Fix uploaded images reaching Claude Code empty

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/src/claude_code.rs

@@ -361,7 +361,12 @@ fn save_images(cwd: &str, parts: &[Part]) -> Vec<String> {
     let mut out = Vec::new();
     for (i, p) in parts.iter().enumerate() {
         let Part::Image { image } = p else { continue };
+        // An image without bytes (an unresolved reference) would become an empty file.
         let Ok(bytes) = base64::engine::general_purpose::STANDARD.decode(&image.data) else { continue };
+        if bytes.is_empty() {
+            tracing::warn!("claude code: image {i} of the message has no data – not saved");
+            continue;
+        }
         let ext = image.media_type.split('/').nth(1).unwrap_or("png").split('+').next().unwrap_or("png");
         let path = dir.join(format!("chat-{}-{i}.{ext}", now_ms()));
         if std::fs::create_dir_all(&dir).is_ok() {
@@ -379,7 +384,8 @@ pub async fn run(app: Arc<App>, session_id: &str, cancel: CancellationToken) ->
     let session = app.session(session_id)?;
     let owner = session.owner_id.clone();
     let model_id = session.model.strip_prefix("claude-code/").unwrap_or("default").to_string();
-    let history = crate::runner::active_history(app.store.messages(session_id)?);
+    // With the bytes of the images filled in (they are stored as references).
+    let history = crate::runner::active_history(app.store.messages_for_model(session_id)?);
     let Some(last_user) = history.iter().rposition(|m| m.role == Role::User && m.parts.iter().any(|p| matches!(p, Part::Text { .. } | Part::Image { .. }))) else {
         bail!("nothing to do: no user message");
     };
@@ -956,6 +962,21 @@ pub async fn update() -> Result<String> {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn uploaded_images_are_saved_with_their_bytes_only() {
+        let dir = std::env::temp_dir().join(format!("cc-uploads-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        let parts = vec![
+            Part::Image { image: ImageData { media_type: "image/png".into(), data: "QUJD".into(), blob: None, size: None } },
+            // A reference whose bytes were not filled in: must not become an empty file.
+            Part::Image { image: ImageData { media_type: "image/png".into(), data: String::new(), blob: Some("x".into()), size: None } },
+        ];
+        let saved = save_images(&dir.display().to_string(), &parts);
+        assert_eq!(saved.len(), 1);
+        assert_eq!(std::fs::read(&saved[0]).unwrap(), b"ABC");
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+
     #[test]
     fn questions_roundtrip_with_the_cli_format() {
         let input = json!({"questions": [