fix(sdk): populate RunResult.tools_used and RunResult.messages

``Nanobot.run()`` has always documented ``RunResult.tools_used`` and
``RunResult.messages`` but actually returned ``[]`` for both, so SDK
consumers could never inspect which tools fired or what the final
message list looked like — the only useful field was ``content``.

This threads the data out via a tiny ``_SDKCaptureHook`` that installs
alongside any user-supplied hooks. The capture hook accumulates tool
names across iterations and snapshots the message list on each
``after_iteration`` call; the last snapshot reflects end-of-turn state.

Only the SDK facade is touched: ``AgentLoop.process_direct`` and
``AgentRunner`` signatures are unchanged, so channels / CLI / API paths
are unaffected.

nanobot/nanobot.py

@@ -6,7 +6,7 @@ from dataclasses import dataclass
 from pathlib import Path
 from typing import Any
 
-from nanobot.agent.hook import AgentHook
+from nanobot.agent.hook import AgentHook, AgentHookContext
 from nanobot.agent.loop import AgentLoop
 from nanobot.bus.queue import MessageBus
 
@@ -104,9 +104,10 @@ class Nanobot:
                 Different keys get independent history.
             hooks: Optional lifecycle hooks for this run.
         """
+        capture = _SDKCaptureHook()
         prev = self._loop._extra_hooks
-        if hooks is not None:
-            self._loop._extra_hooks = list(hooks)
+        base_hooks = list(hooks) if hooks is not None else list(prev or [])
+        self._loop._extra_hooks = [capture, *base_hooks]
         try:
             response = await self._loop.process_direct(
                 message, session_key=session_key,
@@ -115,7 +116,30 @@ class Nanobot:
             self._loop._extra_hooks = prev
 
         content = (response.content if response else None) or ""
-        return RunResult(content=content, tools_used=[], messages=[])
+        return RunResult(
+            content=content,
+            tools_used=capture.tools_used,
+            messages=capture.messages,
+        )
+
+
+class _SDKCaptureHook(AgentHook):
+    """Record tool names and the final message list for ``RunResult``.
+
+    The runner mutates ``context.messages`` in place across iterations, so the
+    snapshot is refreshed on every ``after_iteration`` call; the last call
+    reflects the end-of-turn state the SDK caller cares about.
+    """
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.tools_used: list[str] = []
+        self.messages: list[dict[str, Any]] = []
+
+    async def after_iteration(self, context: AgentHookContext) -> None:
+        for call in context.tool_calls:
+            self.tools_used.append(call.name)
+        self.messages = list(context.messages)
 
 
 def _make_provider(config: Any) -> Any:

tests/test_nanobot_facade.py

@@ -163,6 +163,139 @@ async def test_run_custom_session_key(tmp_path):
 
 
 def test_import_from_top_level():
-    from nanobot import Nanobot as N, RunResult as R
-    assert N is Nanobot
-    assert R is RunResult
+    import nanobot
+
+    assert nanobot.Nanobot is Nanobot
+    assert nanobot.RunResult is RunResult
+
+
+# ---------------------------------------------------------------------------
+# RunResult.tools_used / messages — populated from the agent iterations
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+async def test_run_populates_tools_used_across_iterations(tmp_path):
+    """tools_used collects every tool name fired across all iterations, in order."""
+    from nanobot.agent.hook import AgentHookContext
+    from nanobot.bus.events import OutboundMessage
+    from nanobot.providers.base import ToolCallRequest
+
+    config_path = _write_config(tmp_path)
+    bot = Nanobot.from_config(config_path, workspace=tmp_path)
+
+    async def fake_process_direct(message, *, session_key):
+        # Whatever hooks the SDK installed are now on the loop.
+        extras = bot._loop._extra_hooks
+        messages = [{"role": "user", "content": message}]
+        ctx1 = AgentHookContext(iteration=0, messages=messages)
+        ctx1.tool_calls = [
+            ToolCallRequest(id="c1", name="read_file", arguments={}),
+            ToolCallRequest(id="c2", name="glob", arguments={}),
+        ]
+        for h in extras:
+            await h.after_iteration(ctx1)
+        messages.append({"role": "assistant", "content": "ok"})
+        ctx2 = AgentHookContext(iteration=1, messages=messages)
+        ctx2.tool_calls = [ToolCallRequest(id="c3", name="web_fetch", arguments={})]
+        for h in extras:
+            await h.after_iteration(ctx2)
+        return OutboundMessage(channel="cli", chat_id="direct", content="final")
+
+    bot._loop.process_direct = fake_process_direct
+    result = await bot.run("do stuff")
+    assert result.content == "final"
+    assert result.tools_used == ["read_file", "glob", "web_fetch"]
+
+
+@pytest.mark.asyncio
+async def test_run_populates_final_messages(tmp_path):
+    """messages reflects the agent's message list at the last iteration."""
+    from nanobot.agent.hook import AgentHookContext
+    from nanobot.bus.events import OutboundMessage
+
+    config_path = _write_config(tmp_path)
+    bot = Nanobot.from_config(config_path, workspace=tmp_path)
+
+    async def fake_process_direct(message, *, session_key):
+        extras = bot._loop._extra_hooks
+        messages = [
+            {"role": "user", "content": message},
+            {"role": "assistant", "content": "hi there"},
+        ]
+        ctx = AgentHookContext(iteration=0, messages=messages)
+        for h in extras:
+            await h.after_iteration(ctx)
+        return OutboundMessage(channel="cli", chat_id="direct", content="hi there")
+
+    bot._loop.process_direct = fake_process_direct
+    result = await bot.run("hello")
+    assert result.messages == [
+        {"role": "user", "content": "hello"},
+        {"role": "assistant", "content": "hi there"},
+    ]
+
+
+@pytest.mark.asyncio
+async def test_run_no_iterations_leaves_defaults_empty(tmp_path):
+    """If process_direct never triggers after_iteration, tools_used/messages stay []."""
+    from nanobot.bus.events import OutboundMessage
+
+    config_path = _write_config(tmp_path)
+    bot = Nanobot.from_config(config_path, workspace=tmp_path)
+    bot._loop.process_direct = AsyncMock(
+        return_value=OutboundMessage(channel="cli", chat_id="direct", content="noop"),
+    )
+    result = await bot.run("hi")
+    assert result.tools_used == []
+    assert result.messages == []
+
+
+@pytest.mark.asyncio
+async def test_run_user_hooks_still_fire_alongside_capture(tmp_path):
+    """Capture hook must not displace user-provided hooks."""
+    from nanobot.agent.hook import AgentHook, AgentHookContext
+    from nanobot.bus.events import OutboundMessage
+
+    config_path = _write_config(tmp_path)
+    bot = Nanobot.from_config(config_path, workspace=tmp_path)
+
+    seen_iterations: list[int] = []
+
+    class UserHook(AgentHook):
+        async def after_iteration(self, context: AgentHookContext) -> None:
+            seen_iterations.append(context.iteration)
+
+    async def fake_process_direct(message, *, session_key):
+        extras = bot._loop._extra_hooks
+        assert len(extras) == 2, f"expected capture + user hook, got {len(extras)}"
+        ctx = AgentHookContext(iteration=7, messages=[])
+        for h in extras:
+            await h.after_iteration(ctx)
+        return OutboundMessage(channel="cli", chat_id="direct", content="ok")
+
+    bot._loop.process_direct = fake_process_direct
+    await bot.run("x", hooks=[UserHook()])
+    assert seen_iterations == [7]
+
+
+@pytest.mark.asyncio
+async def test_run_restores_extra_hooks_even_on_populated_iterations(tmp_path):
+    """Previously-installed _extra_hooks must be restored regardless of capture state."""
+    from nanobot.agent.hook import AgentHook, AgentHookContext
+    from nanobot.bus.events import OutboundMessage
+
+    config_path = _write_config(tmp_path)
+    bot = Nanobot.from_config(config_path, workspace=tmp_path)
+
+    sentinel_hook = AgentHook()
+    bot._loop._extra_hooks = [sentinel_hook]
+
+    async def fake_process_direct(message, *, session_key):
+        ctx = AgentHookContext(iteration=0, messages=[])
+        for h in bot._loop._extra_hooks:
+            await h.after_iteration(ctx)
+        return OutboundMessage(channel="cli", chat_id="direct", content="done")
+
+    bot._loop.process_direct = fake_process_direct
+    await bot.run("hello")
+    assert bot._loop._extra_hooks == [sentinel_hook]