diff --git a/services/frontend/src/components/island/SeatRows.vue b/services/frontend/src/components/island/SeatRows.vue
index 3bfe74a33..9ebab8087 100644
--- a/services/frontend/src/components/island/SeatRows.vue
+++ b/services/frontend/src/components/island/SeatRows.vue
@@ -30,12 +30,26 @@ export interface SeatRow {
   srcset?: string
 }
 
-const props = defineProps<{
+const props = withDefaults(defineProps<{
   rows: SeatRow[]
   /** The colour the plates, the roles and the chevrons are drawn in. */
   accent: string
   /** What each row's data-testid is built from, since a page names its own rows. */
   testidPrefix: string
+  /**
+   * Whether a row offers a way to change it, and the stack a way to add another.
+   *
+   * Decided by the page, which knows who is reading. Nothing here is a guard: the rows are
+   * handed a boolean, and what a refused request does is the api's answer.
+   */
+  mayEdit?: boolean
+  /** What the way in at the end of the stack is called, in whatever a row is called here. */
+  addLabel?: string
+}>(), {mayEdit: false, addLabel: "Add"})
+
+const emit = defineEmits<{
+  (event: "edit", id: SeatRow["id"]): void
+  (event: "add"): void
 }>()
 
 /**
@@ -77,6 +91,7 @@ const toggle = (row: SeatRow) => {
 <template>
   <div
     class="seat-rows"
+    :class="{'seat-rows--editable': mayEdit}"
     :data-testid="`${testidPrefix}-seat-rows`"
     :style="{'--accent': accent}"
   >
@@ -166,7 +181,59 @@ const toggle = (row: SeatRow) => {
       >
         <p>{{ row.blurb }}</p>
       </div>
+
+      <!--
+        Offered only to somebody who may take it up, and over the row rather than inside it:
+        the head is a button wherever a blurb was written, and a button inside a button is not
+        markup. It waits to be approached, because a stack of rows under a column of pencils
+        reads as a form rather than as the association's history.
+      -->
+      <button
+        v-if="mayEdit"
+        :aria-label="`Edit ${row.name}`"
+        class="seat-row__edit"
+        :data-testid="`${testidPrefix}-seat-edit-${row.id}`"
+        type="button"
+        @click="emit('edit', row.id)"
+      >
+        <svg
+          aria-hidden="true"
+          fill="none"
+          stroke="currentColor"
+          stroke-width="2"
+          viewBox="0 0 24 24"
+        >
+          <path d="M4 20h4L19 9a2.8 2.8 0 0 0-4-4L4 16v4Z" />
+        </svg>
+      </button>
     </article>
+
+    <!--
+      Another seat is added at the end of the stack, which is where its absence is noticed. It
+      stands rather than waiting to be approached: there is no row under the pointer for it to
+      belong to, and a board that gained a sixth member has nothing yet to hover over.
+    -->
+    <button
+      v-if="mayEdit"
+      class="seat-row__add"
+      :data-testid="`${testidPrefix}-seat-add`"
+      type="button"
+      @click="emit('add')"
+    >
+      <span
+        aria-hidden="true"
+        class="seat-row__plus island-plus"
+      >
+        <svg
+          class="island-plus__edge"
+          fill="none"
+          viewBox="0 0 100 100"
+        >
+          <path d="M38 2 H62 V38 H98 V62 H62 V98 H38 V62 H2 V38 H38 Z" />
+        </svg>
+      </span>
+      <span class="seat-row__add-label">{{ addLabel }}</span>
+    </button>
   </div>
 </template>
 
@@ -187,6 +254,7 @@ const toggle = (row: SeatRow) => {
 }
 
 .seat-row {
+  position: relative;
   border-bottom: 1px solid var(--color-hairline);
 }
 
@@ -213,6 +281,84 @@ button.seat-row__head {
   cursor: pointer;
 }
 
+/* Room for the pencil, so it never lands on the chevron beside it. Taken on every row rather
+   than only the ones with a chevron, or the column of them would be ragged. */
+.seat-rows--editable .seat-row__head {
+  padding-right: 3rem;
+}
+
+/*
+ * Hidden rather than transparent, for the reason the strip's own affordance gives: one that is
+ * merely see-through still answers a click, and a test asking whether it is on screen would be
+ * told that it is.
+ */
+.seat-row__edit {
+  position: absolute;
+  top: 0.85rem;
+  right: 0.35rem;
+  z-index: 2;
+  visibility: hidden;
+  display: grid;
+  place-items: center;
+  width: 2.25rem;
+  height: 2.25rem;
+  background: none;
+  border: 0;
+  color: var(--color-chalk);
+  cursor: pointer;
+}
+
+.seat-row__edit svg {
+  width: 1.25rem;
+  height: 1.25rem;
+}
+
+/* Revealed by the row rather than by itself: hidden means unfocusable, so an affordance that
+   waited to be focused could never be reached. The row takes the focus first and the next tab
+   lands here. */
+.seat-row:hover .seat-row__edit,
+.seat-row:focus-within .seat-row__edit {
+  visibility: visible;
+}
+
+/* No pointer to hover with, so there is no state to reveal it from. */
+@media (hover: none) {
+  .seat-row__edit {
+    visibility: visible;
+  }
+}
+
+.seat-row__add {
+  display: flex;
+  align-items: center;
+  gap: 0.85rem;
+  width: 100%;
+  padding: 0.85rem 0.5rem;
+  background: none;
+  border: 0;
+  border-bottom: 1px solid var(--color-hairline);
+  text-align: left;
+  cursor: pointer;
+}
+
+/* The same square the plates above it are, so the column stays a column past the last seat. */
+.seat-row__plus {
+  flex: none;
+  width: calc(var(--plate) * 0.42);
+}
+
+.seat-row__add-label {
+  font-family: var(--font-display);
+  font-size: clamp(1rem, 2.6vw, 1.4rem);
+  text-transform: uppercase;
+  color: var(--color-ash);
+}
+
+.seat-row__add:hover .seat-row__add-label,
+.seat-row__add:focus-visible .seat-row__add-label {
+  color: var(--color-chalk);
+}
+
 /*
  * The portrait and the initials are one shape drawn two ways — cut on the island's own diagonal
  * and on the same lean as the bands above it, so the column belongs to the page rather than
@@ -326,6 +472,7 @@ button.seat-row__head:hover .seat-row__name {
 }
 
 @media (prefers-reduced-motion: reduce) {
+  .seat-row__plus,
   .seat-row__chevron,
   .seat-row__said {
     transition: none;
diff --git a/services/frontend/src/domains/boards/adapters/boards.ts b/services/frontend/src/domains/boards/adapters/boards.ts
index af48d2605..0efd9a607 100644
--- a/services/frontend/src/domains/boards/adapters/boards.ts
+++ b/services/frontend/src/domains/boards/adapters/boards.ts
@@ -72,7 +72,7 @@ export const storeSeatPortrait: PictureStore = storePicture(FileType.BOARD_PORTR
  * A seat's name with its nickname back in the middle of it, the way the history was written:
  * `Roos "SkyeWolf" Kruk`. The two are recorded apart so anything can ask for either.
  */
-export function seatTitle(seat: BoardSeat): string {
+export function seatTitle(seat: {name?: string | null; nickname?: string | null}): string {
   const name = seat.name ?? ""
   if (!seat.nickname) return name
   const [first, ...rest] = name.split(" ")
@@ -165,20 +165,35 @@ export async function dropBoard(id: number): Promise<{ok: true} | Refused> {
   return {ok: true}
 }
 
-export async function addSeat(
+/**
+ * A seat as it is written down: the role it held, who held it, and when.
+ *
+ * `displayName` is the name the seat stands under rather than the account's. Most of the people
+ * who have held one never had an account here, so the name is the seat's own and an account is
+ * something a seat may additionally have.
+ */
+export interface SeatWrite {
+  role: string
+  startDate: string
+  endDate?: string | null
+  userId?: number | null
+  displayName?: string | null
+  nickname?: string | null
+  description?: string | null
+  image?: string | null
+  portrait?: string | null
+}
+
+/**
+ * A seat written down, or the api's own words for why it was not.
+ *
+ * The sdk hands a refusal back as a body rather than throwing, so a dialog that only read
+ * `data` could not tell a rejected date or a rejected upload from a save that worked.
+ */
+export async function addSeatOrReason(
   boardId: number,
-  seat: {
-    role: string
-    startDate: string
-    endDate?: string | null
-    userId?: number | null
-    displayName?: string | null
-    nickname?: string | null
-    description?: string | null
-    image?: string | null
-    portrait?: string | null
-  },
-): Promise<BoardSeat | null> {
+  seat: SeatWrite,
+): Promise<{ok: true; seat: BoardSeat} | Refused> {
   const res = await addMember({
     path: {boardId},
     body: {
@@ -193,23 +208,22 @@ export async function addSeat(
       portrait: seat.portrait ?? undefined,
     },
   })
-  return res.data ? withPortrait(res.data) : null
+  if (res.error || !res.data) {
+    return {ok: false, reason: reasonFor(res.error, "That seat could not be added.")}
+  }
+  return {ok: true, seat: withPortrait(res.data)}
 }
 
-export async function saveSeat(
+export async function addSeat(boardId: number, seat: SeatWrite): Promise<BoardSeat | null> {
+  const added = await addSeatOrReason(boardId, seat)
+  return added.ok ? added.seat : null
+}
+
+export async function saveSeatOrReason(
   boardId: number,
   id: number,
-  seat: {
-    role: string
-    startDate: string
-    endDate?: string | null
-    displayName?: string | null
-    nickname?: string | null
-    description?: string | null
-    image?: string | null
-    portrait?: string | null
-  },
-): Promise<BoardSeat | null> {
+  seat: Omit<SeatWrite, "userId">,
+): Promise<{ok: true; seat: BoardSeat} | Refused> {
   const res = await updateMember({
     path: {boardId, id},
     body: {
@@ -223,19 +237,54 @@ export async function saveSeat(
       portrait: seat.portrait ?? undefined,
     },
   })
-  return res.data ? withPortrait(res.data) : null
+  if (res.error || !res.data) {
+    return {ok: false, reason: reasonFor(res.error, "That seat could not be saved.")}
+  }
+  return {ok: true, seat: withPortrait(res.data)}
+}
+
+export async function saveSeat(
+  boardId: number,
+  id: number,
+  seat: Omit<SeatWrite, "userId">,
+): Promise<BoardSeat | null> {
+  const saved = await saveSeatOrReason(boardId, id, seat)
+  return saved.ok ? saved.seat : null
 }
 
 /** A null member detaches the seat, which keeps standing under its own name. */
+export async function linkSeatMemberOrReason(
+  boardId: number,
+  id: number,
+  userId: number | null,
+): Promise<{ok: true; seat: BoardSeat} | Refused> {
+  const res = await linkMember({path: {boardId, id}, body: {userId: userId ?? undefined}})
+  if (res.error || !res.data) {
+    const what = userId == null ? "detached" : "linked to that account"
+    return {ok: false, reason: reasonFor(res.error, `That seat could not be ${what}.`)}
+  }
+  return {ok: true, seat: withPortrait(res.data)}
+}
+
 export async function linkSeatMember(
   boardId: number,
   id: number,
   userId: number | null,
 ): Promise<BoardSeat | null> {
-  const res = await linkMember({path: {boardId, id}, body: {userId: userId ?? undefined}})
-  return res.data ? withPortrait(res.data) : null
+  const linked = await linkSeatMemberOrReason(boardId, id, userId)
+  return linked.ok ? linked.seat : null
+}
+
+/** A seat is somebody's place in the association's history, so a refusal is worth reporting. */
+export async function dropSeatOrReason(
+  boardId: number,
+  id: number,
+): Promise<{ok: true} | Refused> {
+  const res = await removeMember({path: {boardId, id}})
+  if (res.error) return {ok: false, reason: reasonFor(res.error, "That seat could not be removed.")}
+  return {ok: true}
 }
 
 export async function dropSeat(boardId: number, id: number): Promise<void> {
-  await removeMember({path: {boardId, id}})
+  await dropSeatOrReason(boardId, id)
 }
diff --git a/services/frontend/src/domains/boards/island/SeatDialog.vue b/services/frontend/src/domains/boards/island/SeatDialog.vue
new file mode 100644
index 000000000..820cd03db
--- /dev/null
+++ b/services/frontend/src/domains/boards/island/SeatDialog.vue
@@ -0,0 +1,569 @@
+<script lang="ts" setup>
+import {computed, ref, watch} from "vue"
+import IslandDialog from "@/components/island/IslandDialog.vue"
+import ConfirmDialog from "@/components/island/ConfirmDialog.vue"
+import ImagePicker from "@/components/island/ImagePicker.vue"
+import IslandPicker from "@/components/island/IslandPicker.vue"
+import type {Picture} from "@/components/island/pictures"
+import {loadMembers, type Member} from "@/domains/user"
+import {
+  addSeatOrReason,
+  dropSeatOrReason,
+  linkSeatMemberOrReason,
+  saveSeatOrReason,
+  seatTitle,
+  storeSeatPortrait,
+  type BoardSeat,
+} from "../adapters/boards"
+
+/**
+ * One seat written down or corrected, from the page it is read on.
+ *
+ * Everything a seat is: the name it stands under, the nickname the history knows it by, the
+ * role in the board's own words, the portrait, the account it belongs to, the stretch it was
+ * served and what the person wrote about themselves. One dialog for adding and for
+ * correcting, because they are the same fields.
+ *
+ * A seat is not a person. The name is the seat's own, so somebody who never had an account
+ * here is still in the history — and an account is something a seat may additionally have.
+ * That link and the serving dates are what the cohort module reads to answer "was on the
+ * board that year", which is why the dates are editable rather than silently inherited: a
+ * mid-year handover is recorded truthfully rather than credited as a full year.
+ *
+ * A refusal keeps what was typed. Losing seven fields to find out what the objection was
+ * would mean typing them again to ask.
+ */
+defineOptions({name: "SeatDialog"})
+
+const props = withDefaults(defineProps<{
+  open: boolean
+  /** The board the seat sits on, which is the only board this dialog writes to. */
+  boardId: number | null
+  /** The seat being corrected, or nothing where one is being added. */
+  seat: BoardSeat | null
+  /** The board's own term, which a new seat is pre-filled from. */
+  boardStart?: string | null
+  boardEnd?: string | null
+  accent?: string
+}>(), {boardStart: null, boardEnd: null, accent: undefined})
+
+const emit = defineEmits<{
+  (event: "update:open", open: boolean): void
+  (event: "saved"): void
+  (event: "removed"): void
+}>()
+
+const DESCRIPTION_CAP = 4000
+
+const adding = computed(() => props.seat == null)
+
+const name = ref("")
+/** The seat's own rather than the member's, and recorded apart from the name it sits inside. */
+const nickname = ref("")
+const role = ref("")
+const description = ref("")
+const startDate = ref("")
+const endDate = ref("")
+/** The account the seat belongs to, where it belongs to one. Most of the history does not. */
+const userId = ref<number | null>(null)
+/**
+ * The portrait now held.
+ *
+ * Chosen bytes go into storage as they are chosen and reach the seat only when this dialog is
+ * saved, which is what lets cancelling leave the seat on the picture it had. The picker's own
+ * doc comment is the long version.
+ */
+const portrait = ref<Picture | null>(null)
+const failure = ref<string | null>(null)
+const saving = ref(false)
+
+const members = ref<Member[]>([])
+
+/** The day part of a date, so a stored timestamp still fills a date field. */
+const dayOf = (date?: string | null): string => (date ?? "").trim().slice(0, 10)
+
+/*
+ * Opening fills the form from the seat as it stands, and a seat being added from the board's
+ * own term: the common case is somebody who served the whole year, and it needs no typing.
+ *
+ * The members are read once and kept, because opening the dialog on the next seat asks the
+ * same question of the same list.
+ */
+watch(() => [props.open, props.seat] as const, async ([open]) => {
+  if (!open) return
+  const seat = props.seat
+  name.value = seat?.name ?? ""
+  nickname.value = seat?.nickname ?? ""
+  role.value = seat?.role ?? ""
+  description.value = seat?.description ?? ""
+  startDate.value = dayOf(seat?.startDate ?? props.boardStart)
+  endDate.value = dayOf(seat?.endDate ?? props.boardEnd)
+  userId.value = seat?.userId ?? null
+  portrait.value = seat?.portrait ?? null
+  failure.value = null
+  if (members.value.length === 0) members.value = await loadMembers()
+}, {immediate: true})
+
+const title = computed(() => (props.seat ? `Edit ${seatTitle(props.seat)}` : "Add a seat"))
+
+/** Every member, as the picker asks for them: their name, and their address to tell two apart. */
+const memberOptions = computed(() =>
+  members.value.map(one => ({key: String(one.id), label: one.name, note: one.email ?? undefined})))
+
+const nameOf = (id: number | null): string =>
+  (id == null ? "" : members.value.find(one => one.id === id)?.name ?? `Member ${id}`)
+
+/** How the page will publish the name, so the quoting is visible before it is saved. */
+const published = computed(() => (name.value.trim() === ""
+  ? ""
+  : seatTitle({name: name.value.trim(), nickname: nickname.value.trim() || null})))
+
+/**
+ * A seat has to stand under a name and say what it was; the rest of it may be unknown.
+ *
+ * The dates are the api's own requirement rather than this dialog's — a seat records the
+ * stretch it was served, and that is what the association is asked about.
+ */
+const complete = computed(() =>
+  name.value.trim() !== "" && role.value.trim() !== "" && startDate.value !== "")
+
+const confirming = ref(false)
+const removing = ref(false)
+const removalFailure = ref<string | null>(null)
+
+/** What removing this seat would take with it, said before the question is put. */
+const question = computed(() => {
+  const seat = props.seat
+  if (!seat) return ""
+  const who = seatTitle(seat)
+  const said = seat.description?.trim()
+    ? " What they wrote about themselves goes with it."
+    : ""
+  return `${who} held ${seat.role} on this board. Removing the seat takes it out of the `
+    + `association's history.${said}`
+})
+
+const askToRemove = () => {
+  if (!props.seat) return
+  failure.value = null
+  removalFailure.value = null
+  confirming.value = true
+}
+
+const removeSeat = async () => {
+  const seat = props.seat
+  const boardId = props.boardId
+  if (!seat || boardId == null || removing.value) return
+  removing.value = true
+  removalFailure.value = null
+  try {
+    const result = await dropSeatOrReason(boardId, seat.id)
+    if (!result.ok) {
+      // Nothing has gone, so the question stands and says why.
+      removalFailure.value = result.reason
+      return
+    }
+    emit("removed")
+    confirming.value = false
+    emit("update:open", false)
+  } finally {
+    removing.value = false
+  }
+}
+
+const submit = async () => {
+  const boardId = props.boardId
+  if (!complete.value || saving.value || boardId == null) return
+  saving.value = true
+  failure.value = null
+  try {
+    const written = {
+      role: role.value.trim(),
+      startDate: startDate.value,
+      endDate: endDate.value || null,
+      displayName: name.value.trim(),
+      nickname: nickname.value.trim() || null,
+      description: description.value.trim() || null,
+      // The asset file name the early history still points at, carried through rather than
+      // shown: a save replaces every field, so leaving it out would quietly clear it.
+      image: props.seat?.image ?? null,
+      portrait: portrait.value?.path ?? null,
+    }
+    const seat = props.seat
+    if (seat == null) {
+      // The account goes with the seat as it is written down: adding takes it in one request.
+      const added = await addSeatOrReason(boardId, {...written, userId: userId.value})
+      if (!added.ok) {
+        failure.value = added.reason
+        return
+      }
+    } else {
+      const saved = await saveSeatOrReason(boardId, seat.id, written)
+      if (!saved.ok) {
+        failure.value = saved.reason
+        return
+      }
+      // The link is its own endpoint, and asked only where it changed: detaching is a null
+      // member, and a seat with none carries on standing under its own name.
+      if (userId.value !== (seat.userId ?? null)) {
+        const linked = await linkSeatMemberOrReason(boardId, seat.id, userId.value)
+        if (!linked.ok) {
+          failure.value = linked.reason
+          return
+        }
+      }
+    }
+    emit("saved")
+    emit("update:open", false)
+  } finally {
+    saving.value = false
+  }
+}
+</script>
+
+<template>
+  <island-dialog
+    :accent="accent"
+    :open="open"
+    testid="seat-dialog"
+    :title="title"
+    @update:open="emit('update:open', $event)"
+  >
+    <form
+      id="seat-dialog-form"
+      class="seat-form"
+      @submit.prevent="submit"
+    >
+      <div class="seat-form__row">
+        <label class="seat-form__field">
+          <span class="seat-form__label">Name</span>
+          <input
+            v-model="name"
+            class="seat-form__input"
+            data-testid="seat-dialog-name"
+            maxlength="255"
+            required
+            type="text"
+          >
+        </label>
+        <label class="seat-form__field">
+          <span class="seat-form__label">Nickname</span>
+          <input
+            v-model="nickname"
+            class="seat-form__input"
+            data-testid="seat-dialog-nickname"
+            maxlength="255"
+            type="text"
+          >
+        </label>
+      </div>
+
+      <!-- The two together, quoted, which is the one string a reader has always been shown. -->
+      <span
+        v-if="published"
+        class="seat-form__hint"
+        data-testid="seat-dialog-published"
+      >Reads as {{ published }}</span>
+
+      <label class="seat-form__field">
+        <span class="seat-form__label">Role</span>
+        <input
+          v-model="role"
+          class="seat-form__input"
+          data-testid="seat-dialog-role"
+          maxlength="255"
+          placeholder="Secretary and Commissioner of the Esports Lounge"
+          required
+          type="text"
+        >
+        <span class="seat-form__hint">
+          In the board's own words, not from a list: nine years of boards have renamed and
+          combined their offices
+        </span>
+      </label>
+
+      <!-- Held until Save, like every other field here: closing without saving leaves the seat
+           on the portrait it had. Square, because a portrait is drawn on a square plate. -->
+      <image-picker
+        label="Portrait"
+        :picture="portrait"
+        shape="icon"
+        :store="storeSeatPortrait"
+        testid="seat-dialog-portrait"
+        @update:picture="portrait = $event"
+      />
+
+      <div class="seat-form__field">
+        <span class="seat-form__label">Account</span>
+        <!--
+          Shown as attached rather than as a value in the box, because detaching is a different
+          act from choosing again and the two must not be the same gesture a pixel apart.
+        -->
+        <span
+          v-if="userId != null"
+          class="seat-form__attached"
+          data-testid="seat-dialog-attached"
+        >
+          {{ nameOf(userId) }}
+          <button
+            :aria-label="`Detach ${nameOf(userId)}`"
+            class="seat-form__detach"
+            data-testid="seat-dialog-detach"
+            type="button"
+            @click="userId = null"
+          >&times;</button>
+        </span>
+        <island-picker
+          empty-note="Nobody has an account here yet."
+          :options="memberOptions"
+          placeholder="No account — search a member"
+          :selected-key="userId == null ? null : String(userId)"
+          testid-prefix="seat-dialog-member"
+          @pick="key => userId = Number(key)"
+        />
+        <span class="seat-form__hint">
+          Most people who have sat on a board never had an account here. A seat with none still
+          records the board that sat.
+        </span>
+      </div>
+
+      <div class="seat-form__row">
+        <label class="seat-form__field">
+          <span class="seat-form__label">Took the seat</span>
+          <input
+            v-model="startDate"
+            class="seat-form__input"
+            data-testid="seat-dialog-start"
+            required
+            type="date"
+          >
+        </label>
+        <label class="seat-form__field">
+          <span class="seat-form__label">Left it</span>
+          <input
+            v-model="endDate"
+            class="seat-form__input"
+            data-testid="seat-dialog-end"
+            type="date"
+          >
+        </label>
+      </div>
+
+      <span class="seat-form__hint">
+        Taken from the board, and worth correcting for a handover part-way through the year:
+        this is what the association is asked when it answers who served in a given window.
+      </span>
+
+      <label class="seat-form__field">
+        <span class="seat-form__label">Blurb</span>
+        <textarea
+          v-model="description"
+          class="seat-form__input seat-form__input--tall"
+          data-testid="seat-dialog-description"
+          :maxlength="DESCRIPTION_CAP"
+          rows="4"
+        />
+        <span class="seat-form__hint">What they wrote about themselves, in their own words</span>
+      </label>
+
+      <p
+        v-if="failure"
+        class="seat-form__failure"
+        data-testid="seat-dialog-failure"
+        role="alert"
+      >
+        {{ failure }}
+      </p>
+    </form>
+
+    <!-- In the footer, like the other dialogs on the island. Save names the form it submits
+         rather than sitting inside it, which is what lets it stand out here. -->
+    <template #footer>
+      <div class="seat-form__actions">
+        <button
+          v-if="!adding"
+          class="seat-form__button seat-form__button--drop"
+          data-testid="seat-dialog-remove"
+          type="button"
+          @click="askToRemove"
+        >
+          Remove
+        </button>
+        <button
+          class="seat-form__button seat-form__button--ghost"
+          data-testid="seat-dialog-cancel"
+          type="button"
+          @click="emit('update:open', false)"
+        >
+          Cancel
+        </button>
+        <button
+          class="seat-form__button seat-form__button--go"
+          data-testid="seat-dialog-save"
+          :disabled="!complete || saving"
+          form="seat-dialog-form"
+          type="submit"
+        >
+          {{ saving ? "Saving" : "Save" }}
+        </button>
+      </div>
+    </template>
+  </island-dialog>
+
+  <confirm-dialog
+    :accent="accent"
+    confirm-label="Remove the seat"
+    :failure="removalFailure"
+    :open="confirming"
+    :question="question"
+    testid="seat-remove-dialog"
+    title="Remove this seat?"
+    :working="removing"
+    @confirm="removeSeat"
+    @update:open="confirming = $event"
+  />
+</template>
+
+<style>
+/* Unscoped: the dialog is portalled out of this component's subtree. */
+.seat-form {
+  display: flex;
+  flex-direction: column;
+  gap: 0.9rem;
+  padding-bottom: 0.35rem;
+}
+
+.seat-form__row {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.85rem;
+}
+
+.seat-form__field {
+  display: flex;
+  flex: 1;
+  flex-direction: column;
+  gap: 0.3rem;
+  min-width: 0;
+}
+
+.seat-form__label {
+  padding: 0;
+  font-family: var(--font-display);
+  font-size: 0.62rem;
+  color: var(--color-ash);
+  letter-spacing: 0.1em;
+  text-transform: uppercase;
+}
+
+.seat-form__hint {
+  font-size: 0.72rem;
+  color: color-mix(in oklab, var(--color-ash) 80%, transparent);
+  word-break: break-word;
+}
+
+/* One field style across the island: flat, square, and lit by the focus ring rather than by
+   a border that competes with the labels above it. */
+.seat-form__input {
+  width: 100%;
+  padding: 0.55rem 0.75rem;
+  font-family: inherit;
+  font-size: 0.92rem;
+  color: var(--color-chalk);
+  background-color: color-mix(in oklab, var(--color-chalk) 7%, transparent);
+  border: 0;
+}
+
+.seat-form__input::placeholder {
+  color: var(--color-ash);
+}
+
+.seat-form__input--tall {
+  resize: vertical;
+}
+
+.seat-form__input:focus-visible {
+  outline: none;
+  border-color: var(--dialog-accent, var(--color-brand));
+}
+
+/* The account as a fact about the seat, with the one way to undo it beside it. */
+.seat-form__attached {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 0.5rem;
+  padding: 0.4rem 0.5rem 0.4rem 0.75rem;
+  background-color: color-mix(in oklab, var(--dialog-accent, var(--color-brand)) 16%, transparent);
+  font-size: 0.9rem;
+  color: var(--color-chalk);
+}
+
+.seat-form__detach {
+  flex: none;
+  padding: 0 0.35rem;
+  background: none;
+  border: 0;
+  color: var(--color-ash);
+  font-size: 1.1rem;
+  line-height: 1;
+  cursor: pointer;
+}
+
+.seat-form__detach:hover,
+.seat-form__detach:focus-visible {
+  color: var(--color-chalk);
+}
+
+.seat-form__failure {
+  margin: 0;
+  color: var(--color-danger);
+  font-size: 0.85rem;
+}
+
+/* Its own rule and its own spacing: see the footer in IslandDialog. */
+.seat-form__actions {
+  display: flex;
+  gap: 0.5rem;
+  justify-content: flex-end;
+  margin-top: 1rem;
+  padding-top: 0.85rem;
+  border-top: 1px solid color-mix(in oklab, var(--color-chalk) 12%, transparent);
+}
+
+.seat-form__button {
+  padding: 0.45rem 0.9rem;
+  border: 1px solid color-mix(in oklab, var(--color-chalk) 16%, transparent);
+  color: var(--color-chalk);
+  cursor: pointer;
+  font-family: inherit;
+  font-size: 0.85rem;
+}
+
+.seat-form__button--ghost {
+  background: transparent;
+}
+
+/* First in the row and set apart, the way the esports dialogs set their own removal apart. */
+.seat-form__button--drop {
+  margin-right: auto;
+  background: color-mix(in oklab, var(--color-danger-tint) 18%, transparent);
+  color: var(--color-danger-ink);
+}
+
+.seat-form__button--drop:hover {
+  background: color-mix(in oklab, var(--color-danger-tint) 34%, transparent);
+  color: var(--color-danger-ink-strong);
+}
+
+.seat-form__button--go {
+  background: var(--dialog-accent, var(--color-brand));
+  border-color: transparent;
+  color: var(--color-void);
+}
+
+.seat-form__button:disabled {
+  cursor: not-allowed;
+  opacity: 0.5;
+}
+</style>
diff --git a/services/frontend/src/pages/Board.vue b/services/frontend/src/pages/Board.vue
index aee0f3c60..b0c89b9cb 100644
--- a/services/frontend/src/pages/Board.vue
+++ b/services/frontend/src/pages/Board.vue
@@ -23,6 +23,7 @@ import {
   seatsInOrder,
 } from "@/domains/boards"
 import {seatTitle, type Board, type BoardSeat} from "@/domains/boards/adapters/boards"
+import SeatDialog from "@/domains/boards/island/SeatDialog.vue"
 import {$require} from "@/plugins/require"
 
 /**
@@ -195,6 +196,32 @@ const boardRemoved = async () => {
   void router.push({query})
   await refresh()
 }
+
+/**
+ * The seat being filled in, and whether the dialog is open on one.
+ *
+ * The seat itself rather than its id, so the dialog is handed what the page already read and
+ * asks the api nothing to open. Nothing is held for a seat being added: the dialog fills its
+ * dates from the board's own term instead.
+ */
+const seatOpen = ref(false)
+const editingSeat = ref<BoardSeat | null>(null)
+
+/** The rows name a seat by whatever id they were handed, which here is always the seat's. */
+const editSeat = (id: number | string) => {
+  editingSeat.value = seats.value.find(seat => seat.id === id) ?? null
+  seatOpen.value = true
+}
+
+const addSeat = () => {
+  editingSeat.value = null
+  seatOpen.value = true
+}
+
+/** A seat written down, corrected or removed is read again, so the page shows what was saved. */
+const seatSaved = () => {
+  void refresh()
+}
 </script>
 
 <template>
@@ -315,15 +342,29 @@ const boardRemoved = async () => {
             </p>
           </section>
 
+          <!-- Also where a board has nobody on it yet, so long as the reader may seat
+               somebody: the way in is at the end of the stack, and an empty stack is exactly
+               where it is needed. -->
           <section
-            v-if="seats.length > 0"
+            v-if="seats.length > 0 || mayEdit"
             class="mx-auto w-full max-w-4xl px-4 pb-10 sm:px-8"
             data-testid="board-seats"
           >
+            <p
+              v-if="seats.length === 0"
+              class="pt-2 pb-4 font-body text-sm text-ash"
+              data-testid="board-no-seats"
+            >
+              No seats are recorded on this board yet.
+            </p>
             <seat-rows
               :accent="accent"
+              add-label="Add a seat"
+              :may-edit="mayEdit"
               :rows="seatsAsRows"
               testid-prefix="board"
+              @add="addSeat"
+              @edit="editSeat"
             />
           </section>
 
@@ -351,6 +392,21 @@ const boardRemoved = async () => {
         @update:open="editorOpen = $event"
       />
 
+      <!-- One dialog per seat, opened from the row it belongs to. Outside the band and the
+           identity for the reason the board's own is: a seat saved re-reads the board, and
+           the dialog must not be unmounted by the board it just changed arriving. -->
+      <seat-dialog
+        v-if="mayEdit"
+        v-model:open="seatOpen"
+        :accent="accent"
+        :board-end="shown?.endDate"
+        :board-id="shown?.id ?? null"
+        :board-start="shown?.startDate"
+        :seat="editingSeat"
+        @removed="seatSaved"
+        @saved="seatSaved"
+      />
+
       <call-band v-bind="BOARD_CALL" />
     </island>
   </v-main>
diff --git a/services/frontend/tests/e2e/board-seat-edit.spec.ts b/services/frontend/tests/e2e/board-seat-edit.spec.ts
new file mode 100644
index 000000000..413a9754c
--- /dev/null
+++ b/services/frontend/tests/e2e/board-seat-edit.spec.ts
@@ -0,0 +1,384 @@
+import {Buffer} from "node:buffer"
+import type {Page} from "@playwright/test"
+import {expect, test} from "./test"
+import {installApiMocks, loginAsBoard} from "./mocks"
+
+/** A portrait as the api answers with one, at the widths one is stored at. */
+const portrait = (name: string) => ({
+  path: `board-portraits/${name}.webp`,
+  url: `/files/public/board-portraits/${name}.webp`,
+  width: 640,
+  height: 960,
+  renditions: [160, 320, 640].map((width) => ({
+    url: `/files/public/board-portraits/${name}-${width}.webp`,
+    width,
+  })),
+})
+
+/**
+ * The history a spec writes to, made fresh for each one.
+ *
+ * A function rather than a constant: a seat written down lands on the board it belongs to, so a
+ * fixture shared between tests would carry one test's seat into the next.
+ */
+const history = () => [
+  {
+    id: 9, number: 9, name: "Eeveelutions", candidate: "Eeveelutions",
+    cheer: "RNG, Be With Me!", accent: null, description: null,
+    startDate: "2025-09-01", endDate: null, image: null, photo: null, version: 0,
+    createdAt: "2026-01-01T00:00:00Z", updatedAt: "2026-01-01T00:00:00Z",
+    members: [
+      {
+        id: 91, boardId: 9, userId: 1, role: "Chair", name: "Emma Dokter", nickname: "Emmz",
+        description: "Chairing the ninth board.", image: null, portrait: portrait("emma"),
+        startDate: "2025-09-01", endDate: "2026-08-31", version: 0,
+        createdAt: "2026-01-01T00:00:00Z", updatedAt: "2026-01-01T00:00:00Z",
+      },
+      {
+        id: 92, boardId: 9, userId: null, role: "Treasurer", name: "Viktor Petrov",
+        nickname: null, description: null, image: null, portrait: null,
+        startDate: "2025-09-01", endDate: "2026-08-31", version: 0,
+        createdAt: "2026-01-01T00:00:00Z", updatedAt: "2026-01-01T00:00:00Z",
+      },
+    ],
+  },
+  {
+    id: 4, number: 4, name: null, candidate: "Board 4", cheer: null, accent: null,
+    description: null, startDate: "2020-09-01", endDate: "2021-08-31",
+    image: null, photo: null, version: 0,
+    createdAt: "2026-01-01T00:00:00Z", updatedAt: "2026-01-01T00:00:00Z",
+    // A board nobody has been recorded on, which is where a seat is added from nothing.
+    members: [],
+  },
+]
+
+/**
+ * What a person does: bring the pointer to the row, then take up the pencil it reveals. On a
+ * touch screen the hover is a no-op and the pencil is already standing.
+ */
+const openSeat = async (page: Page, id: number) => {
+  await page.getByTestId(`board-seat-${id}`).hover()
+  await page.getByTestId(`board-seat-edit-${id}`).click()
+}
+
+/** The page as a board member reads it, opened on the board in office. */
+const asBoard = async (page: Page) => {
+  await loginAsBoard(page.context())
+  await installApiMocks(page, {boards: history()})
+  await page.goto("/board")
+  await expect(page.getByTestId("board-name")).toHaveText("Eeveelutions")
+}
+
+test.describe("a seat filled in on the page", () => {
+  test("offers a visitor no pencil and no way to add a seat", async ({page}) => {
+    await installApiMocks(page, {boards: history()})
+
+    await page.goto("/board")
+    await expect(page.getByTestId("board-seat-name-91")).toBeVisible()
+
+    // Absent rather than hidden: the page a visitor reads is not covered in pencils, and the
+    // history is what it shows.
+    await expect(page.getByTestId("board-seat-edit-91")).toHaveCount(0)
+    await expect(page.getByTestId("board-seat-add")).toHaveCount(0)
+    await expect(page.getByTestId("seat-dialog")).toHaveCount(0)
+  })
+
+  test("adds a seat to a board, in the board's own words for the role", async ({page}) => {
+    await asBoard(page)
+
+    await page.getByTestId("board-seat-add").click()
+    await expect(page.getByTestId("seat-dialog")).toBeVisible()
+
+    await page.getByTestId("seat-dialog-name").fill("Roos Kruk")
+    await page.getByTestId("seat-dialog-nickname").fill("SkyeWolf")
+    // Not from a fixed list: nine years of boards have renamed and combined their offices.
+    await page.getByTestId("seat-dialog-role")
+      .fill("Secretary and Commissioner of the Esports Lounge")
+    await page.getByTestId("seat-dialog-description").fill("Ran the lounge.")
+
+    // The save navigates nothing, so the request is what is awaited and the row is the proof.
+    const written = page.waitForRequest(
+      (request) => request.method() === "POST"
+        && /\/boards\/9\/members$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-dialog-save").click()
+    const body = JSON.parse((await written).postData() ?? "{}") as Record<string, unknown>
+
+    expect(body.displayName).toBe("Roos Kruk")
+    // Recorded apart from the name rather than typed into the middle of it.
+    expect(body.nickname).toBe("SkyeWolf")
+    expect(body.role).toBe("Secretary and Commissioner of the Esports Lounge")
+    expect(body.description).toBe("Ran the lounge.")
+
+    await expect(page.getByTestId("seat-dialog")).toHaveCount(0)
+    // And the page reads again, so the seat is on it: the name with the nickname back inside.
+    await expect(page.getByTestId("board-seat-name-901")).toHaveText('Roos "SkyeWolf" Kruk')
+    await expect(page.getByTestId("board-seat-role-901"))
+      .toHaveText("Secretary and Commissioner of the Esports Lounge")
+    await expect(page.getByTestId("board-seat-blurb-901")).toContainText("Ran the lounge.")
+  })
+
+  test("seats somebody on a board that had nobody at all", async ({page}) => {
+    await asBoard(page)
+
+    // The fourth board has no seats, and the way in is still at the end of the stack. Reached
+    // by its own address rather than off the strip: a phone's strip pans rather than scrolls.
+    await page.goto("/board?board=4")
+    await expect(page.getByTestId("board-no-seats")).toBeVisible()
+
+    await page.getByTestId("board-seat-add").click()
+    await page.getByTestId("seat-dialog-name").fill("Anne Schrader")
+    await page.getByTestId("seat-dialog-role").fill("Chairman")
+    await page.getByTestId("seat-dialog-save").click()
+
+    await expect(page.getByTestId("board-seat-name-901")).toHaveText("Anne Schrader")
+    await expect(page.getByTestId("board-no-seats")).toHaveCount(0)
+  })
+
+  test("opens a seat on what it says, and corrects it", async ({page}) => {
+    await asBoard(page)
+
+    await openSeat(page, 91)
+
+    // Everything the page read, back in the fields it was written in.
+    await expect(page.getByTestId("seat-dialog-name")).toHaveValue("Emma Dokter")
+    await expect(page.getByTestId("seat-dialog-nickname")).toHaveValue("Emmz")
+    await expect(page.getByTestId("seat-dialog-role")).toHaveValue("Chair")
+    await expect(page.getByTestId("seat-dialog-description"))
+      .toHaveValue("Chairing the ninth board.")
+    // The nickname sits beside the name rather than inside it, and the dialog says how the
+    // page will publish the two together.
+    await expect(page.getByTestId("seat-dialog-published"))
+      .toHaveText('Reads as Emma "Emmz" Dokter')
+
+    await page.getByTestId("seat-dialog-nickname").fill("LyndisLuna")
+    await page.getByTestId("seat-dialog-description").fill("Chaired the year of the rebuild.")
+
+    const written = page.waitForRequest(
+      (request) => request.method() === "PUT"
+        && /\/boards\/9\/members\/91$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-dialog-save").click()
+    const body = JSON.parse((await written).postData() ?? "{}") as Record<string, unknown>
+
+    expect(body.nickname).toBe("LyndisLuna")
+    expect(body.displayName).toBe("Emma Dokter")
+    expect(body.description).toBe("Chaired the year of the rebuild.")
+
+    await expect(page.getByTestId("board-seat-name-91")).toHaveText('Emma "LyndisLuna" Dokter')
+    await expect(page.getByTestId("board-seat-blurb-91"))
+      .toContainText("Chaired the year of the rebuild.")
+  })
+
+  test("uploads a portrait, shows it before the save, and puts it on the seat", async ({page}) => {
+    await asBoard(page)
+
+    // The seat with no portrait: the row draws its initials until one is uploaded.
+    await expect(page.getByTestId("board-seat-monogram-92")).toBeVisible()
+    await openSeat(page, 92)
+
+    await expect(page.getByTestId("seat-dialog-portrait-empty")).toBeAttached()
+    await page.getByTestId("seat-dialog-portrait-file").setInputFiles({
+      name: "viktor.png",
+      mimeType: "image/png",
+      buffer: Buffer.from(
+        "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8DwHwAFAAH/q842iQAAAABJRU5ErkJggg==",
+        "base64",
+      ),
+    })
+
+    // Shown before it is saved, because a picture nobody can see is one nobody can tell is wrong.
+    const preview = page.getByTestId("seat-dialog-portrait-preview")
+    await expect(preview).toBeVisible()
+    await expect(preview).toHaveAttribute("src", /mock-\d+\.webp$/)
+
+    const written = page.waitForRequest(
+      (request) => request.method() === "PUT"
+        && /\/boards\/9\/members\/92$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-dialog-save").click()
+    const body = JSON.parse((await written).postData() ?? "{}") as Record<string, unknown>
+
+    // The save names where the bytes are stored rather than carrying them.
+    expect(String(body.portrait)).toMatch(/mock-\d+\.webp$/)
+
+    // And the plate is a portrait now rather than a monogram.
+    await expect(page.getByTestId("board-seat-portrait-92")).toBeVisible()
+    await expect(page.getByTestId("board-seat-monogram-92")).toHaveCount(0)
+  })
+
+  test("links a seat to an account with the island's own picker", async ({page}) => {
+    await asBoard(page)
+
+    await openSeat(page, 92)
+    // Nothing attached: most people who have sat on a board never had an account here.
+    await expect(page.getByTestId("seat-dialog-attached")).toHaveCount(0)
+
+    // The island's picker rather than Vuetify's, so the search is a plain field and the list
+    // is drawn at the end of the document.
+    await page.getByTestId("seat-dialog-member-search").fill("Viktor")
+    await page.getByTestId("seat-dialog-member-2").click()
+    await expect(page.getByTestId("seat-dialog-attached")).toContainText("Viktor Petrov")
+
+    const linked = page.waitForRequest(
+      (request) => request.method() === "PUT"
+        && /\/boards\/9\/members\/92\/member$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-dialog-save").click()
+    const body = JSON.parse((await linked).postData() ?? "{}") as Record<string, unknown>
+
+    expect(body.userId).toBe(2)
+  })
+
+  test("detaches an account and leaves the seat standing under its own name", async ({page}) => {
+    await asBoard(page)
+
+    await openSeat(page, 91)
+    await expect(page.getByTestId("seat-dialog-attached")).toContainText("Emma Dokter")
+
+    await page.getByTestId("seat-dialog-detach").click()
+    await expect(page.getByTestId("seat-dialog-attached")).toHaveCount(0)
+    // The name is the seat's own, so detaching leaves it in the field it was in.
+    await expect(page.getByTestId("seat-dialog-name")).toHaveValue("Emma Dokter")
+
+    const detached = page.waitForRequest(
+      (request) => request.method() === "PUT"
+        && /\/boards\/9\/members\/91\/member$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-dialog-save").click()
+    const body = JSON.parse((await detached).postData() ?? "{}") as Record<string, unknown>
+
+    // A null member detaches, and the seat is still on the page under its own name.
+    expect(body.userId).toBeUndefined()
+    await expect(page.getByTestId("board-seat-name-91")).toHaveText('Emma "Emmz" Dokter')
+  })
+
+  test("pre-fills a new seat from the board's term, and records a handover part-way", async ({page}) => {
+    await asBoard(page)
+
+    await page.getByTestId("board-seat-add").click()
+    // The common case needs no typing: the board took office in the autumn of 2025 and is
+    // still in office, so the seat opens on the same stretch.
+    await expect(page.getByTestId("seat-dialog-start")).toHaveValue("2025-09-01")
+    await expect(page.getByTestId("seat-dialog-end")).toHaveValue("")
+
+    await page.getByTestId("seat-dialog-name").fill("Sylwia Nowak")
+    await page.getByTestId("seat-dialog-role").fill("Treasurer")
+    // A handover part-way through the year, recorded truthfully rather than as a full one.
+    await page.getByTestId("seat-dialog-start").fill("2026-02-01")
+
+    const written = page.waitForRequest(
+      (request) => request.method() === "POST"
+        && /\/boards\/9\/members$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-dialog-save").click()
+    const body = JSON.parse((await written).postData() ?? "{}") as Record<string, unknown>
+
+    // What the cohort module reads to answer "was on the board that year".
+    expect(body.startDate).toBe("2026-02-01")
+  })
+
+  test("carries a seat's own dates into the dialog rather than the board's", async ({page}) => {
+    await asBoard(page)
+
+    await openSeat(page, 91)
+
+    await expect(page.getByTestId("seat-dialog-start")).toHaveValue("2025-09-01")
+    await expect(page.getByTestId("seat-dialog-end")).toHaveValue("2026-08-31")
+  })
+
+  test("asks before a seat is removed, and names what will go", async ({page}) => {
+    await asBoard(page)
+
+    await openSeat(page, 91)
+    await page.getByTestId("seat-dialog-remove").click()
+
+    // Named, so the question can be answered without remembering what was clicked. A blurb is
+    // somebody's own words about themselves, so the question says it goes.
+    const question = page.getByTestId("seat-remove-dialog").getByTestId("confirm-question")
+    await expect(question).toContainText('Emma "Emmz" Dokter')
+    await expect(question).toContainText("Chair")
+    await expect(question).toContainText("What they wrote about themselves goes with it.")
+
+    const dropped = page.waitForRequest(
+      (request) => request.method() === "DELETE"
+        && /\/boards\/9\/members\/91$/.test(new URL(request.url()).pathname),
+    )
+    await page.getByTestId("seat-remove-dialog").getByTestId("confirm-go").click()
+    await dropped
+
+    await expect(page.getByTestId("board-seat-91")).toHaveCount(0)
+    // The seat beside it is untouched.
+    await expect(page.getByTestId("board-seat-name-92")).toHaveText("Viktor Petrov")
+  })
+
+  test("keeps the seat where a removal is declined", async ({page}) => {
+    await asBoard(page)
+
+    await openSeat(page, 91)
+    await page.getByTestId("seat-dialog-remove").click()
+    await page.getByTestId("seat-remove-dialog").getByTestId("confirm-cancel").click()
+
+    await expect(page.getByTestId("board-seat-name-91")).toHaveText('Emma "Emmz" Dokter')
+  })
+
+  test("leaves a seat exactly as it was when the dialog is cancelled, picture and all", async ({page}) => {
+    await asBoard(page)
+
+    const plate = page.getByTestId("board-seat-portrait-91")
+    const before = await plate.getAttribute("src")
+
+    await openSeat(page, 91)
+    await page.getByTestId("seat-dialog-name").fill("Somebody Else")
+    await page.getByTestId("seat-dialog-nickname").fill("Wrong")
+    await page.getByTestId("seat-dialog-role").fill("Nobody")
+    // A picture is stored on choosing and reaches the seat only on the save, so cancelling
+    // leaves the seat on the portrait it had.
+    await page.getByTestId("seat-dialog-portrait-file").setInputFiles({
+      name: "wrong.png",
+      mimeType: "image/png",
+      buffer: Buffer.from(
+        "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8DwHwAFAAH/q842iQAAAABJRU5ErkJggg==",
+        "base64",
+      ),
+    })
+    await expect(page.getByTestId("seat-dialog-portrait-preview")).toHaveAttribute("src", /mock-/)
+
+    await page.getByTestId("seat-dialog-cancel").click()
+    await expect(page.getByTestId("seat-dialog")).toHaveCount(0)
+
+    await expect(page.getByTestId("board-seat-name-91")).toHaveText('Emma "Emmz" Dokter')
+    await expect(page.getByTestId("board-seat-role-91")).toHaveText("Chair")
+    await expect(plate).toHaveAttribute("src", before ?? "")
+
+    // And reopening it shows the seat as it stands rather than what was typed and abandoned.
+    await openSeat(page, 91)
+    await expect(page.getByTestId("seat-dialog-name")).toHaveValue("Emma Dokter")
+    await expect(page.getByTestId("seat-dialog-role")).toHaveValue("Chair")
+  })
+
+  test("says why a save was refused, and keeps what was typed", async ({page}) => {
+    await asBoard(page)
+
+    // The sdk hands a refusal back as a body rather than throwing, so a dialog that only read
+    // `data` would close on a save that never happened.
+    await page.route("**/boards/9/members/91", async (route) => {
+      if (route.request().method() !== "PUT") return route.fallback()
+      await route.fulfill({
+        status: 400,
+        contentType: "application/json",
+        body: JSON.stringify({detail: "A seat cannot end before it began."}),
+      })
+    })
+
+    await openSeat(page, 91)
+    await page.getByTestId("seat-dialog-end").fill("2024-01-01")
+    await page.getByTestId("seat-dialog-save").click()
+
+    await expect(page.getByTestId("seat-dialog-failure"))
+      .toHaveText("A seat cannot end before it began.")
+    // Still open, and still holding what was typed: the objection is something to act on.
+    await expect(page.getByTestId("seat-dialog-end")).toHaveValue("2024-01-01")
+    await expect(page.getByTestId("seat-dialog-name")).toHaveValue("Emma Dokter")
+  })
+})
diff --git a/services/frontend/tests/e2e/mocks.ts b/services/frontend/tests/e2e/mocks.ts
index ad9f669cb..fa4e0a8fe 100644
--- a/services/frontend/tests/e2e/mocks.ts
+++ b/services/frontend/tests/e2e/mocks.ts
@@ -313,6 +313,8 @@ export async function installApiMocks(page: Page, fixtures: Fixtures = {}) {
   const icons = new Map<number, MockImage>()
   const stored = new Map<string, MockImage>()
   let nextFileId = 500
+  /** Seats written down during a test, each taking the next id the way the api would. */
+  let nextSeatId = 900
   /**
    * An image as the api describes one. The size is that of the picture actually served below,
    * so a page reserving an image's space reserves the right amount of it.
@@ -1025,13 +1027,96 @@ export async function installApiMocks(page: Page, fixtures: Fixtures = {}) {
       boardsGone.add(id)
       return route.fulfill({status: 204, body: ""})
     }
+    /*
+     * A seat written down, corrected, linked or removed lands on the board it belongs to, so a
+     * page that reads again is answered the way the api would rather than told the board never
+     * changed. Held on the fixture's own `members` rather than beside it, because that is the
+     * one list every read of a board goes through.
+     *
+     * A fixture a spec shares between tests would carry a write into the next one, so a spec
+     * that writes hands `installApiMocks` boards of its own making.
+     *
+     * The boards themselves rather than `boardsNow()`, which composes a copy per board: a seat
+     * pushed onto a copy's `members` would reach the board it belongs to and a seat removed
+     * from one would not, because a removal replaces the list rather than adding to it.
+     */
+    const boardHolding = (boardId: number): Record<string, unknown> | undefined =>
+      [...(fixtures.boards ?? boardFixtures), ...boardsMade]
+        .find((b) => Number(b.id) === boardId)
+
+    const seatsOf = (board: Record<string, unknown>): Array<Record<string, unknown>> => {
+      if (!Array.isArray(board.members)) board.members = []
+      return board.members as Array<Record<string, unknown>>
+    }
+
+    /**
+     * A seat as the api answers with one after a write.
+     *
+     * Every field the write carries is replaced the way the api's own does, so a field the save
+     * left out is cleared rather than kept. The save named where its portrait is stored and the
+     * answer carries the picture itself; naming none clears the portrait. The name arrives as
+     * `displayName` and is answered as `name`, which is the api's own asymmetry.
+     */
+    const seatWritten = (
+      base: Record<string, unknown>,
+      body: Record<string, unknown>,
+    ): Record<string, unknown> => ({
+      ...base,
+      role: body.role,
+      name: body.displayName ?? null,
+      nickname: body.nickname ?? null,
+      description: body.description ?? null,
+      image: body.image ?? null,
+      portrait: pictureNamed(body.portrait),
+      startDate: body.startDate,
+      endDate: body.endDate ?? null,
+      updatedAt: "2026-01-02T00:00:00Z",
+    })
+
     if (method === "POST" && /^\/boards\/\d+\/members$/.test(path)) {
+      const boardId = Number(path.split("/")[2])
       const body = JSON.parse(request.postData() ?? "{}") as Record<string, unknown>
-      return fulfillJson(route, {id: 99, boardId: Number(path.split("/")[2]), userId: body.userId ?? null, role: body.role, name: body.displayName ?? null, nickname: body.nickname ?? null, description: body.description ?? null, image: body.image ?? null, startDate: body.startDate, endDate: body.endDate ?? null, version: 0, createdAt: "2026-01-01T00:00:00Z", updatedAt: "2026-01-01T00:00:00Z"}, 201)
+      nextSeatId += 1
+      const made = seatWritten({
+        id: nextSeatId,
+        boardId,
+        userId: body.userId ?? null,
+        version: 0,
+        createdAt: "2026-01-02T00:00:00Z",
+      }, body)
+      const board = boardHolding(boardId)
+      if (board) seatsOf(board).push(made)
+      return fulfillJson(route, made, 201)
     }
+    if (method === "PUT" && /^\/boards\/\d+\/members\/\d+$/.test(path)) {
+      const boardId = Number(path.split("/")[2])
+      const id = Number(path.split("/")[4])
+      const body = JSON.parse(request.postData() ?? "{}") as Record<string, unknown>
+      const seats = seatsOf(boardHolding(boardId) ?? {})
+      const at = seats.findIndex((one) => Number(one.id) === id)
+      if (at === -1) return fulfillJson(route, {detail: "No such seat."}, 404)
+      const saved = {...seatWritten(seats[at]!, body), version: 1}
+      seats[at] = saved
+      return fulfillJson(route, saved)
+    }
+    // A null member detaches the seat, which keeps standing under its own name.
     if (method === "PUT" && /^\/boards\/\d+\/members\/\d+\/member$/.test(path)) {
+      const boardId = Number(path.split("/")[2])
+      const id = Number(path.split("/")[4])
       const body = JSON.parse(request.postData() ?? "{}") as Record<string, unknown>
-      return fulfillJson(route, {id: 92, boardId: 9, userId: body.userId ?? null, role: "Secretary", name: "Viktor Petrov", description: null, image: null, startDate: "2025-09-01", endDate: "2026-08-31", version: 1, createdAt: "2026-01-01T00:00:00Z", updatedAt: "2026-01-01T00:00:00Z"})
+      const seats = seatsOf(boardHolding(boardId) ?? {})
+      const at = seats.findIndex((one) => Number(one.id) === id)
+      if (at === -1) return fulfillJson(route, {detail: "No such seat."}, 404)
+      const linked = {...seats[at]!, userId: body.userId ?? null, version: 1}
+      seats[at] = linked
+      return fulfillJson(route, linked)
+    }
+    if (method === "DELETE" && /^\/boards\/\d+\/members\/\d+$/.test(path)) {
+      const boardId = Number(path.split("/")[2])
+      const id = Number(path.split("/")[4])
+      const board = boardHolding(boardId)
+      if (board) board.members = seatsOf(board).filter((one) => Number(one.id) !== id)
+      return route.fulfill({status: 204, body: ""})
     }
     // A game added during a test is one of the games from then on, the way the api has it.
     if (method === "POST" && path === "/esports/games") {
diff --git a/services/frontend/tests/unit/components/island/SeatRows.test.ts b/services/frontend/tests/unit/components/island/SeatRows.test.ts
index 75dad7b60..1dcc849fc 100644
--- a/services/frontend/tests/unit/components/island/SeatRows.test.ts
+++ b/services/frontend/tests/unit/components/island/SeatRows.test.ts
@@ -14,7 +14,7 @@ const rows = [
   {id: 93, name: "Roos Kruk", role: "Commissioner of Internal Affairs"},
 ]
 
-const mountRows = (over: Partial<{rows: typeof rows}> = {}) =>
+const mountRows = (over: Partial<{rows: typeof rows; mayEdit: boolean; addLabel: string}> = {}) =>
   mount(SeatRows, {props: {rows, accent: "#3387fa", testidPrefix: "board", ...over}})
 
 const row = (wrapper: ReturnType<typeof mountRows>, id: number) =>
@@ -115,4 +115,42 @@ describe("SeatRows", () => {
     expect(row(wrapper, 71).classes()).toContain("seat-row--open")
     expect(row(wrapper, 72).classes()).not.toContain("seat-row--open")
   })
+
+  it("offers a visitor no pencil and no way to add a seat", () => {
+    const wrapper = mountRows()
+
+    // Not hidden: absent. An affordance nobody may take up is not drawn at all.
+    expect(wrapper.find('[data-testid="board-seat-edit-91"]').exists()).toBe(false)
+    expect(wrapper.find('[data-testid="board-seat-add"]').exists()).toBe(false)
+  })
+
+  it("offers a pencil on every row, named for the seat it opens", () => {
+    const wrapper = mountRows({mayEdit: true})
+
+    // Every row, including the one with nothing written about it, which offers no chevron.
+    expect(wrapper.get('[data-testid="board-seat-edit-91"]').attributes("aria-label"))
+      .toBe('Edit Emma "Emmz" Dokter')
+    expect(wrapper.get('[data-testid="board-seat-edit-93"]').attributes("aria-label"))
+      .toBe("Edit Roos Kruk")
+  })
+
+  it("reports which seat a pencil was pressed on", async () => {
+    const wrapper = mountRows({mayEdit: true})
+
+    await wrapper.get('[data-testid="board-seat-edit-92"]').trigger("click")
+
+    expect(wrapper.emitted("edit")).toStrictEqual([[92]])
+    // The row itself is not opened by the press: the pencil is a different act from reading.
+    expect(wrapper.emitted("add")).toBeUndefined()
+  })
+
+  it("offers one way in at the end of the stack, in the words the page chose", async () => {
+    const wrapper = mountRows({mayEdit: true, addLabel: "Add a seat"})
+
+    const add = wrapper.get('[data-testid="board-seat-add"]')
+    expect(add.text()).toBe("Add a seat")
+    await add.trigger("click")
+
+    expect(wrapper.emitted("add")).toHaveLength(1)
+  })
 })