feat(tui,gemini): implement verbose transfer and url image fetch

src/models/gemini.ts

@@ -44,7 +44,7 @@ export class GeminiClient implements ModelClient {
 
   async chat(request: ChatRequest): Promise<ChatResponse> {
     const model = this.getModel(request);
-    const contents = convertMessages(request.messages);
+    const contents = await convertMessages(request.messages);
 
     const result = await model.generateContent({ contents });
     const response = result.response;
@@ -100,7 +100,7 @@ export class GeminiClient implements ModelClient {
 
   async *chatStream(request: ChatRequest): AsyncIterable<ChatStreamEvent> {
     const model = this.getModel(request);
-    const contents = convertMessages(request.messages);
+    const contents = await convertMessages(request.messages);
 
     try {
       const result = await model.generateContentStream({ contents });
@@ -162,8 +162,8 @@ export class GeminiClient implements ModelClient {
 }
 
 /** Convert Flynn's Message[] to Gemini Content[] format, including multimodal parts */
-function convertMessages(messages: Message[]): Content[] {
-  return messages.map(m => {
+async function convertMessages(messages: Message[]): Promise<Content[]> {
+  return Promise.all(messages.map(async (m) => {
     const role = m.role === 'assistant' ? 'model' : 'user';
 
     if (typeof m.content === 'string') {
@@ -171,7 +171,7 @@ function convertMessages(messages: Message[]): Content[] {
     }
 
     // Multimodal content — convert each part
-    const parts: Part[] = m.content.map(part => {
+    const parts = await Promise.all(m.content.map(async (part): Promise<Part> => {
       if (part.type === 'text') {
         return { text: part.text };
       }
@@ -184,8 +184,12 @@ function convertMessages(messages: Message[]): Content[] {
             },
           };
         }
-        // URL-based images — Gemini doesn't natively support URL refs in inline data,
-        // so we pass as a text description. In production, you'd want to fetch + base64 encode.
+        if (part.source.type === 'url' && part.source.url) {
+          const inlineImage = await fetchImageAsInlineData(part.source.url, part.source.media_type);
+          if (inlineImage) {
+            return inlineImage;
+          }
+        }
         return { text: `[Image: ${part.source.url ?? 'unavailable'}]` };
       }
       // Audio part — Gemini supports native audio via inlineData (same format as images)
@@ -198,10 +202,33 @@ function convertMessages(messages: Message[]): Content[] {
         };
       }
       return { text: JSON.stringify(part) };
-    });
+    }));
 
     return { role, parts };
-  });
+  }));
+}
+
+async function fetchImageAsInlineData(url: string, fallbackMimeType: string): Promise<Part | null> {
+  try {
+    const response = await fetch(url);
+    if (!response.ok) {
+      return null;
+    }
+    const mimeTypeHeader = response.headers.get('content-type');
+    const mimeType = mimeTypeHeader ? mimeTypeHeader.split(';')[0].trim() : fallbackMimeType;
+    const data = Buffer.from(await response.arrayBuffer()).toString('base64');
+    if (!data) {
+      return null;
+    }
+    return {
+      inlineData: {
+        mimeType,
+        data,
+      },
+    };
+  } catch {
+    return null;
+  }
 }
 
 /** Convert Flynn's ToolDefinition to Gemini FunctionDeclaration format */