fix: drop reasoning-only messages in interleaved filter

Author: Tom-Ryder

packages/opencode/src/provider/transform.ts

@@ -135,37 +135,31 @@ export namespace ProviderTransform {
 
     if (typeof model.capabilities.interleaved === "object" && model.capabilities.interleaved.field) {
       const field = model.capabilities.interleaved.field
-      return msgs.map((msg) => {
-        if (msg.role === "assistant" && Array.isArray(msg.content)) {
-          const reasoningParts = msg.content.filter((part: any) => part.type === "reasoning")
-          const reasoningText = reasoningParts.map((part: any) => part.text).join("")
-
-          // Filter out reasoning parts from content
-          const filteredContent = msg.content.filter((part: any) => part.type !== "reasoning")
-
-          // Include reasoning_content | reasoning_details directly on the message for all assistant messages
-          if (reasoningText) {
-            return {
-              ...msg,
-              content: filteredContent,
-              providerOptions: {
-                ...msg.providerOptions,
-                openaiCompatible: {
-                  ...(msg.providerOptions as any)?.openaiCompatible,
-                  [field]: reasoningText,
+      return msgs
+        .map((msg) => {
+          if (msg.role === "assistant" && Array.isArray(msg.content)) {
+            const reasoningParts = msg.content.filter((part: any) => part.type === "reasoning")
+            const reasoningText = reasoningParts.map((part: any) => part.text).join("")
+            const filteredContent = msg.content.filter((part: any) => part.type !== "reasoning")
+            if (filteredContent.length === 0) return undefined
+            if (reasoningText) {
+              return {
+                ...msg,
+                content: filteredContent,
+                providerOptions: {
+                  ...msg.providerOptions,
+                  openaiCompatible: {
+                    ...(msg.providerOptions as any)?.openaiCompatible,
+                    [field]: reasoningText,
+                  },
                 },
-              },
+              }
             }
+            return { ...msg, content: filteredContent }
           }
-
-          return {
-            ...msg,
-            content: filteredContent,
-          }
-        }
-
-        return msg
-      })
+          return msg
+        })
+        .filter((msg): msg is ModelMessage => msg !== undefined)
     }
 
     return msgs