Split control messages by scope: the root ctl takes the session's builtins and reads the settings, a pane's ctl its own

Every builtin could only be clicked, or written to exec, and the settings
could be read only as the Config window's prose. acme keeps window verbs on
a window's ctl, and webfs and upas/fs keep session settings on a root ctl.
Each builtin now declares its scope (scope = .session; settings are all
session, the rest pane), read by the registry. The root /ctl takes session
builtins and reads every setting in the words a write takes, so its read
written back changes nothing (panel and scene effects now take on/off like
the toggles, to make that true); a pane's ctl takes the pane's builtins
beside get, lock and unlock. Writes are checked whole and refused in Plan
9's ctl words (unknown control message "X", wrong #args ...), which 9ns
now maps to EINVAL (cloud9 re-pinned at a8c7a715). A builtin that would
prompt for its argument fails the write instead, and a refusal is answered
at once, not after the frame.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 19 insertions, 1 deletions

diff --git a/test/fs.py b/test/fs.py
index ccf3eb89..82d7cf0b 100644
--- a/test/fs.py
+++ b/test/fs.py
@@ -245,6 +245,24 @@ def discovery(binary, embedded=False):
                 raise AssertionError('focus took a serial no pane has')
             except OSError as refused:
                 assert 'no such window' in str(refused), refused
+            # /ctl reads the settings as a write takes them and takes the
+            # session's builtins; a pane's ctl takes the pane's.
+            settings = client.read('/ctl')
+            assert b'Verbose ' in settings and b'Platform' not in settings, settings
+            client.write('/ctl', settings)
+            assert client.read('/ctl') == settings
+            client.write('/ctl', b'Verbose off\n')
+            assert b'Verbose off\n' in client.read('/ctl')
+            for path, line, why in (('/ctl', b'Del\n', 'not a session control message "Del"'),
+                                    ('/ctl', b'Nope 3\n', 'unknown control message "Nope 3"'),
+                                    (f'/pane/{first}/ctl', b'Newcol\n', 'not a window control message "Newcol"')):
+                try:
+                    client.write(path, line)
+                    raise AssertionError(f'{path} took {line!r}')
+                except OSError as refused:
+                    assert why in str(refused), refused
+            client.write(f'/pane/{first}/ctl', b'Msg said through ctl\n')
+            assert 'said through ctl' in ''.join(cell[0] for cell in client.screen()['cells'])
             assert set(client.list('/pane')) == {'new', str(fixture), str(first), str(second)}
             client.write(f'/pane/{first}/body', b'first pane', truncate=True)
             assert client.read(f'/pane/{first}/body') == b'first pane'
@@ -315,7 +333,7 @@ def discovery(binary, embedded=False):
                 assert client.read('/src/pardes.zig').startswith(b'const std')
                 assert client.stat('/src/pardes.zig')['mode'] == 0o444
                 assert b'pub const Pardes' in client.read(f'/pane/{look(client, "/virtual/src/pardes.zig")}/body')
-    print('9P discovery: listing/stat/find are inert; new, remove, look, exec, name, sel, log, ctl lock and focus behave')
+    print('9P discovery: listing/stat/find are inert; new, remove, look, exec, name, sel, log, ctl lock, focus and the ctl split behave')
 
 
 def run_file(binary):