Add Remote Braille IPC to the host and both SDKs

remote.braille requests and events carry a typed op under a
braille-stream lease: the controller's width and gestures for a
controlled reader, rendered cells back to its child, and cells, local
geometry and display gestures for a controller. Direction is validated
per role; a full mailbox revokes the lease. No display owner is
attached yet.

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

sdk/python/cthulhu_tentacle/session.py

@@ -166,6 +166,48 @@ def valid_remote_focus_request(request):
         return False
 
 
+def valid_remote_braille(value, role=None, request=None):
+    """Validate one Remote Braille operation; role/request also check direction."""
+    try:
+        _fields(value, ("op",), ("width", "gesture", "index", "cells"))
+        op = value["op"]
+        width, gesture, index = value.get("width", 0), value.get("gesture", ""), value.get("index", 0)
+        cells = value.get("cells")
+        if type(width) is not int or type(index) is not int or not isinstance(gesture, str):
+            return False
+        if op in ("size", "geometry"):
+            ok = 0 <= width <= 4096 and gesture == "" and index == 0 and cells is None
+        elif op == "gesture":
+            ok = (width == 0 and cells is None
+                  and (gesture in ("pan-left", "pan-right") and index == 0
+                       or gesture == "route" and 0 <= index < 4096))
+        elif op == "cells":
+            ok = (isinstance(cells, list) and 1 <= len(cells) <= 4096
+                  and all(type(cell) is int and 0 <= cell <= 255 for cell in cells)
+                  and width == 0 and gesture == "" and index == 0)
+        else:
+            return False
+        if not ok or role is None:
+            return ok
+        if role == "controlled":
+            return op in ("size", "gesture") if request else op == "cells"
+        if role == "controller":
+            return (op == "cells" or op == "geometry" and width == 0) if request else op in ("gesture", "geometry")
+        return False
+    except (ProtocolError, TypeError, ValueError):
+        return False
+
+
+def valid_remote_braille_request(request):
+    """Validate remote.braille parameters; display effects remain owned by core."""
+    try:
+        _fields(request, ("lease", "epoch", "sequence", "braille"))
+        return (_token(request["lease"]) and _positive(request["epoch"])
+                and _positive(request["sequence"]) and valid_remote_braille(request["braille"]))
+    except (ProtocolError, TypeError, ValueError, UnicodeError):
+        return False
+
+
 REMOTE_FOCUS_REASONS = frozenset(("requested", "escape", "local", "unavailable"))
 
 
@@ -358,11 +400,12 @@ class SessionClient:
             waiter.put_nowait(value)
 
     def _event(self, event):
-        _fields(event, ("sequence", "kind", "epoch"), ("action", "lease", "role", "grants", "reason", "speech", "input", "focus"))
+        _fields(event, ("sequence", "kind", "epoch"), ("action", "lease", "role", "grants", "reason", "speech", "input", "focus", "braille"))
         if not _positive(event["sequence"]) or not _positive(event["epoch"]):
             raise ProtocolError("Invalid event sequence")
         if (event["kind"] != "remote.input" and "input" in event
-                or event["kind"] != "remote.focus" and event.get("focus", "") != ""):
+                or event["kind"] != "remote.focus" and event.get("focus", "") != ""
+                or event["kind"] != "remote.braille" and "braille" in event):
             raise ProtocolError("Invalid session event")
         if event["kind"] == "remote.action":
             grants = event.get("grants")
@@ -386,6 +429,14 @@ class SessionClient:
                     or event.get("reason", "") != "" or "speech" in event
                     or not valid_remote_captured_key(event.get("input"))):
                 raise ProtocolError("Invalid input event")
+        elif event["kind"] == "remote.braille":
+            braille = event.get("braille")
+            if (not _token(event.get("lease")) or event.get("action", "") != ""
+                    or event.get("role", "") != "" or event.get("grants", []) != []
+                    or event.get("reason", "") != "" or "speech" in event
+                    or not (valid_remote_braille(braille, "controlled", False)
+                            or valid_remote_braille(braille, "controller", False))):
+                raise ProtocolError("Invalid Braille event")
         elif event["kind"] == "remote.focus":
             if (not _token(event.get("lease")) or event.get("action", "") != ""
                     or event.get("role", "") != "" or event.get("grants", []) != []