From 670497f5cbae95431b1f99c0410973487c2bc968 Mon Sep 17 00:00:00 2001
From: Danyang Chen <birfychen@gmail.com>
Date: Sat, 7 Nov 2026 14:33:35 +0800
Subject: [PATCH] Cut task cues, failure text, shares and labels on code points
 (#2581)

Docs-not-needed: the fix routes existing bounds through code-point cuts and the existing cut() helper; no owned interface, tool, flow or stored shape changes.
---
 changelog.d/2581-utf16-cut.fixed.md           |  1 +
 core/src/host/task-drive.js                   |  5 ++-
 core/src/shared/text-boundary.js              |  5 +++
 core/test/task-drive.test.js                  | 15 +++++++
 patches/ds-bot/files/src/host/task-drive.js   |  5 ++-
 .../ds-bot/files/src/shared/text-boundary.js  |  5 +++
 patches/ds-bot/files/test/task-drive.test.js  | 15 +++++++
 plugins/social/src/social.js                  | 10 ++++-
 plugins/social/test/social.test.js            | 35 ++++++++++++++++
 plugins/timeline/src/sanitize.js              | 12 +++++-
 plugins/timeline/test/sanitize.test.js        | 13 ++++++
 plugins/workflow/client.js                    | 18 +++++---
 plugins/workflow/src/graph.js                 | 10 +++++
 plugins/workflow/src/service.js               |  9 +++-
 plugins/workflow/test/client.test.js          | 41 +++++++++++++++++++
 plugins/workflow/test/code-point-cut.test.js  | 28 +++++++++++++
 plugins/workflow/test/graph.test.js           | 13 +++++-
 17 files changed, 226 insertions(+), 14 deletions(-)
 create mode 100644 changelog.d/2581-utf16-cut.fixed.md
 create mode 100644 plugins/workflow/test/code-point-cut.test.js

diff --git a/changelog.d/2581-utf16-cut.fixed.md b/changelog.d/2581-utf16-cut.fixed.md
new file mode 100644
index 000000000..773508700
--- /dev/null
+++ b/changelog.d/2581-utf16-cut.fixed.md
@@ -0,0 +1 @@
+Workflow failure text, task cues, co-seat room shares, workflow avatars and role lines, and timeline labels now cut on character boundaries instead of UTF-16 units, so an emoji is never split into a half character and rendered as a replacement character ([#2581](https://github.com/ThinkFlowLab/FlyBot/issues/2581)).
diff --git a/core/src/host/task-drive.js b/core/src/host/task-drive.js
index b40bc8555..cc79c21ae 100644
--- a/core/src/host/task-drive.js
+++ b/core/src/host/task-drive.js
@@ -5,6 +5,7 @@
 // open a group Session and does not post the reply into the room. Assigning,
 // progress, and the next assignee are board writes; chat is not the scheduler.
 import { compareForQueue, compareForWork, occupiesSlot, sameRole } from '../shared/task-board.js'
+import { cut } from '../shared/text-boundary.js'
 import { formatRoomBoard } from './room-context.js'
 import { retiredBot } from './store.js'
 
@@ -34,7 +35,7 @@ const fingerprint = (tasks) => tasks.map(task => [
 // A queue item is offered, not owned: this cue names the item and the claim, never its note —
 // the note is the body, and reading it is the turn's job, not the wake's (#1247).
 const queueCueFor = (task) => {
-  const title = String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim().slice(0, 200)
+  const title = cut(String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim(), 200).text
   const priority = task.priority ?? 'normal'
   return `Take ${task.id} [${priority}] ${title} — queued for ${task.queueRole}. Claim it with track_tasks {claim: true, id: '${task.id}'}, then set its column to in-progress. Do not post a status in the group. Stop when it is done or waiting on an answer. Do not invent other work.`
 }
@@ -51,7 +52,7 @@ const queueFingerprint = (task) => (task === undefined ? '' : [
 ].join('\u0000'))
 
 const cueFor = (task) => {
-  const title = String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim().slice(0, 200)
+  const title = cut(String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim(), 200).text
   const priority = task.priority ?? 'normal'
   const post = task.writeBack?.state === 'pending'
     ? ` Then post the decision comment on ${task.writeBack.target} with your GitHub connector and record it with track_tasks postResult {task: '${task.id}', ok: true}, or ok: false with the error.`
diff --git a/core/src/shared/text-boundary.js b/core/src/shared/text-boundary.js
index 903c5595e..f8bb316f4 100644
--- a/core/src/shared/text-boundary.js
+++ b/core/src/shared/text-boundary.js
@@ -23,6 +23,11 @@ export const fits = (text, max) => {
 }
 
 // A bounded prefix that never splits a surrogate pair. `cut` says whether anything was dropped.
+// `max` stays a UTF-16 unit budget, on purpose: its callers bound the units a stored field may cost
+// (a capability description at 2000, the open-page snapshot's address and title, a busy-ack prompt
+// at 600), and those shapes are pinned by tests. `fits` above is the *character* judgment, for a
+// consumer whose budget is characters (#2321); the two questions differ on purpose, and what must
+// never differ is that the kept prefix ends on a code point boundary (#1963, #2581).
 // The input is flattened first (#1963): a string that already carried an unpaired surrogate went
 // straight through, so the caller stored a value that was not well formed. U+FFFD is one UTF-16 unit
 // for the one it replaces, so a well-formed input keeps its exact prefix and its `cut` flag.
diff --git a/core/test/task-drive.test.js b/core/test/task-drive.test.js
index 690d6eda9..5bca7ce3d 100644
--- a/core/test/task-drive.test.js
+++ b/core/test/task-drive.test.js
@@ -636,3 +636,18 @@ test('the reminder cap never silences the task own work (#1172)', async (t) => {
   assert.equal(app.calls('s').length, 2, 'a working task wakes even with the comment reminder used up')
   assert.match(app.calls('s')[1].content.map(block => block.text).join('\n'), new RegExp(`Continue ${id} \\[normal\\] Ship the fix`))
 })
+
+// #2581: the cue re-cuts the title that tasks.js already bounded, and the second bound must land on
+// a code point boundary. A title of emoji is two UTF-16 units per character, so the old 200-unit
+// slice ended inside one and the other Bot's turn read a lone surrogate as U+FFFD.
+test('#2581: a title of emoji is cut on a code point boundary in the cue', async (t) => {
+  const app = await start(t)
+  // Five ASCII units plus 300 emoji units: the 200-unit offset lands inside a face.
+  const title = `Draft${'🚀'.repeat(150)}`
+  const body = await app.track('s', { tasks: [{ title, column: 'not-started' }] })
+  const id = app.idOf(body, 'Draft')
+  const cue = app.calls('s').at(-1).content.map(block => block.text ?? '').join('\n')
+  assert.equal(cue.isWellFormed(), true, 'the cue carries no lone surrogate')
+  assert.equal(cue.includes('\uFFFD'), false, 'the cue carries no replacement character')
+  assert.match(cue, new RegExp(`Continue ${id} \\[normal\\] Draft`))
+})
diff --git a/patches/ds-bot/files/src/host/task-drive.js b/patches/ds-bot/files/src/host/task-drive.js
index b40bc8555..cc79c21ae 100644
--- a/patches/ds-bot/files/src/host/task-drive.js
+++ b/patches/ds-bot/files/src/host/task-drive.js
@@ -5,6 +5,7 @@
 // open a group Session and does not post the reply into the room. Assigning,
 // progress, and the next assignee are board writes; chat is not the scheduler.
 import { compareForQueue, compareForWork, occupiesSlot, sameRole } from '../shared/task-board.js'
+import { cut } from '../shared/text-boundary.js'
 import { formatRoomBoard } from './room-context.js'
 import { retiredBot } from './store.js'
 
@@ -34,7 +35,7 @@ const fingerprint = (tasks) => tasks.map(task => [
 // A queue item is offered, not owned: this cue names the item and the claim, never its note —
 // the note is the body, and reading it is the turn's job, not the wake's (#1247).
 const queueCueFor = (task) => {
-  const title = String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim().slice(0, 200)
+  const title = cut(String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim(), 200).text
   const priority = task.priority ?? 'normal'
   return `Take ${task.id} [${priority}] ${title} — queued for ${task.queueRole}. Claim it with track_tasks {claim: true, id: '${task.id}'}, then set its column to in-progress. Do not post a status in the group. Stop when it is done or waiting on an answer. Do not invent other work.`
 }
@@ -51,7 +52,7 @@ const queueFingerprint = (task) => (task === undefined ? '' : [
 ].join('\u0000'))
 
 const cueFor = (task) => {
-  const title = String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim().slice(0, 200)
+  const title = cut(String(task.title ?? '').replace(/[\r\n]+/g, ' ').trim(), 200).text
   const priority = task.priority ?? 'normal'
   const post = task.writeBack?.state === 'pending'
     ? ` Then post the decision comment on ${task.writeBack.target} with your GitHub connector and record it with track_tasks postResult {task: '${task.id}', ok: true}, or ok: false with the error.`
diff --git a/patches/ds-bot/files/src/shared/text-boundary.js b/patches/ds-bot/files/src/shared/text-boundary.js
index 903c5595e..f8bb316f4 100644
--- a/patches/ds-bot/files/src/shared/text-boundary.js
+++ b/patches/ds-bot/files/src/shared/text-boundary.js
@@ -23,6 +23,11 @@ export const fits = (text, max) => {
 }
 
 // A bounded prefix that never splits a surrogate pair. `cut` says whether anything was dropped.
+// `max` stays a UTF-16 unit budget, on purpose: its callers bound the units a stored field may cost
+// (a capability description at 2000, the open-page snapshot's address and title, a busy-ack prompt
+// at 600), and those shapes are pinned by tests. `fits` above is the *character* judgment, for a
+// consumer whose budget is characters (#2321); the two questions differ on purpose, and what must
+// never differ is that the kept prefix ends on a code point boundary (#1963, #2581).
 // The input is flattened first (#1963): a string that already carried an unpaired surrogate went
 // straight through, so the caller stored a value that was not well formed. U+FFFD is one UTF-16 unit
 // for the one it replaces, so a well-formed input keeps its exact prefix and its `cut` flag.
diff --git a/patches/ds-bot/files/test/task-drive.test.js b/patches/ds-bot/files/test/task-drive.test.js
index 690d6eda9..5bca7ce3d 100644
--- a/patches/ds-bot/files/test/task-drive.test.js
+++ b/patches/ds-bot/files/test/task-drive.test.js
@@ -636,3 +636,18 @@ test('the reminder cap never silences the task own work (#1172)', async (t) => {
   assert.equal(app.calls('s').length, 2, 'a working task wakes even with the comment reminder used up')
   assert.match(app.calls('s')[1].content.map(block => block.text).join('\n'), new RegExp(`Continue ${id} \\[normal\\] Ship the fix`))
 })
+
+// #2581: the cue re-cuts the title that tasks.js already bounded, and the second bound must land on
+// a code point boundary. A title of emoji is two UTF-16 units per character, so the old 200-unit
+// slice ended inside one and the other Bot's turn read a lone surrogate as U+FFFD.
+test('#2581: a title of emoji is cut on a code point boundary in the cue', async (t) => {
+  const app = await start(t)
+  // Five ASCII units plus 300 emoji units: the 200-unit offset lands inside a face.
+  const title = `Draft${'🚀'.repeat(150)}`
+  const body = await app.track('s', { tasks: [{ title, column: 'not-started' }] })
+  const id = app.idOf(body, 'Draft')
+  const cue = app.calls('s').at(-1).content.map(block => block.text ?? '').join('\n')
+  assert.equal(cue.isWellFormed(), true, 'the cue carries no lone surrogate')
+  assert.equal(cue.includes('\uFFFD'), false, 'the cue carries no replacement character')
+  assert.match(cue, new RegExp(`Continue ${id} \\[normal\\] Draft`))
+})
diff --git a/plugins/social/src/social.js b/plugins/social/src/social.js
index 95b9859f8..acd5643fb 100644
--- a/plugins/social/src/social.js
+++ b/plugins/social/src/social.js
@@ -101,6 +101,14 @@ export const sizeLabel = (n) => {
   const kb = (n / 1024).toFixed(1)
   return Number(kb) >= 1024 ? `${(n / 1048576).toFixed(1)} MB` : `${kb} KB`
 }
+// Cut on code points, never on UTF-16 units: the share envelope leaves this Bot as JSON and a
+// slice that ends inside a surrogate pair reaches the other home as U+FFFD (#2581).
+export const cutCodePoints = (value, max) => {
+  const text = String(value ?? '').toWellFormed()
+  if (!Number.isFinite(max) || text.length <= max) return text
+  return Array.from(text).slice(0, max).join('')
+}
+
 // Remote strings that reach model-visible text: one line, no brackets or markup, capped.
 export const cleanText = (value, fallback = '') => String(value ?? '').replace(/[\u0000-\u001f\u007f-\u009f\u2028\u2029]/g, ' ').replace(/[[\]"<>`]/g, '').replace(/\s+/g, ' ').trim().slice(0, 60) || fallback
 // Owner-only draft body: keep punctuation the friend will see; strip controls and cap.
@@ -1838,7 +1846,7 @@ export function createSocial(service, config = {}, { client: given, api: givenAp
       who: cleanText(flybot.bot.get(msg.from)?.name, 'member'),
       kind: 'message',
       authorKind: 'human',
-      text: String(msg.text ?? '').slice(0, 18_000),
+      text: cutCodePoints(msg.text, 18_000),
       calls: [to],
     }
     return `FLYBOT-ROOM-SHARE\n${JSON.stringify(body)}`
diff --git a/plugins/social/test/social.test.js b/plugins/social/test/social.test.js
index a53b86015..dee488b36 100644
--- a/plugins/social/test/social.test.js
+++ b/plugins/social/test/social.test.js
@@ -1336,6 +1336,41 @@ test('#1141: a co-member reaches a shared-room Bot without being the friendship
   assert.equal((room.participants ?? []).some(p => p.handle === '@coder.bob.home' && p.leftSeq === undefined), false)
 })
 
+// #2581: the co-seat envelope leaves this Bot as JSON, and its 18 000 is a character budget.
+// A UTF-16 slice there can end inside an emoji, and the other home reads half a pair as U+FFFD.
+test('#2581: a co-seat room line keeps its emoji whole at the envelope bound', async (t) => {
+  const rooms = {
+    delivery: {
+      id: 'delivery', name: '交付组', members: ['a', 'b'], admin: 'a', named: true, log: [], seq: 0, seen: {},
+      participants: [
+        { kind: 'bot', id: 'a', role: 'admin', displayName: 'Chief', joinedSeq: 0, joinedAt: 1 },
+        { kind: 'bot', id: 'b', role: 'member', displayName: 'Writer', joinedSeq: 0, joinedAt: 1 },
+        { kind: 'bot', remote: true, id: '@coder.bob.home', handle: '@coder.bob.home', ownerHome: '@bob.home', ownerName: 'Bob', displayName: 'Coder', role: 'member', joinedSeq: 1, joinedAt: 1 },
+      ],
+    },
+  }
+  const { ctx, stop } = await team({ rooms })
+  t.after(stop)
+  const server = mockServer()
+  server.tools.list_remote_bots = () => ({ homes: [{ relationship_id: 'r1', home: { bot_id: 'h2', handle: '@bob.home', display_name: 'Bob', owner_display_name: 'Bob' }, bots: [{ bot_id: 'x1', handle: '@coder.bob.home', display_name: 'Coder' }], scope: 'member', via: ['@writer.danyang.home'] }] })
+  const social = createSocial(ctx.flybot, { autoAccept: true, inboxPollMs: 0 }, { client: createMcpClient({ server: 'https://s', token: 'owner-token', fetch: server.fetch }), home: { id: 'h1', handle: '@danyang.home' } })
+  t.after(() => social.dispose())
+  await grantTeam(ctx.flybot, '@bob.home')
+  await social.registerAll()
+  await social.remoteBots({ fresh: true })
+  await ctx.flybot.grants.set('a', [{ grantee: '@bob.home' }])
+  // 18 001 characters, 36 001 UTF-16 units: the old 18 000-unit slice kept 8 999 faces and half of the next.
+  const text = `A${'🚀'.repeat(18_000)}`
+  const sent = await ctx.flybot.bot.send({ from: 'a', to: '@coder.bob.home', text, role: 'reply', via: 'auto-reply' })
+  assert.equal(sent.action, 'allow', JSON.stringify(sent))
+  const call = server.calls.filter(item => item.name === 'send_as_member').at(-1)
+  const body = JSON.parse(String(call.args.text).slice('FLYBOT-ROOM-SHARE\n'.length))
+  assert.equal(body.text.isWellFormed(), true, 'the envelope text carries no lone surrogate')
+  assert.equal(body.text.includes('\uFFFD'), false)
+  assert.equal(Array.from(body.text).length, 18_000, 'the budget is characters, the shared text included')
+  assert.equal(body.text, `A${'🚀'.repeat(17_999)}`)
+})
+
 // A server that holds every send_as_member and lists the holds. `reasons` names what Bot Social
 // held it for: the plain approval requirement, or a finding of its own (a DLP category).
 function holdingServer({ reasons = ['mvp.all_outbound_requires_approval'], riskFlags = [], holdReason } = {}) {
diff --git a/plugins/timeline/src/sanitize.js b/plugins/timeline/src/sanitize.js
index a55ff967f..3cb6fa73c 100644
--- a/plugins/timeline/src/sanitize.js
+++ b/plugins/timeline/src/sanitize.js
@@ -5,11 +5,21 @@ const CONTROLS = /[\u0000-\u001f\u007f-\u009f\u2028\u2029]/g
 // Bidirectional overrides and isolates reorder text on screen; zero-width characters hide it.
 const INVISIBLE = /[\u200b-\u200f\u202a-\u202e\u2060-\u2064\u2066-\u2069\ufeff]/g
 
+// Cut on code points, never on UTF-16 units: `max` is a character budget and a unit offset can
+// end inside a surrogate pair, so the panel or the exported JSON would carry half a character
+// (#2581). The input is flattened first, so a value that already carried an unpaired surrogate is
+// never stored as one.
+const cutCodePoints = (text, max) => {
+  const value = text.toWellFormed()
+  if (!Number.isFinite(max) || value.length <= max) return value
+  return Array.from(value).slice(0, max).join('')
+}
+
 // One line of plain text, no controls, no fence markers, no angle brackets, capped.
 export const cleanLabel = (value, max = 60) => {
   let out = String(value ?? '').replace(CONTROLS, ' ').replace(INVISIBLE, '')
   for (let previous; previous !== out;) { previous = out; out = out.replace(/<\s*\/?\s*untrusted-?/gi, '') }
-  return out.replace(/[<>`"]/g, '').replace(/\s+/g, ' ').trim().slice(0, max)
+  return cutCodePoints(out.replace(/[<>`"]/g, '').replace(/\s+/g, ' ').trim(), max)
 }
 
 const ID = /^[A-Za-z0-9][A-Za-z0-9:_#.@-]{0,159}$/
diff --git a/plugins/timeline/test/sanitize.test.js b/plugins/timeline/test/sanitize.test.js
index 7a8ec60b1..3fdfa057a 100644
--- a/plugins/timeline/test/sanitize.test.js
+++ b/plugins/timeline/test/sanitize.test.js
@@ -54,3 +54,16 @@ test('cleanCode keeps an enumerated error code and nothing else', () => {
   assert.equal(cleanCode('AUTH'), 'AUTH')
   for (const bad of ['sk-live-0123456789abcdef', 'quota exceeded for key abc', 'rate_limit', '<b>', '', 'A'.repeat(41), 5, null, undefined]) assert.equal(cleanCode(bad), 'UNKNOWN', String(bad))
 })
+
+// #2581: 60 is a character budget. A label of emoji is 120 UTF-16 units, and a unit slice at 60
+// ends inside the 31st face, so the panel and the exported JSON carried half a character.
+test('#2581: cleanLabel cuts emoji on a code point boundary', () => {
+  const out = cleanLabel('🚀'.repeat(61))
+  assert.equal(out.isWellFormed(), true)
+  assert.equal(out.includes('\uFFFD'), false)
+  assert.equal(Array.from(out).length, 60)
+  assert.equal(out, '🚀'.repeat(60))
+  // A label already inside the budget is untouched, however many units it costs.
+  const short = '🚀'.repeat(30)
+  assert.equal(cleanLabel(short), short)
+})
diff --git a/plugins/workflow/client.js b/plugins/workflow/client.js
index dde5b571e..8f825b446 100644
--- a/plugins/workflow/client.js
+++ b/plugins/workflow/client.js
@@ -295,6 +295,14 @@ window.__ModuleLoader__.load({
     const COLUMN_KEY = { 'not-started': 'Not started', 'in-progress': 'In progress', done: 'Done' }
     const COLUMN_OF = { open: 'not-started', claimed: 'not-started', working: 'in-progress', blocked: 'in-progress', 'result-ready': 'in-progress', accepted: 'done', cancelled: 'done', failed: 'done' }
     const COLORS = { Planner: '#8b5cf6', Writer: '#f0509a', Coder: '#1fbf6a', Reviewer: '#f5a524', Tester: '#14b8a6', Deployer: '#2f7cf6', '研究员': '#a78bfa', '数据分析师': '#ec4899' }
+    // One code point, not one UTF-16 unit: half a surrogate pair renders as a replacement
+    // character in the avatar circle (#2017, #2581).
+    const firstGlyph = name => Array.from(String(name ?? '').trim())[0] ?? '?'
+    // A cut in code points, so a label never ends inside a surrogate pair (#2581).
+    const cutCodePoints = (value, max) => {
+      const text = String(value ?? '')
+      return text.length <= max ? text : Array.from(text).slice(0, max).join('')
+    }
     // Zero-width plane center line: shift wire coordinates so strokes stay inside the SVG box.
     const WIRE_SPAN = 480
     const NODE_WIRE_OUT = 56
@@ -397,7 +405,7 @@ window.__ModuleLoader__.load({
       const Avatar = globalThis.__flybot__?.BotAvatar
       if (bot && typeof Avatar === 'function') return h(Avatar, { bot, size, badge: false, live: false })
       const color = COLORS[node?.name] ?? '#4d6bfe'
-      return h('span', { className: 'wf-av', style: { background: color, width: size, height: size, fontSize: Math.max(11, size * 0.42) } }, (node?.name ?? '?').slice(0, 1))
+      return h('span', { className: 'wf-av', style: { background: color, width: size, height: size, fontSize: Math.max(11, size * 0.42) } }, firstGlyph(node?.name))
     }
 
     const BOT_TINTS = ['#4d6bfe', '#8b5cf6', '#14b8a6', '#f5a524', '#ec4899', '#1fbf6a', '#2f7cf6']
@@ -410,7 +418,7 @@ window.__ModuleLoader__.load({
     function botPaletteSubtitle(bot, peers) {
       const role = String(bot?.role ?? '').replace(/\s+/g, ' ').trim()
       const dupes = (peers ?? []).filter(item => item.name === bot.name).length > 1
-      if (role) return role.length > 28 ? `${role.slice(0, 27)}…` : role
+      if (role) return Array.from(role).length > 28 ? `${cutCodePoints(role, 27)}…` : role
       if (dupes && bot?.id) return `…${String(bot.id).slice(-6)}`
       return ''
     }
@@ -422,7 +430,7 @@ window.__ModuleLoader__.load({
       return h('span', {
         className: 'wf-palette-av',
         style: { background: color, width: size, height: size, fontSize: Math.max(11, size * 0.42) },
-      }, (bot?.name ?? '?').slice(0, 1))
+      }, firstGlyph(bot?.name))
     }
 
     function PaletteBotChip({ bot, peers, onPointerDown, dragging }) {
@@ -515,7 +523,7 @@ window.__ModuleLoader__.load({
               fill: color,
               fontSize: 12,
               fontWeight: 600,
-            }, (node.name ?? '?').slice(0, 1)))
+            }, firstGlyph(node.name)))
         })))
     }
 
@@ -2690,7 +2698,7 @@ window.__ModuleLoader__.load({
       runHistoryRows, liveStageRuns, resolveFocusedRun, newestAttempt, parallelFrameStyle, fitPlane,
       editPlane, flowLayout, flowRows,
       DRAWER_FLOW_W, NODE_W, NODE_H,
-      botPaletteSubtitle, botTint, settledCall,
+      botPaletteSubtitle, botTint, settledCall, firstGlyph, MiniFlowchart,
     }
   },
 })
diff --git a/plugins/workflow/src/graph.js b/plugins/workflow/src/graph.js
index 582ef67d4..fc48875c4 100644
--- a/plugins/workflow/src/graph.js
+++ b/plugins/workflow/src/graph.js
@@ -18,6 +18,16 @@ function stripControls(value) {
   return out
 }
 
+// Cut on code points, never on UTF-16 units: a unit offset can split a surrogate
+// pair and leave a lone surrogate, which renders as a replacement character. `max` is a
+// code-point budget (the rule of core's shared/text-boundary.js), and the input is flattened
+// first so a value that already carried an unpaired surrogate is never stored as one.
+export function cutCodePoints(value, max) {
+  const text = String(value ?? '').toWellFormed()
+  if (!Number.isFinite(max) || text.length <= max) return text
+  return Array.from(text).slice(0, max).join('')
+}
+
 // Cut on code points, never on UTF-16 units: a unit offset can split a surrogate
 // pair and leave a lone surrogate, which renders as a replacement character.
 export function cleanLine(value, max = 300) {
diff --git a/plugins/workflow/src/service.js b/plugins/workflow/src/service.js
index 6ff241c75..a3353df16 100644
--- a/plugins/workflow/src/service.js
+++ b/plugins/workflow/src/service.js
@@ -7,7 +7,7 @@ import { lstatSync, mkdirSync, readFileSync, renameSync, writeFileSync } from 'n
 import { join } from 'node:path'
 import { releaseAll, spawnAll } from './ephemeral.js'
 import {
-  chainLabel, cleanLine, cleanPorts, cleanPrompt, cleanTools, completeNode, doneCount, failNode, freshStatus, layerMarks,
+  chainLabel, cleanLine, cleanPorts, cleanPrompt, cleanTools, completeNode, cutCodePoints, doneCount, failNode, freshStatus, layerMarks,
   missingProviders, missingVerdicts, nodeById, normalizeGraph, orderedIds, readStepResult, resolveInputs, retryNode,
   rowPreview, startFrontier, summarizeTask, unmetRequired, validateGraph,
 } from './graph.js'
@@ -21,6 +21,11 @@ const MAX_MESSAGES = 200
 const FILE = 'workflows.json'
 const DEFAULT_CONCURRENT = 2
 const MAX_CONCURRENT = 8
+// #2581: a failed step's own text is the node's (or peer Bot's) output, so the bound goes through
+// cutCodePoints: a UTF-16 slice at 197 units can end inside an emoji and every reader downstream
+// gets U+FFFD. 200 is the budget in characters, the ellipsis included.
+const clipFailureText = text => (Array.from(text).length > 200 ? `${cutCodePoints(text, 197)}…` : text)
+
 const MAX_ORPHANS = 50
 // How many held task ids a workflow lists in `workflow/state`; the count beside
 // them is always the whole truth (#1647).
@@ -635,7 +640,7 @@ export function createWorkflowService({
         code: 'step-failed',
         at: next.updatedAt,
         ...(node ? { nodeName: node.name } : {}),
-        ...(text ? { text: text.length > 200 ? `${text.slice(0, 197)}…` : text } : {}),
+        ...(text ? { text: clipFailureText(text) } : {}),
       }
     }
     const lines = linesFor(item, working.task, {
diff --git a/plugins/workflow/test/client.test.js b/plugins/workflow/test/client.test.js
index 5664b3573..664df980e 100644
--- a/plugins/workflow/test/client.test.js
+++ b/plugins/workflow/test/client.test.js
@@ -4854,3 +4854,44 @@ test('a paused run is named Paused in the strip and in the Runs history', async
     view.unmount()
   }
 })
+
+// #2581: an avatar takes one code point, not one UTF-16 unit; the role line and the canvas label
+// are bounded in characters for the same reason. A name or role of emoji used to leave half a
+// surrogate pair in the circle / subtitle / flowchart.
+test('#2581: an emoji-leading name keeps one whole character in the palette avatar', async () => {
+  const graph = delivery()
+  const call = async (name) => (name === 'workflow/state' ? { workflows: [graph], templates: [] } : { ok: true, workflows: [graph] })
+  const roster = { bots: [{ id: 'chief-e', name: '🚀Dev', role: 'Ops', remote: false }] }
+  const view = mount(client.Section, { roster, call, actions: {} })
+  try {
+    await settle()
+    findAll(view.tree, node => node.type === 'button' && textOf(node).includes('发布交付流水线'))[0].props.onClick()
+    button(view.tree, 'Flow').props.onClick()
+    button(view.tree, 'Edit').props.onClick()
+    await settle()
+    const avatar = findAll(view.tree, node => node.props?.className === 'wf-palette-av')[0]
+    assert.ok(avatar, 'the palette renders the Bot avatar')
+    assert.equal(textOf(avatar), '🚀')
+    assert.equal(client.firstGlyph('🚀Dev'), '🚀')
+    assert.equal(client.firstGlyph(''), '?')
+  } finally {
+    view.unmount()
+  }
+  const role = client.botPaletteSubtitle({ id: 'chief-e', name: '🚀Dev', role: '🚀'.repeat(28) }, roster.bots)
+  assert.equal(role.isWellFormed(), true, 'the subtitle carries no lone surrogate')
+  assert.equal(role.includes('\uFFFD'), false)
+  assert.equal(Array.from(role).length, 28, '27 characters plus the ellipsis')
+})
+
+test('#2581: the canvas node label is one code point', () => {
+  const graph = delivery()
+  graph.nodes = graph.nodes.map(node => (node.id === 'coder' ? { ...node, name: '🚀Dev' } : node))
+  const view = mount(client.MiniFlowchart, { workflow: graph })
+  try {
+    const labels = findAll(view.tree, node => node.type === 'text').map(textOf)
+    assert.ok(labels.includes('🚀'), `the flowchart text labels are ${JSON.stringify(labels)}`)
+    assert.equal(labels.every(label => label.isWellFormed()), true, 'no label is half a pair')
+  } finally {
+    view.unmount()
+  }
+})
diff --git a/plugins/workflow/test/code-point-cut.test.js b/plugins/workflow/test/code-point-cut.test.js
new file mode 100644
index 000000000..bf6ffa5ec
--- /dev/null
+++ b/plugins/workflow/test/code-point-cut.test.js
@@ -0,0 +1,28 @@
+// #2581: every bound in this plugin judges characters, not UTF-16 units. A failed step's own text
+// is the node's or the peer Bot's output, so a unit slice at 197 ends inside an emoji and the
+// stored failure, the history and the API all carry a lone surrogate (U+FFFD once encoded).
+import assert from 'node:assert/strict'
+import { test } from 'node:test'
+import { createWorkflowService } from '../src/service.js'
+
+const NOW = 1_700_000_000_000
+
+test('#2581: a failed step keeps a well-formed text when its characters are emoji', async () => {
+  const svc = createWorkflowService({ persist: false, now: () => NOW, bots: () => [] })
+  const made = svc.define({
+    name: 'Lane',
+    nodes: [{ id: 'plan', name: 'Planner', prompt: 'Write the plan.' }],
+    edges: [],
+  })
+  const id = made.workflows.find(item => item.name === 'Lane').id
+  const started = await svc.runNamed({ workflow: 'Lane', brief: 'go' })
+  const runId = started.workflows.find(item => item.id === id).run.id
+  // 300 characters, 600 units: the old 197-unit slice kept 98 faces and half of the 99th.
+  const text = '🚀'.repeat(300)
+  const failed = svc.advance({ workflowId: id, runId, nodeId: 'plan', outcome: 'failed', text })
+  const failure = failed.workflows.find(item => item.id === id).run.failure
+  assert.equal(failure.text.isWellFormed(), true, 'the stored failure text is well formed')
+  assert.equal(failure.text.includes('\uFFFD'), false)
+  assert.equal(failure.text.endsWith('🚀…'), true)
+  assert.equal(Array.from(failure.text).length, 198, '197 characters plus the ellipsis')
+})
diff --git a/plugins/workflow/test/graph.test.js b/plugins/workflow/test/graph.test.js
index 69cb7ff6e..9bb626315 100644
--- a/plugins/workflow/test/graph.test.js
+++ b/plugins/workflow/test/graph.test.js
@@ -1,7 +1,7 @@
 import assert from 'node:assert/strict'
 import { test } from 'node:test'
 import {
-  addNode, chainLabel, cleanLine, cleanPrompt, completeNode, connectNodes, doneCount, failNode, freshStatus, layerMarks,
+  addNode, chainLabel, cleanLine, cleanPrompt, completeNode, connectNodes, cutCodePoints, doneCount, failNode, freshStatus, layerMarks,
   moveNode, nextDemoOp, normalizeGraph, readStepResult, reconnectEdge, removeEdge, removeNode, retryNode,
   rowPreview, startFrontier, summarizeTask, validateGraph,
 } from '../src/graph.js'
@@ -209,3 +209,14 @@ test('a node prompt and a step reply stop on the bound without splitting the cha
   assert.equal(step.text, reply, 'the step body keeps the whole last character')
   assert.equal(hasLoneSurrogate(step.text), false, 'readStepResult left a lone surrogate in the body')
 })
+
+// #2581: the plugin's own bound judges characters, not UTF-16 units.
+test('#2581: cutCodePoints counts characters, not UTF-16 units', () => {
+  assert.equal(cutCodePoints('🚀Dev', 1), '🚀')
+  assert.equal(cutCodePoints('🚀Dev', 10), '🚀Dev')
+  assert.equal(cutCodePoints('🚀'.repeat(3), 2), '🚀🚀')
+  assert.equal(cutCodePoints('🚀'.repeat(3), 2).isWellFormed(), true)
+  // A value that already carried an unpaired surrogate is flattened, never stored as one.
+  assert.equal(cutCodePoints('a\uD800b', 10).isWellFormed(), true)
+  assert.equal(cutCodePoints(undefined, 5), '')
+})