diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index 9aee39a5..d2c42eea 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -10,6 +10,7 @@ on:
 env:
   TWINE_PASSWORD: ${{secrets.TWINE_PASSWORD}}
   GITHUB_API_TOKEN: ${{secrets.API_TOKEN}}
+  CODECOV_TOKEN: ${{secrets.CODECOV_TOKEN}}
 
 jobs:
   build:
@@ -60,6 +61,10 @@ jobs:
           PY_TEST_EXTRA_ARGS: --cov-report=xml
 
       - uses: codecov/codecov-action@v3.1.5
+        with:
+          fail_ci_if_error: true
+          verbose: true
+          token: ${{secrets.CODECOV_TOKEN}}
 
       - run: mk pypi-upload-ci
         env:
@@ -72,7 +77,7 @@ jobs:
 
       - run: |
           mk python-release owner=vkottler \
-                            repo=runtimepy version=4.6.1
+                            repo=runtimepy version=5.0.0
         if: |
           matrix.python-version == '3.11'
           && matrix.system == 'ubuntu-latest'
diff --git a/README.md b/README.md
index ce365641..19bae669 100644
--- a/README.md
+++ b/README.md
@@ -2,11 +2,11 @@
     =====================================
     generator=datazen
     version=3.1.4
-    hash=4418deec8fe739bca86f22f58d2f3e1f
+    hash=895daf8e1a0633698eac373d7017dbde
     =====================================
 -->
 
-# runtimepy ([4.6.1](https://pypi.org/project/runtimepy/))
+# runtimepy ([5.0.0](https://pypi.org/project/runtimepy/))
 
 [![python](https://img.shields.io/pypi/pyversions/runtimepy.svg)](https://pypi.org/project/runtimepy/)
 ![Build Status](https://github.com/vkottler/runtimepy/workflows/Python%20Package/badge.svg)
diff --git a/config b/config
index 91a822ff..be94f0ea 160000
--- a/config
+++ b/config
@@ -1 +1 @@
-Subproject commit 91a822ff4c9afcad9e62c0352975fac383ef0478
+Subproject commit be94f0eaf88b995471bc16a818ab0ba75c357454
diff --git a/local/configs/package.yaml b/local/configs/package.yaml
index 846c5eae..43927984 100644
--- a/local/configs/package.yaml
+++ b/local/configs/package.yaml
@@ -5,7 +5,7 @@ description: A framework for implementing Python services.
 entry: {{entry}}
 
 requirements:
-  - vcorelib>=3.2.6
+  - vcorelib>=3.2.8
   - svgen>=0.6.7
   - websockets
   - psutil
diff --git a/local/variables/package.yaml b/local/variables/package.yaml
index 8ee52d88..a1c4890c 100644
--- a/local/variables/package.yaml
+++ b/local/variables/package.yaml
@@ -1,5 +1,5 @@
 ---
-major: 4
-minor: 6
-patch: 1
+major: 5
+minor: 0
+patch: 0
 entry: runtimepy
diff --git a/pyproject.toml b/pyproject.toml
index 1f4aac71..95f6c410 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta:__legacy__"
 
 [project]
 name = "runtimepy"
-version = "4.6.1"
+version = "5.0.0"
 description = "A framework for implementing Python services."
 readme = "README.md"
 requires-python = ">=3.11"
diff --git a/runtimepy/__init__.py b/runtimepy/__init__.py
index 84eb050c..9947f773 100644
--- a/runtimepy/__init__.py
+++ b/runtimepy/__init__.py
@@ -1,7 +1,7 @@
 # =====================================
 # generator=datazen
 # version=3.1.4
-# hash=1f6ecacb506da0891ce4397cd8209529
+# hash=8c2e796a8c4689d3e6713f7e3647ed13
 # =====================================
 
 """
@@ -10,7 +10,7 @@
 
 DESCRIPTION = "A framework for implementing Python services."
 PKG_NAME = "runtimepy"
-VERSION = "4.6.1"
+VERSION = "5.0.0"
 
 # runtimepy-specific content.
 METRICS_NAME = "metrics"
diff --git a/runtimepy/channel/environment/__init__.py b/runtimepy/channel/environment/__init__.py
index dec6ec22..3c66d3b5 100644
--- a/runtimepy/channel/environment/__init__.py
+++ b/runtimepy/channel/environment/__init__.py
@@ -34,6 +34,12 @@ def names(self) -> _Iterator[str]:
         """Iterate over registered names in the environment."""
         yield from self.channels.names.names
 
+    def search_names(
+        self, pattern: str, exact: bool = False
+    ) -> _Iterator[str]:
+        """Search for names belonging to this environment."""
+        yield from self.channels.names.search(pattern, exact=exact)
+
     def set_default(self, key: str, default: _Default) -> None:
         """Set a new default value for a channel."""
 
diff --git a/runtimepy/control/__init__.py b/runtimepy/control/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/runtimepy/control/env/__init__.py b/runtimepy/control/env/__init__.py
new file mode 100644
index 00000000..1ef71384
--- /dev/null
+++ b/runtimepy/control/env/__init__.py
@@ -0,0 +1,56 @@
+"""
+A module implementing runtime-environment registration routines for commonly
+used control channel types.
+"""
+
+# built-in
+from typing import TypeVar
+
+# internal
+from runtimepy.channel.environment import ChannelEnvironment
+from runtimepy.primitives import AnyPrimitive
+from runtimepy.ui.controls import Controlslike
+
+T = TypeVar("T", bound=AnyPrimitive)
+
+
+def phase_angle(
+    env: ChannelEnvironment,
+    primitive: type[T],
+    name: str = "phase_angle",
+    controls: Controlslike = "phase",
+    **kwargs,
+) -> T:
+    """Create a phase-angle channel."""
+
+    prim = primitive()
+    env.channel(name, prim, commandable=True, controls=controls, **kwargs)
+    return prim  # type: ignore
+
+
+def amplitude(
+    env: ChannelEnvironment,
+    primitive: type[T],
+    name: str = "amplitude",
+    controls: Controlslike = "amplitude",
+    **kwargs,
+) -> T:
+    """Create an amplitude channel."""
+
+    prim = primitive()
+    env.channel(name, prim, commandable=True, controls=controls, **kwargs)
+    return prim  # type: ignore
+
+
+def steps(
+    env: ChannelEnvironment,
+    primitive: type[T],
+    name: str = "steps",
+    controls: Controlslike = "steps",
+    **kwargs,
+) -> T:
+    """Create a steps channel."""
+
+    prim = primitive()
+    env.channel(name, prim, commandable=True, controls=controls, **kwargs)
+    return prim  # type: ignore
diff --git a/runtimepy/control/source.py b/runtimepy/control/source.py
new file mode 100644
index 00000000..3c036206
--- /dev/null
+++ b/runtimepy/control/source.py
@@ -0,0 +1,68 @@
+"""
+A module implementing signal source structs.
+"""
+
+# built-in
+from abc import abstractmethod
+from typing import Any, Generic, cast
+
+# internal
+from runtimepy.control.env import amplitude
+from runtimepy.net.arbiter.info import RuntimeStruct
+from runtimepy.primitives import Double, T
+
+
+class PrimitiveSource(RuntimeStruct, Generic[T]):
+    """A simple output-source struct."""
+
+    kind: type[T]
+
+    outputs: list[T]
+    amplitudes: list[Double]
+
+    length: int
+
+    def init_source(self) -> None:
+        """Initialize this value source."""
+
+    @abstractmethod
+    def source(self, index: int) -> float | int | bool:
+        """Provide the next value."""
+
+    def init_env(self) -> None:
+        """Initialize this double-source environment."""
+
+        self.outputs = []
+        self.amplitudes = []
+
+        # Load 'count' from config.
+        count: int = self.config.get("count", 1)  # type: ignore
+
+        for idx in range(count):
+            # Output channel.
+            output = self.kind()
+            self.outputs.append(output)
+            self.env.channel(f"{idx}.output", output)
+
+            # Amplitude channel.
+            self.amplitudes.append(
+                amplitude(self.env, Double, name=f"{idx}.amplitude")
+            )
+
+        self.init_source()
+        self.length = len(self.outputs)
+
+    def poll(self) -> None:
+        """Update the outputs."""
+
+        for idx in range(self.length):
+            # Difficult to avoid cast.
+            self.outputs[idx].value = cast(
+                Any, self.amplitudes[idx].value * self.source(idx)
+            )
+
+
+class DoubleSource(PrimitiveSource[Double]):
+    """A simple double output source."""
+
+    kind = Double
diff --git a/runtimepy/control/step.py b/runtimepy/control/step.py
new file mode 100644
index 00000000..eeca579d
--- /dev/null
+++ b/runtimepy/control/step.py
@@ -0,0 +1,195 @@
+"""
+A module implementing a manual-stepping interface (e.g. program/human
+controlled clock).
+"""
+
+# built-in
+from typing import cast
+
+# third-party
+from vcorelib.math import (
+    RateTracker,
+    SimulatedTime,
+    default_time_ns,
+    from_nanos,
+    metrics_time_ns,
+    restore_time_source,
+    set_simulated_source,
+)
+
+# internal
+from runtimepy.net.arbiter import AppInfo
+from runtimepy.net.arbiter.info import RuntimeStruct
+from runtimepy.net.arbiter.task import ArbiterTask, TaskFactory
+from runtimepy.net.manager import ConnectionManager
+from runtimepy.net.server.websocket import RuntimepyWebsocketConnection
+from runtimepy.primitives import Bool, Double, Uint32
+
+
+def should_poll(kind: type[RuntimeStruct]) -> bool:
+    """
+    Determine if a toggle stepper should poll the provided type of struct.
+    """
+    return kind.__name__ not in {"ToggleStepper", "UiState"}
+
+
+def refresh_all_plots(manager: ConnectionManager) -> None:
+    """Signal to clients to refresh all data."""
+
+    for conn in manager.by_type(RuntimepyWebsocketConnection):
+        for interface in conn.send_interfaces.values():
+            interface({"actions": ["clear_points"]})
+
+
+class ToggleStepper(RuntimeStruct):
+    """A simple struct that ties a clock toggle to various runtime entities."""
+
+    step: Bool
+    simulate_time: Bool
+
+    time_s: Double
+
+    count: Uint32
+    counts: Uint32
+    count_rate: Double
+    count_rate_tracker: RateTracker
+
+    to_poll: set[RuntimeStruct]
+
+    timer: SimulatedTime
+
+    def _poll_time(self) -> None:
+        """Update current time."""
+        self.time_s.value = from_nanos(default_time_ns())
+
+    def init_env(self) -> None:
+        """Initialize this toggle stepper environment."""
+
+        self.step = Bool()
+        self.simulate_time = Bool()
+
+        self.time_s = Double()
+        self.env.channel(
+            "time_s",
+            self.time_s,
+            description="Current time (based on default time source).",
+        )
+        self._poll_time()
+
+        self.count = Uint32(
+            value=cast(int, self.config.get("count", 1)),
+            time_source=metrics_time_ns,
+        )
+        self.counts = Uint32(time_source=metrics_time_ns)
+
+        self.count_rate = Double(time_source=metrics_time_ns)
+        self.count_rate_tracker = RateTracker(source=metrics_time_ns)
+
+        self.to_poll = set()
+
+        self.timer = SimulatedTime(cast(int, self.config.get("step_dt_ns", 1)))
+
+        def do_step(_: bool, __: bool) -> None:
+            """Poll every step edge."""
+
+            for _ in range(self.count.raw.value):  # type: ignore
+                self.poll()
+
+        self.step.register_callback(do_step)
+
+        self.env.channel(
+            "step",
+            self.step,
+            description="Toggle to drive 'count' iterations forward.",
+            commandable=True,
+        )
+        self.env.channel(
+            "count",
+            self.count,
+            controls="steps_1_1000",
+            description="The number of iterations to step.",
+            commandable=True,
+        )
+        self.env.channel(
+            "counts", self.counts, description="Total number of counts."
+        )
+        self.env.channel(
+            "count_rate",
+            self.count_rate,
+            description="Counts per second (based on realtime clock).",
+        )
+
+        self.env.channel(
+            "simulate_time",
+            self.simulate_time,
+            description=(
+                "Whether or not time is controlled by the simulated source."
+            ),
+            commandable=True,
+        )
+
+        def do_simulate_time(_: bool, curr: bool) -> None:
+            """Toggle the time source selection."""
+
+            if curr:
+                set_simulated_source(self.timer)
+            else:
+                restore_time_source()
+
+            # Signal to the UI to clear plot data.
+            refresh_all_plots(self.app.conn_manager)
+
+            self._poll_time()
+
+        self.simulate_time.register_callback(do_simulate_time)
+
+        # Register other structs if configured to do so.
+        if self.config.get("global", True):
+            for struct in self.app.structs.values():
+                if should_poll(type(struct)):  # type: ignore
+                    self.to_poll.add(struct)  # type: ignore
+
+    def poll(self) -> None:
+        """Poll all other entities."""
+
+        self._poll_time()
+
+        for item in self.to_poll:
+            item.poll()
+
+        # Bug?
+        # pylint: disable=no-member
+        self.counts.value += 1
+        # pylint: enable=no-member
+        self.count_rate.value = self.count_rate_tracker()
+
+        self.timer.step()
+
+
+class ToggleStepperTask(ArbiterTask):
+    """A task for automatically stepping a toggle-stepper clock."""
+
+    steppers: list[ToggleStepper]
+
+    async def init(self, app: AppInfo) -> None:
+        """Initialize this task with application information."""
+
+        await super().init(app)
+        self.steppers = list(app.search_structs(ToggleStepper))
+
+        # Start paused.
+        self.paused.value = True
+
+    async def dispatch(self) -> bool:
+        """Dispatch an iteration of this task."""
+
+        for stepper in self.steppers:
+            stepper.step.toggle()
+
+        return True
+
+
+class StepperToggler(TaskFactory[ToggleStepperTask]):
+    """A task factory for toggle stepper tasks."""
+
+    kind = ToggleStepperTask
diff --git a/runtimepy/data/factories.yaml b/runtimepy/data/factories.yaml
index c1291525..4cb0019c 100644
--- a/runtimepy/data/factories.yaml
+++ b/runtimepy/data/factories.yaml
@@ -31,11 +31,14 @@ factories:
   - {name: runtimepy.task.trig.Sinusoid}
   - {name: runtimepy.task.sample.Sample}
   - {name: runtimepy.task.sample.SampleApp}
+  - {name: runtimepy.control.step.StepperToggler}
 
   # Useful structs.
   - {name: runtimepy.net.arbiter.info.TrigStruct}
   - {name: runtimepy.net.arbiter.info.SampleStruct}
   - {name: runtimepy.net.server.struct.UiState}
+  - {name: runtimepy.control.step.ToggleStepper}
+  - {name: runtimepy.noise.GaussianSource}
 
   # Useful subprocess peer interfaces.
   - {name: runtimepy.sample.peer.SamplePeer}
diff --git a/runtimepy/data/js/classes/TabInterface.js b/runtimepy/data/js/classes/TabInterface.js
index eab668f7..d833a5db 100644
--- a/runtimepy/data/js/classes/TabInterface.js
+++ b/runtimepy/data/js/classes/TabInterface.js
@@ -334,6 +334,20 @@ class TabInterface {
       }
     }
 
+    /* Handle actions. */
+    if ("actions" in data) {
+      for (let action of data["actions"]) {
+        switch (action) {
+        case "clear_points":
+          this.clearPlotPoints();
+          break;
+        default:
+          console.log(`Action '${action}' not hangled!`);
+          break;
+        }
+      }
+    }
+
     /* Stage any channel-table re-paints. */
     if (this.channels) {
       for (let key in data) {
diff --git a/runtimepy/data/server_base.yaml b/runtimepy/data/server_base.yaml
index 3a5e7e40..c4540271 100644
--- a/runtimepy/data/server_base.yaml
+++ b/runtimepy/data/server_base.yaml
@@ -10,6 +10,9 @@ ports:
 structs:
   - {name: ui, factory: ui_state}
 
+init:
+  - runtimepy.net.arbiter.housekeeping.init
+
 servers:
   - factory: runtimepy_http
     kwargs: {port: "$runtimepy_http_server"}
diff --git a/runtimepy/metrics/channel.py b/runtimepy/metrics/channel.py
index 2c743a21..e953800b 100644
--- a/runtimepy/metrics/channel.py
+++ b/runtimepy/metrics/channel.py
@@ -4,6 +4,7 @@
 
 # third-party
 from vcorelib.math import RateTracker as _RateTracker
+from vcorelib.math import metrics_time_ns as _metrics_time_ns
 
 # internal
 from runtimepy.primitives import Float as _Float
@@ -21,11 +22,15 @@ def __init__(self) -> None:
 
         self.messages = _Uint32()
         self.message_rate = _Float()
-        self._message_rate_tracker = _RateTracker(depth=METRICS_DEPTH)
+        self._message_rate_tracker = _RateTracker(
+            depth=METRICS_DEPTH, source=_metrics_time_ns
+        )
 
         self.bytes = _Uint64()
         self.kbps = _Float()
-        self._kbps_tracker = _RateTracker(depth=METRICS_DEPTH)
+        self._kbps_tracker = _RateTracker(
+            depth=METRICS_DEPTH, source=_metrics_time_ns
+        )
 
     def update(self, other: "ChannelMetrics") -> None:
         """Update values in this instance from values in another instance."""
diff --git a/runtimepy/mixins/environment.py b/runtimepy/mixins/environment.py
index 291fd84f..3c75e328 100644
--- a/runtimepy/mixins/environment.py
+++ b/runtimepy/mixins/environment.py
@@ -25,6 +25,10 @@ def __init__(self, env: ChannelEnvironment = None, **kwargs) -> None:
                 env = ChannelEnvironment(**kwargs)
             self.env = env
 
+    def __hash__(self) -> int:
+        """Get a hash for this instance."""
+        return id(self.env)
+
     def register_task_metrics(
         self, metrics: PeriodicTaskMetrics, namespace: str = METRICS_NAME
     ) -> None:
diff --git a/runtimepy/mixins/regex.py b/runtimepy/mixins/regex.py
index 978529e6..7fdf261d 100644
--- a/runtimepy/mixins/regex.py
+++ b/runtimepy/mixins/regex.py
@@ -12,7 +12,7 @@
 from vcorelib.logging import LoggerType
 
 DEFAULT_PATTERN = _compile("^[\\w\\:.-]+$")
-CHANNEL_PATTERN = _compile("^[a-z0-9_.-]+$")
+CHANNEL_PATTERN = _compile("^[a-zA-Z0-9_.-]+$")
 
 
 class RegexMixin:
diff --git a/runtimepy/mixins/trig.py b/runtimepy/mixins/trig.py
index 5345ec1d..26447d2c 100644
--- a/runtimepy/mixins/trig.py
+++ b/runtimepy/mixins/trig.py
@@ -7,7 +7,8 @@
 
 # internal
 from runtimepy.channel.environment import ChannelEnvironment
-from runtimepy.primitives import Float as _Float
+from runtimepy.control.env import amplitude, phase_angle, steps
+from runtimepy.primitives import Float
 from runtimepy.ui.controls import Controlslike
 
 
@@ -23,45 +24,22 @@ def __init__(
     ) -> None:
         """Initialize this instance."""
 
-        self.sin = _Float()
-        self.cos = _Float()
-        self.steps = _Float()
-
-        self.step_angle = float()
-
+        self.sin = Float()
+        self.cos = Float()
         env.channel("sin", self.sin)
         env.channel("cos", self.cos)
 
-        env.channel(
-            "steps",
-            self.steps,
-            commandable=True,
-            controls=steps_controls,
-        )
+        self.step_angle = float()
 
-        self.amplitude = _Float()
-        env.channel(
-            "amplitude",
-            self.amplitude,
-            commandable=True,
-            controls=amplitude_controls,
-        )
+        self.steps = steps(env, Float, controls=steps_controls)
 
-        self.sin_phase_angle = _Float()
-        self.cos_phase_angle = _Float()
+        self.amplitude = amplitude(env, Float, controls=amplitude_controls)
 
-        env.channel(
-            "sin_phase_angle",
-            self.sin_phase_angle,
-            commandable=True,
-            controls=phase_angle_controls,
+        self.sin_phase_angle = phase_angle(
+            env, Float, name="sin_phase_angle", controls=phase_angle_controls
         )
-
-        env.channel(
-            "cos_phase_angle",
-            self.cos_phase_angle,
-            commandable=True,
-            controls=phase_angle_controls,
+        self.cos_phase_angle = phase_angle(
+            env, Float, name="cos_phase_angle", controls=phase_angle_controls
         )
 
         def update_sin(_: float, __: float) -> None:
diff --git a/runtimepy/net/arbiter/base.py b/runtimepy/net/arbiter/base.py
index 94a1040a..e5e2ab49 100644
--- a/runtimepy/net/arbiter/base.py
+++ b/runtimepy/net/arbiter/base.py
@@ -28,7 +28,7 @@
     env_json_data,
     register_env,
 )
-from runtimepy.net.arbiter.housekeeping import metrics_poller
+from runtimepy.net.arbiter.housekeeping import housekeeping
 from runtimepy.net.arbiter.info import (
     AppInfo,
     ArbiterApps,
@@ -102,8 +102,11 @@ def __init__(
         self.task_manager = _ArbiterTaskManager()
 
         # Ensure that connection metrics are polled.
-        if metrics_poller_task:
-            self.task_manager.register(metrics_poller(self.manager))
+        self.task_manager.register(
+            housekeeping(
+                self.manager, poll_connection_metrics=metrics_poller_task
+            )
+        )
 
         if stop_sig is None:
             stop_sig = _asyncio.Event()
diff --git a/runtimepy/net/arbiter/housekeeping/__init__.py b/runtimepy/net/arbiter/housekeeping/__init__.py
index 0a06ab42..bfeedd13 100644
--- a/runtimepy/net/arbiter/housekeeping/__init__.py
+++ b/runtimepy/net/arbiter/housekeeping/__init__.py
@@ -12,6 +12,9 @@
 from runtimepy.net.arbiter.task import ArbiterTask as _ArbiterTask
 from runtimepy.net.arbiter.task import TaskFactory as _TaskFactory
 from runtimepy.net.manager import ConnectionManager as _ConnectionManager
+from runtimepy.primitives import Bool
+
+TASK_NAME = "housekeeping"
 
 
 class ConnectionMetricsPoller(_ArbiterTask):
@@ -28,10 +31,23 @@ def __init__(
         super().__init__(name, **kwargs)
         self.manager = manager
 
+    def _init_state(self) -> None:
+        """Add channels to this instance's channel environment."""
+
+        # Channel control for polling connection metrics.
+        self.poll_connection_metrics = Bool()
+        self.env.channel(
+            "poll_connection_metrics",
+            self.poll_connection_metrics,
+            commandable=True,
+            description="Polls application connection metrics when true.",
+        )
+
     async def dispatch(self) -> bool:
         """Dispatch an iteration of this task."""
 
-        self.manager.poll_metrics()
+        if self.poll_connection_metrics:
+            self.manager.poll_metrics()
 
         # Handle any incoming commands.
         processors = []
@@ -46,6 +62,17 @@ async def dispatch(self) -> bool:
         return True
 
 
+async def init(app: _AppInfo) -> int:
+    """Perform some initialization tasks."""
+
+    for task in app.search_tasks(ConnectionMetricsPoller):
+        task.poll_connection_metrics.value = app.config_param(
+            "poll_connection_metrics", False
+        )
+
+    return 0
+
+
 class ConnectionMetricsLogger(_ArbiterTask):
     """A task for logging metrics."""
 
@@ -73,11 +100,13 @@ class ConnectionMetricsLoggerFactory(_TaskFactory[ConnectionMetricsLogger]):
     kind = ConnectionMetricsLogger
 
 
-def metrics_poller(
-    manager: _ConnectionManager, period_s: float = 0.1
+def housekeeping(
+    manager: _ConnectionManager,
+    period_s: float = 0.1,
+    poll_connection_metrics: bool = True,
 ) -> ConnectionMetricsPoller:
     """Create a metrics-polling task."""
 
-    return ConnectionMetricsPoller(
-        "connection_metrics_poller", manager, period_s=period_s
-    )
+    task = ConnectionMetricsPoller(TASK_NAME, manager, period_s=period_s)
+    task.poll_connection_metrics.value = poll_connection_metrics
+    return task
diff --git a/runtimepy/net/arbiter/info.py b/runtimepy/net/arbiter/info.py
index 2c287b58..33be7c6b 100644
--- a/runtimepy/net/arbiter/info.py
+++ b/runtimepy/net/arbiter/info.py
@@ -62,6 +62,9 @@ async def build(self, app: "AppInfo") -> None:
         self.init_env()
 
 
+W = _TypeVar("W", bound=RuntimeStruct)
+
+
 class TrigStruct(RuntimeStruct, TrigMixin):
     """A simple trig struct."""
 
@@ -197,6 +200,17 @@ def search_tasks(self, kind: type[V], pattern: str = ".*") -> _Iterator[V]:
             if compiled.search(name) is not None and isinstance(task, kind):
                 yield task
 
+    def search_structs(
+        self, kind: type[W], pattern: str = ".*"
+    ) -> _Iterator[W]:
+        """Search for structs by type or name."""
+
+        compiled = _compile(pattern)
+
+        for name, task in self.structs.items():
+            if compiled.search(name) is not None and isinstance(task, kind):
+                yield task
+
     def single(
         self,
         *names: str,
diff --git a/runtimepy/net/manager.py b/runtimepy/net/manager.py
index 15b54195..f3e1b0ef 100644
--- a/runtimepy/net/manager.py
+++ b/runtimepy/net/manager.py
@@ -14,7 +14,7 @@
 # third-party
 from vcorelib.asyncio import log_exceptions as _log_exceptions
 from vcorelib.logging import LoggerMixin
-from vcorelib.math import default_time_ns as _default_time_ns
+from vcorelib.math import metrics_time_ns as _metrics_time_ns
 
 # internal
 from runtimepy.net.connection import Connection as _Connection
@@ -53,7 +53,7 @@ def poll_metrics(self, time_ns: int = None) -> None:
         """Poll connection metrics."""
 
         if time_ns is None:
-            time_ns = _default_time_ns()
+            time_ns = _metrics_time_ns()
 
         for conn in self._conns:
             conn.metrics.poll(time_ns=time_ns)
diff --git a/runtimepy/net/server/app/bootstrap/elements.py b/runtimepy/net/server/app/bootstrap/elements.py
index df4ee6df..c607d711 100644
--- a/runtimepy/net/server/app/bootstrap/elements.py
+++ b/runtimepy/net/server/app/bootstrap/elements.py
@@ -142,7 +142,12 @@ def slider(
 
     elem["min"] = min_val
     elem["max"] = max_val
-    elem["step"] = (max_val - min_val) / steps
+
+    step = (max_val - min_val) / steps
+    if isinstance(min_val, int) and isinstance(max_val, int):
+        step = int(step)
+
+    elem["step"] = step
 
     # add tick marks - didn't seem to work (browser didn't render anything)
 
diff --git a/runtimepy/net/server/json.py b/runtimepy/net/server/json.py
index c5697e02..b8c879cb 100644
--- a/runtimepy/net/server/json.py
+++ b/runtimepy/net/server/json.py
@@ -27,27 +27,14 @@ def default(self, o):
         return o
 
 
-def json_handler(
-    stream: TextIO,
-    request: RequestHeader,
-    response: ResponseHeader,
-    request_data: Optional[bytes],
-    data: JsonObject,
-) -> None:
-    """Create an HTTP response from some JSON object data."""
-
-    del request_data
-
-    response_type = "json"
-    response["Content-Type"] = (
-        f"application/{response_type}; charset={DEFAULT_ENCODING}"
-    )
+def traverse_dict(data: dict[str, Any], *paths: str) -> Any:
+    """Attempt to traverse a dictionary by path names."""
 
     error: dict[str, Any] = {"path": {}}
 
     # Traverse path.
     curr_path = []
-    for part in request.target.path.split("/")[2:]:
+    for part in paths:
         if not part:
             continue
 
@@ -72,11 +59,33 @@ def json_handler(
             data = error
             break
 
-        data = data[part]  # type: ignore
+        data = data[part]
 
     if callable(data):
         data = data()
 
+    return data
+
+
+def json_handler(
+    stream: TextIO,
+    request: RequestHeader,
+    response: ResponseHeader,
+    request_data: Optional[bytes],
+    data: JsonObject,
+) -> None:
+    """Create an HTTP response from some JSON object data."""
+
+    del request_data
+
+    response_type = "json"
+    response["Content-Type"] = (
+        f"application/{response_type}; charset={DEFAULT_ENCODING}"
+    )
+
+    # Traverse path.
+    data = traverse_dict(data, *request.target.path.split("/")[2:])
+
     # Use a convention for indexing data to non-dictionary leaf nodes.
     if not isinstance(data, dict):
         data = {"__raw__": data}
diff --git a/runtimepy/net/server/websocket/__init__.py b/runtimepy/net/server/websocket/__init__.py
index 211a63af..d4c8c376 100644
--- a/runtimepy/net/server/websocket/__init__.py
+++ b/runtimepy/net/server/websocket/__init__.py
@@ -5,6 +5,9 @@
 # built-in
 from collections import defaultdict
 
+# third-party
+from vcorelib.math import RateLimiter, metrics_time_ns, to_nanos
+
 # internal
 from runtimepy.message import JsonMessage
 from runtimepy.net.arbiter.tcp.json import WebsocketJsonMessageConnection
@@ -22,10 +25,7 @@ class RuntimepyWebsocketConnection(WebsocketJsonMessageConnection):
     ui_time: float
     tabs: dict[str, TabState]
 
-    # The first UI client has exclusive access to some functions, like
-    # polling metrics.
-    first_client: bool
-    first_message: bool
+    poll_governor: RateLimiter
 
     def tab_sender(self, name: str) -> TabMessageSender:
         """Get a tab message-sending interface."""
@@ -44,7 +44,7 @@ def _poll_ui_state(self, ui: UiState, time: float) -> None:
         """Update UI-specific state."""
 
         # Only one connection needs to perform this task.
-        if self.first_client or ui.env.value("num_connections") == 1:
+        if self.poll_governor():
             # Update time.
             ui.env["time_ms"] = time
             ui.env["frame_period_ms"] = time - self.ui_time
@@ -63,15 +63,6 @@ def _register_handlers(self) -> None:
         async def ui_handler(outbox: JsonMessage, inbox: JsonMessage) -> None:
             """A simple loopback handler."""
 
-            # Add to num_connections.
-            if self.first_message:
-                ui = UiState.singleton()
-                if ui and ui.env.finalized:
-                    self.first_client = (
-                        ui.env.add_int("num_connections", 1) == 1
-                    )
-                self.first_message = False
-
             # Handle frame messages.
             if "time" in inbox:
                 # Poll UI state.
@@ -109,8 +100,11 @@ def init(self) -> None:
         self.send_interfaces = {}
         self.ui_time = 0.0
         self.tabs = defaultdict(TabState.create)
-        self.first_client = False
-        self.first_message = True
+
+        # Limit UI metrics update rate to 250 Hz.
+        self.poll_governor = RateLimiter(
+            to_nanos(1.0 / 250.0), source=metrics_time_ns
+        )
 
     def disable_extra(self) -> None:
         """Additional tasks to perform when disabling."""
diff --git a/runtimepy/noise/__init__.py b/runtimepy/noise/__init__.py
new file mode 100644
index 00000000..a849c6fe
--- /dev/null
+++ b/runtimepy/noise/__init__.py
@@ -0,0 +1,19 @@
+"""
+A module implementing a structure that simulates a configurable noise source.
+"""
+
+# built-in
+import random
+
+# internal
+from runtimepy.control.source import DoubleSource
+
+
+class GaussianSource(DoubleSource):
+    """A simple output-source struct."""
+
+    def source(self, index: int) -> float:
+        """Provide the next value."""
+
+        del index
+        return random.gauss()
diff --git a/runtimepy/primitives/base.py b/runtimepy/primitives/base.py
index 5af456b8..131614c1 100644
--- a/runtimepy/primitives/base.py
+++ b/runtimepy/primitives/base.py
@@ -13,7 +13,8 @@
 from typing import TypeVar as _TypeVar
 
 # third-party
-from vcorelib.math.time import default_time_ns, nano_str
+from vcorelib.math import default_time_ns, nano_str
+from vcorelib.math.keeper import TimeSource
 
 # internal
 from runtimepy.primitives.byte_order import (
@@ -49,7 +50,10 @@ def __hash__(self) -> int:
         return self._hash
 
     def __init__(
-        self, value: T = None, scaling: ChannelScaling = None
+        self,
+        value: T = None,
+        scaling: ChannelScaling = None,
+        time_source: TimeSource = default_time_ns,
     ) -> None:
         """Initialize this primitive."""
 
@@ -58,8 +62,9 @@ def __init__(
         self.callbacks: dict[int, tuple[PrimitiveChangeCallaback[T], bool]] = (
             {}
         )
+        self.time_source = time_source
         self(value=value)
-        self.last_updated_ns: int = default_time_ns()
+        self.last_updated_ns: int = self.time_source()
         self.scaling = scaling
         self._hash = IDENT()
 
@@ -72,7 +77,7 @@ def age_ns(self, now: int = None) -> int:
         """Get the age of this primitive's value in nanoseconds."""
 
         if now is None:
-            now = default_time_ns()
+            now = self.time_source()
 
         return now - self.last_updated_ns
 
@@ -136,7 +141,7 @@ def value(self, value: T) -> None:
         curr: T = self.raw.value  # type: ignore
 
         self.raw.value = value
-        self.last_updated_ns = default_time_ns()
+        self.last_updated_ns = self.time_source()
 
         # Call callbacks if the value has changed.
         if self.callbacks and curr != value:
diff --git a/runtimepy/primitives/bool.py b/runtimepy/primitives/bool.py
index 4446b408..9ab3547e 100644
--- a/runtimepy/primitives/bool.py
+++ b/runtimepy/primitives/bool.py
@@ -13,9 +13,9 @@ class BooleanPrimitive(_Primitive[bool]):
     kind = _Bool
     value: bool
 
-    def __init__(self, value: bool = False) -> None:
+    def __init__(self, value: bool = False, **kwargs) -> None:
         """Initialize this boolean primitive."""
-        super().__init__(value=value)
+        super().__init__(value=value, **kwargs)
 
     def toggle(self) -> None:
         """Toggle the underlying value."""
diff --git a/runtimepy/primitives/float.py b/runtimepy/primitives/float.py
index 0cdc988f..f9bfdf6c 100644
--- a/runtimepy/primitives/float.py
+++ b/runtimepy/primitives/float.py
@@ -16,10 +16,10 @@ class HalfPrimitive(_Primitive[float]):
     kind = _Half
 
     def __init__(
-        self, value: float = 0.0, scaling: ChannelScaling = None
+        self, value: float = 0.0, scaling: ChannelScaling = None, **kwargs
     ) -> None:
         """Initialize this floating-point primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Half = HalfPrimitive
@@ -31,10 +31,10 @@ class FloatPrimitive(_Primitive[float]):
     kind = _Float
 
     def __init__(
-        self, value: float = 0.0, scaling: ChannelScaling = None
+        self, value: float = 0.0, scaling: ChannelScaling = None, **kwargs
     ) -> None:
         """Initialize this floating-point primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Float = FloatPrimitive
@@ -46,10 +46,10 @@ class DoublePrimitive(_Primitive[float]):
     kind = _Double
 
     def __init__(
-        self, value: float = 0.0, scaling: ChannelScaling = None
+        self, value: float = 0.0, scaling: ChannelScaling = None, **kwargs
     ) -> None:
         """Initialize this floating-point primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Double = DoublePrimitive
diff --git a/runtimepy/primitives/int.py b/runtimepy/primitives/int.py
index 31944c61..66b57dd7 100644
--- a/runtimepy/primitives/int.py
+++ b/runtimepy/primitives/int.py
@@ -23,9 +23,11 @@ class Int8Primitive(_Primitive[int]):
 
     kind = _Int8
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Int8 = Int8Primitive
@@ -36,9 +38,11 @@ class Int16Primitive(_Primitive[int]):
 
     kind = _Int16
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Int16 = Int16Primitive
@@ -49,9 +53,11 @@ class Int32Primitive(_Primitive[int]):
 
     kind = _Int32
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Int32 = Int32Primitive
@@ -62,9 +68,11 @@ class Int64Primitive(_Primitive[int]):
 
     kind = _Int64
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Int64 = Int64Primitive
@@ -75,9 +83,11 @@ class Uint8Primitive(_Primitive[int]):
 
     kind = _Uint8
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Uint8 = Uint8Primitive
@@ -88,9 +98,11 @@ class Uint16Primitive(_Primitive[int]):
 
     kind = _Uint16
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Uint16 = Uint16Primitive
@@ -101,9 +113,11 @@ class Uint32Primitive(_Primitive[int]):
 
     kind = _Uint32
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Uint32 = Uint32Primitive
@@ -114,9 +128,11 @@ class Uint64Primitive(_Primitive[int]):
 
     kind = _Uint64
 
-    def __init__(self, value: int = 0, scaling: ChannelScaling = None) -> None:
+    def __init__(
+        self, value: int = 0, scaling: ChannelScaling = None, **kwargs
+    ) -> None:
         """Initialize this integer primitive."""
-        super().__init__(value=value, scaling=scaling)
+        super().__init__(value=value, scaling=scaling, **kwargs)
 
 
 Uint64 = Uint64Primitive
diff --git a/runtimepy/requirements.txt b/runtimepy/requirements.txt
index f05e2eb0..37e7a78f 100644
--- a/runtimepy/requirements.txt
+++ b/runtimepy/requirements.txt
@@ -1,4 +1,4 @@
-vcorelib>=3.2.6
+vcorelib>=3.2.8
 svgen>=0.6.7
 websockets
 psutil
diff --git a/runtimepy/struct/dither.py b/runtimepy/struct/dither.py
deleted file mode 100644
index a800700b..00000000
--- a/runtimepy/struct/dither.py
+++ /dev/null
@@ -1,3 +0,0 @@
-"""
-A module implementing a structure for a dithering controller.
-"""
diff --git a/runtimepy/subprocess/protocol.py b/runtimepy/subprocess/protocol.py
index 26db8af1..a1c2272e 100644
--- a/runtimepy/subprocess/protocol.py
+++ b/runtimepy/subprocess/protocol.py
@@ -15,7 +15,7 @@
 from typing import Optional, cast
 
 # third-party
-from vcorelib.math import default_time_ns
+from vcorelib.math import metrics_time_ns
 
 
 class RuntimepySubprocessProtocol(SubprocessProtocol):
@@ -56,7 +56,7 @@ def pid(self) -> int:
     def connection_made(self, transport) -> None:
         """Initialize this protocol."""
 
-        self.start_time = default_time_ns()
+        self.start_time = metrics_time_ns()
         self.elapsed_time = -1
 
         self.stdout_queue = None
@@ -105,7 +105,7 @@ def _flush_stderr(self) -> None:
     def process_exited(self) -> None:
         """Handle process exit."""
 
-        self.elapsed_time = default_time_ns() - self.start_time
+        self.elapsed_time = metrics_time_ns() - self.start_time
 
         self._flush_stdout()
         self._flush_stderr()
diff --git a/runtimepy/task/basic/periodic.py b/runtimepy/task/basic/periodic.py
index 58b72487..f8007c9a 100644
--- a/runtimepy/task/basic/periodic.py
+++ b/runtimepy/task/basic/periodic.py
@@ -65,10 +65,10 @@ def __init__(
         self.register_task_metrics(self.metrics)
 
         # State.
-        self._paused = _Bool()
+        self.paused = _Bool()
         self.env.channel(
             "paused",
-            self._paused,
+            self.paused,
             commandable=True,
             description="Whether or not this task is paused.",
         )
@@ -147,7 +147,7 @@ async def run(
 
         while self._enabled:
             # When paused, don't run the iteration itself.
-            if not self._paused:
+            if not self.paused:
                 with self.metrics.measure(
                     eloop,
                     self._dispatch_rate,
diff --git a/runtimepy/task/sample.py b/runtimepy/task/sample.py
index adf1d572..df5a9f6b 100644
--- a/runtimepy/task/sample.py
+++ b/runtimepy/task/sample.py
@@ -16,7 +16,7 @@
 
 
 class SampleTask(ArbiterTask, TrigMixin):
-    """A base TUI application."""
+    """A sample application."""
 
     async def init(self, app: AppInfo) -> None:
         """Initialize this task with application information."""
@@ -52,7 +52,7 @@ async def dispatch(self) -> bool:
 
 
 class Sample(TaskFactory[SampleTask]):
-    """A TUI application factory."""
+    """A sample-task application factory."""
 
     kind = SampleTask
 
diff --git a/runtimepy/ui/controls.py b/runtimepy/ui/controls.py
index 5d92d02a..0f0cf23b 100644
--- a/runtimepy/ui/controls.py
+++ b/runtimepy/ui/controls.py
@@ -32,14 +32,15 @@ def make_slider(
 
 CANONICAL: dict[str, Controls] = {
     "phase": make_slider(-math.pi, math.pi, 90, default=0.0),
+    "amplitude": make_slider(0.0, 2.0, 100.0, default=1.0),
+    "period": make_slider(0.0, 0.05, 100.0, default=0.01),
     "steps": make_slider(
         DEFAULT_STEPS / 4,
         DEFAULT_STEPS * 4,
         DEFAULT_STEPS * 2,
         default=DEFAULT_STEPS,
     ),
-    "amplitude": make_slider(0.0, 2.0, 40.0, default=1.0),
-    "period": make_slider(0.0, 0.05, 100.0, default=0.01),
+    "steps_1_1000": make_slider(1, 1000, 100, default=1),
 }
 
 
diff --git a/tasks/noise.yaml b/tasks/noise.yaml
new file mode 100644
index 00000000..4265b75a
--- /dev/null
+++ b/tasks/noise.yaml
@@ -0,0 +1,13 @@
+---
+includes:
+  - default.yaml
+
+tasks:
+  - {name: clock_task, factory: stepper_toggler}
+
+structs:
+  - name: clock
+    factory: toggle_stepper
+  - name: noise
+    factory: gaussian_source
+    config: {count: 4}
diff --git a/tests/channel/environment/test_create.py b/tests/channel/environment/test_create.py
index d6cc9136..b50d2329 100644
--- a/tests/channel/environment/test_create.py
+++ b/tests/channel/environment/test_create.py
@@ -26,6 +26,8 @@ def test_channel_environment_create_basic():
     )
     assert result
 
+    assert len(list(env.search_names("sample_channel", exact=True))) == 1
+
     env.age_ns("sample_channel")
 
     name = "test_field"
diff --git a/tests/commands/test_arbiter.py b/tests/commands/test_arbiter.py
index 8cbd3ead..161223f3 100644
--- a/tests/commands/test_arbiter.py
+++ b/tests/commands/test_arbiter.py
@@ -26,7 +26,7 @@ def test_arbiter_command_basic():
         == 0
     )
 
-    for entry in ["basic", "http"]:
+    for entry in ["basic", "http", "control"]:
         assert (
             runtimepy_main(
                 base + [str(resource("connection_arbiter", f"{entry}.yaml"))]
diff --git a/tests/control/__init__.py b/tests/control/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/control/test_step.py b/tests/control/test_step.py
new file mode 100644
index 00000000..39056a4a
--- /dev/null
+++ b/tests/control/test_step.py
@@ -0,0 +1,33 @@
+"""
+Test the 'control.step' module.
+"""
+
+# module under test
+from runtimepy.control.step import ToggleStepper, ToggleStepperTask
+from runtimepy.net.arbiter.info import AppInfo
+
+
+async def controls_test(app: AppInfo) -> int:
+    """Test JSON clients in parallel."""
+
+    toggler = list(app.search_tasks(ToggleStepperTask))[0]
+    toggler.paused.value = False
+
+    stepper = list(app.search_structs(ToggleStepper))[0]
+
+    stepper.step.toggle()
+    stepper.step.toggle()
+
+    stepper.simulate_time.toggle()
+
+    stepper.step.toggle()
+    stepper.step.toggle()
+
+    stepper.simulate_time.toggle()
+
+    stepper.step.toggle()
+    stepper.step.toggle()
+
+    assert await toggler.dispatch()
+
+    return 0
diff --git a/tests/data/valid/connection_arbiter/control.yaml b/tests/data/valid/connection_arbiter/control.yaml
new file mode 100644
index 00000000..c5a3697b
--- /dev/null
+++ b/tests/data/valid/connection_arbiter/control.yaml
@@ -0,0 +1,16 @@
+---
+includes:
+  - package://runtimepy/factories.yaml
+
+tasks:
+  - {name: clock_task, factory: stepper_toggler}
+
+structs:
+  - name: clock
+    factory: toggle_stepper
+  - name: noise
+    factory: gaussian_source
+    config: {count: 4}
+
+app:
+  - tests.control.test_step.controls_test
diff --git a/tests/data/valid/connection_arbiter/runtimepy_http.yaml b/tests/data/valid/connection_arbiter/runtimepy_http.yaml
index 6a98840a..111f8975 100644
--- a/tests/data/valid/connection_arbiter/runtimepy_http.yaml
+++ b/tests/data/valid/connection_arbiter/runtimepy_http.yaml
@@ -5,6 +5,12 @@ includes_left:
 app:
   - tests.net.stream.runtimepy_http_test
 
+structs:
+  - name: clock
+    factory: toggle_stepper
+  - name: noise
+    factory: gaussian_source
+
 config:
   experimental: true
   foo: bar
diff --git a/tests/net/server/test_json.py b/tests/net/server/test_json.py
new file mode 100644
index 00000000..b0f1ae76
--- /dev/null
+++ b/tests/net/server/test_json.py
@@ -0,0 +1,15 @@
+"""
+Test the 'net.server.json' module.
+"""
+
+# module under test
+from runtimepy.net.server.json import traverse_dict
+
+
+def test_traverse_dict_basic():
+    """Test basic dict-traversing scenarios."""
+
+    src = {"a": lambda: {"a": 1, "b": 2, "c": 3}}
+
+    assert traverse_dict(src, "", "a") == {"a": 1, "b": 2, "c": 3}
+    assert traverse_dict(src, "a", "b") == 2
diff --git a/tests/net/stream/__init__.py b/tests/net/stream/__init__.py
index 1ed9aee8..31a8cf3c 100644
--- a/tests/net/stream/__init__.py
+++ b/tests/net/stream/__init__.py
@@ -13,6 +13,7 @@
 
 # module under test
 from runtimepy import PKG_NAME
+from runtimepy.control.step import ToggleStepper
 from runtimepy.message import JsonMessage
 from runtimepy.net.arbiter.info import AppInfo
 from runtimepy.net.http.header import RequestHeader
@@ -110,6 +111,11 @@ async def runtimepy_http_test(app: AppInfo) -> int:
         app.single(pattern="client", kind=RuntimepyWebsocketConnection)
     )
 
+    # Find stepper struct, toggle 'simualte_time' twice.
+    for inst in app.search_structs(ToggleStepper):
+        inst.simulate_time.toggle()
+        inst.simulate_time.toggle()
+
     return 0