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fix(claude): add dynamic snakeCaseToTitleCase fallback for OAuth tool rename #2839

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fix(claude): add dynamic snakeCaseToTitleCase fallback for OAuth tool rename #2839

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145 changes: 125 additions & 20 deletions internal/runtime/executor/claude_executor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ import (
"net/textproto"
"strings"
"time"
"unicode"

"github.com/andybalholm/brotli"
"github.com/google/uuid"
Expand Down Expand Up @@ -79,6 +80,56 @@ var oauthToolRenameReverseMap = func() map[string]string {
// even after remapping. Currently empty — all tools are mapped instead of removed.
var oauthToolsToRemove = map[string]bool{}

// snakeCaseToTitleCase converts snake_case or kebab-case tool names to TitleCase.
// MCP tools (containing "__") are left unchanged as they follow a separate naming convention.
// Examples: "sessions_list" -> "SessionsList", "agents_list" -> "AgentsList"
func snakeCaseToTitleCase(name string) string {
if name == "" {
return name
}
// Skip MCP tools (mcp__server__tool format)
if strings.Contains(name, "__") {
return name
}
// Skip if no separators (already TitleCase or single word)
if !strings.ContainsAny(name, "_-") {
return name
}
var sb strings.Builder
capitalize := true
for _, r := range name {
if r == '_' || r == '-' {
capitalize = true
continue
}
if capitalize {
sb.WriteRune(unicode.ToUpper(r))
capitalize = false
} else {
sb.WriteRune(r)
}
}
return sb.String()
}

// dynamicOAuthToolRename attempts to rename a tool name using snakeCaseToTitleCase
// when it is not found in the static oauthToolRenameMap. Returns the new name and
// true if a rename was performed, or the original name and false otherwise.
// Collision check ensures no clash with existing static map values.
func dynamicOAuthToolRename(name string) (string, bool) {
newName := snakeCaseToTitleCase(name)
if newName == name {
return name, false
}
// Collision check against existing static mappings
for _, v := range oauthToolRenameMap {
if v == newName {
return name, false
}
}
return newName, true
}

// Anthropic-compatible upstreams may reject or even crash when Claude models
// omit max_tokens. Prefer registered model metadata before using a fallback.
const defaultModelMaxTokens = 1024
Expand Down Expand Up @@ -193,14 +244,15 @@ func (e *ClaudeExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, r
bodyForUpstream := body
oauthToken := isClaudeOAuthToken(apiKey)
oauthToolNamesRemapped := false
var oauthDynReverse map[string]string
if oauthToken && !auth.ToolPrefixDisabled() {
bodyForUpstream = applyClaudeToolPrefix(body, claudeToolPrefix)
}
// Remap third-party tool names to Claude Code equivalents and remove
// tools without official counterparts. This prevents Anthropic from
// fingerprinting the request as third-party via tool naming patterns.
if oauthToken {
bodyForUpstream, oauthToolNamesRemapped = remapOAuthToolNames(bodyForUpstream)
bodyForUpstream, oauthToolNamesRemapped, oauthDynReverse = remapOAuthToolNames(bodyForUpstream)
}
// Enable cch signing by default for OAuth tokens (not just experimental flag).
// Claude Code always computes cch; missing or invalid cch is a detectable fingerprint.
Expand Down Expand Up @@ -298,8 +350,17 @@ func (e *ClaudeExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, r
data = stripClaudeToolPrefixFromResponse(data, claudeToolPrefix)
}
// Reverse the OAuth tool name remap so the downstream client sees original names.
// When stream=true (format translation), data is SSE-formatted; apply line-by-line reverse.
if isClaudeOAuthToken(apiKey) && oauthToolNamesRemapped {
data = reverseRemapOAuthToolNames(data)
if stream {
var reversedLines [][]byte
for _, line := range bytes.Split(data, []byte("\n")) {
reversedLines = append(reversedLines, reverseRemapOAuthToolNamesFromStreamLine(line, oauthDynReverse))
}
data = bytes.Join(reversedLines, []byte("\n"))
} else {
data = reverseRemapOAuthToolNames(data, oauthDynReverse)
}
}
var param any
out := sdktranslator.TranslateNonStream(
Expand Down Expand Up @@ -375,14 +436,15 @@ func (e *ClaudeExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
bodyForUpstream := body
oauthToken := isClaudeOAuthToken(apiKey)
oauthToolNamesRemapped := false
var oauthDynReverse map[string]string
if oauthToken && !auth.ToolPrefixDisabled() {
bodyForUpstream = applyClaudeToolPrefix(body, claudeToolPrefix)
}
// Remap third-party tool names to Claude Code equivalents and remove
// tools without official counterparts. This prevents Anthropic from
// fingerprinting the request as third-party via tool naming patterns.
if oauthToken {
bodyForUpstream, oauthToolNamesRemapped = remapOAuthToolNames(bodyForUpstream)
bodyForUpstream, oauthToolNamesRemapped, oauthDynReverse = remapOAuthToolNames(bodyForUpstream)
}
// Enable cch signing by default for OAuth tokens (not just experimental flag).
if oauthToken || experimentalCCHSigningEnabled(e.cfg, auth) {
Expand Down Expand Up @@ -477,7 +539,7 @@ func (e *ClaudeExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
line = stripClaudeToolPrefixFromStreamLine(line, claudeToolPrefix)
}
if isClaudeOAuthToken(apiKey) && oauthToolNamesRemapped {
line = reverseRemapOAuthToolNamesFromStreamLine(line)
line = reverseRemapOAuthToolNamesFromStreamLine(line, oauthDynReverse)
}
// Forward the line as-is to preserve SSE format
cloned := make([]byte, len(line)+1)
Expand Down Expand Up @@ -507,7 +569,7 @@ func (e *ClaudeExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
line = stripClaudeToolPrefixFromStreamLine(line, claudeToolPrefix)
}
if isClaudeOAuthToken(apiKey) && oauthToolNamesRemapped {
line = reverseRemapOAuthToolNamesFromStreamLine(line)
line = reverseRemapOAuthToolNamesFromStreamLine(line, oauthDynReverse)
}
chunks := sdktranslator.TranslateStream(
ctx,
Expand Down Expand Up @@ -563,7 +625,7 @@ func (e *ClaudeExecutor) CountTokens(ctx context.Context, auth *cliproxyauth.Aut
}
// Remap tool names for OAuth token requests to avoid third-party fingerprinting.
if isClaudeOAuthToken(apiKey) {
body, _ = remapOAuthToolNames(body)
body, _, _ = remapOAuthToolNames(body)
}

url := fmt.Sprintf("%s/v1/messages/count_tokens?beta=true", baseURL)
Expand Down Expand Up @@ -1020,8 +1082,25 @@ func isClaudeOAuthToken(apiKey string) bool {
// It operates on: tools[].name, tool_choice.name, and all tool_use/tool_reference
// references in messages. Removed tools' corresponding tool_result blocks are preserved
// (they just become orphaned, which is safe for Claude).
func remapOAuthToolNames(body []byte) ([]byte, bool) {
func remapOAuthToolNames(body []byte) ([]byte, bool, map[string]string) {
renamed := false
dynReverse := map[string]string{}

// resolveNewName tries the static map first, then falls back to dynamic
// snakeCaseToTitleCase conversion. Dynamic renames are recorded in dynReverse
// for later response decoding.
resolveNewName := func(name string) (string, bool) {
if newName, ok := oauthToolRenameMap[name]; ok && newName != name {
return newName, true
}
if newName, ok := dynamicOAuthToolRename(name); ok {
dynReverse[newName] = name
log.Debugf("claude: dynamic tool rename: %q -> %q", name, newName)
return newName, true
}
return name, false
}

// 1. Rewrite tools array in a single pass (if present).
// IMPORTANT: do not mutate names first and then rebuild from an older gjson
// snapshot. gjson results are snapshots of the original bytes; rebuilding from a
Expand Down Expand Up @@ -1050,7 +1129,7 @@ func remapOAuthToolNames(body []byte) ([]byte, bool) {
}

toolJSON := tool.Raw
if newName, ok := oauthToolRenameMap[name]; ok && newName != name {
if newName, ok := resolveNewName(name); ok {
updatedTool, err := sjson.Set(toolJSON, "name", newName)
if err == nil {
toolJSON = updatedTool
Expand All @@ -1077,7 +1156,7 @@ func remapOAuthToolNames(body []byte) ([]byte, bool) {
// The chosen tool was removed from the tools array, so drop tool_choice to
// keep the payload internally consistent and fall back to normal auto tool use.
body, _ = sjson.DeleteBytes(body, "tool_choice")
} else if newName, ok := oauthToolRenameMap[tcName]; ok && newName != tcName {
} else if newName, ok := resolveNewName(tcName); ok {
body, _ = sjson.SetBytes(body, "tool_choice.name", newName)
renamed = true
}
Expand All @@ -1096,14 +1175,14 @@ func remapOAuthToolNames(body []byte) ([]byte, bool) {
switch partType {
case "tool_use":
name := part.Get("name").String()
if newName, ok := oauthToolRenameMap[name]; ok && newName != name {
if newName, ok := resolveNewName(name); ok {
path := fmt.Sprintf("messages.%d.content.%d.name", msgIndex.Int(), contentIndex.Int())
body, _ = sjson.SetBytes(body, path, newName)
renamed = true
}
case "tool_reference":
toolName := part.Get("tool_name").String()
if newName, ok := oauthToolRenameMap[toolName]; ok && newName != toolName {
if newName, ok := resolveNewName(toolName); ok {
path := fmt.Sprintf("messages.%d.content.%d.tool_name", msgIndex.Int(), contentIndex.Int())
body, _ = sjson.SetBytes(body, path, newName)
renamed = true
Expand All @@ -1117,7 +1196,7 @@ func remapOAuthToolNames(body []byte) ([]byte, bool) {
nestedContent.ForEach(func(nestedIndex, nestedPart gjson.Result) bool {
if nestedPart.Get("type").String() == "tool_reference" {
nestedToolName := nestedPart.Get("tool_name").String()
if newName, ok := oauthToolRenameMap[nestedToolName]; ok && newName != nestedToolName {
if newName, ok := resolveNewName(nestedToolName); ok {
nestedPath := fmt.Sprintf("messages.%d.content.%d.content.%d.tool_name", msgIndex.Int(), contentIndex.Int(), nestedIndex.Int())
body, _ = sjson.SetBytes(body, nestedPath, newName)
renamed = true
Expand All @@ -1133,13 +1212,26 @@ func remapOAuthToolNames(body []byte) ([]byte, bool) {
})
}

return body, renamed
return body, renamed, dynReverse
}

// reverseRemapOAuthToolNames reverses the tool name mapping for non-stream responses.
// It maps Claude Code TitleCase names back to the original lowercase names so the
// downstream client receives tool names it recognizes.
func reverseRemapOAuthToolNames(body []byte) []byte {
// downstream client receives tool names it recognizes. dynReverse contains per-request
// mappings for dynamically renamed tools (from snakeCaseToTitleCase fallback).
func reverseRemapOAuthToolNames(body []byte, dynReverse map[string]string) []byte {
resolveOrigName := func(name string) (string, bool) {
if origName, ok := oauthToolRenameReverseMap[name]; ok {
return origName, true
}
if dynReverse != nil {
if origName, ok := dynReverse[name]; ok {
return origName, true
}
}
return name, false
}

content := gjson.GetBytes(body, "content")
if !content.Exists() || !content.IsArray() {
return body
Expand All @@ -1149,13 +1241,13 @@ func reverseRemapOAuthToolNames(body []byte) []byte {
switch partType {
case "tool_use":
name := part.Get("name").String()
if origName, ok := oauthToolRenameReverseMap[name]; ok {
if origName, ok := resolveOrigName(name); ok {
path := fmt.Sprintf("content.%d.name", index.Int())
body, _ = sjson.SetBytes(body, path, origName)
}
case "tool_reference":
toolName := part.Get("tool_name").String()
if origName, ok := oauthToolRenameReverseMap[toolName]; ok {
if origName, ok := resolveOrigName(toolName); ok {
path := fmt.Sprintf("content.%d.tool_name", index.Int())
body, _ = sjson.SetBytes(body, path, origName)
}
Expand All @@ -1166,7 +1258,20 @@ func reverseRemapOAuthToolNames(body []byte) []byte {
}

// reverseRemapOAuthToolNamesFromStreamLine reverses the tool name mapping for SSE stream lines.
func reverseRemapOAuthToolNamesFromStreamLine(line []byte) []byte {
// dynReverse contains per-request mappings for dynamically renamed tools.
func reverseRemapOAuthToolNamesFromStreamLine(line []byte, dynReverse map[string]string) []byte {
resolveOrigName := func(name string) (string, bool) {
if origName, ok := oauthToolRenameReverseMap[name]; ok {
return origName, true
}
if dynReverse != nil {
if origName, ok := dynReverse[name]; ok {
return origName, true
}
}
return name, false
}

payload := helps.JSONPayload(line)
if len(payload) == 0 || !gjson.ValidBytes(payload) {
return line
Expand All @@ -1184,7 +1289,7 @@ func reverseRemapOAuthToolNamesFromStreamLine(line []byte) []byte {
switch blockType {
case "tool_use":
name := contentBlock.Get("name").String()
if origName, ok := oauthToolRenameReverseMap[name]; ok {
if origName, ok := resolveOrigName(name); ok {
updated, err = sjson.SetBytes(payload, "content_block.name", origName)
if err != nil {
return line
Expand All @@ -1194,7 +1299,7 @@ func reverseRemapOAuthToolNamesFromStreamLine(line []byte) []byte {
}
case "tool_reference":
toolName := contentBlock.Get("tool_name").String()
if origName, ok := oauthToolRenameReverseMap[toolName]; ok {
if origName, ok := resolveOrigName(toolName); ok {
updated, err = sjson.SetBytes(payload, "content_block.tool_name", origName)
if err != nil {
return line
Expand Down
8 changes: 4 additions & 4 deletions internal/runtime/executor/claude_executor_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1953,7 +1953,7 @@ func TestNormalizeClaudeTemperatureForThinking_AfterForcedToolChoiceKeepsOrigina
func TestRemapOAuthToolNames_TitleCase_NoReverseNeeded(t *testing.T) {
body := []byte(`{"tools":[{"name":"Bash","description":"Run shell commands","input_schema":{"type":"object","properties":{"cmd":{"type":"string"}}}}],"messages":[{"role":"user","content":[{"type":"text","text":"hi"}]}]}`)

out, renamed := remapOAuthToolNames(body)
out, renamed, dynReverse := remapOAuthToolNames(body)
if renamed {
t.Fatalf("renamed = true, want false")
}
Expand All @@ -1964,7 +1964,7 @@ func TestRemapOAuthToolNames_TitleCase_NoReverseNeeded(t *testing.T) {
resp := []byte(`{"content":[{"type":"tool_use","id":"toolu_01","name":"Bash","input":{"cmd":"ls"}}]}`)
reversed := resp
if renamed {
reversed = reverseRemapOAuthToolNames(resp)
reversed = reverseRemapOAuthToolNames(resp, dynReverse)
}
if got := gjson.GetBytes(reversed, "content.0.name").String(); got != "Bash" {
t.Fatalf("content.0.name = %q, want %q", got, "Bash")
Expand All @@ -1974,7 +1974,7 @@ func TestRemapOAuthToolNames_TitleCase_NoReverseNeeded(t *testing.T) {
func TestRemapOAuthToolNames_Lowercase_ReverseApplied(t *testing.T) {
body := []byte(`{"tools":[{"name":"bash","description":"Run shell commands","input_schema":{"type":"object","properties":{"cmd":{"type":"string"}}}}],"messages":[{"role":"user","content":[{"type":"text","text":"hi"}]}]}`)

out, renamed := remapOAuthToolNames(body)
out, renamed, dynReverse := remapOAuthToolNames(body)
if !renamed {
t.Fatalf("renamed = false, want true")
}
Expand All @@ -1985,7 +1985,7 @@ func TestRemapOAuthToolNames_Lowercase_ReverseApplied(t *testing.T) {
resp := []byte(`{"content":[{"type":"tool_use","id":"toolu_01","name":"Bash","input":{"cmd":"ls"}}]}`)
reversed := resp
if renamed {
reversed = reverseRemapOAuthToolNames(resp)
reversed = reverseRemapOAuthToolNames(resp, dynReverse)
}
if got := gjson.GetBytes(reversed, "content.0.name").String(); got != "bash" {
t.Fatalf("content.0.name = %q, want %q", got, "bash")
Expand Down
6 changes: 3 additions & 3 deletions internal/runtime/executor/helps/claude_device_profile.go
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Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,8 @@ import (
)

const (
defaultClaudeFingerprintUserAgent = "claude-cli/2.1.63 (external, cli)"
defaultClaudeFingerprintPackageVersion = "0.74.0"
defaultClaudeFingerprintUserAgent = "claude-cli/2.1.108 (external, sdk-cli)"
defaultClaudeFingerprintPackageVersion = "0.81.0"
defaultClaudeFingerprintRuntimeVersion = "v24.3.0"
defaultClaudeFingerprintOS = "MacOS"
defaultClaudeFingerprintArch = "arm64"
Expand Down Expand Up @@ -365,7 +365,7 @@ func DefaultClaudeVersion(cfg *config.Config) string {
if version, ok := parseClaudeCLIVersion(profile.UserAgent); ok {
return strconv.Itoa(version.major) + "." + strconv.Itoa(version.minor) + "." + strconv.Itoa(version.patch)
}
return "2.1.63"
return "2.1.108"
}

func ApplyClaudeLegacyDeviceHeaders(r *http.Request, ginHeaders http.Header, cfg *config.Config) {
Expand Down
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