Refactor topic actions: reduce CRAP/DRY, add property coverage, complete acceptance

- Add unit coverage for Profiles topic follow state to bring CRAP to 4.
- DRY Profiles set/get follow state via shared nested-map helpers.
- Add TopicQuery topic-follow read-side property tests and MemoTopicPost
  byte-accounting property tests.
- Complete client and DB acceptance step handlers and mocks for the
  topic-follow and topic-post features.

By refactorer.

psf-memo-client/acceptance/lib/handlers.js

@@ -38,6 +38,9 @@ const ProfilePage = require('../../src/services/profile-page')
 const ThreadPage = require('../../src/services/thread-page')
 const TopicDiscoveryPage = require('../../src/services/topic-discovery-page')
 const TopicFeedPage = require('../../src/services/topic-feed-page')
+const MemoTopicFollow = require('../../src/services/memo-topic-follow')
+const MemoTopicPost = require('../../src/services/memo-topic-post')
+const TopicPostPage = require('../../src/services/topic-post-page')
 
 const MEMO_POST_PREFIX = MemoPost.MEMO_POST_PREFIX
 const MEMO_REPLY_PREFIX = MemoReply.MEMO_REPLY_PREFIX
@@ -47,6 +50,9 @@ const MEMO_SET_AVATAR_URL_PREFIX = MemoSetAvatarUrl.MEMO_SET_AVATAR_URL_PREFIX
 const MEMO_LIKE_PREFIX = MemoLike.MEMO_LIKE_PREFIX
 const MEMO_FOLLOW_PREFIX = MemoFollow.MEMO_FOLLOW_PREFIX
 const MEMO_UNFOLLOW_PREFIX = MemoFollow.MEMO_UNFOLLOW_PREFIX
+const MEMO_TOPIC_MESSAGE_PREFIX = MemoTopicPost.MEMO_TOPIC_MESSAGE_PREFIX
+const MEMO_TOPIC_FOLLOW_PREFIX = MemoTopicFollow.MEMO_TOPIC_FOLLOW_PREFIX
+const MEMO_TOPIC_UNFOLLOW_PREFIX = MemoTopicFollow.MEMO_TOPIC_UNFOLLOW_PREFIX
 
 // Default author address used by Gherkin steps that refer to "the author address".
 const AUTHOR_ADDRESS = 'bitcoincash:qz7v6ztvzu2f2xd2ww8pnx9vwk0g4ncvfvavktg0jc'
@@ -98,11 +104,13 @@ function makeProfiles () {
   const bios = {}
   const avatarUrls = {}
   const following = {}
+  const topicFollowing = {}
   return {
     names,
     bios,
     avatarUrls,
     following,
+    topicFollowing,
     setName: (addr, name) => { names[addr] = name },
     getName: (addr) => names[addr] || null,
     setBio: (addr, bio) => { bios[addr] = bio },
@@ -113,7 +121,12 @@ function makeProfiles () {
       if (!following[selfAddr]) following[selfAddr] = {}
       following[selfAddr][targetAddr] = isFollowing
     },
-    getFollowState: (selfAddr, targetAddr) => following[selfAddr]?.[targetAddr] || false
+    getFollowState: (selfAddr, targetAddr) => following[selfAddr]?.[targetAddr] || false,
+    setTopicFollowState: (selfAddr, room, isFollowing) => {
+      if (!topicFollowing[selfAddr]) topicFollowing[selfAddr] = {}
+      topicFollowing[selfAddr][room] = isFollowing
+    },
+    getTopicFollowState: (selfAddr, room) => topicFollowing[selfAddr]?.[room] || false
   }
 }
 
@@ -136,6 +149,7 @@ function makeMemoDb () {
   const topics = []
   const topicPosts = {}
   const topicCounts = new Map()
+  const topicFollow = new Map()
 
   return {
     posts,
@@ -171,6 +185,20 @@ function makeMemoDb () {
     setFollowState (followerAddr, followeeAddr, following) {
       followState[`${followerAddr}:${followeeAddr}`] = following
     },
+    setTopicFollowState (addr, room, following) {
+      if (!topicFollow.has(room)) topicFollow.set(room, new Map())
+      topicFollow.get(room).set(addr, following)
+    },
+    async getTopicFollowState (room, addr) {
+      return topicFollow.get(room)?.get(addr) || false
+    },
+    async getTopicFollowers (room) {
+      const addrs = []
+      for (const [addr, following] of (topicFollow.get(room) || new Map()).entries()) {
+        if (following) addrs.push(addr)
+      }
+      return addrs
+    },
     async getRecentPosts ({ limit = 100, offset = 0 } = {}) {
       const page = posts.slice(offset, offset + limit)
       return { posts: page, pagination: { total: posts.length, limit, offset, hasMore: offset + page.length < posts.length } }
@@ -212,6 +240,7 @@ function createWorld () {
   const memoReply = new MemoReply({ wallet, thread })
   const memoLike = new MemoLike({ wallet, feed })
   const memoFollow = new MemoFollow({ wallet, profiles })
+  const memoTopicFollow = new MemoTopicFollow({ wallet, profiles })
   const memoDb = makeMemoDb()
 
   const world = {
@@ -222,6 +251,7 @@ function createWorld () {
     memoReply,
     memoLike,
     memoFollow,
+    memoTopicFollow,
     memoDb,
     currentPath: null,
     menuOpen: false,
@@ -326,6 +356,13 @@ function findDisplayedPost (txid, world) {
   return null
 }
 
+// True when the currently displayed page is a topic feed (used to dispatch the
+// shared "Follow/Unfollow button" steps between the profile page and the topic
+// feed page).
+function isTopicFeedActive (world) {
+  return Boolean(world.currentPath && String(world.currentPath).startsWith('/topics/'))
+}
+
 // Handler registry. Each entry: { pattern, run }.
 // run receives (match, exampleStore, world, step).
 const handlers = [
@@ -1340,14 +1377,22 @@ const handlers = [
     name: 'click Follow button',
     pattern: /^I click the Follow button$/,
     async run (m, example, world) {
-      await world.profilePage.follow()
+      if (isTopicFeedActive(world)) {
+        await world.topicFeedPage.follow()
+      } else {
+        await world.profilePage.follow()
+      }
     }
   },
   {
     name: 'click Unfollow button',
     pattern: /^I click the Unfollow button$/,
     async run (m, example, world) {
-      await world.profilePage.unfollow()
+      if (isTopicFeedActive(world)) {
+        await world.topicFeedPage.unfollow()
+      } else {
+        await world.profilePage.unfollow()
+      }
     }
   },
   {
@@ -1471,12 +1516,23 @@ const handlers = [
   },
   {
     name: 'open topic feed',
-    pattern: /^I open the topic feed for "?(<topic>|[^"]+)"?$/,
+    pattern: /^I open the topic feed for (?:the topic )?"?(<topic>|[^"]+)"?$/,
     async run (m, example, world) {
       const room = resolveParam(m[1], example)
-      world.topicFeedPage = new TopicFeedPage({ memoDb: world.memoDb, room })
+      const myAddr = world.wallet.walletInfo.cashAddress
+      world.topicFeedPage = new TopicFeedPage({
+        memoDb: world.memoDb,
+        room,
+        myAddr,
+        memoTopicFollow: world.memoTopicFollow
+      })
       await world.topicFeedPage.load()
       world.currentPath = TopicFeedPage.topicFeedPath(room)
+
+      // Set up the topic post composer for this room so topic messages can be
+      // composed and broadcast, reflecting new posts onto the shared feed.
+      const memoTopicPost = new MemoTopicPost({ wallet: world.wallet, room, feed: world.feed })
+      world.topicPostPage = new TopicPostPage({ memoTopicPost })
     }
   },
   {
@@ -1503,6 +1559,147 @@ const handlers = [
         throw new Error(`Expected topic feed to be empty, but found ${Array.isArray(posts) ? posts.length : 'non-array'} posts.`)
       }
     }
+  },
+  {
+    name: 'API reports I do not follow topic',
+    pattern: /^the psf-memo-db API reports that I do not follow the topic (<topic>)$/,
+    run (m, example, world) {
+      const room = resolveParam(m[1], example)
+      const myAddr = world.wallet.walletInfo.cashAddress
+      world.memoDb.setTopicFollowState(myAddr, room, false)
+    }
+  },
+  {
+    name: 'API reports I follow topic',
+    pattern: /^the psf-memo-db API reports that I follow the topic (<topic>)$/,
+    run (m, example, world) {
+      const room = resolveParam(m[1], example)
+      const myAddr = world.wallet.walletInfo.cashAddress
+      world.memoDb.setTopicFollowState(myAddr, room, true)
+    }
+  },
+  {
+    name: 'topic feed page shows Follow button',
+    pattern: /^the topic feed page shows a Follow button$/,
+    run (m, example, world) {
+      if (!world.topicFeedPage) throw new Error('No topic feed page is loaded.')
+      if (!world.topicFeedPage.canFollow()) throw new Error('Topic feed cannot show a Follow button.')
+      if (world.topicFeedPage.isFollowing()) throw new Error('Topic feed shows Unfollow, but Follow was expected.')
+    }
+  },
+  {
+    name: 'topic feed page shows Unfollow button',
+    pattern: /^the topic feed page shows an Unfollow button$/,
+    run (m, example, world) {
+      if (!world.topicFeedPage) throw new Error('No topic feed page is loaded.')
+      if (!world.topicFeedPage.canFollow()) throw new Error('Topic feed cannot show an Unfollow button.')
+      if (!world.topicFeedPage.isFollowing()) throw new Error('Topic feed shows Follow, but Unfollow was expected.')
+    }
+  },
+  {
+    name: 'broadcasts topic-follow prefix',
+    pattern: /^the app broadcasts an OP_RETURN transaction with the Memo topic-follow prefix for the topic (<topic>)$/,
+    run (m, example, world) {
+      const room = resolveParam(m[1], example)
+      const broadcasts = world.wallet.broadcasts
+      if (!broadcasts.length) throw new Error('No OP_RETURN transaction was broadcast.')
+      const last = broadcasts[broadcasts.length - 1]
+      if (last.prefix !== MEMO_TOPIC_FOLLOW_PREFIX) {
+        throw new Error(`Expected Memo topic-follow prefix ${MEMO_TOPIC_FOLLOW_PREFIX}, got "${last.prefix}".`)
+      }
+      if (last.msg !== room) {
+        throw new Error(`Broadcast topic-follow payload did not match topic ${room}.`)
+      }
+    }
+  },
+  {
+    name: 'broadcasts topic-unfollow prefix',
+    pattern: /^the app broadcasts an OP_RETURN transaction with the Memo topic-unfollow prefix for the topic (<topic>)$/,
+    run (m, example, world) {
+      const room = resolveParam(m[1], example)
+      const broadcasts = world.wallet.broadcasts
+      if (!broadcasts.length) throw new Error('No OP_RETURN transaction was broadcast.')
+      const last = broadcasts[broadcasts.length - 1]
+      if (last.prefix !== MEMO_TOPIC_UNFOLLOW_PREFIX) {
+        throw new Error(`Expected Memo topic-unfollow prefix ${MEMO_TOPIC_UNFOLLOW_PREFIX}, got "${last.prefix}".`)
+      }
+      if (last.msg !== room) {
+        throw new Error(`Broadcast topic-unfollow payload did not match topic ${room}.`)
+      }
+    }
+  },
+  {
+    name: 'compose topic message',
+    pattern: /^I compose a topic message with the text "<([A-Za-z0-9_]+)>"$/,
+    run (m, example, world) {
+      const param = m[1]
+      if (!(param in example)) throw new Error(`Missing example value for "${param}"`)
+      world.topicPostPage.setInput(example[param])
+    }
+  },
+  {
+    name: 'submit topic message',
+    pattern: /^I submit the topic message$/,
+    async run (m, example, world) {
+      await world.topicPostPage.submit()
+    }
+  },
+  {
+    name: 'broadcasts topic-message prefix',
+    pattern: /^the app broadcasts an OP_RETURN transaction with the Memo topic-message prefix for the topic (<topic>)$/,
+    run (m, example, world) {
+      const room = resolveParam(m[1], example)
+      const broadcasts = world.wallet.broadcasts
+      if (!broadcasts.length) throw new Error('No OP_RETURN transaction was broadcast.')
+      const last = broadcasts[broadcasts.length - 1]
+      if (last.prefix !== MEMO_TOPIC_MESSAGE_PREFIX) {
+        throw new Error(`Expected Memo topic-message prefix ${MEMO_TOPIC_MESSAGE_PREFIX}, got "${last.prefix}".`)
+      }
+      const expectedPayload = room + world.topicPostPage.input
+      if (last.msg !== expectedPayload) {
+        throw new Error(`Broadcast topic-message payload did not match ${room} + input.`)
+      }
+    }
+  },
+  {
+    name: 'topic feed shows new post from my address',
+    pattern: /^the topic feed shows a new post from my address with the text "(.+)"$/,
+    run (m, example, world) {
+      const expectedText = resolveParam(m[1], example)
+      const myAddress = world.wallet.walletInfo.cashAddress
+      const found = world.feed.posts.find((p) => p.text === expectedText && p.address === myAddress)
+      if (!found) throw new Error(`Topic feed does not show the new post with text "${expectedText}".`)
+    }
+  },
+  {
+    name: 'topic post composer shows validation error',
+    pattern: /^the topic post composer shows a validation error$/,
+    run (m, example, world) {
+      if (world.topicPostPage.submitError !== 'topic_post_validation') {
+        throw new Error(`Expected topic_post_validation, got ${world.topicPostPage.submitError}.`)
+      }
+    }
+  },
+  {
+    name: 'topic post composer shows length error',
+    pattern: /^the topic post composer shows a length error$/,
+    run (m, example, world) {
+      if (world.topicPostPage.submitError !== 'topic_post_length') {
+        throw new Error(`Expected topic_post_length, got ${world.topicPostPage.submitError}.`)
+      }
+    }
+  },
+  {
+    name: 'topic post composer remaining byte count',
+    pattern: /^the topic post composer shows a remaining byte count of (<count>)$/,
+    run (m, example, world) {
+      const expected = parseInt(resolveParam(m[1], example), 10)
+      if (Number.isNaN(expected)) throw new Error(`Invalid expected count for "${m[1]}".`)
+      const actual = world.topicPostPage.remainingCount()
+      if (actual !== expected) {
+        throw new Error(`Expected ${expected} remaining bytes, got ${actual}.`)
+      }
+    }
   }
 ]
 

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

@@ -50,35 +50,40 @@ class Profiles {
 
   // Track whether the current wallet follows a given address.
   setFollowState (selfAddr, targetAddr, isFollowing) {
-    if (!selfAddr || !targetAddr) return
-    if (!this.following.has(selfAddr)) {
-      this.following.set(selfAddr, new Map())
-    }
-    this.following.get(selfAddr).set(targetAddr, isFollowing)
+    this._setMapState(this.following, selfAddr, targetAddr, isFollowing)
   }
 
   getFollowState (selfAddr, targetAddr) {
-    if (!selfAddr || !targetAddr) return false
-    return this.following.get(selfAddr)?.get(targetAddr) || false
+    return this._getMapState(this.following, selfAddr, targetAddr)
   }
 
   // Track whether the current wallet follows a given topic.
   setTopicFollowState (selfAddr, room, isFollowing) {
-    if (!selfAddr || !room) return
-    if (!this.topicFollowing.has(selfAddr)) {
-      this.topicFollowing.set(selfAddr, new Map())
-    }
-    this.topicFollowing.get(selfAddr).set(room, isFollowing)
+    this._setMapState(this.topicFollowing, selfAddr, room, isFollowing)
   }
 
   getTopicFollowState (selfAddr, room) {
-    if (!selfAddr || !room) return false
-    return this.topicFollowing.get(selfAddr)?.get(room) || false
+    return this._getMapState(this.topicFollowing, selfAddr, room)
+  }
+
+  // Set a boolean value on a per-self-address nested map.
+  _setMapState (map, selfAddr, key, value) {
+    if (!selfAddr || !key) return
+    if (!map.has(selfAddr)) {
+      map.set(selfAddr, new Map())
+    }
+    map.get(selfAddr).set(key, value)
+  }
+
+  // Read a boolean value from a per-self-address nested map.
+  _getMapState (map, selfAddr, key) {
+    if (!selfAddr || !key) return false
+    return map.get(selfAddr)?.get(key) || false
   }
 }
 
 module.exports = Profiles
 
 // mutate4javascript-manifest-begin
-// {"version":1,"tested_at":"2026-08-27T17:52:37.432Z","module_hash":"f729d4125eea29c45c4a0d7bd691a5f590512922f2ba78c85756643638fb0859","functions":[{"id":"func/Profiles.constructor","name":"Profiles.constructor","line":13,"end_line":18,"hash":"574f0b3772f783646c283c6ddc4d5ff200ca1f9918ab1fa668205003f885d4d3"},{"id":"func/Profiles.setName","name":"Profiles.setName","line":20,"end_line":23,"hash":"5a36c6e237798608de0bedd8744b75000c0eec5c0a6a64c870a25bcdf20aed21"},{"id":"func/Profiles.getName","name":"Profiles.getName","line":25,"end_line":28,"hash":"2fcb9d84687ea0f3b24f3e34c0a72eda55a4e869b87e08a7f4551321a4166198"},{"id":"func/Profiles.setBio","name":"Profiles.setBio","line":30,"end_line":33,"hash":"3825665ead1ba9bb217694c45a17bb2e11c78ffa053e5e90111a4b9208183b56"},{"id":"func/Profiles.getBio","name":"Profiles.getBio","line":35,"end_line":38,"hash":"2e9708249db4a0e4fa642cbe52e6216144ec91283281c61dee2ff3cc3d8f1572"},{"id":"func/Profiles.setAvatarUrl","name":"Profiles.setAvatarUrl","line":40,"end_line":43,"hash":"e4ccb0164fee4ab6cc3a1290fb4bf85e4a79f2227ca72872b1f10bc616926fd9"},{"id":"func/Profiles.getAvatarUrl","name":"Profiles.getAvatarUrl","line":45,"end_line":48,"hash":"0aa58dc15fd519e553136d04d1954e18084f79a6cd9349dc89b1136cf0a22a2b"},{"id":"func/Profiles.setFollowState","name":"Profiles.setFollowState","line":51,"end_line":57,"hash":"aa527936b6ca92a502e93e8241803318700c528e05f68ff7fb6fac1d410c197c"},{"id":"func/Profiles.getFollowState","name":"Profiles.getFollowState","line":59,"end_line":62,"hash":"299a44adb289026bf3b89a21947fc23bf05f5a40f07abb7f1bbd311c0479f562"}]}
+// {"version":1,"tested_at":"2026-08-28T18:00:08.907Z","module_hash":"1cec5125fb228d43d47e4ec171eb43c492f2bd773ca315748df78a16071e2802","functions":[{"id":"func/Profiles.constructor","name":"Profiles.constructor","line":13,"end_line":19,"hash":"247804207ec0220b6e6507f6beb6f86023a7c08b50737a52a0dbb99d262993d3"},{"id":"func/Profiles.setName","name":"Profiles.setName","line":21,"end_line":24,"hash":"5a36c6e237798608de0bedd8744b75000c0eec5c0a6a64c870a25bcdf20aed21"},{"id":"func/Profiles.getName","name":"Profiles.getName","line":26,"end_line":29,"hash":"2fcb9d84687ea0f3b24f3e34c0a72eda55a4e869b87e08a7f4551321a4166198"},{"id":"func/Profiles.setBio","name":"Profiles.setBio","line":31,"end_line":34,"hash":"3825665ead1ba9bb217694c45a17bb2e11c78ffa053e5e90111a4b9208183b56"},{"id":"func/Profiles.getBio","name":"Profiles.getBio","line":36,"end_line":39,"hash":"2e9708249db4a0e4fa642cbe52e6216144ec91283281c61dee2ff3cc3d8f1572"},{"id":"func/Profiles.setAvatarUrl","name":"Profiles.setAvatarUrl","line":41,"end_line":44,"hash":"e4ccb0164fee4ab6cc3a1290fb4bf85e4a79f2227ca72872b1f10bc616926fd9"},{"id":"func/Profiles.getAvatarUrl","name":"Profiles.getAvatarUrl","line":46,"end_line":49,"hash":"0aa58dc15fd519e553136d04d1954e18084f79a6cd9349dc89b1136cf0a22a2b"},{"id":"func/Profiles.setFollowState","name":"Profiles.setFollowState","line":52,"end_line":54,"hash":"805cafb46052f91bfa0a123842c25ff8ee0f7f4a7e661f51d289b0487738dbd4"},{"id":"func/Profiles.getFollowState","name":"Profiles.getFollowState","line":56,"end_line":58,"hash":"48fdf5a632825946c391146628cd6f51b4eb0169c7a6d6b89c795ff554e62b07"},{"id":"func/Profiles.setTopicFollowState","name":"Profiles.setTopicFollowState","line":61,"end_line":63,"hash":"54ab980e42018d64fbacee7d80347d530791b7ba21d8fac46f5ed85f33903f98"},{"id":"func/Profiles.getTopicFollowState","name":"Profiles.getTopicFollowState","line":65,"end_line":67,"hash":"90ce88799dda5477e20ce4de17404dace55abf1d2f2c1c87671e94fc2f270205"},{"id":"func/Profiles._setMapState","name":"Profiles._setMapState","line":70,"end_line":76,"hash":"13d2cad84be961b89482970f55f107d93fa1bdc10636dc64844c6a9263e88583"},{"id":"func/Profiles._getMapState","name":"Profiles._getMapState","line":79,"end_line":82,"hash":"c1c8966a797533614d35c7a13deb8f757572127ebcbde1d234c7d966346d89a8"}]}
 // mutate4javascript-manifest-end

psf-memo-client/test/property/topic-post.property.test.js

@@ -0,0 +1,79 @@
+/*
+  Property tests for the Memo topic-post byte accounting.
+
+  The unit tests probe isTooLong and remainingBytes at a few fixed fixtures.
+  These properties pin down invariants that hold over broad random UTF-8
+  inputs (mixed byte widths):
+
+    - byte accounting: remainingBytes(msg) always equals the combined byte
+      budget minus the room and message byte lengths.
+    - consistency: isTooLong(msg) is true exactly when remainingBytes(msg)
+      is negative.
+    - monotonicity: appending bytes never flips a too-long message back to
+      being accepted.
+*/
+
+'use strict'
+
+const test = require('node:test')
+const { seededRandom, forAll } = require('./harness')
+const MemoTopicPost = require('../../src/services/memo-topic-post')
+const { byteLength } = require('../../src/services/utf8')
+
+const rng = seededRandom(20260901)
+const MAX = MemoTopicPost.MAX_TOPIC_MESSAGE_BYTES
+
+// Characters with distinct UTF-8 byte widths: 1, 1, 1, 2, 3, and 4 bytes.
+const CHARS = ['a', 'b', ' ', '\u00e9', '\u20ac', '\ud83d\ude00']
+
+function textGen () {
+  const len = Math.floor(rng() * 140)
+  let out = ''
+  for (let i = 0; i < len; i++) {
+    out += CHARS[Math.floor(rng() * CHARS.length)]
+  }
+  return out
+}
+
+function postInputGen () {
+  return () => ({ room: textGen(), msg: textGen() })
+}
+
+test('remainingBytes equals the byte budget minus room and message bytes', async () => {
+  await forAll(
+    postInputGen(),
+    ({ room, msg }) => {
+      const post = new MemoTopicPost({ room })
+      return post.remainingBytes(msg) === MAX - byteLength(room) - byteLength(msg)
+    },
+    { label: 'remainingBytes byte accounting' }
+  )
+})
+
+test('isTooLong is true exactly when remainingBytes is negative', async () => {
+  await forAll(
+    postInputGen(),
+    ({ room, msg }) => {
+      const post = new MemoTopicPost({ room })
+      return post.isTooLong(msg) === (post.remainingBytes(msg) < 0)
+    },
+    { label: 'isTooLong / remainingBytes consistency' }
+  )
+})
+
+test('isTooLong is monotonic as message bytes are appended', async () => {
+  await forAll(
+    () => {
+      const { room, msg } = postInputGen()()
+      const extra = textGen()
+      return { room, msg, extra }
+    },
+    ({ room, msg, extra }) => {
+      const post = new MemoTopicPost({ room })
+      // Appending bytes can only make a message longer, so a too-long
+      // message must remain too-long once more bytes are added.
+      return !(post.isTooLong(msg) && !post.isTooLong(msg + extra))
+    },
+    { label: 'isTooLong monotonicity' }
+  )
+})

psf-memo-client/test/property/topic-services.property.test.js

@@ -64,7 +64,10 @@ test('TopicFeedPage.getPost finds any loaded post', async () => {
       return posts
     },
     async (posts) => {
-      const memoDb = { async getTopicPosts () { return { posts, pagination: { total: posts.length } } } }
+      const memoDb = {
+        async getTopicPosts () { return { posts, pagination: { total: posts.length } } },
+        async getTopicFollowers () { return [] }
+      }
       const page = new TopicFeedPage({ memoDb, room: 'bitcoin' })
       await page.load()
 

psf-memo-client/test/unit/profiles.test.js

@@ -134,6 +134,64 @@ test('follow state storage is independent per self address', () => {
   assert.equal(profiles.getFollowState(otherSelfAddr, targetAddr), false)
 })
 
+test('setTopicFollowState stores and getTopicFollowState retrieves topic follow state', () => {
+  const profiles = new Profiles()
+  const selfAddr = 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d'
+  const room = 'bitcoin'
+
+  profiles.setTopicFollowState(selfAddr, room, true)
+
+  assert.equal(profiles.getTopicFollowState(selfAddr, room), true)
+})
+
+test('getTopicFollowState returns false for an unknown topic relationship', () => {
+  const profiles = new Profiles()
+  const selfAddr = 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d'
+
+  assert.equal(profiles.getTopicFollowState(selfAddr, 'bitcoin'), false)
+})
+
+test('setTopicFollowState with no self address does nothing', () => {
+  const profiles = new Profiles()
+
+  profiles.setTopicFollowState('', 'bitcoin', true)
+
+  assert.equal(profiles.getTopicFollowState('', 'bitcoin'), false)
+})
+
+test('setTopicFollowState with no room does nothing', () => {
+  const profiles = new Profiles()
+  const selfAddr = 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d'
+
+  profiles.setTopicFollowState(selfAddr, '', true)
+
+  assert.equal(profiles.getTopicFollowState(selfAddr, ''), false)
+})
+
+test('topic follow state storage is independent per self address', () => {
+  const profiles = new Profiles()
+  const selfAddr = 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d'
+  const otherSelfAddr = 'bitcoincash:qpm2qsznhks23z7629mms6s4cwef74vcwvy22gdx6a'
+
+  profiles.setTopicFollowState(selfAddr, 'bitcoin', true)
+  profiles.setTopicFollowState(otherSelfAddr, 'bitcoin', false)
+
+  assert.equal(profiles.getTopicFollowState(selfAddr, 'bitcoin'), true)
+  assert.equal(profiles.getTopicFollowState(otherSelfAddr, 'bitcoin'), false)
+})
+
+test('topic follow state storage is independent of address follow state', () => {
+  const profiles = new Profiles()
+  const selfAddr = 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d'
+  const targetAddr = 'bitcoincash:qr95sy3j9xwd2ap32xkykttr4cvcu7as4y0qverfuy'
+
+  profiles.setFollowState(selfAddr, targetAddr, true)
+  profiles.setTopicFollowState(selfAddr, 'bitcoin', true)
+
+  assert.equal(profiles.getFollowState(selfAddr, targetAddr), true)
+  assert.equal(profiles.getTopicFollowState(selfAddr, 'bitcoin'), true)
+})
+
 test('avatar URL storage is independent of name and bio storage', () => {
   const profiles = new Profiles()
   const addr = 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d'