fix(acp): emit native plan updates for todo

acp_adapter/events.py

@@ -14,6 +14,7 @@ from collections import deque
 from typing import Any, Callable, Deque, Dict
 
 import acp
+from acp.schema import AgentPlanUpdate, PlanEntry
 
 from .tools import (
     build_tool_complete,
@@ -24,6 +25,52 @@ from .tools import (
 logger = logging.getLogger(__name__)
 
 
+def _build_plan_update_from_todo_result(result: Any) -> AgentPlanUpdate | None:
+    """Translate Hermes' todo tool result into ACP's native plan update.
+
+    Zed renders ``sessionUpdate: plan`` as its first-class task/todo panel. The
+    Hermes agent already maintains task state through the ``todo`` tool, so the
+    ACP adapter should expose that state natively instead of only as a generic
+    tool-call transcript block.
+    """
+    if not isinstance(result, str) or not result.strip():
+        return None
+
+    try:
+        data = json.loads(result)
+    except Exception:
+        return None
+
+    if not isinstance(data, dict) or not isinstance(data.get("todos"), list):
+        return None
+
+    status_map = {
+        "pending": "pending",
+        "in_progress": "in_progress",
+        "completed": "completed",
+        # ACP plans only support pending/in_progress/completed. Preserve
+        # cancelled tasks as terminal entries instead of dropping them and
+        # making the client's full-list replacement lose visible context.
+        "cancelled": "completed",
+    }
+    entries: list[PlanEntry] = []
+    for item in data["todos"]:
+        if not isinstance(item, dict):
+            continue
+        content = str(item.get("content") or item.get("id") or "").strip()
+        if not content:
+            continue
+        raw_status = str(item.get("status") or "pending").strip()
+        status = status_map.get(raw_status, "pending")
+        if raw_status == "cancelled":
+            content = f"[cancelled] {content}"
+        entries.append(PlanEntry(content=content, priority="medium", status=status))
+
+    if not entries:
+        return None
+    return AgentPlanUpdate(session_update="plan", entries=entries)
+
+
 def _send_update(
     conn: acp.Client,
     session_id: str,
@@ -175,6 +222,10 @@ def make_step_cb(
                         snapshot=meta.get("snapshot"),
                     )
                     _send_update(conn, session_id, loop, update)
+                    if tool_name == "todo":
+                        plan_update = _build_plan_update_from_todo_result(result)
+                        if plan_update is not None:
+                            _send_update(conn, session_id, loop, plan_update)
                     if not queue:
                         tool_call_ids.pop(tool_name, None)
 

tests/acp/test_events.py

@@ -9,7 +9,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import pytest
 
 import acp
-from acp.schema import ToolCallStart, ToolCallProgress, AgentThoughtChunk, AgentMessageChunk
+from acp.schema import AgentPlanUpdate, ToolCallStart, ToolCallProgress, AgentThoughtChunk, AgentMessageChunk
 
 from acp_adapter.events import (
     _send_update,
@@ -296,6 +296,36 @@ class TestStepCallback:
         }
         mock_send.assert_called_once()
 
+    def test_todo_completion_emits_native_plan_update(self, mock_conn, event_loop_fixture):
+        from collections import deque
+
+        tool_call_ids = {"todo": deque(["tc-todo"])}
+        loop = event_loop_fixture
+        cb = make_step_cb(mock_conn, "session-1", loop, tool_call_ids, {})
+        todo_result = (
+            '{"todos":['
+            '{"id":"inspect","content":"Inspect ACP","status":"completed"},'
+            '{"id":"patch","content":"Patch renderer","status":"in_progress"},'
+            '{"id":"old","content":"Drop stale task","status":"cancelled"}'
+            '],"summary":{"total":3}}'
+        )
+
+        with patch("acp_adapter.events._send_update") as mock_send:
+            cb(1, [{"name": "todo", "result": todo_result}])
+
+        updates = [call.args[3] for call in mock_send.call_args_list]
+        plan_updates = [u for u in updates if getattr(u, "session_update", None) == "plan"]
+        assert len(plan_updates) == 1
+        plan = plan_updates[0]
+        assert isinstance(plan, AgentPlanUpdate)
+        assert [entry.content for entry in plan.entries] == [
+            "Inspect ACP",
+            "Patch renderer",
+            "[cancelled] Drop stale task",
+        ]
+        assert [entry.status for entry in plan.entries] == ["completed", "in_progress", "completed"]
+        assert [entry.priority for entry in plan.entries] == ["medium", "medium", "medium"]
+
 
 # ---------------------------------------------------------------------------
 # Message callback