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fix(mimic): rewrite tool_use names in messages to match renamed tools

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The Claude Code mimic path rewrites tool names in tools[] (and
tool_choice) but left tool_use blocks in messages[] with their
original names. Anthropic validates that every tool referenced by
a tool_use block is declared in tools[], so the mismatch produces:

    messages.N.content.M: Input tag 'original_name' not found in tools

(surfaced as HTTP 400 directly, or wrapped as 424 by upstream proxies
such as Bedrock gateways.)

The previous code comment asserted 'this matches Parrot; response-side
bytes.Replace will restore the names'. Parrot's behavior is fine for
Claude Code's own tool set, but breaks once the upstream client sends
additional tools (e.g. web_search) that are not part of Claude Code
and therefore get renamed here.

Fix: apply the same ToolNameRewrite to messages[].content[] blocks
where type == 'tool_use', keeping tools[], tool_choice and messages
self-consistent before the request reaches Anthropic. tool_result
blocks reference tools via tool_use_id, not name, so no change is
needed there.

A new unit test covers the full rewrite flow and guards against
server tools (type != '') being affected.
This commit is contained in:
iFwu
2026-05-10 18:01:19 +08:00
parent dbc8ae658c
commit f97b853460
2 changed files with 62 additions and 6 deletions
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backend/internal/service/gateway_tool_rewrite_test.go
+24
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@@ -84,6 +84,30 @@ func TestApplyToolNameRewriteToBody_RenamesToolsAndToolChoice(t *testing.T) {
require.Equal(t, "tool", gjson.GetBytes(out, "tool_choice.type").String())
}
func TestApplyToolNameRewriteToBody_RenamesToolUseInMessages(t *testing.T) {
// sessions_list -> cc_sess_list (static prefix: sessions_ -> sessions_)
// web_search is a server tool (type != ""), not rewritten
// messages tool_use names must be rewritten to match tools[]
body := []byte(`{"tools":[{"name":"sessions_list","input_schema":{}},{"name":"web_search","type":"web_search_20250305"}],"messages":[{"role":"user","content":[{"type":"text","text":"hi"}]},{"role":"assistant","content":[{"type":"tool_use","id":"tu_01","name":"sessions_list","input":{}},{"type":"text","text":"thinking"}]},{"role":"user","content":[{"type":"tool_result","tool_use_id":"tu_01","content":"ok"}]}]}`)
rw := buildToolNameRewriteFromBody(body)
require.NotNil(t, rw)
require.Equal(t, "cc_sess_list", rw.Forward["sessions_list"])
out := applyToolNameRewriteToBody(body, rw)
// tools[0].name rewritten
require.Equal(t, "cc_sess_list", gjson.GetBytes(out, "tools.0.name").String())
// tools[1].name untouched (server tool)
require.Equal(t, "web_search", gjson.GetBytes(out, "tools.1.name").String())
// messages[1].content[0].name (tool_use) also rewritten to match tools
require.Equal(t, "cc_sess_list", gjson.GetBytes(out, "messages.1.content.0.name").String())
// messages[1].content[1] (text) untouched
require.Equal(t, "thinking", gjson.GetBytes(out, "messages.1.content.1.text").String())
// messages[2].content[0] (tool_result) untouched — no name field in tool_result
require.Equal(t, "ok", gjson.GetBytes(out, "messages.2.content.0.content").String())
}
func TestApplyToolsLastCacheBreakpoint_InjectsDefault(t *testing.T) {
body := []byte(`{"tools":[{"name":"a","input_schema":{}},{"name":"b","input_schema":{}}]}`)
out := applyToolsLastCacheBreakpoint(body)