feat: add /model command for changing models inside TUI/CLI (#162)

* rebase main

* fix: apply pr comments

* fix: fix critical issue

* fix: ordering /model in cli mode

* feat: refactor /model command handling and add Rich CLI support

---------

Co-authored-by: X-iZhang <zacharyzhang2022@gmail.com>

EvoScientist/EvoScientist.py

@@ -86,6 +86,21 @@ def _ensure_chat_model():
     return _chat_model
 
 
+def set_chat_model(model: str, provider: str | None = None):
+    """Replace the cached chat model with a new one.
+
+    Called by ``/model`` to switch the LLM mid-session.
+    Returns the new chat model instance.
+    """
+    global _chat_model, _EvoScientist_agent
+    from .llm import get_chat_model
+
+    _chat_model = get_chat_model(model=model, provider=provider)
+    # Invalidate the cached default agent so it gets rebuilt with the new model.
+    _EvoScientist_agent = None
+    return _chat_model
+
+
 # =============================================================================
 # MCP caching
 # =============================================================================

EvoScientist/cli/interactive.py

@@ -162,6 +162,7 @@ _SLASH_COMMANDS = [
     ("/mcp", "Manage MCP servers"),
     ("/channel", "Configure messaging channels"),
     ("/compact", "Compact conversation to free context"),
+    ("/model", "Switch model (--save to persist)"),
     ("/exit", "Quit EvoScientist"),
 ]
 
@@ -671,6 +672,7 @@ def cmd_interactive(
 
     async def _async_main_loop():
         """Async main loop with prompt_async and channel queue checking."""
+        nonlocal model
         async with get_checkpointer() as checkpointer:
             # Handle --thread-id resume
             if thread_id:
@@ -1077,6 +1079,37 @@ def cmd_interactive(
                             )
                             continue
 
+                        if user_input.lower().startswith("/model"):
+                            from ..commands.base import CommandContext
+                            from ..commands.manager import manager as cmd_manager
+                            from ..EvoScientist import _ensure_config
+                            from .rich_command_ui import RichCLICommandUI
+
+                            ctx = CommandContext(
+                                agent=state["agent"],
+                                thread_id=state["thread_id"],
+                                ui=RichCLICommandUI(console),
+                                workspace_dir=state["workspace_dir"],
+                                checkpointer=checkpointer,
+                            )
+                            await cmd_manager.execute(user_input, ctx)
+
+                            # Sync agent back if command replaced it (e.g. /model)
+                            if ctx.agent is not state["agent"]:
+                                state["agent"] = ctx.agent
+                                cfg = _ensure_config()
+                                model = cfg.model
+                                state["status_base_snapshot"] = (
+                                    make_empty_status_snapshot(model)
+                                )
+                                await _refresh_status_snapshot(
+                                    reset_streaming_text=True,
+                                )
+                                if _channels_is_running():
+                                    _ch_mod._cli_agent = state["agent"]
+                                    _ch_mod._cli_thread_id = state["thread_id"]
+                            continue
+
                         # Resolve @file mentions — inject file contents inline
                         _, message_to_send, file_warnings = resolve_file_mentions(
                             user_input, state["workspace_dir"]

EvoScientist/cli/rich_command_ui.py

@@ -0,0 +1,126 @@
+"""CommandUI Protocol adapter for the Rich CLI surface.
+
+Methods not exercised by the currently-migrated commands raise
+``NotImplementedError`` rather than silently returning ``None``, so
+future callers fail loudly instead of pretending the command ran.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from rich.console import Console
+from rich.table import Table
+
+from ..commands.base import CommandUI
+
+
+class RichCLICommandUI(CommandUI):
+    """CommandUI implementation that prints to a Rich ``Console``."""
+
+    def __init__(self, console: Console) -> None:
+        self.console = console
+
+    # ── Core I/O ─────────────────────────────────────────────
+
+    @property
+    def supports_interactive(self) -> bool:
+        # Rich CLI has no picker widget, but wait_for_* fall back to
+        # printing a table and returning None (see wait_for_model_pick).
+        return True
+
+    def append_system(self, text: str, style: str = "dim") -> None:
+        self.console.print(text, style=style)
+
+    def mount_renderable(self, renderable: Any) -> None:
+        self.console.print(renderable)
+
+    async def flush(self) -> None:
+        # Rich console flushes synchronously; nothing to await.
+        return
+
+    # ── /model interactive picker fallback ──────────────────
+
+    async def wait_for_model_pick(
+        self,
+        entries: list[tuple[str, str, str]],
+        current_model: str | None,
+        current_provider: str | None,
+    ) -> tuple[str, str] | None:
+        """Print the model table and return ``None``; user re-runs with
+        ``/model <name>`` since the CLI has no interactive picker."""
+        table = Table(
+            title="Available Models",
+            show_header=True,
+            header_style="bold cyan",
+        )
+        table.add_column("Name", style="bold")
+        table.add_column("Provider", style="dim")
+        for name, _mid, prov in entries:
+            marker = " *" if name == current_model and prov == current_provider else ""
+            table.add_row(f"{name}{marker}", prov)
+        self.console.print(table)
+        self.console.print(
+            "[dim]Usage: /model <name> [provider] [--save]  — "
+            "provider is optional, auto-detected from model name[/dim]"
+        )
+        return None
+
+    def update_status_after_model_change(
+        self, new_model: str, new_provider: str | None = None
+    ) -> None:
+        """No-op; the CLI REPL refreshes status itself after detecting an
+        ``ctx.agent`` change post-``cmd_manager.execute``."""
+        return
+
+    # ── Not yet migrated ────────────────────────────────────
+
+    async def wait_for_thread_pick(
+        self, threads: list[dict], current_thread: str, title: str
+    ) -> str | None:
+        raise NotImplementedError(
+            "RichCLICommandUI.wait_for_thread_pick — implement when "
+            "migrating /threads / /resume"
+        )
+
+    async def wait_for_skill_browse(
+        self, index: list[dict], installed_names: set[str], pre_filter_tag: str
+    ) -> list[str] | None:
+        raise NotImplementedError(
+            "RichCLICommandUI.wait_for_skill_browse — implement when "
+            "migrating /skills / /evoskills"
+        )
+
+    async def wait_for_mcp_browse(
+        self, servers: list, installed_names: set[str], pre_filter_tag: str
+    ) -> list | None:
+        raise NotImplementedError(
+            "RichCLICommandUI.wait_for_mcp_browse — implement when migrating /mcp"
+        )
+
+    def clear_chat(self) -> None:
+        raise NotImplementedError(
+            "RichCLICommandUI.clear_chat — implement when migrating /clear"
+        )
+
+    def request_quit(self) -> None:
+        raise NotImplementedError(
+            "RichCLICommandUI.request_quit — implement when migrating /exit"
+        )
+
+    def force_quit(self) -> None:
+        raise NotImplementedError(
+            "RichCLICommandUI.force_quit — implement when migrating /exit"
+        )
+
+    def start_new_session(self) -> None:
+        raise NotImplementedError(
+            "RichCLICommandUI.start_new_session — implement when migrating /new"
+        )
+
+    async def handle_session_resume(
+        self, thread_id: str, workspace_dir: str | None = None
+    ) -> None:
+        raise NotImplementedError(
+            "RichCLICommandUI.handle_session_resume — implement when migrating /resume"
+        )

EvoScientist/cli/tui_interactive.py

@@ -19,6 +19,7 @@ from rich.console import Group
 from rich.text import Text
 
 import EvoScientist.cli.channel as _ch_mod
+from EvoScientist.cli.widgets.thread_selector import ThreadPickerWidget
 
 from ..commands import CommandContext
 from ..commands import manager as cmd_manager
@@ -353,13 +354,16 @@ def run_textual_interactive(
             self._picker_future: asyncio.Future | None = None
             self._browser_future: asyncio.Future | None = None
             self._mcp_browser_future: asyncio.Future | None = None
+            self._model_picker_future: asyncio.Future | None = None
             self._history_suggester = HistorySuggester(DATA_DIR / "history")
             self._history_index: int = -1  # -1 = not browsing history
             self._history_saved_input: str = ""  # saved current input before browsing
             self._background_tasks: set[asyncio.Task] = set()
             self._quit_pending: bool = False
+            self._current_model: str | None = model
+            self._current_provider: str | None = provider
             self._status_started_at = datetime.now()
-            self._status_base_snapshot = make_empty_status_snapshot(model)
+            self._status_base_snapshot = make_empty_status_snapshot(self._current_model)
             self._status_snapshot = self._status_base_snapshot
             self._status_streaming_text = ""
             self._status_last_input_tokens: int | None = None
@@ -430,6 +434,26 @@ def run_textual_interactive(
 
             return await self._wait_for_mcp_browse(browser)
 
+        async def wait_for_model_pick(
+            self,
+            entries: list[tuple[str, str, str]],
+            current_model: str | None,
+            current_provider: str | None,
+        ) -> tuple[str, str] | None:
+            from .widgets.model_picker import ModelPickerWidget
+
+            container = self.query_one("#chat", VerticalScroll)
+            picker = ModelPickerWidget(
+                entries,
+                current_model=current_model,
+                current_provider=current_provider,
+            )
+            await container.mount(picker)
+            self._schedule_scroll_to_bottom(container, delays=())
+            picker.focus()
+
+            return await self._wait_for_model_pick(picker)
+
         def clear_chat(self) -> None:
             container = self.query_one("#chat", VerticalScroll)
             welcome = self.query_one("#welcome", Static)
@@ -452,7 +476,7 @@ def run_textual_interactive(
                 checkpointer=self._checkpointer,
             )
             self._status_started_at = datetime.now()
-            self._status_base_snapshot = make_empty_status_snapshot(model)
+            self._status_base_snapshot = make_empty_status_snapshot(self._current_model)
             self._status_snapshot = self._status_base_snapshot
             self._status_streaming_text = ""
             self._status_last_input_tokens = None
@@ -478,7 +502,7 @@ def run_textual_interactive(
                 checkpointer=self._checkpointer,
             )
             self._status_started_at = datetime.now()
-            self._status_base_snapshot = make_empty_status_snapshot(model)
+            self._status_base_snapshot = make_empty_status_snapshot(self._current_model)
             self._status_snapshot = self._status_base_snapshot
             self._status_streaming_text = ""
             self._status_last_input_tokens = None
@@ -725,7 +749,9 @@ def run_textual_interactive(
                 return {"answers": result.get("answers", []), "status": "answered"}
             return {"status": "cancelled"}
 
-        async def _wait_for_thread_pick(self, picker_widget) -> str | None:
+        async def _wait_for_thread_pick(
+            self, picker_widget: ThreadPickerWidget
+        ) -> str | None:
             """Wait for user to pick a thread from ThreadPickerWidget.
 
             Returns the selected thread_id, or ``None`` on cancel/timeout.
@@ -808,6 +834,34 @@ def run_textual_interactive(
             if self._mcp_browser_future and not self._mcp_browser_future.done():
                 self._mcp_browser_future.set_result(None)
 
+        async def _wait_for_model_pick(self, picker_widget) -> tuple[str, str] | None:
+            """Wait for user to pick a model from ModelPickerWidget.
+
+            Returns ``(name, provider)`` or ``None`` on cancel/timeout.
+            """
+            self._model_picker_future = asyncio.get_event_loop().create_future()
+            try:
+                return await asyncio.wait_for(self._model_picker_future, timeout=120)
+            except (TimeoutError, asyncio.CancelledError):
+                return None
+            finally:
+                self._model_picker_future = None
+                try:
+                    picker_widget.remove()
+                except Exception:
+                    _channel_logger.debug("model picker cleanup failed", exc_info=True)
+                self.query_one("#prompt", ChatTextArea).focus()
+
+        def on_model_picker_widget_picked(self, event) -> None:  # type: ignore[override]
+            """Handle ModelPickerWidget.Picked message."""
+            if self._model_picker_future and not self._model_picker_future.done():
+                self._model_picker_future.set_result((event.name, event.provider))
+
+        def on_model_picker_widget_cancelled(self, event) -> None:  # type: ignore[override]
+            """Handle ModelPickerWidget.Cancelled message."""
+            if self._model_picker_future and not self._model_picker_future.done():
+                self._model_picker_future.set_result(None)
+
         # ── Streaming core ─────────────────────────────────────
 
         async def _stream_with_widgets(
@@ -901,7 +955,7 @@ def run_textual_interactive(
                     lambda: container.scroll_end(animate=False),
                 )
 
-            metadata = build_metadata(self._workspace_dir, model)
+            metadata = build_metadata(self._workspace_dir, self._current_model)
             response = ""
 
             async def _remove_w(w: Static | None) -> None:
@@ -1832,11 +1886,12 @@ def run_textual_interactive(
                     # Force-resolve the future
                     self._ask_user_future.set_result({"type": "cancelled"})
                 return
-            # Delegate to ApprovalWidget, ThreadPickerWidget, or SkillBrowserWidget if focused
+            # Delegate to focused interactive widget
             focused = self.focused
             if focused is not None:
                 from .widgets.approval_widget import ApprovalWidget
                 from .widgets.mcp_browser import MCPBrowserWidget
+                from .widgets.model_picker import ModelPickerWidget
                 from .widgets.skill_browser import SkillBrowserWidget
                 from .widgets.thread_selector import ThreadPickerWidget
 
@@ -1852,6 +1907,14 @@ def run_textual_interactive(
                 if isinstance(focused, MCPBrowserWidget):
                     focused.action_cancel()
                     return
+                if isinstance(focused, ModelPickerWidget):
+                    focused.action_cancel()
+                    if (
+                        self._model_picker_future
+                        and not self._model_picker_future.done()
+                    ):
+                        self._model_picker_future.set_result(None)
+                    return
             if self._queued_messages:
                 self._queued_messages.pop()
                 self._render_queue_indicator()
@@ -1865,12 +1928,13 @@ def run_textual_interactive(
                 self._render_completions()
                 return
 
-            # Skip if an ApprovalWidget, AskUserWidget, ThreadPickerWidget, or SkillBrowserWidget has focus
+            # Skip if an interactive picker widget has focus
             focused = self.focused
             if focused is not None:
                 from .widgets.approval_widget import ApprovalWidget
                 from .widgets.ask_user_widget import AskUserWidget
                 from .widgets.mcp_browser import MCPBrowserWidget
+                from .widgets.model_picker import ModelPickerWidget
                 from .widgets.skill_browser import SkillBrowserWidget
                 from .widgets.thread_selector import ThreadPickerWidget
 
@@ -1889,6 +1953,9 @@ def run_textual_interactive(
                 if isinstance(focused, MCPBrowserWidget):
                     focused.action_move_up()
                     return
+                if isinstance(focused, ModelPickerWidget):
+                    focused.action_move_up()
+                    return
             if self._queued_messages:
                 last = self._queued_messages.pop()
                 prompt = self.query_one("#prompt", ChatTextArea)
@@ -1924,6 +1991,7 @@ def run_textual_interactive(
                 from .widgets.approval_widget import ApprovalWidget
                 from .widgets.ask_user_widget import AskUserWidget
                 from .widgets.mcp_browser import MCPBrowserWidget
+                from .widgets.model_picker import ModelPickerWidget
                 from .widgets.skill_browser import SkillBrowserWidget
                 from .widgets.thread_selector import ThreadPickerWidget
 
@@ -1942,6 +2010,9 @@ def run_textual_interactive(
                 if isinstance(focused, MCPBrowserWidget):
                     focused.action_move_down()
                     return
+                if isinstance(focused, ModelPickerWidget):
+                    focused.action_move_down()
+                    return
 
             # History browsing (down key)
             if self._history_index >= 0:
@@ -2076,6 +2147,12 @@ def run_textual_interactive(
 
             try:
                 if await cmd_manager.execute(command, ctx):
+                    # Sync agent back if command replaced it (e.g. /model)
+                    if ctx.agent is not self._agent:
+                        self._agent = ctx.agent
+                        if _channels_is_running():
+                            _ch_mod._cli_agent = self._agent
+                            _ch_mod._cli_thread_id = self._conversation_tid
                     # Do NOT invalidate the usage baseline after /compact.
                     # build_session_status_snapshot() only counts raw checkpoint
                     # messages (~46 tokens) and misses system prompt + tool
@@ -2247,25 +2324,25 @@ def run_textual_interactive(
                     self._status_base_snapshot = apply_user_text_to_snapshot(
                         make_usage_status_snapshot(
                             self._status_last_input_tokens,
-                            model_name=model,
+                            model_name=self._current_model,
                         ),
                         pending,
                     )
                 else:
                     self._status_base_snapshot = await build_session_status_snapshot(
                         self._conversation_tid,
-                        model_name=model,
+                        model_name=self._current_model,
                         pending_user_text=pending,
                     )
             elif self._status_last_input_tokens is not None:
                 self._status_base_snapshot = make_usage_status_snapshot(
                     self._status_last_input_tokens,
-                    model_name=model,
+                    model_name=self._current_model,
                 )
             else:
                 self._status_base_snapshot = await build_session_status_snapshot(
                     self._conversation_tid,
-                    model_name=model,
+                    model_name=self._current_model,
                 )
             if reset_streaming_text:
                 self._status_streaming_text = ""
@@ -2278,7 +2355,7 @@ def run_textual_interactive(
             self._status_last_input_tokens = input_tokens
             self._status_base_snapshot = make_usage_status_snapshot(
                 input_tokens,
-                model_name=model,
+                model_name=self._current_model,
             )
             self._rebuild_status_snapshot()
 
@@ -2293,10 +2370,21 @@ def run_textual_interactive(
             self._status_last_input_tokens = tokens_after
             self._status_base_snapshot = make_usage_status_snapshot(
                 tokens_after,
-                model_name=model,
+                model_name=self._current_model,
             )
             self._rebuild_status_snapshot()
 
+        def update_status_after_model_change(
+            self, new_model: str, new_provider: str | None = None
+        ) -> None:
+            """Update the status bar and welcome banner after /model switches the LLM."""
+            self._current_model = new_model
+            if new_provider is not None:
+                self._current_provider = new_provider
+            self._status_base_snapshot = make_empty_status_snapshot(new_model)
+            self._rebuild_status_snapshot()
+            self._render_welcome()
+
         def _set_status_streaming_text(self, text: str | None) -> None:
             """Update in-flight assistant text shown in the context bar."""
             new_text = text or ""
@@ -2342,8 +2430,8 @@ def run_textual_interactive(
                     thread_id=self._conversation_tid,
                     workspace_dir=self._workspace_dir,
                     mode=mode,
-                    model=model,
-                    provider=provider,
+                    model=self._current_model,
+                    provider=self._current_provider,
                     ui_backend="tui",
                     channels=channels_info,
                 )

EvoScientist/cli/widgets/model_picker.py

@@ -0,0 +1,294 @@
+"""Inline model picker widget for /model command in TUI.
+
+Keyboard-driven widget mounted directly into the chat container.
+Models are grouped by provider with a search/filter input.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any, ClassVar
+
+from rich.text import Text
+from textual.binding import Binding, BindingType
+from textual.containers import Container
+from textual.message import Message
+from textual.widget import Widget
+from textual.widgets import Static
+
+if TYPE_CHECKING:
+    from textual import events
+    from textual.app import ComposeResult
+
+
+def _build_items(
+    entries: list[tuple[str, str, str]],
+    current_model: str | None = None,
+    current_provider: str | None = None,
+    filter_text: str = "",
+) -> list[dict]:
+    """Build the flat item list rendered by ModelPickerWidget.
+
+    Returns a list of::
+
+        {"type": "header", "label": str}
+        {"type": "model",  "name": str, "model_id": str, "provider": str, "current": bool}
+    """
+    # Apply filter
+    if filter_text:
+        ft = filter_text.lower()
+        entries = [
+            (n, mid, p) for n, mid, p in entries if ft in n.lower() or ft in p.lower()
+        ]
+
+    # Group by provider preserving order
+    groups: dict[str, list[tuple[str, str, str]]] = {}
+    for name, model_id, provider in entries:
+        if provider not in groups:
+            groups[provider] = []
+        groups[provider].append((name, model_id, provider))
+
+    items: list[dict] = []
+    for provider, models in groups.items():
+        items.append({"type": "header", "label": provider})
+        for name, model_id, prov in models:
+            is_current = name == current_model and prov == current_provider
+            items.append(
+                {
+                    "type": "model",
+                    "name": name,
+                    "model_id": model_id,
+                    "provider": prov,
+                    "current": is_current,
+                }
+            )
+    return items
+
+
+class ModelPickerWidget(Widget):
+    """Inline model picker -- mounts in chat, keyboard-driven.
+
+    Posts ``Picked(name, provider)`` on Enter, ``Cancelled()`` on Esc.
+    Type to filter models.
+    """
+
+    can_focus = True
+    can_focus_children = False
+
+    DEFAULT_CSS = """
+    ModelPickerWidget {
+        height: auto;
+        max-height: 30;
+        margin: 1 0;
+        padding: 0 1;
+        background: $surface;
+        border: solid $primary;
+    }
+    ModelPickerWidget .picker-title {
+        height: 1;
+        text-style: bold;
+        color: $primary;
+    }
+    ModelPickerWidget .picker-filter {
+        height: 1;
+        padding: 0 1;
+        color: $text;
+    }
+    ModelPickerWidget .picker-rows {
+        height: auto;
+        max-height: 22;
+        overflow-y: auto;
+    }
+    ModelPickerWidget .picker-header {
+        height: 1;
+        padding: 0 1;
+        margin-top: 1;
+    }
+    ModelPickerWidget .picker-row {
+        height: 1;
+        padding: 0 1;
+    }
+    ModelPickerWidget .picker-row-selected {
+        background: $primary;
+        text-style: bold;
+    }
+    ModelPickerWidget .picker-help {
+        height: 1;
+        color: $text-muted;
+        text-style: italic;
+    }
+    """
+
+    BINDINGS: ClassVar[list[BindingType]] = [
+        Binding("up", "move_up", "Up", show=False),
+        Binding("down", "move_down", "Down", show=False),
+        Binding("enter", "select", "Select", show=False),
+        Binding("escape", "cancel", "Cancel", show=False),
+        Binding("backspace", "backspace", "Backspace", show=False),
+    ]
+
+    class Picked(Message):
+        def __init__(self, name: str, provider: str) -> None:
+            super().__init__()
+            self.name = name
+            self.provider = provider
+
+    class Cancelled(Message):
+        """Posted when user cancels selection."""
+
+    def __init__(
+        self,
+        entries: list[tuple[str, str, str]],
+        *,
+        current_model: str | None = None,
+        current_provider: str | None = None,
+        title: str = ">>> Select model <<<",
+        **kwargs: Any,
+    ) -> None:
+        super().__init__(**kwargs)
+        self._entries = entries
+        self._current_model = current_model
+        self._current_provider = current_provider
+        self._title = title
+        self._filter_text = ""
+        self._items = _build_items(
+            entries,
+            current_model=current_model,
+            current_provider=current_provider,
+        )
+        self._selected = self._first_model_index()
+        self._row_widgets: list[Static] = []
+        self._filter_widget: Static | None = None
+
+    def _first_model_index(self) -> int:
+        for i, item in enumerate(self._items):
+            if item["type"] == "model":
+                return i
+        return 0
+
+    def _move(self, direction: int) -> None:
+        if not self._items:
+            return
+        i = (self._selected + direction) % len(self._items)
+        steps = 0
+        while self._items[i]["type"] != "model" and steps < len(self._items):
+            i = (i + direction) % len(self._items)
+            steps += 1
+        if self._items[i]["type"] == "model":
+            self._selected = i
+            self._update_rows()
+
+    def _rebuild(self) -> None:
+        """Rebuild items from filter and re-render."""
+        self._items = _build_items(
+            self._entries,
+            current_model=self._current_model,
+            current_provider=self._current_provider,
+            filter_text=self._filter_text,
+        )
+        self._selected = self._first_model_index()
+        # Re-mount rows
+        rows_container = self.query_one(".picker-rows", Container)
+        for w in list(rows_container.children):
+            w.remove()
+        self._row_widgets.clear()
+        for item in self._items:
+            css = "picker-header" if item["type"] == "header" else "picker-row"
+            widget = Static("", classes=css)
+            self._row_widgets.append(widget)
+            rows_container.mount(widget)
+        self._update_rows()
+        self._update_filter()
+
+    def compose(self) -> ComposeResult:
+        yield Static(self._title, classes="picker-title")
+        self._filter_widget = Static("", classes="picker-filter")
+        yield self._filter_widget
+        with Container(classes="picker-rows"):
+            for item in self._items:
+                css = "picker-header" if item["type"] == "header" else "picker-row"
+                widget = Static("", classes=css)
+                self._row_widgets.append(widget)
+                yield widget
+        yield Static(
+            "\u2191/\u2193 navigate \u00b7 Enter select \u00b7 Type to filter \u00b7 Esc cancel",
+            classes="picker-help",
+        )
+
+    def on_mount(self) -> None:
+        self._update_rows()
+        self._update_filter()
+        self.call_later(self.focus)
+
+    def _update_filter(self) -> None:
+        if self._filter_widget is not None:
+            if self._filter_text:
+                t = Text()
+                t.append("  Filter: ", style="dim")
+                t.append(self._filter_text, style="bold")
+                t.append("\u2588", style="blink")
+                self._filter_widget.update(t)
+            else:
+                self._filter_widget.update(
+                    Text("  Type to filter...", style="dim italic")
+                )
+
+    def _update_rows(self) -> None:
+        for i, (item, widget) in enumerate(
+            zip(self._items, self._row_widgets, strict=False)
+        ):
+            widget.remove_class("picker-row-selected")
+            if item["type"] == "header":
+                t = Text()
+                t.append("\u2500\u2500 ", style="bold cyan")
+                t.append(item["label"], style="bold cyan")
+                widget.update(t)
+            else:
+                is_selected = i == self._selected
+                t = Text()
+                cursor = "\u25b8 " if is_selected else "  "
+                t.append(cursor, style="bold cyan" if is_selected else "dim")
+                t.append(item["name"], style="bold" if is_selected else "")
+                if item["current"]:
+                    t.append(" *", style="bold green")
+                t.append(f"  ({item['provider']})", style="dim italic")
+                widget.update(t)
+                if is_selected:
+                    widget.add_class("picker-row-selected")
+                    widget.scroll_visible()
+
+    def on_key(self, event: events.Key) -> None:
+        # Let bindings handle special keys
+        if event.key in ("up", "down", "enter", "escape", "backspace"):
+            return
+        # Printable characters -> filter
+        if event.character and event.character.isprintable():
+            self._filter_text += event.character
+            self._rebuild()
+            event.prevent_default()
+
+    def action_backspace(self) -> None:
+        if self._filter_text:
+            self._filter_text = self._filter_text[:-1]
+            self._rebuild()
+
+    def action_move_up(self) -> None:
+        self._move(-1)
+
+    def action_move_down(self) -> None:
+        self._move(1)
+
+    def action_select(self) -> None:
+        if not self._items or self._selected >= len(self._items):
+            self.post_message(self.Cancelled())
+            return
+        item = self._items[self._selected]
+        if item["type"] == "model":
+            self.post_message(self.Picked(item["name"], item["provider"]))
+        else:
+            self.post_message(self.Cancelled())
+
+    def action_cancel(self) -> None:
+        self.post_message(self.Cancelled())
+
+    def on_blur(self, event: events.Blur) -> None:
+        self.call_after_refresh(self.focus)

EvoScientist/commands/base.py

@@ -35,6 +35,12 @@ class CommandUI(Protocol):
     async def wait_for_mcp_browse(
         self, servers: list, installed_names: set[str], pre_filter_tag: str
     ) -> list | None: ...
+    async def wait_for_model_pick(
+        self,
+        entries: list[tuple[str, str, str]],
+        current_model: str | None,
+        current_provider: str | None,
+    ) -> tuple[str, str] | None: ...
     def clear_chat(self) -> None: ...
     def request_quit(self) -> None: ...
     def force_quit(self) -> None: ...

EvoScientist/commands/implementation/__init__.py

@@ -1,5 +1,5 @@
 from __future__ import annotations
 
-from . import channel, general, mcp, session, skills
+from . import channel, general, mcp, model, session, skills
 
-__all__ = ["channel", "general", "mcp", "session", "skills"]
+__all__ = ["channel", "general", "mcp", "model", "session", "skills"]

EvoScientist/commands/implementation/model.py

@@ -0,0 +1,173 @@
+from __future__ import annotations
+
+from typing import ClassVar
+
+from ..base import Argument, Command, CommandContext
+from ..manager import manager
+
+
+def extract_model_and_provider(args: list[str]) -> tuple[str, str]:
+    """Parse model name and provider from argument list.
+
+    Args:
+        args: Non-empty argument list (model_name [provider]).
+
+    Returns:
+        ``(model_name, provider)`` tuple.
+
+    Raises:
+        ValueError: If the model is not in the registry.
+    """
+    from ...llm.models import MODELS
+
+    model_name = args[0]
+    provider_override = args[1] if len(args) > 1 else None
+
+    if model_name not in MODELS:
+        raise ValueError(f"Unknown model '{model_name}'")
+
+    if provider_override:
+        provider = provider_override
+    else:
+        _, provider = MODELS[model_name]
+
+    return model_name, provider
+
+
+class ModelCommand(Command):
+    """Switch the LLM model for the current session."""
+
+    name = "/model"
+    description = "Switch model (--save to persist)"
+    # ``--save`` is parsed manually in ``execute`` via ``"--save" in args``;
+    # ``type=bool`` below is declarative metadata, not enforced by the manager.
+    arguments: ClassVar[list[Argument]] = [
+        Argument(
+            name="model_name",
+            type=str,
+            description="Model short name (e.g. claude-sonnet-4-6). Opens picker if omitted.",
+            required=False,
+        ),
+        Argument(
+            name="--save",
+            type=bool,
+            description="Save the choice to config file",
+            required=False,
+        ),
+    ]
+
+    async def execute(self, ctx: CommandContext, args: list[str]) -> None:
+        from ...EvoScientist import _ensure_config
+        from ...llm.models import list_models_by_provider
+
+        cfg = _ensure_config()
+        current_model = cfg.model
+        current_provider = cfg.provider
+
+        # Parse --save flag
+        save = "--save" in args
+        args = [a for a in args if a != "--save"]
+
+        if args:
+            try:
+                model_name, provider = extract_model_and_provider(args)
+            except ValueError:
+                ctx.ui.append_system(
+                    f"Unknown model '{args[0]}'. Use /model to browse available models.",
+                    style="red",
+                )
+                return
+
+            await self._apply_model(ctx, model_name, provider, save=save)
+            return
+
+        # Interactive picker
+        if not ctx.ui.supports_interactive:
+            ctx.ui.append_system(
+                "Usage: /model <name> [provider] [--save]",
+                style="yellow",
+            )
+            return
+
+        entries = list_models_by_provider()
+        result = await ctx.ui.wait_for_model_pick(
+            entries,
+            current_model=current_model,
+            current_provider=current_provider,
+        )
+        if result is None:
+            return
+
+        name, provider = result
+        await self._apply_model(ctx, name, provider, save=save)
+
+    async def _apply_model(
+        self,
+        ctx: CommandContext,
+        model_name: str,
+        provider: str,
+        *,
+        save: bool = False,
+    ) -> None:
+        import copy
+
+        from ...cli.agent import _load_agent
+        from ...EvoScientist import _ensure_config, set_chat_model
+
+        cfg = _ensure_config()
+
+        # Build a temporary config to verify the agent can be created
+        # before mutating any global state.
+        temp_cfg = copy.copy(cfg)
+        temp_cfg.model = model_name
+        temp_cfg.provider = provider
+
+        try:
+            new_agent = _load_agent(
+                workspace_dir=ctx.workspace_dir,
+                checkpointer=ctx.checkpointer,
+                config=temp_cfg,
+            )
+        except Exception as e:
+            ctx.ui.append_system(f"Failed to switch model: {e}", style="red")
+            return
+
+        # Agent built successfully — now commit the change globally.
+        try:
+            set_chat_model(model_name, provider=provider)
+        except Exception as e:
+            ctx.ui.append_system(f"Failed to switch model: {e}", style="red")
+            return
+
+        cfg.model = model_name
+        cfg.provider = provider
+        ctx.agent = new_agent
+
+        # Persist to config file if --save was given
+        if save:
+            from ...config.settings import set_config_value
+
+            set_config_value("model", model_name)
+            set_config_value("provider", provider)
+
+        # Propagate to channel module if channels are running
+        try:
+            import EvoScientist.cli.channel as _ch_mod
+
+            if getattr(_ch_mod, "_cli_agent", None) is not None:
+                _ch_mod._cli_agent = new_agent
+        except Exception:
+            pass
+
+        # Update status bar if available
+        update_model_fn = getattr(ctx.ui, "update_status_after_model_change", None)
+        if callable(update_model_fn):
+            update_model_fn(model_name, provider)
+
+        saved_note = " (saved to config)" if save else ""
+        ctx.ui.append_system(
+            f"Switched to {model_name} ({provider}){saved_note}", style="green"
+        )
+
+
+manager.register(ModelCommand())

EvoScientist/llm/models.py

@@ -461,6 +461,22 @@ def list_models() -> list[str]:
     return result
 
 
+def list_models_by_provider() -> list[tuple[str, str, str]]:
+    """List all unique (short_name, model_id, provider) entries.
+
+    Returns:
+        De-duplicated list of model entries preserving registry order.
+    """
+    seen: set[tuple[str, str]] = set()
+    result: list[tuple[str, str, str]] = []
+    for name, model_id, provider in _MODEL_ENTRIES:
+        key = (name, provider)
+        if key not in seen:
+            seen.add(key)
+            result.append((name, model_id, provider))
+    return result
+
+
 def get_model_info(model: str) -> tuple[str, str] | None:
     """Get the (model_id, provider) tuple for a short name.