diff --git a/apps/web/src/components/Sidebar.logic.test.ts b/apps/web/src/components/Sidebar.logic.test.ts
index f6e66a1ac6506..fde82414afa79 100644
--- a/apps/web/src/components/Sidebar.logic.test.ts
+++ b/apps/web/src/components/Sidebar.logic.test.ts
@@ -12,6 +12,8 @@ import {
   getFallbackThreadIdAfterDelete,
   hasUnseenCompletion,
   resolveSidebarRowThreadId,
+  belongsInSidebarWorkingShelf,
+  isSidebarEnvironmentDisconnected,
   orderItemsByPreferredIds,
   pinOrderKeyBetween,
   resolveProjectStatusIndicator,
@@ -1089,6 +1091,38 @@ describe("Working shelf (beta)", () => {
     ).toBe(false);
   });
 
+  it.each([
+    ["connected", true, false],
+    ["connected", false, true],
+    ["connecting", false, false],
+    ["reconnecting", false, true],
+    ["offline", false, true],
+    ["error", false, true],
+    ["unsupported", false, true],
+    ["available", false, true],
+  ] as const)(
+    "lists threads outside the shelf on a %s environment: %s",
+    (phase, shellIsLive, disconnected) => {
+      expect(isSidebarEnvironmentDisconnected(phase, shellIsLive)).toBe(disconnected);
+    },
+  );
+
+  it("lists a running thread outside the shelf while its environment is disconnected", () => {
+    const thread = { ...idle, runtime, environmentId: localEnvironmentId };
+    const shelve = (disconnected: ReadonlyArray<EnvironmentId>, enabled = true) =>
+      belongsInSidebarWorkingShelf(thread, {
+        enabled,
+        disconnectedEnvironmentIds: new Set(disconnected),
+        isWorking: isSidebarThreadWorking,
+      });
+
+    expect(shelve([])).toBe(true);
+    expect(shelve([localEnvironmentId])).toBe(false);
+    expect(shelve([])).toBe(true);
+    expect(shelve([EnvironmentId.make("environment-other")])).toBe(true);
+    expect(shelve([], false)).toBe(false);
+  });
+
   describe("sortInboxThreadsByReturn", () => {
     const thread = (
       id: string,
diff --git a/apps/web/src/components/Sidebar.logic.ts b/apps/web/src/components/Sidebar.logic.ts
index 730a3508bb8cc..0f51d231d333b 100644
--- a/apps/web/src/components/Sidebar.logic.ts
+++ b/apps/web/src/components/Sidebar.logic.ts
@@ -16,6 +16,7 @@ import {
   type ThreadSearchShell,
 } from "@t3tools/client-runtime/state/thread-search";
 import { foldSearchQuery, rankSearchItems, scoreThreadSearch } from "@t3tools/shared/paletteSearch";
+import type { EnvironmentConnectionPhase } from "@t3tools/client-runtime/connection";
 import {
   isListedThreadLineage,
   type ContextMenuItem,
@@ -184,6 +185,29 @@ export function resolveSidebarThreadSection(input: {
   return "active";
 }
 
+// Keep cached placement on the first connection attempt, matching mobile's threadRouteIsHydrating.
+export function isSidebarEnvironmentDisconnected(
+  phase: EnvironmentConnectionPhase,
+  shellIsLive: boolean,
+): boolean {
+  return phase !== "connecting" && (phase !== "connected" || !shellIsLive);
+}
+
+export function belongsInSidebarWorkingShelf<T extends { readonly environmentId: EnvironmentId }>(
+  thread: T,
+  input: {
+    readonly enabled: boolean;
+    readonly disconnectedEnvironmentIds: ReadonlySet<EnvironmentId>;
+    readonly isWorking: (thread: T) => boolean;
+  },
+): boolean {
+  return (
+    input.enabled &&
+    !input.disconnectedEnvironmentIds.has(thread.environmentId) &&
+    input.isWorking(thread)
+  );
+}
+
 const SIDEBAR_MARKER_PREFIX = "sidebar-marker-";
 
 export type SidebarListMarker =
diff --git a/apps/web/src/components/Sidebar.tsx b/apps/web/src/components/Sidebar.tsx
index e6f23149dfedb..2eea84e86f97f 100644
--- a/apps/web/src/components/Sidebar.tsx
+++ b/apps/web/src/components/Sidebar.tsx
@@ -1,3 +1,4 @@
+import { liveShellEnvironmentIdsAtom } from "../state/shell";
 import { attachSidebarTree, SIDEBAR_TREE_PROPS } from "../lib/sidebarTree";
 import { type EnvironmentId, type ScopedProjectRef } from "@t3tools/contracts";
 import type { EnvironmentServerConfig } from "@t3tools/client-runtime/connection";
@@ -138,6 +139,7 @@ import { useNowMinute } from "../hooks/useNowMinute";
 import {
   useEnvironmentIdentities,
   useConnectedEnvironmentIds,
+  useEnvironmentConnectionSummaries,
   useEnvironmentMachines,
   usePrimaryEnvironmentId,
 } from "../state/environments";
@@ -184,6 +186,8 @@ import {
   deleteSelectedThreadEntries,
   filterSidebarProjectScopeItems,
   firstValidTimestampMs,
+  belongsInSidebarWorkingShelf,
+  isSidebarEnvironmentDisconnected,
   isSidebarNestedLinkClick,
   isTrailingDoubleClick,
   orderItemsByPreferredIds,
@@ -351,6 +355,7 @@ interface SidebarThreadPartitionInput {
   readonly workingShelfEnabled: boolean;
   /** Boring mode: folders list active threads by the user's latest message. */
   readonly sortActiveBySend: boolean;
+  readonly disconnectedEnvironmentIds: ReadonlySet<EnvironmentId>;
   // Snooze wakes, the queued-turn grace and the Working shelf's exit grace depend
   // on the clock, so the minute tick, the precise snooze-wake tick and the inbox
   // tracker's expiry version are inputs: a new key repartitions.
@@ -432,6 +437,18 @@ function useSidebarThreads(input: {
   // Folders already separate the work, so boring mode has no Working shelf.
   const workingShelfEnabled =
     useClientSettings((s) => s.sidebarWorkingShelfEnabled) && folderGroups === null;
+  const environmentConnections = useEnvironmentConnectionSummaries();
+  const liveShellEnvironmentIds = useAtomValue(liveShellEnvironmentIdsAtom);
+  const disconnectedEnvironmentIds = new Set(
+    environmentConnections
+      .filter((environment) =>
+        isSidebarEnvironmentDisconnected(
+          environment.connectionState,
+          liveShellEnvironmentIds.has(environment.environmentId),
+        ),
+      )
+      .map((environment) => environment.environmentId),
+  );
   const inboxReturnsVersion = useSyncExternalStore(
     inboxReturns.subscribe,
     inboxReturns.getSnapshot,
@@ -476,6 +493,7 @@ function useSidebarThreads(input: {
     optimisticDrop,
     workingShelfEnabled,
     sortActiveBySend: folderGroups !== null,
+    disconnectedEnvironmentIds,
     clockKey: `${nowMinute}:${snoozeWakeClock}:${inboxReturnsVersion}`,
   });
 
@@ -611,6 +629,7 @@ function partitionSidebarThreads(input: SidebarThreadPartitionInput) {
     optimisticDrop,
     workingShelfEnabled,
     sortActiveBySend,
+    disconnectedEnvironmentIds,
   } = input;
   const preciseNow = new Date().toISOString();
   const visible = filterSidebarV2VisibleThreads(threads, scopedProjectKeys, delegatedUnderParent);
@@ -619,8 +638,11 @@ function partitionSidebarThreads(input: SidebarThreadPartitionInput) {
   const active: EnvironmentThreadShell[] = [];
   const working: EnvironmentThreadShell[] = [];
   const inbox = (thread: EnvironmentThreadShell, manuallyMoved = false) =>
-    workingShelfEnabled &&
-    (manuallyMoved ? isThreadWorking(thread) : inboxObservation.isWorking(thread))
+    belongsInSidebarWorkingShelf(thread, {
+      enabled: workingShelfEnabled,
+      disconnectedEnvironmentIds,
+      isWorking: manuallyMoved ? isThreadWorking : inboxObservation.isWorking,
+    })
       ? working
       : active;
   const snoozed: EnvironmentThreadShell[] = [];
diff --git a/apps/web/src/state/environments.ts b/apps/web/src/state/environments.ts
index 0b2cab287d223..a35af5e094a00 100644
--- a/apps/web/src/state/environments.ts
+++ b/apps/web/src/state/environments.ts
@@ -114,3 +114,7 @@ export function useEnvironmentMachines() {
 export function useConnectedEnvironmentIds() {
   return useAtomValue(environmentSummaries.connectedEnvironmentIdsAtom);
 }
+
+export function useEnvironmentConnectionSummaries() {
+  return useAtomValue(environmentSummaries.environmentsAtom);
+}