fix forked prompt attachments losing file parts (#17815)

packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx

@@ -13,6 +13,7 @@ import { MessageID, PartID } from "@/session/schema"
 import { createStore, produce } from "solid-js/store"
 import { useKeybind } from "@tui/context/keybind"
 import { usePromptHistory, type PromptInfo } from "./history"
+import { assign } from "./part"
 import { usePromptStash } from "./stash"
 import { DialogStash } from "../dialog-stash"
 import { type AutocompleteRef, Autocomplete } from "./autocomplete"
@@ -643,10 +644,7 @@ export function Prompt(props: PromptProps) {
               type: "text",
               text: inputText,
             },
-            ...nonTextParts.map((x) => ({
-              id: PartID.ascending(),
-              ...x,
-            })),
+            ...nonTextParts.map(assign),
           ],
         })
         .catch(() => {})