diff --git a/internal/translator/antigravity/claude/antigravity_claude_response.go b/internal/translator/antigravity/claude/antigravity_claude_response.go
index 875e54a71..532f2be42 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_response.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_response.go
@@ -350,14 +350,12 @@ func resolveStopReason(params *Params) string {
 		return "tool_use"
 	}
 
-	switch params.FinishReason {
-	case "MAX_TOKENS":
+	if params.FinishReason == "MAX_TOKENS" {
 		return "max_tokens"
-	case "STOP", "FINISH_REASON_UNSPECIFIED", "UNKNOWN":
-		return "end_turn"
 	}
 
 	return "end_turn"
+
 }
 
 // ConvertAntigravityResponseToClaudeNonStream converts a non-streaming Gemini CLI response to a non-streaming Claude response.
@@ -498,13 +496,8 @@ func ConvertAntigravityResponseToClaudeNonStream(_ context.Context, _ string, or
 		stopReason = "tool_use"
 	} else {
 		if finish := root.Get("response.candidates.0.finishReason"); finish.Exists() {
-			switch finish.String() {
-			case "MAX_TOKENS":
+			if finish.String() == "MAX_TOKENS" {
 				stopReason = "max_tokens"
-			case "STOP", "FINISH_REASON_UNSPECIFIED", "UNKNOWN":
-				stopReason = "end_turn"
-			default:
-				stopReason = "end_turn"
 			}
 		}
 	}
diff --git a/internal/translator/antigravity/openai/chat-completions/antigravity_openai_response.go b/internal/translator/antigravity/openai/chat-completions/antigravity_openai_response.go
index 1b7866d01..143ebefd2 100644
--- a/internal/translator/antigravity/openai/chat-completions/antigravity_openai_response.go
+++ b/internal/translator/antigravity/openai/chat-completions/antigravity_openai_response.go
@@ -79,11 +79,17 @@ func ConvertAntigravityResponseToOpenAI(_ context.Context, _ string, originalReq
 		template, _ = sjson.Set(template, "id", responseIDResult.String())
 	}
 
-	// Extract and set the finish reason.
-	if finishReasonResult := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason"); finishReasonResult.Exists() {
-		template, _ = sjson.Set(template, "choices.0.finish_reason", strings.ToLower(finishReasonResult.String()))
-		template, _ = sjson.Set(template, "choices.0.native_finish_reason", strings.ToLower(finishReasonResult.String()))
+	// Extract the finish reason (set after payload processing).
+	finishReason := ""
+	if stopReasonResult := gjson.GetBytes(rawJSON, "response.stop_reason"); stopReasonResult.Exists() {
+		finishReason = stopReasonResult.String()
 	}
+	if finishReason == "" {
+		if finishReasonResult := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason"); finishReasonResult.Exists() {
+			finishReason = finishReasonResult.String()
+		}
+	}
+	finishReason = strings.ToLower(finishReason)
 
 	// Extract and set usage metadata (token counts).
 	if usageResult := gjson.GetBytes(rawJSON, "response.usageMetadata"); usageResult.Exists() {
@@ -198,6 +204,12 @@ func ConvertAntigravityResponseToOpenAI(_ context.Context, _ string, originalReq
 	if hasFunctionCall {
 		template, _ = sjson.Set(template, "choices.0.finish_reason", "tool_calls")
 		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
+	} else if finishReason != "" && (*param).(*convertCliResponseToOpenAIChatParams).FunctionIndex == 0 {
+		// Only pass through specific finish reasons
+		if finishReason == "max_tokens" || finishReason == "stop" {
+			template, _ = sjson.Set(template, "choices.0.finish_reason", finishReason)
+			template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReason)
+		}
 	}
 
 	return []string{template}
diff --git a/internal/translator/codex/claude/codex_claude_response.go b/internal/translator/codex/claude/codex_claude_response.go
index e3909d45e..e02da1a5a 100644
--- a/internal/translator/codex/claude/codex_claude_response.go
+++ b/internal/translator/codex/claude/codex_claude_response.go
@@ -99,12 +99,16 @@ func ConvertCodexResponseToClaude(_ context.Context, _ string, originalRequestRa
 		output = "event: content_block_stop\n"
 		output += fmt.Sprintf("data: %s\n\n", template)
 	} else if typeStr == "response.completed" {
-		template = `{"type":"message_delta","delta":{"stop_reason":"tool_use","stop_sequence":null},"usage":{"input_tokens":0,"output_tokens":0}}`
+		template = `{"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"input_tokens":0,"output_tokens":0}}`
 		p := (*param).(*bool)
 		if *p {
 			template, _ = sjson.Set(template, "delta.stop_reason", "tool_use")
 		} else {
-			template, _ = sjson.Set(template, "delta.stop_reason", "end_turn")
+			stopReason := rootResult.Get("response.stop_reason").String()
+			// Only pass through specific stop reasons
+			if stopReason == "max_tokens" || stopReason == "stop" || stopReason == "end_turn" {
+				template, _ = sjson.Set(template, "delta.stop_reason", stopReason)
+			}
 		}
 		template, _ = sjson.Set(template, "usage.input_tokens", rootResult.Get("response.usage.input_tokens").Int())
 		template, _ = sjson.Set(template, "usage.output_tokens", rootResult.Get("response.usage.output_tokens").Int())
diff --git a/internal/translator/gemini-cli/claude/gemini-cli_claude_response.go b/internal/translator/gemini-cli/claude/gemini-cli_claude_response.go
index 2f8e95488..f9d5b016f 100644
--- a/internal/translator/gemini-cli/claude/gemini-cli_claude_response.go
+++ b/internal/translator/gemini-cli/claude/gemini-cli_claude_response.go
@@ -244,6 +244,12 @@ func ConvertGeminiCLIResponseToClaude(_ context.Context, _ string, originalReque
 				// Set tool_use stop reason if tools were used in this response
 				if usedTool {
 					template = `{"type":"message_delta","delta":{"stop_reason":"tool_use","stop_sequence":null},"usage":{"input_tokens":0,"output_tokens":0}}`
+				} else {
+					if finish := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason"); finish.Exists() {
+						if finish.String() == "MAX_TOKENS" {
+							template, _ = sjson.Set(template, "delta.stop_reason", "max_tokens")
+						}
+					}
 				}
 
 				// Include thinking tokens in output token count if present
@@ -352,13 +358,8 @@ func ConvertGeminiCLIResponseToClaudeNonStream(_ context.Context, _ string, orig
 		stopReason = "tool_use"
 	} else {
 		if finish := root.Get("response.candidates.0.finishReason"); finish.Exists() {
-			switch finish.String() {
-			case "MAX_TOKENS":
+			if finish.String() == "MAX_TOKENS" {
 				stopReason = "max_tokens"
-			case "STOP", "FINISH_REASON_UNSPECIFIED", "UNKNOWN":
-				stopReason = "end_turn"
-			default:
-				stopReason = "end_turn"
 			}
 		}
 	}
diff --git a/internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go b/internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go
index 5a1faf510..e94d8ea7a 100644
--- a/internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go
+++ b/internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go
@@ -77,11 +77,17 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 		template, _ = sjson.Set(template, "id", responseIDResult.String())
 	}
 
-	// Extract and set the finish reason.
-	if finishReasonResult := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason"); finishReasonResult.Exists() {
-		template, _ = sjson.Set(template, "choices.0.finish_reason", strings.ToLower(finishReasonResult.String()))
-		template, _ = sjson.Set(template, "choices.0.native_finish_reason", strings.ToLower(finishReasonResult.String()))
+	// Extract the finish reason (set after payload processing).
+	finishReason := ""
+	if stopReasonResult := gjson.GetBytes(rawJSON, "response.stop_reason"); stopReasonResult.Exists() {
+		finishReason = stopReasonResult.String()
 	}
+	if finishReason == "" {
+		if finishReasonResult := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason"); finishReasonResult.Exists() {
+			finishReason = finishReasonResult.String()
+		}
+	}
+	finishReason = strings.ToLower(finishReason)
 
 	// Extract and set usage metadata (token counts).
 	if usageResult := gjson.GetBytes(rawJSON, "response.usageMetadata"); usageResult.Exists() {
@@ -187,6 +193,12 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 	if hasFunctionCall {
 		template, _ = sjson.Set(template, "choices.0.finish_reason", "tool_calls")
 		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
+	} else if finishReason != "" && (*param).(*convertCliResponseToOpenAIChatParams).FunctionIndex == 0 {
+		// Only pass through specific finish reasons
+		if finishReason == "max_tokens" || finishReason == "stop" {
+			template, _ = sjson.Set(template, "choices.0.finish_reason", finishReason)
+			template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReason)
+		}
 	}
 
 	return []string{template}
diff --git a/internal/translator/gemini/claude/gemini_claude_response.go b/internal/translator/gemini/claude/gemini_claude_response.go
index db14c78a1..d245ca9f4 100644
--- a/internal/translator/gemini/claude/gemini_claude_response.go
+++ b/internal/translator/gemini/claude/gemini_claude_response.go
@@ -251,6 +251,12 @@ func ConvertGeminiResponseToClaude(_ context.Context, _ string, originalRequestR
 				template := `{"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"input_tokens":0,"output_tokens":0}}`
 				if usedTool {
 					template = `{"type":"message_delta","delta":{"stop_reason":"tool_use","stop_sequence":null},"usage":{"input_tokens":0,"output_tokens":0}}`
+				} else {
+					if finish := gjson.GetBytes(rawJSON, "candidates.0.finishReason"); finish.Exists() {
+						if finish.String() == "MAX_TOKENS" {
+							template, _ = sjson.Set(template, "delta.stop_reason", "max_tokens")
+						}
+					}
 				}
 
 				thoughtsTokenCount := usageResult.Get("thoughtsTokenCount").Int()
@@ -358,13 +364,8 @@ func ConvertGeminiResponseToClaudeNonStream(_ context.Context, _ string, origina
 		stopReason = "tool_use"
 	} else {
 		if finish := root.Get("candidates.0.finishReason"); finish.Exists() {
-			switch finish.String() {
-			case "MAX_TOKENS":
+			if finish.String() == "MAX_TOKENS" {
 				stopReason = "max_tokens"
-			case "STOP", "FINISH_REASON_UNSPECIFIED", "UNKNOWN":
-				stopReason = "end_turn"
-			default:
-				stopReason = "end_turn"
 			}
 		}
 	}
diff --git a/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go b/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go
index 52fbba430..0efdead69 100644
--- a/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go
+++ b/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go
@@ -81,11 +81,17 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 		template, _ = sjson.Set(template, "id", responseIDResult.String())
 	}
 
-	// Extract and set the finish reason.
-	if finishReasonResult := gjson.GetBytes(rawJSON, "candidates.0.finishReason"); finishReasonResult.Exists() {
-		template, _ = sjson.Set(template, "choices.0.finish_reason", strings.ToLower(finishReasonResult.String()))
-		template, _ = sjson.Set(template, "choices.0.native_finish_reason", strings.ToLower(finishReasonResult.String()))
+	// Extract the finish reason (set after payload processing).
+	finishReason := ""
+	if stopReasonResult := gjson.GetBytes(rawJSON, "stop_reason"); stopReasonResult.Exists() {
+		finishReason = stopReasonResult.String()
 	}
+	if finishReason == "" {
+		if finishReasonResult := gjson.GetBytes(rawJSON, "candidates.0.finishReason"); finishReasonResult.Exists() {
+			finishReason = finishReasonResult.String()
+		}
+	}
+	finishReason = strings.ToLower(finishReason)
 
 	// Extract and set usage metadata (token counts).
 	if usageResult := gjson.GetBytes(rawJSON, "usageMetadata"); usageResult.Exists() {
@@ -199,6 +205,12 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 	if hasFunctionCall {
 		template, _ = sjson.Set(template, "choices.0.finish_reason", "tool_calls")
 		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
+	} else if finishReason != "" && (*param).(*convertGeminiResponseToOpenAIChatParams).FunctionIndex == 0 {
+		// Only pass through specific finish reasons
+		if finishReason == "max_tokens" || finishReason == "stop" {
+			template, _ = sjson.Set(template, "choices.0.finish_reason", finishReason)
+			template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReason)
+		}
 	}
 
 	return []string{template}