fix(codex): set finish_reason to "tool_calls" in non-streaming response when tool calls are present by 0oAstro · Pull Request #2444 · router-for-me/CLIProxyAPI

0oAstro · 2026-03-31T08:26:36Z

Problem

ConvertCodexResponseToOpenAINonStream unconditionally sets finish_reason = "stop" when the Codex response status is "completed", even when the response contains tool_calls. This causes any OpenAI-compatible client that inspects finish_reason to incorrectly terminate its agentic loop.

The streaming path (ConvertCodexResponseToOpenAI) already handles this correctly by checking FunctionCallIndex != -1.

Fix

Check whether toolCalls is non-empty before deciding finish_reason, mirroring the streaming path:

// Before
template, _ = sjson.SetBytes(template, "choices.0.finish_reason", "stop")
template, _ = sjson.SetBytes(template, "choices.0.native_finish_reason", "stop")

// After
finishReason := "stop"
if len(toolCalls) > 0 {
    finishReason = "tool_calls"
}
template, _ = sjson.SetBytes(template, "choices.0.finish_reason", finishReason)
template, _ = sjson.SetBytes(template, "choices.0.native_finish_reason", finishReason)

Testing

# Non-streaming with tool use — now returns "tool_calls"
curl -s '.../v1/chat/completions' \
  -d '{"model":"gpt-5.3-codex","stream":false,"tools":[...],"messages":[...]}' \
  | jq '.choices[0].finish_reason'
# "tool_calls"

# Non-streaming without tools — still returns "stop"
curl -s '.../v1/chat/completions' \
  -d '{"model":"gpt-5.3-codex","stream":false,"messages":[{"role":"user","content":"hi"}]}' \
  | jq '.choices[0].finish_reason'
# "stop"

gemini-code-assist

Code Review

This pull request updates the OpenAI response conversion logic to correctly set the finish_reason to 'tool_calls' when tool calls are present. A critical issue was identified where the 'toolCalls' variable is used outside of its scope, which will cause a compilation error. It is suggested to verify the presence of tool calls by checking the 'template' object directly using gjson.

gemini-code-assist · 2026-03-31T08:28:11Z

-			template, _ = sjson.SetBytes(template, "choices.0.finish_reason", "stop")
-			template, _ = sjson.SetBytes(template, "choices.0.native_finish_reason", "stop")
+			finishReason := "stop"
+			if len(toolCalls) > 0 {


The variable toolCalls is defined inside the if outputResult.IsArray() block (lines 288-364) and is not accessible here. This will cause a compilation error.

To fix this, you should move the declaration of toolCalls (line 292) outside of the if block. Alternatively, you can check the template for the presence of tool calls as suggested below.

Suggested change

if len(toolCalls) > 0 {

if gjson.GetBytes(template, "choices.0.message.tool_calls").IsArray() {

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chatgpt-codex-connector · 2026-03-31T08:28:41Z

-			template, _ = sjson.SetBytes(template, "choices.0.finish_reason", "stop")
-			template, _ = sjson.SetBytes(template, "choices.0.native_finish_reason", "stop")
+			finishReason := "stop"
+			if len(toolCalls) > 0 {


Move toolCalls state outside output block

toolCalls is declared inside if outputResult.IsArray() but then referenced later when setting finish_reason. In Go this identifier is out of scope at that point, so this change makes the package fail to compile (undefined toolCalls) in any build that includes this file. Please hoist the variable (or a boolean like hasToolCalls) to the outer function scope before using it in the status block.

Useful? React with 👍 / 👎.

Copilot

Pull request overview

Adjusts the Codex→OpenAI non-streaming chat-completions translator so OpenAI-compatible clients don’t prematurely exit agent loops when the Codex response includes tool calls.

Changes:

Derives choices[0].finish_reason / native_finish_reason from presence of tool calls (tool_calls vs stop) in ConvertCodexResponseToOpenAINonStream.

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Copilot · 2026-03-31T08:28:49Z

+			finishReason := "stop"
+			if len(toolCalls) > 0 {
+				finishReason = "tool_calls"
+			}
+			template, _ = sjson.SetBytes(template, "choices.0.finish_reason", finishReason)
+			template, _ = sjson.SetBytes(template, "choices.0.native_finish_reason", finishReason)


toolCalls is declared inside the if outputResult.IsArray() block earlier in this function, but it’s referenced here outside that block. In Go this will not compile (undefined: toolCalls). Move the declaration to the outer function scope (or track a separate hasToolCalls boolean) so it’s available when computing finishReason.

Copilot · 2026-03-31T08:28:50Z

+			finishReason := "stop"
+			if len(toolCalls) > 0 {
+				finishReason = "tool_calls"
+			}
+			template, _ = sjson.SetBytes(template, "choices.0.finish_reason", finishReason)
+			template, _ = sjson.SetBytes(template, "choices.0.native_finish_reason", finishReason)


This change alters non-streaming finish_reason behavior for completed responses with tool calls, but there are currently no unit tests covering ConvertCodexResponseToOpenAINonStream. Please add tests asserting choices[0].finish_reason is tool_calls when a function_call output item is present and stop when it isn’t, to prevent regressions and keep parity with the streaming path.

… when tool calls are present

xkonjin

Code Review — fix(codex): set finish_reason to "tool_calls" in non-streaming response

Overall: Good fix for a subtle OpenAI compatibility bug 🟢

The changes correctly address an issue where non-streaming Codex responses with tool calls would report finish_reason: "stop" instead of "tool_calls", which could break agent loop detection in OpenAI-compatible clients.

Positives

Scope fix: Moving var toolCalls declaration outside the outputResult.IsArray() block ensures the variable is accessible when determining the finish reason. This is the correct fix.
Clean finish_reason logic: The conditional check if len(toolCalls) > 0 properly differentiates between content-only responses and tool call responses.

Minor Concerns

1. Test coverage (important)
This PR lacks any test coverage for the fix. Consider adding:

A test case where the Codex response contains tool calls and verifying finish_reason equals "tool_calls"
A test case with mixed content + tool calls
A regression test to prevent this from breaking in the future

2. Edge case consideration
What happens if outputResult is not an array but the Codex response still contains tool calls via another path? The current logic would result in finish_reason: "stop". Is this the correct fallback behavior? A comment explaining this assumption would help future maintainers.

Verdict

LGTM as a correctness fix, but recommend adding test coverage before merging to prevent regression.

luispater

Summary

This fixes ConvertCodexResponseToOpenAINonStream always setting choices[0].finish_reason to "stop" for status=="completed", even when the response includes tool calls. The change mirrors the streaming path behavior and prevents OpenAI-compatible clients from incorrectly terminating tool/agent loops.

Key findings

Correctly sets finish_reason (and native_finish_reason) to "tool_calls" when toolCalls is non-empty; otherwise keeps "stop".
Scope change for toolCalls is minimal and only enables the finish-reason decision after output parsing.

Tests

CI build is green.
Suggest adding a focused unit test for the non-streaming tool-call finish reason to prevent regressions.

This is an automated Codex review result and still requires manual verification by a human reviewer.

Copilot AI review requested due to automatic review settings March 31, 2026 08:26

Copilot started reviewing on behalf of 0oAstro March 31, 2026 08:27 View session

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Copilot AI reviewed Mar 31, 2026

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fix(codex): set finish_reason to tool_calls in non-streaming response…

ec77f4a

… when tool calls are present

0oAstro force-pushed the fix/codex-nonstream-finish-reason-tool-calls branch from 532c3aa to ec77f4a Compare March 31, 2026 08:42

xkonjin reviewed Mar 31, 2026

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luispater approved these changes Apr 1, 2026

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luispater added the codex label Apr 1, 2026

luispater changed the base branch from main to dev April 2, 2026 02:01

luispater approved these changes Apr 2, 2026

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luispater merged commit b05f575 into router-for-me:dev Apr 2, 2026
1 of 2 checks passed

0oAstro deleted the fix/codex-nonstream-finish-reason-tool-calls branch April 3, 2026 13:26

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fix(codex): set finish_reason to "tool_calls" in non-streaming response when tool calls are present#2444

fix(codex): set finish_reason to "tool_calls" in non-streaming response when tool calls are present#2444
luispater merged 1 commit intorouter-for-me:devfrom
0oAstro:fix/codex-nonstream-finish-reason-tool-calls

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	if len(toolCalls) > 0 {
	if gjson.GetBytes(template, "choices.0.message.tool_calls").IsArray() {

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0oAstro commented Mar 31, 2026

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Code Review — fix(codex): set finish_reason to "tool_calls" in non-streaming response

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