Refactor paginated pages onto shared base, add property coverage

Extract PaginatedPage base for the recent feed and recent profiles page
controllers to remove the duplicated load/canLoadMore pattern introduced
with the 50-item page size. Refresh mutation manifests via the tool. Add
property tests for the base pagination invariants (canLoadMore mirrors
hasMore, load forwards limit/offset, item lookup).

By refactorer.

psf-memo-client/src/services/paginated-page.js

@@ -0,0 +1,41 @@
+/*
+  Shared base for simple paginated page controllers.
+
+  A paginated page loads a single list from a MemoDb method, stores the list
+  and its pagination, and reports whether more items can be loaded. Subclasses
+  supply the memoDb method name, the result list field, and the error message
+  for the missing-client guard, then add their own item finder.
+*/
+
+class PaginatedPage {
+  constructor (deps = {}, { listField, loadMethod, errorMessage }) {
+    this.memoDb = deps.memoDb || null
+    this[listField] = []
+    this.pagination = null
+    this._listField = listField
+    this._loadMethod = loadMethod
+    this._errorMessage = errorMessage
+  }
+
+  async load ({ limit = 50, offset = 0 } = {}) {
+    if (!this.memoDb) {
+      throw new Error(this._errorMessage)
+    }
+
+    const data = await this.memoDb[this._loadMethod]({ limit, offset })
+    this[this._listField] = data[this._listField] || []
+    this.pagination = data.pagination || null
+
+    return { [this._listField]: this[this._listField], pagination: this.pagination }
+  }
+
+  canLoadMore () {
+    return this.pagination?.hasMore ?? false
+  }
+}
+
+module.exports = PaginatedPage
+
+// mutate4javascript-manifest-begin
+// {"version":1,"tested_at":"2026-09-04T17:03:38.880Z","module_hash":"6ba99f826fd1a2bd4a090bedaabe3a8497d4ebe3694138b26090fa5c2f1f6efb","functions":[{"id":"func/PaginatedPage.constructor","name":"PaginatedPage.constructor","line":11,"end_line":18,"hash":"14d764e7220271146f33020326072e2ebb653e1a1372360348e552056d21e0c8"},{"id":"func/PaginatedPage.load","name":"PaginatedPage.load","line":20,"end_line":30,"hash":"b9c43d761b25e202dfbc16beee7ab90b06ee75dcb9ba0799ee014d513b2e9a5c"},{"id":"func/PaginatedPage.canLoadMore","name":"PaginatedPage.canLoadMore","line":32,"end_line":34,"hash":"634983bcc6bbe560daad8326db0dd4bf31d5cb9e45c40112565351dceaf8e5d5"}]}
+// mutate4javascript-manifest-end

psf-memo-client/src/services/recent-feed-page.js

@@ -10,34 +10,22 @@
   boundary.
 */
 
+const PaginatedPage = require('./paginated-page')
+
 const RECENT_FEED_PATH = '/posts/recent'
 
-class RecentFeedPage {
+class RecentFeedPage extends PaginatedPage {
   constructor (deps = {}) {
-    this.memoDb = deps.memoDb || null
-    this.posts = []
-    this.pagination = null
-  }
-
-  async load ({ limit = 50, offset = 0 } = {}) {
-    if (!this.memoDb) {
-      throw new Error('Recent feed page requires a memo db client.')
-    }
-
-    const data = await this.memoDb.getRecentPosts({ limit, offset })
-    this.posts = data.posts || []
-    this.pagination = data.pagination || null
-
-    return { posts: this.posts, pagination: this.pagination }
+    super(deps, {
+      listField: 'posts',
+      loadMethod: 'getRecentPosts',
+      errorMessage: 'Recent feed page requires a memo db client.'
+    })
   }
 
   getPost (txid) {
     return this.posts.find((post) => post.txid === txid) || null
   }
-
-  canLoadMore () {
-    return this.pagination?.hasMore ?? false
-  }
 }
 
 RecentFeedPage.RECENT_FEED_PATH = RECENT_FEED_PATH
@@ -45,5 +33,5 @@ RecentFeedPage.RECENT_FEED_PATH = RECENT_FEED_PATH
 module.exports = RecentFeedPage
 
 // mutate4javascript-manifest-begin
-// {"version":1,"tested_at":"2026-08-27T03:38:52.144Z","module_hash":"e2ee3beff9079c7f93d29043b1428c271fbd1a2b64f2635fbc2cc06fb52a3aab","functions":[{"id":"func/RecentFeedPage.constructor","name":"RecentFeedPage.constructor","line":16,"end_line":20,"hash":"0eb6faf1dfd73ad95b210473ab82fdae513ff1570e401820645661881a2f8d4b"},{"id":"func/RecentFeedPage.load","name":"RecentFeedPage.load","line":22,"end_line":32,"hash":"96e8f2c77aadf98e3a9e71e1f0f6ce98a3e47dd828ffb4626916f56ca32ed137"},{"id":"func/RecentFeedPage.getPost","name":"RecentFeedPage.getPost","line":34,"end_line":36,"hash":"1a6ae1a02b0f79b5b62a2b2324a5f1edbd743bec004fe73cfef7970bead56885"}]}
+// {"version":1,"tested_at":"2026-09-04T17:03:39.630Z","module_hash":"9c0c48d7b21d24fcf640bf461b9798b2377097687c433be64776495ab7166601","functions":[{"id":"func/RecentFeedPage.constructor","name":"RecentFeedPage.constructor","line":18,"end_line":24,"hash":"78adbb7be7ccdc136fb6bb9201a8447b0a484f525a7426f25f281b0ecd78c0ae"},{"id":"func/RecentFeedPage.getPost","name":"RecentFeedPage.getPost","line":26,"end_line":28,"hash":"1a6ae1a02b0f79b5b62a2b2324a5f1edbd743bec004fe73cfef7970bead56885"}]}
 // mutate4javascript-manifest-end

psf-memo-client/src/services/recent-profiles-page.js

@@ -6,29 +6,17 @@
   view can render them.
 */
 
+const PaginatedPage = require('./paginated-page')
+
 const RECENT_PROFILES_PATH = '/profile/recent'
 
-class RecentProfilesPage {
+class RecentProfilesPage extends PaginatedPage {
   constructor (deps = {}) {
-    this.memoDb = deps.memoDb || null
-    this.profiles = []
-    this.pagination = null
-  }
-
-  async load ({ limit = 50, offset = 0 } = {}) {
-    if (!this.memoDb) {
-      throw new Error('Recent profiles page requires a memo db client.')
-    }
-
-    const data = await this.memoDb.getRecentProfiles({ limit, offset })
-    this.profiles = data.profiles || []
-    this.pagination = data.pagination || null
-
-    return { profiles: this.profiles, pagination: this.pagination }
-  }
-
-  canLoadMore () {
-    return this.pagination?.hasMore ?? false
+    super(deps, {
+      listField: 'profiles',
+      loadMethod: 'getRecentProfiles',
+      errorMessage: 'Recent profiles page requires a memo db client.'
+    })
   }
 
   getProfile (addr) {
@@ -39,3 +27,7 @@ class RecentProfilesPage {
 RecentProfilesPage.RECENT_PROFILES_PATH = RECENT_PROFILES_PATH
 
 module.exports = RecentProfilesPage
+
+// mutate4javascript-manifest-begin
+// {"version":1,"tested_at":"2026-09-04T17:03:40.330Z","module_hash":"8a305e7c3c74e6ef33e57da9a0c1f3d3e0eff6ff2d6da99d1383d93874745b65","functions":[{"id":"func/RecentProfilesPage.constructor","name":"RecentProfilesPage.constructor","line":14,"end_line":20,"hash":"01a7876c30597e8eb8e37003290b8a9c9db2d3f2bc7305104e1b02659cc413c5"},{"id":"func/RecentProfilesPage.getProfile","name":"RecentProfilesPage.getProfile","line":22,"end_line":24,"hash":"c93f06a279f8976938fc8b91ce24e9e742c700ac6ff271328192dba9140ae195"}]}
+// mutate4javascript-manifest-end

psf-memo-client/test/property/paginated-page.property.test.js

@@ -0,0 +1,112 @@
+/*
+  Property tests for the shared PaginatedPage base controller.
+
+  The unit tests probe a few fixed pagination shapes. These properties cover
+  the load/`canLoadMore`/lookup invariants over broad random inputs so they
+  hold everywhere for the recent feed and recent profiles pages:
+
+    - has more: canLoadMore always mirrors pagination.hasMore.
+    - forwarding: the load limit and offset forwarded to the memo-db client
+      match exactly what the caller requested.
+    - lookup: the item finder returns a loaded item by key and null otherwise.
+*/
+
+'use strict'
+
+const test = require('node:test')
+const { seededRandom, forAll, intGen } = require('./harness')
+const PaginatedPage = require('../../src/services/paginated-page')
+
+const rng = seededRandom(20260904)
+
+// A minimal concrete subclass exercising the shared base logic.
+class TestPage extends PaginatedPage {
+  constructor (deps = {}) {
+    super(deps, {
+      listField: 'items',
+      loadMethod: 'getItems',
+      errorMessage: 'Test page requires a memo db client.'
+    })
+  }
+
+  getItem (key) {
+    return this.items.find((item) => item.key === key) || null
+  }
+}
+
+function makeMemoDb (items, pagination) {
+  return {
+    async getItems ({ limit, offset }) {
+      return { items, pagination }
+    }
+  }
+}
+
+function fixtureGen () {
+  return () => {
+    const n = intGen(rng, 0, 8)()
+    const items = []
+    for (let i = 0; i < n; i++) {
+      items.push({ key: 'item-' + i, text: 'value ' + i })
+    }
+    return {
+      items,
+      pagination: { hasMore: rng() < 0.5 },
+      limit: intGen(rng, 1, 100)(),
+      offset: intGen(rng, 0, 200)()
+    }
+  }
+}
+
+test('canLoadMore always mirrors pagination.hasMore', async () => {
+  await forAll(
+    fixtureGen(),
+    async ({ items, pagination, limit, offset }) => {
+      const page = new TestPage({ memoDb: makeMemoDb(items, pagination) })
+      await page.load({ limit, offset })
+
+      return page.canLoadMore() === (pagination.hasMore === true) &&
+        page.pagination.hasMore === pagination.hasMore
+    },
+    { label: 'paginated canLoadMore mirrors hasMore' }
+  )
+})
+
+test('load forwards exactly the requested limit and offset to the memo-db client', async () => {
+  await forAll(
+    fixtureGen(),
+    async ({ items, pagination, limit, offset }) => {
+      const calls = []
+      const memoDb = {
+        async getItems (params) {
+          calls.push(params)
+          return { items, pagination }
+        }
+      }
+      const page = new TestPage({ memoDb })
+      await page.load({ limit, offset })
+
+      return calls.length === 1 &&
+        calls[0].limit === limit &&
+        calls[0].offset === offset
+    },
+    { label: 'paginated load forwards limit and offset' }
+  )
+})
+
+test('getItem returns a loaded item by key, otherwise null', async () => {
+  await forAll(
+    fixtureGen(),
+    async ({ items, pagination, limit, offset }) => {
+      const page = new TestPage({ memoDb: makeMemoDb(items, pagination) })
+      await page.load({ limit, offset })
+
+      if (items.length === 0) return true
+
+      const any = page.getItem(items[0].key)
+      if (!any || any.text !== items[0].text) return false
+      return page.getItem('does-not-exist') === null
+    },
+    { label: 'paginated getItem lookup' }
+  )
+})