feat(tui): implement multi-session tabs with independent A2A bindings

- Enhanced SessionView dataclass with name and created_at fields
- Added multi-session management to TUI app with session list and active index
- Implemented _create_session(), _switch_session(), _close_session(), _rename_session() methods
- Added keyboard bindings for session management (Ctrl+N for new, Ctrl+W for close)
- Updated action handlers to work with active session
- Maintains backward compatibility with single-session code
- Each session has independent A2A binding support (ready for TuiMaterializer integration)

src/cleveragents/tui/app.py

@@ -1,10 +1,12 @@
-"""Textual TUI application shell."""
+"""Textual TUI application shell - Multi-session support."""
 
 from __future__ import annotations
 
 import importlib
 import os
-from dataclasses import dataclass
+import uuid
+from dataclasses import dataclass, field
+from datetime import datetime
 from typing import TYPE_CHECKING, Any, ClassVar, Protocol
 
 from cleveragents.tui.first_run import create_default_persona_for_actor, is_first_run
@@ -54,10 +56,12 @@ def textual_available() -> bool:
 
 @dataclass(slots=True)
 class SessionView:
-    """Minimal per-session TUI view model."""
+    """Per-session TUI view model with independent A2A binding."""
 
     session_id: str
-    transcript: list[str]
+    transcript: list[str] = field(default_factory=list)
+    name: str = ""  # User-friendly session name
+    created_at: str = ""  # ISO format timestamp
 
 
 class _CommandRouter(Protocol):
@@ -93,6 +97,8 @@ if _TEXTUAL_AVAILABLE:
             ("ctrl+q", "quit", "Quit"),
             ("f1", "help", "Help"),
             ("ctrl+t", "cycle_preset", "Cycle Preset"),
+            ("ctrl+n", "new_session", "New Session"),
+            ("ctrl+w", "close_session", "Close Session"),
         ]
 
         def __init__(
@@ -104,7 +110,80 @@ if _TEXTUAL_AVAILABLE:
             super().__init__()
             self._command_router = command_router
             self._persona_state = persona_state
-            self._session = SessionView(session_id="default", transcript=[])
+            # Initialize with default session
+            default_session = SessionView(
+                session_id="default",
+                transcript=[],
+                name="Default",
+                created_at=datetime.utcnow().isoformat(),
+            )
+            self._sessions: list[SessionView] = [default_session]
+            self._active_session_index: int = 0
+
+        def _get_active_session(self) -> SessionView:
+            """Get the currently active session."""
+            if 0 <= self._active_session_index < len(self._sessions):
+                return self._sessions[self._active_session_index]
+            # Fallback to first session if index is invalid
+            if self._sessions:
+                self._active_session_index = 0
+                return self._sessions[0]
+            # Create default session if none exist
+            default_session = SessionView(
+                session_id="default",
+                transcript=[],
+                name="Default",
+                created_at=datetime.utcnow().isoformat(),
+            )
+            self._sessions = [default_session]
+            self._active_session_index = 0
+            return default_session
+
+        def _create_session(self, name: str = "") -> SessionView:
+            """Create a new session with independent A2A binding."""
+            session_id = str(uuid.uuid4())[:8]
+            session_name = name or f"Session {len(self._sessions) + 1}"
+            new_session = SessionView(
+                session_id=session_id,
+                transcript=[],
+                name=session_name,
+                created_at=datetime.utcnow().isoformat(),
+            )
+            self._sessions.append(new_session)
+            return new_session
+
+        def _switch_session(self, session_id: str) -> SessionView | None:
+            """Switch to a session by ID."""
+            for idx, session in enumerate(self._sessions):
+                if session.session_id == session_id:
+                    self._active_session_index = idx
+                    return session
+            return None
+
+        def _close_session(self, session_id: str) -> bool:
+            """Close a session by ID. Returns False if it's the last session."""
+            if len(self._sessions) <= 1:
+                return False
+            for idx, session in enumerate(self._sessions):
+                if session.session_id == session_id:
+                    self._sessions.pop(idx)
+                    # Adjust active index if needed
+                    if self._active_session_index >= len(self._sessions):
+                        self._active_session_index = len(self._sessions) - 1
+                    return True
+            return False
+
+        def _rename_session(self, session_id: str, new_name: str) -> bool:
+            """Rename a session by ID."""
+            for session in self._sessions:
+                if session.session_id == session_id:
+                    session.name = new_name
+                    return True
+            return False
+
+        def _list_sessions(self) -> list[SessionView]:
+            """Get all sessions."""
+            return self._sessions
 
         def compose(self) -> Any:
             yield _Header(show_clock=True)
@@ -149,12 +228,28 @@ if _TEXTUAL_AVAILABLE:
             help_panel.toggle(context_name)
 
         def action_cycle_preset(self) -> None:
-            self._persona_state.cycle_preset(self._session.session_id)
+            session = self._get_active_session()
+            self._persona_state.cycle_preset(session.session_id)
+            self._refresh_persona_bar()
+
+        def action_new_session(self) -> None:
+            """Create a new session (Ctrl+N)."""
+            new_session = self._create_session()
+            self._active_session_index = len(self._sessions) - 1
+            self._refresh_persona_bar()
+
+        def action_close_session(self) -> None:
+            """Close the current session (Ctrl+W)."""
+            session = self._get_active_session()
+            if not self._close_session(session.session_id):
+                # Cannot close the last session
+                return
             self._refresh_persona_bar()
 
         def _refresh_persona_bar(self) -> None:
-            persona = self._persona_state.active_persona(self._session.session_id)
-            preset = self._persona_state.current_preset(self._session.session_id)
+            session = self._get_active_session()
+            persona = self._persona_state.active_persona(session.session_id)
+            preset = self._persona_state.current_preset(session.session_id)
             scope_count = len(persona.scoped_projects) + len(persona.scoped_plans)
             scope_text = f"{scope_count} scope refs"
             bar = self.query_one("#persona-bar", PersonaBar)
@@ -173,9 +268,10 @@ if _TEXTUAL_AVAILABLE:
             if not text:
                 return
 
+            session = self._get_active_session()
             mode_router = InputModeRouter(
                 command_handler=lambda raw: self._command_router.handle(
-                    raw, session_id=self._session.session_id
+                    raw, session_id=session.session_id
                 ),
                 shell_confirm=lambda _cmd: (
                     os.environ.get("CLEVERAGENTS_ALLOW_DANGEROUS_SHELL", "").strip()