feat(metadata): enhance metadata extraction with reasoning content support

internal/ai/compat/client.go

@@ -92,11 +92,18 @@ type chatMessage struct {
 
 type chatCompletionsResponse struct {
 	Choices []struct {
-		Message chatMessage `json:"message"`
+		Message responseChatMessage `json:"message"`
+		Text    string              `json:"text,omitempty"`
 	} `json:"choices"`
 	Error *providerError `json:"error,omitempty"`
 }
 
+type responseChatMessage struct {
+	Role             string          `json:"role"`
+	Content          json.RawMessage `json:"content"`
+	ReasoningContent string          `json:"reasoning_content,omitempty"`
+}
+
 type providerError struct {
 	Message string `json:"message"`
 	Type    string `json:"type,omitempty"`
@@ -200,7 +207,7 @@ func (c *Client) extractMetadataWithModel(ctx context.Context, input, model stri
 		return thoughttypes.ThoughtMetadata{}, fmt.Errorf("%s metadata: no choices returned", c.name)
 	}
 
-	rawResponse := resp.Choices[0].Message.Content
+	rawResponse := extractChoiceText(resp.Choices[0].Message, resp.Choices[0].Text)
 
 	if c.logConversations && c.log != nil {
 		c.log.Info("metadata conversation response",
@@ -247,7 +254,7 @@ func (c *Client) Summarize(ctx context.Context, systemPrompt, userPrompt string)
 		return "", fmt.Errorf("%s summarize: no choices returned", c.name)
 	}
 
-	return strings.TrimSpace(resp.Choices[0].Message.Content), nil
+	return extractChoiceText(resp.Choices[0].Message, resp.Choices[0].Text), nil
 }
 
 func (c *Client) Name() string {
@@ -335,12 +342,45 @@ func (c *Client) doJSON(ctx context.Context, path string, requestBody any, dest
 // extractJSONObject finds the first complete {...} block in s.
 // It handles models that prepend prose to a JSON response despite json_object mode.
 func extractJSONObject(s string) string {
-	start := strings.Index(s, "{")
-	end := strings.LastIndex(s, "}")
-	if start == -1 || end == -1 || end <= start {
-		return ""
+	for start := 0; start < len(s); start++ {
+		if s[start] != '{' {
+			continue
+		}
+		depth := 0
+		inString := false
+		escaped := false
+		for end := start; end < len(s); end++ {
+			ch := s[end]
+			if escaped {
+				escaped = false
+				continue
+			}
+			if ch == '\\' && inString {
+				escaped = true
+				continue
+			}
+			if ch == '"' {
+				inString = !inString
+				continue
+			}
+			if inString {
+				continue
+			}
+			switch ch {
+			case '{':
+				depth++
+			case '}':
+				depth--
+				if depth == 0 {
+					candidate := s[start : end+1]
+					if json.Valid([]byte(candidate)) {
+						return candidate
+					}
+				}
+			}
+		}
 	}
-	return s[start : end+1]
+	return ""
 }
 
 // stripThinkingBlocks removes <think>...</think> and <thinking>...</thinking>
@@ -379,6 +419,71 @@ func stripCodeFence(value string) string {
 	return strings.TrimSpace(value)
 }
 
+func extractChoiceText(message responseChatMessage, fallbackText string) string {
+	if text := strings.TrimSpace(extractMessageContent(message.Content)); text != "" {
+		return text
+	}
+	if text := strings.TrimSpace(message.ReasoningContent); text != "" {
+		return text
+	}
+	return strings.TrimSpace(fallbackText)
+}
+
+func extractMessageContent(raw json.RawMessage) string {
+	raw = bytes.TrimSpace(raw)
+	if len(raw) == 0 {
+		return ""
+	}
+
+	var contentString string
+	if err := json.Unmarshal(raw, &contentString); err == nil {
+		return contentString
+	}
+
+	var contentArray []any
+	if err := json.Unmarshal(raw, &contentArray); err == nil {
+		parts := make([]string, 0, len(contentArray))
+		for _, item := range contentArray {
+			if text := strings.TrimSpace(extractTextFromAny(item)); text != "" {
+				parts = append(parts, text)
+			}
+		}
+		return strings.Join(parts, "\n")
+	}
+
+	var contentObject map[string]any
+	if err := json.Unmarshal(raw, &contentObject); err == nil {
+		return extractTextFromAny(contentObject)
+	}
+
+	return strings.TrimSpace(string(raw))
+}
+
+func extractTextFromAny(value any) string {
+	switch typed := value.(type) {
+	case string:
+		return typed
+	case []any:
+		parts := make([]string, 0, len(typed))
+		for _, item := range typed {
+			if text := strings.TrimSpace(extractTextFromAny(item)); text != "" {
+				parts = append(parts, text)
+			}
+		}
+		return strings.Join(parts, "\n")
+	case map[string]any:
+		// Common provider shapes for chat content parts.
+		for _, key := range []string{"text", "output_text", "content", "value"} {
+			if nested, ok := typed[key]; ok {
+				if text := strings.TrimSpace(extractTextFromAny(nested)); text != "" {
+					return text
+				}
+			}
+		}
+	}
+	return ""
+}
+
 func isRetryableStatus(status int) bool {
 	switch status {
 	case http.StatusTooManyRequests, http.StatusInternalServerError, http.StatusBadGateway, http.StatusServiceUnavailable, http.StatusGatewayTimeout: