fix: keep current worker visible in collapsed sidebar

web/workspace/src/lib/workspace/sidebar/WorkersNavSection.svelte

@@ -11,7 +11,12 @@
     workspaceWorkersStore,
     type SidebarWorker,
   } from './worker-subscription';
-  import { canShowWorkerInSidebar, sidebarWorkerActivity } from './workers';
+  import {
+    canShowWorkerInSidebar,
+    sidebarWorkerActivity,
+    visibleWorkersForSidebar,
+    workerOwnsSidebarPath,
+  } from './workers';
   import { sidebarWorkdirMeta } from './worker-workdir-meta';
 
   const COLLAPSED_WORKER_COUNT = 6;
@@ -32,7 +37,12 @@
   let menuTrigger = $state<HTMLButtonElement | null>(null);
   let busyAction = $state<{ workerKey: string; kind: WorkerActionKind } | null>(null);
   let visibleWorkers = $derived(
-    expanded ? workers : workers.slice(0, COLLAPSED_WORKER_COUNT),
+    visibleWorkersForSidebar(workers, {
+      workspaceId,
+      currentPath,
+      expanded,
+      limit: COLLAPSED_WORKER_COUNT,
+    }),
   );
   let hiddenWorkerCount = $derived(
     Math.max(0, workers.length - COLLAPSED_WORKER_COUNT),
@@ -173,13 +183,14 @@
         {@const activity = sidebarWorkerActivity(worker)}
         {@const key = workerKey(worker)}
         {@const label = worker.display_name || worker.label}
+        {@const active = workerOwnsSidebarPath(workspaceId, worker, currentPath)}
         {@const workdir = sidebarWorkdirMeta(worker.workdir_attachments)}
         <li class="worker-nav-item" data-worker-actions={key}>
           <a
             href={href}
             class="worker-nav-link"
-            class:active={currentPath === href}
-            aria-current={currentPath === href ? 'page' : undefined}
+            class:active
+            aria-current={active ? 'page' : undefined}
           >
             <span class="worker-status-indicator">
               {#if activity === 'worker-running'}

web/workspace/src/lib/workspace/sidebar/workers.test.ts

@@ -3,6 +3,8 @@ import {
   canShowWorkerInSidebar,
   compareWorkersForSidebar,
   sidebarWorkerActivity,
+  visibleWorkersForSidebar,
+  workerOwnsSidebarPath,
 } from "./workers.ts";
 import type { Worker } from "./types.ts";
 
@@ -79,6 +81,39 @@ Deno.test("sidebar workers sort running then idle then stopped", () => {
   assertEquals(workers.map((candidate) => candidate.worker_id).join(","), "2,1,4,3");
 });
 
+Deno.test("collapsed sidebar keeps the current Worker visible", () => {
+  const workers = Array.from({ length: 8 }, (_, index) =>
+    worker({
+      worker_id: String(index + 1),
+      resource_key: `W-${index + 1}`,
+      display_name: `Worker ${index + 1}`,
+    }));
+  const currentPath = "/w/workspace-1/workers/W-8-worker-8/console";
+
+  assertEquals(
+    workerOwnsSidebarPath("workspace-1", workers[7], currentPath),
+    true,
+  );
+  assertEquals(
+    visibleWorkersForSidebar(workers, {
+      workspaceId: "workspace-1",
+      currentPath,
+      expanded: false,
+      limit: 6,
+    }).map((candidate) => candidate.resource_key).join(","),
+    "W-1,W-2,W-3,W-4,W-5,W-8",
+  );
+  assertEquals(
+    visibleWorkersForSidebar(workers, {
+      workspaceId: "workspace-1",
+      currentPath,
+      expanded: true,
+      limit: 6,
+    }).length,
+    8,
+  );
+});
+
 Deno.test("fatal child stop clears the sidebar SubWorker spinner activity", () => {
   const parent = { state: "idle", has_running_internal_workers: true };
   assertEquals(sidebarWorkerActivity(parent), "subworker-running");

web/workspace/src/lib/workspace/sidebar/workers.ts

@@ -1,3 +1,5 @@
+import { workerHref } from '../resource-links';
+import { ownsRoutePath } from './route-ownership';
 import type { Worker } from './types';
 
 export type SidebarWorkerActivity =
@@ -31,6 +33,38 @@ export function canOpenWorkerConsole(
   return canShowWorkerInSidebar(worker);
 }
 
+type SidebarWorkerLink = Pick<Worker, 'resource_key' | 'display_name'>;
+
+export function workerOwnsSidebarPath(
+  workspaceId: string,
+  worker: SidebarWorkerLink,
+  currentPath: string,
+): boolean {
+  return ownsRoutePath(workerHref(workspaceId, worker), currentPath);
+}
+
+export function visibleWorkersForSidebar<T extends SidebarWorkerLink>(
+  workers: readonly T[],
+  options: {
+    workspaceId: string;
+    currentPath: string;
+    expanded: boolean;
+    limit: number;
+  },
+): readonly T[] {
+  if (options.expanded || workers.length <= options.limit) return workers;
+  if (options.limit <= 0) return [];
+
+  const visible = workers.slice(0, options.limit);
+  const currentIndex = workers.findIndex((worker) =>
+    workerOwnsSidebarPath(options.workspaceId, worker, options.currentPath)
+  );
+  if (currentIndex < options.limit) return visible;
+
+  visible[visible.length - 1] = workers[currentIndex];
+  return visible;
+}
+
 type SortableWorker = Pick<
   Worker,
   'state' | 'display_name' | 'runtime_id' | 'worker_id'