模型支持协议扩展参数，用于关闭思考模式

DeepSeek 现役的 v4 系列全部默认开启思考模式，没有单独的非思考型模型
可换；官方给的关闭方式是在请求里带 thinking={"type":"disabled"}。

ai_models 表早有 extra_json 字段但从未接线，这里接通：模型配置里的
JSON 对象会合并进每次调用的请求体，因此任何协议级参数都能在管理端
配置，不必改代码。合并不会覆盖 model/messages/max_tokens/temperature/
stream —— 预算和结构由代码掌握，重试逻辑才不会被配置绕过。
写入前校验 JSON，避免非法值存进 JSON 列后每次调用才报错。

线上模型已配置为关闭思考：同一会话下由 10133 ms / 1024 输出 tokens、
回复被截断，变为 669 ms / 10 tokens、回复完整。max_tokens 相应回调至 512。

管理端模型表单新增「协议参数」输入框（该目录尚未纳入版本库，仅已发布）。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

im/backend/internal/app/admin_ai.go

@@ -5,6 +5,7 @@ import (
 	"crypto/sha256"
 	"database/sql"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/http"
@@ -27,18 +28,44 @@ type aiModelRequest struct {
 	TimeoutMS   *int     `json:"timeoutMs"`
 	Status      *int     `json:"status"`
 	IsDefault   *bool    `json:"isDefault"`
+	// Raw provider fields merged into every call, e.g. {"thinking":{"type":"disabled"}}
+	// to stop a model that reasons by default from spending the budget thinking.
+	Extra *string `json:"extra"`
 }
 
-const aiModelColumns = `id,name,protocol,base_url,model_name,api_key_cipher,temperature,max_tokens,timeout_ms,status,is_default,created_at,updated_at`
+// The column is JSON, so an invalid value has to be refused before it is stored
+// and starts failing every call at read time instead.
+func aiModelExtra(value *string, fallback any) (any, error) {
+	if value == nil {
+		return fallback, nil
+	}
+	trimmed := strings.TrimSpace(*value)
+	if trimmed == "" {
+		return nil, nil
+	}
+	var parsed map[string]any
+	if err := json.Unmarshal([]byte(trimmed), &parsed); err != nil {
+		return nil, fmt.Errorf("扩展参数必须是 JSON 对象")
+	}
+	return trimmed, nil
+}
+
+const aiModelColumns = `id,name,protocol,base_url,model_name,api_key_cipher,temperature,max_tokens,timeout_ms,status,is_default,extra_json,created_at,updated_at`
 
 func (a *App) scanAIModel(scan func(dest ...any) error) (aiModel, error) {
 	var model aiModel
 	var cipher string
+	var extra sql.NullString
 	var created, updated time.Time
 	if err := scan(&model.ID, &model.Name, &model.Protocol, &model.BaseURL, &model.ModelName, &cipher,
-		&model.Temperature, &model.MaxTokens, &model.TimeoutMS, &model.Status, &model.IsDefault, &created, &updated); err != nil {
+		&model.Temperature, &model.MaxTokens, &model.TimeoutMS, &model.Status, &model.IsDefault, &extra, &created, &updated); err != nil {
 		return aiModel{}, err
 	}
+	if strings.TrimSpace(extra.String) != "" {
+		if err := json.Unmarshal([]byte(extra.String), &model.Extra); err != nil {
+			return model, fmt.Errorf("模型 %s 的扩展参数不是合法 JSON", model.Name)
+		}
+	}
 	model.HasAPIKey = cipher != ""
 	if cipher != "" {
 		plain, err := a.decryptSecret(cipher)
@@ -187,6 +214,11 @@ func (a *App) adminCreateAIModel(w http.ResponseWriter, r *http.Request) {
 		status = *req.Status
 	}
 	isDefault := req.IsDefault != nil && *req.IsDefault
+	extra, err := aiModelExtra(req.Extra, nil)
+	if err != nil {
+		fail(w, http.StatusBadRequest, 20001, err.Error())
+		return
+	}
 	tx, err := a.db.BeginTx(r.Context(), nil)
 	if err != nil {
 		fail(w, http.StatusInternalServerError, 50001, "保存模型失败")
@@ -200,9 +232,9 @@ func (a *App) adminCreateAIModel(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 	result, err := tx.ExecContext(r.Context(), `INSERT INTO ai_models
-		(name,protocol,base_url,model_name,api_key_cipher,temperature,max_tokens,timeout_ms,status,is_default)
-		VALUES(?,?,?,?,?,?,?,?,?,?)`,
-		req.Name, req.Protocol, req.BaseURL, req.ModelName, cipher, temperature, maxTokens, timeout, status, btoi(isDefault))
+		(name,protocol,base_url,model_name,api_key_cipher,temperature,max_tokens,timeout_ms,status,is_default,extra_json)
+		VALUES(?,?,?,?,?,?,?,?,?,?,?)`,
+		req.Name, req.Protocol, req.BaseURL, req.ModelName, cipher, temperature, maxTokens, timeout, status, btoi(isDefault), extra)
 	if err != nil {
 		if isDuplicateAIModelName(err) {
 			fail(w, http.StatusBadRequest, 20001, "模型名称已存在")
@@ -270,6 +302,16 @@ func (a *App) adminUpdateAIModel(w http.ResponseWriter, r *http.Request) {
 	if req.IsDefault != nil {
 		isDefault = *req.IsDefault
 	}
+	var existingExtra any
+	if len(existing.Extra) > 0 {
+		encoded, _ := json.Marshal(existing.Extra)
+		existingExtra = string(encoded)
+	}
+	extra, err := aiModelExtra(req.Extra, existingExtra)
+	if err != nil {
+		fail(w, http.StatusBadRequest, 20001, err.Error())
+		return
+	}
 	tx, err := a.db.BeginTx(r.Context(), nil)
 	if err != nil {
 		fail(w, http.StatusInternalServerError, 50001, "保存模型失败")
@@ -282,9 +324,9 @@ func (a *App) adminUpdateAIModel(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 	}
-	args := append([]any{req.Name, req.Protocol, req.BaseURL, req.ModelName, temperature, maxTokens, timeout, status, btoi(isDefault)}, cipherArgs...)
+	args := append([]any{req.Name, req.Protocol, req.BaseURL, req.ModelName, temperature, maxTokens, timeout, status, btoi(isDefault), extra}, cipherArgs...)
 	args = append(args, id)
-	if _, err = tx.ExecContext(r.Context(), `UPDATE ai_models SET name=?,protocol=?,base_url=?,model_name=?,temperature=?,max_tokens=?,timeout_ms=?,status=?,is_default=?`+cipherClause+` WHERE id=?`, args...); err != nil {
+	if _, err = tx.ExecContext(r.Context(), `UPDATE ai_models SET name=?,protocol=?,base_url=?,model_name=?,temperature=?,max_tokens=?,timeout_ms=?,status=?,is_default=?,extra_json=?`+cipherClause+` WHERE id=?`, args...); err != nil {
 		if isDuplicateAIModelName(err) {
 			fail(w, http.StatusBadRequest, 20001, "模型名称已存在")
 			return