diff --git a/Cargo.lock b/Cargo.lock
index a4de047ff..f88410147 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4819,6 +4819,7 @@ dependencies = [
 name = "tor-rtmock"
 version = "0.8.2"
 dependencies = [
+ "amplify",
  "async-trait",
  "educe",
  "futures",
diff --git a/crates/tor-rtmock/Cargo.toml b/crates/tor-rtmock/Cargo.toml
index c86bb4a4c..9c2a5d7af 100644
--- a/crates/tor-rtmock/Cargo.toml
+++ b/crates/tor-rtmock/Cargo.toml
@@ -12,6 +12,7 @@ categories = ["asynchronous"]
 repository = "https://gitlab.torproject.org/tpo/core/arti.git/"
 
 [dependencies]
+amplify = { version = "4", default-features = false, features = ["derive"] }
 async-trait = "0.1.54"
 educe = "0.4.6"
 futures = "0.3.14"
diff --git a/crates/tor-rtmock/src/lib.rs b/crates/tor-rtmock/src/lib.rs
index a85d5946f..4d356422c 100644
--- a/crates/tor-rtmock/src/lib.rs
+++ b/crates/tor-rtmock/src/lib.rs
@@ -51,7 +51,9 @@ pub mod task;
 pub mod time;
 
 mod net_runtime;
+mod runtime;
 mod sleep_runtime;
 
 pub use net_runtime::MockNetRuntime;
+pub use runtime::MockRuntime;
 pub use sleep_runtime::MockSleepRuntime;
diff --git a/crates/tor-rtmock/src/runtime.rs b/crates/tor-rtmock/src/runtime.rs
new file mode 100644
index 000000000..201ce32e4
--- /dev/null
+++ b/crates/tor-rtmock/src/runtime.rs
@@ -0,0 +1,129 @@
+//! Completely mock runtime
+
+use amplify::Getters;
+
+use crate::util::impl_runtime_prelude::*;
+
+use crate::net::MockNetProvider;
+use crate::task::MockExecutor;
+use crate::time::MockSleepProvider;
+
+/// Completely mock runtime
+///
+/// Suitable for test cases that wish to completely control
+/// the environment experienced by the code under test.
+///
+/// # Restrictions
+///
+/// The test case must advance the mock time explicitly as desired.
+/// There is not currently any facility for automatically
+/// making progress by advancing the mock time by the right amounts
+/// for the timeouts set by the futures under test.
+// ^ I think such a facility could be provided.  `MockSleepProvider` would have to
+//   provide a method to identify the next interesting time event.
+//   The waitfor machinery in MockSleepProvider and MockSleepRuntime doesn't seem suitable.
+///
+/// Tests that use this runtime *must not* interact with the outside world;
+/// everything must go through this runtime (and its pieces).
+///
+/// Use of inter-future communication facilities from `futures`
+/// or other runtime-agnostic crates is permitted.
+#[derive(Debug, Default, Clone, Getters)]
+#[getter(prefix = "mock_")]
+pub struct MockRuntime {
+    /// Tasks
+    task: MockExecutor,
+    /// Time provider
+    sleep: MockSleepProvider,
+    /// Net provider
+    net: MockNetProvider,
+}
+
+/// Builder for a manually-configured `MockRuntime`
+#[derive(Debug, Default, Clone)]
+pub struct MockRuntimeBuilder {
+    /// starting wall clock time
+    starting_wallclock: Option<SystemTime>,
+}
+
+impl_runtime! {
+    [ ] MockRuntime,
+    spawn: task,
+    block: task,
+    sleep: sleep: MockSleepProvider,
+    net: net: MockNetProvider,
+}
+
+impl MockRuntime {
+    /// Create a new `MockRuntime` with default parameters
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Return a builder, for creating a `MockRuntime` with some parameters manually configured
+    pub fn builder() -> MockRuntimeBuilder {
+        Default::default()
+    }
+
+    /// Run tasks in the current executor until every task except this one is waiting
+    ///
+    /// Calls [`MockExecutor::progress_until_stalled()`].
+    ///
+    /// # Restriction - no automatic time advance
+    ///
+    /// The mocked time will *not* be automatically advanced.
+    ///
+    /// Usually
+    /// (and especially if the tasks under test are waiting for timeouts or periodic events)
+    /// you must use
+    /// [`advance()`](MockRuntime::advance)
+    /// or
+    /// [`jump_to()`](MockRuntime::jump_to)
+    /// to ensure the simulated time progresses as required.
+    ///
+    /// # Panics
+    ///
+    /// Might malfunction or panic if more than one such call is running at once.
+    ///
+    /// (Ie, you must `.await` or drop the returned `Future`
+    /// before calling this method again.)
+    pub async fn progress_until_stalled(&self) {
+        self.task.progress_until_stalled().await;
+    }
+
+    /// See [`MockSleepProvider::advance()`]
+    pub async fn advance(&self, dur: Duration) {
+        self.sleep.advance(dur).await;
+    }
+    /// See [`MockSleepProvider::jump_to()`]
+    pub fn jump_to(&self, new_wallclock: SystemTime) {
+        self.sleep.jump_to(new_wallclock);
+    }
+}
+
+impl MockRuntimeBuilder {
+    /// Set the starting wall clock time
+    pub fn starting_wallclock(mut self, starting_wallclock: SystemTime) -> Self {
+        self.starting_wallclock = Some(starting_wallclock);
+        self
+    }
+
+    /// Build the runtime
+    pub fn build(self) -> MockRuntime {
+        let MockRuntimeBuilder {
+            scheduling,
+            starting_wallclock,
+        } = self;
+
+        let sleep = if let Some(starting_wallclock) = starting_wallclock {
+            MockSleepProvider::new(starting_wallclock)
+        } else {
+            MockSleepProvider::default()
+        };
+
+        MockRuntime {
+            sleep,
+            ..Default::default()
+        }
+    }
+}