From ed1d5fe21efbe7ed111360203805bdb20989e139 Mon Sep 17 00:00:00 2001
From: Zachery Aaron Shores-Chmielewski <zacheryasc@gmail.com>
Date: Sat, 18 Jul 2026 15:21:34 +0400
Subject: [PATCH] refactor(process): process-manager cleanup
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Replace the driver/session/action/event abstraction with a single OS-process supervisor thread and a minimal lifecycle-only public API.

- supervisor: add a dedicated swactor-process-supervisor thread that owns the child, runs it with null stdio, wakes via an eventfd plus poll(2), reaps with waitpid(WNOHANG), and escalates SIGTERM to SIGKILL after a deadline, reporting only lifecycle ThreadEvents over a SegQueue plus wake channel
- actor: collapse ProcessActor<D> into a non-generic state machine (Spawning/Running/Stopping/Done) that owns the supervisor handle, drains events on SupervisorWake, forwards lifecycle as ProcessOutput, and triggers shutdown_now in on_stop
- lifecycle: add ProcessOutputConfig (Disabled/DatastreamMirror) with a JSON proc.<label>.lifecycle mirror (schema swactor_process.lifecycle.v1), command-basename label derivation/sanitization, and an RAII reservation registry preventing duplicate channels
- message/types/spawn/lib: trim the API — ProcessCommand is now only Stop { kill_after }, ProcessOutput covers Started/SpawnFailed/Exited/Error, ProcessSpec keeps command/args/env/working_dir/label; re-export spawn_local_process/send_process_command and drop the custom-driver spawn_process
- removed: delete the action/event/local/mock/session modules and the ProcessDriver/ProcessWaker/EventQueue/PtySize/ProcessMode types plus the old test suite (actor_scenarios, e2e_process, local_driver, proptest_session, session_scenarios); add public_api_stage1/2 tests and the SWACTOR_MANAGED_PROCESS_SPEC.md
- swactor core: demote ProcessOutputObserver to a legacy/custom adapter (no longer auto-attached), remove Runtime::set_process_output_observer and Ctx::process_output_observer, and add the datastream dependency to the process crate for the mirror

Signed-off-by: Zachery Aaron Shores-Chmielewski <zacheryasc@gmail.com>
---
 Cargo.lock                                    |   2 -
 crates/datastream/src/emit.rs                 |   1 +
 crates/datastream/src/endpoint.rs             |   2 +-
 crates/process/Cargo.toml                     |   5 +-
 .../process/SWACTOR_MANAGED_PROCESS_SPEC.md   | 327 ++++++
 crates/process/src/action.rs                  |  53 -
 crates/process/src/actor.rs                   | 383 ++++---
 crates/process/src/event.rs                   |  71 --
 crates/process/src/lib.rs                     |  32 +-
 crates/process/src/lifecycle.rs               | 321 ++++++
 crates/process/src/local/mod.rs               | 291 ------
 crates/process/src/message.rs                 |  72 +-
 crates/process/src/mock.rs                    |  61 --
 crates/process/src/session.rs                 | 398 -------
 crates/process/src/spawn.rs                   |  97 +-
 crates/process/src/supervisor.rs              | 955 +++++++++++++++++
 crates/process/src/types.rs                   | 155 +--
 crates/process/tests/actor_scenarios.rs       | 570 ----------
 crates/process/tests/e2e_process.rs           | 269 -----
 crates/process/tests/local_driver.rs          | 342 ------
 crates/process/tests/proptest_session.rs      | 203 ----
 crates/process/tests/public_api_stage1.rs     |  54 +
 crates/process/tests/public_api_stage2.rs     | 974 ++++++++++++++++++
 crates/process/tests/session_scenarios.rs     | 787 --------------
 src/actor.rs                                  |   8 -
 src/process_observer.rs                       |  24 +-
 src/runtime.rs                                |  11 -
 27 files changed, 2943 insertions(+), 3525 deletions(-)
 create mode 100644 crates/process/SWACTOR_MANAGED_PROCESS_SPEC.md
 delete mode 100644 crates/process/src/action.rs
 delete mode 100644 crates/process/src/event.rs
 create mode 100644 crates/process/src/lifecycle.rs
 delete mode 100644 crates/process/src/local/mod.rs
 delete mode 100644 crates/process/src/mock.rs
 delete mode 100644 crates/process/src/session.rs
 create mode 100644 crates/process/src/supervisor.rs
 delete mode 100644 crates/process/tests/actor_scenarios.rs
 delete mode 100644 crates/process/tests/e2e_process.rs
 delete mode 100644 crates/process/tests/local_driver.rs
 delete mode 100644 crates/process/tests/proptest_session.rs
 create mode 100644 crates/process/tests/public_api_stage1.rs
 create mode 100644 crates/process/tests/public_api_stage2.rs
 delete mode 100644 crates/process/tests/session_scenarios.rs

diff --git a/Cargo.lock b/Cargo.lock
index d1e1c1e..1e7fdc6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4346,8 +4346,6 @@ dependencies = [
  "crossbeam-queue",
  "datastream",
  "libc",
- "proptest",
- "proptest-state-machine",
  "serde",
  "serde_json",
  "serde_yaml",
diff --git a/crates/datastream/src/emit.rs b/crates/datastream/src/emit.rs
index 290b22b..80e1aec 100644
--- a/crates/datastream/src/emit.rs
+++ b/crates/datastream/src/emit.rs
@@ -89,6 +89,7 @@ impl DatastreamEmitter {
         self.mux.submit(channel, text.into_bytes())
     }
 
+    /// Build a legacy/custom process-output observer that writes chunks into this mux.
     pub fn process_observer_with<F>(&self, channel_for: F) -> Arc<dyn ProcessOutputObserver>
     where
         F: Fn(&str, bool) -> ChannelId + Send + Sync + 'static,
diff --git a/crates/datastream/src/endpoint.rs b/crates/datastream/src/endpoint.rs
index c317402..5ca8721 100644
--- a/crates/datastream/src/endpoint.rs
+++ b/crates/datastream/src/endpoint.rs
@@ -718,7 +718,7 @@ fn register_channel(
     Ok(id)
 }
 
-/// Managed-process output observer that submits stdout/stderr chunks as frames.
+/// Legacy/custom process-output observer adapter that submits stdout/stderr chunks as frames.
 pub struct DatastreamProcessObserver {
     producer: DatastreamProducer,
     channel_for: Arc<dyn Fn(&str, bool) -> ChannelId + Send + Sync>,
diff --git a/crates/process/Cargo.toml b/crates/process/Cargo.toml
index fc1da20..9bce661 100644
--- a/crates/process/Cargo.toml
+++ b/crates/process/Cargo.toml
@@ -5,12 +5,9 @@ edition = "2024"
 
 [dependencies]
 swactor = { path = "../..", default-features = false, features = ["no_random"] }
+datastream = { path = "../datastream" }
 crossbeam-queue = "0.3.12"
 libc = "0.2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 serde_yaml = "0.9"
-
-[dev-dependencies]
-proptest = "1"
-proptest-state-machine = "0.3"
diff --git a/crates/process/SWACTOR_MANAGED_PROCESS_SPEC.md b/crates/process/SWACTOR_MANAGED_PROCESS_SPEC.md
new file mode 100644
index 0000000..c715f93
--- /dev/null
+++ b/crates/process/SWACTOR_MANAGED_PROCESS_SPEC.md
@@ -0,0 +1,327 @@
+# Swactor Managed Process Specification
+
+**Status:** current contract for `swactor-process`.
+
+`swactor-process` provides a Swactor actor interface for launching, supervising,
+stopping, and observing one operating-system child process per process actor.
+
+The crate owns process lifecycle/control only. Child stdin/stdout/stderr are not
+managed or observed by this crate.
+
+---
+
+## 1. Public API
+
+The crate exports:
+
+```text
+ProcessSpec
+ProcessLifecycleObservability
+ProcessOutputConfig
+ProcessCommand
+ProcessOutput
+ExitStatus
+spawn_local_process
+send_process_command
+```
+
+Pipeline and YAML exports are separate crate features and are not part of the
+managed-process protocol described here.
+
+### 1.1 ProcessSpec
+
+```text
+ProcessSpec {
+    command: String,
+    args: Vec<String>,
+    env: HashMap<String, String>,
+    working_dir: Option<PathBuf>,
+    label: Option<String>,
+}
+```
+
+`command` is passed directly to `std::process::Command::new`.
+
+`args` are passed as direct argv entries. The crate does not split, quote,
+unquote, expand, or shell-parse argument strings.
+
+`env` contains child environment overrides.
+
+`working_dir`, when present, is passed as the child current working directory.
+
+`label`, when present, is the lifecycle datastream label source. When `label` is
+absent, the label source is the basename of `command`.
+
+### 1.2 ProcessOutputConfig
+
+```text
+ProcessOutputConfig::disabled(upstream: ActorAddress) -> ProcessOutputConfig
+ProcessOutputConfig::datastream_mirror(
+    upstream: ActorAddress,
+    producer: DatastreamProducer,
+) -> ProcessOutputConfig
+ProcessOutputConfig::upstream(&self) -> ActorAddress
+ProcessOutputConfig::observability(&self) -> ProcessLifecycleObservability
+```
+
+`upstream` is the actor address that receives every public `ProcessOutput`.
+
+`disabled` sends only upstream `ProcessOutput`.
+
+`datastream_mirror` sends upstream `ProcessOutput` and also mirrors each
+lifecycle/control output to one datastream channel.
+
+### 1.3 ProcessLifecycleObservability
+
+```text
+ProcessLifecycleObservability::Disabled
+ProcessLifecycleObservability::DatastreamMirror
+```
+
+This setting controls lifecycle/control mirroring only. It does not enable child
+stdin/stdout/stderr handling.
+
+### 1.4 ProcessCommand
+
+```text
+ProcessCommand::Stop {
+    kill_after: Option<Duration>,
+}
+```
+
+`Stop` asks the supervisor to terminate the child process. `kill_after`, when
+present, is the grace duration before kill escalation.
+
+### 1.5 ProcessOutput
+
+```text
+ProcessOutput::Started { pid: u32 }
+ProcessOutput::SpawnFailed { error: String }
+ProcessOutput::Exited { status: ExitStatus }
+ProcessOutput::Error { error: String }
+```
+
+`Started` means the OS child spawned and `pid` is the child process id.
+
+`SpawnFailed` means the process actor was created but the OS child did not spawn.
+
+`Exited` means the OS child reached a terminal status.
+
+`Error` means the process supervisor or process actor hit an operational failure
+other than OS spawn failure.
+
+### 1.6 ExitStatus
+
+```text
+ExitStatus::Code(i32)
+ExitStatus::Signal(i32)
+ExitStatus::Unknown
+```
+
+### 1.7 Spawn and command helpers
+
+```text
+spawn_local_process(
+    ctx: &Ctx,
+    sender: &ExternalSender,
+    spec: ProcessSpec,
+    output: ProcessOutputConfig,
+) -> Result<ActorAddress, Error>
+```
+
+`spawn_local_process` validates lifecycle output configuration, creates one
+process actor, wires its private supervisor wake path, and returns the process
+actor address.
+
+Success from `spawn_local_process` means the process actor was created. It does
+not mean the OS child spawned successfully. OS spawn success or failure is
+reported later as `ProcessOutput`.
+
+```text
+send_process_command(
+    sender: &ExternalSender,
+    process: ActorAddress,
+    command: ProcessCommand,
+) -> Result<(), Error>
+```
+
+`send_process_command` is the public helper for sending process commands. It
+wraps the public `ProcessCommand` in the actor's private mailbox type.
+
+---
+
+## 2. Runtime topology
+
+One process actor owns one OS child process lifecycle.
+
+The actor owns:
+
+- lifecycle state;
+- the configured upstream output address;
+- optional lifecycle datastream mirror state;
+- a private supervisor thread handle.
+
+The private supervisor thread owns:
+
+- the child process handle and pid;
+- blocking-prone child exit polling;
+- terminate/kill signal delivery;
+- the stop kill deadline.
+
+The child process owns its own execution.
+
+The supervisor thread is not a public actor and not a public extension point.
+
+---
+
+## 3. Child spawn behavior
+
+The supervisor starts the child with:
+
+```text
+Command::new(&spec.command)
+cmd.args(&spec.args)
+cmd.env(key, value) for each spec.env entry
+cmd.current_dir(dir) when spec.working_dir is Some(dir)
+cmd.stdin(Stdio::null())
+cmd.stdout(Stdio::null())
+cmd.stderr(Stdio::null())
+cmd.spawn()
+```
+
+The crate does not invoke a shell unless the caller explicitly sets `command` to
+a shell executable and supplies shell arguments.
+
+Child stdin/stdout/stderr are connected to null handles. The managed-process
+protocol does not expose stdin writes, stdout/stderr output events, PTY resize,
+or arbitrary signal commands.
+
+If `cmd.spawn()` fails, the actor emits exactly one terminal
+`ProcessOutput::SpawnFailed { error }` and does not emit `Started`, `Exited`, or
+`Error` for that spawn failure.
+
+---
+
+## 4. Lifecycle output delivery
+
+The actor sends each public `ProcessOutput` to the configured upstream actor.
+
+When `ProcessOutputConfig::datastream_mirror` is used, the actor also mirrors
+each output to the configured datastream producer. Datastream submit failure is
+ignored and does not suppress upstream output or emit `ProcessOutput::Error`.
+
+Public lifecycle/control output order follows observed lifecycle:
+
+- successful spawn emits `Started` before any terminal `Exited`;
+- spawn failure emits `SpawnFailed` without `Started` or `Exited`;
+- supervisor failure emits `Error`;
+- after a terminal output, later public stop attempts emit no additional
+  `ProcessOutput`.
+
+---
+
+## 5. Lifecycle datastream labels and records
+
+The label source is:
+
+1. `ProcessSpec::label`, when present;
+2. otherwise, the final non-empty path segment of `ProcessSpec::command`;
+3. otherwise, the full `command` string.
+
+The label sanitizer:
+
+- trims source whitespace;
+- lowercases ASCII alphanumeric characters;
+- preserves `_` and `-`;
+- replaces every other character with `_`;
+- collapses repeated `_`;
+- trims leading and trailing `_`;
+- rejects an empty sanitized result with:
+
+```text
+invalid process lifecycle label: empty segment
+```
+
+The lifecycle channel name is:
+
+```text
+proc.<label>.lifecycle
+```
+
+When lifecycle mirroring is enabled, the channel is registered as:
+
+```text
+ChannelContent::JsonRecord {
+    schema: Some("swactor_process.lifecycle.v1")
+}
+```
+
+Duplicate lifecycle labels on the same datastream stream are rejected before the
+process actor is spawned with an error containing:
+
+```text
+duplicate process lifecycle datastream channel: proc.<label>.lifecycle on stream <stream>
+```
+
+Lifecycle JSON records are:
+
+```json
+{"event":"started","pid":123}
+{"event":"spawn_failed","error":"..."}
+{"event":"exited","status":{"kind":"code","value":0}}
+{"event":"exited","status":{"kind":"signal","value":9}}
+{"event":"exited","status":{"kind":"unknown"}}
+{"event":"error","error":"..."}
+```
+
+The managed-process core registers no `proc.<label>.stdout` or
+`proc.<label>.stderr` channels.
+
+---
+
+## 6. Stop semantics
+
+Use `send_process_command` with `ProcessCommand::Stop { kill_after }` to request
+shutdown.
+
+If stop is requested before the child reports successful spawn, the actor queues
+the stop intent. When the child later starts, the actor still emits `Started`
+first, asks the supervisor to terminate the child, and later emits terminal
+`Exited` unless a supervisor failure occurs.
+
+If stop is requested before an OS spawn failure is reported, the actor still
+emits only `SpawnFailed` for that failed spawn.
+
+If the child is running, stop sends terminate to the child process.
+
+If `kill_after` is `Some(duration)`, the supervisor sends kill after that
+deadline if the child has not exited.
+
+If `kill_after` is `None`, the supervisor does not schedule kill escalation.
+
+Duplicate stop while already stopping is a no-op. It does not tighten, extend,
+or replace the original kill deadline.
+
+Stop after terminal output is a no-op if the actor is still alive. If the actor
+has already stopped, sending the command may fail at the runtime address layer;
+that failure does not produce process output.
+
+---
+
+## 7. Actor and supervisor cleanup
+
+The actor uses a private mailbox wrapper so supervisor wake messages and public
+process commands share one actor input type without changing the Swactor runtime.
+
+The actor drains supervisor events when it starts, when it receives a supervisor
+wake, and before/after applying a public stop command.
+
+The supervisor sends a private `ThreadFinished` event when its thread reaches the
+end of process supervision. The actor stops itself only after a terminal state is
+recorded and the supervisor handle has been cleared.
+
+If the actor stops while the supervisor is still present, it sends best-effort
+shutdown to the supervisor without blocking for a waiting join.
+
+Dropping the supervisor handle sends best-effort shutdown and joins only when
+the thread is already finished.
diff --git a/crates/process/src/action.rs b/crates/process/src/action.rs
deleted file mode 100644
index 6ded095..0000000
--- a/crates/process/src/action.rs
+++ /dev/null
@@ -1,53 +0,0 @@
-use std::time::Duration;
-
-use crate::types::{ExitStatus, ProcessError, ProcessSpec, PtySize, Signal};
-use swactor::actor::ActorAddress;
-
-/// Which output stream produced data.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum OutputStream {
-    Stdout,
-    Stderr,
-}
-
-/// Actions emitted by ProcessSession for the driver or actor layer to execute.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum ProcessAction {
-    // --- Driver commands ---
-    /// Spawn the process described by the spec.
-    SpawnProcess { spec: ProcessSpec },
-    /// Write bytes to the process's stdin.
-    WriteStdin { data: Vec<u8> },
-    /// Send a signal to the process.
-    SendSignal { signal: Signal },
-    /// Resize the process's PTY.
-    ResizePty { size: PtySize },
-    /// Close the process's stdin pipe.
-    CloseStdin,
-    /// Schedule a kill timeout that fires KillTimeout after the given duration.
-    ScheduleKillTimeout { duration: Duration },
-
-    // --- Subscriber notifications ---
-    /// Notify subscribers that the process started.
-    NotifyStarted { subscribers: Vec<ActorAddress> },
-    /// Notify subscribers of output.
-    NotifyOutput {
-        subscribers: Vec<ActorAddress>,
-        data: Vec<u8>,
-        stream: OutputStream,
-    },
-    /// Notify subscribers that the process exited.
-    NotifyExited {
-        subscribers: Vec<ActorAddress>,
-        status: ExitStatus,
-    },
-    /// Notify subscribers of an error.
-    NotifyError {
-        subscribers: Vec<ActorAddress>,
-        error: ProcessError,
-    },
-
-    // --- Lifecycle ---
-    /// The session is done; the owning actor should stop itself.
-    SelfTerminate,
-}
diff --git a/crates/process/src/actor.rs b/crates/process/src/actor.rs
index d10bb32..f52bea3 100644
--- a/crates/process/src/actor.rs
+++ b/crates/process/src/actor.rs
@@ -1,174 +1,283 @@
 use std::sync::{Arc, OnceLock};
 
 use swactor::actor::{ActorAddress, ActorInterface, Ctx};
-use swactor::process_observer::ProcessOutputObserver;
+use swactor::runtime::ExternalSender;
 
-use crate::action::{OutputStream, ProcessAction};
-use crate::event::ProcessEvent;
-use crate::message::{ProcessCommand, ProcessNotification};
-use crate::session::ProcessSession;
-use crate::types::{ProcessDriver, ProcessWaker};
+use crate::lifecycle::PreparedProcessOutput;
+use crate::message::{ProcessActorCommand, ProcessCommand, ProcessOutput};
+use crate::supervisor::{
+    ProcessSupervisorThread, ProcessThreadHandle, ThreadEvent, ThreadEventReceiver,
+    thread_event_channel,
+};
+use crate::types::{ExitStatus, ProcessSpec};
 
-/// Actor wrapper around a `ProcessSession` and its driver.
-///
-/// Generic over `D: ProcessDriver` so that tests can use `MockDriver` or
-/// `TestDriver` while production uses `LocalDriver`.
-pub struct ProcessActor<D: ProcessDriver> {
-    session: ProcessSession,
-    driver: D,
-    self_addr: Option<ActorAddress>,
-    /// Actions from `ProcessSession::new()`, executed in `on_start`.
-    deferred_actions: Option<Vec<ProcessAction>>,
-    /// Shared slot for the waker — filled after the actor address is known.
-    pub waker_slot: Arc<OnceLock<ProcessWaker>>,
-    /// Per-node observer that taps this process's output (command-basename
-    /// `label`) onto the node's telemetry stream. `None` when the runtime has
-    /// no observer installed.
-    output_observer: Option<Arc<dyn ProcessOutputObserver>>,
-    /// Command basename used to label this process's output to the observer.
-    label: String,
+enum ProcessActorState {
+    Spawning { stop_requested: bool },
+    Running,
+    Stopping,
+    Done(ProcessDoneState),
 }
 
-impl<D: ProcessDriver> ProcessActor<D> {
-    pub fn new(
-        session: ProcessSession,
-        driver: D,
-        initial_actions: Vec<ProcessAction>,
-        waker_slot: Arc<OnceLock<ProcessWaker>>,
-        output_observer: Option<Arc<dyn ProcessOutputObserver>>,
-        label: String,
+enum ProcessDoneState {
+    Exited(ExitStatus),
+    SpawnFailed(String),
+    SupervisorFailed(String),
+}
+
+impl ProcessDoneState {
+    fn observe(&self) {
+        match self {
+            Self::Exited(status) => {
+                let _ = *status;
+            }
+            Self::SpawnFailed(error) | Self::SupervisorFailed(error) => {
+                let _ = error.as_str();
+            }
+        }
+    }
+}
+
+pub(crate) struct ProcessActor {
+    spec: Option<ProcessSpec>,
+    output: PreparedProcessOutput,
+    sender: ExternalSender,
+    addr_slot: Arc<OnceLock<ActorAddress>>,
+    state: ProcessActorState,
+    pid: Option<u32>,
+    supervisor: Option<ProcessThreadHandle>,
+    supervisor_events: Option<ThreadEventReceiver>,
+}
+
+impl ProcessActor {
+    pub(crate) fn new(
+        spec: ProcessSpec,
+        output: PreparedProcessOutput,
+        sender: ExternalSender,
+        addr_slot: Arc<OnceLock<ActorAddress>>,
     ) -> Self {
         Self {
-            session,
-            driver,
-            self_addr: None,
-            deferred_actions: Some(initial_actions),
-            waker_slot,
-            output_observer,
-            label,
+            spec: Some(spec),
+            output,
+            sender,
+            addr_slot,
+            state: ProcessActorState::Spawning {
+                stop_requested: false,
+            },
+            pid: None,
+            supervisor: None,
+            supervisor_events: None,
         }
     }
 
-    /// Drain events from the driver, apply each to the session, and dispatch
-    /// all resulting actions.
-    fn drain_and_dispatch(&mut self, ctx: &Ctx) {
-        let events = self.driver.poll();
+    fn emit_process_output(&self, ctx: &Ctx, output: ProcessOutput) {
+        let _ = ctx.send(self.output.upstream, output.clone());
+        if let Some(mirror) = &self.output.mirror {
+            mirror.submit(&output);
+        }
+    }
+
+    fn apply_stop(&mut self, ctx: &Ctx, kill_after: Option<std::time::Duration>) {
+        let mut next_state = None;
+        let mut terminal_error = None;
+
+        match &mut self.state {
+            ProcessActorState::Spawning { stop_requested } => {
+                if *stop_requested {
+                    return;
+                }
+
+                match self
+                    .supervisor
+                    .as_ref()
+                    .expect("supervisor started before commands")
+                    .stop(kill_after)
+                {
+                    Ok(()) => *stop_requested = true,
+                    Err(error) => terminal_error = Some(error),
+                }
+            }
+            ProcessActorState::Running => {
+                match self
+                    .supervisor
+                    .as_ref()
+                    .expect("supervisor started before commands")
+                    .stop(kill_after)
+                {
+                    Ok(()) => next_state = Some(ProcessActorState::Stopping),
+                    Err(error) => terminal_error = Some(error),
+                }
+            }
+            ProcessActorState::Stopping | ProcessActorState::Done(_) => {}
+        }
+
+        if let Some(state) = next_state {
+            self.state = state;
+        }
+        if let Some(error) = terminal_error {
+            self.emit_terminal_error(ctx, error);
+        }
+    }
+
+    fn drain_supervisor_events(&mut self, ctx: &Ctx) {
+        let events = self
+            .supervisor_events
+            .as_ref()
+            .map(ThreadEventReceiver::drain)
+            .unwrap_or_default();
+
         for event in events {
-            let actions = self.session.apply(event);
-            self.dispatch_actions(ctx, actions);
+            self.handle_thread_event(ctx, event);
+            self.finish_if_safe(ctx);
         }
+        self.finish_if_safe(ctx);
     }
 
-    /// Execute actions produced by the session state machine.
-    fn dispatch_actions(&mut self, ctx: &Ctx, actions: Vec<ProcessAction>) {
-        let self_addr = self.self_addr.expect("self_addr not set");
-        for action in actions {
-            match action {
-                // Driver commands — forward to the driver
-                ProcessAction::SpawnProcess { .. }
-                | ProcessAction::WriteStdin { .. }
-                | ProcessAction::SendSignal { .. }
-                | ProcessAction::ResizePty { .. }
-                | ProcessAction::CloseStdin
-                | ProcessAction::ScheduleKillTimeout { .. } => {
-                    self.driver.execute(action);
-                }
+    fn handle_thread_event(&mut self, ctx: &Ctx, event: ThreadEvent) {
+        match event {
+            ThreadEvent::Started { pid } => {
+                let stop_requested = match &self.state {
+                    ProcessActorState::Spawning { stop_requested } => *stop_requested,
+                    ProcessActorState::Running
+                    | ProcessActorState::Stopping
+                    | ProcessActorState::Done(_) => return,
+                };
 
-                // Subscriber notifications — send to each subscriber
-                ProcessAction::NotifyStarted { subscribers } => {
-                    let notif = ProcessNotification::Started {
-                        process: self_addr,
-                        pid: self.driver.pid(),
-                    };
-                    for sub in subscribers {
-                        let _ = ctx.send(sub, notif.clone());
+                self.pid = Some(pid);
+                self.emit_process_output(ctx, ProcessOutput::Started { pid });
+                self.state = if stop_requested {
+                    ProcessActorState::Stopping
+                } else {
+                    ProcessActorState::Running
+                };
+            }
+            ThreadEvent::SpawnFailed { error } => {
+                if !matches!(self.state, ProcessActorState::Done(_)) {
+                    self.emit_process_output(
+                        ctx,
+                        ProcessOutput::SpawnFailed {
+                            error: error.clone(),
+                        },
+                    );
+                    self.state = ProcessActorState::Done(ProcessDoneState::SpawnFailed(error));
+                }
+            }
+            ThreadEvent::Exited { status } => {
+                if !matches!(self.state, ProcessActorState::Done(_)) {
+                    self.emit_process_output(ctx, ProcessOutput::Exited { status });
+                    self.state = ProcessActorState::Done(ProcessDoneState::Exited(status));
+                }
+            }
+            ThreadEvent::Error { error } => {
+                if !matches!(self.state, ProcessActorState::Done(_)) {
+                    self.emit_process_output(
+                        ctx,
+                        ProcessOutput::Error {
+                            error: error.clone(),
+                        },
+                    );
+                    self.state = ProcessActorState::Done(ProcessDoneState::SupervisorFailed(error));
+                }
+            }
+            ThreadEvent::ThreadFinished => {
+                if let Some(supervisor) = self.supervisor.as_mut() {
+                    match supervisor.join_if_finished() {
+                        Ok(_) => {}
+                        Err(_) => {
+                            if !matches!(self.state, ProcessActorState::Done(_)) {
+                                let error = "process supervisor thread failed".to_owned();
+                                self.emit_process_output(
+                                    ctx,
+                                    ProcessOutput::Error {
+                                        error: error.clone(),
+                                    },
+                                );
+                                self.state = ProcessActorState::Done(
+                                    ProcessDoneState::SupervisorFailed(error),
+                                );
+                            }
+                        }
                     }
                 }
-                ProcessAction::NotifyOutput {
-                    subscribers,
-                    data,
-                    stream,
-                } => {
-                    // Tap the node's telemetry observer before the data is moved
-                    // into the subscriber notification. Per-node, auto-attached.
-                    if let Some(obs) = &self.output_observer {
-                        obs.on_output(&self.label, matches!(stream, OutputStream::Stderr), &data);
-                    }
-                    let notif = ProcessNotification::Output {
-                        process: self_addr,
-                        data,
-                        stream,
-                    };
-                    for sub in subscribers {
-                        let _ = ctx.send(sub, notif.clone());
-                    }
-                }
-                ProcessAction::NotifyExited {
-                    subscribers,
-                    status,
-                } => {
-                    let notif = ProcessNotification::Exited {
-                        process: self_addr,
-                        status,
-                    };
-                    for sub in subscribers {
-                        let _ = ctx.send(sub, notif.clone());
-                    }
-                }
-                ProcessAction::NotifyError { subscribers, error } => {
-                    let notif = ProcessNotification::Error {
-                        process: self_addr,
-                        error,
-                    };
-                    for sub in subscribers {
-                        let _ = ctx.send(sub, notif.clone());
-                    }
-                }
-
-                // Lifecycle
-                ProcessAction::SelfTerminate => {
-                    ctx.stop_self();
-                }
+                self.supervisor = None;
+                self.supervisor_events = None;
             }
         }
     }
 
-    /// Map a `ProcessCommand` to the corresponding `ProcessEvent`.
-    fn command_to_event(cmd: ProcessCommand) -> Option<ProcessEvent> {
-        match cmd {
-            ProcessCommand::WriteStdin { data } => Some(ProcessEvent::WriteStdin { data }),
-            ProcessCommand::SendSignal { signal } => Some(ProcessEvent::SendSignal { signal }),
-            ProcessCommand::ResizePty { size } => Some(ProcessEvent::ResizePty { size }),
-            ProcessCommand::CloseStdin => Some(ProcessEvent::CloseStdin),
-            ProcessCommand::Close => Some(ProcessEvent::CloseRequested),
-            ProcessCommand::Subscribe { address } => Some(ProcessEvent::Subscribe { address }),
-            ProcessCommand::Unsubscribe { address } => Some(ProcessEvent::Unsubscribe { address }),
-            ProcessCommand::PollTick => None, // handled by drain
+    fn finish_if_safe(&mut self, ctx: &Ctx) {
+        if let ProcessActorState::Done(done) = &self.state {
+            done.observe();
+            let _ = self.pid;
+            if self.supervisor.is_none() {
+                ctx.stop_self();
+            }
         }
     }
+
+    fn emit_terminal_error(&mut self, ctx: &Ctx, error: String) {
+        if matches!(self.state, ProcessActorState::Done(_)) {
+            return;
+        }
+
+        self.emit_process_output(
+            ctx,
+            ProcessOutput::Error {
+                error: error.clone(),
+            },
+        );
+        self.state = ProcessActorState::Done(ProcessDoneState::SupervisorFailed(error));
+        ctx.stop_self();
+    }
 }
 
-impl<D: ProcessDriver + 'static> ActorInterface for ProcessActor<D> {
-    type Incoming = ProcessCommand;
+impl ActorInterface for ProcessActor {
+    type Incoming = ProcessActorCommand;
     type Response = ();
 
     fn on_start(&mut self, ctx: &Ctx) {
-        self.self_addr = Some(ctx.self_addr());
-        if let Some(actions) = self.deferred_actions.take() {
-            self.dispatch_actions(ctx, actions);
+        let sender = self.sender.clone();
+        let addr_slot = self.addr_slot.clone();
+        let (event_sink, event_receiver) = thread_event_channel(move || {
+            if let Some(addr) = addr_slot.get() {
+                let _ = sender.send_to(*addr, ProcessActorCommand::SupervisorWake);
+            }
+        });
+
+        let spec = self.spec.take().expect("process spec already taken");
+        match ProcessSupervisorThread::start(spec, event_sink) {
+            Ok(supervisor) => {
+                self.supervisor = Some(supervisor);
+                self.supervisor_events = Some(event_receiver);
+                self.drain_supervisor_events(ctx);
+            }
+            Err(err) => {
+                let error = format!("process supervisor thread failed: {err}");
+                self.emit_process_output(
+                    ctx,
+                    ProcessOutput::Error {
+                        error: error.clone(),
+                    },
+                );
+                self.state = ProcessActorState::Done(ProcessDoneState::SupervisorFailed(error));
+                ctx.stop_self();
+            }
         }
     }
 
-    fn handle(&mut self, ctx: &Ctx, msg: ProcessCommand) {
-        // Process the incoming command first — this ensures Subscribe
-        // registers before drain dispatches notifications, and keeps
-        // user commands (Close, WriteStdin) responsive.
-        if let Some(event) = Self::command_to_event(msg) {
-            let actions = self.session.apply(event);
-            self.dispatch_actions(ctx, actions);
+    fn handle(&mut self, ctx: &Ctx, msg: ProcessActorCommand) {
+        match msg {
+            ProcessActorCommand::SupervisorWake => self.drain_supervisor_events(ctx),
+            ProcessActorCommand::Command(ProcessCommand::Stop { kill_after }) => {
+                self.drain_supervisor_events(ctx);
+                self.apply_stop(ctx, kill_after);
+                self.drain_supervisor_events(ctx);
+            }
         }
+    }
 
-        // Then drain pending I/O events from background threads.
-        self.drain_and_dispatch(ctx);
+    fn on_stop(&mut self, _ctx: &Ctx) {
+        if let Some(supervisor) = &self.supervisor {
+            let _ = supervisor.shutdown_now();
+        }
     }
 }
diff --git a/crates/process/src/event.rs b/crates/process/src/event.rs
deleted file mode 100644
index 86f54b7..0000000
--- a/crates/process/src/event.rs
+++ /dev/null
@@ -1,71 +0,0 @@
-use crate::types::{ExitStatus, PtySize, Signal};
-use swactor::actor::ActorAddress;
-
-/// Events that can be applied to a ProcessSession.
-///
-/// Some events come from the driver (Started, SpawnFailed, OutputReceived, etc.),
-/// others come from the owning actor (WriteStdin, SendSignal, Subscribe, etc.).
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum ProcessEvent {
-    // --- Driver-sourced events ---
-    /// The process spawned successfully.
-    Started,
-    /// The kill timeout fired (process didn't exit after SIGTERM).
-    KillTimeout,
-    /// The process failed to spawn.
-    SpawnFailed { reason: String },
-    /// Output received on stdout or stderr.
-    OutputReceived { data: Vec<u8>, is_stderr: bool },
-    /// The process exited.
-    Exited { status: ExitStatus },
-    /// Connection to the process was lost unexpectedly.
-    ConnectionLost { reason: String },
-
-    // --- Driver acknowledgement events ---
-    /// Stdin bytes were successfully written.
-    StdinWritten { byte_count: usize },
-    /// A signal was delivered.
-    SignalSent,
-    /// The PTY was resized.
-    PtyResized,
-
-    // --- Actor-sourced events ---
-    /// Write data to the process's stdin.
-    WriteStdin { data: Vec<u8> },
-    /// Send a signal to the process.
-    SendSignal { signal: Signal },
-    /// Resize the process's PTY.
-    ResizePty { size: PtySize },
-    /// Close the process's stdin.
-    CloseStdin,
-    /// Request a graceful close of the process.
-    CloseRequested,
-    /// Subscribe an actor to process notifications.
-    Subscribe { address: ActorAddress },
-    /// Unsubscribe an actor from process notifications.
-    Unsubscribe { address: ActorAddress },
-}
-
-impl ProcessEvent {
-    /// Human-readable name for error messages.
-    pub fn name(&self) -> &'static str {
-        match self {
-            Self::Started => "Started",
-            Self::KillTimeout => "KillTimeout",
-            Self::SpawnFailed { .. } => "SpawnFailed",
-            Self::OutputReceived { .. } => "OutputReceived",
-            Self::Exited { .. } => "Exited",
-            Self::ConnectionLost { .. } => "ConnectionLost",
-            Self::StdinWritten { .. } => "StdinWritten",
-            Self::SignalSent => "SignalSent",
-            Self::PtyResized => "PtyResized",
-            Self::WriteStdin { .. } => "WriteStdin",
-            Self::SendSignal { .. } => "SendSignal",
-            Self::ResizePty { .. } => "ResizePty",
-            Self::CloseStdin => "CloseStdin",
-            Self::CloseRequested => "CloseRequested",
-            Self::Subscribe { .. } => "Subscribe",
-            Self::Unsubscribe { .. } => "Unsubscribe",
-        }
-    }
-}
diff --git a/crates/process/src/lib.rs b/crates/process/src/lib.rs
index 3140e53..171b148 100644
--- a/crates/process/src/lib.rs
+++ b/crates/process/src/lib.rs
@@ -1,28 +1,18 @@
-pub mod action;
-pub mod actor;
-pub mod event;
-pub mod local;
-pub mod message;
-pub mod mock;
+mod actor;
+mod lifecycle;
+mod message;
+mod spawn;
+mod supervisor;
+mod types;
+
 pub mod pipeline;
-pub mod session;
-pub mod spawn;
-pub mod types;
 pub mod yaml;
 
-pub use action::{OutputStream, ProcessAction};
-pub use actor::ProcessActor;
-pub use event::ProcessEvent;
-pub use local::LocalDriver;
-pub use message::{ProcessCommand, ProcessNotification};
-pub use mock::MockDriver;
+pub use lifecycle::{ProcessLifecycleObservability, ProcessOutputConfig};
+pub use message::{ProcessCommand, ProcessOutput};
 pub use pipeline::{
     JobComplete, JobDefinition, JobFailure, JobId, JobProgress, JobStatus, JobSuccess,
     LocalPipelineConfig, LocalStartJob, PipelineId, PipelineStatus,
 };
-pub use session::{ProcessSession, ProcessState};
-pub use spawn::{spawn_local_process, spawn_process};
-pub use types::{
-    EventQueue, ExitStatus, FlowControl, ProcessDriver, ProcessError, ProcessMode, ProcessSpec,
-    ProcessWaker, PtySize, Signal,
-};
+pub use spawn::{send_process_command, spawn_local_process};
+pub use types::{ExitStatus, ProcessSpec};
diff --git a/crates/process/src/lifecycle.rs b/crates/process/src/lifecycle.rs
new file mode 100644
index 0000000..c5bb966
--- /dev/null
+++ b/crates/process/src/lifecycle.rs
@@ -0,0 +1,321 @@
+use std::collections::HashSet;
+use std::sync::{Mutex, OnceLock};
+
+use datastream::{ChannelContent, DatastreamProducer, StreamId};
+use serde_json::json;
+use swactor::actor::ActorAddress;
+
+use crate::message::ProcessOutput;
+use crate::types::{ExitStatus, ProcessSpec};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ProcessLifecycleObservability {
+    Disabled,
+    DatastreamMirror,
+}
+
+#[derive(Clone)]
+pub struct ProcessOutputConfig {
+    upstream: ActorAddress,
+    observability: ProcessLifecycleObservability,
+    datastream: Option<DatastreamProducer>,
+}
+
+impl ProcessOutputConfig {
+    pub fn disabled(upstream: ActorAddress) -> Self {
+        Self {
+            upstream,
+            observability: ProcessLifecycleObservability::Disabled,
+            datastream: None,
+        }
+    }
+
+    pub fn datastream_mirror(upstream: ActorAddress, producer: DatastreamProducer) -> Self {
+        Self {
+            upstream,
+            observability: ProcessLifecycleObservability::DatastreamMirror,
+            datastream: Some(producer),
+        }
+    }
+
+    pub fn upstream(&self) -> ActorAddress {
+        self.upstream
+    }
+
+    pub fn observability(&self) -> ProcessLifecycleObservability {
+        self.observability
+    }
+}
+
+pub(crate) struct PreparedProcessOutput {
+    pub(crate) upstream: ActorAddress,
+    pub(crate) mirror: Option<LifecycleDatastreamMirror>,
+    pub(crate) _label_reservation: Option<LifecycleLabelReservation>,
+}
+
+pub(crate) struct LifecycleDatastreamMirror {
+    channel: datastream::ChannelId,
+    producer: DatastreamProducer,
+}
+
+impl LifecycleDatastreamMirror {
+    pub(crate) fn submit(&self, output: &ProcessOutput) {
+        let payload = match output {
+            ProcessOutput::Started { pid } => json!({"event": "started", "pid": pid}),
+            ProcessOutput::SpawnFailed { error } => {
+                json!({"event": "spawn_failed", "error": error})
+            }
+            ProcessOutput::Exited { status } => match status {
+                ExitStatus::Code(value) => {
+                    json!({"event": "exited", "status": {"kind": "code", "value": value}})
+                }
+                ExitStatus::Signal(value) => {
+                    json!({"event": "exited", "status": {"kind": "signal", "value": value}})
+                }
+                ExitStatus::Unknown => json!({"event": "exited", "status": {"kind": "unknown"}}),
+            },
+            ProcessOutput::Error { error } => json!({"event": "error", "error": error}),
+        };
+        let bytes = serde_json::to_vec(&payload).expect("process lifecycle record serializes");
+        let _ = self.producer.submit_bytes(self.channel, bytes);
+    }
+}
+
+pub(crate) fn prepare_process_output(
+    spec: &ProcessSpec,
+    config: ProcessOutputConfig,
+) -> Result<PreparedProcessOutput, swactor::Error> {
+    let label = derive_lifecycle_label(spec)?;
+    match config.observability {
+        ProcessLifecycleObservability::Disabled => Ok(PreparedProcessOutput {
+            upstream: config.upstream,
+            mirror: None,
+            _label_reservation: None,
+        }),
+        ProcessLifecycleObservability::DatastreamMirror => {
+            let producer = config
+                .datastream
+                .expect("datastream mirror config stores producer");
+            let reservation =
+                LifecycleLabelReservation::reserve(producer.stream_id().clone(), &label)?;
+            let channel_name = label.channel_name();
+            let channel = producer
+                .try_register_channel(
+                    channel_name,
+                    ChannelContent::JsonRecord {
+                        schema: Some("swactor_process.lifecycle.v1".to_owned()),
+                    },
+                )
+                .map_err(|err| match err {
+                    datastream::ChannelRegistrationError::ConflictingName { name } => {
+                        swactor::Error::from(format!(
+                            "conflicting datastream channel registration for {name}"
+                        ))
+                    }
+                })?;
+
+            Ok(PreparedProcessOutput {
+                upstream: config.upstream,
+                mirror: Some(LifecycleDatastreamMirror { channel, producer }),
+                _label_reservation: Some(reservation),
+            })
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub(crate) struct LifecycleLabel(String);
+
+impl LifecycleLabel {
+    pub(crate) fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub(crate) fn channel_name(&self) -> String {
+        format!("proc.{}.lifecycle", self.0)
+    }
+}
+
+pub(crate) fn derive_lifecycle_label(spec: &ProcessSpec) -> Result<LifecycleLabel, swactor::Error> {
+    let source = match spec.label.as_deref() {
+        Some(label) => label,
+        None => spec
+            .command
+            .rsplit(['/', '\\'])
+            .find(|segment| !segment.is_empty())
+            .unwrap_or(&spec.command),
+    };
+    sanitize_lifecycle_label(source)
+}
+
+fn sanitize_lifecycle_label(source: &str) -> Result<LifecycleLabel, swactor::Error> {
+    let mut sanitized = String::new();
+    let mut last_was_underscore = false;
+
+    for ch in source.trim().chars() {
+        let next = if ch.is_ascii_alphanumeric() {
+            ch.to_ascii_lowercase()
+        } else if ch == '_' || ch == '-' {
+            ch
+        } else {
+            '_'
+        };
+
+        if next == '_' {
+            if !last_was_underscore {
+                sanitized.push(next);
+            }
+            last_was_underscore = true;
+        } else {
+            sanitized.push(next);
+            last_was_underscore = false;
+        }
+    }
+
+    let sanitized = sanitized.trim_matches('_').to_owned();
+    if sanitized.is_empty() {
+        return Err(swactor::Error::from(
+            "invalid process lifecycle label: empty segment",
+        ));
+    }
+
+    Ok(LifecycleLabel(sanitized))
+}
+
+static LIFECYCLE_LABELS: OnceLock<Mutex<HashSet<(StreamId, String)>>> = OnceLock::new();
+
+pub(crate) struct LifecycleLabelReservation {
+    key: Option<(StreamId, String)>,
+}
+
+impl LifecycleLabelReservation {
+    fn reserve(stream: StreamId, label: &LifecycleLabel) -> Result<Self, swactor::Error> {
+        let key = (stream, label.as_str().to_owned());
+        let mut labels = LIFECYCLE_LABELS
+            .get_or_init(|| Mutex::new(HashSet::new()))
+            .lock()
+            .expect("process lifecycle label registry poisoned");
+        if !labels.insert(key.clone()) {
+            return Err(swactor::Error::from(format!(
+                "duplicate process lifecycle datastream channel: {} on stream {}",
+                label.channel_name(),
+                key.0
+            )));
+        }
+        Ok(Self { key: Some(key) })
+    }
+}
+
+impl Drop for LifecycleLabelReservation {
+    fn drop(&mut self) {
+        if let Some(key) = self.key.take() {
+            LIFECYCLE_LABELS
+                .get_or_init(|| Mutex::new(HashSet::new()))
+                .lock()
+                .expect("process lifecycle label registry poisoned")
+                .remove(&key);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use datastream::{DatastreamEndpoint, Lifetime, NodeId, StreamId};
+    use swactor::actor::ActorAddress;
+
+    use super::*;
+
+    fn spec(command: &str, label: Option<&str>) -> ProcessSpec {
+        ProcessSpec {
+            command: command.to_owned(),
+            args: Vec::new(),
+            env: HashMap::new(),
+            working_dir: None,
+            label: label.map(str::to_owned),
+        }
+    }
+
+    #[test]
+    fn explicit_labels_are_sanitized() {
+        assert_eq!(
+            derive_lifecycle_label(&spec("ignored", Some("trainer.0/foo")))
+                .unwrap()
+                .as_str(),
+            "trainer_0_foo"
+        );
+        assert_eq!(
+            derive_lifecycle_label(&spec("ignored", Some("  GPU Worker  ")))
+                .unwrap()
+                .as_str(),
+            "gpu_worker"
+        );
+    }
+
+    #[test]
+    fn command_basename_labels_are_sanitized() {
+        assert_eq!(
+            derive_lifecycle_label(&spec("/usr/bin/python3", None))
+                .unwrap()
+                .as_str(),
+            "python3"
+        );
+        assert_eq!(
+            derive_lifecycle_label(&spec("./bin/train.v2", None))
+                .unwrap()
+                .as_str(),
+            "train_v2"
+        );
+    }
+
+    #[test]
+    fn empty_lifecycle_labels_are_rejected() {
+        assert_eq!(
+            derive_lifecycle_label(&spec("ignored", Some("../")))
+                .unwrap_err()
+                .to_string(),
+            "invalid process lifecycle label: empty segment"
+        );
+        assert_eq!(
+            derive_lifecycle_label(&spec("", None))
+                .unwrap_err()
+                .to_string(),
+            "invalid process lifecycle label: empty segment"
+        );
+    }
+
+    #[test]
+    fn duplicate_datastream_label_reservations_are_released_on_drop() {
+        let endpoint = DatastreamEndpoint::new(StreamId::new(NodeId::new("stage2"), Lifetime(1)));
+        let upstream = ActorAddress::new_random();
+        let spec = spec("sh", Some("trainer.0/foo"));
+
+        let first = prepare_process_output(
+            &spec,
+            ProcessOutputConfig::datastream_mirror(upstream, endpoint.producer()),
+        )
+        .unwrap();
+
+        let err = match prepare_process_output(
+            &spec,
+            ProcessOutputConfig::datastream_mirror(upstream, endpoint.producer()),
+        ) {
+            Ok(_) => panic!("duplicate lifecycle label should be rejected"),
+            Err(err) => err,
+        };
+        assert_eq!(
+            err.to_string(),
+            "duplicate process lifecycle datastream channel: proc.trainer_0_foo.lifecycle on stream stage2#1"
+        );
+
+        drop(first);
+
+        let second = prepare_process_output(
+            &spec,
+            ProcessOutputConfig::datastream_mirror(upstream, endpoint.producer()),
+        )
+        .unwrap();
+        drop(second);
+    }
+}
diff --git a/crates/process/src/local/mod.rs b/crates/process/src/local/mod.rs
deleted file mode 100644
index ff160c3..0000000
--- a/crates/process/src/local/mod.rs
+++ /dev/null
@@ -1,291 +0,0 @@
-use std::io::{Read, Write};
-use std::process::{Child, ChildStdin, Command, Stdio};
-use std::sync::{Arc, OnceLock};
-use std::thread::{self, JoinHandle};
-
-use crate::action::ProcessAction;
-use crate::event::ProcessEvent;
-use crate::types::EventQueue;
-use crate::types::ProcessDriver;
-use crate::types::ProcessWaker;
-use crate::types::{ExitStatus, ProcessSpec, Signal};
-
-// ─── Signal ────────────────────────────────────────────────────────────────
-
-/// Map a `Signal` enum variant to the corresponding libc signal constant.
-fn signal_to_libc(signal: Signal) -> libc::c_int {
-    match signal {
-        Signal::Terminate => libc::SIGTERM,
-        Signal::Kill => libc::SIGKILL,
-        Signal::Hangup => libc::SIGHUP,
-        Signal::Interrupt => libc::SIGINT,
-        Signal::Other(n) => n,
-    }
-}
-
-/// Send a signal to a process by PID. Returns `Ok(())` on success.
-fn send_signal(pid: u32, signal: Signal) -> Result<(), String> {
-    let sig = signal_to_libc(signal);
-    // Safety: kill() is safe to call with any pid/signal combo;
-    // it returns -1 on error which we check.
-    let ret = unsafe { libc::kill(pid as libc::pid_t, sig) };
-    if ret == 0 {
-        Ok(())
-    } else {
-        Err(format!(
-            "kill({}, {}) failed: {}",
-            pid,
-            sig,
-            std::io::Error::last_os_error()
-        ))
-    }
-}
-
-// ─── Pipes ─────────────────────────────────────────────────────────────────
-
-/// Read from a pipe in a loop, pushing events to the queue and waking the actor.
-///
-/// Runs in a background thread. Exits when the pipe reaches EOF or errors.
-fn read_pipe(
-    mut pipe: impl Read + Send + 'static,
-    is_stderr: bool,
-    queue: EventQueue,
-    waker: Arc<OnceLock<ProcessWaker>>,
-) {
-    let mut buf = [0u8; 8192];
-    loop {
-        match pipe.read(&mut buf) {
-            Ok(0) => break, // EOF
-            Ok(n) => {
-                queue.push(ProcessEvent::OutputReceived {
-                    data: buf[..n].to_vec(),
-                    is_stderr,
-                });
-                if let Some(w) = waker.get() {
-                    w.wake();
-                }
-            }
-            Err(e) if e.kind() == std::io::ErrorKind::Interrupted => continue,
-            Err(_) => break,
-        }
-    }
-}
-
-// ─── Wait ──────────────────────────────────────────────────────────────────
-
-/// Wait for a child process to exit, then push the appropriate event.
-///
-/// Runs in a background thread. Uses `libc::waitpid` for accurate exit status.
-/// After waitpid returns, joins the pipe reader threads so all buffered
-/// stdout/stderr is drained before the `Exited` event is enqueued.
-fn wait_for_exit(
-    pid: u32,
-    reader_threads: Vec<JoinHandle<()>>,
-    queue: EventQueue,
-    waker: Arc<OnceLock<ProcessWaker>>,
-) {
-    let mut status: libc::c_int = 0;
-    let ret = unsafe { libc::waitpid(pid as libc::pid_t, &mut status, 0) };
-
-    let exit_status = if ret < 0 {
-        ExitStatus::Unknown
-    } else {
-        decode_wait_status(status)
-    };
-
-    // Wait for pipe readers to finish draining all output before signaling exit.
-    // Once the process exits, its pipe ends close, so readers will hit EOF shortly.
-    for handle in reader_threads {
-        let _ = handle.join();
-    }
-
-    queue.push(ProcessEvent::Exited {
-        status: exit_status,
-    });
-    if let Some(w) = waker.get() {
-        w.wake();
-    }
-}
-
-fn decode_wait_status(status: libc::c_int) -> ExitStatus {
-    if libc::WIFEXITED(status) {
-        ExitStatus::Code(libc::WEXITSTATUS(status))
-    } else if libc::WIFSIGNALED(status) {
-        ExitStatus::Signal(libc::WTERMSIG(status))
-    } else {
-        ExitStatus::Unknown
-    }
-}
-
-// ─── LocalDriver ───────────────────────────────────────────────────────────
-
-/// A `ProcessDriver` that spawns real OS subprocesses via `std::process::Command`.
-///
-/// Background threads read stdout/stderr and wait for process exit,
-/// pushing events into a shared `EventQueue`. The actor polls via `poll()`.
-pub struct LocalDriver {
-    queue: EventQueue,
-    waker_slot: Arc<OnceLock<ProcessWaker>>,
-    child: Option<Child>,
-    stdin: Option<ChildStdin>,
-    _wait_thread: Option<JoinHandle<()>>,
-}
-
-impl LocalDriver {
-    pub fn new(queue: EventQueue, waker_slot: Arc<OnceLock<ProcessWaker>>) -> Self {
-        Self {
-            queue,
-            waker_slot,
-            child: None,
-            stdin: None,
-            _wait_thread: None,
-        }
-    }
-
-    fn spawn_process(&mut self, spec: &ProcessSpec) {
-        let mut cmd = Command::new(&spec.command);
-        cmd.args(&spec.args);
-        for (k, v) in &spec.env {
-            cmd.env(k, v);
-        }
-        if let Some(ref dir) = spec.working_dir {
-            cmd.current_dir(dir);
-        }
-        cmd.stdin(Stdio::piped())
-            .stdout(Stdio::piped())
-            .stderr(Stdio::piped());
-
-        match cmd.spawn() {
-            Ok(mut child) => {
-                let pid = child.id();
-
-                // Take the stdin handle
-                self.stdin = child.stdin.take();
-
-                // Spawn stdout reader thread
-                let mut reader_threads = Vec::new();
-                if let Some(stdout) = child.stdout.take() {
-                    let queue = self.queue.clone();
-                    let waker = self.waker_slot.clone();
-                    reader_threads.push(
-                        thread::Builder::new()
-                            .name(format!("proc-{}-stdout", pid))
-                            .spawn(move || read_pipe(stdout, false, queue, waker))
-                            .expect("failed to spawn stdout reader"),
-                    );
-                }
-
-                // Spawn stderr reader thread
-                if let Some(stderr) = child.stderr.take() {
-                    let queue = self.queue.clone();
-                    let waker = self.waker_slot.clone();
-                    reader_threads.push(
-                        thread::Builder::new()
-                            .name(format!("proc-{}-stderr", pid))
-                            .spawn(move || read_pipe(stderr, true, queue, waker))
-                            .expect("failed to spawn stderr reader"),
-                    );
-                }
-
-                // Spawn wait thread — it joins the reader threads before pushing Exited,
-                // ensuring all output is drained before the exit event.
-                let queue = self.queue.clone();
-                let waker = self.waker_slot.clone();
-                self._wait_thread = Some(
-                    thread::Builder::new()
-                        .name(format!("proc-{}-wait", pid))
-                        .spawn(move || wait_for_exit(pid, reader_threads, queue, waker))
-                        .expect("failed to spawn wait thread"),
-                );
-
-                self.child = Some(child);
-                self.queue.push(ProcessEvent::Started);
-            }
-            Err(e) => {
-                self.queue.push(ProcessEvent::SpawnFailed {
-                    reason: e.to_string(),
-                });
-            }
-        }
-    }
-}
-
-impl ProcessDriver for LocalDriver {
-    fn execute(&mut self, action: ProcessAction) {
-        match action {
-            ProcessAction::SpawnProcess { spec } => {
-                self.spawn_process(&spec);
-            }
-            ProcessAction::WriteStdin { data } => {
-                if let Some(ref mut stdin) = self.stdin {
-                    match stdin.write_all(&data) {
-                        Ok(()) => {
-                            self.queue.push(ProcessEvent::StdinWritten {
-                                byte_count: data.len(),
-                            });
-                        }
-                        Err(e) => {
-                            self.queue.push(ProcessEvent::ConnectionLost {
-                                reason: format!("stdin write failed: {}", e),
-                            });
-                        }
-                    }
-                }
-            }
-            ProcessAction::SendSignal { signal } => {
-                if let Some(ref child) = self.child {
-                    let pid = child.id();
-                    match send_signal(pid, signal) {
-                        Ok(()) => {
-                            self.queue.push(ProcessEvent::SignalSent);
-                        }
-                        Err(reason) => {
-                            self.queue.push(ProcessEvent::ConnectionLost { reason });
-                        }
-                    }
-                }
-            }
-            ProcessAction::ResizePty { .. } => {
-                // No-op for Phase 1 (pipes only, no PTY support)
-                self.queue.push(ProcessEvent::PtyResized);
-            }
-            ProcessAction::CloseStdin => {
-                // Drop the stdin handle to close the pipe
-                self.stdin.take();
-            }
-            ProcessAction::ScheduleKillTimeout { duration } => {
-                let queue = self.queue.clone();
-                let waker = self.waker_slot.clone();
-                thread::spawn(move || {
-                    thread::sleep(duration);
-                    queue.push(ProcessEvent::KillTimeout);
-                    if let Some(w) = waker.get() {
-                        w.wake();
-                    }
-                });
-            }
-            // Notification actions are not driver commands
-            _ => {}
-        }
-    }
-
-    fn poll(&mut self) -> Vec<ProcessEvent> {
-        self.queue.drain()
-    }
-
-    fn pid(&self) -> Option<u32> {
-        self.child.as_ref().map(|c| c.id())
-    }
-}
-
-impl Drop for LocalDriver {
-    fn drop(&mut self) {
-        // Close stdin to let the process know we're done
-        self.stdin.take();
-        // Kill the process if still alive
-        if let Some(ref mut child) = self.child {
-            let _ = child.kill();
-            let _ = child.wait();
-        }
-    }
-}
diff --git a/crates/process/src/message.rs b/crates/process/src/message.rs
index d4a4d4f..d7bf448 100644
--- a/crates/process/src/message.rs
+++ b/crates/process/src/message.rs
@@ -1,58 +1,24 @@
-use swactor::actor::ActorAddress;
+use crate::types::ExitStatus;
 
-use crate::action::OutputStream;
-use crate::types::{ExitStatus, ProcessError, PtySize, Signal};
-
-/// Commands sent to a process actor.
-#[derive(Debug, Clone)]
+/// Public managed-process commands.
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ProcessCommand {
-    /// Write data to the process's stdin.
-    WriteStdin { data: Vec<u8> },
-    /// Send a signal to the process.
-    SendSignal { signal: Signal },
-    /// Resize the process's PTY.
-    ResizePty { size: PtySize },
-    /// Close the process's stdin pipe.
-    CloseStdin,
-    /// Request a graceful close of the process.
-    Close,
-    /// Subscribe to process notifications.
-    Subscribe { address: ActorAddress },
-    /// Unsubscribe from process notifications.
-    Unsubscribe { address: ActorAddress },
-    /// Internal: sent by the waker to trigger event draining.
-    #[doc(hidden)]
-    PollTick,
+    Stop {
+        kill_after: Option<std::time::Duration>,
+    },
 }
 
-/// Notifications sent from a process actor to subscribers.
-#[derive(Debug, Clone)]
-pub enum ProcessNotification {
-    /// The process started successfully.
-    ///
-    /// `pid` is `Some(u32)` when the underlying driver knows the OS
-    /// pid (real `LocalDriver`) and `None` when it doesn't
-    /// (mock drivers, future SSH-tunnel-style drivers). Telemetry hooks
-    /// can read this to attribute the subprocess in a per-node datastream.
-    Started {
-        process: ActorAddress,
-        #[doc(hidden)]
-        pid: Option<u32>,
-    },
-    /// Output was received from the process.
-    Output {
-        process: ActorAddress,
-        data: Vec<u8>,
-        stream: OutputStream,
-    },
-    /// The process exited.
-    Exited {
-        process: ActorAddress,
-        status: ExitStatus,
-    },
-    /// An error occurred.
-    Error {
-        process: ActorAddress,
-        error: ProcessError,
-    },
+/// Public managed-process outputs.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ProcessOutput {
+    Started { pid: u32 },
+    SpawnFailed { error: String },
+    Exited { status: ExitStatus },
+    Error { error: String },
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum ProcessActorCommand {
+    Command(ProcessCommand),
+    SupervisorWake,
 }
diff --git a/crates/process/src/mock.rs b/crates/process/src/mock.rs
deleted file mode 100644
index 6e14000..0000000
--- a/crates/process/src/mock.rs
+++ /dev/null
@@ -1,61 +0,0 @@
-use std::collections::VecDeque;
-
-use crate::action::ProcessAction;
-use crate::event::ProcessEvent;
-use crate::types::ProcessDriver;
-
-/// A test-oriented driver that records executed actions and lets you inject events.
-pub struct MockDriver {
-    pending_events: VecDeque<ProcessEvent>,
-    executed_actions: Vec<ProcessAction>,
-}
-
-impl MockDriver {
-    pub fn new() -> Self {
-        Self {
-            pending_events: VecDeque::new(),
-            executed_actions: Vec::new(),
-        }
-    }
-
-    /// Queue a single event to be returned by the next `poll()`.
-    pub fn inject(&mut self, event: ProcessEvent) {
-        self.pending_events.push_back(event);
-    }
-
-    /// Queue multiple events to be returned by subsequent `poll()` calls.
-    pub fn inject_many(&mut self, events: impl IntoIterator<Item = ProcessEvent>) {
-        self.pending_events.extend(events);
-    }
-
-    /// View all actions that have been executed so far.
-    pub fn executed_actions(&self) -> &[ProcessAction] {
-        &self.executed_actions
-    }
-
-    /// Take all executed actions, clearing the internal log.
-    pub fn take_executed_actions(&mut self) -> Vec<ProcessAction> {
-        std::mem::take(&mut self.executed_actions)
-    }
-
-    /// Number of events waiting to be polled.
-    pub fn pending_event_count(&self) -> usize {
-        self.pending_events.len()
-    }
-}
-
-impl Default for MockDriver {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-impl ProcessDriver for MockDriver {
-    fn execute(&mut self, action: ProcessAction) {
-        self.executed_actions.push(action);
-    }
-
-    fn poll(&mut self) -> Vec<ProcessEvent> {
-        self.pending_events.drain(..).collect()
-    }
-}
diff --git a/crates/process/src/session.rs b/crates/process/src/session.rs
deleted file mode 100644
index 09c3a35..0000000
--- a/crates/process/src/session.rs
+++ /dev/null
@@ -1,398 +0,0 @@
-use std::collections::VecDeque;
-
-use swactor::actor::ActorAddress;
-
-use crate::action::{OutputStream, ProcessAction};
-use crate::event::ProcessEvent;
-use crate::types::{ExitStatus, FlowControl, ProcessError, ProcessMode, ProcessSpec, Signal};
-
-// ─── SubscriberSet ─────────────────────────────────────────────────────────
-
-/// A deduplicated collection of subscriber addresses.
-#[derive(Debug, Clone)]
-pub(crate) struct SubscriberSet {
-    inner: Vec<ActorAddress>,
-}
-
-impl SubscriberSet {
-    pub(crate) fn new() -> Self {
-        Self { inner: Vec::new() }
-    }
-
-    /// Add an address. No-op if already present.
-    pub(crate) fn add(&mut self, address: ActorAddress) {
-        if !self.inner.contains(&address) {
-            self.inner.push(address);
-        }
-    }
-
-    /// Remove an address. No-op if not present.
-    pub(crate) fn remove(&mut self, address: &ActorAddress) {
-        self.inner.retain(|a| a != address);
-    }
-
-    /// Snapshot of current subscribers.
-    pub(crate) fn snapshot(&self) -> Vec<ActorAddress> {
-        self.inner.clone()
-    }
-
-    /// Number of subscribers.
-    pub(crate) fn count(&self) -> usize {
-        self.inner.len()
-    }
-}
-
-/// The lifecycle states of a process session.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum ProcessState {
-    Starting,
-    Running,
-    Stopping,
-    Exited,
-}
-
-impl ProcessState {
-    pub fn name(&self) -> &'static str {
-        match self {
-            Self::Starting => "Starting",
-            Self::Running => "Running",
-            Self::Stopping => "Stopping",
-            Self::Exited => "Exited",
-        }
-    }
-}
-
-/// Pure-logic state machine for managing a process lifecycle.
-///
-/// Created via `new()` which returns the session plus initial actions (SpawnProcess).
-/// Drive it forward by calling `apply(event)` which returns actions to execute.
-pub struct ProcessSession {
-    spec: ProcessSpec,
-    state: ProcessState,
-    subscribers: SubscriberSet,
-    flow: FlowControl,
-    exit_status: Option<ExitStatus>,
-    stdin_closed: bool,
-    close_requested_before_start: bool,
-    stdin_buffer: VecDeque<Vec<u8>>,
-    stdin_buffer_bytes: usize,
-}
-
-impl ProcessSession {
-    /// Create a new session. Returns the session and the initial actions to execute
-    /// (always a single `SpawnProcess` action).
-    pub fn new(spec: ProcessSpec) -> (Self, Vec<ProcessAction>) {
-        let actions = vec![ProcessAction::SpawnProcess { spec: spec.clone() }];
-        let session = Self {
-            spec,
-            state: ProcessState::Starting,
-            subscribers: SubscriberSet::new(),
-            flow: FlowControl::default(),
-            exit_status: None,
-            stdin_closed: false,
-            close_requested_before_start: false,
-            stdin_buffer: VecDeque::new(),
-            stdin_buffer_bytes: 0,
-        };
-        (session, actions)
-    }
-
-    /// Apply an event and return the resulting actions.
-    pub fn apply(&mut self, event: ProcessEvent) -> Vec<ProcessAction> {
-        // Subscribe/Unsubscribe handled in all states
-        match &event {
-            ProcessEvent::Subscribe { address } => {
-                self.subscribers.add(*address);
-                return vec![];
-            }
-            ProcessEvent::Unsubscribe { address } => {
-                self.subscribers.remove(address);
-                return vec![];
-            }
-            _ => {}
-        }
-
-        // Driver acks — silently consumed in all states
-        match &event {
-            ProcessEvent::StdinWritten { byte_count } => {
-                self.flow.pending_stdin_bytes =
-                    self.flow.pending_stdin_bytes.saturating_sub(*byte_count);
-                return self.drain_stdin_buffer();
-            }
-            ProcessEvent::SignalSent | ProcessEvent::PtyResized => {
-                return vec![];
-            }
-            _ => {}
-        }
-
-        // KillTimeout — handled in all states before per-state dispatch
-        if matches!(event, ProcessEvent::KillTimeout) {
-            return if self.state == ProcessState::Stopping {
-                vec![ProcessAction::SendSignal {
-                    signal: Signal::Kill,
-                }]
-            } else {
-                vec![]
-            };
-        }
-
-        // Dispatch to per-state handler
-        match self.state {
-            ProcessState::Starting => self.handle_starting(event),
-            ProcessState::Running => self.handle_running(event),
-            ProcessState::Stopping => self.handle_stopping(event),
-            ProcessState::Exited => self.handle_exited(event),
-        }
-    }
-
-    // --- Per-state handlers ---
-
-    fn handle_starting(&mut self, event: ProcessEvent) -> Vec<ProcessAction> {
-        match event {
-            ProcessEvent::Started => {
-                self.state = ProcessState::Running;
-                let mut actions = vec![ProcessAction::NotifyStarted {
-                    subscribers: self.subscribers.snapshot(),
-                }];
-                // If close was requested before the process started, transition to Stopping
-                if self.close_requested_before_start {
-                    self.state = ProcessState::Stopping;
-                    actions.push(ProcessAction::SendSignal {
-                        signal: Signal::Terminate,
-                    });
-                    if let Some(duration) = self.spec.kill_timeout {
-                        actions.push(ProcessAction::ScheduleKillTimeout { duration });
-                    }
-                }
-                actions
-            }
-            ProcessEvent::SpawnFailed { reason } => {
-                self.state = ProcessState::Exited;
-                vec![
-                    ProcessAction::NotifyError {
-                        subscribers: self.subscribers.snapshot(),
-                        error: ProcessError::SpawnFailed { reason },
-                    },
-                    ProcessAction::SelfTerminate,
-                ]
-            }
-            ProcessEvent::CloseRequested => {
-                self.close_requested_before_start = true;
-                vec![]
-            }
-            _ => self.invalid_state_error(&event),
-        }
-    }
-
-    fn handle_running(&mut self, event: ProcessEvent) -> Vec<ProcessAction> {
-        match event {
-            ProcessEvent::OutputReceived { data, is_stderr } => {
-                let stream = if is_stderr {
-                    OutputStream::Stderr
-                } else {
-                    OutputStream::Stdout
-                };
-                vec![ProcessAction::NotifyOutput {
-                    subscribers: self.subscribers.snapshot(),
-                    data,
-                    stream,
-                }]
-            }
-            ProcessEvent::Exited { status } => self.enter_exited(status),
-            ProcessEvent::ConnectionLost { reason } => {
-                self.state = ProcessState::Exited;
-                self.exit_status = Some(ExitStatus::Unknown);
-                self.clear_stdin_buffer();
-                vec![
-                    ProcessAction::NotifyError {
-                        subscribers: self.subscribers.snapshot(),
-                        error: ProcessError::ConnectionLost { reason },
-                    },
-                    ProcessAction::SelfTerminate,
-                ]
-            }
-            ProcessEvent::WriteStdin { data } => {
-                if self.stdin_closed {
-                    return self.notify_error(ProcessError::InvalidState {
-                        attempted: "WriteStdin",
-                        current_state: "Running (stdin closed)",
-                    });
-                }
-                // Backpressure: buffer if over limit
-                if let Some(limit) = self.spec.stdin_buffer_limit
-                    && self.flow.pending_stdin_bytes >= limit
-                {
-                    self.stdin_buffer_bytes += data.len();
-                    self.stdin_buffer.push_back(data);
-                    return vec![];
-                }
-                self.flow.pending_stdin_bytes += data.len();
-                vec![ProcessAction::WriteStdin { data }]
-            }
-            ProcessEvent::SendSignal { signal } => {
-                vec![ProcessAction::SendSignal { signal }]
-            }
-            ProcessEvent::ResizePty { size } => {
-                vec![ProcessAction::ResizePty { size }]
-            }
-            ProcessEvent::CloseStdin => {
-                if self.stdin_closed {
-                    return vec![];
-                }
-                self.stdin_closed = true;
-                self.clear_stdin_buffer();
-                vec![ProcessAction::CloseStdin]
-            }
-            ProcessEvent::CloseRequested => {
-                self.state = ProcessState::Stopping;
-                self.clear_stdin_buffer();
-                let mut actions = vec![ProcessAction::SendSignal {
-                    signal: Signal::Terminate,
-                }];
-                if let Some(duration) = self.spec.kill_timeout {
-                    actions.push(ProcessAction::ScheduleKillTimeout { duration });
-                }
-                actions
-            }
-            _ => self.invalid_state_error(&event),
-        }
-    }
-
-    fn handle_stopping(&mut self, event: ProcessEvent) -> Vec<ProcessAction> {
-        match event {
-            ProcessEvent::OutputReceived { data, is_stderr } => {
-                let stream = if is_stderr {
-                    OutputStream::Stderr
-                } else {
-                    OutputStream::Stdout
-                };
-                vec![ProcessAction::NotifyOutput {
-                    subscribers: self.subscribers.snapshot(),
-                    data,
-                    stream,
-                }]
-            }
-            ProcessEvent::Exited { status } => self.enter_exited(status),
-            ProcessEvent::ConnectionLost { reason } => {
-                self.state = ProcessState::Exited;
-                self.exit_status = Some(ExitStatus::Unknown);
-                vec![
-                    ProcessAction::NotifyError {
-                        subscribers: self.subscribers.snapshot(),
-                        error: ProcessError::ConnectionLost { reason },
-                    },
-                    ProcessAction::SelfTerminate,
-                ]
-            }
-            ProcessEvent::SendSignal { signal } => {
-                // Escalation (e.g., Kill after Terminate) is allowed in Stopping
-                vec![ProcessAction::SendSignal { signal }]
-            }
-            ProcessEvent::CloseStdin => {
-                if self.stdin_closed {
-                    return vec![];
-                }
-                self.stdin_closed = true;
-                vec![ProcessAction::CloseStdin]
-            }
-            ProcessEvent::CloseRequested => {
-                // Already stopping, no-op
-                vec![]
-            }
-            _ => self.invalid_state_error(&event),
-        }
-    }
-
-    fn handle_exited(&mut self, event: ProcessEvent) -> Vec<ProcessAction> {
-        // Everything in Exited is invalid — produce an error.
-        // (Acks and Subscribe/Unsubscribe are already handled before dispatch.)
-        self.invalid_state_error(&event)
-    }
-
-    // --- Helpers ---
-
-    fn enter_exited(&mut self, status: ExitStatus) -> Vec<ProcessAction> {
-        self.state = ProcessState::Exited;
-        self.exit_status = Some(status);
-        self.clear_stdin_buffer();
-        vec![
-            ProcessAction::NotifyExited {
-                subscribers: self.subscribers.snapshot(),
-                status,
-            },
-            ProcessAction::SelfTerminate,
-        ]
-    }
-
-    fn clear_stdin_buffer(&mut self) {
-        self.stdin_buffer.clear();
-        self.stdin_buffer_bytes = 0;
-    }
-
-    fn drain_stdin_buffer(&mut self) -> Vec<ProcessAction> {
-        let limit = match self.spec.stdin_buffer_limit {
-            Some(limit) => limit,
-            None => return vec![],
-        };
-        let mut actions = Vec::new();
-        while self.flow.pending_stdin_bytes < limit {
-            match self.stdin_buffer.pop_front() {
-                Some(data) => {
-                    self.stdin_buffer_bytes -= data.len();
-                    self.flow.pending_stdin_bytes += data.len();
-                    actions.push(ProcessAction::WriteStdin { data });
-                }
-                None => break,
-            }
-        }
-        actions
-    }
-
-    fn invalid_state_error(&self, event: &ProcessEvent) -> Vec<ProcessAction> {
-        self.notify_error(ProcessError::InvalidState {
-            attempted: event.name(),
-            current_state: self.state.name(),
-        })
-    }
-
-    fn notify_error(&self, error: ProcessError) -> Vec<ProcessAction> {
-        vec![ProcessAction::NotifyError {
-            subscribers: self.subscribers.snapshot(),
-            error,
-        }]
-    }
-
-    // --- Query methods ---
-
-    pub fn state(&self) -> ProcessState {
-        self.state
-    }
-
-    pub fn spec(&self) -> &ProcessSpec {
-        &self.spec
-    }
-
-    pub fn mode(&self) -> ProcessMode {
-        self.spec.mode
-    }
-
-    pub fn exit_status(&self) -> Option<ExitStatus> {
-        self.exit_status
-    }
-
-    pub fn flow_control(&self) -> &FlowControl {
-        &self.flow
-    }
-
-    pub fn subscriber_count(&self) -> usize {
-        self.subscribers.count()
-    }
-
-    pub fn stdin_closed(&self) -> bool {
-        self.stdin_closed
-    }
-
-    pub fn stdin_buffer_bytes(&self) -> usize {
-        self.stdin_buffer_bytes
-    }
-}
diff --git a/crates/process/src/spawn.rs b/crates/process/src/spawn.rs
index fcbfb12..6ce519e 100644
--- a/crates/process/src/spawn.rs
+++ b/crates/process/src/spawn.rs
@@ -5,89 +5,32 @@ use swactor::actor::{ActorAddress, Ctx};
 use swactor::runtime::ExternalSender;
 
 use crate::actor::ProcessActor;
-use crate::local::LocalDriver;
-use crate::message::ProcessCommand;
-use crate::session::ProcessSession;
-use crate::types::{EventQueue, ProcessDriver, ProcessSpec, ProcessWaker};
+use crate::lifecycle::{ProcessOutputConfig, prepare_process_output};
+use crate::message::{ProcessActorCommand, ProcessCommand};
+use crate::types::ProcessSpec;
 
-/// Spawn a process actor using the real `LocalDriver` (OS subprocess).
-///
-/// Creates a `ProcessActor<LocalDriver>`, spawns it in the runtime, and
-/// wires up the waker so that I/O thread events automatically wake the actor.
-///
-/// Returns the actor's address. Send `ProcessCommand` messages to control it.
+/// Spawn a process actor using the OS subprocess supervisor.
 pub fn spawn_local_process(
     ctx: &Ctx,
     sender: &ExternalSender,
     spec: ProcessSpec,
+    output: ProcessOutputConfig,
 ) -> Result<ActorAddress, Error> {
-    let waker_slot = Arc::new(OnceLock::new());
-    let queue = EventQueue::new();
-    let driver = LocalDriver::new(queue, waker_slot.clone());
-    spawn_process_inner(ctx, sender, spec, driver, waker_slot, None)
-}
-
-/// Spawn a process actor with a custom driver.
-///
-/// Useful for testing with `MockDriver` or other custom drivers while
-/// still getting the full actor integration (waker, lifecycle, etc.).
-pub fn spawn_process<D: ProcessDriver + 'static>(
-    ctx: &Ctx,
-    sender: &ExternalSender,
-    spec: ProcessSpec,
-    driver: D,
-    waker_slot: Arc<OnceLock<ProcessWaker>>,
-) -> Result<ActorAddress, Error> {
-    spawn_process_inner(ctx, sender, spec, driver, waker_slot, None)
-}
-
-/// The basename of a command path, used as the process's telemetry label.
-/// `/usr/bin/python3` → `python3`, `python` → `python`. Falls back to the whole
-/// string when there is no path separator or trailing component.
-fn command_basename(command: &str) -> String {
-    command
-        .rsplit(['/', '\\'])
-        .find(|s| !s.is_empty())
-        .unwrap_or(command)
-        .to_string()
-}
-
-fn spawn_process_inner<D: ProcessDriver + 'static>(
-    ctx: &Ctx,
-    sender: &ExternalSender,
-    spec: ProcessSpec,
-    driver: D,
-    waker_slot: Arc<OnceLock<ProcessWaker>>,
-    label_override: Option<String>,
-) -> Result<ActorAddress, Error> {
-    // Label this process's output so the node's per-runtime observer (if any)
-    // taps it onto `proc.<label>.*` automatically. Default to the command
-    // basename; a caller can override (e.g. to keep several remote shells
-    // running the same command distinguishable).
-    let label = label_override.unwrap_or_else(|| command_basename(&spec.command));
-    let observer = ctx.process_output_observer();
-    let (session, initial_actions) = ProcessSession::new(spec);
-    let actor = ProcessActor::new(
-        session,
-        driver,
-        initial_actions,
-        waker_slot.clone(),
-        observer,
-        label,
-    );
+    let prepared_output = prepare_process_output(&spec, output)?;
+    let addr_slot = Arc::new(OnceLock::new());
+    let actor = ProcessActor::new(spec, prepared_output, sender.clone(), addr_slot.clone());
     let addr = ctx.spawn(actor)?;
-
-    // Now that we have the address, fill the waker
-    let sender = sender.clone();
-    let waker = ProcessWaker::new(move || {
-        let _ = sender.send_to(addr, ProcessCommand::PollTick);
-    });
-    waker_slot
-        .set(waker.clone())
-        .expect("waker slot already set");
-
-    // Flush any events from the startup race window
-    waker.wake();
-
+    addr_slot
+        .set(addr)
+        .expect("process actor address already set");
+    let _ = sender.send_to(addr, ProcessActorCommand::SupervisorWake);
     Ok(addr)
 }
+
+pub fn send_process_command(
+    sender: &ExternalSender,
+    process: ActorAddress,
+    command: ProcessCommand,
+) -> Result<(), Error> {
+    sender.send_to(process, ProcessActorCommand::Command(command))
+}
diff --git a/crates/process/src/supervisor.rs b/crates/process/src/supervisor.rs
new file mode 100644
index 0000000..4cd9d73
--- /dev/null
+++ b/crates/process/src/supervisor.rs
@@ -0,0 +1,955 @@
+use std::io;
+use std::mem;
+use std::os::fd::RawFd;
+use std::process::{Child, Command, Stdio};
+use std::sync::Arc;
+use std::thread::{self, JoinHandle};
+use std::time::{Duration, Instant};
+
+use crossbeam_queue::SegQueue;
+
+use crate::types::{ExitStatus, ProcessSpec, Signal};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) enum ThreadCommand {
+    Stop { kill_after: Option<Duration> },
+    ShutdownNow,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) enum ThreadEvent {
+    Started { pid: u32 },
+    SpawnFailed { error: String },
+    Exited { status: ExitStatus },
+    Error { error: String },
+    ThreadFinished,
+}
+
+#[derive(Clone)]
+pub(crate) struct ThreadEventSink {
+    queue: Arc<SegQueue<ThreadEvent>>,
+    wake: Arc<dyn Fn() + Send + Sync>,
+}
+
+pub(crate) struct ThreadEventReceiver {
+    queue: Arc<SegQueue<ThreadEvent>>,
+}
+
+pub(crate) fn thread_event_channel(
+    wake: impl Fn() + Send + Sync + 'static,
+) -> (ThreadEventSink, ThreadEventReceiver) {
+    let queue = Arc::new(SegQueue::new());
+    (
+        ThreadEventSink {
+            queue: queue.clone(),
+            wake: Arc::new(wake),
+        },
+        ThreadEventReceiver { queue },
+    )
+}
+
+impl ThreadEventSink {
+    pub(crate) fn push(&self, event: ThreadEvent) {
+        self.queue.push(event);
+        (self.wake)();
+    }
+}
+
+impl ThreadEventReceiver {
+    pub(crate) fn drain(&self) -> Vec<ThreadEvent> {
+        let mut events = Vec::new();
+        while let Some(event) = self.queue.pop() {
+            events.push(event);
+        }
+        events
+    }
+}
+
+#[derive(Clone)]
+struct WakeFd(Arc<WakeFdInner>);
+
+struct WakeFdInner {
+    fd: RawFd,
+}
+
+impl WakeFd {
+    fn new() -> io::Result<Self> {
+        let fd = unsafe { libc::eventfd(0, libc::EFD_NONBLOCK | libc::EFD_CLOEXEC) };
+        if fd < 0 {
+            return Err(io::Error::last_os_error());
+        }
+
+        Ok(Self(Arc::new(WakeFdInner { fd })))
+    }
+
+    fn fd(&self) -> RawFd {
+        self.0.fd
+    }
+
+    fn wake(&self) -> io::Result<()> {
+        let value: u64 = 1;
+        let ptr = (&value as *const u64).cast::<libc::c_void>();
+        let len = mem::size_of::<u64>();
+
+        loop {
+            let written = unsafe { libc::write(self.fd(), ptr, len) };
+            if written == len as libc::ssize_t {
+                return Ok(());
+            }
+            if written < 0 {
+                let err = io::Error::last_os_error();
+                if err.kind() == io::ErrorKind::Interrupted {
+                    continue;
+                }
+                if is_would_block(&err) {
+                    return Ok(());
+                }
+                return Err(err);
+            }
+
+            return Err(io::Error::new(
+                io::ErrorKind::WriteZero,
+                "short write to process supervisor wake fd",
+            ));
+        }
+    }
+
+    fn drain(&self) -> io::Result<()> {
+        let mut value: u64 = 0;
+        let ptr = (&mut value as *mut u64).cast::<libc::c_void>();
+        let len = mem::size_of::<u64>();
+
+        loop {
+            let read = unsafe { libc::read(self.fd(), ptr, len) };
+            if read == len as libc::ssize_t {
+                continue;
+            }
+            if read < 0 {
+                let err = io::Error::last_os_error();
+                if err.kind() == io::ErrorKind::Interrupted {
+                    continue;
+                }
+                if is_would_block(&err) {
+                    return Ok(());
+                }
+                return Err(err);
+            }
+
+            return Err(io::Error::new(
+                io::ErrorKind::UnexpectedEof,
+                "short read from process supervisor wake fd",
+            ));
+        }
+    }
+}
+
+impl Drop for WakeFdInner {
+    fn drop(&mut self) {
+        let _ = unsafe { libc::close(self.fd) };
+    }
+}
+
+fn poll_command_wake(wake: &WakeFd, timeout: Duration) -> io::Result<bool> {
+    let timeout_ms = poll_timeout_ms(timeout);
+    let mut pollfd = libc::pollfd {
+        fd: wake.fd(),
+        events: libc::POLLIN,
+        revents: 0,
+    };
+
+    loop {
+        let result = unsafe { libc::poll(&mut pollfd, 1, timeout_ms) };
+        if result == 0 {
+            return Ok(false);
+        }
+        if result > 0 {
+            let revents = pollfd.revents;
+            if revents & (libc::POLLERR | libc::POLLNVAL | libc::POLLHUP) != 0 {
+                return Err(io::Error::other(format!(
+                    "process supervisor wake fd poll failed: revents={revents}"
+                )));
+            }
+            return Ok(revents & libc::POLLIN != 0);
+        }
+
+        let err = io::Error::last_os_error();
+        if err.kind() == io::ErrorKind::Interrupted {
+            continue;
+        }
+        return Err(err);
+    }
+}
+
+fn poll_timeout_ms(timeout: Duration) -> libc::c_int {
+    if timeout.is_zero() {
+        return 0;
+    }
+
+    let millis = timeout.as_millis();
+    if millis == 0 {
+        1
+    } else {
+        millis.min(libc::c_int::MAX as u128) as libc::c_int
+    }
+}
+
+fn is_would_block(err: &io::Error) -> bool {
+    matches!(
+        err.raw_os_error(),
+        Some(code) if code == libc::EAGAIN || code == libc::EWOULDBLOCK
+    )
+}
+
+pub(crate) struct ProcessThreadHandle {
+    commands: Arc<SegQueue<ThreadCommand>>,
+    wake: WakeFd,
+    join: Option<JoinHandle<()>>,
+}
+
+pub(crate) struct ProcessSupervisorThread;
+
+impl ProcessSupervisorThread {
+    pub(crate) fn start(
+        spec: ProcessSpec,
+        events: ThreadEventSink,
+    ) -> Result<ProcessThreadHandle, swactor::Error> {
+        let commands = Arc::new(SegQueue::new());
+        let wake = WakeFd::new().map_err(|err| {
+            swactor::Error::from(format!(
+                "failed to create process supervisor wake fd: {err}"
+            ))
+        })?;
+
+        let thread_commands = commands.clone();
+        let thread_wake = wake.clone();
+        let join = thread::Builder::new()
+            .name("swactor-process-supervisor".to_owned())
+            .spawn(move || supervisor_thread_main(spec, events, thread_commands, thread_wake))
+            .map_err(|err| {
+                swactor::Error::from(format!("failed to start process supervisor thread: {err}"))
+            })?;
+
+        Ok(ProcessThreadHandle {
+            commands,
+            wake,
+            join: Some(join),
+        })
+    }
+}
+
+impl ProcessThreadHandle {
+    pub(crate) fn send(&self, command: ThreadCommand) -> Result<(), String> {
+        self.commands.push(command);
+        self.wake
+            .wake()
+            .map_err(|err| format!("failed to wake process supervisor: {err}"))
+    }
+
+    pub(crate) fn stop(&self, kill_after: Option<Duration>) -> Result<(), String> {
+        self.send(ThreadCommand::Stop { kill_after })
+    }
+
+    pub(crate) fn shutdown_now(&self) -> Result<(), String> {
+        self.send(ThreadCommand::ShutdownNow)
+    }
+
+    pub(crate) fn is_finished(&self) -> bool {
+        match &self.join {
+            Some(join) => join.is_finished(),
+            None => true,
+        }
+    }
+
+    pub(crate) fn join_if_finished(&mut self) -> Result<bool, String> {
+        if !self.is_finished() {
+            return Ok(false);
+        }
+
+        if let Some(join) = self.join.take() {
+            join.join()
+                .map_err(|_| "process supervisor thread panicked".to_owned())?;
+        }
+
+        Ok(true)
+    }
+}
+
+impl Drop for ProcessThreadHandle {
+    fn drop(&mut self) {
+        let _ = self.shutdown_now();
+        let _ = self.join_if_finished();
+    }
+}
+
+const WAITPID_POLL_INTERVAL: Duration = Duration::from_millis(10);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum SupervisorState {
+    Spawning,
+    Running,
+    Stopping,
+    Done,
+}
+
+enum CommandOutcome {
+    Continue,
+    Exited(ExitStatus),
+    Error(String),
+}
+
+fn supervisor_thread_main(
+    spec: ProcessSpec,
+    events: ThreadEventSink,
+    commands: Arc<SegQueue<ThreadCommand>>,
+    wake: WakeFd,
+) {
+    let mut state = SupervisorState::Spawning;
+    let mut child: Option<Child>;
+    let pid: Option<u32>;
+    let mut kill_deadline: Option<Instant> = None;
+    let mut kill_sent = false;
+    debug_assert!(matches!(state, SupervisorState::Spawning));
+
+    let mut cmd = Command::new(&spec.command);
+    cmd.args(&spec.args);
+    for (key, value) in &spec.env {
+        cmd.env(key, value);
+    }
+    if let Some(dir) = &spec.working_dir {
+        cmd.current_dir(dir);
+    }
+    cmd.stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null());
+
+    match cmd.spawn() {
+        Ok(spawned_child) => {
+            let child_pid = spawned_child.id();
+            pid = Some(child_pid);
+            child = Some(spawned_child);
+            events.push(ThreadEvent::Started { pid: child_pid });
+            state = SupervisorState::Running;
+
+            match drain_queued_commands(
+                child_pid,
+                &commands,
+                &mut state,
+                &mut kill_deadline,
+                &mut kill_sent,
+            ) {
+                CommandOutcome::Continue => {}
+                CommandOutcome::Exited(status) => {
+                    finish_with_exit(&events, &mut state, &mut child, status);
+                    return;
+                }
+                CommandOutcome::Error(error) => {
+                    finish_with_error(&events, &mut state, &mut child, error);
+                    return;
+                }
+            }
+        }
+        Err(err) => {
+            events.push(ThreadEvent::SpawnFailed {
+                error: err.to_string(),
+            });
+            events.push(ThreadEvent::ThreadFinished);
+            return;
+        }
+    }
+
+    let child_pid = pid.expect("supervisor pid stored after successful spawn");
+    loop {
+        let timeout = command_poll_timeout(kill_deadline);
+        match poll_command_wake(&wake, timeout) {
+            Ok(true) => {
+                if let Err(err) = wake.drain() {
+                    finish_with_error(
+                        &events,
+                        &mut state,
+                        &mut child,
+                        format!("process supervisor command wake failed: {err}"),
+                    );
+                    return;
+                }
+
+                match drain_queued_commands(
+                    child_pid,
+                    &commands,
+                    &mut state,
+                    &mut kill_deadline,
+                    &mut kill_sent,
+                ) {
+                    CommandOutcome::Continue => {}
+                    CommandOutcome::Exited(status) => {
+                        finish_with_exit(&events, &mut state, &mut child, status);
+                        return;
+                    }
+                    CommandOutcome::Error(error) => {
+                        finish_with_error(&events, &mut state, &mut child, error);
+                        return;
+                    }
+                }
+            }
+            Ok(false) => {}
+            Err(err) => {
+                finish_with_error(
+                    &events,
+                    &mut state,
+                    &mut child,
+                    format!("process supervisor command wake failed: {err}"),
+                );
+                return;
+            }
+        }
+
+        match try_wait_pid(child_pid) {
+            Ok(Some(status)) => {
+                finish_with_exit(&events, &mut state, &mut child, status);
+                return;
+            }
+            Ok(None) => {}
+            Err(error) => {
+                finish_with_error(&events, &mut state, &mut child, error);
+                return;
+            }
+        }
+
+        if kill_deadline.is_some_and(|deadline| deadline <= Instant::now()) && !kill_sent {
+            match send_kill_or_observe_exit(child_pid) {
+                CommandOutcome::Continue => {
+                    kill_sent = true;
+                    kill_deadline = None;
+                    continue;
+                }
+                CommandOutcome::Exited(status) => {
+                    finish_with_exit(&events, &mut state, &mut child, status);
+                    return;
+                }
+                CommandOutcome::Error(error) => {
+                    finish_with_error(&events, &mut state, &mut child, error);
+                    return;
+                }
+            }
+        }
+    }
+}
+
+fn command_poll_timeout(kill_deadline: Option<Instant>) -> Duration {
+    let Some(deadline) = kill_deadline else {
+        return WAITPID_POLL_INTERVAL;
+    };
+
+    let now = Instant::now();
+    if deadline <= now {
+        Duration::ZERO
+    } else {
+        (deadline - now).min(WAITPID_POLL_INTERVAL)
+    }
+}
+
+fn drain_queued_commands(
+    pid: u32,
+    commands: &SegQueue<ThreadCommand>,
+    state: &mut SupervisorState,
+    kill_deadline: &mut Option<Instant>,
+    kill_sent: &mut bool,
+) -> CommandOutcome {
+    while let Some(command) = commands.pop() {
+        match apply_thread_command(pid, command, state, kill_deadline, kill_sent) {
+            CommandOutcome::Continue => {}
+            outcome => return outcome,
+        }
+    }
+
+    CommandOutcome::Continue
+}
+
+fn apply_thread_command(
+    pid: u32,
+    command: ThreadCommand,
+    state: &mut SupervisorState,
+    kill_deadline: &mut Option<Instant>,
+    kill_sent: &mut bool,
+) -> CommandOutcome {
+    match command {
+        ThreadCommand::Stop { kill_after } => match state {
+            SupervisorState::Running => match send_terminate_or_observe_exit(pid) {
+                CommandOutcome::Continue => {
+                    if let Some(duration) = kill_after {
+                        *kill_deadline = Some(Instant::now() + duration);
+                    } else {
+                        *kill_deadline = None;
+                    }
+                    *state = SupervisorState::Stopping;
+                    CommandOutcome::Continue
+                }
+                outcome => outcome,
+            },
+            SupervisorState::Spawning | SupervisorState::Stopping | SupervisorState::Done => {
+                CommandOutcome::Continue
+            }
+        },
+        ThreadCommand::ShutdownNow => match state {
+            SupervisorState::Done => CommandOutcome::Continue,
+            SupervisorState::Spawning | SupervisorState::Running | SupervisorState::Stopping => {
+                *state = SupervisorState::Stopping;
+                *kill_deadline = None;
+                match send_terminate_or_observe_exit(pid) {
+                    CommandOutcome::Continue => match try_wait_pid(pid) {
+                        Ok(Some(status)) => CommandOutcome::Exited(status),
+                        Ok(None) => match send_kill_or_observe_exit(pid) {
+                            CommandOutcome::Continue => {
+                                *kill_sent = true;
+                                CommandOutcome::Continue
+                            }
+                            outcome => outcome,
+                        },
+                        Err(error) => CommandOutcome::Error(error),
+                    },
+                    outcome => outcome,
+                }
+            }
+        },
+    }
+}
+
+fn send_terminate_or_observe_exit(pid: u32) -> CommandOutcome {
+    match send_signal(pid, Signal::Terminate) {
+        Ok(()) => CommandOutcome::Continue,
+        Err(kill_error) => match try_wait_pid(pid) {
+            Ok(Some(status)) => CommandOutcome::Exited(status),
+            Ok(None) => {
+                CommandOutcome::Error(format!("failed to terminate process {pid}: {kill_error}"))
+            }
+            Err(error) => CommandOutcome::Error(error),
+        },
+    }
+}
+
+fn send_kill_or_observe_exit(pid: u32) -> CommandOutcome {
+    match send_signal(pid, Signal::Kill) {
+        Ok(()) => CommandOutcome::Continue,
+        Err(kill_error) => match try_wait_pid(pid) {
+            Ok(Some(status)) => CommandOutcome::Exited(status),
+            Ok(None) => {
+                CommandOutcome::Error(format!("failed to kill process {pid}: {kill_error}"))
+            }
+            Err(error) => CommandOutcome::Error(error),
+        },
+    }
+}
+
+fn finish_with_exit(
+    events: &ThreadEventSink,
+    state: &mut SupervisorState,
+    child: &mut Option<Child>,
+    status: ExitStatus,
+) {
+    *state = SupervisorState::Done;
+    debug_assert!(matches!(*state, SupervisorState::Done));
+    let _ = child.take();
+    events.push(ThreadEvent::Exited { status });
+    events.push(ThreadEvent::ThreadFinished);
+}
+
+fn finish_with_error(
+    events: &ThreadEventSink,
+    state: &mut SupervisorState,
+    child: &mut Option<Child>,
+    error: String,
+) {
+    *state = SupervisorState::Done;
+    debug_assert!(matches!(*state, SupervisorState::Done));
+    let _ = child.take();
+    events.push(ThreadEvent::Error { error });
+    events.push(ThreadEvent::ThreadFinished);
+}
+
+fn signal_to_libc(signal: Signal) -> libc::c_int {
+    match signal {
+        Signal::Terminate => libc::SIGTERM,
+        Signal::Kill => libc::SIGKILL,
+    }
+}
+
+fn send_signal(pid: u32, signal: Signal) -> Result<(), String> {
+    let sig = signal_to_libc(signal);
+    let ret = unsafe { libc::kill(pid as libc::pid_t, sig) };
+    if ret == 0 {
+        Ok(())
+    } else {
+        Err(format!(
+            "kill({}, {}) failed: {}",
+            pid,
+            sig,
+            std::io::Error::last_os_error()
+        ))
+    }
+}
+
+fn decode_wait_status(status: libc::c_int) -> ExitStatus {
+    if libc::WIFEXITED(status) {
+        ExitStatus::Code(libc::WEXITSTATUS(status))
+    } else if libc::WIFSIGNALED(status) {
+        ExitStatus::Signal(libc::WTERMSIG(status))
+    } else {
+        ExitStatus::Unknown
+    }
+}
+
+fn try_wait_pid(pid: u32) -> Result<Option<ExitStatus>, String> {
+    loop {
+        let mut status: libc::c_int = 0;
+        let result = unsafe { libc::waitpid(pid as libc::pid_t, &mut status, libc::WNOHANG) };
+
+        if result == 0 {
+            return Ok(None);
+        }
+        if result == pid as libc::pid_t {
+            return Ok(Some(decode_wait_status(status)));
+        }
+        if result > 0 {
+            return Ok(Some(ExitStatus::Unknown));
+        }
+
+        let err = std::io::Error::last_os_error();
+        if err.kind() == io::ErrorKind::Interrupted {
+            continue;
+        }
+        return Err(format!("waitpid({pid}) failed: {err}"));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use std::collections::HashMap;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    fn spec(command: &str, args: Vec<&str>) -> ProcessSpec {
+        ProcessSpec {
+            command: command.to_owned(),
+            args: args.into_iter().map(str::to_owned).collect(),
+            env: HashMap::new(),
+            working_dir: None,
+            label: None,
+        }
+    }
+
+    fn shell_spec(script: &str) -> ProcessSpec {
+        spec("sh", vec!["-c", script])
+    }
+
+    fn collect_until_finished(
+        receiver: &ThreadEventReceiver,
+        timeout: Duration,
+    ) -> Vec<ThreadEvent> {
+        let deadline = Instant::now() + timeout;
+        let mut events = Vec::new();
+
+        while Instant::now() < deadline {
+            events.extend(receiver.drain());
+            if matches!(events.last(), Some(ThreadEvent::ThreadFinished)) {
+                return events;
+            }
+            thread::sleep(Duration::from_millis(5));
+        }
+
+        events.extend(receiver.drain());
+        events
+    }
+
+    fn join_finished(handle: &mut ProcessThreadHandle) {
+        let deadline = Instant::now() + Duration::from_secs(2);
+        loop {
+            if handle
+                .join_if_finished()
+                .expect("supervisor thread should join")
+            {
+                return;
+            }
+            assert!(
+                Instant::now() < deadline,
+                "supervisor thread did not finish before join timeout"
+            );
+            thread::sleep(Duration::from_millis(5));
+        }
+    }
+
+    #[test]
+    fn thread_command_and_event_shapes_match_target_contract() {
+        let stop_with_deadline = ThreadCommand::Stop {
+            kill_after: Some(Duration::from_millis(10)),
+        };
+        assert_eq!(
+            stop_with_deadline,
+            ThreadCommand::Stop {
+                kill_after: Some(Duration::from_millis(10))
+            }
+        );
+        match stop_with_deadline {
+            ThreadCommand::Stop {
+                kill_after: Some(duration),
+            } => assert_eq!(duration, Duration::from_millis(10)),
+            _ => panic!("expected stop command with deadline"),
+        }
+
+        let stop_without_deadline = ThreadCommand::Stop { kill_after: None };
+        assert_eq!(
+            stop_without_deadline,
+            ThreadCommand::Stop { kill_after: None }
+        );
+        match stop_without_deadline {
+            ThreadCommand::Stop { kill_after: None } => {}
+            _ => panic!("expected stop command without deadline"),
+        }
+
+        assert_eq!(ThreadCommand::ShutdownNow, ThreadCommand::ShutdownNow);
+        match ThreadCommand::ShutdownNow {
+            ThreadCommand::ShutdownNow => {}
+            _ => panic!("expected shutdown command"),
+        }
+
+        let started = ThreadEvent::Started { pid: 42 };
+        assert_eq!(started, ThreadEvent::Started { pid: 42 });
+        match started {
+            ThreadEvent::Started { pid } => assert_eq!(pid, 42),
+            _ => panic!("expected started event"),
+        }
+
+        let spawn_failed = ThreadEvent::SpawnFailed {
+            error: "spawn failed".to_owned(),
+        };
+        assert_eq!(
+            spawn_failed,
+            ThreadEvent::SpawnFailed {
+                error: "spawn failed".to_owned()
+            }
+        );
+        match spawn_failed {
+            ThreadEvent::SpawnFailed { error } => assert_eq!(error, "spawn failed"),
+            _ => panic!("expected spawn failed event"),
+        }
+
+        let exited = ThreadEvent::Exited {
+            status: ExitStatus::Code(7),
+        };
+        assert_eq!(
+            exited,
+            ThreadEvent::Exited {
+                status: ExitStatus::Code(7)
+            }
+        );
+        match exited {
+            ThreadEvent::Exited { status } => assert_eq!(status, ExitStatus::Code(7)),
+            _ => panic!("expected exited event"),
+        }
+
+        let error = ThreadEvent::Error {
+            error: "lost".to_owned(),
+        };
+        assert_eq!(
+            error,
+            ThreadEvent::Error {
+                error: "lost".to_owned()
+            }
+        );
+        match error {
+            ThreadEvent::Error { error } => assert_eq!(error, "lost"),
+            _ => panic!("expected error event"),
+        }
+
+        assert_eq!(ThreadEvent::ThreadFinished, ThreadEvent::ThreadFinished);
+        match ThreadEvent::ThreadFinished {
+            ThreadEvent::ThreadFinished => {}
+            _ => panic!("expected thread finished event"),
+        }
+    }
+
+    #[test]
+    fn thread_event_sink_enqueues_then_wakes() {
+        let wake_count = Arc::new(AtomicUsize::new(0));
+        let wake_count_for_callback = wake_count.clone();
+        let (sink, receiver) = thread_event_channel(move || {
+            wake_count_for_callback.fetch_add(1, Ordering::SeqCst);
+        });
+
+        sink.push(ThreadEvent::Started { pid: 1 });
+        sink.push(ThreadEvent::Exited {
+            status: ExitStatus::Code(0),
+        });
+
+        assert_eq!(wake_count.load(Ordering::SeqCst), 2);
+        assert_eq!(
+            receiver.drain(),
+            vec![
+                ThreadEvent::Started { pid: 1 },
+                ThreadEvent::Exited {
+                    status: ExitStatus::Code(0)
+                }
+            ]
+        );
+        assert!(receiver.drain().is_empty());
+    }
+
+    #[test]
+    fn process_thread_handle_queues_commands_and_wakes_supervisor() {
+        let commands = Arc::new(SegQueue::new());
+        let wake = WakeFd::new().expect("wake fd should be created");
+        let handle = ProcessThreadHandle {
+            commands: commands.clone(),
+            wake: wake.clone(),
+            join: None,
+        };
+
+        handle
+            .send(ThreadCommand::Stop {
+                kill_after: Some(Duration::from_millis(25)),
+            })
+            .expect("stop command should queue");
+        handle
+            .send(ThreadCommand::ShutdownNow)
+            .expect("shutdown command should queue");
+
+        assert!(
+            poll_command_wake(&wake, Duration::ZERO).expect("wake poll should succeed"),
+            "wake fd should be readable after queued commands"
+        );
+        wake.drain().expect("wake fd should drain");
+        assert_eq!(
+            commands.pop(),
+            Some(ThreadCommand::Stop {
+                kill_after: Some(Duration::from_millis(25))
+            })
+        );
+        assert_eq!(commands.pop(), Some(ThreadCommand::ShutdownNow));
+        assert_eq!(commands.pop(), None);
+    }
+
+    #[test]
+    fn supervisor_reports_started_exited_and_finished() {
+        let (sink, receiver) = thread_event_channel(|| {});
+        let mut handle = ProcessSupervisorThread::start(shell_spec("exit 7"), sink)
+            .expect("supervisor should start");
+
+        let events = collect_until_finished(&receiver, Duration::from_secs(2));
+        join_finished(&mut handle);
+
+        assert_eq!(events.len(), 3);
+        assert!(matches!(
+            events.first(),
+            Some(ThreadEvent::Started { pid }) if *pid > 0
+        ));
+        assert_eq!(
+            events.get(1),
+            Some(&ThreadEvent::Exited {
+                status: ExitStatus::Code(7)
+            })
+        );
+        assert_eq!(events.last(), Some(&ThreadEvent::ThreadFinished));
+    }
+
+    #[test]
+    fn supervisor_reports_spawn_failed_and_finished() {
+        let (sink, receiver) = thread_event_channel(|| {});
+        let mut handle =
+            ProcessSupervisorThread::start(spec("/definitely/not/a/real/binary", vec![]), sink)
+                .expect("supervisor should start");
+
+        let events = collect_until_finished(&receiver, Duration::from_secs(2));
+        join_finished(&mut handle);
+
+        assert_eq!(events.len(), 2);
+        assert!(matches!(
+            events.first(),
+            Some(ThreadEvent::SpawnFailed { error }) if !error.is_empty()
+        ));
+        assert_eq!(events.last(), Some(&ThreadEvent::ThreadFinished));
+        assert!(!events.iter().any(|event| {
+            matches!(
+                event,
+                ThreadEvent::Started { .. }
+                    | ThreadEvent::Exited { .. }
+                    | ThreadEvent::Error { .. }
+            )
+        }));
+    }
+
+    #[test]
+    fn supervisor_uses_null_stdio_and_reports_only_lifecycle() {
+        let (sink, receiver) = thread_event_channel(|| {});
+        let mut handle = ProcessSupervisorThread::start(
+            shell_spec("echo stdout; echo stderr >&2; exit 0"),
+            sink,
+        )
+        .expect("supervisor should start");
+
+        let events = collect_until_finished(&receiver, Duration::from_secs(2));
+        join_finished(&mut handle);
+
+        assert_eq!(events.len(), 3);
+        assert!(matches!(
+            events.first(),
+            Some(ThreadEvent::Started { pid }) if *pid > 0
+        ));
+        assert_eq!(
+            events.get(1),
+            Some(&ThreadEvent::Exited {
+                status: ExitStatus::Code(0)
+            })
+        );
+        assert_eq!(events.last(), Some(&ThreadEvent::ThreadFinished));
+    }
+
+    #[test]
+    fn supervisor_stop_escalates_to_kill_after_deadline() {
+        let (sink, receiver) = thread_event_channel(|| {});
+        let mut handle = ProcessSupervisorThread::start(
+            shell_spec("trap '' TERM; while true; do sleep 1; done"),
+            sink,
+        )
+        .expect("supervisor should start");
+        let deadline = Instant::now() + Duration::from_secs(3);
+        let mut events = Vec::new();
+        let mut stop_sent = false;
+
+        while Instant::now() < deadline {
+            events.extend(receiver.drain());
+            if !stop_sent
+                && events
+                    .iter()
+                    .any(|event| matches!(event, ThreadEvent::Started { pid } if *pid > 0))
+            {
+                handle
+                    .stop(Some(Duration::from_millis(20)))
+                    .expect("stop command should queue");
+                stop_sent = true;
+            }
+            if matches!(events.last(), Some(ThreadEvent::ThreadFinished)) {
+                break;
+            }
+            thread::sleep(Duration::from_millis(5));
+        }
+
+        if !matches!(events.last(), Some(ThreadEvent::ThreadFinished)) {
+            let _ = handle.shutdown_now();
+            events.extend(collect_until_finished(&receiver, Duration::from_secs(2)));
+        }
+        join_finished(&mut handle);
+
+        assert!(
+            stop_sent,
+            "supervisor did not report Started before timeout"
+        );
+        assert_eq!(events.last(), Some(&ThreadEvent::ThreadFinished));
+        assert!(events.iter().any(|event| {
+            matches!(
+                event,
+                ThreadEvent::Exited {
+                    status: ExitStatus::Signal(9)
+                }
+            )
+        }));
+    }
+}
diff --git a/crates/process/src/types.rs b/crates/process/src/types.rs
index 6dcc152..34cceb3 100644
--- a/crates/process/src/types.rs
+++ b/crates/process/src/types.rs
@@ -1,41 +1,12 @@
 use std::collections::HashMap;
-use std::sync::Arc;
-use std::time::Duration;
 
-use crossbeam_queue::SegQueue;
-
-use crate::action::ProcessAction;
-use crate::event::ProcessEvent;
-
-/// Describes how to spawn a process.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ProcessSpec {
     pub command: String,
     pub args: Vec<String>,
     pub env: HashMap<String, String>,
-    pub working_dir: Option<String>,
-    pub mode: ProcessMode,
-    pub initial_pty_size: Option<PtySize>,
-    /// If set, escalate to SIGKILL after this duration if the process hasn't exited
-    /// after SIGTERM. None = no escalation.
-    pub kill_timeout: Option<Duration>,
-    /// If set, buffer stdin writes when pending bytes exceed this limit.
-    /// None = unlimited (current behavior).
-    pub stdin_buffer_limit: Option<usize>,
-}
-
-/// Whether the process is interactive (PTY) or automated (pipes).
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum ProcessMode {
-    Interactive,
-    Automated,
-}
-
-/// Dimensions of a pseudo-terminal.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub struct PtySize {
-    pub cols: u16,
-    pub rows: u16,
+    pub working_dir: Option<std::path::PathBuf>,
+    pub label: Option<String>,
 }
 
 /// How a process exited.
@@ -46,128 +17,8 @@ pub enum ExitStatus {
     Unknown,
 }
 
-/// Signals that can be sent to a process.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum Signal {
+pub(crate) enum Signal {
     Terminate,
     Kill,
-    Hangup,
-    Interrupt,
-    Other(i32),
-}
-
-/// Errors produced by the process session.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum ProcessError {
-    SpawnFailed {
-        reason: String,
-    },
-    ConnectionLost {
-        reason: String,
-    },
-    InvalidState {
-        attempted: &'static str,
-        current_state: &'static str,
-    },
-}
-
-/// Passive tracking of stdin backpressure.
-#[derive(Debug, Clone, PartialEq, Eq, Default)]
-pub struct FlowControl {
-    pub pending_stdin_bytes: usize,
-}
-
-// ─── ProcessDriver ─────────────────────────────────────────────────────────
-
-/// Abstraction over the mechanism that actually runs a process.
-///
-/// Implementations translate `ProcessAction` commands into real I/O (or mock I/O)
-/// and produce `ProcessEvent`s by polling for state changes.
-pub trait ProcessDriver: Send {
-    /// Execute an action (spawn, write stdin, send signal, etc.).
-    fn execute(&mut self, action: ProcessAction);
-
-    /// Poll for new events from the underlying process.
-    fn poll(&mut self) -> Vec<ProcessEvent>;
-
-    /// PID of the underlying OS process when the driver knows one.
-    ///
-    /// Returns `None` before the child has spawned, after it has been
-    /// reaped, or for drivers that do not run an OS process (mocks,
-    /// SSH-tunnel drivers that wrap a remote shell). The default
-    /// impl returns `None` so existing drivers compile unchanged.
-    ///
-    /// Read by [`crate::actor::ProcessActor`] when it builds the
-    /// outbound `ProcessNotification::Started { pid }` — this is the
-    /// channel observability hooks use to learn the subprocess's PID
-    /// without coupling to a particular driver implementation
-    /// (`N3_OBSERVABILITY_UPGRADE_SPEC.md` §4 wiring contract).
-    fn pid(&self) -> Option<u32> {
-        None
-    }
-}
-
-// ─── ProcessWaker ──────────────────────────────────────────────────────────
-
-/// A handle that I/O threads use to wake the owning actor.
-///
-/// Constructed with a closure that sends a `ProcessCommand::PollTick`
-/// to the actor via `ExternalSender`. Thread-safe and cloneable.
-#[derive(Clone)]
-pub struct ProcessWaker(Arc<dyn Fn() + Send + Sync>);
-
-impl std::fmt::Debug for ProcessWaker {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("ProcessWaker").finish_non_exhaustive()
-    }
-}
-
-impl ProcessWaker {
-    pub fn new(f: impl Fn() + Send + Sync + 'static) -> Self {
-        Self(Arc::new(f))
-    }
-
-    /// Wake the owning actor so it drains pending events.
-    pub fn wake(&self) {
-        (self.0)();
-    }
-}
-
-// ─── EventQueue ────────────────────────────────────────────────────────────
-
-/// Thread-safe queue for buffering process events from I/O threads.
-///
-/// Cloneable via inner `Arc` — I/O threads push events, the driver's
-/// `poll()` drains them.
-#[derive(Clone)]
-pub struct EventQueue {
-    inner: Arc<SegQueue<ProcessEvent>>,
-}
-
-impl EventQueue {
-    pub fn new() -> Self {
-        Self {
-            inner: Arc::new(SegQueue::new()),
-        }
-    }
-
-    /// Push an event (called from I/O threads).
-    pub fn push(&self, event: ProcessEvent) {
-        self.inner.push(event);
-    }
-
-    /// Drain all pending events (called from driver's `poll()`).
-    pub fn drain(&self) -> Vec<ProcessEvent> {
-        let mut events = Vec::new();
-        while let Some(event) = self.inner.pop() {
-            events.push(event);
-        }
-        events
-    }
-}
-
-impl Default for EventQueue {
-    fn default() -> Self {
-        Self::new()
-    }
 }
diff --git a/crates/process/tests/actor_scenarios.rs b/crates/process/tests/actor_scenarios.rs
deleted file mode 100644
index 1ed7cc1..0000000
--- a/crates/process/tests/actor_scenarios.rs
+++ /dev/null
@@ -1,570 +0,0 @@
-//! Layer 3 — Actor integration tests.
-//!
-//! Uses a TestDriver backed by a shared EventQueue so tests can inject
-//! events and observe actions without real OS processes.
-
-use std::collections::HashMap;
-use std::sync::{Arc, Mutex, OnceLock};
-
-use swactor::actor::{ActorAddress, ActorInterface, Ctx};
-use swactor::runtime::{Inbox, Runtime, RuntimeConfig};
-
-use swactor_process::*;
-
-// ── TestDriver ──────────────────────────────────────────────────────────────
-
-/// Shared harness for injecting events and inspecting driver actions.
-#[derive(Clone)]
-struct TestHarness {
-    queue: EventQueue,
-    actions: Arc<Mutex<Vec<ProcessAction>>>,
-}
-
-impl TestHarness {
-    fn new() -> Self {
-        Self {
-            queue: EventQueue::new(),
-            actions: Arc::new(Mutex::new(Vec::new())),
-        }
-    }
-
-    fn inject(&self, event: ProcessEvent) {
-        self.queue.push(event);
-    }
-
-    fn take_actions(&self) -> Vec<ProcessAction> {
-        std::mem::take(&mut self.actions.lock().unwrap())
-    }
-}
-
-/// A ProcessDriver that records actions and drains from a shared queue.
-struct TestDriver {
-    queue: EventQueue,
-    actions: Arc<Mutex<Vec<ProcessAction>>>,
-}
-
-impl TestDriver {
-    fn from_harness(harness: &TestHarness) -> Self {
-        Self {
-            queue: harness.queue.clone(),
-            actions: harness.actions.clone(),
-        }
-    }
-}
-
-impl ProcessDriver for TestDriver {
-    fn execute(&mut self, action: ProcessAction) {
-        self.actions.lock().unwrap().push(action);
-    }
-
-    fn poll(&mut self) -> Vec<ProcessEvent> {
-        self.queue.drain()
-    }
-}
-
-// ── Helpers ─────────────────────────────────────────────────────────────────
-
-fn automated_spec() -> ProcessSpec {
-    ProcessSpec {
-        command: "echo".into(),
-        args: vec!["hello".into()],
-        env: HashMap::new(),
-        working_dir: None,
-        mode: ProcessMode::Automated,
-        initial_pty_size: None,
-        kill_timeout: None,
-        stdin_buffer_limit: None,
-    }
-}
-
-fn setup() -> (Runtime, ExternalSender) {
-    let rt = Runtime::new(RuntimeConfig::default());
-    let sender = rt.create_sender();
-    (rt, sender)
-}
-
-/// Helper: tick until we receive N messages, returning them.
-fn tick_collect<M: swactor::actor::Message>(
-    rt: &Runtime,
-    inbox: &Inbox<M>,
-    n: usize,
-    max_ticks: usize,
-) -> Vec<M> {
-    let mut msgs = Vec::new();
-    for _ in 0..max_ticks {
-        rt.tick();
-        while let Some(m) = inbox.try_recv() {
-            msgs.push(m);
-            if msgs.len() >= n {
-                return msgs;
-            }
-        }
-    }
-    msgs
-}
-
-use swactor::runtime::ExternalSender;
-
-// ── Spawner actor ───────────────────────────────────────────────────────────
-// We can't call ctx.spawn from outside a handle(), so we use a small "spawner"
-// actor that spawns the process actor and reports its address.
-
-#[derive(Clone)]
-struct SpawnRequest {
-    spec: ProcessSpec,
-    harness: TestHarness,
-    reply_to: ActorAddress,
-    sender: ExternalSender,
-}
-
-#[derive(Clone, Debug)]
-struct SpawnedAddr(ActorAddress);
-
-struct SpawnerActor;
-
-impl ActorInterface for SpawnerActor {
-    type Incoming = SpawnRequest;
-    type Response = SpawnedAddr;
-
-    fn handle(&mut self, ctx: &Ctx, msg: SpawnRequest) {
-        let waker_slot = Arc::new(OnceLock::new());
-        let driver = TestDriver::from_harness(&msg.harness);
-        let addr = spawn_process(ctx, &msg.sender, msg.spec, driver, waker_slot)
-            .expect("spawn_process failed");
-        let _ = ctx.send(msg.reply_to, SpawnedAddr(addr));
-    }
-}
-
-// ── Tests ───────────────────────────────────────────────────────────────────
-
-#[test]
-fn happy_path_spawn_output_exit_notifies_subscriber() {
-    let (rt, sender) = setup();
-    let harness = TestHarness::new();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    // Spawn the spawner actor
-    let spawner_addr = rt.spawn(SpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<SpawnedAddr>().unwrap();
-    rt.tick();
-
-    // Ask spawner to create a process actor
-    rt.send_to(
-        spawner_addr,
-        SpawnRequest {
-            spec: automated_spec(),
-            harness: harness.clone(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-
-    // Tick to process spawn request
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    let spawned = reply_inbox.try_recv().expect("should get spawned addr");
-    let proc_addr = spawned.0;
-
-    // Verify SpawnProcess action was sent to driver
-    let actions = harness.take_actions();
-    assert!(
-        actions
-            .iter()
-            .any(|a| matches!(a, ProcessAction::SpawnProcess { .. })),
-        "driver should receive SpawnProcess, got: {:?}",
-        actions
-    );
-
-    // Subscribe to notifications
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Subscribe {
-            address: *notif_inbox.addr(),
-        },
-    )
-    .unwrap();
-    rt.tick();
-
-    // Inject Started event from "driver"
-    harness.inject(ProcessEvent::Started);
-    // Send PollTick to trigger drain
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    for _ in 0..3 {
-        rt.tick();
-    }
-
-    let msgs = tick_collect(&rt, &notif_inbox, 1, 10);
-    assert!(
-        msgs.iter()
-            .any(|m| matches!(m, ProcessNotification::Started { .. })),
-        "subscriber should get Started notification, got: {:?}",
-        msgs
-    );
-
-    // Inject output
-    harness.inject(ProcessEvent::OutputReceived {
-        data: b"hello\n".to_vec(),
-        is_stderr: false,
-    });
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    let msgs = tick_collect(&rt, &notif_inbox, 1, 10);
-    assert!(
-        msgs.iter()
-            .any(|m| matches!(m, ProcessNotification::Output { .. })),
-        "subscriber should get Output notification"
-    );
-
-    // Inject exit
-    harness.inject(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    let msgs = tick_collect(&rt, &notif_inbox, 1, 10);
-    assert!(
-        msgs.iter().any(|m| matches!(
-            m,
-            ProcessNotification::Exited {
-                status: ExitStatus::Code(0),
-                ..
-            }
-        )),
-        "subscriber should get Exited(0) notification"
-    );
-}
-
-#[test]
-fn polltick_drains_queued_events() {
-    let (rt, sender) = setup();
-    let harness = TestHarness::new();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    let spawner_addr = rt.spawn(SpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<SpawnedAddr>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        SpawnRequest {
-            spec: automated_spec(),
-            harness: harness.clone(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    let proc_addr = reply_inbox.try_recv().unwrap().0;
-
-    // Subscribe
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Subscribe {
-            address: *notif_inbox.addr(),
-        },
-    )
-    .unwrap();
-    rt.tick();
-
-    // Queue multiple events before sending PollTick
-    harness.inject(ProcessEvent::Started);
-    harness.inject(ProcessEvent::OutputReceived {
-        data: b"line1\n".to_vec(),
-        is_stderr: false,
-    });
-    harness.inject(ProcessEvent::OutputReceived {
-        data: b"line2\n".to_vec(),
-        is_stderr: false,
-    });
-
-    // Single PollTick should drain all
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    let msgs = tick_collect(&rt, &notif_inbox, 3, 20);
-
-    assert_eq!(
-        msgs.len(),
-        3,
-        "all three events should produce notifications"
-    );
-    assert!(matches!(msgs[0], ProcessNotification::Started { .. }));
-    assert!(matches!(msgs[1], ProcessNotification::Output { .. }));
-    assert!(matches!(msgs[2], ProcessNotification::Output { .. }));
-}
-
-#[test]
-fn close_command_triggers_graceful_shutdown() {
-    let (rt, sender) = setup();
-    let harness = TestHarness::new();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    let spawner_addr = rt.spawn(SpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<SpawnedAddr>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        SpawnRequest {
-            spec: automated_spec(),
-            harness: harness.clone(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-    let proc_addr = reply_inbox.try_recv().unwrap().0;
-
-    // Subscribe and get to Running state
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Subscribe {
-            address: *notif_inbox.addr(),
-        },
-    )
-    .unwrap();
-    rt.tick();
-    harness.inject(ProcessEvent::Started);
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    let _ = tick_collect::<ProcessNotification>(&rt, &notif_inbox, 1, 10);
-
-    // Send Close
-    harness.take_actions(); // clear previous actions
-    rt.send_to(proc_addr, ProcessCommand::Close).unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    let actions = harness.take_actions();
-    assert!(
-        actions.iter().any(|a| matches!(
-            a,
-            ProcessAction::SendSignal {
-                signal: Signal::Terminate
-            }
-        )),
-        "Close should trigger SIGTERM, got: {:?}",
-        actions
-    );
-}
-
-#[test]
-fn write_stdin_and_signal_forwarded_to_driver() {
-    let (rt, sender) = setup();
-    let harness = TestHarness::new();
-
-    let spawner_addr = rt.spawn(SpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<SpawnedAddr>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        SpawnRequest {
-            spec: automated_spec(),
-            harness: harness.clone(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-    let proc_addr = reply_inbox.try_recv().unwrap().0;
-
-    // Get to Running
-    harness.inject(ProcessEvent::Started);
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    harness.take_actions(); // clear SpawnProcess action
-
-    // Write stdin
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::WriteStdin {
-            data: b"input\n".to_vec(),
-        },
-    )
-    .unwrap();
-    for _ in 0..3 {
-        rt.tick();
-    }
-
-    let actions = harness.take_actions();
-    assert!(
-        actions
-            .iter()
-            .any(|a| matches!(a, ProcessAction::WriteStdin { .. })),
-        "WriteStdin should be forwarded to driver, got: {:?}",
-        actions
-    );
-
-    // Send signal
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::SendSignal {
-            signal: Signal::Interrupt,
-        },
-    )
-    .unwrap();
-    for _ in 0..3 {
-        rt.tick();
-    }
-
-    let actions = harness.take_actions();
-    assert!(
-        actions.iter().any(|a| matches!(
-            a,
-            ProcessAction::SendSignal {
-                signal: Signal::Interrupt
-            }
-        )),
-        "SendSignal should be forwarded to driver, got: {:?}",
-        actions
-    );
-}
-
-#[test]
-fn spawn_failure_notifies_error_and_stops_actor() {
-    let (rt, sender) = setup();
-    let harness = TestHarness::new();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    let spawner_addr = rt.spawn(SpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<SpawnedAddr>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        SpawnRequest {
-            spec: automated_spec(),
-            harness: harness.clone(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-    let proc_addr = reply_inbox.try_recv().unwrap().0;
-
-    // Subscribe
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Subscribe {
-            address: *notif_inbox.addr(),
-        },
-    )
-    .unwrap();
-    rt.tick();
-
-    // Inject spawn failure
-    harness.inject(ProcessEvent::SpawnFailed {
-        reason: "command not found".into(),
-    });
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-
-    let msgs = tick_collect(&rt, &notif_inbox, 1, 20);
-    assert!(
-        msgs.iter()
-            .any(|m| matches!(m, ProcessNotification::Error { .. })),
-        "subscriber should get Error notification on spawn failure"
-    );
-
-    // Actor should have stopped — sending further messages should fail or be ignored
-    // (the address may still be in the map briefly, but the actor won't process)
-    for _ in 0..10 {
-        rt.tick();
-    }
-}
-
-#[test]
-fn subscribe_and_unsubscribe_routing() {
-    let (rt, sender) = setup();
-    let harness = TestHarness::new();
-    let inbox_a = rt.new_inbox::<ProcessNotification>().unwrap();
-    let inbox_b = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    let spawner_addr = rt.spawn(SpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<SpawnedAddr>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        SpawnRequest {
-            spec: automated_spec(),
-            harness: harness.clone(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-    let proc_addr = reply_inbox.try_recv().unwrap().0;
-
-    // Subscribe both
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Subscribe {
-            address: *inbox_a.addr(),
-        },
-    )
-    .unwrap();
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Subscribe {
-            address: *inbox_b.addr(),
-        },
-    )
-    .unwrap();
-    rt.tick();
-
-    // Get to Running
-    harness.inject(ProcessEvent::Started);
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    // Both should have received Started
-    assert!(inbox_a.try_recv().is_some(), "inbox_a should get Started");
-    assert!(inbox_b.try_recv().is_some(), "inbox_b should get Started");
-
-    // Unsubscribe inbox_b
-    rt.send_to(
-        proc_addr,
-        ProcessCommand::Unsubscribe {
-            address: *inbox_b.addr(),
-        },
-    )
-    .unwrap();
-    rt.tick();
-
-    // Inject output — only inbox_a should receive it
-    harness.inject(ProcessEvent::OutputReceived {
-        data: b"data".to_vec(),
-        is_stderr: false,
-    });
-    rt.send_to(proc_addr, ProcessCommand::PollTick).unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    assert!(inbox_a.try_recv().is_some(), "inbox_a should get Output");
-    assert!(
-        inbox_b.try_recv().is_none(),
-        "inbox_b should NOT get Output after unsubscribe"
-    );
-}
diff --git a/crates/process/tests/e2e_process.rs b/crates/process/tests/e2e_process.rs
deleted file mode 100644
index 1878492..0000000
--- a/crates/process/tests/e2e_process.rs
+++ /dev/null
@@ -1,269 +0,0 @@
-//! End-to-end tests: full Runtime + ExternalSender + ProcessActor<LocalDriver>.
-//!
-//! Spawns real OS processes through the actor system and verifies the
-//! complete notification flow.
-
-use std::collections::HashMap;
-
-use swactor::actor::{ActorAddress, ActorInterface, Ctx};
-use swactor::runtime::{ExternalSender, Inbox, Runtime, RuntimeConfig};
-
-use swactor_process::*;
-
-fn automated_spec(cmd: &str, args: &[&str]) -> ProcessSpec {
-    ProcessSpec {
-        command: cmd.into(),
-        args: args.iter().map(|s| s.to_string()).collect(),
-        env: HashMap::new(),
-        working_dir: None,
-        mode: ProcessMode::Automated,
-        initial_pty_size: None,
-        kill_timeout: None,
-        stdin_buffer_limit: None,
-    }
-}
-
-/// Tick and collect up to `n` notifications, with a max tick budget.
-fn tick_collect(
-    rt: &Runtime,
-    inbox: &Inbox<ProcessNotification>,
-    n: usize,
-    max_ticks: usize,
-) -> Vec<ProcessNotification> {
-    let mut msgs = Vec::new();
-    for _ in 0..max_ticks {
-        rt.tick();
-        // Small sleep to let I/O threads produce events
-        std::thread::sleep(std::time::Duration::from_millis(5));
-        while let Some(m) = inbox.try_recv() {
-            msgs.push(m);
-            if msgs.len() >= n {
-                return msgs;
-            }
-        }
-    }
-    msgs
-}
-
-// ── Spawner actor (needed because spawn_local_process requires &Ctx) ────────
-
-#[derive(Clone)]
-struct E2eSpawnRequest {
-    spec: ProcessSpec,
-    subscriber: ActorAddress,
-    reply_to: ActorAddress,
-    sender: ExternalSender,
-}
-
-#[derive(Clone, Debug)]
-struct E2eSpawned(ActorAddress);
-
-struct E2eSpawnerActor;
-
-impl ActorInterface for E2eSpawnerActor {
-    type Incoming = E2eSpawnRequest;
-    type Response = E2eSpawned;
-
-    fn handle(&mut self, ctx: &Ctx, msg: E2eSpawnRequest) {
-        let addr =
-            spawn_local_process(ctx, &msg.sender, msg.spec).expect("spawn_local_process failed");
-        // Subscribe the notification inbox
-        let _ = ctx.send(
-            addr,
-            ProcessCommand::Subscribe {
-                address: msg.subscriber,
-            },
-        );
-        let _ = ctx.send(msg.reply_to, E2eSpawned(addr));
-    }
-}
-
-// ── Tests ───────────────────────────────────────────────────────────────────
-
-#[test]
-fn echo_hello_full_lifecycle() {
-    let rt = Runtime::new(RuntimeConfig::default());
-    let sender = rt.create_sender();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    let spawner_addr = rt.spawn(E2eSpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<E2eSpawned>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        E2eSpawnRequest {
-            spec: automated_spec("echo", &["hello"]),
-            subscriber: *notif_inbox.addr(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-
-    // Tick enough for the spawner to process + the process actor to start
-    for _ in 0..10 {
-        rt.tick();
-        std::thread::sleep(std::time::Duration::from_millis(5));
-    }
-
-    let spawned = reply_inbox.try_recv().expect("should get spawned address");
-    let _proc_addr = spawned.0;
-
-    // Collect notifications: Started, Output("hello\n"), Exited(0)
-    let msgs = tick_collect(&rt, &notif_inbox, 3, 200);
-
-    let has_started = msgs
-        .iter()
-        .any(|m| matches!(m, ProcessNotification::Started { .. }));
-    let has_output = msgs.iter().any(|m| {
-        if let ProcessNotification::Output { data, .. } = m {
-            String::from_utf8_lossy(data).contains("hello")
-        } else {
-            false
-        }
-    });
-    let has_exited = msgs.iter().any(|m| {
-        matches!(
-            m,
-            ProcessNotification::Exited {
-                status: ExitStatus::Code(0),
-                ..
-            }
-        )
-    });
-
-    assert!(
-        has_started,
-        "should receive Started notification, got: {:?}",
-        msgs
-    );
-    assert!(
-        has_output,
-        "should receive Output with 'hello', got: {:?}",
-        msgs
-    );
-    assert!(
-        has_exited,
-        "should receive Exited(0) notification, got: {:?}",
-        msgs
-    );
-
-    // Verify ordering: Started before Output before Exited
-    let started_idx = msgs
-        .iter()
-        .position(|m| matches!(m, ProcessNotification::Started { .. }))
-        .unwrap();
-    let output_idx = msgs
-        .iter()
-        .position(|m| matches!(m, ProcessNotification::Output { .. }))
-        .unwrap();
-    let exited_idx = msgs
-        .iter()
-        .position(|m| matches!(m, ProcessNotification::Exited { .. }))
-        .unwrap();
-
-    assert!(
-        started_idx < output_idx,
-        "Started should come before Output"
-    );
-    assert!(output_idx < exited_idx, "Output should come before Exited");
-}
-
-/// The per-node process-output observer is the mechanism a telemetry node uses
-/// to tap *every* managed process with no per-spawn wiring: it installs one
-/// observer on its runtime, and any process spawned through the facility hands
-/// its output there, labeled by command basename. This is the contract a node's
-/// `proc.<label>.*` capture relies on, so it must hold for a real spawn driven
-/// only through the public Runtime + `spawn_local_process` API.
-#[test]
-fn runtime_observer_taps_managed_process_output_by_basename() {
-    use std::sync::{Arc, Mutex};
-    use swactor::process_observer::ProcessOutputObserver;
-
-    #[derive(Default)]
-    struct Recorder {
-        // (label, is_stderr, text) for each chunk observed.
-        seen: Mutex<Vec<(String, bool, String)>>,
-    }
-    impl ProcessOutputObserver for Recorder {
-        fn on_output(&self, label: &str, is_stderr: bool, data: &[u8]) {
-            self.seen.lock().unwrap().push((
-                label.to_string(),
-                is_stderr,
-                String::from_utf8_lossy(data).into_owned(),
-            ));
-        }
-    }
-
-    let rt = Runtime::new(RuntimeConfig::default());
-    let recorder = Arc::new(Recorder::default());
-    // Install the observer before the first managed process is spawned.
-    rt.set_process_output_observer(recorder.clone());
-
-    let sender = rt.create_sender();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-    let spawner_addr = rt.spawn(E2eSpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<E2eSpawned>().unwrap();
-    rt.tick();
-
-    // A path command so the basename (`echo`) is what labels the output, not the
-    // full path — the node keys `proc.<label>.*` on the basename.
-    rt.send_to(
-        spawner_addr,
-        E2eSpawnRequest {
-            spec: automated_spec("/bin/echo", &["telemetry-line"]),
-            subscriber: *notif_inbox.addr(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-
-    // Drive until the process has produced output (also drains the inbox).
-    let _ = tick_collect(&rt, &notif_inbox, 3, 200);
-
-    let seen = recorder.seen.lock().unwrap().clone();
-    let captured = seen.iter().any(|(label, is_stderr, text)| {
-        label == "echo" && !*is_stderr && text.contains("telemetry-line")
-    });
-    assert!(
-        captured,
-        "observer should capture stdout of the managed process under its command basename, got: {seen:?}"
-    );
-}
-
-#[test]
-fn bad_command_reports_error_e2e() {
-    let rt = Runtime::new(RuntimeConfig::default());
-    let sender = rt.create_sender();
-    let notif_inbox = rt.new_inbox::<ProcessNotification>().unwrap();
-
-    let spawner_addr = rt.spawn(E2eSpawnerActor).unwrap();
-    let reply_inbox = rt.new_inbox::<E2eSpawned>().unwrap();
-    rt.tick();
-
-    rt.send_to(
-        spawner_addr,
-        E2eSpawnRequest {
-            spec: automated_spec("/nonexistent/binary/xyz", &[]),
-            subscriber: *notif_inbox.addr(),
-            reply_to: *reply_inbox.addr(),
-            sender: sender.clone(),
-        },
-    )
-    .unwrap();
-
-    for _ in 0..10 {
-        rt.tick();
-        std::thread::sleep(std::time::Duration::from_millis(5));
-    }
-
-    let msgs = tick_collect(&rt, &notif_inbox, 1, 200);
-    assert!(
-        msgs.iter()
-            .any(|m| matches!(m, ProcessNotification::Error { .. })),
-        "should receive Error notification for bad command, got: {:?}",
-        msgs
-    );
-}
diff --git a/crates/process/tests/local_driver.rs b/crates/process/tests/local_driver.rs
deleted file mode 100644
index cc4afb0..0000000
--- a/crates/process/tests/local_driver.rs
+++ /dev/null
@@ -1,342 +0,0 @@
-//! Layer 4 — LocalDriver integration tests.
-//!
-//! Real OS processes, no actor layer. Tests LocalDriver in isolation.
-
-use std::collections::HashMap;
-use std::sync::{Arc, OnceLock};
-use std::thread;
-use std::time::Duration;
-
-use swactor_process::*;
-
-fn automated_spec(cmd: &str, args: &[&str]) -> ProcessSpec {
-    ProcessSpec {
-        command: cmd.into(),
-        args: args.iter().map(|s| s.to_string()).collect(),
-        env: HashMap::new(),
-        working_dir: None,
-        mode: ProcessMode::Automated,
-        initial_pty_size: None,
-        kill_timeout: None,
-        stdin_buffer_limit: None,
-    }
-}
-
-/// Poll the driver until `pred` matches at least one collected event, or timeout.
-fn poll_until_match(
-    driver: &mut LocalDriver,
-    timeout: Duration,
-    pred: impl Fn(&ProcessEvent) -> bool,
-) -> Vec<ProcessEvent> {
-    let start = std::time::Instant::now();
-    let mut all_events = Vec::new();
-    loop {
-        let events = driver.poll();
-        if events.is_empty() {
-            if start.elapsed() >= timeout {
-                break;
-            }
-            thread::sleep(Duration::from_millis(10));
-        }
-        all_events.extend(events);
-        if all_events.iter().any(&pred) {
-            break;
-        }
-    }
-    all_events
-}
-
-fn has_event(events: &[ProcessEvent], pred: impl Fn(&ProcessEvent) -> bool) -> bool {
-    events.iter().any(pred)
-}
-
-#[test]
-fn echo_produces_started_output_and_exit_zero() {
-    let queue = EventQueue::new();
-    let waker_slot = Arc::new(OnceLock::new());
-    let mut driver = LocalDriver::new(queue, waker_slot);
-
-    let spec = automated_spec("echo", &["hello"]);
-    driver.execute(ProcessAction::SpawnProcess { spec });
-
-    // Wait for Exited (which means Started + output + exit are all in)
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Exited { .. })
-    });
-
-    assert!(
-        has_event(&events, |e| matches!(e, ProcessEvent::Started)),
-        "should have Started event, got: {:?}",
-        events
-    );
-    assert!(
-        has_event(&events, |e| matches!(
-            e,
-            ProcessEvent::OutputReceived {
-                is_stderr: false,
-                ..
-            }
-        )),
-        "should have stdout OutputReceived"
-    );
-
-    // Check the output contains "hello"
-    let output: Vec<u8> = events
-        .iter()
-        .filter_map(|e| match e {
-            ProcessEvent::OutputReceived {
-                data,
-                is_stderr: false,
-            } => Some(data.clone()),
-            _ => None,
-        })
-        .flatten()
-        .collect();
-    let output_str = String::from_utf8_lossy(&output);
-    assert!(
-        output_str.contains("hello"),
-        "output should contain 'hello', got: {:?}",
-        output_str
-    );
-
-    assert!(
-        has_event(&events, |e| matches!(
-            e,
-            ProcessEvent::Exited {
-                status: ExitStatus::Code(0)
-            }
-        )),
-        "should have Exited(0)"
-    );
-}
-
-#[test]
-fn cat_stdin_echo_and_close() {
-    let queue = EventQueue::new();
-    let waker_slot = Arc::new(OnceLock::new());
-    let mut driver = LocalDriver::new(queue, waker_slot);
-
-    let spec = automated_spec("cat", &[]);
-    driver.execute(ProcessAction::SpawnProcess { spec });
-
-    // Wait for Started
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Started)
-    });
-    assert!(has_event(&events, |e| matches!(e, ProcessEvent::Started)));
-
-    // Write to stdin
-    driver.execute(ProcessAction::WriteStdin {
-        data: b"ping\n".to_vec(),
-    });
-
-    // Wait until we see actual output (not just the StdinWritten ack)
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::OutputReceived { .. })
-    });
-    let output: Vec<u8> = events
-        .iter()
-        .filter_map(|e| match e {
-            ProcessEvent::OutputReceived { data, .. } => Some(data.clone()),
-            _ => None,
-        })
-        .flatten()
-        .collect();
-    let output_str = String::from_utf8_lossy(&output);
-    assert!(
-        output_str.contains("ping"),
-        "cat should echo back 'ping', got: {:?}",
-        output_str
-    );
-
-    // Close stdin — cat should exit
-    driver.execute(ProcessAction::CloseStdin);
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Exited { .. })
-    });
-    assert!(
-        has_event(&events, |e| matches!(
-            e,
-            ProcessEvent::Exited {
-                status: ExitStatus::Code(0)
-            }
-        )),
-        "cat should exit cleanly after stdin close, got: {:?}",
-        events
-    );
-}
-
-#[test]
-fn signal_terminates_long_running_process() {
-    let queue = EventQueue::new();
-    let waker_slot = Arc::new(OnceLock::new());
-    let mut driver = LocalDriver::new(queue, waker_slot);
-
-    let spec = automated_spec("sleep", &["60"]);
-    driver.execute(ProcessAction::SpawnProcess { spec });
-
-    // Wait for Started
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Started)
-    });
-    assert!(has_event(&events, |e| matches!(e, ProcessEvent::Started)));
-
-    // Send SIGTERM
-    driver.execute(ProcessAction::SendSignal {
-        signal: Signal::Terminate,
-    });
-
-    // Wait for Exited (may also see SignalSent ack first)
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Exited { .. })
-    });
-    assert!(
-        has_event(&events, |e| matches!(
-            e,
-            ProcessEvent::Exited {
-                status: ExitStatus::Signal(_)
-            }
-        )),
-        "sleep should exit with signal status after SIGTERM, got: {:?}",
-        events
-    );
-}
-
-#[test]
-fn bad_command_produces_spawn_failed() {
-    let queue = EventQueue::new();
-    let waker_slot = Arc::new(OnceLock::new());
-    let mut driver = LocalDriver::new(queue, waker_slot);
-
-    let spec = automated_spec("/nonexistent/binary/that/does/not/exist", &[]);
-    driver.execute(ProcessAction::SpawnProcess { spec });
-
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::SpawnFailed { .. })
-    });
-    assert!(
-        has_event(&events, |e| matches!(e, ProcessEvent::SpawnFailed { .. })),
-        "nonexistent binary should produce SpawnFailed, got: {:?}",
-        events
-    );
-}
-
-#[test]
-fn large_output_no_data_loss() {
-    let queue = EventQueue::new();
-    let waker_slot = Arc::new(OnceLock::new());
-    let mut driver = LocalDriver::new(queue, waker_slot);
-
-    // Generate a large amount of output: seq 1 10000
-    let spec = automated_spec("seq", &["1", "10000"]);
-    driver.execute(ProcessAction::SpawnProcess { spec });
-
-    // Collect all events until exit
-    let events = poll_until_match(&mut driver, Duration::from_secs(10), |e| {
-        matches!(e, ProcessEvent::Exited { .. })
-    });
-
-    // Gather all output
-    let output: Vec<u8> = events
-        .iter()
-        .filter_map(|e| match e {
-            ProcessEvent::OutputReceived { data, .. } => Some(data.clone()),
-            _ => None,
-        })
-        .flatten()
-        .collect();
-
-    let output_str = String::from_utf8_lossy(&output);
-    // seq 1 10000 should end with "10000\n"
-    assert!(
-        output_str.contains("10000"),
-        "large output should contain '10000'"
-    );
-    // Check that it starts with "1\n"
-    assert!(
-        output_str.starts_with("1\n"),
-        "large output should start with '1\\n'"
-    );
-
-    assert!(
-        has_event(&events, |e| matches!(
-            e,
-            ProcessEvent::Exited {
-                status: ExitStatus::Code(0)
-            }
-        )),
-        "seq should exit cleanly"
-    );
-}
-
-#[test]
-fn kill_timeout_escalates_to_sigkill() {
-    let queue = EventQueue::new();
-    let waker_slot = Arc::new(OnceLock::new());
-    let mut driver = LocalDriver::new(queue, waker_slot);
-
-    // Spawn a process that traps SIGTERM. Use exec to replace the shell so
-    // SIGTERM goes directly to the perl process (avoids shell vs child races).
-    let spec = automated_spec("perl", &["-e", "$SIG{TERM} = 'IGNORE'; sleep 300"]);
-    driver.execute(ProcessAction::SpawnProcess { spec });
-
-    // Wait for Started
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Started)
-    });
-    assert!(has_event(&events, |e| matches!(e, ProcessEvent::Started)));
-
-    // Give the process a moment to set up the trap
-    thread::sleep(Duration::from_millis(100));
-
-    // Send SIGTERM (the process ignores it)
-    driver.execute(ProcessAction::SendSignal {
-        signal: Signal::Terminate,
-    });
-    poll_until_match(&mut driver, Duration::from_secs(1), |e| {
-        matches!(e, ProcessEvent::SignalSent)
-    });
-
-    // Verify the process is still alive after a short wait (SIGTERM was ignored)
-    thread::sleep(Duration::from_millis(200));
-    let events = driver.poll();
-    assert!(
-        !has_event(&events, |e| matches!(e, ProcessEvent::Exited { .. })),
-        "process should still be alive after SIGTERM (trap should ignore it)"
-    );
-
-    // Schedule a short kill timeout
-    driver.execute(ProcessAction::ScheduleKillTimeout {
-        duration: Duration::from_millis(200),
-    });
-
-    // Wait for KillTimeout event
-    let events = poll_until_match(&mut driver, Duration::from_secs(3), |e| {
-        matches!(e, ProcessEvent::KillTimeout)
-    });
-    assert!(
-        has_event(&events, |e| matches!(e, ProcessEvent::KillTimeout)),
-        "should receive KillTimeout, got: {:?}",
-        events
-    );
-
-    // Now send SIGKILL
-    driver.execute(ProcessAction::SendSignal {
-        signal: Signal::Kill,
-    });
-
-    // Wait for exit
-    let events = poll_until_match(&mut driver, Duration::from_secs(5), |e| {
-        matches!(e, ProcessEvent::Exited { .. })
-    });
-    assert!(
-        has_event(&events, |e| matches!(
-            e,
-            ProcessEvent::Exited {
-                status: ExitStatus::Signal(_)
-            }
-        )),
-        "process should exit with signal after SIGKILL, got: {:?}",
-        events
-    );
-}
diff --git a/crates/process/tests/proptest_session.rs b/crates/process/tests/proptest_session.rs
deleted file mode 100644
index 203de97..0000000
--- a/crates/process/tests/proptest_session.rs
+++ /dev/null
@@ -1,203 +0,0 @@
-use std::collections::HashMap;
-
-use proptest::prelude::*;
-use swactor::actor::ActorAddress;
-use swactor_process::*;
-
-fn automated_spec() -> ProcessSpec {
-    ProcessSpec {
-        command: "test".into(),
-        args: vec![],
-        env: HashMap::new(),
-        working_dir: None,
-        mode: ProcessMode::Automated,
-        initial_pty_size: None,
-        kill_timeout: None,
-        stdin_buffer_limit: None,
-    }
-}
-
-fn addr(n: u8) -> ActorAddress {
-    let mut bytes = [0u8; 32];
-    bytes[0] = n;
-    ActorAddress(bytes)
-}
-
-fn arb_signal() -> impl Strategy<Value = Signal> {
-    prop_oneof![
-        Just(Signal::Terminate),
-        Just(Signal::Kill),
-        Just(Signal::Hangup),
-        Just(Signal::Interrupt),
-        (0..32i32).prop_map(Signal::Other),
-    ]
-}
-
-fn arb_event() -> impl Strategy<Value = ProcessEvent> {
-    prop_oneof![
-        Just(ProcessEvent::Started),
-        Just(ProcessEvent::KillTimeout),
-        ".*".prop_map(|reason| ProcessEvent::SpawnFailed { reason }),
-        proptest::collection::vec(any::<u8>(), 0..64).prop_map(|data| {
-            ProcessEvent::OutputReceived {
-                data,
-                is_stderr: false,
-            }
-        }),
-        proptest::collection::vec(any::<u8>(), 0..64).prop_map(|data| {
-            ProcessEvent::OutputReceived {
-                data,
-                is_stderr: true,
-            }
-        }),
-        prop_oneof![
-            any::<i32>().prop_map(ExitStatus::Code),
-            any::<i32>().prop_map(ExitStatus::Signal),
-            Just(ExitStatus::Unknown),
-        ]
-        .prop_map(|status| ProcessEvent::Exited { status }),
-        ".*".prop_map(|reason| ProcessEvent::ConnectionLost { reason }),
-        (0..5usize).prop_map(|n| ProcessEvent::StdinWritten { byte_count: n * 10 }),
-        Just(ProcessEvent::SignalSent),
-        Just(ProcessEvent::PtyResized),
-        proptest::collection::vec(any::<u8>(), 0..64)
-            .prop_map(|data| ProcessEvent::WriteStdin { data }),
-        arb_signal().prop_map(|signal| ProcessEvent::SendSignal { signal }),
-        Just(ProcessEvent::ResizePty {
-            size: PtySize { cols: 80, rows: 24 },
-        }),
-        Just(ProcessEvent::CloseStdin),
-        Just(ProcessEvent::CloseRequested),
-        (0..4u8).prop_map(|n| ProcessEvent::Subscribe { address: addr(n) }),
-        (0..4u8).prop_map(|n| ProcessEvent::Unsubscribe { address: addr(n) }),
-    ]
-}
-
-// ──────────────────────────────────────────────
-// 1. No panics for arbitrary event sequences
-// ──────────────────────────────────────────────
-
-proptest! {
-    #[test]
-    fn no_panics_on_arbitrary_events(events in proptest::collection::vec(arb_event(), 0..50)) {
-        let (mut session, _) = ProcessSession::new(automated_spec());
-        for event in events {
-            let _ = session.apply(event);
-        }
-    }
-}
-
-// ──────────────────────────────────────────────
-// 2. Exited is terminal
-// ──────────────────────────────────────────────
-
-proptest! {
-    #[test]
-    fn exited_is_terminal(events in proptest::collection::vec(arb_event(), 0..50)) {
-        let (mut session, _) = ProcessSession::new(automated_spec());
-        let mut reached_exited = false;
-
-        for event in events {
-            let _ = session.apply(event);
-            if session.state() == ProcessState::Exited {
-                reached_exited = true;
-            }
-            if reached_exited {
-                prop_assert_eq!(session.state(), ProcessState::Exited);
-            }
-        }
-    }
-}
-
-// ──────────────────────────────────────────────
-// 3. SelfTerminate always last action when entering Exited
-// ──────────────────────────────────────────────
-
-proptest! {
-    #[test]
-    fn self_terminate_is_last_when_entering_exited(events in proptest::collection::vec(arb_event(), 0..50)) {
-        let (mut session, _) = ProcessSession::new(automated_spec());
-        let mut was_exited = false;
-
-        for event in events {
-            let prev_state = session.state();
-            let actions = session.apply(event);
-
-            // If we just transitioned into Exited
-            if session.state() == ProcessState::Exited && !was_exited && prev_state != ProcessState::Exited {
-                prop_assert!(
-                    matches!(actions.last(), Some(ProcessAction::SelfTerminate)),
-                    "SelfTerminate must be last action when entering Exited, got: {:?}", actions
-                );
-            }
-
-            if session.state() == ProcessState::Exited {
-                was_exited = true;
-            }
-        }
-    }
-}
-
-// ──────────────────────────────────────────────
-// 4. Subscriber count matches add/remove operations
-// ──────────────────────────────────────────────
-
-proptest! {
-    #[test]
-    fn subscriber_count_is_consistent(
-        ops in proptest::collection::vec(
-            prop_oneof![
-                (0..8u8).prop_map(|n| (true, n)),
-                (0..8u8).prop_map(|n| (false, n)),
-            ],
-            0..30
-        )
-    ) {
-        let (mut session, _) = ProcessSession::new(automated_spec());
-        let mut expected: Vec<u8> = Vec::new();
-
-        for (is_add, n) in ops {
-            if is_add {
-                session.apply(ProcessEvent::Subscribe { address: addr(n) });
-                if !expected.contains(&n) {
-                    expected.push(n);
-                }
-            } else {
-                session.apply(ProcessEvent::Unsubscribe { address: addr(n) });
-                expected.retain(|&x| x != n);
-            }
-            prop_assert_eq!(session.subscriber_count(), expected.len());
-        }
-    }
-}
-
-// ──────────────────────────────────────────────
-// 5. State monotonicity (never goes backward)
-// ──────────────────────────────────────────────
-
-fn state_ordinal(s: ProcessState) -> u8 {
-    match s {
-        ProcessState::Starting => 0,
-        ProcessState::Running => 1,
-        ProcessState::Stopping => 2,
-        ProcessState::Exited => 3,
-    }
-}
-
-proptest! {
-    #[test]
-    fn state_never_goes_backward(events in proptest::collection::vec(arb_event(), 0..50)) {
-        let (mut session, _) = ProcessSession::new(automated_spec());
-        let mut max_ordinal = state_ordinal(session.state());
-
-        for event in events {
-            let _ = session.apply(event);
-            let current = state_ordinal(session.state());
-            prop_assert!(
-                current >= max_ordinal,
-                "State went backward: ordinal {} -> {}", max_ordinal, current
-            );
-            max_ordinal = current;
-        }
-    }
-}
diff --git a/crates/process/tests/public_api_stage1.rs b/crates/process/tests/public_api_stage1.rs
new file mode 100644
index 0000000..338d443
--- /dev/null
+++ b/crates/process/tests/public_api_stage1.rs
@@ -0,0 +1,54 @@
+use std::collections::HashMap;
+use std::time::Duration;
+
+use swactor_process::{
+    ExitStatus, ProcessCommand, ProcessOutput, ProcessSpec, send_process_command,
+};
+
+#[test]
+fn stage1_public_api_exposes_only_target_process_shapes() {
+    let spec = ProcessSpec {
+        command: "echo".to_string(),
+        args: vec!["ok".to_string()],
+        env: HashMap::new(),
+        working_dir: None,
+        label: Some("echo_ok".to_string()),
+    };
+    assert_eq!(spec.label.as_deref(), Some("echo_ok"));
+
+    let stop = ProcessCommand::Stop {
+        kill_after: Some(Duration::from_millis(10)),
+    };
+    assert!(matches!(
+        stop,
+        ProcessCommand::Stop {
+            kill_after: Some(_)
+        }
+    ));
+
+    let outputs = [
+        ProcessOutput::Started { pid: 1 },
+        ProcessOutput::SpawnFailed {
+            error: "spawn failed".to_string(),
+        },
+        ProcessOutput::Exited {
+            status: ExitStatus::Code(0),
+        },
+        ProcessOutput::Error {
+            error: "supervisor failed".to_string(),
+        },
+    ];
+    assert!(matches!(outputs[0], ProcessOutput::Started { pid: 1 }));
+    assert!(matches!(
+        outputs[2],
+        ProcessOutput::Exited {
+            status: ExitStatus::Code(0)
+        }
+    ));
+
+    let _send: fn(
+        &swactor::runtime::ExternalSender,
+        swactor::actor::ActorAddress,
+        ProcessCommand,
+    ) -> Result<(), swactor::Error> = send_process_command;
+}
diff --git a/crates/process/tests/public_api_stage2.rs b/crates/process/tests/public_api_stage2.rs
new file mode 100644
index 0000000..f02351f
--- /dev/null
+++ b/crates/process/tests/public_api_stage2.rs
@@ -0,0 +1,974 @@
+use std::collections::HashMap;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::time::{Duration, Instant};
+
+use datastream::{DatastreamEndpoint, DatastreamEvent, Lifetime, NodeId, StreamId};
+use serde_json::{Value, json};
+use swactor::actor::{ActorAddress, ActorInterface, Ctx};
+use swactor::runtime::{ExternalSender, Inbox, Runtime, RuntimeConfig};
+use swactor_process::{
+    ExitStatus, ProcessCommand, ProcessOutput, ProcessOutputConfig, ProcessSpec,
+    send_process_command, spawn_local_process,
+};
+
+#[derive(Clone)]
+struct SpawnRequest {
+    spec: ProcessSpec,
+    output: ProcessOutputConfig,
+    sender: ExternalSender,
+    reply_to: ActorAddress,
+}
+
+#[derive(Clone, Debug)]
+enum SpawnReply {
+    Spawned(ActorAddress),
+    Failed(String),
+}
+
+struct SpawnerActor;
+
+impl ActorInterface for SpawnerActor {
+    type Incoming = SpawnRequest;
+    type Response = ();
+
+    fn handle(&mut self, ctx: &Ctx, msg: SpawnRequest) {
+        let reply = match spawn_local_process(ctx, &msg.sender, msg.spec, msg.output) {
+            Ok(addr) => SpawnReply::Spawned(addr),
+            Err(err) => SpawnReply::Failed(err.to_string()),
+        };
+        let _ = ctx.send(msg.reply_to, reply);
+    }
+}
+
+static NEXT_STREAM: AtomicU64 = AtomicU64::new(1);
+
+fn stage2_stream() -> StreamId {
+    let id = NEXT_STREAM.fetch_add(1, Ordering::Relaxed);
+    StreamId::new(NodeId::new(format!("process-stage2-{id}")), Lifetime(2))
+}
+
+fn shell_spec(command: &str, args: Vec<&str>, label: Option<&str>) -> ProcessSpec {
+    ProcessSpec {
+        command: command.to_owned(),
+        args: args.into_iter().map(str::to_owned).collect(),
+        env: HashMap::new(),
+        working_dir: None,
+        label: label.map(str::to_owned),
+    }
+}
+
+fn drain_outputs(inbox: &Inbox<ProcessOutput>, outputs: &mut Vec<ProcessOutput>) {
+    while let Some(output) = inbox.try_recv() {
+        outputs.push(output);
+    }
+}
+
+fn drive_once(
+    rt: &Runtime,
+    endpoint: Option<&DatastreamEndpoint>,
+    upstream: &Inbox<ProcessOutput>,
+    outputs: &mut Vec<ProcessOutput>,
+) {
+    rt.tick();
+    std::thread::sleep(Duration::from_millis(5));
+    if let Some(endpoint) = endpoint {
+        endpoint.tick();
+    }
+    drain_outputs(upstream, outputs);
+}
+
+fn send_spawn(
+    rt: &Runtime,
+    spawner: ActorAddress,
+    sender: &ExternalSender,
+    spec: ProcessSpec,
+    output: ProcessOutputConfig,
+    reply: &Inbox<SpawnReply>,
+) {
+    rt.send_to(
+        spawner,
+        SpawnRequest {
+            spec,
+            output,
+            sender: sender.clone(),
+            reply_to: *reply.addr(),
+        },
+    )
+    .unwrap();
+}
+
+fn drive_until_spawn_reply(
+    rt: &Runtime,
+    endpoint: Option<&DatastreamEndpoint>,
+    upstream: &Inbox<ProcessOutput>,
+    outputs: &mut Vec<ProcessOutput>,
+    reply: &Inbox<SpawnReply>,
+) -> SpawnReply {
+    for _ in 0..400 {
+        drive_once(rt, endpoint, upstream, outputs);
+        if let Some(reply) = reply.try_recv() {
+            return reply;
+        }
+    }
+    panic!("spawner did not reply; outputs={outputs:?}");
+}
+
+fn drive_until(
+    rt: &Runtime,
+    endpoint: Option<&DatastreamEndpoint>,
+    upstream: &Inbox<ProcessOutput>,
+    outputs: &mut Vec<ProcessOutput>,
+    mut done: impl FnMut(&[ProcessOutput]) -> bool,
+) {
+    for _ in 0..800 {
+        drive_once(rt, endpoint, upstream, outputs);
+        if done(outputs) {
+            return;
+        }
+    }
+    panic!("runtime condition was not reached; outputs={outputs:?}");
+}
+
+fn expect_spawned(reply: SpawnReply) -> ActorAddress {
+    match reply {
+        SpawnReply::Spawned(addr) => {
+            assert_ne!(addr, ActorAddress::default());
+            addr
+        }
+        SpawnReply::Failed(error) => panic!("spawn helper failed: {error}"),
+    }
+}
+
+fn expect_failed(reply: SpawnReply) -> String {
+    match reply {
+        SpawnReply::Spawned(addr) => panic!("spawn helper unexpectedly spawned {addr:?}"),
+        SpawnReply::Failed(error) => error,
+    }
+}
+
+fn is_terminal(output: &ProcessOutput) -> bool {
+    matches!(
+        output,
+        ProcessOutput::SpawnFailed { .. }
+            | ProcessOutput::Exited { .. }
+            | ProcessOutput::Error { .. }
+    )
+}
+
+fn terminal_count(outputs: &[ProcessOutput]) -> usize {
+    outputs.iter().filter(|output| is_terminal(output)).count()
+}
+
+fn has_started(outputs: &[ProcessOutput]) -> bool {
+    outputs
+        .iter()
+        .any(|output| matches!(output, ProcessOutput::Started { pid } if *pid > 0))
+}
+
+fn has_exited(outputs: &[ProcessOutput], status: ExitStatus) -> bool {
+    outputs.iter().any(|output| {
+        matches!(
+            output,
+            ProcessOutput::Exited { status: observed } if *observed == status
+        )
+    })
+}
+
+fn has_spawn_failed(outputs: &[ProcessOutput]) -> bool {
+    outputs
+        .iter()
+        .any(|output| matches!(output, ProcessOutput::SpawnFailed { .. }))
+}
+
+fn assert_no_errors(outputs: &[ProcessOutput]) {
+    assert!(
+        !outputs
+            .iter()
+            .any(|output| matches!(output, ProcessOutput::Error { .. })),
+        "unexpected process error output: {outputs:?}"
+    );
+}
+
+fn assert_no_spawn_failed(outputs: &[ProcessOutput]) {
+    assert!(
+        !has_spawn_failed(outputs),
+        "unexpected spawn failure output: {outputs:?}"
+    );
+}
+
+fn started_index(outputs: &[ProcessOutput]) -> usize {
+    outputs
+        .iter()
+        .position(|output| matches!(output, ProcessOutput::Started { pid } if *pid > 0))
+        .unwrap_or_else(|| panic!("missing Started output: {outputs:?}"))
+}
+
+fn exited_index(outputs: &[ProcessOutput]) -> usize {
+    outputs
+        .iter()
+        .position(|output| matches!(output, ProcessOutput::Exited { .. }))
+        .unwrap_or_else(|| panic!("missing Exited output: {outputs:?}"))
+}
+
+fn channel_names(endpoint: &DatastreamEndpoint) -> Vec<String> {
+    endpoint
+        .catalog_snapshot()
+        .channels
+        .values()
+        .map(|descriptor| descriptor.name.clone())
+        .collect()
+}
+
+#[test]
+fn lifecycle_outputs_are_sent_upstream_and_mirrored_to_datastream() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+    let endpoint = DatastreamEndpoint::new(stage2_stream());
+    let subscription = endpoint.subscribe_all("process-stage2-lifecycle");
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "sh",
+            vec!["-c", "echo stdout; echo stderr >&2; exit 0"],
+            Some("trainer.0/foo"),
+        ),
+        ProcessOutputConfig::datastream_mirror(*upstream.addr(), endpoint.producer()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        Some(&endpoint),
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    assert_ne!(process_addr, ActorAddress::default());
+
+    let mut datastream_events = subscription.drain_available();
+    drive_until(&rt, Some(&endpoint), &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+    for _ in 0..5 {
+        drive_once(&rt, Some(&endpoint), &upstream, &mut outputs);
+        datastream_events.extend(subscription.drain_available());
+    }
+
+    let started = started_index(&outputs);
+    let exited = exited_index(&outputs);
+    assert!(
+        started < exited,
+        "Started should be delivered before Exited: {outputs:?}"
+    );
+    assert_no_spawn_failed(&outputs);
+    assert_no_errors(&outputs);
+
+    let names = channel_names(&endpoint);
+    assert!(
+        names
+            .iter()
+            .any(|name| name == "proc.trainer_0_foo.lifecycle"),
+        "catalog should contain lifecycle channel, got {names:?}"
+    );
+    assert!(
+        names
+            .iter()
+            .all(|name| !name.contains("stdout") && !name.contains("stderr")),
+        "process core should not register stdout/stderr channels: {names:?}"
+    );
+
+    let payloads: Vec<Value> = datastream_events
+        .iter()
+        .filter_map(|event| match event {
+            DatastreamEvent::Frame(delivery) => serde_json::from_slice(&delivery.payload).ok(),
+            _ => None,
+        })
+        .collect();
+    assert!(
+        payloads.iter().any(|payload| {
+            payload.get("event") == Some(&Value::String("started".to_owned()))
+                && payload
+                    .get("pid")
+                    .and_then(Value::as_u64)
+                    .is_some_and(|pid| pid > 0)
+        }),
+        "lifecycle mirror should include started JSON, got {payloads:?}"
+    );
+    assert!(
+        payloads.iter().any(|payload| {
+            payload.get("event") == Some(&Value::String("exited".to_owned()))
+                && payload.get("status") == Some(&json!({"kind": "code", "value": 0}))
+        }),
+        "lifecycle mirror should include exited JSON, got {payloads:?}"
+    );
+    assert!(
+        payloads.iter().all(|payload| {
+            payload.get("event") != Some(&Value::String("stdout".to_owned()))
+                && payload.get("event") != Some(&Value::String("stderr".to_owned()))
+        }),
+        "lifecycle mirror should not include child output events: {payloads:?}"
+    );
+}
+
+#[test]
+fn spawn_failure_maps_to_public_spawn_failed_output() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "/definitely/not/a/real/binary",
+            Vec::new(),
+            Some("missing-binary"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let _process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, has_spawn_failed);
+
+    let spawn_failures: Vec<&String> = outputs
+        .iter()
+        .filter_map(|output| match output {
+            ProcessOutput::SpawnFailed { error } => Some(error),
+            _ => None,
+        })
+        .collect();
+    assert_eq!(
+        spawn_failures.len(),
+        1,
+        "expected exactly one spawn failure output, got {outputs:?}"
+    );
+    assert!(
+        !spawn_failures[0].is_empty(),
+        "spawn failure error should not be empty"
+    );
+    assert!(
+        !outputs
+            .iter()
+            .any(|output| matches!(output, ProcessOutput::Started { .. })),
+        "spawn failure should not emit Started: {outputs:?}"
+    );
+    assert!(
+        !outputs
+            .iter()
+            .any(|output| matches!(output, ProcessOutput::Exited { .. })),
+        "spawn failure should not emit Exited: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn command_basename_is_default_lifecycle_label_source() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+    let endpoint = DatastreamEndpoint::new(stage2_stream());
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec("/bin/sh", vec!["-c", "exit 0"], None),
+        ProcessOutputConfig::datastream_mirror(*upstream.addr(), endpoint.producer()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let _process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        Some(&endpoint),
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, Some(&endpoint), &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+
+    let names = channel_names(&endpoint);
+    assert!(
+        names.iter().any(|name| name == "proc.sh.lifecycle"),
+        "catalog should contain basename lifecycle channel, got {names:?}"
+    );
+    assert!(started_index(&outputs) < exited_index(&outputs));
+    assert_no_spawn_failed(&outputs);
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn explicit_label_overrides_basename_and_duplicate_labels_are_rejected() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+    let endpoint = DatastreamEndpoint::new(stage2_stream());
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec("/bin/sh", vec!["-c", "sleep 2"], Some("trainer.0/foo")),
+        ProcessOutputConfig::datastream_mirror(*upstream.addr(), endpoint.producer()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let first_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        Some(&endpoint),
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec("/bin/echo", vec!["unused"], Some("trainer.0/foo")),
+        ProcessOutputConfig::datastream_mirror(*upstream.addr(), endpoint.producer()),
+        &reply,
+    );
+    let error = expect_failed(drive_until_spawn_reply(
+        &rt,
+        Some(&endpoint),
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    assert!(
+        error.contains(
+            "duplicate process lifecycle datastream channel: proc.trainer_0_foo.lifecycle"
+        ),
+        "duplicate label error should name lifecycle channel, got {error}"
+    );
+
+    send_process_command(
+        &sender,
+        first_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_millis(20)),
+        },
+    )
+    .unwrap();
+    drive_until(&rt, Some(&endpoint), &upstream, &mut outputs, |outputs| {
+        outputs
+            .iter()
+            .any(|output| matches!(output, ProcessOutput::Exited { .. }))
+    });
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn stop_before_spawn_success_reports_started_then_exited() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec("sh", vec!["-c", "sleep 60"], Some("stop-before-start")),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_millis(20)),
+        },
+    )
+    .unwrap();
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        outputs
+            .iter()
+            .any(|output| matches!(output, ProcessOutput::Exited { .. }))
+    });
+
+    assert!(started_index(&outputs) < exited_index(&outputs));
+    assert_eq!(
+        outputs
+            .iter()
+            .filter(|output| matches!(output, ProcessOutput::Exited { .. }))
+            .count(),
+        1,
+        "expected exactly one Exited output, got {outputs:?}"
+    );
+    assert_eq!(
+        terminal_count(&outputs),
+        1,
+        "unexpected terminal outputs: {outputs:?}"
+    );
+    assert_no_spawn_failed(&outputs);
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn stop_before_spawn_failure_reports_only_spawn_failed() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "/definitely/not/a/real/binary",
+            Vec::new(),
+            Some("stop-before-spawn-failure"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_millis(20)),
+        },
+    )
+    .unwrap();
+    drive_until(&rt, None, &upstream, &mut outputs, has_spawn_failed);
+
+    assert_eq!(
+        terminal_count(&outputs),
+        1,
+        "unexpected terminal outputs: {outputs:?}"
+    );
+    assert!(
+        !has_started(&outputs),
+        "spawn failure should not emit Started: {outputs:?}"
+    );
+    assert!(
+        !outputs
+            .iter()
+            .any(|output| matches!(output, ProcessOutput::Exited { .. })),
+        "spawn failure should not emit Exited: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn stop_running_with_kill_after_escalates_to_kill() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "sh",
+            vec!["-c", "trap '' TERM; while true; do sleep 1; done"],
+            Some("kill-escalates"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, has_started);
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_millis(20)),
+        },
+    )
+    .unwrap();
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Signal(9))
+    });
+
+    assert!(
+        has_exited(&outputs, ExitStatus::Signal(9)),
+        "expected SIGKILL exit: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn stop_running_without_kill_after_terminates_without_kill_escalation() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "sh",
+            vec!["-c", "trap 'exit 0' TERM; while true; do sleep 1; done"],
+            Some("terminate-without-kill"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, has_started);
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop { kill_after: None },
+    )
+    .unwrap();
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+
+    assert!(
+        has_exited(&outputs, ExitStatus::Code(0)),
+        "expected graceful exit: {outputs:?}"
+    );
+    assert!(
+        !has_exited(&outputs, ExitStatus::Signal(9)),
+        "stop without deadline should not escalate to SIGKILL: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn child_exit_before_kill_deadline_suppresses_kill_escalation() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "sh",
+            vec!["-c", "trap 'exit 0' TERM; while true; do sleep 1; done"],
+            Some("deadline-suppresses-kill"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, has_started);
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_secs(1)),
+        },
+    )
+    .unwrap();
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+    for _ in 0..5 {
+        drive_once(&rt, None, &upstream, &mut outputs);
+    }
+
+    assert!(
+        has_exited(&outputs, ExitStatus::Code(0)),
+        "expected graceful exit: {outputs:?}"
+    );
+    assert!(
+        !has_exited(&outputs, ExitStatus::Signal(9)),
+        "child exit before deadline should suppress SIGKILL: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn duplicate_stop_while_stopping_is_noop_and_keeps_original_deadline() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "sh",
+            vec!["-c", "trap '' TERM; while true; do sleep 1; done"],
+            Some("duplicate-stop"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, has_started);
+
+    let first_stop = Instant::now();
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_millis(250)),
+        },
+    )
+    .unwrap();
+    send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_secs(5)),
+        },
+    )
+    .unwrap();
+
+    while first_stop.elapsed() < Duration::from_secs(2) {
+        drive_once(&rt, None, &upstream, &mut outputs);
+        if has_exited(&outputs, ExitStatus::Signal(9)) {
+            break;
+        }
+    }
+
+    assert!(
+        has_exited(&outputs, ExitStatus::Signal(9)),
+        "duplicate stop should keep the original kill deadline: {outputs:?}"
+    );
+    assert!(
+        first_stop.elapsed() < Duration::from_secs(2),
+        "SIGKILL arrived too late after duplicate stop: {:?}",
+        first_stop.elapsed()
+    );
+    assert_eq!(
+        terminal_count(&outputs),
+        1,
+        "unexpected terminal outputs: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn stop_after_terminal_output_emits_no_additional_output() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec("sh", vec!["-c", "exit 0"], Some("post-terminal-stop")),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+    let output_len = outputs.len();
+
+    let _ = send_process_command(
+        &sender,
+        process_addr,
+        ProcessCommand::Stop {
+            kill_after: Some(Duration::from_millis(10)),
+        },
+    );
+    for _ in 0..10 {
+        drive_once(&rt, None, &upstream, &mut outputs);
+    }
+
+    assert_eq!(
+        outputs.len(),
+        output_len,
+        "post-terminal stop should not emit more output: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+}
+
+#[test]
+fn lifecycle_mirror_submit_failure_does_not_suppress_upstream_or_emit_error() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+    let endpoint = DatastreamEndpoint::with_capacity(stage2_stream(), 1, 16);
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec("sh", vec!["-c", "exit 0"], Some("mirror-drop")),
+        ProcessOutputConfig::datastream_mirror(*upstream.addr(), endpoint.producer()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let _process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+    let dropped = endpoint.mux().dropped();
+    endpoint.tick();
+
+    assert!(
+        has_started(&outputs),
+        "upstream should receive Started: {outputs:?}"
+    );
+    assert!(
+        has_exited(&outputs, ExitStatus::Code(0)),
+        "upstream should receive Exited: {outputs:?}"
+    );
+    assert_no_errors(&outputs);
+    assert!(
+        dropped > 0,
+        "full lifecycle mirror mux should drop at least one frame"
+    );
+}
+
+#[test]
+fn stdout_and_stderr_writes_do_not_affect_lifecycle() {
+    let rt = Runtime::new(RuntimeConfig::default());
+    let sender = rt.create_sender();
+    let upstream = rt.new_inbox::<ProcessOutput>().unwrap();
+    let reply = rt.new_inbox::<SpawnReply>().unwrap();
+    let spawner = rt.spawn(SpawnerActor).unwrap();
+
+    send_spawn(
+        &rt,
+        spawner,
+        &sender,
+        shell_spec(
+            "sh",
+            vec![
+                "-c",
+                "for i in $(seq 1 1000); do echo out; echo err >&2; done; exit 0",
+            ],
+            Some("child-output-is-null"),
+        ),
+        ProcessOutputConfig::disabled(*upstream.addr()),
+        &reply,
+    );
+
+    let mut outputs = Vec::new();
+    let _process_addr = expect_spawned(drive_until_spawn_reply(
+        &rt,
+        None,
+        &upstream,
+        &mut outputs,
+        &reply,
+    ));
+    drive_until(&rt, None, &upstream, &mut outputs, |outputs| {
+        has_exited(outputs, ExitStatus::Code(0))
+    });
+
+    assert_eq!(
+        outputs.len(),
+        2,
+        "process core should emit only lifecycle outputs: {outputs:?}"
+    );
+    assert!(started_index(&outputs) < exited_index(&outputs));
+    assert!(
+        has_exited(&outputs, ExitStatus::Code(0)),
+        "expected clean exit: {outputs:?}"
+    );
+    assert_no_spawn_failed(&outputs);
+    assert_no_errors(&outputs);
+}
diff --git a/crates/process/tests/session_scenarios.rs b/crates/process/tests/session_scenarios.rs
deleted file mode 100644
index e6b3ce4..0000000
--- a/crates/process/tests/session_scenarios.rs
+++ /dev/null
@@ -1,787 +0,0 @@
-use std::collections::HashMap;
-use std::time::Duration;
-
-use swactor::actor::ActorAddress;
-use swactor_process::*;
-
-fn automated_spec() -> ProcessSpec {
-    ProcessSpec {
-        command: "echo".into(),
-        args: vec!["hello".into()],
-        env: HashMap::new(),
-        working_dir: None,
-        mode: ProcessMode::Automated,
-        initial_pty_size: None,
-        kill_timeout: None,
-        stdin_buffer_limit: None,
-    }
-}
-
-fn spec_with_kill_timeout(timeout: Duration) -> ProcessSpec {
-    ProcessSpec {
-        kill_timeout: Some(timeout),
-        ..automated_spec()
-    }
-}
-
-fn spec_with_stdin_limit(limit: usize) -> ProcessSpec {
-    ProcessSpec {
-        stdin_buffer_limit: Some(limit),
-        ..automated_spec()
-    }
-}
-
-fn interactive_spec() -> ProcessSpec {
-    ProcessSpec {
-        command: "/bin/bash".into(),
-        args: vec![],
-        env: HashMap::new(),
-        working_dir: None,
-        mode: ProcessMode::Interactive,
-        initial_pty_size: Some(PtySize { cols: 80, rows: 24 }),
-        kill_timeout: None,
-        stdin_buffer_limit: None,
-    }
-}
-
-fn addr(n: u8) -> ActorAddress {
-    let mut bytes = [0u8; 32];
-    bytes[0] = n;
-    ActorAddress(bytes)
-}
-
-/// Verify that a SelfTerminate is present and is the last action.
-fn assert_self_terminate_is_last(actions: &[ProcessAction]) {
-    assert!(
-        matches!(actions.last(), Some(ProcessAction::SelfTerminate)),
-        "SelfTerminate must be the last action, got: {actions:?}"
-    );
-}
-
-// ──────────────────────────────────────────────
-// 1. Happy path — automated process
-// ──────────────────────────────────────────────
-
-#[test]
-fn automated_process_runs_produces_output_and_exits_cleanly() {
-    let (mut session, init) = ProcessSession::new(automated_spec());
-    assert_eq!(session.state(), ProcessState::Starting);
-    assert!(matches!(&init[0], ProcessAction::SpawnProcess { .. }));
-
-    // Process starts
-    let actions = session.apply(ProcessEvent::Started);
-    assert_eq!(session.state(), ProcessState::Running);
-    assert!(matches!(&actions[0], ProcessAction::NotifyStarted { .. }));
-
-    // Some output arrives
-    let actions = session.apply(ProcessEvent::OutputReceived {
-        data: b"hello\n".to_vec(),
-        is_stderr: false,
-    });
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyOutput {
-            stream: OutputStream::Stdout,
-            ..
-        }
-    ));
-
-    // More output on stderr
-    let actions = session.apply(ProcessEvent::OutputReceived {
-        data: b"warn\n".to_vec(),
-        is_stderr: true,
-    });
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyOutput {
-            stream: OutputStream::Stderr,
-            ..
-        }
-    ));
-
-    // Process exits
-    let actions = session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-    assert_eq!(session.exit_status(), Some(ExitStatus::Code(0)));
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// 2. Interactive process with subscriber lifecycle
-// ──────────────────────────────────────────────
-
-#[test]
-fn interactive_session_manages_subscribers_correctly() {
-    let (mut session, _) = ProcessSession::new(interactive_spec());
-
-    // Add two subscribers before start
-    session.apply(ProcessEvent::Subscribe { address: addr(1) });
-    session.apply(ProcessEvent::Subscribe { address: addr(2) });
-    assert_eq!(session.subscriber_count(), 2);
-
-    // Duplicate add is a no-op
-    session.apply(ProcessEvent::Subscribe { address: addr(1) });
-    assert_eq!(session.subscriber_count(), 2);
-
-    // Start — both subscribers notified
-    let actions = session.apply(ProcessEvent::Started);
-    match &actions[0] {
-        ProcessAction::NotifyStarted { subscribers } => {
-            assert_eq!(subscribers.len(), 2);
-        }
-        other => panic!("expected NotifyStarted, got {other:?}"),
-    }
-
-    // Remove one subscriber
-    session.apply(ProcessEvent::Unsubscribe { address: addr(1) });
-    assert_eq!(session.subscriber_count(), 1);
-
-    // Output only goes to remaining subscriber
-    let actions = session.apply(ProcessEvent::OutputReceived {
-        data: b"data".to_vec(),
-        is_stderr: false,
-    });
-    match &actions[0] {
-        ProcessAction::NotifyOutput { subscribers, .. } => {
-            assert_eq!(subscribers, &vec![addr(2)]);
-        }
-        other => panic!("expected NotifyOutput, got {other:?}"),
-    }
-
-    // Exit
-    let actions = session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-    match &actions[0] {
-        ProcessAction::NotifyExited { subscribers, .. } => {
-            assert_eq!(subscribers, &vec![addr(2)]);
-        }
-        other => panic!("expected NotifyExited, got {other:?}"),
-    }
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// 3. Spawn failure
-// ──────────────────────────────────────────────
-
-#[test]
-fn spawn_failure_notifies_and_self_terminates() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Subscribe { address: addr(1) });
-
-    let actions = session.apply(ProcessEvent::SpawnFailed {
-        reason: "command not found".into(),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyError {
-            error: ProcessError::SpawnFailed { .. },
-            ..
-        }
-    ));
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// 4. Connection loss mid-run
-// ──────────────────────────────────────────────
-
-#[test]
-fn connection_loss_during_running_transitions_to_exited() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-
-    let actions = session.apply(ProcessEvent::ConnectionLost {
-        reason: "pipe broken".into(),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-    assert_eq!(session.exit_status(), Some(ExitStatus::Unknown));
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyError {
-            error: ProcessError::ConnectionLost { .. },
-            ..
-        }
-    ));
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// 5. Close requested before start
-// ──────────────────────────────────────────────
-
-#[test]
-fn close_before_start_sends_signal_on_belated_start() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-
-    // Close requested while still Starting
-    let actions = session.apply(ProcessEvent::CloseRequested);
-    assert!(actions.is_empty());
-    assert_eq!(session.state(), ProcessState::Starting);
-
-    // Process starts belatedly — should immediately get SIGTERM
-    let actions = session.apply(ProcessEvent::Started);
-    assert_eq!(session.state(), ProcessState::Stopping);
-    assert!(matches!(&actions[0], ProcessAction::NotifyStarted { .. }));
-    assert!(matches!(
-        &actions[1],
-        ProcessAction::SendSignal {
-            signal: Signal::Terminate
-        }
-    ));
-}
-
-// ──────────────────────────────────────────────
-// 6. Invalid operations produce errors, not panics
-// ──────────────────────────────────────────────
-
-#[test]
-fn invalid_event_in_starting_produces_error() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-
-    let actions = session.apply(ProcessEvent::WriteStdin {
-        data: b"hi".to_vec(),
-    });
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyError {
-            error: ProcessError::InvalidState {
-                attempted: "WriteStdin",
-                current_state: "Starting"
-            },
-            ..
-        }
-    ));
-    // State unchanged
-    assert_eq!(session.state(), ProcessState::Starting);
-}
-
-#[test]
-fn invalid_event_in_exited_produces_error() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::SpawnFailed {
-        reason: "no".into(),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-
-    let actions = session.apply(ProcessEvent::WriteStdin {
-        data: b"hi".to_vec(),
-    });
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyError {
-            error: ProcessError::InvalidState {
-                attempted: "WriteStdin",
-                current_state: "Exited"
-            },
-            ..
-        }
-    ));
-}
-
-// ──────────────────────────────────────────────
-// 7. Stdin closed then write → error
-// ──────────────────────────────────────────────
-
-#[test]
-fn write_after_stdin_closed_produces_error() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-
-    let actions = session.apply(ProcessEvent::CloseStdin);
-    assert!(matches!(&actions[0], ProcessAction::CloseStdin));
-    assert!(session.stdin_closed());
-
-    // Duplicate close is a no-op
-    let actions = session.apply(ProcessEvent::CloseStdin);
-    assert!(actions.is_empty());
-
-    // Write after close → error
-    let actions = session.apply(ProcessEvent::WriteStdin {
-        data: b"too late".to_vec(),
-    });
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::NotifyError {
-            error: ProcessError::InvalidState { .. },
-            ..
-        }
-    ));
-}
-
-// ──────────────────────────────────────────────
-// 8. MockDriver round-trip (driver + session tick loop)
-// ──────────────────────────────────────────────
-
-#[test]
-fn mock_driver_round_trip() {
-    let (mut session, init_actions) = ProcessSession::new(automated_spec());
-    let mut driver = MockDriver::new();
-
-    // Execute initial actions (SpawnProcess)
-    for action in init_actions {
-        driver.execute(action);
-    }
-    assert!(matches!(
-        &driver.executed_actions()[0],
-        ProcessAction::SpawnProcess { .. }
-    ));
-
-    // Simulate: driver produces Started
-    driver.inject(ProcessEvent::Started);
-
-    // Tick loop: poll → apply → execute
-    let events = driver.poll();
-    for event in events {
-        let actions = session.apply(event);
-        for action in actions {
-            driver.execute(action);
-        }
-    }
-    assert_eq!(session.state(), ProcessState::Running);
-
-    // Simulate output and exit
-    driver.inject(ProcessEvent::OutputReceived {
-        data: b"done".to_vec(),
-        is_stderr: false,
-    });
-    driver.inject(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-
-    let events = driver.poll();
-    for event in events {
-        let actions = session.apply(event);
-        for action in actions {
-            driver.execute(action);
-        }
-    }
-
-    assert_eq!(session.state(), ProcessState::Exited);
-
-    // Verify the driver saw the expected sequence
-    let all_actions = driver.take_executed_actions();
-    assert!(matches!(
-        &all_actions[0],
-        ProcessAction::SpawnProcess { .. }
-    ));
-    assert!(matches!(
-        &all_actions[1],
-        ProcessAction::NotifyStarted { .. }
-    ));
-    assert!(matches!(
-        &all_actions[2],
-        ProcessAction::NotifyOutput { .. }
-    ));
-    assert!(matches!(
-        &all_actions[3],
-        ProcessAction::NotifyExited { .. }
-    ));
-    assert!(matches!(&all_actions[4], ProcessAction::SelfTerminate));
-}
-
-// ──────────────────────────────────────────────
-// 9. Signal escalation in Stopping
-// ──────────────────────────────────────────────
-
-#[test]
-fn signal_escalation_allowed_in_stopping() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-    session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-
-    // Escalate to Kill
-    let actions = session.apply(ProcessEvent::SendSignal {
-        signal: Signal::Kill,
-    });
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::SendSignal {
-            signal: Signal::Kill
-        }
-    ));
-
-    // Can still receive output while stopping
-    let actions = session.apply(ProcessEvent::OutputReceived {
-        data: b"final".to_vec(),
-        is_stderr: false,
-    });
-    assert!(matches!(&actions[0], ProcessAction::NotifyOutput { .. }));
-
-    // Finally exits
-    let actions = session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Signal(9),
-    });
-    assert_eq!(session.exit_status(), Some(ExitStatus::Signal(9)));
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// 10. Late acks in Exited silently consumed
-// ──────────────────────────────────────────────
-
-#[test]
-fn late_acks_in_exited_are_silently_consumed() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-    session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-
-    // Acks should produce no actions, no errors
-    assert!(
-        session
-            .apply(ProcessEvent::StdinWritten { byte_count: 10 })
-            .is_empty()
-    );
-    assert!(session.apply(ProcessEvent::SignalSent).is_empty());
-    assert!(session.apply(ProcessEvent::PtyResized).is_empty());
-
-    // Subscribe/Unsubscribe also still works in Exited
-    assert!(
-        session
-            .apply(ProcessEvent::Subscribe { address: addr(1) })
-            .is_empty()
-    );
-    assert_eq!(session.subscriber_count(), 1);
-    assert!(
-        session
-            .apply(ProcessEvent::Unsubscribe { address: addr(1) })
-            .is_empty()
-    );
-    assert_eq!(session.subscriber_count(), 0);
-}
-
-// ──────────────────────────────────────────────
-// Flow control tracking
-// ──────────────────────────────────────────────
-
-#[test]
-fn flow_control_tracks_pending_stdin_bytes() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![0u8; 100],
-    });
-    assert_eq!(session.flow_control().pending_stdin_bytes, 100);
-
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![0u8; 50],
-    });
-    assert_eq!(session.flow_control().pending_stdin_bytes, 150);
-
-    session.apply(ProcessEvent::StdinWritten { byte_count: 80 });
-    assert_eq!(session.flow_control().pending_stdin_bytes, 70);
-
-    // Ack more than pending → saturates at 0
-    session.apply(ProcessEvent::StdinWritten { byte_count: 200 });
-    assert_eq!(session.flow_control().pending_stdin_bytes, 0);
-}
-
-// ──────────────────────────────────────────────
-// CloseStdin in Stopping
-// ──────────────────────────────────────────────
-
-#[test]
-fn close_stdin_allowed_in_stopping() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-    session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-
-    let actions = session.apply(ProcessEvent::CloseStdin);
-    assert!(matches!(&actions[0], ProcessAction::CloseStdin));
-    assert!(session.stdin_closed());
-}
-
-// ──────────────────────────────────────────────
-// Connection loss in Stopping
-// ──────────────────────────────────────────────
-
-#[test]
-fn connection_loss_in_stopping_transitions_to_exited() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-    session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-
-    let actions = session.apply(ProcessEvent::ConnectionLost {
-        reason: "gone".into(),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// Redundant CloseRequested in Stopping is no-op
-// ──────────────────────────────────────────────
-
-#[test]
-fn duplicate_close_requested_in_stopping_is_noop() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-    session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-
-    let actions = session.apply(ProcessEvent::CloseRequested);
-    assert!(actions.is_empty());
-    assert_eq!(session.state(), ProcessState::Stopping);
-}
-
-// ──────────────────────────────────────────────
-// Kill timeout — A1–A6
-// ──────────────────────────────────────────────
-
-#[test]
-fn close_requested_with_kill_timeout_schedules_timer() {
-    let (mut session, _) = ProcessSession::new(spec_with_kill_timeout(Duration::from_secs(5)));
-    session.apply(ProcessEvent::Started);
-
-    let actions = session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::SendSignal {
-            signal: Signal::Terminate
-        }
-    ));
-    assert!(matches!(
-        &actions[1],
-        ProcessAction::ScheduleKillTimeout { duration } if *duration == Duration::from_secs(5)
-    ));
-}
-
-#[test]
-fn close_before_start_with_kill_timeout_schedules_timer_on_belated_start() {
-    let (mut session, _) = ProcessSession::new(spec_with_kill_timeout(Duration::from_secs(3)));
-    session.apply(ProcessEvent::CloseRequested);
-
-    let actions = session.apply(ProcessEvent::Started);
-    assert_eq!(session.state(), ProcessState::Stopping);
-    assert!(matches!(&actions[0], ProcessAction::NotifyStarted { .. }));
-    assert!(matches!(
-        &actions[1],
-        ProcessAction::SendSignal {
-            signal: Signal::Terminate
-        }
-    ));
-    assert!(matches!(
-        &actions[2],
-        ProcessAction::ScheduleKillTimeout { duration } if *duration == Duration::from_secs(3)
-    ));
-}
-
-#[test]
-fn kill_timeout_in_stopping_sends_sigkill() {
-    let (mut session, _) = ProcessSession::new(spec_with_kill_timeout(Duration::from_secs(5)));
-    session.apply(ProcessEvent::Started);
-    session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-
-    let actions = session.apply(ProcessEvent::KillTimeout);
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::SendSignal {
-            signal: Signal::Kill
-        }
-    ));
-    assert_eq!(session.state(), ProcessState::Stopping);
-}
-
-#[test]
-fn kill_timeout_silently_consumed_outside_stopping() {
-    // Starting
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    assert!(session.apply(ProcessEvent::KillTimeout).is_empty());
-    assert_eq!(session.state(), ProcessState::Starting);
-
-    // Running
-    session.apply(ProcessEvent::Started);
-    assert!(session.apply(ProcessEvent::KillTimeout).is_empty());
-    assert_eq!(session.state(), ProcessState::Running);
-
-    // Exited
-    session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-    assert!(session.apply(ProcessEvent::KillTimeout).is_empty());
-    assert_eq!(session.state(), ProcessState::Exited);
-}
-
-#[test]
-fn close_requested_without_kill_timeout_no_schedule_action() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-
-    let actions = session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(actions.len(), 1);
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::SendSignal {
-            signal: Signal::Terminate
-        }
-    ));
-}
-
-#[test]
-fn kill_timeout_full_escalation_to_sigkill_then_exit() {
-    let (mut session, _) = ProcessSession::new(spec_with_kill_timeout(Duration::from_secs(1)));
-    session.apply(ProcessEvent::Started);
-
-    // CloseRequested → SIGTERM + schedule
-    let actions = session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.state(), ProcessState::Stopping);
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::SendSignal {
-            signal: Signal::Terminate
-        }
-    ));
-    assert!(matches!(
-        &actions[1],
-        ProcessAction::ScheduleKillTimeout { .. }
-    ));
-
-    // KillTimeout fires → SIGKILL
-    let actions = session.apply(ProcessEvent::KillTimeout);
-    assert!(matches!(
-        &actions[0],
-        ProcessAction::SendSignal {
-            signal: Signal::Kill
-        }
-    ));
-
-    // Process finally exits via signal 9
-    let actions = session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Signal(9),
-    });
-    assert_eq!(session.state(), ProcessState::Exited);
-    assert_eq!(session.exit_status(), Some(ExitStatus::Signal(9)));
-    assert_self_terminate_is_last(&actions);
-}
-
-// ──────────────────────────────────────────────
-// Backpressure — B1–B5
-// ──────────────────────────────────────────────
-
-#[test]
-fn backpressure_buffers_when_over_limit() {
-    let (mut session, _) = ProcessSession::new(spec_with_stdin_limit(100));
-    session.apply(ProcessEvent::Started);
-
-    // First write (50 bytes) — under limit, passes through
-    let actions = session.apply(ProcessEvent::WriteStdin {
-        data: vec![1u8; 50],
-    });
-    assert_eq!(actions.len(), 1);
-    assert!(matches!(&actions[0], ProcessAction::WriteStdin { .. }));
-    assert_eq!(session.flow_control().pending_stdin_bytes, 50);
-
-    // Second write (60 bytes) — still under limit (50 < 100), passes through
-    let actions = session.apply(ProcessEvent::WriteStdin {
-        data: vec![2u8; 60],
-    });
-    assert_eq!(actions.len(), 1);
-    assert_eq!(session.flow_control().pending_stdin_bytes, 110);
-
-    // Third write (30 bytes) — now at 110 >= 100, buffered
-    let actions = session.apply(ProcessEvent::WriteStdin {
-        data: vec![3u8; 30],
-    });
-    assert!(actions.is_empty());
-    assert_eq!(session.stdin_buffer_bytes(), 30);
-    // pending_stdin_bytes unchanged (buffered data not counted as pending)
-    assert_eq!(session.flow_control().pending_stdin_bytes, 110);
-}
-
-#[test]
-fn stdin_written_ack_drains_buffer() {
-    let (mut session, _) = ProcessSession::new(spec_with_stdin_limit(100));
-    session.apply(ProcessEvent::Started);
-
-    // Fill up: 100 bytes pending
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![1u8; 100],
-    });
-    assert_eq!(session.flow_control().pending_stdin_bytes, 100);
-
-    // Buffer two chunks
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![2u8; 40],
-    });
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![3u8; 30],
-    });
-    assert_eq!(session.stdin_buffer_bytes(), 70);
-
-    // Ack 80 bytes → pending drops to 20, buffer should drain in FIFO order
-    let actions = session.apply(ProcessEvent::StdinWritten { byte_count: 80 });
-    // pending was 100, now 20. Drain first chunk (40 bytes) → pending = 60.
-    // 60 < 100, drain second chunk (30 bytes) → pending = 90.
-    // 90 < 100, buffer empty.
-    assert_eq!(actions.len(), 2);
-    assert!(matches!(&actions[0], ProcessAction::WriteStdin { data } if data.len() == 40));
-    assert!(matches!(&actions[1], ProcessAction::WriteStdin { data } if data.len() == 30));
-    assert_eq!(session.flow_control().pending_stdin_bytes, 90);
-    assert_eq!(session.stdin_buffer_bytes(), 0);
-}
-
-#[test]
-fn close_requested_clears_stdin_buffer() {
-    let (mut session, _) = ProcessSession::new(spec_with_stdin_limit(50));
-    session.apply(ProcessEvent::Started);
-
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![1u8; 60],
-    });
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![2u8; 30],
-    });
-    assert_eq!(session.stdin_buffer_bytes(), 30);
-
-    session.apply(ProcessEvent::CloseRequested);
-    assert_eq!(session.stdin_buffer_bytes(), 0);
-}
-
-#[test]
-fn no_backpressure_when_limit_is_none() {
-    let (mut session, _) = ProcessSession::new(automated_spec());
-    session.apply(ProcessEvent::Started);
-
-    // All writes pass through regardless of pending bytes
-    for _ in 0..10 {
-        let actions = session.apply(ProcessEvent::WriteStdin {
-            data: vec![0u8; 1000],
-        });
-        assert_eq!(actions.len(), 1);
-        assert!(matches!(&actions[0], ProcessAction::WriteStdin { .. }));
-    }
-    assert_eq!(session.flow_control().pending_stdin_bytes, 10_000);
-    assert_eq!(session.stdin_buffer_bytes(), 0);
-}
-
-#[test]
-fn exit_clears_stdin_buffer() {
-    let (mut session, _) = ProcessSession::new(spec_with_stdin_limit(50));
-    session.apply(ProcessEvent::Started);
-
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![1u8; 60],
-    });
-    session.apply(ProcessEvent::WriteStdin {
-        data: vec![2u8; 30],
-    });
-    assert_eq!(session.stdin_buffer_bytes(), 30);
-
-    session.apply(ProcessEvent::Exited {
-        status: ExitStatus::Code(0),
-    });
-    assert_eq!(session.stdin_buffer_bytes(), 0);
-}
diff --git a/src/actor.rs b/src/actor.rs
index b1bccc3..1a36824 100644
--- a/src/actor.rs
+++ b/src/actor.rs
@@ -681,14 +681,6 @@ impl<'a> Ctx<'a> {
         self.inner.extension()
     }
 
-    /// Access the per-runtime process-output observer (if installed). The
-    /// process facility reads this when spawning so every managed process's
-    /// output is taped automatically.
-    pub fn process_output_observer(
-        &self,
-    ) -> Option<std::sync::Arc<dyn crate::process_observer::ProcessOutputObserver>> {
-        self.inner.process_output_observer()
-    }
 
     /// Return system-level information (worker count, actor count, uptime).
     pub fn system_info(&self) -> SystemInfo {
diff --git a/src/process_observer.rs b/src/process_observer.rs
index 5065e88..6f69fb9 100644
--- a/src/process_observer.rs
+++ b/src/process_observer.rs
@@ -1,20 +1,16 @@
-//! Per-runtime hook for observing output from processes spawned through the
-//! process facility.
+//! Legacy/custom hook for adapters that choose to observe stdout/stderr bytes.
 //!
-//! This trait lives in swactor rather than `swactor-process` so the runtime can
-//! store an observer without a dependency cycle: `swactor-process` depends on
-//! swactor, and a telemetry emitter (which lives even higher up) implements this
-//! trait. The runtime is merely the carrier — it never interprets the bytes.
+//! Current `swactor-process` managed-process core does not call this hook.
+//! Managed-process lifecycle/control output is delivered as `ProcessOutput` to
+//! the configured upstream owner and may be mirrored to datastream through
+//! `ProcessOutputConfig::datastream_mirror`.
 //!
-//! The observer is per-node (per-runtime), installed via
-//! [`Runtime::set_process_output_observer`](crate::runtime::Runtime::set_process_output_observer).
-//! The process facility hands every managed process's output to it automatically,
-//! labeled by the process's command basename, so a node taps all of its managed
-//! processes with no per-spawn wiring.
+//! The runtime is only the storage location for callers that still wire this
+//! hook themselves; it does not interpret the bytes.
 
-/// Observes every chunk of stdout/stderr from processes the runtime spawns.
+/// Observes chunks supplied by legacy/custom process-output adapters.
 pub trait ProcessOutputObserver: Send + Sync {
-    /// `label` identifies the process (its command basename); `is_stderr`
-    /// selects the stream; `data` is one raw output chunk.
+    /// `label` identifies the adapter-defined source; `is_stderr` selects the
+    /// stream; `data` is one raw output chunk.
     fn on_output(&self, label: &str, is_stderr: bool, data: &[u8]);
 }
diff --git a/src/runtime.rs b/src/runtime.rs
index 79408b1..3218f51 100644
--- a/src/runtime.rs
+++ b/src/runtime.rs
@@ -598,17 +598,6 @@ impl Runtime {
         self.stats_hook = Some(hook);
     }
 
-    /// Install the per-node process-output observer. Every process spawned
-    /// through the process facility on this runtime hands its stdout/stderr to
-    /// `obs`, labeled by command basename. Takes `&self` (the slot is a
-    /// `OnceLock`) so it can be installed on an already-shared `Arc<Runtime>`,
-    /// before the first managed process is spawned. Subsequent calls are no-ops.
-    pub fn set_process_output_observer(
-        &self,
-        obs: Arc<dyn crate::process_observer::ProcessOutputObserver>,
-    ) {
-        let _ = self.process_output_observer.set(obs);
-    }
 
     /// Set the sink for non-local (remote) message delivery.
     ///