refactor(agent): extract turn hook assembly

nanobot/agent/loop.py

@@ -21,9 +21,8 @@ from nanobot.agent.autocompact import AutoCompact
 from nanobot.agent.automation_turns import publish_next_deferred_turn
 from nanobot.agent.context import ContextBuilder
 from nanobot.agent.cron_turns import CronTurnCoordinator
-from nanobot.agent.hook import AgentHook, CompositeHook
+from nanobot.agent.hook import AgentHook
 from nanobot.agent.memory import Consolidator
-from nanobot.agent.progress_hook import AgentProgressHook
 from nanobot.agent.runner import _MAX_INJECTIONS_PER_TURN, AgentRunner, AgentRunSpec
 from nanobot.agent.subagent import SubagentManager
 from nanobot.agent.tools.context import RequestContext, bind_request_context, reset_request_context
@@ -31,6 +30,7 @@ from nanobot.agent.tools.file_state import FileStateStore, bind_file_states, res
 from nanobot.agent.tools.message import MessageTool
 from nanobot.agent.tools.registry import ToolRegistry
 from nanobot.agent.tools.self import MyTool
+from nanobot.agent.turn_hooks import AgentTurnHookSpec, build_agent_turn_hook
 from nanobot.bus.events import InboundMessage, OutboundMessage
 from nanobot.bus.outbound_events import (
     RetryWaitEvent,
@@ -753,7 +753,7 @@ class AgentLoop:
         """
         self._sync_subagent_runtime_limits()
 
-        loop_hook = AgentProgressHook(
+        hook = build_agent_turn_hook(AgentTurnHookSpec(
             on_progress=on_progress,
             on_stream=on_stream,
             on_stream_end=on_stream_end,
@@ -765,11 +765,11 @@ class AgentLoop:
             tool_hint_max_length=self.tool_hint_max_length,
             set_tool_context=self._set_tool_context,
             on_iteration=lambda iteration: setattr(self, "_current_iteration", iteration),
-        )
+            registered_hooks=self._extra_hooks,
-        run_hooks = [*self._extra_hooks, *(hooks or [])]
+            turn_hooks=list(hooks or []),
-        hook: AgentHook = loop_hook
+            ephemeral=ephemeral,
-        if run_hooks and (not ephemeral or run_extra_hooks_for_ephemeral):
+            run_extra_hooks_for_ephemeral=run_extra_hooks_for_ephemeral,
-            hook = CompositeHook([loop_hook, *run_hooks])
+        ))
 
         async def _checkpoint(payload: dict[str, Any]) -> None:
             if session is None:

nanobot/agent/turn_hooks.py

@@ -0,0 +1,52 @@
+"""Turn-scoped hook assembly for agent runs."""
+
+from __future__ import annotations
+
+from collections.abc import Awaitable, Callable
+from dataclasses import dataclass, field
+from typing import Any
+
+from nanobot.agent.hook import AgentHook, CompositeHook
+from nanobot.agent.progress_hook import AgentProgressHook
+
+
+@dataclass(slots=True)
+class AgentTurnHookSpec:
+    """Inputs needed to build the hook chain for one agent turn."""
+
+    on_progress: Callable[..., Awaitable[None]] | None = None
+    on_stream: Callable[[str], Awaitable[None]] | None = None
+    on_stream_end: Callable[..., Awaitable[None]] | None = None
+    channel: str = "cli"
+    chat_id: str = "direct"
+    message_id: str | None = None
+    metadata: dict[str, Any] | None = None
+    session_key: str | None = None
+    tool_hint_max_length: int = 40
+    set_tool_context: Callable[..., None] | None = None
+    on_iteration: Callable[[int], None] | None = None
+    registered_hooks: list[AgentHook] = field(default_factory=list)
+    turn_hooks: list[AgentHook] = field(default_factory=list)
+    ephemeral: bool = False
+    run_extra_hooks_for_ephemeral: bool = False
+
+
+def build_agent_turn_hook(spec: AgentTurnHookSpec) -> AgentHook:
+    """Build the hook chain used by ``AgentRunner`` for one turn."""
+    progress_hook = AgentProgressHook(
+        on_progress=spec.on_progress,
+        on_stream=spec.on_stream,
+        on_stream_end=spec.on_stream_end,
+        channel=spec.channel,
+        chat_id=spec.chat_id,
+        message_id=spec.message_id,
+        metadata=spec.metadata,
+        session_key=spec.session_key,
+        tool_hint_max_length=spec.tool_hint_max_length,
+        set_tool_context=spec.set_tool_context,
+        on_iteration=spec.on_iteration,
+    )
+    extra_hooks = [*spec.registered_hooks, *spec.turn_hooks]
+    if extra_hooks and (not spec.ephemeral or spec.run_extra_hooks_for_ephemeral):
+        return CompositeHook([progress_hook, *extra_hooks])
+    return progress_hook

tests/agent/test_turn_hooks.py

@@ -0,0 +1,56 @@
+import pytest
+
+from nanobot.agent.hook import AgentHook, AgentHookContext
+from nanobot.agent.turn_hooks import AgentTurnHookSpec, build_agent_turn_hook
+
+
+class RecordingHook(AgentHook):
+    def __init__(self, events: list[str]) -> None:
+        super().__init__()
+        self._events = events
+
+    async def before_iteration(self, context: AgentHookContext) -> None:
+        self._events.append(f"hook:{context.iteration}")
+
+
+@pytest.mark.asyncio
+async def test_turn_hook_builder_runs_progress_hook_before_extra_hooks() -> None:
+    events: list[str] = []
+
+    hook = build_agent_turn_hook(AgentTurnHookSpec(
+        on_iteration=lambda iteration: events.append(f"progress:{iteration}"),
+        registered_hooks=[RecordingHook(events)],
+    ))
+
+    await hook.before_iteration(AgentHookContext(iteration=2, messages=[]))
+
+    assert events == ["progress:2", "hook:2"]
+
+
+@pytest.mark.asyncio
+async def test_turn_hook_builder_skips_extra_hooks_for_ephemeral_turns_by_default() -> None:
+    events: list[str] = []
+
+    hook = build_agent_turn_hook(AgentTurnHookSpec(
+        registered_hooks=[RecordingHook(events)],
+        ephemeral=True,
+    ))
+
+    await hook.before_iteration(AgentHookContext(iteration=1, messages=[]))
+
+    assert events == []
+
+
+@pytest.mark.asyncio
+async def test_turn_hook_builder_can_include_extra_hooks_for_ephemeral_turns() -> None:
+    events: list[str] = []
+
+    hook = build_agent_turn_hook(AgentTurnHookSpec(
+        registered_hooks=[RecordingHook(events)],
+        ephemeral=True,
+        run_extra_hooks_for_ephemeral=True,
+    ))
+
+    await hook.before_iteration(AgentHookContext(iteration=1, messages=[]))
+
+    assert events == ["hook:1"]