expose shell metadata in call responses

src/ipython_demo/models.py

@@ -12,6 +12,8 @@ CallEventKind = Literal[
     "error",
 ]
 
+ShellStatus = Literal["ready", "running", "error"]
+
 
 @dataclass
 class CallEvent:
@@ -55,3 +57,17 @@ class CallResponse:
     collapsed: bool
     result: CallResult
     events: list[CallEvent]
+    shell: ShellInfo
+
+
+@dataclass
+class ShellInfo:
+    """Frontend-safe snapshot describing one persistent shell."""
+
+    shell_id: str
+    name: str
+    status: ShellStatus
+    execution_count: int
+    created_at: str
+    last_used_at: str | None
+    capabilities: tuple[str, ...]