chore(runtime): remove Runlet sidechannel progress tracking

docs/user/compose-and-local-tools.md

@@ -32,7 +32,7 @@ Retries repeat the body. Do not retry a write unless repeating it is safe or the
 
 Background calls no longer hold their originating turn open, and interrupting that turn does not stop them. When a call detaches, the model receives its tool-call ID and can stop it with `close({ call_id: "call_..." })`. Cancellation is delivered through the same result lifecycle as completion, as a failed result reporting that tool execution was cancelled.
 
-The TUI keeps every running call visible. A running compose card shows its Runlet source inline, with live call states, binding resolution, and loop or retry counts. Completion replaces the source with the compose output. Unless the user explicitly opened or closed it, the output collapses when a later tool call or model message arrives and remains available from the tool card. Completion or failure is delivered back to the owning session and wakes the session loop directly without inserting synthetic user content. Background work is process- and session-scoped rather than a durable operating-system job, so closing Kit ends its inspectable lifetime.
+The TUI keeps every running call visible. A running compose card groups its canonical ACP child tool calls. Its Runlet source is available as a bounded, neutral view; the display does not infer binding, loop, or retry state. Completion replaces the source with the compose output. Unless the user explicitly opened or closed it, the output collapses when a later tool call or model message arrives and remains available from the tool card. Completion or failure is delivered back to the owning session and wakes the session loop directly without inserting synthetic user content. Background work is process- and session-scoped rather than a durable operating-system job, so closing Kit ends its inspectable lifetime.
 
 ## Ordering, dependencies, and concurrency
 

src/acp_child.rs

@@ -1248,12 +1248,7 @@ struct RunConfig {
 fn harness_diagnostic(label: &str, line: &str) -> Option<String> {
     if matches!(
         crate::events::parse(line),
-        Some(
-            crate::events::RuntimeEvent::ChildStarted { .. }
-                | crate::events::RuntimeEvent::ChildFinished { .. }
-                | crate::events::RuntimeEvent::RunletProgress { .. }
-                | crate::events::RuntimeEvent::RunletTransport { .. }
-        )
+        Some(crate::events::RuntimeEvent::RunletTransport { .. })
     ) {
         return None;
     }
@@ -1361,12 +1356,12 @@ async fn run(
             ancestor_id.as_deref(),
             |output| match output {
                 ForwardedStderr::RuntimeLine(line) => {
-                    if let Some(transport) = crate::runlet_progress::transport::global() {
+                    if let Some(transport) = crate::diagnostic_transport::global() {
                         transport.publish_runtime_line(&line);
                     }
                 }
                 ForwardedStderr::Diagnostic(line) => {
-                    if let Some(transport) = crate::runlet_progress::transport::global() {
+                    if let Some(transport) = crate::diagnostic_transport::global() {
                         transport.publish_line(&line);
                     }
                 }
@@ -2003,9 +1998,8 @@ async fn forward_stderr(
             }
             match event {
                 crate::events::RuntimeEvent::RunletTransport { available: true } => {
-                    deadline = Some(
-                        tokio::time::Instant::now() + crate::runlet_progress::transport::LEASE,
-                    );
+                    deadline =
+                        Some(tokio::time::Instant::now() + crate::diagnostic_transport::LEASE);
                     continue;
                 }
                 crate::events::RuntimeEvent::RunletTransport { available: false } => {
@@ -2017,8 +2011,7 @@ async fn forward_stderr(
                 _ => {}
             }
             if deadline.is_some() {
-                deadline =
-                    Some(tokio::time::Instant::now() + crate::runlet_progress::transport::LEASE);
+                deadline = Some(tokio::time::Instant::now() + crate::diagnostic_transport::LEASE);
             }
             if event.forward_from_child() {
                 if let crate::events::RuntimeEvent::SubagentStateChanged {
@@ -2560,12 +2553,7 @@ mod tests {
 
     #[test]
     fn nested_runtime_events_are_not_forwarded_as_parent_events() {
-        let event = crate::events::RuntimeEvent::ChildStarted {
-            call: "subagent-call:compose:shell".into(),
-            tool: "shell".into(),
-            summary: "inspect".into(),
-            at: 0,
-        };
+        let event = crate::events::RuntimeEvent::RunletTransport { available: true };
         let line = format!(
             "{}{}",
             crate::events::EVENT_MARKER,
@@ -4835,11 +4823,8 @@ for line in sys.stdin:
                     serde_json::to_string(&RuntimeEvent::RunletTransport { available: true })
                         .unwrap()
                 );
-                let started = RuntimeEvent::ChildStarted {
-                    call: "parent:compose:0".into(),
-                    tool: "shell".into(),
-                    summary: "working".into(),
-                    at: 1,
+                let started = RuntimeEvent::SubagentDescendantsRemoved {
+                    ancestor_id: "parent".into(),
                 };
                 let start = format!(
                     "{EVENT_MARKER}{}\n",
@@ -4861,7 +4846,7 @@ for line in sys.stdin:
                     );
                     writer.write_all(reset.as_bytes()).await.unwrap();
                 } else {
-                    tokio::time::advance(crate::runlet_progress::transport::LEASE).await;
+                    tokio::time::advance(crate::diagnostic_transport::LEASE).await;
                 }
                 let reset = match rx.recv().await.unwrap() {
                     ForwardedStderr::RuntimeLine(line) => crate::events::parse(&line).unwrap(),

src/runlet_progress/transport.rs → src/diagnostic_transport.rs

@@ -1,6 +1,5 @@
 //! One process-owned blocking writer, never joined by an execution future.
 //! Publication is bounded and nonblocking, including cancellation/Drop paths.
-use super::Progress;
 use crate::events::{EVENT_MARKER, RuntimeEvent};
 use std::{
     io::{self, Write},
@@ -41,7 +40,7 @@ impl Transport {
         let diagnostics_lost = Arc::new(AtomicBool::new(false));
         let worker_loss = diagnostics_lost.clone();
         std::thread::Builder::new()
-            .name("runlet-diagnostics".into())
+            .name("kit-diagnostics".into())
             .spawn(move || {
                 // Guard invalidates publication on success, error, or unwind. No IO
                 // in its destructor and no restart that could reuse stale evidence.
@@ -54,10 +53,6 @@ impl Transport {
             diagnostics_lost,
         })
     }
-    pub(crate) fn publish(&self, progress: Progress) {
-        self.publish_event(&RuntimeEvent::RunletProgress { progress });
-    }
-
     /// Best-effort diagnostics remain available after authoritative loss.
     pub(crate) fn publish_line(&self, line: &str) {
         const TRUNCATED: &str = " [truncated]";
@@ -150,7 +145,7 @@ fn write_loop(
                     Frame::Authoritative(bytes) | Frame::Diagnostic(bytes) => bytes,
                 };
                 writer.write_all(&bytes)?;
-                // Busy legacy diagnostic traffic must not starve the lease.
+                // Busy diagnostic traffic must not starve the lease.
                 if !disabled.load(Ordering::Acquire) && heartbeat.elapsed() >= HEARTBEAT {
                     transport_status(&mut writer, runtime_events, true)?;
                     heartbeat = Instant::now();
@@ -183,11 +178,6 @@ fn write_frame(writer: &mut impl Write, event: &RuntimeEvent) -> io::Result<()>
 }
 
 fn encode_frame(event: &RuntimeEvent) -> io::Result<Vec<u8>> {
-    if let RuntimeEvent::RunletProgress { progress } = event
-        && !progress.bounded()
-    {
-        return Err(io::Error::other("invalid progress metadata"));
-    }
     // A bounded writer, not an unbounded serialization followed by a size check.
     let mut frame = vec![0; MAX_FRAME_BYTES];
     let len = {

src/runlet_progress/transport/tests.rs → src/diagnostic_transport/tests.rs

@@ -6,21 +6,8 @@
     clippy::disallowed_macros
 )]
 use super::*;
-use crate::runlet_progress::Change;
 use std::io::{BufRead, BufReader, Read};
 
-fn progress() -> Progress {
-    Progress {
-        owner: "parent".into(),
-        incarnation: 1,
-        sequence: 0,
-        change: Change::Started {
-            digest: "a".repeat(64),
-            healed: false,
-        },
-    }
-}
-
 #[cfg(unix)]
 #[test]
 fn stalled_writer_loss_resets_after_drain_and_never_resumes() {
@@ -40,14 +27,15 @@ fn stalled_writer_loss_resets_after_drain_and_never_resumes() {
     writer.set_nonblocking(false).unwrap();
     let transport = Transport::start(writer, 2, true).unwrap();
     for _ in 0..4 {
-        transport.publish_event(&RuntimeEvent::ChildFinished {
-            call: "parent:compose:0".into(),
-            tool: "shell".into(),
+        transport.publish_event(&RuntimeEvent::CompactionFinished {
+            reason: "test".into(),
             ok: true,
-            summary: "done".into(),
+            compacted: true,
             millis: 1,
         });
-        transport.publish(progress());
+        transport.publish_event(&RuntimeEvent::SubagentDescendantsRemoved {
+            ancestor_id: "parent".into(),
+        });
     }
     assert!(transport.disabled.load(Ordering::Acquire));
     reader
@@ -68,7 +56,9 @@ fn stalled_writer_loss_resets_after_drain_and_never_resumes() {
         crate::events::parse(line.trim_end()),
         Some(RuntimeEvent::RunletTransport { available: false })
     );
-    transport.publish(progress());
+    transport.publish_event(&RuntimeEvent::SubagentDescendantsRemoved {
+        ancestor_id: "parent".into(),
+    });
     drop(transport);
     line.clear();
     assert_eq!(reader.read_line(&mut line).unwrap(), 0);
@@ -114,7 +104,9 @@ fn writer_error_and_unwind_fail_closed() {
             diagnostics_lost: Arc::new(AtomicBool::new(false)),
         };
         assert!(transport.disabled.load(Ordering::Acquire));
-        transport.publish(progress());
+        transport.publish_event(&RuntimeEvent::SubagentDescendantsRemoved {
+            ancestor_id: "parent".into(),
+        });
     }
 }
 
@@ -135,12 +127,11 @@ fn last_sender_disconnect_finishes_transport() {
 
 #[cfg(unix)]
 #[test]
-fn lifecycle_frames_share_queue_and_oversize_loss_invalidates_progress() {
-    let event = RuntimeEvent::ChildFinished {
-        call: "owner:compose:0".into(),
-        tool: "shell".into(),
+fn lifecycle_frames_share_queue_and_oversize_loss_invalidates_lifecycle() {
+    let event = RuntimeEvent::CompactionFinished {
+        reason: "test".into(),
         ok: true,
-        summary: "done".into(),
+        compacted: true,
         millis: 1,
     };
     let (writer, mut reader) = std::os::unix::net::UnixStream::pair().unwrap();
@@ -166,7 +157,9 @@ fn lifecycle_frames_share_queue_and_oversize_loss_invalidates_progress() {
         session_id: "x".repeat(MAX_FRAME_BYTES),
     });
     assert!(transport.disabled.load(Ordering::Acquire));
-    transport.publish(progress());
+    transport.publish_event(&RuntimeEvent::SubagentDescendantsRemoved {
+        ancestor_id: "parent".into(),
+    });
     transport.publish_line("later child error");
     drop(transport);
     wire.clear();