fix: translation failures for OpenAI-format providers in Claude CLI (#632)

- Handle reasoning_details[] array (StepFun/OpenRouter format) in sanitizer and translator
- Handle 'reasoning' field alias → reasoning_content in streaming and non-streaming paths
- Cross-map input_tokens/output_tokens ↔ prompt_tokens/completion_tokens in filterUsageForFormat
- Fix extractUsage to accept input_tokens/output_tokens as alternative field names
- All 936 tests pass

open-sse/handlers/responseSanitizer.ts

@@ -172,6 +172,44 @@ function sanitizeMessage(msg: unknown): unknown {
     sanitized.reasoning_content = msgRecord.reasoning_content;
   }
 
+  // Handle 'reasoning' field alias (some providers use this instead of reasoning_content)
+  if (
+    msgRecord.reasoning &&
+    typeof msgRecord.reasoning === "string" &&
+    !sanitized.reasoning_content
+  ) {
+    sanitized.reasoning_content = msgRecord.reasoning;
+  }
+
+  // Handle reasoning_details[] array (StepFun/OpenRouter format)
+  // Structure: [{ type: "reasoning.text", text: "...", format: "unknown", index: 0 }]
+  if (Array.isArray(msgRecord.reasoning_details) && !sanitized.reasoning_content) {
+    const reasoningParts: string[] = [];
+    for (const detail of msgRecord.reasoning_details) {
+      const detailObj = detail && typeof detail === "object" ? (detail as JsonRecord) : null;
+      if (!detailObj) continue;
+      const detailType = typeof detailObj.type === "string" ? detailObj.type : "";
+      const detailText =
+        typeof detailObj.text === "string"
+          ? detailObj.text
+          : typeof detailObj.content === "string"
+            ? detailObj.content
+            : "";
+      if (
+        detailText &&
+        (detailType === "reasoning" ||
+          detailType === "reasoning.text" ||
+          detailType === "thinking" ||
+          detailType === "")
+      ) {
+        reasoningParts.push(detailText);
+      }
+    }
+    if (reasoningParts.length > 0) {
+      sanitized.reasoning_content = reasoningParts.join("");
+    }
+  }
+
   // Preserve tool_calls
   if (msgRecord.tool_calls) {
     sanitized.tool_calls = msgRecord.tool_calls;
@@ -258,6 +296,26 @@ export function sanitizeStreamingChunk(parsed: unknown): unknown {
           if (deltaRecord.content !== undefined) delta.content = deltaRecord.content;
           if (deltaRecord.reasoning_content !== undefined) {
             delta.reasoning_content = deltaRecord.reasoning_content;
+          } else if (typeof deltaRecord.reasoning === "string" && deltaRecord.reasoning) {
+            // Alias: some providers use 'reasoning' instead of 'reasoning_content'
+            delta.reasoning_content = deltaRecord.reasoning;
+          } else if (Array.isArray(deltaRecord.reasoning_details)) {
+            // StepFun/OpenRouter: reasoning_details[{type:"reasoning.text", text:"..."}]
+            const parts: string[] = [];
+            for (const detail of deltaRecord.reasoning_details) {
+              const d = detail && typeof detail === "object" ? (detail as JsonRecord) : null;
+              if (!d) continue;
+              const text =
+                typeof d.text === "string"
+                  ? d.text
+                  : typeof d.content === "string"
+                    ? d.content
+                    : "";
+              if (text) parts.push(text);
+            }
+            if (parts.length > 0) {
+              delta.reasoning_content = parts.join("");
+            }
           }
           if (deltaRecord.tool_calls !== undefined) delta.tool_calls = deltaRecord.tool_calls;
           if (deltaRecord.function_call !== undefined)

open-sse/translator/response/openai-to-claude.ts

@@ -93,7 +93,18 @@ export function openaiToClaudeResponse(chunk, state) {
   }
 
   // Handle reasoning_content (thinking) - GLM, DeepSeek, etc.
-  const reasoningContent = delta?.reasoning_content || delta?.reasoning;
+  // Also supports 'reasoning' field alias and reasoning_details[] (StepFun/OpenRouter)
+  let reasoningContent = delta?.reasoning_content || delta?.reasoning;
+  if (!reasoningContent && Array.isArray(delta?.reasoning_details)) {
+    const parts: string[] = [];
+    for (const detail of delta.reasoning_details) {
+      if (detail && typeof detail === "object") {
+        const text = detail.text || detail.content;
+        if (typeof text === "string" && text) parts.push(text);
+      }
+    }
+    if (parts.length > 0) reasoningContent = parts.join("");
+  }
   if (reasoningContent) {
     stopTextBlock(state, results);
 

open-sse/utils/usageTracking.ts

@@ -66,12 +66,47 @@ export function addBufferToUsage(usage) {
 export function filterUsageForFormat(usage, targetFormat) {
   if (!usage || typeof usage !== "object") return usage;
 
+  // Cross-map between Claude-style and OpenAI-style field names before filtering.
+  // Some providers return input_tokens/output_tokens even when using OpenAI format.
+  const convertedUsage = { ...usage };
+  if (targetFormat === FORMATS.CLAUDE || targetFormat === FORMATS.OPENAI_RESPONSES) {
+    // OpenAI → Claude: prompt_tokens → input_tokens
+    if (convertedUsage.prompt_tokens !== undefined && convertedUsage.input_tokens === undefined) {
+      convertedUsage.input_tokens = convertedUsage.prompt_tokens;
+    }
+    if (
+      convertedUsage.completion_tokens !== undefined &&
+      convertedUsage.output_tokens === undefined
+    ) {
+      convertedUsage.output_tokens = convertedUsage.completion_tokens;
+    }
+  } else {
+    // Claude → OpenAI: input_tokens → prompt_tokens
+    if (convertedUsage.input_tokens !== undefined && convertedUsage.prompt_tokens === undefined) {
+      convertedUsage.prompt_tokens = convertedUsage.input_tokens;
+    }
+    if (
+      convertedUsage.output_tokens !== undefined &&
+      convertedUsage.completion_tokens === undefined
+    ) {
+      convertedUsage.completion_tokens = convertedUsage.output_tokens;
+    }
+    // Ensure total_tokens is set
+    if (
+      convertedUsage.total_tokens === undefined &&
+      convertedUsage.prompt_tokens !== undefined &&
+      convertedUsage.completion_tokens !== undefined
+    ) {
+      convertedUsage.total_tokens = convertedUsage.prompt_tokens + convertedUsage.completion_tokens;
+    }
+  }
+
   // Helper to pick only defined fields from usage
   const pickFields = (fields) => {
     const filtered = {};
     for (const field of fields) {
-      if (usage[field] !== undefined) {
-        filtered[field] = usage[field];
+      if (convertedUsage[field] !== undefined) {
+        filtered[field] = convertedUsage[field];
       }
     }
     return filtered;
@@ -230,10 +265,14 @@ export function extractUsage(chunk) {
   }
 
   // OpenAI format
-  if (chunk.usage && typeof chunk.usage === "object" && chunk.usage.prompt_tokens !== undefined) {
+  if (
+    chunk.usage &&
+    typeof chunk.usage === "object" &&
+    (chunk.usage.prompt_tokens !== undefined || chunk.usage.input_tokens !== undefined)
+  ) {
     return normalizeUsage({
-      prompt_tokens: chunk.usage.prompt_tokens,
-      completion_tokens: chunk.usage.completion_tokens || 0,
+      prompt_tokens: chunk.usage.prompt_tokens ?? chunk.usage.input_tokens ?? 0,
+      completion_tokens: chunk.usage.completion_tokens ?? chunk.usage.output_tokens ?? 0,
       cached_tokens: chunk.usage.prompt_tokens_details?.cached_tokens,
       reasoning_tokens: chunk.usage.completion_tokens_details?.reasoning_tokens,
     });