diff --git a/packages/voko-exchange/package.json b/packages/voko-exchange/package.json
index 6198a09..a617072 100644
--- a/packages/voko-exchange/package.json
+++ b/packages/voko-exchange/package.json
@@ -5,5 +5,11 @@
   "type": "module",
   "exports": {
     ".": "./src/index.js"
+  },
+  "scripts": {
+    "test": "vitest run"
+  },
+  "devDependencies": {
+    "vitest": "^2.1.4"
   }
 }
diff --git a/packages/voko-exchange/src/index.js b/packages/voko-exchange/src/index.js
index 99e9309..1feafe4 100644
--- a/packages/voko-exchange/src/index.js
+++ b/packages/voko-exchange/src/index.js
@@ -1,9 +1,11 @@
 /**
  * `@voko/exchange` —— VOKO 的任务交换：公会、Agent、任务、检查点、提交、验收、评论、求助、事件与定时任务。
  *
- * 当前只有表结构；状态机与 service 在 W1–W3 加入。
+ * 当前有表结构、任务构造点与状态机纯函数；service 在 W2–W3 加入。
  *
  * 边界：不读 `process.env`、不建连接；db 由 composition root 注入。
  */
 
+export { taskFromRow, TASK_STATUSES, TASK_TEMPLATES } from './task.js'
+export { transition, publishStatus, TASK_ACTIONS, MAX_ACTIVE_HOLDS } from './transition.js'
 export { default as exchangeDbSchema } from './db/tables/index.cjs'
diff --git a/packages/voko-exchange/src/task.js b/packages/voko-exchange/src/task.js
new file mode 100644
index 0000000..624248d
--- /dev/null
+++ b/packages/voko-exchange/src/task.js
@@ -0,0 +1,175 @@
+/** 任务的全部状态；消费方 switch 必须穷举。与 DB CHECK `ck_vk_tasks_status` 一致。 */
+export const TASK_STATUSES = Object.freeze([
+  'pending_approval',
+  'open',
+  'claimed',
+  'in_contest',
+  'submitted',
+  'reviewing',
+  'rework',
+  'disputed',
+  'settled',
+  'cancelled',
+  'refunded',
+])
+
+export const TASK_TEMPLATES = Object.freeze(['piecework', 'contest'])
+
+/**
+ * @typedef {'pending_approval'|'open'|'claimed'|'in_contest'|'submitted'|'reviewing'|'rework'|'disputed'|'settled'|'cancelled'|'refunded'} TaskStatus
+ *
+ * @typedef {{
+ *   id: string,
+ *   guild_id: string,
+ *   publisher_agent_id: string,
+ *   template: 'piecework'|'contest',
+ *   title: string,
+ *   spec: string,
+ *   reward: number,
+ *   rarity: number,
+ *   deadline_at: Date,
+ *   status: TaskStatus,
+ *   client_request_key: string,
+ *   holder_agent_id: string|null,
+ *   next_checkpoint_due_at: Date|null,
+ *   missed_checkpoints: number,
+ *   rework_count: number,
+ *   review_due_at: Date|null,
+ *   settled_at: Date|null,
+ *   created_at: Date,
+ *   updated_at: Date|null,
+ * }} Task
+ */
+
+/**
+ * DB 行 → Task 的唯一构造点。按状态保证必有字段，非法即 throw；下游读取零判空。
+ * @param {Record<string, any>} row
+ * @returns {Task}
+ */
+export function taskFromRow(row) {
+  const id = requiredString(row.id, 'id', row.id)
+  if (!TASK_TEMPLATES.includes(row.template)) throw new Error(`vk_tasks.template invalid: ${row.template}, id: ${id}`)
+  const holder = row.holder_agent_id === null ? null : requiredString(row.holder_agent_id, 'holder_agent_id', id)
+  const nextCheckpointDue = nullableDate(row.next_checkpoint_due_at, 'next_checkpoint_due_at', id)
+  const reviewDue = nullableDate(row.review_due_at, 'review_due_at', id)
+  const settledAt = nullableDate(row.settled_at, 'settled_at', id)
+
+  switch (row.status) {
+    case 'claimed':
+      requirePiecework(row, id)
+      if (holder === null) throw new Error(`vk_tasks.holder_agent_id missing for claimed, id: ${id}`)
+      if (nextCheckpointDue === null) throw new Error(`vk_tasks.next_checkpoint_due_at missing for claimed, id: ${id}`)
+      break
+    case 'submitted':
+      requirePiecework(row, id)
+      if (holder === null) throw new Error(`vk_tasks.holder_agent_id missing for submitted, id: ${id}`)
+      if (reviewDue === null) throw new Error(`vk_tasks.review_due_at missing for submitted, id: ${id}`)
+      break
+    case 'rework':
+      requirePiecework(row, id)
+      if (holder === null) throw new Error(`vk_tasks.holder_agent_id missing for rework, id: ${id}`)
+      break
+    case 'in_contest':
+      requireContest(row, id)
+      break
+    case 'reviewing':
+      requireContest(row, id)
+      if (reviewDue === null) throw new Error(`vk_tasks.review_due_at missing for reviewing, id: ${id}`)
+      break
+    case 'settled':
+      if (settledAt === null) throw new Error(`vk_tasks.settled_at missing for settled, id: ${id}`)
+      break
+    case 'pending_approval':
+    case 'open':
+    case 'disputed':
+    case 'cancelled':
+    case 'refunded':
+      break
+    default:
+      throw new Error(`Unhandled status: ${row.status}, id: ${id}`)
+  }
+  if (row.template === 'contest' && holder !== null) throw new Error(`vk_tasks contest has holder, id: ${id}`)
+
+  return {
+    id,
+    guild_id: requiredString(row.guild_id, 'guild_id', id),
+    publisher_agent_id: requiredString(row.publisher_agent_id, 'publisher_agent_id', id),
+    template: row.template,
+    title: requiredString(row.title, 'title', id),
+    spec: requiredString(row.spec, 'spec', id),
+    reward: integerInRange(row.reward, 1, Number.MAX_SAFE_INTEGER, 'reward', id),
+    rarity: integerInRange(row.rarity, 1, 10, 'rarity', id),
+    deadline_at: requiredDate(row.deadline_at, 'deadline_at', id),
+    status: row.status,
+    client_request_key: requiredString(row.client_request_key, 'client_request_key', id),
+    holder_agent_id: holder,
+    next_checkpoint_due_at: nextCheckpointDue,
+    missed_checkpoints: integerInRange(row.missed_checkpoints, 0, 1, 'missed_checkpoints', id),
+    rework_count: integerInRange(row.rework_count, 0, 2, 'rework_count', id),
+    review_due_at: reviewDue,
+    settled_at: settledAt,
+    created_at: requiredDate(row.created_at, 'created_at', id),
+    updated_at: nullableDate(row.updated_at, 'updated_at', id),
+  }
+}
+
+/**
+ * @param {Record<string, any>} row
+ * @param {string} id
+ */
+function requirePiecework(row, id) {
+  if (row.template !== 'piecework') throw new Error(`vk_tasks status ${row.status} requires piecework, id: ${id}`)
+}
+
+/**
+ * @param {Record<string, any>} row
+ * @param {string} id
+ */
+function requireContest(row, id) {
+  if (row.template !== 'contest') throw new Error(`vk_tasks status ${row.status} requires contest, id: ${id}`)
+}
+
+/**
+ * @param {unknown} value
+ * @param {string} field
+ * @param {unknown} id
+ * @returns {string}
+ */
+function requiredString(value, field, id) {
+  if (typeof value === 'string' && value.length > 0) return value
+  throw new Error(`vk_tasks.${field} invalid, id: ${String(id)}`)
+}
+
+/**
+ * @param {unknown} value
+ * @param {string} field
+ * @param {string} id
+ * @returns {Date}
+ */
+function requiredDate(value, field, id) {
+  if (value instanceof Date) return value
+  throw new Error(`vk_tasks.${field} invalid, id: ${id}`)
+}
+
+/**
+ * @param {unknown} value
+ * @param {string} field
+ * @param {string} id
+ * @returns {Date|null}
+ */
+function nullableDate(value, field, id) {
+  return value === null ? null : requiredDate(value, field, id)
+}
+
+/**
+ * @param {unknown} value
+ * @param {number} min
+ * @param {number} max
+ * @param {string} field
+ * @param {string} id
+ * @returns {number}
+ */
+function integerInRange(value, min, max, field, id) {
+  if (Number.isSafeInteger(value) && /** @type {number} */ (value) >= min && /** @type {number} */ (value) <= max) return /** @type {number} */ (value)
+  throw new Error(`vk_tasks.${field} invalid: ${String(value)}, id: ${id}`)
+}
diff --git a/packages/voko-exchange/src/transition.js b/packages/voko-exchange/src/transition.js
new file mode 100644
index 0000000..635a5da
--- /dev/null
+++ b/packages/voko-exchange/src/transition.js
@@ -0,0 +1,495 @@
+/**
+ * 任务状态机：平台强制的规则只在这里写一遍。
+ *
+ * `transition()` 是纯函数：只返回新任务与要做的副作用（持有记录、托管动作、事件、job），
+ * 由 service 在锁住任务行的同一个事务里执行。它不读库、不读时钟。
+ *
+ * 不在这里判的规则（需要读其它表，由 service 在同一事务里保证）：
+ * 重复报名（vk_task_entries UNIQUE）、转让请求是否 pending 且指向 actor、验收 checks 与清单的覆盖关系。
+ */
+
+import { TASK_STATUSES } from './task.js'
+
+/** 除发布（新建，见 `publishStatus`）外的全部动作。 */
+export const TASK_ACTIONS = Object.freeze([
+  'approve',
+  'reject_approval',
+  'claim',
+  'enter',
+  'cancel',
+  'open_expire',
+  'edit',
+  'checkpoint',
+  'checkpoint_miss',
+  'release',
+  'hold_timeout',
+  'transfer_accept',
+  'submit',
+  'accept',
+  'reject',
+  'review_auto_accept',
+  'contest_close',
+  'select_winner',
+  'dispute',
+  'resolve',
+])
+
+/** 每个 Agent 同时持有的计件活上限。 */
+export const MAX_ACTIVE_HOLDS = 3
+
+const HOUR_MS = 3600_000
+
+/**
+ * @typedef {import('./task.js').Task} Task
+ *
+ * @typedef {{
+ *   task: Task,
+ *   guild: { checkpoint_interval_sec: number, piece_review_window_sec: number, contest_review_window_sec: number },
+ *   publisher_owner_user_id: string,
+ * }} TaskState 任务行 + 所属公会的时间规则 + 发布方 Agent 的主人，由 service 在事务内读出。
+ *
+ * @typedef {{ kind: 'agent', agent_id: string, owner_user_id: string, max_rarity: number, active_hold_count: number, is_entrant: boolean }} AgentActor
+ * @typedef {AgentActor | { kind: 'lead', user_id: string } | { kind: 'operator', user_id: string } | { kind: 'worker' }} Actor
+ *
+ * @typedef {(
+ *   { type: 'approve' } | { type: 'reject_approval' } | { type: 'claim' } | { type: 'enter' } | { type: 'cancel' } |
+ *   { type: 'open_expire' } | { type: 'edit', add_reward: number, deadline_at: Date|null } | { type: 'checkpoint' } |
+ *   { type: 'checkpoint_miss' } | { type: 'release' } | { type: 'hold_timeout' } | { type: 'transfer_accept' } |
+ *   { type: 'submit' } | { type: 'accept' } | { type: 'reject' } | { type: 'review_auto_accept', winner_agent_id: string|null } |
+ *   { type: 'contest_close' } | { type: 'select_winner', winner_agent_id: string } | { type: 'dispute' } |
+ *   { type: 'resolve', outcome: 'settled'|'refunded', winner_agent_id: string|null }
+ * )} Action
+ *
+ * @typedef {(
+ *   { type: 'hold_start', agent_id: string } |
+ *   { type: 'hold_end', reason: 'submitted'|'released'|'timeout'|'transferred' } |
+ *   { type: 'hold_checkpoint' } |
+ *   { type: 'entry_add', agent_id: string } |
+ *   { type: 'escrow_topup', amount: number } |
+ *   { type: 'escrow_refund' } |
+ *   { type: 'escrow_settle', winner_agent_id: string } |
+ *   { type: 'dispute_open', opened_by_agent_id: string } |
+ *   { type: 'event', event_type: string, target_agent_id: string|null } |
+ *   { type: 'job', kind: string, run_at: Date }
+ * )} Effect `event.target_agent_id` 为 null 表示发给整个公会。
+ *
+ * @typedef {{ ok: true, task: Task, effects: Effect[] } | { ok: false, code: 'state_conflict'|'rule_violation'|'forbidden', hint: string }} TransitionResult
+ */
+
+/**
+ * 发布时的初始状态：公会开启发布前审核且发布方是公司 Agent 时先进待审核。
+ * @param {{ require_lead_approval: boolean, publisher_role: 'company'|'member' }} input
+ * @returns {'open'|'pending_approval'}
+ */
+export function publishStatus({ require_lead_approval, publisher_role }) {
+  switch (publisher_role) {
+    case 'company':
+      return require_lead_approval ? 'pending_approval' : 'open'
+    case 'member':
+      return 'open'
+    default:
+      throw new Error(`Unhandled publisher role: ${publisher_role}`)
+  }
+}
+
+/**
+ * @param {TaskState} state
+ * @param {Action} action
+ * @param {Actor} actor
+ * @param {Date} now
+ * @returns {TransitionResult}
+ */
+export function transition(state, action, actor, now) {
+  const { task } = state
+  if (!TASK_ACTIONS.includes(action.type)) throw new Error(`Unhandled action: ${action.type}, id: ${task.id}`)
+  const handlers = TRANSITIONS[task.status]
+  if (handlers === undefined) throw new Error(`Unhandled status: ${task.status}, id: ${task.id}`)
+  const handler = handlers[action.type]
+  if (handler === undefined) return fail('state_conflict', `Task is ${task.status}; ${action.type} is not allowed. Re-fetch the task.`)
+  return handler(state, /** @type {any} */ (action), actor, now)
+}
+
+/** @typedef {(state: TaskState, action: any, actor: Actor, now: Date) => TransitionResult} Handler */
+
+/** @type {Record<import('./task.js').TaskStatus, Partial<Record<Action['type'], Handler>>>} */
+const TRANSITIONS = {
+  pending_approval: {
+    approve({ task }, _action, actor) {
+      if (actor.kind !== 'lead') return notAllowed('Only the guild lead can approve.')
+      return ok({ ...task, status: 'open' }, [event('task.published', null), ...openJobs(task)])
+    },
+    reject_approval({ task }, _action, actor) {
+      if (actor.kind !== 'lead') return notAllowed('Only the guild lead can reject.')
+      return ok({ ...task, status: 'cancelled' }, [{ type: 'escrow_refund' }])
+    },
+  },
+
+  open: {
+    claim(state, _action, actor, now) {
+      const { task } = state
+      if (task.template !== 'piecework') return fail('rule_violation', 'This task is a contest; use enter.')
+      const refused = takerRefusal(state, actor)
+      if (refused !== null) return refused
+      const taker = /** @type {AgentActor} */ (actor)
+      if (taker.active_hold_count >= MAX_ACTIVE_HOLDS) return fail('state_conflict', `You already hold ${MAX_ACTIVE_HOLDS} piecework tasks.`)
+      return ok(hold(state, taker.agent_id, now), [
+        { type: 'hold_start', agent_id: taker.agent_id },
+        event('task.claimed', task.publisher_agent_id),
+        ...checkpointJobs(state, now),
+        job('hold_timeout', task.deadline_at),
+      ])
+    },
+    enter(state, _action, actor) {
+      const { task } = state
+      if (task.template !== 'contest') return fail('rule_violation', 'This task is piecework; use claim.')
+      const refused = takerRefusal(state, actor)
+      if (refused !== null) return refused
+      return ok({ ...task, status: 'in_contest' }, [{ type: 'entry_add', agent_id: /** @type {AgentActor} */ (actor).agent_id }])
+    },
+    cancel({ task }, _action, actor) {
+      if (!isPublisher(task, actor)) return notAllowed('Only the publisher can cancel.')
+      return ok({ ...task, status: 'cancelled' }, [{ type: 'escrow_refund' }])
+    },
+    open_expire({ task }, _action, actor, now) {
+      if (actor.kind !== 'worker') return notAllowed('Only the platform can expire a task.')
+      if (now < task.deadline_at) return fail('state_conflict', 'Deadline has not passed.')
+      return ok({ ...task, status: 'cancelled' }, [{ type: 'escrow_refund' }])
+    },
+    edit({ task }, action, actor) {
+      if (!isPublisher(task, actor)) return notAllowed('Only the publisher can edit.')
+      if (!Number.isSafeInteger(action.add_reward) || action.add_reward < 0) throw new Error(`edit.add_reward invalid: ${action.add_reward}, id: ${task.id}`)
+      if (action.add_reward === 0 && action.deadline_at === null) return fail('rule_violation', 'Nothing to change: add reward or extend the deadline.')
+      if (action.deadline_at !== null && action.deadline_at <= task.deadline_at) return fail('rule_violation', 'The deadline can only be extended.')
+      const next = { ...task, reward: task.reward + action.add_reward, deadline_at: action.deadline_at === null ? task.deadline_at : action.deadline_at }
+      return ok(next, [
+        ...(action.add_reward === 0 ? [] : [/** @type {Effect} */ ({ type: 'escrow_topup', amount: action.add_reward })]),
+        ...(action.deadline_at === null ? [] : openJobs(next)),
+      ])
+    },
+  },
+
+  claimed: {
+    checkpoint(state, _action, actor, now) {
+      if (!isHolder(state.task, actor)) return notAllowed('Only the current holder can post a checkpoint.')
+      return ok({ ...state.task, next_checkpoint_due_at: checkpointDue(state, now), missed_checkpoints: 0 }, [
+        { type: 'hold_checkpoint' },
+        event('task.checkpoint', null),
+        ...checkpointJobs(state, now),
+      ])
+    },
+    checkpoint_miss(state, _action, actor, now) {
+      const { task } = state
+      if (actor.kind !== 'worker') return notAllowed('Only the platform can record a missed checkpoint.')
+      const due = /** @type {Date} */ (task.next_checkpoint_due_at)
+      if (now < due) return fail('state_conflict', 'Checkpoint is not overdue.')
+      if (task.missed_checkpoints >= 1) return ok(reopen(task), releaseEffects(task, 'timeout'))
+      // 第一次缺失只告警：从原到期时刻顺延一个间隔。
+      return ok({ ...task, next_checkpoint_due_at: checkpointDue(state, due), missed_checkpoints: 1 }, checkpointJobs(state, due))
+    },
+    release({ task }, _action, actor) {
+      if (!isHolder(task, actor)) return notAllowed('Only the current holder can release.')
+      return ok(reopen(task), releaseEffects(task, 'released'))
+    },
+    hold_timeout({ task }, _action, actor, now) {
+      if (actor.kind !== 'worker') return notAllowed('Only the platform can time out a hold.')
+      if (now < task.deadline_at) return fail('state_conflict', 'Deadline has not passed.')
+      return ok(reopen(task), releaseEffects(task, 'timeout'))
+    },
+    transfer_accept(state, _action, actor, now) {
+      const refused = takerRefusal(state, actor)
+      if (refused !== null) return refused
+      const taker = /** @type {AgentActor} */ (actor)
+      if (taker.agent_id === state.task.holder_agent_id) return fail('state_conflict', 'You already hold this task.')
+      if (taker.active_hold_count >= MAX_ACTIVE_HOLDS) return fail('state_conflict', `You already hold ${MAX_ACTIVE_HOLDS} piecework tasks.`)
+      return ok(hold(state, taker.agent_id, now), [
+        { type: 'hold_end', reason: 'transferred' },
+        { type: 'hold_start', agent_id: taker.agent_id },
+        ...checkpointJobs(state, now),
+      ])
+    },
+    submit(state, _action, actor, now) {
+      if (!isHolder(state.task, actor)) return notAllowed('Only the current holder can submit.')
+      return ok(...submitted(state, now, [{ type: 'hold_end', reason: 'submitted' }]))
+    },
+  },
+
+  in_contest: {
+    enter(state, _action, actor) {
+      const refused = takerRefusal(state, actor)
+      if (refused !== null) return refused
+      return ok(state.task, [{ type: 'entry_add', agent_id: /** @type {AgentActor} */ (actor).agent_id }])
+    },
+    submit({ task }, _action, actor) {
+      if (actor.kind !== 'agent' || !actor.is_entrant) return notAllowed('Enter the contest before submitting.')
+      // 提交封存到截止，不通知发布方。
+      return ok(task, [])
+    },
+    contest_close(state, _action, actor, now) {
+      const { task } = state
+      if (actor.kind !== 'worker') return notAllowed('Only the platform can close a contest.')
+      if (now < task.deadline_at) return fail('state_conflict', 'Deadline has not passed.')
+      const reviewDue = new Date(now.getTime() + state.guild.contest_review_window_sec * 1000)
+      return ok({ ...task, status: 'reviewing', review_due_at: reviewDue }, [event('task.submitted', task.publisher_agent_id), ...reviewJobs(reviewDue)])
+    },
+  },
+
+  submitted: {
+    accept({ task }, _action, actor, now) {
+      if (!isPublisher(task, actor)) return notAllowed('Only the publisher can review.')
+      const holder = /** @type {string} */ (task.holder_agent_id)
+      return ok(settle(task, now), [{ type: 'escrow_settle', winner_agent_id: holder }, event('task.accepted', holder)])
+    },
+    review_auto_accept({ task }, _action, actor, now) {
+      if (actor.kind !== 'worker') return notAllowed('Only the platform can auto-accept.')
+      if (now < /** @type {Date} */ (task.review_due_at)) return fail('state_conflict', 'Review window has not expired.')
+      const holder = /** @type {string} */ (task.holder_agent_id)
+      return ok(settle(task, now), [
+        { type: 'escrow_settle', winner_agent_id: holder },
+        event('task.auto_accepted', task.publisher_agent_id),
+        event('task.auto_accepted', holder),
+      ])
+    },
+    reject({ task }, _action, actor, now) {
+      if (!isPublisher(task, actor) || actor.kind !== 'agent') return notAllowed('Only the publisher can review.')
+      const holder = /** @type {string} */ (task.holder_agent_id)
+      // 第 3 次驳回直接进仲裁。
+      if (task.rework_count >= 2) return ok({ ...task, status: 'disputed' }, disputeEffects(actor.agent_id, now))
+      return ok({ ...task, status: 'rework', rework_count: task.rework_count + 1, review_due_at: null }, [event('task.rejected', holder)])
+    },
+    dispute: openDispute,
+  },
+
+  reviewing: {
+    select_winner({ task }, action, actor, now) {
+      if (!isPublisher(task, actor)) return notAllowed('Only the publisher can select a winner.')
+      return ok(settle(task, now), [{ type: 'escrow_settle', winner_agent_id: action.winner_agent_id }, event('task.accepted', action.winner_agent_id)])
+    },
+    review_auto_accept({ task }, action, actor, now) {
+      if (actor.kind !== 'worker') return notAllowed('Only the platform can auto-accept.')
+      if (now < /** @type {Date} */ (task.review_due_at)) return fail('state_conflict', 'Review window has not expired.')
+      // 没有任何提交全部通过清单：退款。
+      if (action.winner_agent_id === null) return ok({ ...task, status: 'refunded' }, [{ type: 'escrow_refund' }, event('task.auto_accepted', task.publisher_agent_id)])
+      return ok(settle(task, now), [
+        { type: 'escrow_settle', winner_agent_id: action.winner_agent_id },
+        event('task.auto_accepted', task.publisher_agent_id),
+        event('task.auto_accepted', action.winner_agent_id),
+      ])
+    },
+    dispute: openDispute,
+  },
+
+  rework: {
+    submit(state, _action, actor, now) {
+      if (!isHolder(state.task, actor)) return notAllowed('Only the current holder can submit.')
+      return ok(...submitted(state, now, []))
+    },
+    dispute: openDispute,
+  },
+
+  disputed: {
+    resolve({ task }, action, actor, now) {
+      if (actor.kind !== 'operator') return notAllowed('Only platform operators can resolve a dispute.')
+      const notify = [event('dispute.resolved', task.publisher_agent_id), ...(task.holder_agent_id === null ? [] : [event('dispute.resolved', task.holder_agent_id)])]
+      switch (action.outcome) {
+        case 'settled':
+          if (action.winner_agent_id === null) throw new Error(`resolve.winner_agent_id missing for settled, id: ${task.id}`)
+          return ok(settle(task, now), [{ type: 'escrow_settle', winner_agent_id: action.winner_agent_id }, ...notify])
+        case 'refunded':
+          return ok({ ...task, status: 'refunded' }, [{ type: 'escrow_refund' }, ...notify])
+        default:
+          throw new Error(`Unhandled outcome: ${action.outcome}, id: ${task.id}`)
+      }
+    },
+  },
+
+  settled: {},
+  cancelled: {},
+  refunded: {},
+}
+
+if (Object.keys(TRANSITIONS).length !== TASK_STATUSES.length) throw new Error('TRANSITIONS must cover every task status')
+
+/** @type {Handler} */
+function openDispute({ task }, _action, actor, now) {
+  if (actor.kind !== 'agent') return notAllowed('Only the publisher or a taker can open a dispute.')
+  const isParty = actor.agent_id === task.publisher_agent_id || actor.agent_id === task.holder_agent_id || actor.is_entrant
+  if (!isParty) return notAllowed('Only the publisher or a taker can open a dispute.')
+  return ok({ ...task, status: 'disputed' }, disputeEffects(actor.agent_id, now))
+}
+
+/**
+ * 接单方通用校验：必须是 Agent、不能接自己或同主人 Agent 的任务、稀有度不超过等级上限。
+ * @param {TaskState} state
+ * @param {Actor} actor
+ * @returns {TransitionResult|null}
+ */
+function takerRefusal({ task, publisher_owner_user_id }, actor) {
+  if (actor.kind !== 'agent') return notAllowed('Only agents can take tasks.')
+  if (actor.agent_id === task.publisher_agent_id || actor.owner_user_id === publisher_owner_user_id) {
+    return fail('state_conflict', 'You cannot take a task published by you or by another agent of your owner.')
+  }
+  if (task.rarity > actor.max_rarity) return fail('rule_violation', `Task rarity ${task.rarity} is above your level cap ${actor.max_rarity}.`)
+  return null
+}
+
+/**
+ * @param {Task} task
+ * @param {Actor} actor
+ */
+function isPublisher(task, actor) {
+  return actor.kind === 'agent' && actor.agent_id === task.publisher_agent_id
+}
+
+/**
+ * @param {Task} task
+ * @param {Actor} actor
+ */
+function isHolder(task, actor) {
+  return actor.kind === 'agent' && actor.agent_id === task.holder_agent_id
+}
+
+/**
+ * @param {TaskState} state
+ * @param {Date} from
+ */
+function checkpointDue(state, from) {
+  return new Date(from.getTime() + state.guild.checkpoint_interval_sec * 1000)
+}
+
+/**
+ * @param {TaskState} state
+ * @param {string} agentId
+ * @param {Date} now
+ * @returns {Task}
+ */
+function hold(state, agentId, now) {
+  return { ...state.task, status: 'claimed', holder_agent_id: agentId, next_checkpoint_due_at: checkpointDue(state, now), missed_checkpoints: 0 }
+}
+
+/**
+ * @param {Task} task
+ * @returns {Task}
+ */
+function reopen(task) {
+  return { ...task, status: 'open', holder_agent_id: null, next_checkpoint_due_at: null, missed_checkpoints: 0 }
+}
+
+/**
+ * @param {Task} task
+ * @param {Date} now
+ * @returns {Task}
+ */
+function settle(task, now) {
+  return { ...task, status: 'settled', settled_at: now }
+}
+
+/**
+ * @param {TaskState} state
+ * @param {Date} now
+ * @param {Effect[]} before
+ * @returns {[Task, Effect[]]}
+ */
+function submitted(state, now, before) {
+  const { task } = state
+  const reviewDue = new Date(now.getTime() + state.guild.piece_review_window_sec * 1000)
+  return [
+    { ...task, status: 'submitted', next_checkpoint_due_at: null, missed_checkpoints: 0, review_due_at: reviewDue },
+    [...before, event('task.submitted', task.publisher_agent_id), ...reviewJobs(reviewDue)],
+  ]
+}
+
+/**
+ * @param {Task} task
+ * @param {'released'|'timeout'} reason
+ * @returns {Effect[]}
+ */
+function releaseEffects(task, reason) {
+  return [{ type: 'hold_end', reason }, event('task.released', /** @type {string} */ (task.holder_agent_id)), event('task.released', task.publisher_agent_id)]
+}
+
+/**
+ * @param {string} openedBy
+ * @param {Date} now
+ * @returns {Effect[]}
+ */
+function disputeEffects(openedBy, now) {
+  return [{ type: 'dispute_open', opened_by_agent_id: openedBy }, job('dispute_arbitrate', now)]
+}
+
+/**
+ * 任务上板后的到期 job：过期无人接；擂台赛另加到点关闭。
+ * @param {Task} task
+ * @returns {Effect[]}
+ */
+function openJobs(task) {
+  switch (task.template) {
+    case 'piecework':
+      return [job('open_expire', task.deadline_at)]
+    case 'contest':
+      return [job('open_expire', task.deadline_at), job('contest_close', task.deadline_at)]
+    default:
+      throw new Error(`Unhandled template: ${task.template}, id: ${task.id}`)
+  }
+}
+
+/**
+ * @param {TaskState} state
+ * @param {Date} from
+ * @returns {Effect[]}
+ */
+function checkpointJobs(state, from) {
+  const due = checkpointDue(state, from)
+  return [job('checkpoint_warn', new Date(due.getTime() - HOUR_MS)), job('checkpoint_miss', due)]
+}
+
+/**
+ * @param {Date} reviewDue
+ * @returns {Effect[]}
+ */
+function reviewJobs(reviewDue) {
+  return [job('review_warn', new Date(reviewDue.getTime() - 2 * HOUR_MS)), job('review_auto_accept', reviewDue)]
+}
+
+/**
+ * @param {string} eventType
+ * @param {string|null} targetAgentId
+ * @returns {Effect}
+ */
+function event(eventType, targetAgentId) {
+  return { type: 'event', event_type: eventType, target_agent_id: targetAgentId }
+}
+
+/**
+ * @param {string} kind
+ * @param {Date} runAt
+ * @returns {Effect}
+ */
+function job(kind, runAt) {
+  return { type: 'job', kind, run_at: runAt }
+}
+
+/**
+ * @param {Task} task
+ * @param {Effect[]} effects
+ * @returns {TransitionResult}
+ */
+function ok(task, effects) {
+  return { ok: true, task, effects }
+}
+
+/**
+ * @param {'state_conflict'|'rule_violation'|'forbidden'} code
+ * @param {string} hint
+ * @returns {TransitionResult}
+ */
+function fail(code, hint) {
+  return { ok: false, code, hint }
+}
+
+/**
+ * @param {string} hint
+ * @returns {TransitionResult}
+ */
+function notAllowed(hint) {
+  return fail('forbidden', hint)
+}
diff --git a/packages/voko-exchange/test/transition.test.js b/packages/voko-exchange/test/transition.test.js
new file mode 100644
index 0000000..174ede5
--- /dev/null
+++ b/packages/voko-exchange/test/transition.test.js
@@ -0,0 +1,233 @@
+import { describe, expect, it } from 'vitest'
+import { taskFromRow, TASK_STATUSES } from '../src/task.js'
+import { publishStatus, TASK_ACTIONS, transition } from '../src/transition.js'
+
+const NOW = new Date('2026-10-12T12:00:00.000Z')
+const PAST = new Date('2026-10-12T06:00:00.000Z')
+const FUTURE = new Date('2026-10-13T12:00:00.000Z')
+const guild = { checkpoint_interval_sec: 21600, piece_review_window_sec: 86400, contest_review_window_sec: 259200 }
+
+const publisher = agent('ag_pub', 'u_pub')
+const holder = agent('ag_holder', 'u_holder')
+const taker = agent('ag_taker', 'u_taker')
+const entrant = { ...agent('ag_entrant', 'u_entrant'), is_entrant: true }
+const lead = { kind: 'lead', user_id: 'u_lead' }
+const operator = { kind: 'operator', user_id: 'u_ops' }
+const worker = { kind: 'worker' }
+
+function agent(agent_id, owner_user_id) {
+  return { kind: 'agent', agent_id, owner_user_id, max_rarity: 10, active_hold_count: 0, is_entrant: false }
+}
+
+/** 每个状态一条符合生产 schema 的任务行（到期类时间都已过，便于 worker 动作成立）。 */
+function stateFor(status, template = TEMPLATE_OF[status] ?? 'piecework', overrides = {}) {
+  const held = ['claimed', 'submitted', 'rework'].includes(status) || (status === 'disputed' && template === 'piecework')
+  const task = taskFromRow({
+    id: 't_1',
+    guild_id: 'g_1',
+    publisher_agent_id: 'ag_pub',
+    template,
+    title: 'Translate onboarding email',
+    spec: 'Translate to Japanese',
+    reward: 100,
+    rarity: 2,
+    deadline_at: PAST,
+    status,
+    client_request_key: 'req_1',
+    holder_agent_id: held ? 'ag_holder' : null,
+    next_checkpoint_due_at: status === 'claimed' ? PAST : null,
+    missed_checkpoints: 0,
+    rework_count: status === 'rework' ? 1 : 0,
+    review_due_at: ['submitted', 'reviewing'].includes(status) ? PAST : null,
+    settled_at: status === 'settled' ? PAST : null,
+    created_at: PAST,
+    updated_at: null,
+    ...overrides,
+  })
+  return { task, guild, publisher_owner_user_id: 'u_pub' }
+}
+
+const TEMPLATE_OF = { in_contest: 'contest', reviewing: 'contest' }
+
+/** 每个动作的合法发起者与参数。 */
+const ACTOR_OF = {
+  approve: lead,
+  reject_approval: lead,
+  claim: taker,
+  enter: taker,
+  cancel: publisher,
+  open_expire: worker,
+  edit: publisher,
+  checkpoint: holder,
+  checkpoint_miss: worker,
+  release: holder,
+  hold_timeout: worker,
+  transfer_accept: taker,
+  submit: holder,
+  accept: publisher,
+  reject: publisher,
+  review_auto_accept: worker,
+  contest_close: worker,
+  select_winner: publisher,
+  dispute: publisher,
+  resolve: operator,
+}
+const PARAMS_OF = {
+  edit: { add_reward: 50, deadline_at: FUTURE },
+  review_auto_accept: { winner_agent_id: 'ag_entrant' },
+  select_winner: { winner_agent_id: 'ag_entrant' },
+  resolve: { outcome: 'settled', winner_agent_id: 'ag_holder' },
+}
+
+/** SDD 状态转移表：status → action → 期望的新状态。表里没有的组合一律 state_conflict。 */
+const EXPECTED = {
+  pending_approval: { approve: 'open', reject_approval: 'cancelled' },
+  open: { claim: 'claimed', enter: 'in_contest', cancel: 'cancelled', open_expire: 'cancelled', edit: 'open' },
+  claimed: { checkpoint: 'claimed', checkpoint_miss: 'claimed', release: 'open', hold_timeout: 'open', transfer_accept: 'claimed', submit: 'submitted' },
+  in_contest: { enter: 'in_contest', submit: 'in_contest', contest_close: 'reviewing' },
+  submitted: { accept: 'settled', reject: 'rework', review_auto_accept: 'settled', dispute: 'disputed' },
+  reviewing: { select_winner: 'settled', review_auto_accept: 'settled', dispute: 'disputed' },
+  rework: { submit: 'submitted', dispute: 'disputed' },
+  disputed: { resolve: 'settled' },
+  settled: {},
+  cancelled: {},
+  refunded: {},
+}
+
+function run(state, type, actor = ACTOR_OF[type], params = PARAMS_OF[type]) {
+  return transition(state, { type, ...params }, actor, NOW)
+}
+
+const effectTypes = (result) => result.effects.map((effect) => effect.type === 'event' ? effect.event_type : effect.type === 'job' ? `job:${effect.kind}` : effect.type)
+
+describe('SM-01 transition()：11 个状态 × 全部动作', () => {
+  it('期望表覆盖全部状态', () => {
+    expect(Object.keys(EXPECTED)).toEqual([...TASK_STATUSES])
+  })
+
+  for (const status of TASK_STATUSES) {
+    for (const type of TASK_ACTIONS) {
+      const expected = EXPECTED[status][type]
+      it(`${status} × ${type} → ${expected ?? 'state_conflict'}`, () => {
+        const actor = status === 'in_contest' && type === 'submit' ? entrant : ACTOR_OF[type]
+        // open 的 enter 只对擂台赛成立；计件活 enter 的规则错误在下面单独断言。
+        const template = status === 'open' && type === 'enter' ? 'contest' : undefined
+        const result = run(stateFor(status, template), type, actor)
+        if (expected === undefined) {
+          expect(result).toMatchObject({ ok: false, code: 'state_conflict' })
+          return
+        }
+        expect(result.ok).toBe(true)
+        expect(result.task.status).toBe(expected)
+        // 新任务必须仍满足构造点的不变量。
+        expect(() => taskFromRow(result.task)).not.toThrow()
+      })
+    }
+  }
+
+  it('open 擂台赛：enter → in_contest，claim 是规则错误', () => {
+    const contest = stateFor('open', 'contest')
+    expect(run(contest, 'enter')).toMatchObject({ ok: true, task: { status: 'in_contest' }, effects: [{ type: 'entry_add', agent_id: 'ag_taker' }] })
+    expect(run(contest, 'claim')).toMatchObject({ ok: false, code: 'rule_violation' })
+    expect(run(stateFor('open'), 'enter')).toMatchObject({ ok: false, code: 'rule_violation' })
+  })
+
+  it('错误的发起者一律 forbidden', () => {
+    for (const status of TASK_STATUSES) {
+      for (const type of Object.keys(EXPECTED[status])) {
+        if (type === 'claim' || type === 'enter' || type === 'transfer_accept') continue
+        const stranger = ACTOR_OF[type].kind === 'agent' ? worker : agent('ag_stranger', 'u_stranger')
+        expect(run(stateFor(status), type, stranger), `${status} × ${type}`).toMatchObject({ ok: false, code: 'forbidden' })
+      }
+    }
+  })
+})
+
+describe('SM-01 副作用与平台规则', () => {
+  it('认领：开始持有、通知发布方、排检查点与超时 job', () => {
+    const result = run(stateFor('open', 'piecework', { deadline_at: FUTURE }), 'claim')
+    expect(effectTypes(result)).toEqual(['hold_start', 'task.claimed', 'job:checkpoint_warn', 'job:checkpoint_miss', 'job:hold_timeout'])
+    expect(result.task.holder_agent_id).toBe('ag_taker')
+    expect(result.task.next_checkpoint_due_at).toEqual(new Date('2026-10-12T18:00:00.000Z'))
+    expect(result.effects[2].run_at).toEqual(new Date('2026-10-12T17:00:00.000Z'))
+  })
+
+  it('自接自单、同主人、并发上限 → state_conflict；稀有度超等级 → rule_violation', () => {
+    const open = stateFor('open')
+    expect(run(open, 'claim', publisher)).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(open, 'claim', agent('ag_sibling', 'u_pub'))).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(open, 'claim', { ...taker, active_hold_count: 3 })).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(open, 'claim', { ...taker, active_hold_count: 2 }).ok).toBe(true)
+    expect(run(open, 'claim', { ...taker, max_rarity: 1 })).toMatchObject({ ok: false, code: 'rule_violation' })
+    expect(run(stateFor('open', 'contest'), 'enter', agent('ag_sibling', 'u_pub'))).toMatchObject({ ok: false, code: 'state_conflict' })
+  })
+
+  it('检查点缺一次只告警并顺延，缺两次释放回 open', () => {
+    const first = run(stateFor('claimed'), 'checkpoint_miss')
+    expect(first.task).toMatchObject({ status: 'claimed', missed_checkpoints: 1, next_checkpoint_due_at: new Date('2026-10-12T12:00:00.000Z') })
+    const second = run(stateFor('claimed', 'piecework', { missed_checkpoints: 1 }), 'checkpoint_miss')
+    expect(second.task).toMatchObject({ status: 'open', holder_agent_id: null, missed_checkpoints: 0 })
+    expect(effectTypes(second)).toEqual(['hold_end', 'task.released', 'task.released'])
+    expect(second.effects[0].reason).toBe('timeout')
+    expect(run(stateFor('claimed', 'piecework', { missed_checkpoints: 1 }), 'checkpoint').task.missed_checkpoints).toBe(0)
+  })
+
+  it('未到期的 worker 动作是过时 job，返回 state_conflict', () => {
+    expect(run(stateFor('open', 'piecework', { deadline_at: FUTURE }), 'open_expire')).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(stateFor('claimed', 'piecework', { deadline_at: FUTURE }), 'hold_timeout')).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(stateFor('claimed', 'piecework', { next_checkpoint_due_at: FUTURE }), 'checkpoint_miss')).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(stateFor('in_contest', 'contest', { deadline_at: FUTURE }), 'contest_close')).toMatchObject({ ok: false, code: 'state_conflict' })
+    expect(run(stateFor('submitted', 'piecework', { review_due_at: FUTURE }), 'review_auto_accept')).toMatchObject({ ok: false, code: 'state_conflict' })
+  })
+
+  it('提交开启验收窗口：计件活 24h，擂台赛关闭后 72h', () => {
+    const submitted = run(stateFor('claimed'), 'submit')
+    expect(submitted.task.review_due_at).toEqual(new Date('2026-10-13T12:00:00.000Z'))
+    expect(effectTypes(submitted)).toEqual(['hold_end', 'task.submitted', 'job:review_warn', 'job:review_auto_accept'])
+    expect(run(stateFor('in_contest'), 'contest_close').task.review_due_at).toEqual(new Date('2026-10-15T12:00:00.000Z'))
+  })
+
+  it('驳回两次进返工，第 3 次进仲裁', () => {
+    expect(run(stateFor('submitted'), 'reject').task).toMatchObject({ status: 'rework', rework_count: 1, review_due_at: null })
+    expect(run(stateFor('submitted', 'piecework', { rework_count: 1 }), 'reject').task).toMatchObject({ status: 'rework', rework_count: 2 })
+    const third = run(stateFor('submitted', 'piecework', { rework_count: 2 }), 'reject')
+    expect(third.task).toMatchObject({ status: 'disputed', rework_count: 2 })
+    expect(effectTypes(third)).toEqual(['dispute_open', 'job:dispute_arbitrate'])
+  })
+
+  it('结算与退款的托管动作', () => {
+    expect(run(stateFor('submitted'), 'accept').effects[0]).toEqual({ type: 'escrow_settle', winner_agent_id: 'ag_holder' })
+    expect(run(stateFor('reviewing'), 'select_winner').effects[0]).toEqual({ type: 'escrow_settle', winner_agent_id: 'ag_entrant' })
+    const noWinner = run(stateFor('reviewing'), 'review_auto_accept', worker, { winner_agent_id: null })
+    expect(noWinner.task.status).toBe('refunded')
+    expect(noWinner.effects[0]).toEqual({ type: 'escrow_refund' })
+    expect(run(stateFor('disputed'), 'resolve', operator, { outcome: 'refunded', winner_agent_id: null }).task.status).toBe('refunded')
+    for (const type of ['cancel', 'open_expire']) expect(run(stateFor('open'), type).effects).toEqual([{ type: 'escrow_refund' }])
+  })
+
+  it('修改只能加赏金或延长截止', () => {
+    const edited = run(stateFor('open'), 'edit')
+    expect(edited.task).toMatchObject({ reward: 150, deadline_at: FUTURE })
+    expect(effectTypes(edited)).toEqual(['escrow_topup', 'job:open_expire'])
+    expect(run(stateFor('open'), 'edit', publisher, { add_reward: 0, deadline_at: null })).toMatchObject({ ok: false, code: 'rule_violation' })
+    expect(run(stateFor('open', 'piecework', { deadline_at: FUTURE }), 'edit', publisher, { add_reward: 0, deadline_at: PAST })).toMatchObject({ ok: false, code: 'rule_violation' })
+  })
+
+  it('争议只能由发布方或接单方发起', () => {
+    expect(run(stateFor('submitted'), 'dispute', holder).task.status).toBe('disputed')
+    expect(run(stateFor('reviewing'), 'dispute', entrant).task.status).toBe('disputed')
+    expect(run(stateFor('submitted'), 'dispute', taker)).toMatchObject({ ok: false, code: 'forbidden' })
+  })
+
+  it('发布时的初始状态', () => {
+    expect(publishStatus({ require_lead_approval: true, publisher_role: 'company' })).toBe('pending_approval')
+    expect(publishStatus({ require_lead_approval: false, publisher_role: 'company' })).toBe('open')
+    expect(publishStatus({ require_lead_approval: true, publisher_role: 'member' })).toBe('open')
+  })
+
+  it('未知动作与非法行直接 throw', () => {
+    expect(() => transition(stateFor('open'), { type: 'teleport' }, worker, NOW)).toThrow(/Unhandled action: teleport, id: t_1/)
+    expect(() => stateFor('archived')).toThrow(/Unhandled status: archived, id: t_1/)
+    expect(() => stateFor('claimed', 'piecework', { holder_agent_id: null })).toThrow(/holder_agent_id missing/)
+  })
+})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index b51f63a..3e88489 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -294,7 +294,11 @@ importers:
 
   packages/voko-clearing: {}
 
-  packages/voko-exchange: {}
+  packages/voko-exchange:
+    devDependencies:
+      vitest:
+        specifier: ^2.1.4
+        version: 2.1.9(@types/node@24.13.2)(jsdom@25.0.1)(sass@1.101.0)
 
 packages: