feat: native file downloads via DownloadManager

src-tauri/gen/android/app/src/main/java/app/zcode/acp/MainActivity.kt

@@ -1,8 +1,14 @@
 package app.zcode.acp
 
+import android.app.DownloadManager
+import android.content.Context
+import android.net.Uri
 import android.os.Bundle
+import android.os.Environment
+import android.util.Log
 import android.view.View
 import android.view.ViewGroup
+import android.webkit.URLUtil
 import android.webkit.WebView
 import androidx.activity.enableEdgeToEdge
 import androidx.core.view.ViewCompat
@@ -12,6 +18,7 @@ class MainActivity : TauriActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
     enableEdgeToEdge()
     super.onCreate(savedInstanceState)
+    attachDownloadHandler(retriesLeft = 3)
 
     // Edge-to-edge draws the WebView under the system bars, but Android
     // WebView reports env(safe-area-inset-*) as 0. Forward the real insets
@@ -39,6 +46,45 @@ class MainActivity : TauriActivity() {
     }
   }
 
+  // wry registers no DownloadListener: without one the WebView silently
+  // drops every download (fs file URLs with ?dl=1 answer with
+  // Content-Disposition: attachment). Route those into the system
+  // DownloadManager — native notification, lands in public Downloads.
+  private fun attachDownloadHandler(retriesLeft: Int) {
+    val content = findViewById<View>(android.R.id.content)
+    val webView = findWebView(content)
+    if (webView == null) {
+      if (retriesLeft > 0) content.post { attachDownloadHandler(retriesLeft - 1) }
+      return
+    }
+    webView.setDownloadListener { url, _, contentDisposition, mimeType, _ ->
+      val name = fileNameFrom(url, contentDisposition, mimeType)
+      try {
+        val request = DownloadManager.Request(Uri.parse(url))
+          .setTitle(name)
+          .setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
+          .setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, name)
+        (getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager).enqueue(request)
+      } catch (e: Exception) {
+        Log.w("MainActivity", "download enqueue failed: ${e.message}")
+      }
+    }
+  }
+
+  // Prefer the RFC 5987 filename* form (Android's URLUtil only reads the
+  // ASCII fallback), so non-ASCII filenames survive the download.
+  private fun fileNameFrom(url: String, contentDisposition: String?, mimeType: String?): String {
+    if (contentDisposition != null) {
+      val star = Regex("filename\\*=UTF-8''([^;]+)", RegexOption.IGNORE_CASE)
+        .find(contentDisposition)?.groupValues?.getOrNull(1)
+      if (!star.isNullOrBlank()) return Uri.decode(star)
+      val plain = Regex("filename=\"?([^\";]+)\"?", RegexOption.IGNORE_CASE)
+        .find(contentDisposition)?.groupValues?.getOrNull(1)
+      if (!plain.isNullOrBlank()) return plain
+    }
+    return URLUtil.guessFileName(url, contentDisposition, mimeType)
+  }
+
   // The Tauri WebView is not exposed directly; it is the only WebView in the
   // hierarchy, so a lazy walk is safe (insets dispatch happens after layout).
   private fun findWebView(view: View): WebView? {

src/chat/ChatView.tsx

@@ -715,11 +715,14 @@ function Composer() {
         >
           <ImagePlus className="size-5" />
         </button>
+        {/* leading-5 + py-2 = 36px: the single-line input matches the size-9
+            buttons exactly, so items-end aligns them instead of dropping
+            them below the inherited-1.5 text line. */}
         <ComposerPrimitive.Input
           rows={1}
           placeholder={t("chat.inputPlaceholder")}
           onPaste={onPaste}
-          className="max-h-32 min-h-9 flex-1 resize-none bg-transparent py-2 text-[15px] text-ink placeholder:text-faint focus:outline-none"
+          className="max-h-32 min-h-9 flex-1 resize-none bg-transparent py-2 text-[15px] leading-5 text-ink placeholder:text-faint focus:outline-none"
         />
         {/* While a turn runs the Send stays a Send: a draft queues as pending
             (sendPrompt routes it), never a dead button. Cancel stops the turn.

src/components/FileViewer.tsx

@@ -35,7 +35,7 @@ import yaml from "highlight.js/lib/languages/yaml";
 import Lightbox from "yet-another-react-lightbox";
 import Zoom from "yet-another-react-lightbox/plugins/zoom";
 import "yet-another-react-lightbox/styles.css";
-import { ArrowLeft, FileText, Link2, Share2, X } from "lucide-react";
+import { ArrowLeft, Download, FileText, Link2, Share2, X } from "lucide-react";
 import type { FsEntry } from "../lib/types";
 import { useAppStore } from "../store/appStore";
 import { Spinner } from "./Spinner";
@@ -399,6 +399,21 @@ export function FileViewer({ file, path, onClose, onExit }: FileViewerProps) {
     }
   };
 
+  // dl=1 makes the bridge answer with Content-Disposition: attachment, so
+  // the WebView fires its DownloadListener (MainActivity routes it into the
+  // system DownloadManager) instead of navigating to the file. Needs bridge
+  // 0.11.8+; an older bridge ignores the flag and the WebView renders the
+  // file inline — the system back button returns to the app.
+  const downloadFile = () => {
+    if (!url) return;
+    const a = document.createElement("a");
+    a.href = `${url}&dl=1`;
+    a.rel = "noopener";
+    document.body.appendChild(a);
+    a.click();
+    a.remove();
+  };
+
   return (
     <div className="fixed inset-0 z-50 flex flex-col bg-canvas text-ink">
       <header className="flex items-center gap-2 border-b border-hairline px-1.5 pb-2 pt-[max(var(--safe-top),0.5rem)]">
@@ -447,6 +462,13 @@ export function FileViewer({ file, path, onClose, onExit }: FileViewerProps) {
           )}
           {url && (
             <div className="flex items-center gap-2">
+              <button
+                onClick={downloadFile}
+                className="flex items-center gap-1.5 rounded-full bg-blue-600 px-4 py-2 text-sm text-white active:bg-blue-500"
+              >
+                <Download className="size-4" />
+                {t("viewer.download")}
+              </button>
               {canShareFiles && (
                 <button
                   onClick={shareFile}

src/i18n/en.json

@@ -117,6 +117,7 @@
     "retry": "Retry"
   },
   "viewer": {
+    "download": "Download",
     "share": "Share / Save",
     "copyLink": "Copy link",
     "shareFailed": "Share failed",

src/i18n/zh-CN.json

@@ -117,6 +117,7 @@
     "retry": "重试"
   },
   "viewer": {
+    "download": "下载",
     "share": "分享 / 保存",
     "copyLink": "复制链接",
     "shareFailed": "分享失败",