diff --git a/backend/src/routes/sponsorDocs.ts b/backend/src/routes/sponsorDocs.ts
index 25fe66b9..33460013 100644
--- a/backend/src/routes/sponsorDocs.ts
+++ b/backend/src/routes/sponsorDocs.ts
@@ -1,5 +1,6 @@
 import { guestPortalSlots, recordGuestPortalTimeChoice } from '../events/guestIntakePortal';
 import { hydrateGuestEventSlotOptions } from '../sponsorDocs/templates';
+import { recordPortalDocEdit } from '../sponsorDocs/portalEditTask';
 import { projectDocumentEvent, readDocumentEventMetadata } from '../sponsorDocs/eventMetadata';
 import { randomUUID } from 'node:crypto';
 import type { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';
@@ -1026,6 +1027,10 @@ export async function handleSponsorDocRoutes(
           status: body.status as SponsorDocStatus | undefined,
           actorKind: 'sponsor',
         });
+        if (updated) {
+          const docUrl = `${sponsorDocPortalBaseUrl(event)}${sponsorDocPathForTemplate(updated.template)}/${encodeURIComponent(updated.id)}`;
+          await recordPortalDocEdit(client, { before: verified.doc, after: updated, docUrl });
+        }
         try { if (updated && body.timeChoiceIntent !== undefined) await recordGuestPortalTimeChoice(client, updated, body.timeChoiceIntent); }
         catch (error) { return json(422, { error: (error as Error).message, code: 'guest_time_choice_pending' }); }
         return json(200, {
diff --git a/backend/src/sponsorDocs/portalEditTask.ts b/backend/src/sponsorDocs/portalEditTask.ts
new file mode 100644
index 00000000..59ad07e8
--- /dev/null
+++ b/backend/src/sponsorDocs/portalEditTask.ts
@@ -0,0 +1,121 @@
+import { randomUUID } from 'node:crypto';
+import type { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';
+import { getCardConsistent } from '../db/cards';
+import {
+  createTask,
+  getTaskConsistent,
+  listTasksByCardConsistent,
+  listTasksByStatus,
+  TaskVersionConflictError,
+  updateTask,
+} from '../db/tasks';
+import { resolveDefaultAssigneeId } from '../db/workspaceSettings';
+import type { SponsorDoc } from '../db/sponsorDocs';
+import type { Task } from '../types';
+import { getSponsorDocTemplate } from './templates';
+
+export const PORTAL_EDIT_TASK_SOURCE = 'portal-doc-edit';
+const ACTOR = 'system:portal-doc-edit';
+const VALUE_EXCERPT = 160;
+const OPEN_STATUSES = ['todo', 'waiting'];
+
+export interface PortalDocChange {
+  field: string;
+  before: string;
+  after: string;
+}
+
+function excerpt(value: unknown): string {
+  const text = String(value ?? '').replace(/\s+/g, ' ').trim();
+  return text.length > VALUE_EXCERPT ? `${text.slice(0, VALUE_EXCERPT - 1)}…` : text;
+}
+
+/** Content fields and status that differ between two versions of one doc. */
+export function diffPortalDoc(before: SponsorDoc, after: SponsorDoc): PortalDocChange[] {
+  const changes: PortalDocChange[] = [];
+  const keys = new Set([...Object.keys(before.content), ...Object.keys(after.content)]);
+  for (const key of keys) {
+    const was = String(before.content[key] ?? '');
+    const now = String(after.content[key] ?? '');
+    if (was !== now) changes.push({ field: key, before: excerpt(was), after: excerpt(now) });
+  }
+  if (before.status !== after.status) changes.push({ field: 'status', before: before.status, after: after.status });
+  return changes;
+}
+
+function describeChanges(changes: PortalDocChange[]): string {
+  return changes
+    .map((change) => `- ${change.field}: ${change.before ? `"${change.before}"` : '(empty)'} → ${change.after ? `"${change.after}"` : '(empty)'}`)
+    .join('\n');
+}
+
+async function findOpenTask(client: DynamoDBDocumentClient, docId: string, cardId: string | null): Promise<Task | null> {
+  const tag = `doc:${docId}`;
+  const candidates = cardId
+    ? await listTasksByCardConsistent(client, cardId)
+    : (await Promise.all(OPEN_STATUSES.map((status) => listTasksByStatus(client, status)))).flat();
+  return candidates.find((task) =>
+    task.source === PORTAL_EDIT_TASK_SOURCE
+    && OPEN_STATUSES.includes(task.status)
+    && (task.tags || []).includes(tag)) || null;
+}
+
+/**
+ * Surface an external (guest or sponsor) edit to a shared portal doc as one
+ * open Task for the default owner team. A burst of edits appends to the open
+ * Task; a new Task appears only once the previous one is closed.
+ */
+export async function recordPortalDocEdit(
+  client: DynamoDBDocumentClient,
+  input: { before: SponsorDoc; after: SponsorDoc; docUrl: string },
+): Promise<Task | null> {
+  const { before, after, docUrl } = input;
+  const changes = diffPortalDoc(before, after);
+  if (changes.length === 0) return null;
+
+  const card = await getCardConsistent(client, after.cardId);
+  const activeCardId = card && card.status === 'active' ? card.id : null;
+  const label = getSponsorDocTemplate(after.template).shortLabel;
+  const cardTitle = card?.title || after.title;
+  const now = new Date().toISOString();
+  const noteText = `${after.lastEditedByName || 'External editor'} edited ${label} "${after.title}" (${docUrl}):\n${describeChanges(changes)}`;
+
+  for (let attempt = 0; attempt < 3; attempt += 1) {
+    const open = await findOpenTask(client, after.id, activeCardId);
+    if (!open) break;
+    try {
+      return await updateTask(client, open.id, {
+        currentTask: open,
+        expectedVersion: open.version,
+        patch: {
+          comment: noteText,
+          notesLog: [...(open.notesLog || []), { id: randomUUID(), text: noteText, authorId: ACTOR, createdAt: now }],
+        },
+        historyEvents: [{
+          id: randomUUID(), taskId: open.id, ...(activeCardId ? { cardId: activeCardId } : {}),
+          action: 'noted', actorId: ACTOR, note: noteText, createdAt: now,
+        }],
+        actorId: ACTOR,
+        triggerKind: 'portal-doc-edit',
+      });
+    } catch (error) {
+      if (!(error instanceof TaskVersionConflictError)) throw error;
+      const stillThere = await getTaskConsistent(client, open.id);
+      if (!stillThere || !OPEN_STATUSES.includes(stillThere.status)) break;
+    }
+  }
+
+  const assigneeId = await resolveDefaultAssigneeId(client);
+  return createTask(client, {
+    description: `Review portal doc edit: ${label} "${after.title}" (${cardTitle}${activeCardId ? '' : `, card ${after.cardId}`})`,
+    date: now.slice(0, 10),
+    status: 'todo',
+    source: PORTAL_EDIT_TASK_SOURCE,
+    tags: ['portal-edit', `doc:${after.id}`, `card:${after.cardId}`],
+    link: docUrl,
+    comment: noteText,
+    notesLog: [{ id: randomUUID(), text: noteText, authorId: ACTOR, createdAt: now }],
+    ...(assigneeId ? { assigneeId } : {}),
+    ...(activeCardId ? { cardId: activeCardId } : {}),
+  });
+}
diff --git a/backend/tests/portal-doc-edit-task.test.ts b/backend/tests/portal-doc-edit-task.test.ts
new file mode 100644
index 00000000..18f254c2
--- /dev/null
+++ b/backend/tests/portal-doc-edit-task.test.ts
@@ -0,0 +1,155 @@
+import { describe, it, before, after } from 'node:test';
+import assert from 'node:assert';
+import type { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';
+import { getClient } from '../src/db/client';
+import { createTables, startLocal, stopLocal } from '../scripts/local-dynamodb';
+import { createCard } from '../src/db/cards';
+import { createTask, getTaskConsistent, listTasksByCardConsistent, listTasksByStatus, updateTask } from '../src/db/tasks';
+import { createUser } from '../src/db/users';
+import { createSession } from '../src/db/sessions';
+import { createPodcastEpisode } from '../src/db/podcastEpisodes';
+import { getWorkspaceSettings, setDefaultAssignee } from '../src/db/workspaceSettings';
+import { PORTAL_EDIT_TASK_SOURCE } from '../src/sponsorDocs/portalEditTask';
+import { templateLink } from './helpers/cardTemplate';
+
+describe('portal doc edits create one open Task for the owner team', () => {
+  let client: DynamoDBDocumentClient;
+  let handler: typeof import('../src/handler').handler;
+  let staffUserId: string;
+  let staffToken: string;
+
+  before(async () => {
+    const port = await startLocal();
+    client = await getClient(port);
+    await createTables(client);
+    process.env.IS_LOCAL = 'true';
+    handler = (await import('../src/handler')).handler;
+    const user = await createUser(client, { email: 'orin@datatalks.club', name: 'Orin', passwordHash: 'unused', role: 'admin' });
+    staffUserId = user.id;
+    staffToken = (await createSession(client, staffUserId)).token;
+    const settings = await getWorkspaceSettings(client);
+    await setDefaultAssignee(client, { defaultAssigneeId: staffUserId, expectedVersion: settings.version });
+  });
+
+  after(async () => {
+    await stopLocal();
+    delete process.env.IS_LOCAL;
+  });
+
+  const staffReq = (method: string, path: string, body?: unknown) => handler({
+    httpMethod: method, path,
+    headers: { authorization: `Bearer ${staffToken}`, 'x-user-id': staffUserId, host: 'ops.dtcdev.click', 'x-forwarded-proto': 'https' },
+    queryStringParameters: null, body: body === undefined ? null : JSON.stringify(body),
+  }, {});
+
+  const externalPut = (docId: string, code: string, content: Record<string, string>, status?: string) => handler({
+    httpMethod: 'PUT', path: `/api/sponsor-docs/${docId}`,
+    headers: { host: 'ops.dtcdev.click', 'x-forwarded-proto': 'https', 'x-forwarded-for': '198.51.100.7', 'x-sponsor-doc-anonymous': 'true', 'x-sponsor-doc-code': code },
+    queryStringParameters: null, body: JSON.stringify({ content, ...(status ? { status } : {}) }),
+  }, {});
+
+  const portalTasks = async (cardId: string) =>
+    (await listTasksByCardConsistent(client, cardId)).filter((t) => t.source === PORTAL_EDIT_TASK_SOURCE);
+
+  async function close(taskId: string) {
+    const task = await getTaskConsistent(client, taskId);
+    await updateTask(client, taskId, { currentTask: task!, expectedVersion: task!.version, patch: { status: 'done', completedBy: staffUserId, completedAt: new Date().toISOString() } });
+  }
+
+  async function createDoc(cardId: string, template: string) {
+    const res = await staffReq('POST', '/api/sponsor-docs', { cardId, template, autoSendEmail: false });
+    assert.strictEqual(res.statusCode, 201, res.body);
+    return JSON.parse(res.body).doc as { id: string; accessCode: string; docUrl: string; content: Record<string, string> };
+  }
+
+  it('sponsor doc: burst of edits -> one open Task; edit after close -> new Task', async () => {
+    const card = await createCard(client, {
+      ...templateLink(), title: '[Newsletter] (02 NOV 2026) #310 - Acme', anchorDate: '2026-11-02', sponsor: 'Acme',
+      cardLinks: [{ name: 'Sponsorship document', url: '' }],
+    });
+    await createTask(client, { description: 'Prepare newsletter', date: '2026-11-02', cardId: card.id });
+    const doc = await createDoc(card.id, 'newsletter-main');
+    assert.strictEqual((await portalTasks(card.id)).length, 0, 'staff creation raises nothing');
+
+    assert.strictEqual((await externalPut(doc.id, doc.accessCode, { subjectLine: 'First subject' })).statusCode, 200);
+    let tasks = await portalTasks(card.id);
+    assert.strictEqual(tasks.length, 1);
+    assert.strictEqual(tasks[0].assigneeId, staffUserId);
+    assert.strictEqual(tasks[0].status, 'todo');
+    assert.strictEqual(tasks[0].link, doc.docUrl);
+    assert.ok(!tasks[0].link!.includes('code='), 'task link never carries the access code');
+    assert.match(tasks[0].description, /Acme/);
+    assert.match(tasks[0].comment!, /subjectLine: \(empty\) → "First subject"/);
+
+    // Same value again changes nothing -> no note, no task
+    await externalPut(doc.id, doc.accessCode, { subjectLine: 'First subject' });
+    // Burst
+    await externalPut(doc.id, doc.accessCode, { subjectLine: 'Second subject' });
+    await externalPut(doc.id, doc.accessCode, { previewText: 'Preview' });
+    tasks = await portalTasks(card.id);
+    assert.strictEqual(tasks.length, 1, 'burst stays on one open task');
+    const notes = tasks[0].notesLog!.map((n) => n.text);
+    assert.strictEqual(notes.length, 3);
+    assert.match(notes[1], /"First subject" → "Second subject"/);
+    assert.match(notes[2], /previewText/);
+
+    await close(tasks[0].id);
+    const third = await externalPut(doc.id, doc.accessCode, { subjectLine: 'Third subject' });
+    assert.strictEqual(third.statusCode, 200, third.body);
+    tasks = await portalTasks(card.id);
+    assert.strictEqual(tasks.length, 2, 'edit after close opens a new task');
+    assert.strictEqual(tasks.filter((t) => t.status === 'todo').length, 1);
+  });
+
+  it('staff edits do not raise a task', async () => {
+    const card = await createCard(client, { ...templateLink(), title: '[Newsletter] (09 NOV 2026) #311 - Globex', anchorDate: '2026-11-09', sponsor: 'Globex', cardLinks: [{ name: 'Sponsorship document', url: '' }] });
+    const doc = await createDoc(card.id, 'newsletter-main');
+    const res = await staffReq('PUT', `/api/sponsor-docs/${doc.id}`, { content: { subjectLine: 'Staff wording' } });
+    assert.strictEqual(res.statusCode, 200, res.body);
+    assert.strictEqual((await portalTasks(card.id)).length, 0);
+  });
+
+  it('guest doc (podcast episode brief): edits raise one task naming doc, card and fields', async () => {
+    const card = await createCard(client, { ...templateLink(), title: '[Podcast] 2026-12-01 - Jane Doe', anchorDate: '2026-12-01', people: ['Jane Doe'] });
+    await createPodcastEpisode(client, { title: 'Shipping ML features', guests: [{ name: 'Jane Doe' }], status: 'booked', recordingDate: '2026-12-01', cardId: card.id });
+    const doc = await createDoc(card.id, 'podcast-episode-brief');
+    const fieldKey = Object.keys(doc.content).find((key) => doc.content[key] === '' ) as string;
+    assert.ok(fieldKey, 'brief has an editable field');
+
+    assert.strictEqual((await externalPut(doc.id, doc.accessCode, { [fieldKey]: 'Guest wrote this' })).statusCode, 200);
+    await externalPut(doc.id, doc.accessCode, { [fieldKey]: 'Guest rewrote this' });
+    const tasks = await portalTasks(card.id);
+    assert.strictEqual(tasks.length, 1);
+    assert.strictEqual(tasks[0].cardId, card.id);
+    assert.match(tasks[0].description, /Jane Doe/);
+    assert.ok(tasks[0].tags!.includes(`doc:${doc.id}`));
+    assert.strictEqual(tasks[0].link, doc.docUrl);
+    assert.match(tasks[0].notesLog!.map((n) => n.text).join('\n'), new RegExp(`${fieldKey}: "Guest wrote this" → "Guest rewrote this"`));
+  });
+
+  it('different docs on one card keep separate tasks', async () => {
+    const card = await createCard(client, { ...templateLink(), title: '[Podcast] 2026-12-08 - Max Roe', anchorDate: '2026-12-08', people: ['Max Roe'] });
+    await createPodcastEpisode(client, { title: 'Data contracts', guests: [{ name: 'Max Roe' }], status: 'booked', recordingDate: '2026-12-08', cardId: card.id });
+    const a = await createDoc(card.id, 'podcast-episode-brief');
+    const b = await createDoc(card.id, 'podcast');
+    const key = (d: { content: Record<string, string> }) => Object.keys(d.content).find((k) => d.content[k] === '') as string;
+    await externalPut(a.id, a.accessCode, { [key(a)]: 'x' });
+    const resB = await externalPut(b.id, b.accessCode, { [key(b)]: 'y' });
+    assert.strictEqual(resB.statusCode, 200, resB.body);
+    assert.strictEqual((await portalTasks(card.id)).length, 2);
+  });
+
+  it('card archived since the last task closed: edit still opens a task naming the card', async () => {
+    const card = await createCard(client, { ...templateLink(), title: '[Newsletter] (16 NOV 2026) #312 - Initech', anchorDate: '2026-11-16', sponsor: 'Initech', cardLinks: [{ name: 'Sponsorship document', url: '' }] });
+    const only = await createTask(client, { description: 'Only task', date: '2026-11-16', cardId: card.id });
+    const doc = await createDoc(card.id, 'newsletter-main');
+    await close(only.id); // archives the card
+    assert.strictEqual((await externalPut(doc.id, doc.accessCode, { subjectLine: 'Late edit' })).statusCode, 200);
+    await externalPut(doc.id, doc.accessCode, { subjectLine: 'Later edit' });
+    const open = (await listTasksByStatus(client, 'todo')).filter((t) => t.source === PORTAL_EDIT_TASK_SOURCE && t.tags?.includes(`doc:${doc.id}`));
+    assert.strictEqual(open.length, 1, 'cardless dedupe finds the open task');
+    assert.ok(open[0].tags!.includes(`card:${card.id}`));
+    assert.match(open[0].description, /Initech/);
+    assert.strictEqual(open[0].notesLog!.length, 2);
+  });
+});