feat(sidebar): finer recency buckets and hide lone headers

apps/mobile/src/features/home/HomeScreen.tsx

@@ -716,6 +716,8 @@ export function HomeScreen(props: HomeScreenProps) {
             )?.driver ?? null
         }
         environmentLabel={
+          // Multi-server: always label the host. Matches classic list + web
+          // recency rows so cross-project cards stay attributable.
           Object.keys(props.savedConnectionsById).length > 1
             ? (props.savedConnectionsById[item.thread.environmentId]?.environmentLabel ?? null)
             : null
@@ -809,7 +811,12 @@ export function HomeScreen(props: HomeScreenProps) {
               thread={thread}
               projectTitle={item.projectTitle}
               environmentLabel={
-                props.savedConnectionsById[thread.environmentId]?.environmentLabel ?? null
+                // Prefer showing server when multi-env OR recency/flat grouping
+                // so threads from different hosts aren't ambiguous.
+                Object.keys(props.savedConnectionsById).length > 1 ||
+                usesFlatThreadGrouping(props.threadGrouping)
+                  ? (props.savedConnectionsById[thread.environmentId]?.environmentLabel ?? null)
+                  : null
               }
               projectCwd={
                 projectCwdByKey.get(scopedProjectKey(thread.environmentId, thread.projectId)) ??
@@ -838,6 +845,12 @@ export function HomeScreen(props: HomeScreenProps) {
               onGroupAction={updateGroupDisplay}
             />
           );
+        default: {
+          // Exhaustiveness guard: unknown item types must not throw on open.
+          const _exhaustive: never = item;
+          void _exhaustive;
+          return null;
+        }
       }
     },
     [
@@ -853,6 +866,7 @@ export function HomeScreen(props: HomeScreenProps) {
       props.onSelectPendingTask,
       props.onSelectThread,
       props.savedConnectionsById,
+      props.threadGrouping,
       settledThreadKeys,
       settlementEnvironmentIds,
       updateGroupDisplay,
@@ -1135,6 +1149,10 @@ export function HomeScreen(props: HomeScreenProps) {
           data={listLayout.items}
           renderItem={renderItem}
           keyExtractor={keyExtractor}
+          // Mixed item types (headers, section-headers, threads, show-more)
+          // must not share recycle pools — missing this crashes / blanks rows
+          // once shells load (sidebar already passes getItemType).
+          getItemType={(item) => item.type}
           itemsAreEqual={homeListItemsAreEqual}
           drawDistance={500}
           estimatedItemSize={ESTIMATED_THREAD_ROW_HEIGHT}

apps/mobile/src/features/home/homeListItems.test.ts

@@ -254,15 +254,16 @@ describe("buildHomeListLayout", () => {
     expect(layout.stickyHeaderIndices).toEqual([]);
   });
 
-  it("builds recency sections with Today / Older headers", () => {
-    const now = new Date(2026, 2, 15, 12, 0, 0);
-    const startToday = new Date(2026, 2, 15).getTime();
-    const todayIso = new Date(startToday + 3_600_000).toISOString();
-    const olderIso = new Date(startToday - 40 * 24 * 60 * 60 * 1000).toISOString();
-    const todayThread = {
-      ...makeThread("t-today", ProjectId.make("alpha")),
-      updatedAt: todayIso,
-      latestUserMessageAt: todayIso,
+  it("builds recency sections with Last Hour / Older headers when multiple buckets", () => {
+    const now = new Date(2026, 2, 15, 14, 30, 0);
+    const lastHourIso = new Date(now.getTime() - 5 * 60_000).toISOString();
+    const olderIso = new Date(
+      new Date(2026, 2, 15).getTime() - 40 * 24 * 60 * 60 * 1000,
+    ).toISOString();
+    const lastHourThread = {
+      ...makeThread("t-hour", ProjectId.make("alpha")),
+      updatedAt: lastHourIso,
+      latestUserMessageAt: lastHourIso,
     };
     const olderThread = {
       ...makeThread("t-older", ProjectId.make("beta")),
@@ -272,7 +273,7 @@ describe("buildHomeListLayout", () => {
     const layout = buildHomeRecentListLayout({
       pendingTasks: [],
       entries: [
-        { thread: todayThread, projectTitle: "Alpha" },
+        { thread: lastHourThread, projectTitle: "Alpha" },
         { thread: olderThread, projectTitle: "Beta" },
       ],
       groupByRecency: true,
@@ -284,8 +285,38 @@ describe("buildHomeListLayout", () => {
       "section-header",
       "thread",
     ]);
-    expect(layout.items[0]).toMatchObject({ type: "section-header", title: "Today" });
+    expect(layout.items[0]).toMatchObject({ type: "section-header", title: "Last Hour" });
     expect(layout.items[2]).toMatchObject({ type: "section-header", title: "Older" });
     expect(layout.stickyHeaderIndices).toEqual([0, 2]);
   });
+
+  it("omits recency section headers when all threads share one bucket", () => {
+    const now = new Date(2026, 2, 15, 14, 30, 0);
+    const lastHourIso = new Date(now.getTime() - 5 * 60_000).toISOString();
+    const layout = buildHomeRecentListLayout({
+      pendingTasks: [],
+      entries: [
+        {
+          thread: {
+            ...makeThread("t1", ProjectId.make("alpha")),
+            updatedAt: lastHourIso,
+            latestUserMessageAt: lastHourIso,
+          },
+          projectTitle: "Alpha",
+        },
+        {
+          thread: {
+            ...makeThread("t2", ProjectId.make("beta")),
+            updatedAt: lastHourIso,
+            latestUserMessageAt: lastHourIso,
+          },
+          projectTitle: "Beta",
+        },
+      ],
+      groupByRecency: true,
+      now,
+    });
+    expect(itemTypes(layout.items)).toEqual(["thread", "thread"]);
+    expect(layout.stickyHeaderIndices).toEqual([]);
+  });
 });

apps/mobile/src/features/home/homeListItems.ts

@@ -1,5 +1,8 @@
 import type { EnvironmentThreadShell } from "@t3tools/client-runtime/state/shell";
-import { groupSortedThreadsByRecency } from "@t3tools/client-runtime/state/thread-recency-groups";
+import {
+  groupSortedThreadsByRecency,
+  shouldShowRecencySectionHeaders,
+} from "@t3tools/client-runtime/state/thread-recency-groups";
 
 import type { PendingNewTask } from "../../state/use-pending-new-tasks";
 import type { HomeThreadGroup } from "./homeThreadList";
@@ -230,7 +233,9 @@ export function buildHomeListLayout(input: {
  * Each thread row can carry a project title for multi-project context.
  * Callers apply hide-settled / project filters before building entries.
  *
- * When `groupByRecency` is true, inserts Today / Yesterday / … section headers.
+ * When `groupByRecency` is true and more than one non-empty bucket has threads,
+ * inserts Last Hour / Earlier Today / Yesterday / … section headers. A single
+ * bucket renders flat (headers would only repeat the obvious).
  */
 export function buildHomeRecentListLayout(input: {
   readonly pendingTasks: ReadonlyArray<PendingNewTask>;
@@ -244,6 +249,20 @@ export function buildHomeRecentListLayout(input: {
   const items: HomeListItem[] = [];
   const stickyHeaderIndices: number[] = [];
 
+  const appendFlatThreads = () => {
+    const total = input.pendingTasks.length + input.entries.length;
+    for (const [index, entry] of input.entries.entries()) {
+      const absoluteIndex = input.pendingTasks.length + index;
+      items.push({
+        type: "thread",
+        key: `thread:${entry.thread.environmentId}:${entry.thread.id}`,
+        thread: entry.thread,
+        projectTitle: entry.projectTitle,
+        isLast: absoluteIndex === total - 1,
+      });
+    }
+  };
+
   for (const [index, pendingTask] of input.pendingTasks.entries()) {
     items.push({
       type: "pending-task",
@@ -257,17 +276,7 @@ export function buildHomeRecentListLayout(input: {
   }
 
   if (input.groupByRecency !== true) {
-    const total = input.pendingTasks.length + input.entries.length;
-    for (const [index, entry] of input.entries.entries()) {
-      const absoluteIndex = input.pendingTasks.length + index;
-      items.push({
-        type: "thread",
-        key: `thread:${entry.thread.environmentId}:${entry.thread.id}`,
-        thread: entry.thread,
-        projectTitle: entry.projectTitle,
-        isLast: absoluteIndex === total - 1,
-      });
-    }
+    appendFlatThreads();
     return { items, stickyHeaderIndices: [] };
   }
 
@@ -282,6 +291,23 @@ export function buildHomeRecentListLayout(input: {
     input.now,
   );
 
+  // One non-empty bucket (or none): no section headers.
+  if (!shouldShowRecencySectionHeaders(recencyGroups)) {
+    // Pending isLast was computed assuming multi-bucket; fix for flat path.
+    if (input.pendingTasks.length > 0) {
+      const lastPendingIndex = input.pendingTasks.length - 1;
+      const lastPending = items[lastPendingIndex];
+      if (lastPending?.type === "pending-task") {
+        items[lastPendingIndex] = {
+          ...lastPending,
+          isLast: input.entries.length === 0,
+        };
+      }
+    }
+    appendFlatThreads();
+    return { items, stickyHeaderIndices: [] };
+  }
+
   for (const [groupIndex, group] of recencyGroups.entries()) {
     stickyHeaderIndices.push(items.length);
     items.push({

apps/mobile/src/features/threads/ThreadNavigationSidebar.tsx

@@ -1086,7 +1086,9 @@ function ThreadNavigationSidebarPane(
               thread={thread}
               projectTitle={item.projectTitle}
               environmentLabel={
-                savedConnectionsById[thread.environmentId]?.environmentLabel ?? null
+                Object.keys(savedConnectionsById).length > 1 || showFlatThreadList
+                  ? (savedConnectionsById[thread.environmentId]?.environmentLabel ?? null)
+                  : null
               }
               projectCwd={
                 projectCwdByKey.get(scopedProjectKey(thread.environmentId, thread.projectId)) ??
@@ -1120,6 +1122,8 @@ function ThreadNavigationSidebarPane(
               onGroupAction={updateGroupDisplay}
             />
           );
+        default:
+          return null;
       }
     },
     [
@@ -1135,6 +1139,7 @@ function ThreadNavigationSidebarPane(
       projectCwdByKey,
       projectTitleByProjectKey,
       props.onNewThreadInProject,
+      showFlatThreadList,
       props.selectedThreadKey,
       props.width,
       savedConnectionsById,