fix(tui): always call input.detect_drop for reliable image attachment

Remove frontend regex pre-check that truncated paths containing spaces,
quotes, or Windows drive letters. Backend _detect_file_drop correctly
handles these patterns. This fixes image attachment for common filenames
like "Screenshot 2026-04-29.png".

Add tests:
- test_input_detect_drop_path_with_spaces: attaches image with spaces in name
- test_input_detect_drop_path_with_spaces_and_remainder: remainder handling

Also restored missing  in test_rollback_restore_resolves_number_and_file_path.

Scope: tui, vision, tests

tests/test_tui_gateway_server.py

@@ -1923,6 +1923,55 @@ def test_input_detect_drop_attaches_image(monkeypatch):
     assert resp["result"]["text"] == "[User attached image: cat.png]"
 
 
+def test_input_detect_drop_path_with_spaces(tmp_path):
+    """input.detect_drop correctly handles image paths containing spaces."""
+    # Create a minimal PNG file with a space in its name
+    img = tmp_path / "screenshot with spaces.png"
+    img.write_bytes(b"\x89PNG\r\n\x1a\n")  # valid PNG header
+
+    server._sessions["sid"] = _session()
+
+    resp = server.handle_request(
+        {
+            "id": "2",
+            "method": "input.detect_drop",
+            "params": {"session_id": "sid", "text": str(img)},
+        }
+    )
+
+    assert resp["result"]["matched"] is True
+    assert resp["result"]["is_image"] is True
+    assert resp["result"]["path"] == str(img)
+    assert resp["result"]["text"] == f"[User attached image: {img.name}]"
+    # Verify attachment was recorded in the session
+    assert len(server._sessions["sid"]["attached_images"]) == 1
+    assert server._sessions["sid"]["attached_images"][0] == str(img)
+
+
+def test_input_detect_drop_path_with_spaces_and_remainder(tmp_path):
+    """input.detect_drop splits remainder when path contains spaces."""
+    img = tmp_path / "photo with space.jpg"
+    img.write_bytes(b"\xff\xd8\xff" + b"fakejpeg")  # minimal-ish JPEG header
+
+    server._sessions["sid"] = _session()
+
+    user_input = f"{img} describe this image"
+    resp = server.handle_request(
+        {
+            "id": "3",
+            "method": "input.detect_drop",
+            "params": {"session_id": "sid", "text": user_input},
+        }
+    )
+
+    assert resp["result"]["matched"] is True
+    assert resp["result"]["is_image"] is True
+    assert resp["result"]["path"] == str(img)
+    # Remainder becomes the text sent to the model
+    assert resp["result"]["text"] == "describe this image"
+    assert server._sessions["sid"]["attached_images"][0] == str(img)
+
+
 def test_rollback_restore_resolves_number_and_file_path():
     calls = {}
 

ui-tui/src/app/useSubmission.ts

@@ -126,13 +126,9 @@ export function useSubmission(opts: UseSubmissionOptions) {
         return sys('session not ready yet')
       }
 
-      // Plain prompts are the common path and should not pay an extra RPC
+      // Always ask the backend whether this looks like a file drop.
-      // before prompt.submit. File-drop detection still runs for absolute,
+      // The backend's _detect_file_drop handles paths with spaces, quotes,
-      // tilde, file://, and explicit relative paths.
+      // Windows drive letters, and escaped characters correctly.
-      if (!looksLikeSlashCommand(text) && !/(?:^|\s)(?:file:\/\/|~\/|\.?\.\/|\/)[^\s]+/.test(text)) {
-        return startSubmit(text, expand(text), showUserMessage)
-      }
-
       gw.request<InputDetectDropResponse>('input.detect_drop', { session_id: sid, text })
         .then(r => {
           if (!r?.matched) {