Refactor memo actions and page controllers to share base classes

Extract MemoAction and PageController base classes to remove structural
duplication between the memo post/set-name actions and the new post/set-name
page controllers. Add property tests for the set-name byte counter and
validation invariants. Refresh mutation manifests for the refactored files.

By refactorer.

src/services/memo-action.js

@@ -0,0 +1,70 @@
+/*
+  Shared base for Memo protocol actions that broadcast an OP_RETURN
+  transaction through a wallet and reflect the result on an injected store.
+
+  Subclasses supply the protocol-specific pieces:
+    prefix            - hex protocol prefix (e.g. 0x6d02 for a post)
+    walletRequiredMsg - error message when no wallet is present
+    lengthMessage     - error text for an over-length value
+    emptyMessage      - error text for an empty value
+    lengthCode        - error code for an over-length value
+    validationCode    - error code for an empty value
+    isTooLong(value)  - true when the value exceeds the action's limit
+    reflect(txid, value) - record the broadcast result on the injected store
+*/
+
+class MemoAction {
+  constructor (deps = {}) {
+    this.wallet = deps.wallet
+  }
+
+  // Validate a candidate value.
+  // Returns { ok: true } or { ok: false, type: 'validation' | 'length' }.
+  validate (value) {
+    if (typeof value !== 'string' || value.trim().length === 0) {
+      return { ok: false, type: 'validation' }
+    }
+
+    if (this.isTooLong(value)) {
+      return { ok: false, type: 'length' }
+    }
+
+    return { ok: true }
+  }
+
+  // Compose and broadcast the action for the given value.
+  // Resolves with the transaction id, or rejects with a typed error.
+  async broadcast (value) {
+    const check = this.validate(value)
+    this._throwIfInvalid(check)
+
+    if (!this.wallet) {
+      throw new Error(this.walletRequiredMsg)
+    }
+
+    // Refresh the wallet's spendable UTXO store so the broadcast has inputs.
+    await this.wallet.getUtxos()
+
+    // The wallet's public sendOpReturn(msg, prefix) resolves walletInfo and its
+    // own spendable UTXOs internally, so only the value and prefix are passed.
+    const txid = await this.wallet.sendOpReturn(value, this.prefix)
+
+    // Reflect the result on the injected store once broadcast succeeds.
+    this.reflect(txid, value)
+
+    return txid
+  }
+
+  // Throw the appropriate typed error when a value fails validation.
+  _throwIfInvalid (check) {
+    if (check.ok) return
+
+    const err = new Error(
+      check.type === 'length' ? this.lengthMessage : this.emptyMessage
+    )
+    err.code = check.type === 'length' ? this.lengthCode : this.validationCode
+    throw err
+  }
+}
+
+module.exports = MemoAction

src/services/memo-post.js

@@ -16,68 +16,36 @@
                        218 rejected)
 */
 
+const MemoAction = require('./memo-action')
+
 const MEMO_POST_PREFIX = '6d02'
 const MAX_MEMO_CHARS = 217
 
-class MemoPost {
+class MemoPost extends MemoAction {
   constructor (deps = {}) {
-    this.wallet = deps.wallet
+    super(deps)
     this.feed = deps.feed
+    this.prefix = MEMO_POST_PREFIX
+    this.walletRequiredMsg = 'Memo post requires a wallet.'
+    this.lengthMessage = `Memo is too long. Maximum is ${MAX_MEMO_CHARS} characters.`
+    this.emptyMessage = 'Memo must not be empty.'
+    this.lengthCode = 'memo_length'
+    this.validationCode = 'memo_validation'
   }
 
-  // Validate a candidate memo message.
+  // A memo is over-length when it exceeds the character limit.
-  // Returns { ok: true } or { ok: false, type: 'validation' | 'length' }.
+  isTooLong (message) {
-  validate (message) {
+    return message.length > MAX_MEMO_CHARS
-    if (typeof message !== 'string' || message.trim().length === 0) {
-      return { ok: false, type: 'validation' }
-    }
-
-    if (message.length > MAX_MEMO_CHARS) {
-      return { ok: false, type: 'length' }
-    }
-
-    return { ok: true }
   }
 
   // Compose and broadcast a Memo post for the given message.
   // Resolves with the transaction id, or rejects with a typed error.
   async post (message) {
-    const check = this.validate(message)
+    return this.broadcast(message)
-    this._throwIfInvalid(check)
-
-    if (!this.wallet) {
-      throw new Error('Memo post requires a wallet.')
-    }
-
-    // Refresh the wallet's spendable UTXO store so the broadcast has inputs.
-    await this.wallet.getUtxos()
-
-    // The wallet's public sendOpReturn(msg, prefix) resolves walletInfo and
-    // its own spendable UTXOs internally, so only the message and Memo post
-    // prefix are passed here.
-    const txid = await this.wallet.sendOpReturn(message, MEMO_POST_PREFIX)
-
-    // Reflect the new post in the feed once broadcast succeeds.
-    this._reflectPost(txid, message)
-
-    return txid
-  }
-
-  // Throw the appropriate typed error when a memo fails validation.
-  _throwIfInvalid (check) {
-    if (check.ok) return
-
-    const err = new Error(
-      check.type === 'length'
-        ? `Memo is too long. Maximum is ${MAX_MEMO_CHARS} characters.`
-        : 'Memo must not be empty.'
-    )
-    err.code = check.type === 'length' ? 'memo_length' : 'memo_validation'
-    throw err
   }
 
   // Record the new post on the injected feed when one is present.
-  _reflectPost (txid, message) {
+  reflect (txid, message) {
     if (this.feed && typeof this.feed.addPost === 'function') {
       this.feed.addPost({
         txid,
@@ -94,5 +62,5 @@ MemoPost.MAX_MEMO_CHARS = MAX_MEMO_CHARS
 module.exports = MemoPost
 
 // mutate4javascript-manifest-begin
-// {"version":1,"tested_at":"2026-08-26T00:06:35.333Z","module_hash":"600c2edb145b16db5e313a2911fe164a2c08731346f2a67f52bca18827d8081e","functions":[{"id":"func/MemoPost.constructor","name":"MemoPost.constructor","line":23,"end_line":26,"hash":"73596685cdf614a4aa3bb3ab2ee2eec1c080e41ef8c56053a521eb07ca5c7d48"},{"id":"func/MemoPost.validate","name":"MemoPost.validate","line":30,"end_line":40,"hash":"2e45fb32d480e36e04ac61c3fb414849d9daa640c5ac366ee1363be4c3903fd0"},{"id":"func/MemoPost.post","name":"MemoPost.post","line":44,"end_line":67,"hash":"6a817a7eceb24e9e4eb9689345ea3ef6456e8b872bff00a0587bddae8060ead2"},{"id":"func/MemoPost._throwIfInvalid","name":"MemoPost._throwIfInvalid","line":70,"end_line":80,"hash":"e01932c7c343519cc8dd52d3e29b695783c6cdb7e84368e193140827c26bb39c"},{"id":"func/MemoPost._reflectPost","name":"MemoPost._reflectPost","line":83,"end_line":91,"hash":"36e9b77ac19b8a0c598e02f438c3d2ac1f6b7495cf6e28d9546d064ce63f861a"}]}
+// {"version":1,"tested_at":"2026-08-26T02:54:15.221Z","module_hash":"7060e3997af5f6340180385c1e96e055614280683bffdeb737e49c37ad6ce946","functions":[{"id":"func/MemoPost.constructor","name":"MemoPost.constructor","line":25,"end_line":34,"hash":"f1843343deb758b304364862c2c58af3a8a5b03e3d8a70f3056c8679e869a9ed"},{"id":"func/MemoPost.isTooLong","name":"MemoPost.isTooLong","line":37,"end_line":39,"hash":"833f9f66eae849df0248d0c696c95c767a121b394b1c728bc3ec675668dff5de"},{"id":"func/MemoPost.post","name":"MemoPost.post","line":43,"end_line":45,"hash":"26d8e84b520fae1928f7f72215e6ed95f7219c14266c99b710e2af5373cb6faf"},{"id":"func/MemoPost.reflect","name":"MemoPost.reflect","line":48,"end_line":56,"hash":"87e2168a71309a572c60b63f382dd6f681cb28ed543090dbde399e29556cfcdf"}]}
 // mutate4javascript-manifest-end

src/services/memo-set-name.js

@@ -16,65 +16,36 @@
     MAX_NAME_BYTES       : maximum allowed name length (77 bytes per memo.sv)
 */
 
+const MemoAction = require('./memo-action')
+
 const MEMO_SET_NAME_PREFIX = '6d01'
 const MAX_NAME_BYTES = 77
 
-class MemoSetName {
+class MemoSetName extends MemoAction {
   constructor (deps = {}) {
-    this.wallet = deps.wallet
+    super(deps)
     this.profiles = deps.profiles
+    this.prefix = MEMO_SET_NAME_PREFIX
+    this.walletRequiredMsg = 'Memo set name requires a wallet.'
+    this.lengthMessage = `Name is too long. Maximum is ${MAX_NAME_BYTES} bytes.`
+    this.emptyMessage = 'Name must not be empty.'
+    this.lengthCode = 'name_length'
+    this.validationCode = 'name_validation'
   }
 
-  // Validate a candidate name.
+  // A name is over-length when it exceeds the byte limit.
-  // Returns { ok: true } or { ok: false, type: 'validation' | 'length' }.
+  isTooLong (name) {
-  validate (name) {
+    return Buffer.byteLength(name, 'utf8') > MAX_NAME_BYTES
-    if (typeof name !== 'string' || name.trim().length === 0) {
-      return { ok: false, type: 'validation' }
-    }
-
-    if (Buffer.byteLength(name, 'utf8') > MAX_NAME_BYTES) {
-      return { ok: false, type: 'length' }
-    }
-
-    return { ok: true }
   }
 
   // Compose and broadcast a Memo set-name transaction for the given name.
   // Resolves with the transaction id, or rejects with a typed error.
   async setName (name) {
-    const check = this.validate(name)
+    return this.broadcast(name)
-    this._throwIfInvalid(check)
-
-    if (!this.wallet) {
-      throw new Error('Memo set name requires a wallet.')
-    }
-
-    // Refresh the wallet's spendable UTXO store so the broadcast has inputs.
-    await this.wallet.getUtxos()
-
-    const txid = await this.wallet.sendOpReturn(name, MEMO_SET_NAME_PREFIX)
-
-    // Reflect the new name in the injected profile store once broadcast succeeds.
-    this._reflectName(name)
-
-    return txid
-  }
-
-  // Throw the appropriate typed error when a name fails validation.
-  _throwIfInvalid (check) {
-    if (check.ok) return
-
-    const err = new Error(
-      check.type === 'length'
-        ? `Name is too long. Maximum is ${MAX_NAME_BYTES} bytes.`
-        : 'Name must not be empty.'
-    )
-    err.code = check.type === 'length' ? 'name_length' : 'name_validation'
-    throw err
   }
 
   // Record the new name on the injected profile store when one is present.
-  _reflectName (name) {
+  reflect (txid, name) {
     if (this.profiles && typeof this.profiles.setName === 'function') {
       this.profiles.setName(this.wallet.walletInfo.cashAddress, name)
     }

src/services/new-post.js

@@ -13,21 +13,20 @@
   adapter boundaries.
 */
 
+const PageController = require('./page-controller')
 const MemoPost = require('./memo-post')
 
 const NEW_POST_PATH = '/posts/new'
 const RECENT_FEED_PATH = '/posts/recent'
 
-class NewPostPage {
+class NewPostPage extends PageController {
   constructor (deps = {}) {
+    super(deps)
     this.memoPost = deps.memoPost || null
-    this.navigate = deps.navigate || (() => {})
     this.menuLinks = deps.menuLinks || []
-
-    this.input = ''
-    this.submitError = null
-    this.broadcastError = null
     this.posting = false
+    this.successPath = RECENT_FEED_PATH
+    this.validationCodes = ['memo_validation', 'memo_length']
 
     // The navigation menu links to the new post page.
     this.addMenuLink(NEW_POST_PATH)
@@ -44,51 +43,22 @@ class NewPostPage {
     return this.menuLinks.includes(path)
   }
 
-  // Set the draft memo text and update the counter.
-  setInput (text) {
-    this.input = typeof text === 'string' ? text : ''
-    return this
-  }
-
   // Characters remaining before the memo limit is reached.
   remainingCount () {
     return MemoPost.MAX_MEMO_CHARS - this.input.length
   }
 
-  // Validate and post the current draft. On success, navigate to the recent
+  // Set the in-flight posting flag.
-  // feed. On failure, record the typed error and stay on the page. Resolves
+  _setBusy (value) {
-  // with a result object.
+    this.posting = value
-  async submit () {
-    this.posting = true
-    this.submitError = null
-    this.broadcastError = null
-
-    try {
-      if (!this.memoPost) {
-        throw new Error('New post requires a memo post handler.')
-      }
-
-      const txid = await this.memoPost.post(this.input)
-      this.navigate(RECENT_FEED_PATH)
-      this.posting = false
-      return { ok: true, txid }
-    } catch (err) {
-      return this._handleSubmitFailure(err)
-    }
   }
 
-  // Classify a submit failure, record the typed state, and return the failure
+  // Run the memo post action for the current input.
-  // result. Local validation failures set submitError; broadcast or handler
+  async _perform (input) {
-  // failures surface the real error message via broadcastError.
+    if (!this.memoPost) {
-  _handleSubmitFailure (err) {
+      throw new Error('New post requires a memo post handler.')
-    if (err.code === 'memo_validation' || err.code === 'memo_length') {
-      this.submitError = err.code
-    } else {
-      this.broadcastError = err.message || String(err)
-      this.submitError = 'broadcast'
     }
-    this.posting = false
+    return this.memoPost.post(input)
-    return { ok: false, error: this.submitError, message: this.broadcastError }
   }
 }
 
@@ -98,5 +68,5 @@ NewPostPage.RECENT_FEED_PATH = RECENT_FEED_PATH
 module.exports = NewPostPage
 
 // mutate4javascript-manifest-begin
-// {"version":1,"tested_at":"2026-08-26T00:39:54.163Z","module_hash":"8d50d002e9c6094a1bd2d6e764023c942b1eb0f085b019255dc80f0a72ab1ec6","functions":[{"id":"func/NewPostPage.constructor","name":"NewPostPage.constructor","line":22,"end_line":34,"hash":"d61d01986c51dc4ed4185594fa3e35612924846db321a7107aaec191d17c419d"},{"id":"func/NewPostPage.addMenuLink","name":"NewPostPage.addMenuLink","line":37,"end_line":40,"hash":"bac97164d2d70bfdb946c4d54e67983c43cad093bac558f1d169e1739ca97137"},{"id":"func/NewPostPage.hasMenuLink","name":"NewPostPage.hasMenuLink","line":43,"end_line":45,"hash":"7e1abf5d0833aaf3b3da3a024de9eb2b80da900b2930e832c7e92d77e0e50344"},{"id":"func/NewPostPage.setInput","name":"NewPostPage.setInput","line":48,"end_line":51,"hash":"595484662b7ca07ef5eef5cebbff06309242552d9b4d15687df02f260ba88244"},{"id":"func/NewPostPage.remainingCount","name":"NewPostPage.remainingCount","line":54,"end_line":56,"hash":"521ce4ed841f62099529b327f2245a9e94c09af2f67ed5d91839e52607bcea37"},{"id":"func/NewPostPage.submit","name":"NewPostPage.submit","line":61,"end_line":78,"hash":"c280ee1244bcb80c3a9ffe4f52befc8a05629ec879ef9d86666ea11f493b3c5b"},{"id":"func/NewPostPage._handleSubmitFailure","name":"NewPostPage._handleSubmitFailure","line":83,"end_line":92,"hash":"b13d8cd6b48b1f42d72e0031cabcaa00bb78b813f42250517d711f0d6fb23126"}]}
+// {"version":1,"tested_at":"2026-08-26T02:54:16.145Z","module_hash":"45d772cfe40b8a34018092abbe924c01cbde741c5cbaa737a283ba35214a99ff","functions":[{"id":"func/NewPostPage.constructor","name":"NewPostPage.constructor","line":23,"end_line":33,"hash":"686653c181941b27c19cd8c1f9fa7b3fee50db6e19c1e39d0db79e6bfbe52a81"},{"id":"func/NewPostPage.addMenuLink","name":"NewPostPage.addMenuLink","line":36,"end_line":39,"hash":"bac97164d2d70bfdb946c4d54e67983c43cad093bac558f1d169e1739ca97137"},{"id":"func/NewPostPage.hasMenuLink","name":"NewPostPage.hasMenuLink","line":42,"end_line":44,"hash":"7e1abf5d0833aaf3b3da3a024de9eb2b80da900b2930e832c7e92d77e0e50344"},{"id":"func/NewPostPage.remainingCount","name":"NewPostPage.remainingCount","line":47,"end_line":49,"hash":"521ce4ed841f62099529b327f2245a9e94c09af2f67ed5d91839e52607bcea37"},{"id":"func/NewPostPage._setBusy","name":"NewPostPage._setBusy","line":52,"end_line":54,"hash":"af4c51d75a9bbfc4d8c2566414ee950704d83831ad915ee04eea8bf2fab65a3e"},{"id":"func/NewPostPage._perform","name":"NewPostPage._perform","line":57,"end_line":62,"hash":"e66f893a4913b5d6f3cc4fcc1ad58e21557b4a316f0150050c961e3ece237795"}]}
 // mutate4javascript-manifest-end

src/services/page-controller.js

@@ -0,0 +1,59 @@
+/*
+  Shared base for page controllers that compose and submit a single action,
+  surface validation/broadcast errors, and navigate on success.
+
+  Subclasses supply the page-specific pieces:
+    successPath      - path to navigate to on success
+    validationCodes  - error codes that represent local validation failures
+    _setBusy(value)  - set the page's in-flight flag
+    _perform(input)  - run the action for the current input, resolving with txid
+*/
+
+class PageController {
+  constructor (deps = {}) {
+    this.navigate = deps.navigate || (() => {})
+    this.input = ''
+    this.submitError = null
+    this.broadcastError = null
+  }
+
+  // Set the draft input.
+  setInput (text) {
+    this.input = typeof text === 'string' ? text : ''
+    return this
+  }
+
+  // Validate and submit the current input. On success, navigate to the success
+  // path. On failure, record the typed error and stay on the page. Resolves
+  // with a result object.
+  async submit () {
+    this._setBusy(true)
+    this.submitError = null
+    this.broadcastError = null
+
+    try {
+      const txid = await this._perform(this.input)
+      this.navigate(this.successPath)
+      this._setBusy(false)
+      return { ok: true, txid }
+    } catch (err) {
+      return this._handleSubmitFailure(err)
+    }
+  }
+
+  // Classify a submit failure, record the typed state, and return the failure
+  // result. Local validation failures set submitError; broadcast or handler
+  // failures surface the real error message via broadcastError.
+  _handleSubmitFailure (err) {
+    if (this.validationCodes.includes(err.code)) {
+      this.submitError = err.code
+    } else {
+      this.broadcastError = err.message || String(err)
+      this.submitError = 'broadcast'
+    }
+    this._setBusy(false)
+    return { ok: false, error: this.submitError, message: this.broadcastError }
+  }
+}
+
+module.exports = PageController

src/services/set-name-page.js

@@ -13,26 +13,19 @@
   adapter boundaries.
 */
 
+const PageController = require('./page-controller')
 const MemoSetName = require('./memo-set-name')
 
 const SET_NAME_PATH = '/memo/set-name'
 const ACCOUNT_PATH = '/account'
 
-class SetNamePage {
+class SetNamePage extends PageController {
   constructor (deps = {}) {
+    super(deps)
     this.memoSetName = deps.memoSetName || null
-    this.navigate = deps.navigate || (() => {})
-
-    this.input = ''
-    this.submitError = null
-    this.broadcastError = null
     this.settingName = false
-  }
+    this.successPath = ACCOUNT_PATH
-
+    this.validationCodes = ['name_validation', 'name_length']
-  // Set the draft name and update the counter.
-  setInput (text) {
-    this.input = typeof text === 'string' ? text : ''
-    return this
   }
 
   // Bytes remaining before the name limit is reached.
@@ -40,40 +33,17 @@ class SetNamePage {
     return MemoSetName.MAX_NAME_BYTES - Buffer.byteLength(this.input, 'utf8')
   }
 
-  // Validate and broadcast the current draft name. On success, navigate to the
+  // Set the in-flight setting-name flag.
-  // account page. On failure, record the typed error and stay on the page.
+  _setBusy (value) {
-  // Resolves with a result object.
+    this.settingName = value
-  async submit () {
-    this.settingName = true
-    this.submitError = null
-    this.broadcastError = null
-
-    try {
-      if (!this.memoSetName) {
-        throw new Error('Set name requires a memo set-name handler.')
-      }
-
-      const txid = await this.memoSetName.setName(this.input)
-      this.navigate(ACCOUNT_PATH)
-      this.settingName = false
-      return { ok: true, txid }
-    } catch (err) {
-      return this._handleSubmitFailure(err)
-    }
   }
 
-  // Classify a submit failure, record the typed state, and return the failure
+  // Run the memo set-name action for the current input.
-  // result. Local validation failures set submitError; broadcast or handler
+  async _perform (input) {
-  // failures surface the real error message via broadcastError.
+    if (!this.memoSetName) {
-  _handleSubmitFailure (err) {
+      throw new Error('Set name requires a memo set-name handler.')
-    if (err.code === 'name_validation' || err.code === 'name_length') {
-      this.submitError = err.code
-    } else {
-      this.broadcastError = err.message || String(err)
-      this.submitError = 'broadcast'
     }
-    this.settingName = false
+    return this.memoSetName.setName(input)
-    return { ok: false, error: this.submitError, message: this.broadcastError }
   }
 }
 

test/property/set-name.property.test.js

@@ -0,0 +1,146 @@
+/*
+  Property tests for the Set Name behavior slice.
+
+  These assert useful invariants that unit tests cover only at a few fixed
+  points:
+    - Set-name validation classification is stable across a broad input range:
+      any non-blank string up to the byte limit is accepted, any longer string
+      is rejected with a length error, and blank/non-string input is a
+      validation error.
+    - The Set Name byte counter conserves its relationship to input byte
+      length: Buffer.byteLength(input) + remainingCount() === MAX_NAME_BYTES
+      for any string.
+    - setInput round-trips the exact draft text.
+    - A broadcast failure surfaces the error and never navigates.
+*/
+
+'use strict'
+
+const test = require('node:test')
+
+const { seededRandom, forAll, makeStringGen } = require('./harness')
+
+const MemoSetName = require('../../src/services/memo-set-name')
+const SetNamePage = require('../../src/services/set-name-page')
+
+const MAX = MemoSetName.MAX_NAME_BYTES // 77
+
+const rng = seededRandom(20260827)
+const stringOf = makeStringGen(rng)
+
+function buildPage () {
+  return new SetNamePage({
+    memoSetName: new MemoSetName({}),
+    navigate: () => {}
+  })
+}
+
+// A fake wallet recording broadcast attempts; fails when failWith is set.
+function fakeWallet () {
+  const wallet = {
+    walletInfo: { cashAddress: 'bitcoincash:qqlrzp23w08434twmvr4fxw672whkjy0py26r63g3d' },
+    utxos: [{ txid: 'utxo-fee' }],
+    getUtxos: async function () { return this.utxos },
+    sendOpReturn: async function (msg, prefix) {
+      if (this.failWith) throw new Error(this.failWith)
+      return 'prop-txid'
+    }
+  }
+  return wallet
+}
+
+function fakeProfiles () {
+  const names = new Map()
+  return {
+    names,
+    setName: (addr, name) => names.set(addr, name),
+    getName: (addr) => names.get(addr) || null
+  }
+}
+
+test('set-name validation: any non-blank string at or below the byte limit is valid', async () => {
+  await forAll(
+    (i) => {
+      const len = 1 + Math.floor(rng() * MAX) // 1..MAX
+      return stringOf(len)
+    },
+    (name) => {
+      // A random ASCII string may occasionally be all whitespace; whitespace-only
+      // input is a validation error, so only assert for non-blank strings.
+      if (name.trim().length === 0) return true
+      const result = new MemoSetName({}).validate(name)
+      return result.ok === true
+    },
+    { label: 'valid byte length' }
+  )
+})
+
+test('set-name validation: any string above the byte limit is a length error', async () => {
+  await forAll(
+    (i) => stringOf(MAX + 1 + Math.floor(rng() * 100)), // > MAX
+    (name) => {
+      const result = new MemoSetName({}).validate(name)
+      return result.ok === false && result.type === 'length'
+    },
+    { label: 'over-long rejected as length' }
+  )
+})
+
+test('set-name validation: blank and non-string input are validation errors', async () => {
+  await forAll(
+    (i) => (i % 2 === 0 ? '   ' : null),
+    (name) => {
+      const result = new MemoSetName({}).validate(name)
+      return result.ok === false && result.type === 'validation'
+    },
+    { label: 'blank/non-string rejected as validation' }
+  )
+})
+
+test('byte counter conserves byte length: remaining === MAX - byteLength(input)', async () => {
+  await forAll(
+    (i) => stringOf(Math.floor(rng() * (MAX + 8))),
+    (name) => {
+      const page = buildPage()
+      page.setInput(name)
+      return page.remainingCount() === MAX - Buffer.byteLength(name, 'utf8')
+    },
+    { label: 'byte counter conservation' }
+  )
+})
+
+test('setInput round-trips the draft text exactly', async () => {
+  await forAll(
+    (i) => stringOf(Math.floor(rng() * 50)),
+    (name) => {
+      const page = buildPage()
+      page.setInput(name)
+      return page.input === name
+    },
+    { label: 'setInput round-trip' }
+  )
+})
+
+test('a broadcast failure surfaces the error and never navigates', async () => {
+  await forAll(
+    (i) => ({ name: stringOf(1 + Math.floor(rng() * 40)), failWith: `boom-${i % 97}` }),
+    ({ name, failWith }) => {
+      const wallet = fakeWallet()
+      wallet.failWith = failWith
+      const navigations = []
+      const page = new SetNamePage({
+        memoSetName: new MemoSetName({ wallet, profiles: fakeProfiles() }),
+        navigate: (p) => navigations.push(p)
+      })
+      page.setInput(name)
+
+      return page.submit().then((result) => {
+        if (result.ok) return false
+        if (page.submitError !== 'broadcast') return false
+        if (!page.broadcastError || !page.broadcastError.includes('boom')) return false
+        return navigations.length === 0
+      })
+    },
+    { label: 'broadcast failure does not navigate' }
+  )
+})