diff --git a/nanobot/utils/llm_runtime.py b/nanobot/utils/llm_runtime.py
index 89fdf7f9..7594126f 100644
--- a/nanobot/utils/llm_runtime.py
+++ b/nanobot/utils/llm_runtime.py
@@ -26,6 +26,7 @@ class LLMRuntime:
     context_window_tokens: int
     model_preset: str | None = None
     snapshot_signature: tuple[object, ...] | None = None
+    runtime_probe: str | None = None
 
     @classmethod
     def capture(
diff --git a/tests/agent/test_runtime_probe.py b/tests/agent/test_runtime_probe.py
new file mode 100644
index 00000000..d7a9483f
--- /dev/null
+++ b/tests/agent/test_runtime_probe.py
@@ -0,0 +1,60 @@
+"""Temporary change-amplification probe for the runtime foundation."""
+
+import asyncio
+from dataclasses import replace
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+
+from nanobot.agent.tools.context import RequestContext, current_request_context, request_context
+from nanobot.agent.tools.spawn import SpawnTool
+from nanobot.providers.base import GenerationSettings, LLMResponse
+
+
+@pytest.mark.asyncio
+async def test_runtime_probe_reaches_all_consumers_without_new_plumbing(loop_factory) -> None:
+    provider = MagicMock()
+    provider.get_default_model.return_value = "test-model"
+    provider.generation = GenerationSettings(temperature=0.1, max_tokens=1024)
+    provider.chat_with_retry = AsyncMock(
+        return_value=LLMResponse(content="ok", tool_calls=[]),
+    )
+    loop = loop_factory(provider=provider, context_window_tokens=32_768)
+    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock()
+    loop._schedule_background = lambda coro: coro.close()
+
+    runtime = replace(loop.llm_runtime(), runtime_probe="session:probe")
+    seen: dict[str, object] = {}
+    original_runner_run = loop.runner.run
+
+    async def observe_runner(spec):
+        seen["runner"] = spec.runtime
+        seen["request_context"] = current_request_context()
+        return await original_runner_run(spec)
+
+    loop.runner.run = observe_runner
+    await loop.process_direct("probe", session_key="sdk:probe", runtime=runtime)
+
+    assert seen["runner"] is runtime
+    request_ctx = seen["request_context"]
+    assert isinstance(request_ctx, RequestContext)
+    assert request_ctx.runtime is runtime
+    assert all(
+        call.kwargs["runtime"] is runtime
+        for call in loop.consolidator.maybe_consolidate_by_tokens.call_args_list
+    )
+
+    async def observe_subagent(*args):
+        seen["subagent"] = args[5]
+
+    loop.subagents._run_subagent = AsyncMock(side_effect=observe_subagent)
+    tool = SpawnTool(loop.subagents)
+    with request_context(request_ctx):
+        result = await tool.execute(task="observe the runtime probe")
+
+    tasks = list(loop.subagents._running_tasks.values())
+    await asyncio.gather(*tasks)
+
+    assert "started" in result
+    assert seen["subagent"] is runtime
+    assert runtime.runtime_probe == "session:probe"