(parts))
+		pendingThinking := ""
 		flushText := func() {
 			if len(textParts) == 0 {
 				return
 			}
-			out = append(out, map[string]any{
+			msg := map[string]any{
 				"role":    role,
 				"content": strings.Join(textParts, "\n"),
-			})
+			}
+			if role == "assistant" && strings.TrimSpace(pendingThinking) != "" {
+				msg["reasoning_content"] = pendingThinking
+				pendingThinking = ""
+			}
+			out = append(out, msg)
 			textParts = textParts[:0]
 		}
 
@@ -61,6 +67,14 @@ func geminiMessagesFromRequest(req map[string]any) []any {
 				continue
 			}
 			if text := strings.TrimSpace(asString(part["text"])); text != "" {
+				if role == "assistant" && isGeminiThoughtPart(part) {
+					if pendingThinking == "" {
+						pendingThinking = text
+					} else {
+						pendingThinking += "\n" + text
+					}
+					continue
+				}
 				textParts = append(textParts, text)
 				continue
 			}
@@ -75,7 +89,7 @@ func geminiMessagesFromRequest(req map[string]any) []any {
 						}
 					}
 					lastToolCallIDByName[strings.ToLower(name)] = callID
-					out = append(out, map[string]any{
+					msg := map[string]any{
 						"role": "assistant",
 						"tool_calls": []any{
 							map[string]any{
@@ -87,7 +101,12 @@ func geminiMessagesFromRequest(req map[string]any) []any {
 								},
 							},
 						},
-					})
+					}
+					if strings.TrimSpace(pendingThinking) != "" {
+						msg["reasoning_content"] = pendingThinking
+						pendingThinking = ""
+					}
+					out = append(out, msg)
 				}
 				continue
 			}
@@ -132,10 +151,29 @@ func geminiMessagesFromRequest(req map[string]any) []any {
 			}
 		}
 		flushText()
+		if role == "assistant" && strings.TrimSpace(pendingThinking) != "" {
+			out = append(out, map[string]any{
+				"role":              "assistant",
+				"reasoning_content": pendingThinking,
+			})
+		}
 	}
 	return out
 }
 
+func isGeminiThoughtPart(part map[string]any) bool {
+	if part == nil {
+		return false
+	}
+	if v, ok := part["thought"].(bool); ok {
+		return v
+	}
+	if v, ok := part["thoughtSignature"].(string); ok && strings.TrimSpace(v) != "" {
+		return true
+	}
+	return false
+}
+
 func normalizeGeminiSystemInstruction(raw any) string {
 	switch v := raw.(type) {
 	case string:

internal/httpapi/gemini/convert_messages_test.go

@@ -1,6 +1,7 @@
 package gemini
 
 import (
+	"ds2api/internal/promptcompat"
 	"strings"
 	"testing"
 )
@@ -53,6 +54,46 @@ func TestGeminiMessagesFromRequestPreservesFunctionRoundtrip(t *testing.T) {
 	}
 }
 
+func TestGeminiMessagesFromRequestPreservesThoughtOnFunctionCallHistory(t *testing.T) {
+	req := map[string]any{
+		"contents": []any{
+			map[string]any{
+				"role": "model",
+				"parts": []any{
+					map[string]any{"text": "need current state before answering", "thought": true},
+					map[string]any{
+						"functionCall": map[string]any{
+							"id":   "call_g1",
+							"name": "search_web",
+							"args": map[string]any{"query": "ai"},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	got := geminiMessagesFromRequest(req)
+	if len(got) != 1 {
+		t.Fatalf("expected one normalized message, got %#v", got)
+	}
+	assistant, _ := got[0].(map[string]any)
+	if assistant["reasoning_content"] != "need current state before answering" {
+		t.Fatalf("expected thought preserved as reasoning_content, got %#v", assistant)
+	}
+	tc, _ := assistant["tool_calls"].([]any)
+	if len(tc) != 1 {
+		t.Fatalf("expected one tool call, got %#v", assistant["tool_calls"])
+	}
+	prompt, _ := promptcompat.BuildOpenAIPromptForAdapter(got, nil, "", true)
+	if !strings.Contains(prompt, "[reasoning_content]\nneed current state before answering\n[/reasoning_content]") {
+		t.Fatalf("expected thought in prompt history, got %q", prompt)
+	}
+	if !strings.Contains(prompt, `<|DSML|invoke name="search_web">`) {
+		t.Fatalf("expected tool call in prompt history, got %q", prompt)
+	}
+}
+
 func TestGeminiMessagesFromRequestPreservesUnknownPartAsRawJSONText(t *testing.T) {
 	req := map[string]any{
 		"contents": []any{