feat(antigravity): configurable signature cache with bypass-mode validation

Antigravity 的 Claude thinking signature 处理新增 cache/bypass 双模式，并为 bypass 模式实现按 SIGNATURE-CHANNEL-SPEC.md 的签名校验。新增 antigravity-signature-cache-enabled 配置项（默认 true）： - cache mode（true）：使用服务端缓存的签名，行为与原有逻辑完全一致 - bypass mode（false）：直接使用客户端提供的签名，经过校验和归一化支持配置热重载，运行时可切换模式。校验流程： 1. 剥离历史 cache-mode 的 'modelGroup#' 前缀（如 claude#Exxxx → Exxxx） 2. 首字符必须为 'E'（单层编码）或 'R'（双层编码），否则拒绝 3. R 开头：base64 解码 → 内层必须以 'E' 开头 → 继续单层校验 4. E 开头：base64 解码 → 首字节必须为 0x12（Claude protobuf 标识） 5. 所有合法签名归一化为 R 形式（双层 base64）发往 Antigravity 后端非法签名处理策略： - 非严格模式（默认）：translator 静默丢弃无签名的 thinking block - 严格模式（antigravity-signature-bypass-strict: true）： executor 层在请求发往上游前直接返回 HTTP 400 按 SIGNATURE-CHANNEL-SPEC.md 解析 Claude 签名的完整 protobuf 结构： - Top-level Field 2（容器）→ Field 1（渠道块） - 渠道块提取：channel_id (Field 1)、infrastructure (Field 2)、 model_text (Field 6)、field7 (Field 7) - 计算 routing_class、infrastructure_class、schema_features - 使用 google.golang.org/protobuf/encoding/protowire 解析 - resolveThinkingSignature 拆分为 resolveCacheModeSignature / resolveBypassModeSignature - hasResolvedThinkingSignature：mode-aware 签名有效性判断（cache: len>=50 via HasValidSignature，bypass: non-empty） - validateAntigravityRequestSignatures：executor 预检，仅在 bypass + strict 模式下拦截非法签名返回 400 - 响应侧签名缓存逻辑与 cache mode 集成 - Cache mode 行为完全保留：无 '#' 前缀的原生签名静默丢弃
2026-03-31 14:15:06 +08:00
parent 1dba2d0f81
commit cf249586a9
11 changed files with 1494 additions and 62 deletions
@@ -17,6 +17,56 @@ import (
 	"github.com/tidwall/sjson"
 )

+func resolveThinkingSignature(modelName, thinkingText, rawSignature string) string {
+	if cache.SignatureCacheEnabled() {
+		return resolveCacheModeSignature(modelName, thinkingText, rawSignature)
+	}
+	return resolveBypassModeSignature(rawSignature)
+}
+
+func resolveCacheModeSignature(modelName, thinkingText, rawSignature string) string {
+	if thinkingText != "" {
+		if cachedSig := cache.GetCachedSignature(modelName, thinkingText); cachedSig != "" {
+			return cachedSig
+		}
+	}
+
+	if rawSignature == "" {
+		return ""
+	}
+
+	clientSignature := ""
+	arrayClientSignatures := strings.SplitN(rawSignature, "#", 2)
+	if len(arrayClientSignatures) == 2 {
+		if cache.GetModelGroup(modelName) == arrayClientSignatures[0] {
+			clientSignature = arrayClientSignatures[1]
+		}
+	}
+	if cache.HasValidSignature(modelName, clientSignature) {
+		return clientSignature
+	}
+
+	return ""
+}
+
+func resolveBypassModeSignature(rawSignature string) string {
+	if rawSignature == "" {
+		return ""
+	}
+	normalized, err := normalizeClaudeBypassSignature(rawSignature)
+	if err != nil {
+		return ""
+	}
+	return normalized
+}
+
+func hasResolvedThinkingSignature(modelName, signature string) bool {
+	if cache.SignatureCacheEnabled() {
+		return cache.HasValidSignature(modelName, signature)
+	}
+	return signature != ""
+}
+
 // ConvertClaudeRequestToAntigravity parses and transforms a Claude Code API request into Gemini CLI API format.
 // It extracts the model name, system instruction, message contents, and tool declarations
 // from the raw JSON request and returns them in the format expected by the Gemini CLI API.
@@ -101,42 +151,15 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 					if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "thinking" {
 						// Use GetThinkingText to handle wrapped thinking objects
 						thinkingText := thinking.GetThinkingText(contentResult)
-
-						// Always try cached signature first (more reliable than client-provided)
-						// Client may send stale or invalid signatures from different sessions
-						signature := ""
-						if thinkingText != "" {
-							if cachedSig := cache.GetCachedSignature(modelName, thinkingText); cachedSig != "" {
-								signature = cachedSig
-								// log.Debugf("Using cached signature for thinking block")
-							}
-						}
-
-						// Fallback to client signature only if cache miss and client signature is valid
-						if signature == "" {
-							signatureResult := contentResult.Get("signature")
-							clientSignature := ""
-							if signatureResult.Exists() && signatureResult.String() != "" {
-								arrayClientSignatures := strings.SplitN(signatureResult.String(), "#", 2)
-								if len(arrayClientSignatures) == 2 {
-									if cache.GetModelGroup(modelName) == arrayClientSignatures[0] {
-										clientSignature = arrayClientSignatures[1]
-									}
-								}
-							}
-							if cache.HasValidSignature(modelName, clientSignature) {
-								signature = clientSignature
-							}
-							// log.Debugf("Using client-provided signature for thinking block")
-						}
+						signature := resolveThinkingSignature(modelName, thinkingText, contentResult.Get("signature").String())

 						// Store for subsequent tool_use in the same message
-						if cache.HasValidSignature(modelName, signature) {
+						if hasResolvedThinkingSignature(modelName, signature) {
 							currentMessageThinkingSignature = signature
 						}

-						// Skip trailing unsigned thinking blocks on last assistant message
-						isUnsigned := !cache.HasValidSignature(modelName, signature)
+						// Skip unsigned thinking blocks instead of converting them to text.
+						isUnsigned := !hasResolvedThinkingSignature(modelName, signature)

 						// If unsigned, skip entirely (don't convert to text)
 						// Claude requires assistant messages to start with thinking blocks when thinking is enabled
@@ -198,7 +221,7 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 							// This is the approach used in opencode-google-antigravity-auth for Gemini
 							// and also works for Claude through Antigravity API
 							const skipSentinel = "skip_thought_signature_validator"
-							if cache.HasValidSignature(modelName, currentMessageThinkingSignature) {
+							if hasResolvedThinkingSignature(modelName, currentMessageThinkingSignature) {
 								partJSON, _ = sjson.SetBytes(partJSON, "thoughtSignature", currentMessageThinkingSignature)
 							} else {
 								// No valid signature - use skip sentinel to bypass validation