diff --git a/app/src/pages/Conversations.tsx b/app/src/pages/Conversations.tsx
index 5ff0f849e..dfa4a5fb1 100644
--- a/app/src/pages/Conversations.tsx
+++ b/app/src/pages/Conversations.tsx
@@ -293,16 +293,22 @@ const Conversations = ({ variant = 'page', composer = 'text' }: ConversationsPro
         //   return;
         // }
         const threadStateForSelect = store.getState().thread;
-        if (data.threads.length > 0) {
+        // Worker/subagent threads are hidden from the conversation list
+        // (see tinyhumansai/openhuman#1624). Match the sidebar filter here so
+        // initial/resume selection can't auto-pick a hidden thread and leave
+        // the UI showing a thread that isn't in the list.
+        const visibleThreads = data.threads.filter(t => !t.parentThreadId);
+        if (visibleThreads.length > 0) {
           // Prefer the thread the user was last viewing (persisted across
           // reloads via redux-persist on the `thread` slice). Only fall
           // through to "most recent" if that thread no longer exists
-          // server-side (deleted, purged, or different user).
+          // server-side (deleted, purged, or different user) — or is now
+          // hidden because it's a worker thread.
           const persistedId = threadStateForSelect.selectedThreadId;
           const resumeId =
-            persistedId && data.threads.some(t => t.id === persistedId)
+            persistedId && visibleThreads.some(t => t.id === persistedId)
               ? persistedId
-              : data.threads[0].id;
+              : visibleThreads[0].id;
           dispatch(setSelectedThread(resumeId));
           void dispatch(loadThreadMessages(resumeId));
         } else {
@@ -940,6 +946,10 @@ const Conversations = ({ variant = 'page', composer = 'text' }: ConversationsPro
 
   const filteredThreads = useMemo(() => {
     const base = threads.filter(t => {
+      // Hide worker/subagent threads from the conversation list. They are
+      // currently surfaced inline inside the parent thread via WorkerThreadRefCard.
+      // A dedicated showcase is tracked in tinyhumansai/openhuman#1624.
+      if (t.parentThreadId) return false;
       if (selectedLabel === 'all') return true;
       return t.labels?.includes(selectedLabel);
     });
diff --git a/src/openhuman/tools/impl/agent/spawn_subagent.rs b/src/openhuman/tools/impl/agent/spawn_subagent.rs
index d0eeb20cd..ae5aaa284 100644
--- a/src/openhuman/tools/impl/agent/spawn_subagent.rs
+++ b/src/openhuman/tools/impl/agent/spawn_subagent.rs
@@ -128,7 +128,7 @@ impl Tool for SpawnSubagentTool {
                 },
                 "dedicated_thread": {
                     "type": "boolean",
-                    "description": "Default `false`. Set `true` ONLY for long, complex sub-tasks where the parent thread should not be flooded with sub-agent output. The sub-agent's prompt and final summary land in a fresh worker-labeled thread the user can open from the thread list, and the parent receives a compact reference (worker thread id + brief summary) instead of the full transcript. Worker threads cannot themselves spawn another worker (sub-agents never see this tool), so this is a one-level-deep escape hatch."
+                    "description": "Temporarily disabled (see tinyhumansai/openhuman#1624). Passing `true` causes this tool to return an explicit error. Omit the field or pass `false` until the worker-thread UI surface lands."
                 }
             }
         })
@@ -166,10 +166,25 @@ impl Tool for SpawnSubagentTool {
             .map(|s| s.trim().to_string())
             .filter(|s| !s.is_empty());
 
-        let dedicated_thread = args
+        // Worker-thread spawning is temporarily disabled until a proper UI
+        // showcase lands (see tinyhumansai/openhuman#1624). Return an
+        // explicit error when callers request a dedicated thread so the
+        // behaviour is observable rather than silently downgraded.
+        let dedicated_thread_requested = args
             .get("dedicated_thread")
             .and_then(|v| v.as_bool())
             .unwrap_or(false);
+        if dedicated_thread_requested {
+            log::debug!(
+                "[spawn_subagent] dedicated_thread requested but temporarily \
+                 disabled (see tinyhumansai/openhuman#1624); rejecting call"
+            );
+            return Ok(ToolResult::error(
+                "spawn_subagent: `dedicated_thread` is temporarily disabled \
+                 (see tinyhumansai/openhuman#1624); retry without it.",
+            ));
+        }
+        let dedicated_thread = false;
 
         // ── Validation ─────────────────────────────────────────────────
         if agent_id.is_empty() {
diff --git a/src/openhuman/tools/orchestrator_tools.rs b/src/openhuman/tools/orchestrator_tools.rs
index 77e162861..3a94f2055 100644
--- a/src/openhuman/tools/orchestrator_tools.rs
+++ b/src/openhuman/tools/orchestrator_tools.rs
@@ -29,7 +29,11 @@ use crate::openhuman::agent::harness::definition::{
 };
 use crate::openhuman::context::prompt::ConnectedIntegration;
 
-use super::{ArchetypeDelegationTool, SkillDelegationTool, SpawnWorkerThreadTool, Tool};
+// SpawnWorkerThreadTool import kept commented while the worker-thread spawn is
+// temporarily disabled (see tinyhumansai/openhuman#1624).
+#[allow(unused_imports)]
+use super::SpawnWorkerThreadTool;
+use super::{ArchetypeDelegationTool, SkillDelegationTool, Tool};
 
 /// Synthesise the delegation tool list for an agent based on its
 /// declarative `subagents` field.
@@ -66,9 +70,12 @@ pub fn collect_orchestrator_tools(
     let mut tools: Vec<Box<dyn Tool>> = Vec::new();
 
     // Orchestrator-only tool: spawn_worker_thread.
-    if definition.id == "orchestrator" {
-        tools.push(Box::new(SpawnWorkerThreadTool::new()));
-    }
+    // Temporarily disabled — worker threads do not yet have a proper UI
+    // showcase (see tinyhumansai/openhuman#1624). Re-enable once the
+    // dedicated worker-thread surface lands.
+    // if definition.id == "orchestrator" {
+    //     tools.push(Box::new(SpawnWorkerThreadTool::new()));
+    // }
 
     for entry in &definition.subagents {
         match entry {
@@ -298,7 +305,9 @@ mod tests {
         assert_eq!(
             names,
             vec![
-                "spawn_worker_thread",   // orchestrator-only, prepended in collect_orchestrator_tools
+                // `spawn_worker_thread` is temporarily disabled — see
+                // tinyhumansai/openhuman#1624. Re-add the leading entry when
+                // the registration in `collect_orchestrator_tools` is restored.
                 "research",              // researcher's delegate_name override
                 "delegate_archivist",    // archivist has no delegate_name → default
                 "delegate_gmail",
@@ -329,10 +338,8 @@ mod tests {
         let reg = registry_with_targets();
         let tools = collect_orchestrator_tools(&orch, &reg, &[]);
         let names: Vec<&str> = tools.iter().map(|t| t.name()).collect();
-        assert_eq!(
-            names,
-            vec!["spawn_worker_thread", "research", "delegate_archivist"]
-        );
+        // `spawn_worker_thread` is temporarily disabled — see #1624.
+        assert_eq!(names, vec!["research", "delegate_archivist"]);
     }
 
     /// An AgentId entry that points at an id not present in the registry
@@ -348,7 +355,8 @@ mod tests {
         let reg = registry_with_targets();
         let tools = collect_orchestrator_tools(&orch, &reg, &[]);
         let names: Vec<&str> = tools.iter().map(|t| t.name()).collect();
-        assert_eq!(names, vec!["spawn_worker_thread", "research"]);
+        // `spawn_worker_thread` is temporarily disabled — see #1624.
+        assert_eq!(names, vec!["research"]);
     }
 
     /// An empty `subagents` list should produce zero tools — regular