fix(opencode): Fixes image reading with OpenAI-compatible providers like Kimi K2.5. (#11323)

Co-authored-by: Aiden Cline <[email protected]>
Co-authored-by: Aiden Cline <[email protected]>

1 files changed, 54 insertions, 2 deletions

diff --git a/packages/opencode/src/session/message-v2.ts b/packages/opencode/src/session/message-v2.ts
index 6358c6c5e..b6043b032 100644
--- a/packages/opencode/src/session/message-v2.ts
+++ b/packages/opencode/src/session/message-v2.ts
@@ -438,6 +438,26 @@ export namespace MessageV2 {
   export function toModelMessages(input: WithParts[], model: Provider.Model): ModelMessage[] {
     const result: UIMessage[] = []
     const toolNames = new Set<string>()
+    // Track media from tool results that need to be injected as user messages
+    // for providers that don't support media in tool results.
+    //
+    // OpenAI-compatible APIs only support string content in tool results, so we need
+    // to extract media and inject as user messages. Other SDKs (anthropic, google,
+    // bedrock) handle type: "content" with media parts natively.
+    //
+    // Only apply this workaround if the model actually supports image input -
+    // otherwise there's no point extracting images.
+    const supportsMediaInToolResults = (() => {
+      if (model.api.npm === "@ai-sdk/anthropic") return true
+      if (model.api.npm === "@ai-sdk/openai") return true
+      if (model.api.npm === "@ai-sdk/amazon-bedrock") return true
+      if (model.api.npm === "@ai-sdk/google-vertex/anthropic") return true
+      if (model.api.npm === "@ai-sdk/google") {
+        const id = model.api.id.toLowerCase()
+        return id.includes("gemini-3") && !id.includes("gemini-2")
+      }
+      return false
+    })()
 
     const toModelOutput = (output: unknown) => {
       if (typeof output === "string") {
@@ -514,6 +534,7 @@ export namespace MessageV2 {
 
       if (msg.info.role === "assistant") {
         const differentModel = `${model.providerID}/${model.id}` !== `${msg.info.providerID}/${msg.info.modelID}`
+        const media: Array<{ mime: string; url: string }> = []
 
         if (
           msg.info.error &&
@@ -545,11 +566,23 @@ export namespace MessageV2 {
             if (part.state.status === "completed") {
               const outputText = part.state.time.compacted ? "[Old tool result content cleared]" : part.state.output
               const attachments = part.state.time.compacted ? [] : (part.state.attachments ?? [])
+
+              // For providers that don't support media in tool results, extract media files
+              // (images, PDFs) to be sent as a separate user message
+              const isMediaAttachment = (a: { mime: string }) =>
+                a.mime.startsWith("image/") || a.mime === "application/pdf"
+              const mediaAttachments = attachments.filter(isMediaAttachment)
+              const nonMediaAttachments = attachments.filter((a) => !isMediaAttachment(a))
+              if (!supportsMediaInToolResults && mediaAttachments.length > 0) {
+                media.push(...mediaAttachments)
+              }
+              const finalAttachments = supportsMediaInToolResults ? attachments : nonMediaAttachments
+
               const output =
-                attachments.length > 0
+                finalAttachments.length > 0
                   ? {
                       text: outputText,
-                      attachments,
+                      attachments: finalAttachments,
                     }
                   : outputText
 
@@ -593,6 +626,25 @@ export namespace MessageV2 {
         }
         if (assistantMessage.parts.length > 0) {
           result.push(assistantMessage)
+          // Inject pending media as a user message for providers that don't support
+          // media (images, PDFs) in tool results
+          if (media.length > 0) {
+            result.push({
+              id: Identifier.ascending("message"),
+              role: "user",
+              parts: [
+                {
+                  type: "text" as const,
+                  text: "Attached image(s) from tool result:",
+                },
+                ...media.map((attachment) => ({
+                  type: "file" as const,
+                  url: attachment.url,
+                  mediaType: attachment.mime,
+                })),
+              ],
+            })
+          }
         }
       }
     }