diff --git a/.changeset/fix-non-ascii-filename.md b/.changeset/fix-non-ascii-filename.md
new file mode 100644
index 0000000..11bc46a
--- /dev/null
+++ b/.changeset/fix-non-ascii-filename.md
@@ -0,0 +1,9 @@
+---
+"@agent-wechat/agent-server": patch
+---
+
+fix: handle non-ASCII filenames in file send
+
+- Use portable `iconv` check instead of GNU-only `grep -P` for non-ASCII path detection in paste-file
+- Sanitize filenames to ASCII-safe temp paths so WeChat (Qt/POSIX locale) can open them
+- Return proper error responses on base64 decode or file write failures instead of silent success
diff --git a/docker/tools/paste-file b/docker/tools/paste-file
index 4c0cc20..ba0c25a 100755
--- a/docker/tools/paste-file
+++ b/docker/tools/paste-file
@@ -3,6 +3,9 @@
 # Usage: paste-file <file-path>
 #
 # Sets clipboard to text/uri-list so Qt apps treat it as a file paste.
+# If the path contains non-ASCII characters (e.g. CJK filenames), the
+# file is copied to an ASCII-safe temp path first, because WeChat's Qt
+# build in POSIX locale cannot resolve non-ASCII file:// URIs.
 
 set -euo pipefail
 
@@ -21,6 +24,18 @@ fi
 # Convert to absolute path
 ABS_PATH="$(realpath "$FILE")"
 
+# If the path contains non-ASCII characters, copy to an ASCII-safe temp
+# path.  WeChat (Qt) under POSIX locale silently fails to open file://
+# URIs whose path includes non-ASCII bytes.
+if ! echo "$ABS_PATH" | iconv -f UTF-8 -t ASCII >/dev/null 2>&1; then
+  EXT="${ABS_PATH##*.}"
+  SAFE_PATH="/tmp/paste_safe_$(date +%s%N).${EXT}"
+  cp "$ABS_PATH" "$SAFE_PATH"
+  ABS_PATH="$SAFE_PATH"
+  # Schedule cleanup after WeChat has had time to read the file
+  (sleep 10 && rm -f "$SAFE_PATH") &
+fi
+
 # Copy file URI to clipboard (backgrounded — xclip blocks until
 # the selection is consumed, so it must run in parallel with the paste)
 echo -n "file://$ABS_PATH" | xclip -selection clipboard -t text/uri-list >/dev/null 2>&1 &
diff --git a/packages/agent-server-rust/src/router/messages.rs b/packages/agent-server-rust/src/router/messages.rs
index 1e40716..1d74de7 100644
--- a/packages/agent-server-rust/src/router/messages.rs
+++ b/packages/agent-server-rust/src/router/messages.rs
@@ -209,11 +209,35 @@ pub async fn send_message(Json(input): Json<SendParams>) -> Json<SendResult> {
     // Decode base64 file to temp file
     let mut file_path: Option<String> = None;
     if let Some(ref f) = input.file {
+        // Sanitize filename: keep ASCII alphanumerics, dot, hyphen, underscore;
+        // replace everything else (including CJK) with underscore so the temp
+        // path stays portable across locales.  The dot is preserved so that
+        // file extensions survive (e.g. "遗憾.pdf" → "__.pdf"); the mangled
+        // stem is acceptable since this is a transient temp path.
+        let safe_name: String = f.filename.chars().map(|c| {
+            if c.is_ascii_alphanumeric() || c == '.' || c == '-' || c == '_' {
+                c
+            } else {
+                '_'
+            }
+        }).collect();
         let path = format!("/tmp/send_file_{}_{}", std::time::SystemTime::now()
-            .duration_since(std::time::UNIX_EPOCH).unwrap_or_default().as_millis(), f.filename);
-        if let Ok(bytes) = base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &f.data) {
-            if std::fs::write(&path, &bytes).is_ok() {
-                file_path = Some(path);
+            .duration_since(std::time::UNIX_EPOCH).unwrap_or_default().as_millis(), safe_name);
+        match base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &f.data) {
+            Ok(bytes) => match std::fs::write(&path, &bytes) {
+                Ok(_) => { file_path = Some(path); }
+                Err(e) => {
+                    return Json(SendResult {
+                        success: false,
+                        error: Some(format!("Failed to write temp file: {e}")),
+                    });
+                }
+            },
+            Err(e) => {
+                return Json(SendResult {
+                    success: false,
+                    error: Some(format!("Failed to decode base64 file data: {e}")),
+                });
             }
         }
     }