refactor(agent): add turn hook factories

nanobot/agent/hook.py

@@ -2,7 +2,9 @@
 
 from __future__ import annotations
 
+from collections.abc import Awaitable, Callable
 from dataclasses import dataclass, field
+from pathlib import Path
 from typing import Any
 
 from loguru import logger
@@ -44,6 +46,20 @@ class AgentRunHookContext:
     exception: BaseException | None = None
 
 
+@dataclass(slots=True)
+class AgentTurnHookContext:
+    """Turn-local inputs available when constructing per-turn hooks."""
+
+    on_progress: Callable[..., Awaitable[None]] | None = None
+    workspace: Path | None = None
+    channel: str = "cli"
+    chat_id: str = "direct"
+    message_id: str | None = None
+    session_key: str | None = None
+    metadata: dict[str, Any] = field(default_factory=dict)
+    ephemeral: bool = False
+
+
 class AgentHook:
     """Minimal lifecycle surface for shared runner customization."""
 
@@ -95,6 +111,9 @@ class AgentHook:
         return content
 
 
+AgentTurnHookFactory = Callable[[AgentTurnHookContext], AgentHook | None]
+
+
 class CompositeHook(AgentHook):
     """Fan-out hook that delegates to an ordered list of hooks.