diff --git a/mobile/app/h/[hostId]/index.tsx b/mobile/app/h/[hostId]/index.tsx
index d88fb6699aa..01ba9c7a963 100644
--- a/mobile/app/h/[hostId]/index.tsx
+++ b/mobile/app/h/[hostId]/index.tsx
@@ -94,6 +94,7 @@ import {
 import { useWorkspaceSections } from '../../../src/worktree/use-workspace-sections'
 import { getMobileWorkspaceLineageGroupKey } from '../../../src/worktree/mobile-workspace-lineage'
 import { areWorktreeListsEqual } from '../../../src/worktree/worktree-list-snapshot'
+import { WorktreeCatalogSnapshotClient } from '../../../src/worktree/worktree-catalog-snapshot-client'
 import { repoColor } from '../../../src/worktree/repo-color'
 import {
   WORKSPACE_GROUP_OPTIONS as GROUP_OPTIONS,
@@ -141,6 +142,7 @@ export function HostScreen({
   const lastConnectedAt = useLastConnectedAt(hostId)
   const clientRef = useRef<RpcClient | null>(null)
   const fetchWorktreesInFlightRef = useRef(false)
+  const worktreeCatalog = useMemo(() => new WorktreeCatalogSnapshotClient(), [])
   const fetchRepoMetadataInFlightRef = useRef(new WeakSet<RpcClient>())
   const fetchRepoMetadataPendingRef = useRef(new WeakSet<RpcClient>())
   const repoMetadataFetchedAtRef = useRef(0)
@@ -423,27 +425,28 @@ export function HostScreen({
       const requestHostId = hostId
 
       try {
-        // Why: worktree.ps silently truncates at 200; use a high cap so large hosts don't drop workspaces.
-        const response = await requestClient.sendRequest('worktree.ps', { limit: 10000 })
+        const pendingCatalog = await worktreeCatalog.fetch(requestClient, requestHostId)
         if (clientRef.current !== requestClient || hostId !== requestHostId) {
           return
         }
         if (!options.allowDuringModal && newWorktreeModalVisibleRef.current) {
           return
         }
-        if (response.ok) {
-          const result = (response as RpcSuccess).result as { worktrees: Worktree[] }
-          // Why: reuse the existing array on identical snapshots to keep SectionList/sort rebuilds off the tap path.
-          setWorktrees((current) =>
-            areWorktreeListsEqual(current, result.worktrees) ? current : result.worktrees
-          )
-          setLastKnownWorktrees((current) =>
-            areWorktreeListsEqual(current, result.worktrees) ? current : result.worktrees
-          )
-          setWorktreesLoaded(true)
-          // Why (#8498): overwrite the home-written cache with the confirmed snapshot so a reconnect/remount can't serve a stale list.
-          if (hostId) {
-            setCachedWorktrees(hostId, result.worktrees)
+        const result = worktreeCatalog.admit(pendingCatalog)
+        if (result) {
+          if (result.changed) {
+            // Why: reuse the existing array on identical snapshots to keep SectionList/sort rebuilds off the tap path.
+            setWorktrees((current) =>
+              areWorktreeListsEqual(current, result.worktrees) ? current : result.worktrees
+            )
+            setLastKnownWorktrees((current) =>
+              areWorktreeListsEqual(current, result.worktrees) ? current : result.worktrees
+            )
+            setWorktreesLoaded(true)
+            // Why (#8498): overwrite the home-written cache with the confirmed snapshot so a reconnect/remount can't serve a stale list.
+            if (hostId) {
+              setCachedWorktrees(hostId, result.worktrees)
+            }
           }
           // Drop the optimistic active override once the host reports it active, so later desktop changes win.
           setOptimisticActiveWorktreeId((pending) =>
@@ -487,7 +490,7 @@ export function HostScreen({
         fetchWorktreesInFlightRef.current = false
       }
     },
-    [client, connState, hostId]
+    [client, connState, hostId, worktreeCatalog]
   )
 
   useFocusEffect(
diff --git a/mobile/src/worktree/worktree-catalog-snapshot-client.test.ts b/mobile/src/worktree/worktree-catalog-snapshot-client.test.ts
new file mode 100644
index 00000000000..4565c605d66
--- /dev/null
+++ b/mobile/src/worktree/worktree-catalog-snapshot-client.test.ts
@@ -0,0 +1,147 @@
+import { describe, expect, it, vi } from 'vitest'
+import type { RpcClient } from '../transport/rpc-client'
+import {
+  admitWorktreeCatalogResponse,
+  WorktreeCatalogSnapshotClient
+} from './worktree-catalog-snapshot-client'
+
+describe('admitWorktreeCatalogResponse', () => {
+  it('accepts new-host full and unchanged responses', () => {
+    const full = admitWorktreeCatalogResponse(
+      { worktrees: [{ id: 'worktree-1' }], snapshotId: 'snapshot-1' },
+      null
+    )
+    const unchanged = admitWorktreeCatalogResponse(
+      { unchanged: true, snapshotId: 'snapshot-1' },
+      'snapshot-1'
+    )
+
+    expect(full).toEqual({
+      kind: 'full',
+      snapshotId: 'snapshot-1',
+      worktrees: [{ id: 'worktree-1' }]
+    })
+    expect(unchanged).toEqual({ kind: 'unchanged', snapshotId: 'snapshot-1' })
+  })
+
+  it('treats an old-host full response as authoritative and clears the token', () => {
+    expect(
+      admitWorktreeCatalogResponse({ worktrees: [{ id: 'worktree-1' }] }, 'stale-token')
+    ).toEqual({
+      kind: 'full',
+      snapshotId: null,
+      worktrees: [{ id: 'worktree-1' }]
+    })
+  })
+
+  it('rejects unchanged responses for a snapshot the client does not own', () => {
+    expect(
+      admitWorktreeCatalogResponse({ unchanged: true, snapshotId: 'snapshot-2' }, 'snapshot-1')
+    ).toEqual({ kind: 'invalid' })
+    expect(admitWorktreeCatalogResponse({ unchanged: true }, 'snapshot-1')).toEqual({
+      kind: 'invalid'
+    })
+  })
+
+  it('rejects malformed success payloads', () => {
+    expect(admitWorktreeCatalogResponse(null, 'snapshot-1')).toEqual({ kind: 'invalid' })
+    expect(
+      admitWorktreeCatalogResponse({ unchanged: false, snapshotId: 'snapshot-1' }, 'snapshot-1')
+    ).toEqual({ kind: 'invalid' })
+    expect(
+      admitWorktreeCatalogResponse({ worktrees: [], snapshotId: 'x'.repeat(129) }, null)
+    ).toEqual({ kind: 'full', snapshotId: null, worktrees: [] })
+  })
+})
+
+function clientWithResults(...results: unknown[]): RpcClient {
+  return {
+    sendRequest: vi.fn(
+      async () =>
+        ({
+          id: 'request',
+          ok: true,
+          result: results.shift(),
+          _meta: { runtimeId: 'runtime' }
+        }) as const
+    )
+  } as unknown as RpcClient
+}
+
+describe('WorktreeCatalogSnapshotClient', () => {
+  it('retains confirmed rows while admitting unchanged responses', async () => {
+    const client = clientWithResults(
+      { worktrees: [{ worktreeId: 'worktree-1' }], snapshotId: 'snapshot-1' },
+      { unchanged: true, snapshotId: 'snapshot-1' }
+    )
+    const snapshots = new WorktreeCatalogSnapshotClient()
+
+    const first = snapshots.admit(await snapshots.fetch(client, 'host-1'))
+    const second = snapshots.admit(await snapshots.fetch(client, 'host-1'))
+
+    expect(first).toMatchObject({ changed: true })
+    expect(second).toEqual({ changed: false, worktrees: first?.worktrees })
+  })
+
+  it('does not advance the token until the caller admits a response', async () => {
+    const client = clientWithResults(
+      { worktrees: [], snapshotId: 'snapshot-1' },
+      { worktrees: [], snapshotId: 'snapshot-1' }
+    )
+    const snapshots = new WorktreeCatalogSnapshotClient()
+
+    await snapshots.fetch(client, 'host-1')
+    snapshots.admit(await snapshots.fetch(client, 'host-1'))
+
+    expect(client.sendRequest).toHaveBeenNthCalledWith(2, 'worktree.ps', {
+      limit: 10_000,
+      afterSnapshotId: null
+    })
+  })
+
+  it('preserves the last admitted token across transport failures', async () => {
+    const client = clientWithResults({ worktrees: [], snapshotId: 'snapshot-1' })
+    const snapshots = new WorktreeCatalogSnapshotClient()
+
+    snapshots.admit(await snapshots.fetch(client, 'host-1'))
+    snapshots.admit(null)
+    await snapshots.fetch(client, 'host-1')
+
+    expect(client.sendRequest).toHaveBeenNthCalledWith(2, 'worktree.ps', {
+      limit: 10_000,
+      afterSnapshotId: 'snapshot-1'
+    })
+  })
+
+  it('clears snapshot ownership after a mismatched unchanged response', async () => {
+    const client = clientWithResults(
+      { worktrees: [], snapshotId: 'snapshot-1' },
+      { unchanged: true, snapshotId: 'snapshot-2' },
+      { worktrees: [], snapshotId: 'snapshot-3' }
+    )
+    const snapshots = new WorktreeCatalogSnapshotClient()
+
+    snapshots.admit(await snapshots.fetch(client, 'host-1'))
+    snapshots.admit(await snapshots.fetch(client, 'host-1'))
+    await snapshots.fetch(client, 'host-1')
+
+    expect(client.sendRequest).toHaveBeenNthCalledWith(3, 'worktree.ps', {
+      limit: 10_000,
+      afterSnapshotId: null
+    })
+  })
+
+  it('resets snapshot ownership when the client or host changes', async () => {
+    const firstClient = clientWithResults({ worktrees: [], snapshotId: 'snapshot-1' })
+    const secondClient = clientWithResults({ worktrees: [], snapshotId: 'snapshot-2' })
+    const snapshots = new WorktreeCatalogSnapshotClient()
+
+    snapshots.admit(await snapshots.fetch(firstClient, 'host-1'))
+    await snapshots.fetch(secondClient, 'host-2')
+
+    expect(secondClient.sendRequest).toHaveBeenCalledWith('worktree.ps', {
+      limit: 10_000,
+      afterSnapshotId: null
+    })
+  })
+})
diff --git a/mobile/src/worktree/worktree-catalog-snapshot-client.ts b/mobile/src/worktree/worktree-catalog-snapshot-client.ts
new file mode 100644
index 00000000000..547205b1944
--- /dev/null
+++ b/mobile/src/worktree/worktree-catalog-snapshot-client.ts
@@ -0,0 +1,108 @@
+import type { RpcClient } from '../transport/rpc-client'
+import type { RpcSuccess } from '../transport/types'
+import type { Worktree } from './workspace-list-sections'
+
+export type WorktreeCatalogAdmission<T> =
+  | { kind: 'full'; snapshotId: string | null; worktrees: T[] }
+  | { kind: 'unchanged'; snapshotId: string }
+  | { kind: 'invalid' }
+
+type PendingWorktreeCatalog = {
+  admission: WorktreeCatalogAdmission<Worktree>
+  client: RpcClient
+  hostId: string
+}
+
+export type AdmittedWorktreeCatalog = {
+  changed: boolean
+  worktrees: Worktree[]
+}
+
+function validSnapshotId(value: unknown): string | null {
+  return typeof value === 'string' && value.length > 0 && value.length <= 128 ? value : null
+}
+
+export function admitWorktreeCatalogResponse<T>(
+  result: unknown,
+  requestedSnapshotId: string | null
+): WorktreeCatalogAdmission<T> {
+  if (!result || typeof result !== 'object') {
+    return { kind: 'invalid' }
+  }
+  const response = result as {
+    snapshotId?: unknown
+    unchanged?: unknown
+    worktrees?: unknown
+  }
+  if ('unchanged' in response) {
+    const snapshotId = validSnapshotId(response.snapshotId)
+    if (response.unchanged === true && snapshotId && snapshotId === requestedSnapshotId) {
+      return { kind: 'unchanged', snapshotId }
+    }
+    return { kind: 'invalid' }
+  }
+
+  if (!Array.isArray(response.worktrees)) {
+    return { kind: 'invalid' }
+  }
+  return {
+    kind: 'full',
+    snapshotId: validSnapshotId(response.snapshotId),
+    worktrees: response.worktrees as T[]
+  }
+}
+
+export class WorktreeCatalogSnapshotClient {
+  private client: RpcClient | null = null
+  private hostId: string | null = null
+  private snapshotId: string | null = null
+  private confirmedWorktrees: Worktree[] | null = null
+
+  async fetch(client: RpcClient, hostId: string): Promise<PendingWorktreeCatalog | null> {
+    if (this.client !== client || this.hostId !== hostId) {
+      this.client = client
+      this.hostId = hostId
+      this.snapshotId = null
+      this.confirmedWorktrees = null
+    }
+    const requestedSnapshotId = this.snapshotId
+    const response = await client.sendRequest('worktree.ps', {
+      limit: 10_000,
+      afterSnapshotId: requestedSnapshotId
+    })
+    if (!response.ok) {
+      return null
+    }
+    return {
+      admission: admitWorktreeCatalogResponse<Worktree>(
+        (response as RpcSuccess).result,
+        requestedSnapshotId
+      ),
+      client,
+      hostId
+    }
+  }
+
+  admit(pending: PendingWorktreeCatalog | null): AdmittedWorktreeCatalog | null {
+    if (!pending) {
+      return null
+    }
+    if (
+      pending.client !== this.client ||
+      pending.hostId !== this.hostId ||
+      pending.admission.kind === 'invalid'
+    ) {
+      this.snapshotId = null
+      return null
+    }
+
+    const admission = pending.admission
+    this.snapshotId = admission.snapshotId
+    if (admission.kind === 'full') {
+      this.confirmedWorktrees = admission.worktrees
+    }
+    return this.confirmedWorktrees
+      ? { changed: admission.kind === 'full', worktrees: this.confirmedWorktrees }
+      : null
+  }
+}
diff --git a/src/main/runtime/rpc/methods/worktree-catalog-snapshot-method.test.ts b/src/main/runtime/rpc/methods/worktree-catalog-snapshot-method.test.ts
new file mode 100644
index 00000000000..c7efa0bbe43
--- /dev/null
+++ b/src/main/runtime/rpc/methods/worktree-catalog-snapshot-method.test.ts
@@ -0,0 +1,60 @@
+import { describe, expect, it, vi } from 'vitest'
+import type { OrcaRuntimeService } from '../../orca-runtime'
+import { RpcDispatcher } from '../dispatcher'
+import { WORKTREE_METHODS } from './worktree'
+
+function makeRuntime() {
+  return {
+    getRuntimeId: () => 'test-runtime',
+    getWorktreePs: vi.fn().mockResolvedValue({
+      worktrees: [],
+      totalCount: 0,
+      truncated: false
+    })
+  } as unknown as OrcaRuntimeService
+}
+
+describe('worktree.ps catalog snapshots', () => {
+  it('preserves the exact legacy response when no snapshot field is sent', async () => {
+    const runtime = makeRuntime()
+    const dispatcher = new RpcDispatcher({ runtime, methods: WORKTREE_METHODS })
+    const response = await dispatcher.dispatch({
+      id: 'legacy',
+      authToken: 'token',
+      method: 'worktree.ps',
+      params: { limit: 10_000 }
+    })
+
+    expect(response).toMatchObject({
+      ok: true,
+      result: { worktrees: [], totalCount: 0, truncated: false }
+    })
+    expect((response as { result: unknown }).result).not.toHaveProperty('snapshotId')
+  })
+
+  it('returns a full snapshot followed by a tiny unchanged response', async () => {
+    const runtime = makeRuntime()
+    const dispatcher = new RpcDispatcher({ runtime, methods: WORKTREE_METHODS })
+    const first = await dispatcher.dispatch({
+      id: 'first',
+      authToken: 'token',
+      method: 'worktree.ps',
+      params: { limit: 10_000, afterSnapshotId: null }
+    })
+    const snapshotId = (first as { result: { snapshotId: string } }).result.snapshotId
+
+    const second = await dispatcher.dispatch({
+      id: 'second',
+      authToken: 'token',
+      method: 'worktree.ps',
+      params: { limit: 10_000, afterSnapshotId: snapshotId }
+    })
+
+    expect(snapshotId).toEqual(expect.any(String))
+    expect(second).toMatchObject({
+      ok: true,
+      result: { unchanged: true, snapshotId }
+    })
+    expect(runtime.getWorktreePs).toHaveBeenCalledTimes(2)
+  })
+})
diff --git a/src/main/runtime/rpc/methods/worktree-schemas.ts b/src/main/runtime/rpc/methods/worktree-schemas.ts
index caf8dd025ff..069a8499d18 100644
--- a/src/main/runtime/rpc/methods/worktree-schemas.ts
+++ b/src/main/runtime/rpc/methods/worktree-schemas.ts
@@ -57,7 +57,8 @@ export const WorktreeTeardownMissingTerminalsParams = WorktreeDetectedListParams
 })
 
 export const WorktreePsParams = z.object({
-  limit: OptionalFiniteNumber
+  limit: OptionalFiniteNumber,
+  afterSnapshotId: z.string().min(1).max(128).nullable().optional()
 })
 
 export const WorktreeSortOrder = z.object({
diff --git a/src/main/runtime/rpc/methods/worktree.ts b/src/main/runtime/rpc/methods/worktree.ts
index 9c6205ed86d..e3e8bd7ffa0 100644
--- a/src/main/runtime/rpc/methods/worktree.ts
+++ b/src/main/runtime/rpc/methods/worktree.ts
@@ -5,6 +5,7 @@ import {
 } from '../../../automations/workspace-provenance'
 import { buildCliWorkspaceProvenance } from '../../../../shared/cli-workspace-provenance'
 import { defineMethod, type RpcMethod } from '../core'
+import { resolveWorktreeCatalogSnapshot } from '../worktree-catalog-snapshot'
 import { resolveRuntimeNavigationTarget } from '../../../../shared/runtime-navigation'
 import {
   WorktreeCreate,
@@ -27,7 +28,13 @@ export const WORKTREE_METHODS: RpcMethod[] = [
   defineMethod({
     name: 'worktree.ps',
     params: WorktreePsParams,
-    handler: async (params, { runtime }) => runtime.getWorktreePs(params.limit)
+    handler: async (params, { runtime }) => {
+      const result = await runtime.getWorktreePs(params.limit)
+      if (params.afterSnapshotId === undefined) {
+        return result
+      }
+      return resolveWorktreeCatalogSnapshot(runtime, params.limit, result, params.afterSnapshotId)
+    }
   }),
   defineMethod({
     name: 'worktree.list',
diff --git a/src/main/runtime/rpc/worktree-catalog-snapshot.test.ts b/src/main/runtime/rpc/worktree-catalog-snapshot.test.ts
new file mode 100644
index 00000000000..f50f5c1db2e
--- /dev/null
+++ b/src/main/runtime/rpc/worktree-catalog-snapshot.test.ts
@@ -0,0 +1,54 @@
+import { describe, expect, it } from 'vitest'
+import type { RuntimeWorktreePsResult } from '../../../shared/runtime-types'
+import { WorktreeCatalogSnapshotCache } from './worktree-catalog-snapshot'
+
+function result(totalCount: number): RuntimeWorktreePsResult {
+  return { worktrees: [], totalCount, truncated: false }
+}
+
+describe('WorktreeCatalogSnapshotCache', () => {
+  it('returns unchanged only when the caller owns the exact completed snapshot', () => {
+    const snapshots = new WorktreeCatalogSnapshotCache()
+    const first = snapshots.resolve(10_000, result(1), null)
+    expect(first).toMatchObject({ totalCount: 1 })
+    expect('snapshotId' in first).toBe(true)
+
+    const snapshotId = first.snapshotId
+    expect(snapshots.resolve(10_000, result(1), snapshotId)).toEqual({
+      unchanged: true,
+      snapshotId
+    })
+    expect(snapshots.resolve(10_000, result(1), 'unknown')).toEqual({
+      ...result(1),
+      snapshotId
+    })
+  })
+
+  it('issues a new snapshot for changed content or a different limit', () => {
+    const snapshots = new WorktreeCatalogSnapshotCache()
+    const first = snapshots.resolve(10_000, result(1), null)
+    const changed = snapshots.resolve(10_000, result(2), first.snapshotId)
+    const differentLimit = snapshots.resolve(200, result(2), changed.snapshotId)
+
+    expect(changed.snapshotId).not.toBe(first.snapshotId)
+    expect(differentLimit.snapshotId).not.toBe(changed.snapshotId)
+  })
+
+  it('repairs completion-order cache replacement with a full response', () => {
+    const snapshots = new WorktreeCatalogSnapshotCache()
+    const older = snapshots.resolve(10_000, result(1), null)
+    const newer = snapshots.resolve(10_000, result(2), older.snapshotId)
+    snapshots.resolve(10_000, result(1), older.snapshotId)
+
+    const repaired = snapshots.resolve(10_000, result(2), newer.snapshotId)
+    expect(repaired).toMatchObject({ totalCount: 2 })
+    expect(repaired).not.toHaveProperty('unchanged')
+  })
+
+  it('scopes snapshot ids to one runtime cache', () => {
+    const left = new WorktreeCatalogSnapshotCache().resolve(10_000, result(1), null)
+    const right = new WorktreeCatalogSnapshotCache().resolve(10_000, result(1), null)
+
+    expect(left.snapshotId).not.toBe(right.snapshotId)
+  })
+})
diff --git a/src/main/runtime/rpc/worktree-catalog-snapshot.ts b/src/main/runtime/rpc/worktree-catalog-snapshot.ts
new file mode 100644
index 00000000000..2e72ee2dd88
--- /dev/null
+++ b/src/main/runtime/rpc/worktree-catalog-snapshot.ts
@@ -0,0 +1,52 @@
+import { randomUUID } from 'node:crypto'
+import { isDeepStrictEqual } from 'node:util'
+import type {
+  RuntimeWorktreePsConditionalResult,
+  RuntimeWorktreePsResult
+} from '../../../shared/runtime-types'
+
+type CachedWorktreeCatalog = {
+  limit: number | undefined
+  result: RuntimeWorktreePsResult
+  snapshotId: string
+}
+
+export class WorktreeCatalogSnapshotCache {
+  private readonly runtimeScope = randomUUID()
+  private sequence = 0
+  private cached: CachedWorktreeCatalog | null = null
+
+  resolve(
+    limit: number | undefined,
+    result: RuntimeWorktreePsResult,
+    afterSnapshotId: string | null
+  ): RuntimeWorktreePsConditionalResult {
+    const cached = this.cached
+    if (cached !== null && cached.limit === limit && isDeepStrictEqual(cached.result, result)) {
+      if (afterSnapshotId === cached.snapshotId) {
+        return { unchanged: true, snapshotId: cached.snapshotId }
+      }
+      return { ...result, snapshotId: cached.snapshotId }
+    }
+
+    const snapshotId = `${this.runtimeScope}:${++this.sequence}`
+    this.cached = { limit, result, snapshotId }
+    return { ...result, snapshotId }
+  }
+}
+
+const snapshotsByRuntime = new WeakMap<object, WorktreeCatalogSnapshotCache>()
+
+export function resolveWorktreeCatalogSnapshot(
+  runtime: object,
+  limit: number | undefined,
+  result: RuntimeWorktreePsResult,
+  afterSnapshotId: string | null
+): RuntimeWorktreePsConditionalResult {
+  let snapshots = snapshotsByRuntime.get(runtime)
+  if (!snapshots) {
+    snapshots = new WorktreeCatalogSnapshotCache()
+    snapshotsByRuntime.set(runtime, snapshots)
+  }
+  return snapshots.resolve(limit, result, afterSnapshotId)
+}
diff --git a/src/shared/runtime-types.ts b/src/shared/runtime-types.ts
index 5eca1063ab8..d0f98e68360 100644
--- a/src/shared/runtime-types.ts
+++ b/src/shared/runtime-types.ts
@@ -843,6 +843,19 @@ export type RuntimeWorktreePsResult = {
   truncated: boolean
 }
 
+export type RuntimeWorktreePsSnapshotResult = RuntimeWorktreePsResult & {
+  snapshotId: string
+}
+
+export type RuntimeWorktreePsUnchangedResult = {
+  unchanged: true
+  snapshotId: string
+}
+
+export type RuntimeWorktreePsConditionalResult =
+  | RuntimeWorktreePsSnapshotResult
+  | RuntimeWorktreePsUnchangedResult
+
 export type RuntimeRepoList = {
   repos: Repo[]
 }