Reload syntax on saving

babi/file.py

@@ -221,6 +221,21 @@ def __init__(
         self.selection = Selection()
         self._file_hls: tuple[FileHL, ...] = ()
 
+    def refresh_syntax(self) -> None:
+        file_hls = []
+        for factory in self._hl_factories:
+            if self.filename is not None:
+                hl = factory.file_highlighter(self.filename, self.buf[0])
+                file_hls.append(hl)
+            else:
+                file_hls.append(factory.blank_file_highlighter())
+        self._file_hls = (
+            *file_hls,
+            self._trailing_whitespace, self._replace_hl, self.selection,
+        )
+        for file_hl in self._file_hls:
+            file_hl.register_callbacks(self.buf)
+
     def ensure_loaded(
             self,
             status: Status,
@@ -255,20 +270,7 @@ def ensure_loaded(
             status.update(f'mixed newlines will be converted to {self.nl!r}')
             self.modified = True
 
-        file_hls = []
-        for factory in self._hl_factories:
-            if self.filename is not None:
-                hl = factory.file_highlighter(self.filename, self.buf[0])
-                file_hls.append(hl)
-            else:
-                file_hls.append(factory.blank_file_highlighter())
-        self._file_hls = (
-            *file_hls,
-            self._trailing_whitespace, self._replace_hl, self.selection,
-        )
-        for file_hl in self._file_hls:
-            file_hl.register_callbacks(self.buf)
-
+        self.refresh_syntax()
         self.go_to_line(self.initial_line, margin)
 
     def __repr__(self) -> str:

babi/screen.py

@@ -565,6 +565,16 @@ def save(self) -> PromptResult | None:
             else:
                 self.file.filename = filename
 
+        if os.path.exists(self.file.filename):
+            with open(self.file.filename) as f:
+                x = f.readline()[:-1]
+            refresh_syntax = (
+                x != self.file.buf[0] and
+                self.file.buf[0].startswith('#!/') or x.startswith('#!/')
+            )
+        else:
+            refresh_syntax = True
+
         if not os.path.isfile(self.file.filename):
             sha256: str | None = None
         else:
@@ -596,6 +606,10 @@ def save(self) -> PromptResult | None:
         lines = 'lines' if num_lines != 1 else 'line'
         self.status.update(f'saved! ({num_lines} {lines} written)')
         self.file.reset_modified_state()
+
+        if refresh_syntax:
+            self.file.refresh_syntax()
+
         return None
 
     def save_filename(self) -> PromptResult | None: