fix(app): batch multi-file prompt attachments (#18722)

packages/app/src/utils/prompt.test.ts

@@ -0,0 +1,44 @@
+import { describe, expect, test } from "bun:test"
+import type { Part } from "@opencode-ai/sdk/v2"
+import { extractPromptFromParts } from "./prompt"
+
+describe("extractPromptFromParts", () => {
+  test("restores multiple uploaded attachments", () => {
+    const parts = [
+      {
+        id: "text_1",
+        type: "text",
+        text: "check these",
+        sessionID: "ses_1",
+        messageID: "msg_1",
+      },
+      {
+        id: "file_1",
+        type: "file",
+        mime: "image/png",
+        url: "data:image/png;base64,AAA",
+        filename: "a.png",
+        sessionID: "ses_1",
+        messageID: "msg_1",
+      },
+      {
+        id: "file_2",
+        type: "file",
+        mime: "application/pdf",
+        url: "data:application/pdf;base64,BBB",
+        filename: "b.pdf",
+        sessionID: "ses_1",
+        messageID: "msg_1",
+      },
+    ] satisfies Part[]
+
+    const result = extractPromptFromParts(parts)
+
+    expect(result).toHaveLength(3)
+    expect(result[0]).toMatchObject({ type: "text", content: "check these" })
+    expect(result.slice(1)).toMatchObject([
+      { type: "image", filename: "a.png", mime: "image/png", dataUrl: "data:image/png;base64,AAA" },
+      { type: "image", filename: "b.pdf", mime: "application/pdf", dataUrl: "data:application/pdf;base64,BBB" },
+    ])
+  })
+})