Files
sub2api/backend/internal/service/gateway_request.go
IanShaw027 87426e5dda fix(backend): 改进 thinking/tool block 签名处理和重试策略
主要改动:
- request_transformer: thinking block 缺少签名时降级为文本而非丢弃,保留内容并在上层禁用 thinking mode
- antigravity_gateway_service: 新增两阶段降级策略,先处理 thinking blocks,如仍失败且涉及 tool 签名错误则进一步降级 tool blocks
- gateway_request: 新增 FilterSignatureSensitiveBlocksForRetry 函数,支持将 tool_use/tool_result 降级为文本
- gateway_request: 改进 FilterThinkingBlocksForRetry,禁用顶层 thinking 配置以避免结构约束冲突
- gateway_service: 实现保守的两阶段重试逻辑,优先保留内容,仅在必要时降级工具调用
- 新增 antigravity_gateway_service_test.go 测试签名块剥离逻辑
- 更新相关测试用例以验证降级行为

此修复解决了跨平台/账户切换时历史消息签名失效导致的请求失败问题。
2026-01-04 22:32:36 +08:00

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package service
import (
"bytes"
"encoding/json"
"fmt"
)
// ParsedRequest 保存网关请求的预解析结果
//
// 性能优化说明:
// 原实现在多个位置重复解析请求体Handler、Service 各解析一次):
// 1. gateway_handler.go 解析获取 model 和 stream
// 2. gateway_service.go 再次解析获取 system、messages、metadata
// 3. GenerateSessionHash 又一次解析获取会话哈希所需字段
//
// 新实现一次解析,多处复用:
// 1. 在 Handler 层统一调用 ParseGatewayRequest 一次性解析
// 2. 将解析结果 ParsedRequest 传递给 Service 层
// 3. 避免重复 json.Unmarshal减少 CPU 和内存开销
type ParsedRequest struct {
Body []byte // 原始请求体(保留用于转发)
Model string // 请求的模型名称
Stream bool // 是否为流式请求
MetadataUserID string // metadata.user_id用于会话亲和
System any // system 字段内容
Messages []any // messages 数组
HasSystem bool // 是否包含 system 字段(包含 null 也视为显式传入)
}
// ParseGatewayRequest 解析网关请求体并返回结构化结果
// 性能优化:一次解析提取所有需要的字段,避免重复 Unmarshal
func ParseGatewayRequest(body []byte) (*ParsedRequest, error) {
var req map[string]any
if err := json.Unmarshal(body, &req); err != nil {
return nil, err
}
parsed := &ParsedRequest{
Body: body,
}
if rawModel, exists := req["model"]; exists {
model, ok := rawModel.(string)
if !ok {
return nil, fmt.Errorf("invalid model field type")
}
parsed.Model = model
}
if rawStream, exists := req["stream"]; exists {
stream, ok := rawStream.(bool)
if !ok {
return nil, fmt.Errorf("invalid stream field type")
}
parsed.Stream = stream
}
if metadata, ok := req["metadata"].(map[string]any); ok {
if userID, ok := metadata["user_id"].(string); ok {
parsed.MetadataUserID = userID
}
}
// system 字段只要存在就视为显式提供(即使为 null
// 以避免客户端传 null 时被默认 system 误注入。
if system, ok := req["system"]; ok {
parsed.HasSystem = true
parsed.System = system
}
if messages, ok := req["messages"].([]any); ok {
parsed.Messages = messages
}
return parsed, nil
}
// FilterThinkingBlocks removes thinking blocks from request body
// Returns filtered body or original body if filtering fails (fail-safe)
// This prevents 400 errors from invalid thinking block signatures
//
// Strategy:
// - When thinking.type != "enabled": Remove all thinking blocks
// - When thinking.type == "enabled": Only remove thinking blocks without valid signatures
// (blocks with missing/empty/dummy signatures that would cause 400 errors)
func FilterThinkingBlocks(body []byte) []byte {
return filterThinkingBlocksInternal(body, false)
}
// FilterThinkingBlocksForRetry strips thinking-related constructs for retry scenarios.
//
// Why:
// - Upstreams may reject historical `thinking`/`redacted_thinking` blocks due to invalid/missing signatures.
// - Anthropic extended thinking has a structural constraint: when top-level `thinking` is enabled and the
// final message is an assistant prefill, the assistant content must start with a thinking block.
// - If we remove thinking blocks but keep top-level `thinking` enabled, we can trigger:
// "Expected `thinking` or `redacted_thinking`, but found `text`"
//
// Strategy (B: preserve content as text):
// - Disable top-level `thinking` (remove `thinking` field).
// - Convert `thinking` blocks to `text` blocks (preserve the thinking content).
// - Remove `redacted_thinking` blocks (cannot be converted to text).
// - Ensure no message ends up with empty content.
func FilterThinkingBlocksForRetry(body []byte) []byte {
// Fast path: check for presence of thinking-related keys in messages or top-level thinking config.
if !bytes.Contains(body, []byte(`"type":"thinking"`)) &&
!bytes.Contains(body, []byte(`"type": "thinking"`)) &&
!bytes.Contains(body, []byte(`"type":"redacted_thinking"`)) &&
!bytes.Contains(body, []byte(`"type": "redacted_thinking"`)) &&
!bytes.Contains(body, []byte(`"thinking":`)) &&
!bytes.Contains(body, []byte(`"thinking" :`)) {
return body
}
var req map[string]any
if err := json.Unmarshal(body, &req); err != nil {
return body
}
modified := false
messages, ok := req["messages"].([]any)
if !ok {
return body
}
// Disable top-level thinking mode for retry to avoid structural/signature constraints upstream.
if _, exists := req["thinking"]; exists {
delete(req, "thinking")
modified = true
}
newMessages := make([]any, 0, len(messages))
for _, msg := range messages {
msgMap, ok := msg.(map[string]any)
if !ok {
newMessages = append(newMessages, msg)
continue
}
role, _ := msgMap["role"].(string)
content, ok := msgMap["content"].([]any)
if !ok {
// String content or other format - keep as is
newMessages = append(newMessages, msg)
continue
}
newContent := make([]any, 0, len(content))
modifiedThisMsg := false
for _, block := range content {
blockMap, ok := block.(map[string]any)
if !ok {
newContent = append(newContent, block)
continue
}
blockType, _ := blockMap["type"].(string)
// Convert thinking blocks to text (preserve content) and drop redacted_thinking.
switch blockType {
case "thinking":
modifiedThisMsg = true
thinkingText, _ := blockMap["thinking"].(string)
if thinkingText == "" {
continue
}
newContent = append(newContent, map[string]any{
"type": "text",
"text": thinkingText,
})
continue
case "redacted_thinking":
modifiedThisMsg = true
continue
}
// Handle blocks without type discriminator but with a "thinking" field.
if blockType == "" {
if rawThinking, hasThinking := blockMap["thinking"]; hasThinking {
modifiedThisMsg = true
switch v := rawThinking.(type) {
case string:
if v != "" {
newContent = append(newContent, map[string]any{"type": "text", "text": v})
}
default:
if b, err := json.Marshal(v); err == nil && len(b) > 0 {
newContent = append(newContent, map[string]any{"type": "text", "text": string(b)})
}
}
continue
}
}
newContent = append(newContent, block)
}
if modifiedThisMsg {
modified = true
// Handle empty content after filtering
if len(newContent) == 0 {
// Always add a placeholder to avoid upstream "non-empty content" errors.
placeholder := "(content removed)"
if role == "assistant" {
placeholder = "(assistant content removed)"
}
newContent = append(newContent, map[string]any{
"type": "text",
"text": placeholder,
})
}
msgMap["content"] = newContent
}
newMessages = append(newMessages, msgMap)
}
if modified {
req["messages"] = newMessages
} else {
// Avoid rewriting JSON when no changes are needed.
return body
}
newBody, err := json.Marshal(req)
if err != nil {
return body
}
return newBody
}
// FilterSignatureSensitiveBlocksForRetry is a stronger retry filter for cases where upstream errors indicate
// signature/thought_signature validation issues involving tool blocks.
//
// This performs everything in FilterThinkingBlocksForRetry, plus:
// - Convert `tool_use` blocks to text (name/id/input) so we stop sending structured tool calls.
// - Convert `tool_result` blocks to text so we keep tool results visible without tool semantics.
//
// Use this only when needed: converting tool blocks to text changes model behaviour and can increase the
// risk of prompt injection (tool output becomes plain conversation text).
func FilterSignatureSensitiveBlocksForRetry(body []byte) []byte {
// Fast path: only run when we see likely relevant constructs.
if !bytes.Contains(body, []byte(`"type":"thinking"`)) &&
!bytes.Contains(body, []byte(`"type": "thinking"`)) &&
!bytes.Contains(body, []byte(`"type":"redacted_thinking"`)) &&
!bytes.Contains(body, []byte(`"type": "redacted_thinking"`)) &&
!bytes.Contains(body, []byte(`"type":"tool_use"`)) &&
!bytes.Contains(body, []byte(`"type": "tool_use"`)) &&
!bytes.Contains(body, []byte(`"type":"tool_result"`)) &&
!bytes.Contains(body, []byte(`"type": "tool_result"`)) &&
!bytes.Contains(body, []byte(`"thinking":`)) &&
!bytes.Contains(body, []byte(`"thinking" :`)) {
return body
}
var req map[string]any
if err := json.Unmarshal(body, &req); err != nil {
return body
}
modified := false
// Disable top-level thinking for retry to avoid structural/signature constraints upstream.
if _, exists := req["thinking"]; exists {
delete(req, "thinking")
modified = true
}
messages, ok := req["messages"].([]any)
if !ok {
return body
}
newMessages := make([]any, 0, len(messages))
for _, msg := range messages {
msgMap, ok := msg.(map[string]any)
if !ok {
newMessages = append(newMessages, msg)
continue
}
role, _ := msgMap["role"].(string)
content, ok := msgMap["content"].([]any)
if !ok {
newMessages = append(newMessages, msg)
continue
}
newContent := make([]any, 0, len(content))
modifiedThisMsg := false
for _, block := range content {
blockMap, ok := block.(map[string]any)
if !ok {
newContent = append(newContent, block)
continue
}
blockType, _ := blockMap["type"].(string)
switch blockType {
case "thinking":
modifiedThisMsg = true
thinkingText, _ := blockMap["thinking"].(string)
if thinkingText == "" {
continue
}
newContent = append(newContent, map[string]any{"type": "text", "text": thinkingText})
continue
case "redacted_thinking":
modifiedThisMsg = true
continue
case "tool_use":
modifiedThisMsg = true
name, _ := blockMap["name"].(string)
id, _ := blockMap["id"].(string)
input := blockMap["input"]
inputJSON, _ := json.Marshal(input)
text := "(tool_use)"
if name != "" {
text += " name=" + name
}
if id != "" {
text += " id=" + id
}
if len(inputJSON) > 0 && string(inputJSON) != "null" {
text += " input=" + string(inputJSON)
}
newContent = append(newContent, map[string]any{"type": "text", "text": text})
continue
case "tool_result":
modifiedThisMsg = true
toolUseID, _ := blockMap["tool_use_id"].(string)
isError, _ := blockMap["is_error"].(bool)
content := blockMap["content"]
contentJSON, _ := json.Marshal(content)
text := "(tool_result)"
if toolUseID != "" {
text += " tool_use_id=" + toolUseID
}
if isError {
text += " is_error=true"
}
if len(contentJSON) > 0 && string(contentJSON) != "null" {
text += "\n" + string(contentJSON)
}
newContent = append(newContent, map[string]any{"type": "text", "text": text})
continue
}
if blockType == "" {
if rawThinking, hasThinking := blockMap["thinking"]; hasThinking {
modifiedThisMsg = true
switch v := rawThinking.(type) {
case string:
if v != "" {
newContent = append(newContent, map[string]any{"type": "text", "text": v})
}
default:
if b, err := json.Marshal(v); err == nil && len(b) > 0 {
newContent = append(newContent, map[string]any{"type": "text", "text": string(b)})
}
}
continue
}
}
newContent = append(newContent, block)
}
if modifiedThisMsg {
modified = true
if len(newContent) == 0 {
placeholder := "(content removed)"
if role == "assistant" {
placeholder = "(assistant content removed)"
}
newContent = append(newContent, map[string]any{"type": "text", "text": placeholder})
}
msgMap["content"] = newContent
}
newMessages = append(newMessages, msgMap)
}
if !modified {
return body
}
req["messages"] = newMessages
newBody, err := json.Marshal(req)
if err != nil {
return body
}
return newBody
}
// filterThinkingBlocksInternal removes invalid thinking blocks from request
// Strategy:
// - When thinking.type != "enabled": Remove all thinking blocks
// - When thinking.type == "enabled": Only remove thinking blocks without valid signatures
func filterThinkingBlocksInternal(body []byte, _ bool) []byte {
// Fast path: if body doesn't contain "thinking", skip parsing
if !bytes.Contains(body, []byte(`"type":"thinking"`)) &&
!bytes.Contains(body, []byte(`"type": "thinking"`)) &&
!bytes.Contains(body, []byte(`"type":"redacted_thinking"`)) &&
!bytes.Contains(body, []byte(`"type": "redacted_thinking"`)) &&
!bytes.Contains(body, []byte(`"thinking":`)) &&
!bytes.Contains(body, []byte(`"thinking" :`)) {
return body
}
var req map[string]any
if err := json.Unmarshal(body, &req); err != nil {
return body
}
// Check if thinking is enabled
thinkingEnabled := false
if thinking, ok := req["thinking"].(map[string]any); ok {
if thinkType, ok := thinking["type"].(string); ok && thinkType == "enabled" {
thinkingEnabled = true
}
}
messages, ok := req["messages"].([]any)
if !ok {
return body
}
filtered := false
for _, msg := range messages {
msgMap, ok := msg.(map[string]any)
if !ok {
continue
}
role, _ := msgMap["role"].(string)
content, ok := msgMap["content"].([]any)
if !ok {
continue
}
newContent := make([]any, 0, len(content))
filteredThisMessage := false
for _, block := range content {
blockMap, ok := block.(map[string]any)
if !ok {
newContent = append(newContent, block)
continue
}
blockType, _ := blockMap["type"].(string)
if blockType == "thinking" || blockType == "redacted_thinking" {
// When thinking is enabled and this is an assistant message,
// only keep thinking blocks with valid signatures
if thinkingEnabled && role == "assistant" {
signature, _ := blockMap["signature"].(string)
if signature != "" && signature != "skip_thought_signature_validator" {
newContent = append(newContent, block)
continue
}
}
filtered = true
filteredThisMessage = true
continue
}
// Handle blocks without type discriminator but with "thinking" key
if blockType == "" {
if _, hasThinking := blockMap["thinking"]; hasThinking {
filtered = true
filteredThisMessage = true
continue
}
}
newContent = append(newContent, block)
}
if filteredThisMessage {
msgMap["content"] = newContent
}
}
if !filtered {
return body
}
newBody, err := json.Marshal(req)
if err != nil {
return body
}
return newBody
}