diff --git a/crates/protocol/src/subscription.rs b/crates/protocol/src/subscription.rs
index 71f8cf2d..053f7810 100644
--- a/crates/protocol/src/subscription.rs
+++ b/crates/protocol/src/subscription.rs
@@ -554,6 +554,8 @@ pub struct SubscriptionWorker {
     /// Producer-owned monotonic revision for this Worker subject.
     pub subject_revision: u64,
     pub state: SubscriptionWorkerState,
+    #[serde(default)]
+    pub has_running_internal_workers: bool,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub workspace_id: Option<String>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -796,6 +798,7 @@ mod tests {
             runtime_id: None,
             subject_revision: 0,
             state: SubscriptionWorkerState::Idle,
+            has_running_internal_workers: false,
             workspace_id: Some("workspace-1".to_string()),
             display_name: Some(format!("Worker {value}")),
             profile: Some("builtin:coder".to_string()),
diff --git a/crates/worker-runtime/src/runtime.rs b/crates/worker-runtime/src/runtime.rs
index b97c5b58..441e72b0 100644
--- a/crates/worker-runtime/src/runtime.rs
+++ b/crates/worker-runtime/src/runtime.rs
@@ -335,6 +335,7 @@ impl Runtime {
         for (worker_id, worker) in &mut state.workers {
             if worker.status.is_active() {
                 worker.status = WorkerStatus::Stopped;
+                worker.internal_workers.clear();
                 stopped.push(*worker_id);
             }
         }
@@ -574,6 +575,7 @@ impl Runtime {
                 run_generation: 1,
                 working_directory: None,
                 execution_handle: None,
+                internal_workers: BTreeMap::new(),
             };
             state.workers.insert(worker_id, record);
             state.persist_runtime_snapshot()?;
@@ -1471,7 +1473,8 @@ impl Runtime {
         let mut state = self.lock()?;
         state.ensure_worker_ref(worker_ref)?;
         let status_changed = state.project_protocol_event_to_status(worker_ref, &payload);
-        if status_changed {
+        let activity_changed = state.project_internal_worker_activity(worker_ref, &payload);
+        if status_changed || activity_changed {
             state.publish_worker_upsert(worker_ref.worker_id)?;
         }
         let event = state.push_worker_observation_event(worker_ref.clone(), payload);
@@ -1528,6 +1531,7 @@ impl Runtime {
         let worker = state.worker_mut(worker_ref)?;
         worker.status = status;
         worker.execution_handle = None;
+        worker.internal_workers.clear();
         let status = worker.status;
         state.publish_worker_upsert(worker_ref.worker_id)?;
         state.persist_runtime_snapshot()?;
@@ -1940,6 +1944,7 @@ impl RuntimeState {
                     run_generation: worker.run_generation,
                     working_directory: worker.working_directory,
                     execution_handle: None,
+                    internal_workers: BTreeMap::new(),
                 },
             );
         }
@@ -2260,6 +2265,10 @@ impl RuntimeState {
                 .copied()
                 .unwrap_or(0),
             state: subscription_worker_state(worker.status),
+            has_running_internal_workers: worker
+                .internal_workers
+                .values()
+                .any(|worker| worker.status == protocol::WorkerStatus::Running),
             workspace_id: worker.workspace_id.clone(),
             display_name: worker.request.display_name.clone(),
             profile,
@@ -2402,6 +2411,7 @@ impl RuntimeState {
         let worker = self.worker_mut(worker_ref)?;
         worker.execution_handle = None;
         worker.status = WorkerStatus::Stopped;
+        worker.internal_workers.clear();
         self.publish_worker_upsert(worker_ref.worker_id)?;
         self.persist_runtime_snapshot()?;
         Ok(())
@@ -2455,7 +2465,134 @@ impl RuntimeState {
         event
     }
 
-    #[cfg(feature = "ws-server")]
+    fn internal_worker_snapshot_statuses(
+        statuses: &mut BTreeMap<String, InternalWorkerActivity>,
+        snapshot: &protocol::InternalWorkerSnapshot,
+    ) {
+        statuses.insert(
+            snapshot.worker.session_id.clone(),
+            InternalWorkerActivity {
+                status: snapshot.status,
+                parent_session_id: snapshot.worker.parent_session_id.clone(),
+            },
+        );
+        for child in &snapshot.internal_workers {
+            Self::internal_worker_snapshot_statuses(statuses, child);
+        }
+    }
+
+    fn remove_internal_worker_subtree(
+        statuses: &mut BTreeMap<String, InternalWorkerActivity>,
+        root_session_id: &str,
+    ) {
+        let mut removed = vec![root_session_id.to_string()];
+        while let Some(parent_session_id) = removed.pop() {
+            let children = statuses
+                .iter()
+                .filter_map(|(session_id, worker)| {
+                    (worker.parent_session_id.as_deref() == Some(parent_session_id.as_str()))
+                        .then(|| session_id.clone())
+                })
+                .collect::<Vec<_>>();
+            statuses.remove(&parent_session_id);
+            removed.extend(children);
+        }
+    }
+
+    fn project_internal_worker_event(
+        statuses: &mut BTreeMap<String, InternalWorkerActivity>,
+        worker: &protocol::InternalWorkerRef,
+        event: &protocol::Event,
+    ) {
+        match event {
+            protocol::Event::Snapshot {
+                status,
+                internal_workers,
+                ..
+            } => {
+                Self::remove_internal_worker_subtree(statuses, &worker.session_id);
+                statuses.insert(
+                    worker.session_id.clone(),
+                    InternalWorkerActivity {
+                        status: *status,
+                        parent_session_id: worker.parent_session_id.clone(),
+                    },
+                );
+                for child in internal_workers {
+                    Self::internal_worker_snapshot_statuses(statuses, child);
+                }
+            }
+            protocol::Event::InternalWorker {
+                worker: nested_worker,
+                event,
+                ..
+            } => Self::project_internal_worker_event(statuses, nested_worker, event),
+            protocol::Event::Status { status } => {
+                statuses.insert(
+                    worker.session_id.clone(),
+                    InternalWorkerActivity {
+                        status: *status,
+                        parent_session_id: worker.parent_session_id.clone(),
+                    },
+                );
+            }
+            protocol::Event::RunEnd { result } => {
+                let status = match result {
+                    protocol::RunResult::Paused => protocol::WorkerStatus::Paused,
+                    protocol::RunResult::Finished
+                    | protocol::RunResult::LimitReached
+                    | protocol::RunResult::RolledBack => protocol::WorkerStatus::Idle,
+                };
+                statuses.insert(
+                    worker.session_id.clone(),
+                    InternalWorkerActivity {
+                        status,
+                        parent_session_id: worker.parent_session_id.clone(),
+                    },
+                );
+            }
+            _ => {}
+        }
+    }
+
+    fn update_internal_worker_activity(
+        statuses: &mut BTreeMap<String, InternalWorkerActivity>,
+        event: &protocol::Event,
+    ) -> bool {
+        let was_running = statuses
+            .values()
+            .any(|worker| worker.status == protocol::WorkerStatus::Running);
+        match event {
+            protocol::Event::Snapshot {
+                internal_workers, ..
+            } => {
+                statuses.clear();
+                for child in internal_workers {
+                    Self::internal_worker_snapshot_statuses(statuses, child);
+                }
+            }
+            protocol::Event::InternalWorker { worker, event, .. } => {
+                Self::project_internal_worker_event(statuses, worker, event);
+            }
+            _ => {}
+        }
+        let is_running = statuses
+            .values()
+            .any(|worker| worker.status == protocol::WorkerStatus::Running);
+        was_running != is_running
+    }
+
+    fn project_internal_worker_activity(
+        &mut self,
+        worker_ref: &WorkerRef,
+        event: &protocol::Event,
+    ) -> bool {
+        let Some(worker) = self.workers.get_mut(&worker_ref.worker_id) else {
+            return false;
+        };
+        Self::update_internal_worker_activity(&mut worker.internal_workers, event)
+    }
+
     fn project_protocol_event_to_status(
         &mut self,
         worker_ref: &WorkerRef,
@@ -2498,6 +2635,12 @@ impl RuntimeState {
     }
 }
 
+#[derive(Debug, Clone)]
+struct InternalWorkerActivity {
+    status: protocol::WorkerStatus,
+    parent_session_id: Option<String>,
+}
+
 #[derive(Debug)]
 struct WorkerRecord {
     worker_ref: WorkerRef,
@@ -2508,6 +2651,7 @@ struct WorkerRecord {
     run_generation: u64,
     working_directory: Option<CatalogWorkingDirectoryStatus>,
     execution_handle: Option<WorkerExecutionHandle>,
+    internal_workers: BTreeMap<String, InternalWorkerActivity>,
 }
 
 impl WorkerRecord {
@@ -2730,6 +2874,126 @@ mod tests {
     use std::sync::atomic::{AtomicU64, Ordering};
     use std::sync::{Arc, Mutex};
 
+    fn internal_worker_ref(
+        session_id: &str,
+        parent_session_id: Option<&str>,
+    ) -> protocol::InternalWorkerRef {
+        protocol::InternalWorkerRef {
+            session_id: session_id.to_string(),
+            parent_session_id: parent_session_id.map(str::to_string),
+            name: session_id.to_string(),
+            kind: protocol::InternalWorkerKind::SubWorker,
+        }
+    }
+
+    fn internal_worker_status_event(
+        worker: protocol::InternalWorkerRef,
+        status: protocol::WorkerStatus,
+    ) -> protocol::Event {
+        protocol::Event::InternalWorker {
+            worker,
+            revision: 1,
+            event: Box::new(protocol::Event::Status { status }),
+        }
+    }
+
+    #[test]
+    fn internal_worker_activity_tracks_running_children_independently() {
+        let mut activity = BTreeMap::new();
+        assert!(RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &internal_worker_status_event(
+                internal_worker_ref("child-a", None),
+                protocol::WorkerStatus::Running,
+            ),
+        ));
+        assert!(!RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &internal_worker_status_event(
+                internal_worker_ref("child-b", None),
+                protocol::WorkerStatus::Running,
+            ),
+        ));
+        assert!(!RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &internal_worker_status_event(
+                internal_worker_ref("child-a", None),
+                protocol::WorkerStatus::Idle,
+            ),
+        ));
+        assert!(RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &internal_worker_status_event(
+                internal_worker_ref("child-b", None),
+                protocol::WorkerStatus::Idle,
+            ),
+        ));
+    }
+
+    #[test]
+    fn nested_internal_worker_activity_reaches_the_parent_projection() {
+        let mut activity = BTreeMap::new();
+        let direct_child = internal_worker_ref("child", None);
+        let nested_running = protocol::Event::InternalWorker {
+            worker: direct_child.clone(),
+            revision: 1,
+            event: Box::new(internal_worker_status_event(
+                internal_worker_ref("grandchild", Some("child")),
+                protocol::WorkerStatus::Running,
+            )),
+        };
+        assert!(RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &nested_running,
+        ));
+
+        let nested_idle = protocol::Event::InternalWorker {
+            worker: direct_child,
+            revision: 2,
+            event: Box::new(internal_worker_status_event(
+                internal_worker_ref("grandchild", Some("child")),
+                protocol::WorkerStatus::Idle,
+            )),
+        };
+        assert!(RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &nested_idle,
+        ));
+    }
+
+    #[test]
+    fn parent_snapshot_replaces_stale_internal_worker_activity() {
+        let mut activity = BTreeMap::new();
+        RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &internal_worker_status_event(
+                internal_worker_ref("child-a", None),
+                protocol::WorkerStatus::Running,
+            ),
+        );
+        let snapshot = protocol::Event::Snapshot {
+            entries: Vec::new(),
+            greeting: protocol::Greeting {
+                worker_name: "parent".to_string(),
+                cwd: "/tmp".to_string(),
+                provider: "test".to_string(),
+                model: "test".to_string(),
+                scope_summary: String::new(),
+                tools: Vec::new(),
+                context_window: 0,
+                context_tokens: 0,
+            },
+            status: protocol::WorkerStatus::Idle,
+            in_flight: protocol::InFlightSnapshot::default(),
+            internal_workers: Vec::new(),
+        };
+        assert!(RuntimeState::update_internal_worker_activity(
+            &mut activity,
+            &snapshot,
+        ));
+        assert!(activity.is_empty());
+    }
+
     #[test]
     fn runtime_identity_binding_is_immutable_and_host_owned() {
         let runtime = Runtime::new_memory();
@@ -3083,16 +3347,75 @@ mod tests {
             payload => panic!("unexpected subscription payload: {payload:?}"),
         }
 
-        runtime.stop_runtime().unwrap();
+        runtime
+            .observe_worker_event(
+                &created.worker_ref,
+                internal_worker_status_event(
+                    internal_worker_ref("child-live", None),
+                    protocol::WorkerStatus::Running,
+                ),
+            )
+            .unwrap();
         let update = receive_subscription_update(&mut subscription).unwrap();
         assert_eq!(update.subject_revision, 2);
         match update.payload {
             SubscriptionEventPayload::WorkerUpserted { worker } => {
-                assert_eq!(worker.worker_id.as_str(), created.worker_id.to_string());
-                assert_eq!(worker.state, SubscriptionWorkerState::Stopped);
+                assert_eq!(worker.state, SubscriptionWorkerState::Idle);
+                assert!(worker.has_running_internal_workers);
             }
             payload => panic!("unexpected subscription payload: {payload:?}"),
         }
+
+        runtime
+            .observe_worker_event(
+                &created.worker_ref,
+                internal_worker_status_event(
+                    internal_worker_ref("child-live", None),
+                    protocol::WorkerStatus::Idle,
+                ),
+            )
+            .unwrap();
+        let update = receive_subscription_update(&mut subscription).unwrap();
+        assert_eq!(update.subject_revision, 3);
+        match update.payload {
+            SubscriptionEventPayload::WorkerUpserted { worker } => {
+                assert_eq!(worker.state, SubscriptionWorkerState::Idle);
+                assert!(!worker.has_running_internal_workers);
+            }
+            payload => panic!("unexpected subscription payload: {payload:?}"),
+        }
+
+        runtime
+            .observe_worker_event(
+                &created.worker_ref,
+                internal_worker_status_event(
+                    internal_worker_ref("child-live", None),
+                    protocol::WorkerStatus::Running,
+                ),
+            )
+            .unwrap();
+        let update = receive_subscription_update(&mut subscription).unwrap();
+        assert_eq!(update.subject_revision, 4);
+        match update.payload {
+            SubscriptionEventPayload::WorkerUpserted { worker } => {
+                assert_eq!(worker.state, SubscriptionWorkerState::Idle);
+                assert!(worker.has_running_internal_workers);
+            }
+            payload => panic!("unexpected subscription payload: {payload:?}"),
+        }
+
+        runtime.stop_worker(&created.worker_ref, None).unwrap();
+        let update = receive_subscription_update(&mut subscription).unwrap();
+        assert_eq!(update.subject_revision, 5);
+        match update.payload {
+            SubscriptionEventPayload::WorkerUpserted { worker } => {
+                assert_eq!(worker.worker_id.as_str(), created.worker_id.to_string());
+                assert_eq!(worker.state, SubscriptionWorkerState::Stopped);
+                assert!(!worker.has_running_internal_workers);
+            }
+            payload => panic!("unexpected subscription payload: {payload:?}"),
+        }
+        runtime.stop_runtime().unwrap();
     }
 
     #[test]
diff --git a/web/workspace/src/lib/generated/protocol.ts b/web/workspace/src/lib/generated/protocol.ts
index 471f4dab..25fc8cf2 100644
--- a/web/workspace/src/lib/generated/protocol.ts
+++ b/web/workspace/src/lib/generated/protocol.ts
@@ -128,7 +128,7 @@ runtime_id?: string | null,
 /**
  * Producer-owned monotonic revision for this Worker subject.
  */
-subject_revision: number, state: SubscriptionWorkerState, workspace_id?: string | null, display_name?: string | null, profile?: string | null, repository_id?: string | null, working_directory_id?: SubscriptionWorkdirId | null, };
+subject_revision: number, state: SubscriptionWorkerState, has_running_internal_workers: boolean, workspace_id?: string | null, display_name?: string | null, profile?: string | null, repository_id?: string | null, working_directory_id?: SubscriptionWorkdirId | null, };
 
 export type SubscriptionWorkdir = { working_directory_id: SubscriptionWorkdirId, repository_id: string, state: string, primary_worker_id?: SubscriptionWorkerId | null, };
 
diff --git a/web/workspace/src/lib/workspace/console/Spinner.svelte b/web/workspace/src/lib/workspace/console/Spinner.svelte
index 620e9b71..21b90518 100644
--- a/web/workspace/src/lib/workspace/console/Spinner.svelte
+++ b/web/workspace/src/lib/workspace/console/Spinner.svelte
@@ -29,7 +29,7 @@
 <style>
   .spinner {
     display: inline-flex;
-    color: var(--accent);
+    color: var(--spinner-color, var(--accent));
     line-height: 1;
   }
 </style>
diff --git a/web/workspace/src/lib/workspace/sidebar/WorkersNavSection.svelte b/web/workspace/src/lib/workspace/sidebar/WorkersNavSection.svelte
index 584add88..b2fffcd6 100644
--- a/web/workspace/src/lib/workspace/sidebar/WorkersNavSection.svelte
+++ b/web/workspace/src/lib/workspace/sidebar/WorkersNavSection.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+  import Spinner from '$lib/workspace/console/Spinner.svelte';
   import { workerConsoleHref } from '$lib/workspace/console/model';
   import {
     workspaceWorkersStore,
@@ -76,10 +77,12 @@
             aria-current={currentPath === href ? 'page' : undefined}
           >
             <span class="worker-status-indicator">
-              {#if worker.state === 'idle'}
+              {#if worker.state === 'running'}
+                <span class="worker-status-spinner"><Spinner label="Running" /></span>
+              {:else if worker.has_running_internal_workers}
+                <span class="worker-status-spinner is-subworker"><Spinner label="SubWorker running" /></span>
+              {:else if worker.state === 'idle'}
                 <span class="worker-status-dot" aria-label="Idle"></span>
-              {:else if worker.state === 'running'}
-                <span class="worker-status-spinner" aria-label="Running"></span>
               {/if}
             </span>
             <span class="worker-nav-label">{worker.display_name || worker.label}</span>
diff --git a/web/workspace/src/lib/workspace/sidebar/sidebar.css b/web/workspace/src/lib/workspace/sidebar/sidebar.css
index 17a8b49e..bb8ecb84 100644
--- a/web/workspace/src/lib/workspace/sidebar/sidebar.css
+++ b/web/workspace/src/lib/workspace/sidebar/sidebar.css
@@ -267,12 +267,17 @@
     background: var(--success);
   }
   .worker-status-spinner {
-    width: 0.625rem;
-    height: 0.625rem;
-    border: 0.125rem solid color-mix(in oklch, var(--accent) 25%, transparent);
-    border-top-color: var(--accent);
-    border-radius: 50%;
-    animation: worker-status-spin 0.8s linear infinite;
+    --spinner-color: var(--success);
+
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 0.75rem;
+    font-size: 0.7rem;
+    line-height: 1;
+  }
+  .worker-status-spinner.is-subworker {
+    --spinner-color: var(--tui-magenta);
   }
   .worker-nav-label {
     grid-column: 2;
@@ -339,16 +344,6 @@
   .worker-overflow-toggle[aria-expanded="true"] .worker-overflow-chevron {
     transform: rotate(180deg);
   }
-  @keyframes worker-status-spin {
-    to {
-      transform: rotate(360deg);
-    }
-  }
-  @media (prefers-reduced-motion: reduce) {
-    .worker-status-spinner {
-      animation: none;
-    }
-  }
 
   @media (max-width: 760px) {
     .sidebar-frame,
diff --git a/web/workspace/src/lib/workspace/sidebar/worker-subscription.test.ts b/web/workspace/src/lib/workspace/sidebar/worker-subscription.test.ts
index 8b6d91bf..5b0d4c3d 100644
--- a/web/workspace/src/lib/workspace/sidebar/worker-subscription.test.ts
+++ b/web/workspace/src/lib/workspace/sidebar/worker-subscription.test.ts
@@ -20,6 +20,7 @@ function worker(runtimeId: string, workerId: string, revision: number): Subscrip
     runtime_id: runtimeId,
     subject_revision: revision,
     state: 'idle',
+    has_running_internal_workers: false,
     workspace_id: 'workspace-test',
     display_name: null,
     profile: null,
diff --git a/web/workspace/src/lib/workspace/sidebar/worker-subscription.ts b/web/workspace/src/lib/workspace/sidebar/worker-subscription.ts
index 7f3c72d6..d7927834 100644
--- a/web/workspace/src/lib/workspace/sidebar/worker-subscription.ts
+++ b/web/workspace/src/lib/workspace/sidebar/worker-subscription.ts
@@ -11,6 +11,7 @@ import type { Worker } from './types';
 export type SidebarWorker = Worker & {
   repository_id: string | null;
   working_directory_id: string | null;
+  has_running_internal_workers: boolean;
 };
 
 export type WorkspaceWorkersState = {
@@ -96,6 +97,7 @@ function projectWorker(worker: SubscriptionWorker): SidebarWorker {
     },
     repository_id: worker.repository_id ?? null,
     working_directory_id: worker.working_directory_id ?? null,
+    has_running_internal_workers: worker.has_running_internal_workers,
     working_directory: null,
     diagnostics: [],
   };
diff --git a/web/workspace/tests/console-spinner-source.test.ts b/web/workspace/tests/console-spinner-source.test.ts
index 8354bb68..a4392077 100644
--- a/web/workspace/tests/console-spinner-source.test.ts
+++ b/web/workspace/tests/console-spinner-source.test.ts
@@ -28,6 +28,62 @@ Deno.test("Console spinner wraps a reusable timed sequence loop", async () => {
   assert(spinner.includes("SequenceLoop"), "Spinner should wrap SequenceLoop");
 });
 
+Deno.test("sidebar running status reuses the green symbol spinner", async () => {
+  const sidebar = await Deno.readTextFile(
+    new URL(
+      "../src/lib/workspace/sidebar/WorkersNavSection.svelte",
+      import.meta.url,
+    ),
+  );
+  const sidebarCss = await Deno.readTextFile(
+    new URL(
+      "../src/lib/workspace/sidebar/sidebar.css",
+      import.meta.url,
+    ),
+  );
+
+  assert(
+    sidebar.includes(
+      "import Spinner from '$lib/workspace/console/Spinner.svelte'",
+    ),
+    "Workers sidebar should import the reusable symbol Spinner",
+  );
+  assert(
+    sidebar.includes('<Spinner label="Running" />'),
+    "running Workers should render the reusable symbol Spinner",
+  );
+  assert(
+    sidebarCss.includes("--spinner-color: var(--success)"),
+    "sidebar spinner should use the green success token",
+  );
+  assert(
+    sidebar.indexOf("worker.state === 'running'") <
+      sidebar.indexOf("worker.has_running_internal_workers"),
+    "parent running state should keep the green Spinner priority",
+  );
+  assert(
+    sidebar.indexOf("worker.has_running_internal_workers") <
+      sidebar.indexOf("worker.state === 'idle'"),
+    "SubWorker activity should replace the idle dot with the purple Spinner",
+  );
+  assert(
+    sidebar.includes("worker.has_running_internal_workers"),
+    "idle parents should render SubWorker activity from the Workspace projection",
+  );
+  assert(
+    sidebar.includes('<Spinner label="SubWorker running" />'),
+    "running SubWorkers should use the reusable symbol Spinner",
+  );
+  assert(
+    sidebarCss.includes("--spinner-color: var(--tui-magenta)"),
+    "SubWorker spinner should use the purple TUI token",
+  );
+  assert(
+    !sidebarCss.includes("@keyframes worker-status-spin"),
+    "legacy rotating ring spinner should be removed",
+  );
+});
+
 Deno.test("running status is Composer-side above mini Tasks", async () => {
   const page = await Deno.readTextFile(
     new URL(