diff --git a/strix/core/agents.py b/strix/core/agents.py
index e4b26989..7438f09d 100644
--- a/strix/core/agents.py
+++ b/strix/core/agents.py
@@ -55,6 +55,7 @@ class AgentCoordinator:
         self.idle_resume_counts: dict[str, int] = {}
         self.wait_kinds: dict[str, WaitKind] = {}
         self.runtimes: dict[str, AgentRuntime] = {}
+        self._parent_notified: set[str] = set()
         self._lock = asyncio.Lock()
         self._snapshot_path: Path | None = None
         self.is_shutting_down = False
@@ -191,6 +192,7 @@ class AgentCoordinator:
                 self.errors.pop(agent_id, None)
                 self.wait_kinds.pop(agent_id, None)
                 self.runtimes.setdefault(agent_id, AgentRuntime()).user_wake_required = False
+                self._parent_notified.discard(agent_id)
         await self._maybe_snapshot()
 
     async def park_waiting(self, agent_id: str, *, wait_kind: WaitKind) -> None:
@@ -252,12 +254,27 @@ class AgentCoordinator:
                 self.errors[agent_id] = error
             elif status == "running":
                 self.errors.pop(agent_id, None)
+            if status == "running":
+                # Running again means a fresh stint that owes its parent its own notice.
+                self._parent_notified.discard(agent_id)
             runtime = self.runtimes.setdefault(agent_id, AgentRuntime())
             runtime.user_wake_required = status in {"failed", "crashed"}
             runtime.wake.set()
         logger.info("agent.status %s=%s", agent_id, status)
         await self._maybe_snapshot()
 
+    async def claim_parent_notice(self, agent_id: str) -> bool:
+        """Reserve the one notice a child owes its parent when it stops running.
+
+        A completion report and a terminal notice carry the same information, so
+        whichever comes first claims the slot and the other is skipped.
+        """
+        async with self._lock:
+            if agent_id in self._parent_notified:
+                return False
+            self._parent_notified.add(agent_id)
+            return True
+
     async def send(
         self, target_agent_id: str, message: dict[str, Any], *, interrupt: bool = True
     ) -> bool:
diff --git a/strix/core/execution.py b/strix/core/execution.py
index 9822ec82..e833d88e 100644
--- a/strix/core/execution.py
+++ b/strix/core/execution.py
@@ -539,7 +539,7 @@ async def _exhausted_recovery(
     """
     if not interactive:
         await coordinator.set_status(agent_id, "crashed")
-        await _notify_parent_on_terminal(coordinator, agent_id, "crashed")
+        await notify_parent_on_terminal(coordinator, agent_id, "crashed")
         raise MaxTurnsExceeded(
             "Agent exhausted recovery attempts without calling finish_scan or agent_finish."
         )
@@ -622,7 +622,7 @@ async def _run_cycle_parked(
     except Exception as exc:
         logger.exception("error escaped the run cycle for %s; parking as failed", agent_id)
         await coordinator.set_status(agent_id, "failed", error=str(exc) or type(exc).__name__)
-        await _notify_parent_on_terminal(coordinator, agent_id, "failed")
+        await notify_parent_on_terminal(coordinator, agent_id, "failed")
         return None
 
 
@@ -778,7 +778,7 @@ async def _run_cycle(  # noqa: PLR0912, PLR0915
             if isinstance(exc, ProviderRefusalError):
                 logger.warning("agent %s refused by the model provider: %s", agent_id, exc)
                 await coordinator.set_status(agent_id, "failed", error=str(exc))
-                await _notify_parent_on_terminal(coordinator, agent_id, "failed")
+                await notify_parent_on_terminal(coordinator, agent_id, "failed")
                 return None
             if not interactive:
                 raise
@@ -790,7 +790,7 @@ async def _run_cycle(  # noqa: PLR0912, PLR0915
                 status = "crashed"
             logger.exception("agent run failed for %s; parking as %s", agent_id, status)
             await coordinator.set_status(agent_id, status, error=str(exc) or type(exc).__name__)
-            await _notify_parent_on_terminal(coordinator, agent_id, status)
+            await notify_parent_on_terminal(coordinator, agent_id, status)
             return None
         else:
             return cast("RunResultBase | None", stream)
@@ -851,6 +851,11 @@ async def _append_tool_required_message(
 
 
 _TERMINAL_NOTICE = {
+    "completed": (
+        "[Agent completed] {name} ({agent_id}) finished and is no longer running, but it "
+        "sent no completion report. Stop waiting on this child; ask it directly if you "
+        "need its results."
+    ),
     "crashed": (
         "[Agent crash] {name} ({agent_id}) terminated unexpectedly. "
         "Stop waiting on this child unless you want to message it again."
@@ -898,7 +903,7 @@ async def _notify_parent_on_stall(
     )
 
 
-async def _notify_parent_on_terminal(
+async def notify_parent_on_terminal(
     coordinator: AgentCoordinator,
     agent_id: str,
     status: str,
@@ -911,6 +916,8 @@ async def _notify_parent_on_terminal(
         name = coordinator.names.get(agent_id, agent_id)
     if parent is None:
         return
+    if not await coordinator.claim_parent_notice(agent_id):
+        return
     await coordinator.send(
         parent,
         {
@@ -945,6 +952,21 @@ async def _notify_root_on_budget_reserve(coordinator: AgentCoordinator) -> None:
     await coordinator.send(root, _reserve_notice())
 
 
+async def _notify_parent_on_exit(
+    coordinator: AgentCoordinator,
+    agent_id: str,
+) -> None:
+    """Backstop for a child whose loop ended without telling its parent.
+
+    Every terminal state counts, including ``completed``: a child that skips its
+    completion report leaves the parent waiting on a message nobody will send.
+    """
+    status = await _agent_status(coordinator, agent_id)
+    if status is None:
+        return
+    await notify_parent_on_terminal(coordinator, agent_id, status)
+
+
 async def _start_child_runner(
     *,
     parent_ctx: dict[str, Any],
@@ -998,6 +1020,9 @@ async def _start_child_runner(
             logger.info("child %s stopped after reaching the scan budget limit", child_id)
         except SubagentBudgetReservedError:
             logger.info("child %s stopped at the sub-agent budget reserve", child_id)
+        finally:
+            if not coordinator.is_shutting_down:
+                await _notify_parent_on_exit(coordinator, child_id)
 
     task_handle = asyncio.create_task(_child_loop(), name=f"agent-{name}-{child_id}")
     await coordinator.attach_runtime(child_id, task=task_handle)
diff --git a/strix/tools/agents_graph/tools.py b/strix/tools/agents_graph/tools.py
index 28bb9e07..33033cf5 100644
--- a/strix/tools/agents_graph/tools.py
+++ b/strix/tools/agents_graph/tools.py
@@ -13,6 +13,7 @@ from typing import Any, Literal, get_args
 from agents import RunContextWrapper, function_tool
 
 from strix.core.agents import Status, coordinator_from_context
+from strix.core.execution import notify_parent_on_terminal
 from strix.skills import validate_requested_skills
 
 
@@ -558,7 +559,7 @@ async def agent_finish(
         )
 
     parent_notified = False
-    if report_to_parent:
+    if report_to_parent and await coordinator.claim_parent_notice(me):
         async with coordinator._lock:
             agent_name = coordinator.names.get(me, me)
         report = _render_completion_report(
@@ -582,6 +583,11 @@ async def agent_finish(
         )
         parent_notified = True
 
+    await coordinator.set_status(me, "completed")
+    if not parent_notified:
+        # Silence here would leave a parent waiting on a report that is never coming.
+        await notify_parent_on_terminal(coordinator, me, "completed")
+
     logger.info(
         "agent_finish: %s success=%s findings=%d parent_notified=%s",
         me,
@@ -589,7 +595,6 @@ async def agent_finish(
         len(findings or []),
         parent_notified,
     )
-    await coordinator.set_status(me, "completed")
 
     return json.dumps(
         {
diff --git a/tests/test_execution.py b/tests/test_execution.py
index 3d435c0c..8e5b57f6 100644
--- a/tests/test_execution.py
+++ b/tests/test_execution.py
@@ -18,10 +18,11 @@ from openai.types.responses import ResponseOutputMessage, ResponseOutputRefusal
 from strix.core import execution
 from strix.core.agents import AgentCoordinator
 from strix.core.execution import (
-    _notify_parent_on_terminal,
     _notify_root_on_budget_reserve,
+    notify_parent_on_terminal,
 )
 from strix.core.sessions import seed_initial_input
+from strix.tools.agents_graph.tools import agent_finish
 from strix.tools.finish.tool import finish_scan
 
 
@@ -67,6 +68,27 @@ async def _call_finish_scan(
     return parsed
 
 
+async def _call_agent_finish(
+    coordinator: AgentCoordinator,
+    agent_id: str,
+    parent_id: str | None,
+    *,
+    report_to_parent: bool,
+) -> dict[str, Any]:
+    ctx = ToolContext(
+        context={"coordinator": coordinator, "agent_id": agent_id, "parent_id": parent_id},
+        tool_name="agent_finish",
+        tool_call_id="call-1",
+        tool_arguments="{}",
+    )
+    result: str = await agent_finish.on_invoke_tool(
+        ctx,
+        json.dumps({"result_summary": "done", "report_to_parent": report_to_parent}),
+    )
+    parsed: dict[str, Any] = json.loads(result)
+    return parsed
+
+
 @pytest.mark.asyncio
 async def test_reserve_stop_notifies_root_once(monkeypatch: pytest.MonkeyPatch) -> None:
     coordinator = AgentCoordinator()
@@ -466,11 +488,11 @@ async def test_snapshot_round_trip_preserves_budget_pause() -> None:
 
 
 @pytest.mark.asyncio
-@pytest.mark.parametrize("status", ["stopped", "failed", "crashed"])
+@pytest.mark.parametrize("status", ["completed", "stopped", "failed", "crashed"])
 async def test_terminal_child_wakes_parked_parent(tmp_path: Any, status: str) -> None:
-    # Regression for #870: a child reaching a terminal state (e.g. MaxTurnsExceeded
-    # -> "stopped") must wake the parent parked in wait_for_message, so the root can
-    # finalize the scan instead of hanging for a completion report that never arrives.
+    # Regression for #870 and #947: a child reaching any terminal state - including a
+    # plain "completed" - must wake the parent parked in wait_for_agents, so the root
+    # can finalize the scan instead of hanging for a report that never arrives.
     coordinator = AgentCoordinator()
     await coordinator.register("root", "strix", parent_id=None)
     await coordinator.register("child", "SQL Injection", parent_id="root")
@@ -482,13 +504,50 @@ async def test_terminal_child_wakes_parked_parent(tmp_path: Any, status: str) ->
     assert not root_waiter.done()
 
     await coordinator.set_status("child", status, error="Max turns (500) exceeded")
-    await _notify_parent_on_terminal(coordinator, "child", status)
+    await notify_parent_on_terminal(coordinator, "child", status)
 
     await asyncio.wait_for(root_waiter, timeout=1.0)
     assert coordinator.pending_counts.get("root", 0) > 0
     session.close()
 
 
+@pytest.mark.asyncio
+async def test_agent_finish_without_report_still_wakes_parent(tmp_path: Any) -> None:
+    # Regression for #947: a child that completes with report_to_parent=False owes its
+    # parent a terminal notice, otherwise the parent waits out its full timeout.
+    coordinator = AgentCoordinator()
+    await coordinator.register("root", "strix", parent_id=None)
+    await coordinator.register("child", "recon", parent_id="root")
+    session = SQLiteSession("root", tmp_path / "agents.db")
+    await coordinator.attach_runtime("root", session=session)
+
+    root_waiter = asyncio.create_task(coordinator.wait_for_message("root"))
+    await asyncio.sleep(0)
+
+    await _call_agent_finish(coordinator, "child", "root", report_to_parent=False)
+
+    await asyncio.wait_for(root_waiter, timeout=1.0)
+    assert coordinator.statuses["child"] == "completed"
+    assert coordinator.pending_counts.get("root", 0) == 1
+    session.close()
+
+
+@pytest.mark.asyncio
+async def test_agent_finish_report_suppresses_the_terminal_notice(tmp_path: Any) -> None:
+    coordinator = AgentCoordinator()
+    await coordinator.register("root", "strix", parent_id=None)
+    await coordinator.register("child", "recon", parent_id="root")
+    session = SQLiteSession("root", tmp_path / "agents.db")
+    await coordinator.attach_runtime("root", session=session)
+
+    await _call_agent_finish(coordinator, "child", "root", report_to_parent=True)
+    # The exit backstop must not duplicate the report the child already delivered.
+    await execution._notify_parent_on_exit(coordinator, "child")
+
+    assert coordinator.pending_counts.get("root", 0) == 1
+    session.close()
+
+
 @pytest.mark.asyncio
 async def test_notify_parent_on_terminal_ignores_non_terminal_status(tmp_path: Any) -> None:
     coordinator = AgentCoordinator()
@@ -497,7 +556,7 @@ async def test_notify_parent_on_terminal_ignores_non_terminal_status(tmp_path: A
     session = SQLiteSession("root", tmp_path / "agents.db")
     await coordinator.attach_runtime("root", session=session)
 
-    await _notify_parent_on_terminal(coordinator, "child", "waiting")
+    await notify_parent_on_terminal(coordinator, "child", "waiting")
 
     assert coordinator.pending_counts.get("root", 0) == 0
     session.close()
@@ -523,7 +582,7 @@ async def test_terminal_notice_does_not_cancel_parent_stream(tmp_path: Any) -> N
     await coordinator.attach_runtime("root", session=session, interrupt_on_message=True)
     await coordinator.attach_stream("root", stream)
 
-    await _notify_parent_on_terminal(coordinator, "child", "crashed")
+    await notify_parent_on_terminal(coordinator, "child", "crashed")
 
     assert stream.cancelled is False
     assert coordinator.pending_counts.get("root", 0) > 0