Apply remaining review findings (L-e, L-f)

- L-e: route terminal file drops purely by a bounds hit-test instead of
  the `active` flag. Inactive panes are display:none (zero-size rect) so
  they never match; a zero-size guard makes that explicit. Correct for
  the current tabbed layout and future-proof for split panes, where a
  drop on a visible-but-unfocused pane previously matched no handler.
- L-f: stream the dropped file straight into the upload tar inside a
  blocking task (new exec::upload_host_file_to_container) instead of
  reading the whole file into a Vec and then re-packing it. Peak memory
  drops from ~2x to ~1x the file size, and the synchronous file IO no
  longer runs on the async worker.

cargo check / tsc / vitest all pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src-tauri/src/commands/terminal_commands.rs

@@ -203,8 +203,8 @@ pub async fn upload_host_file_to_terminal(
         return Err(format!("{} is a directory — drop individual files", host_path));
     }
 
-    // Guard against ballooning host RAM: the file is read fully into memory and
-    // then re-packed into an in-memory tar, so cap the size of a dropped file.
+    // Guard against ballooning host RAM: the file is packed into an in-memory
+    // tar before upload, so cap the size of a dropped file.
     const MAX_DROP_BYTES: u64 = 256 * 1024 * 1024; // 256 MiB
     if meta.len() > MAX_DROP_BYTES {
         return Err(format!(
@@ -214,10 +214,6 @@ pub async fn upload_host_file_to_terminal(
         ));
     }
 
-    let data = tokio::fs::read(&host_path)
-        .await
-        .map_err(|e| format!("Failed to read {}: {}", host_path, e))?;
-
     let base = std::path::Path::new(&host_path)
         .file_name()
         .map(|s| s.to_string_lossy().to_string())
@@ -233,10 +229,7 @@ pub async fn upload_host_file_to_terminal(
     .await?;
 
     let file_name = format!("triple-c-drops/{}", base);
-    state
-        .exec_manager
-        .write_file_to_container(&container_id, &file_name, &data)
-        .await
+    crate::docker::exec::upload_host_file_to_container(&container_id, &host_path, &file_name).await
 }
 
 #[tauri::command]

app/src-tauri/src/docker/exec.rs

@@ -279,6 +279,63 @@ impl ExecSessionManager {
     }
 }
 
+/// Upload a host file into the container's `/tmp` under `dest_name`, building the
+/// tar archive by streaming from the file inside a blocking task. Unlike reading
+/// the whole file into a `Vec` and then handing it to `write_file_to_container`
+/// (which holds two full-size copies — the data and the tar), this keeps only
+/// the single tar buffer, and the synchronous file IO runs off the async worker.
+/// Returns the in-container path (`/tmp/<dest_name>`).
+pub async fn upload_host_file_to_container(
+    container_id: &str,
+    host_path: &str,
+    dest_name: &str,
+) -> Result<String, String> {
+    let host_path = host_path.to_string();
+    let dest_name = dest_name.to_string();
+    let dest_for_blk = dest_name.clone();
+
+    let tar_buf = tokio::task::spawn_blocking(move || -> Result<Vec<u8>, String> {
+        let mut file = std::fs::File::open(&host_path)
+            .map_err(|e| format!("Failed to read {}: {}", host_path, e))?;
+        let size = file
+            .metadata()
+            .map_err(|e| format!("Failed to stat {}: {}", host_path, e))?
+            .len();
+        let mut tar_buf = Vec::new();
+        {
+            let mut builder = tar::Builder::new(&mut tar_buf);
+            let mut header = tar::Header::new_gnu();
+            header.set_size(size);
+            header.set_mode(0o644);
+            header.set_cksum();
+            builder
+                .append_data(&mut header, &dest_for_blk, &mut file)
+                .map_err(|e| format!("Failed to create tar entry: {}", e))?;
+            builder
+                .finish()
+                .map_err(|e| format!("Failed to finalize tar: {}", e))?;
+        }
+        Ok(tar_buf)
+    })
+    .await
+    .map_err(|e| format!("Upload task panicked: {}", e))??;
+
+    let docker = get_docker()?;
+    docker
+        .upload_to_container(
+            container_id,
+            Some(UploadToContainerOptions {
+                path: "/tmp".to_string(),
+                ..Default::default()
+            }),
+            tar_buf.into(),
+        )
+        .await
+        .map_err(|e| format!("Failed to upload file to container: {}", e))?;
+
+    Ok(format!("/tmp/{}", dest_name))
+}
+
 /// Run a one-shot (non-interactive) exec command in a container and collect stdout.
 pub async fn exec_oneshot(container_id: &str, cmd: Vec<String>) -> Result<String, String> {
     exec_oneshot_env(container_id, cmd, Vec::new()).await

app/src/components/terminal/TerminalView.tsx

@@ -57,15 +57,18 @@ export default function TerminalView({ sessionId, active }: Props) {
   // in-container paths typed into the prompt so Claude Code can read them.
   // Tauri intercepts OS file drops at the webview level, so we use
   // onDragDropEvent (HTML5 ondrop on the element wouldn't expose file paths).
-  // The listener is window-wide, so we guard on `active` + a hit-test against
-  // this terminal's bounds to ignore drops meant for another pane.
+  // The listener is window-wide, so we route purely by a hit-test against this
+  // terminal's bounds: the pane the drop lands on handles it. Inactive panes are
+  // `display:none` (zero-size rect) so they never match — this works for the
+  // current tabbed layout and would also do the right thing with split panes.
   useEffect(() => {
     let unlisten: (() => void) | undefined;
     let cancelled = false;
 
     const insideThisTerminal = (pos: { x: number; y: number }): boolean => {
       const rect = containerRef.current?.getBoundingClientRect();
-      if (!rect) return false;
+      // A hidden (display:none) pane has a zero-size rect — never a drop target.
+      if (!rect || rect.width === 0 || rect.height === 0) return false;
       const dpr = window.devicePixelRatio || 1;
       const x = pos.x / dpr;
       const y = pos.y / dpr;
@@ -80,7 +83,6 @@ export default function TerminalView({ sessionId, active }: Props) {
     (async () => {
       const un = await getCurrentWebview().onDragDropEvent(async (event) => {
         if (event.payload.type !== "drop") return;
-        if (!activeRef.current) return;
         if (!insideThisTerminal(event.payload.position)) return;
 
         const paths = event.payload.paths ?? [];