diff --git a/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.test.ts b/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.test.ts
index 82ce28019c8..e3036665a35 100644
--- a/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.test.ts
+++ b/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.test.ts
@@ -4,6 +4,7 @@ import type { ExecutionHostId } from '../../../../../../shared/execution-host'
 import {
   HOST_STICKY_PINNED_HEIGHT,
   buildLineageRowRekeyMap,
+  estimateRenderRowSize,
   extractWorktreeVirtualRowIndexes,
   getActiveStickyIndexesForScroll,
   getStickyHeaderIndexes,
@@ -77,6 +78,75 @@ describe('getRenderRowKey', () => {
 })
 
 describe('getActiveStickyIndexesForScroll', () => {
+  it('hands off adjacent collapsed project headers at the slot below the host', () => {
+    const adjacentRows = [hostRow('local'), groupRow('collapsed'), groupRow('incoming')]
+    const items = [virtualItem(0, 0), virtualItem(1, 42), virtualItem(2, 80)]
+    const resolve = (scrollOffset: number) =>
+      getActiveStickyIndexesForScroll({
+        rows: adjacentRows,
+        rangeStartIndex: 1,
+        scrollOffset,
+        stickyHeaderIndexes: getStickyHeaderIndexes(adjacentRows),
+        virtualItems: items
+      })
+
+    expect(resolve(43)).toEqual({ hostIndex: 0, groupIndex: 1 })
+    expect(resolve(44)).toEqual({ hostIndex: 0, groupIndex: 2 })
+    expect(resolve(43)).toEqual({ hostIndex: 0, groupIndex: 1 })
+  })
+
+  it('pins the first project once it reaches the host slot while the range still starts at the host', () => {
+    const firstRows = [hostRow('local'), groupRow('first')]
+    expect(
+      getActiveStickyIndexesForScroll({
+        rows: firstRows,
+        rangeStartIndex: 0,
+        scrollOffset: 6,
+        stickyHeaderIndexes: getStickyHeaderIndexes(firstRows),
+        virtualItems: [virtualItem(0, 0), virtualItem(1, 42)]
+      })
+    ).toEqual({ hostIndex: 0, groupIndex: 1 })
+  })
+
+  it('selects the last header at the slot after crossing several collapsed groups', () => {
+    const adjacentRows = [
+      hostRow('local'),
+      groupRow('first'),
+      groupRow('second'),
+      groupRow('third')
+    ]
+    expect(
+      getActiveStickyIndexesForScroll({
+        rows: adjacentRows,
+        rangeStartIndex: 0,
+        scrollOffset: 82,
+        stickyHeaderIndexes: getStickyHeaderIndexes(adjacentRows),
+        virtualItems: [
+          virtualItem(0, 0),
+          virtualItem(1, 42),
+          virtualItem(2, 80),
+          virtualItem(3, 118)
+        ]
+      })
+    ).toEqual({ hostIndex: 0, groupIndex: 3 })
+  })
+
+  it.each([
+    { scrollOffset: 399, hostIndex: 0, groupIndex: 1 },
+    { scrollOffset: 400, hostIndex: 4, groupIndex: null },
+    { scrollOffset: 464, hostIndex: 4, groupIndex: 5 }
+  ])('resolves host transitions with a lagging range at $scrollOffset', (expected) => {
+    expect(
+      getActiveStickyIndexesForScroll({
+        rows,
+        rangeStartIndex: 3,
+        scrollOffset: expected.scrollOffset,
+        stickyHeaderIndexes,
+        virtualItems
+      })
+    ).toEqual({ hostIndex: expected.hostIndex, groupIndex: expected.groupIndex })
+  })
+
   it('pins the host and its inner group while scrolled inside a section', () => {
     expect(
       getActiveStickyIndexesForScroll({
@@ -195,6 +265,14 @@ describe('getActiveStickyIndexesForScroll', () => {
   })
 })
 
+describe('host header row height', () => {
+  it('reserves the host card height and its padding before the next row', () => {
+    const hostRows = [hostRow('local'), groupRow('first'), hostRow('ssh:remote')]
+    expect(estimateRenderRowSize(hostRows, 0, 0, null)).toBe(36)
+    expect(estimateRenderRowSize(hostRows, 2, 0, null)).toBe(40)
+  })
+})
+
 describe('extractWorktreeVirtualRowIndexes', () => {
   it('keeps the pinned host mounted even when scrolled out of range', () => {
     const indexes = extractWorktreeVirtualRowIndexes({
diff --git a/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.ts b/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.ts
index 8414e583679..ea1e0e708de 100644
--- a/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.ts
+++ b/src/renderer/src/components/sidebar/worktree-list/viewport/virtual-rows.ts
@@ -5,7 +5,8 @@ import { getRenderRowKey } from '../listing/render-row'
 import type { RenderRow } from '../listing/render-row'
 
 export const GROUP_HEADER_ROW_HEIGHT = 28
-export const HOST_HEADER_ROW_HEIGHT = 32
+// Why: HostSectionHeader wraps its h-8 (32px) card in pt-1 (4px), so the row is 36px.
+export const HOST_HEADER_ROW_HEIGHT = 36
 export const WORKTREE_SIDEBAR_VIRTUAL_ROW_GAP = 6
 const SECONDARY_GROUP_HEADER_TOP_MARGIN = 4
 const IMPORTED_WORKTREES_LINE_ROW_HEIGHT = 36
@@ -162,7 +163,7 @@ export function getStickyHeaderIndexes(rows: readonly RenderRow[]): number[] {
 // Why: the pinned host card is h-8 (32px) inside a pt-1 (4px) wrapper; the
 // group tier pins one pixel up to sit flush beneath it. Keep in sync with
 // HostSectionHeader's layout.
-export const HOST_STICKY_PINNED_HEIGHT = 36
+export const HOST_STICKY_PINNED_HEIGHT = HOST_HEADER_ROW_HEIGHT
 
 export type ActiveStickyIndexes = {
   /** Pinned host card (tier 1), or null outside host sections. */
@@ -186,17 +187,25 @@ export function getActiveStickyIndexesForScroll(args: {
   virtualItems: readonly VirtualItem[]
 }): ActiveStickyIndexes {
   const hostIndexes = getHostStickyIndexes(args.rows, args.stickyHeaderIndexes)
+  const virtualItemsByIndex = new Map(args.virtualItems.map((item) => [item.index, item]))
 
   const resolveWithHandoff = (
     candidates: readonly number[],
     pinnedOffset: number,
     fallbackToCandidate: boolean
   ): number | null => {
-    const candidateIndex = getActiveStickyHeaderIndex(candidates, args.rangeStartIndex)
+    // The group slot can reach a header before the viewport's range start does.
+    const candidateIndex =
+      candidates.findLast(
+        (index) =>
+          index <= args.rangeStartIndex ||
+          (virtualItemsByIndex.get(index)?.start ?? Number.POSITIVE_INFINITY) <=
+            args.scrollOffset + pinnedOffset
+      ) ?? null
     if (candidateIndex === null) {
       return null
     }
-    const candidate = args.virtualItems.find((item) => item.index === candidateIndex)
+    const candidate = virtualItemsByIndex.get(candidateIndex)
     if (!candidate) {
       // Why: scrollToIndex/reveal can advance rangeStartIndex before TanStack
       // mounts the candidate row. Pinning without geometry lets a Project
@@ -204,7 +213,7 @@ export function getActiveStickyIndexesForScroll(args: {
       // sticky; group tier waits for geometry, host tier may keep the id.
       const previous = getPreviousStickyHeaderIndex(candidates, candidateIndex)
       if (previous !== null) {
-        const previousItem = args.virtualItems.find((item) => item.index === previous)
+        const previousItem = virtualItemsByIndex.get(previous)
         if (previousItem) {
           return previous
         }