fix(app): support text attachments (#17335)

packages/opencode/src/session/prompt.ts

@@ -47,6 +47,7 @@ import { LLM } from "./llm"
 import { iife } from "@/util/iife"
 import { Shell } from "@/shell/shell"
 import { Truncate } from "@/tool/truncation"
+import { decodeDataUrl } from "@/util/data-url"
 
 // @ts-ignore
 globalThis.AI_SDK_LOG_WARNINGS = false
@@ -1079,7 +1080,7 @@ export namespace SessionPrompt {
                     sessionID: input.sessionID,
                     type: "text",
                     synthetic: true,
-                    text: Buffer.from(part.url, "base64url").toString(),
+                    text: decodeDataUrl(part.url),
                   },
                   {
                     ...part,

packages/opencode/src/util/data-url.ts

@@ -0,0 +1,9 @@
+export function decodeDataUrl(url: string) {
+  const idx = url.indexOf(",")
+  if (idx === -1) return ""
+
+  const head = url.slice(0, idx)
+  const body = url.slice(idx + 1)
+  if (head.includes(";base64")) return Buffer.from(body, "base64").toString("utf8")
+  return decodeURIComponent(body)
+}

packages/opencode/test/util/data-url.test.ts

@@ -0,0 +1,14 @@
+import { describe, expect, test } from "bun:test"
+import { decodeDataUrl } from "../../src/util/data-url"
+
+describe("decodeDataUrl", () => {
+  test("decodes base64 data URLs", () => {
+    const body = '{\n  "ok": true\n}\n'
+    const url = `data:text/plain;base64,${Buffer.from(body).toString("base64")}`
+    expect(decodeDataUrl(url)).toBe(body)
+  })
+
+  test("decodes plain data URLs", () => {
+    expect(decodeDataUrl("data:text/plain,hello%20world")).toBe("hello world")
+  })
+})