diff --git a/src/app/api/admin/backups/[id]/restore/__tests__/round-trip.test.ts b/src/app/api/admin/backups/[id]/restore/__tests__/round-trip.test.ts
index 9d6921831..41dcda179 100644
--- a/src/app/api/admin/backups/[id]/restore/__tests__/round-trip.test.ts
+++ b/src/app/api/admin/backups/[id]/restore/__tests__/round-trip.test.ts
@@ -296,6 +296,7 @@ function sourceClient() {
     // same reason as the visit tables above.
     measurementReminder: { findMany: vi.fn().mockResolvedValue([]) },
     measurementReminderEvent: { findMany: vi.fn().mockResolvedValue([]) },
+    coachConversation: { findMany: vi.fn().mockResolvedValue([]) },
     customMetric: {
       findMany: vi.fn().mockResolvedValue([
         {
diff --git a/src/app/api/admin/backups/[id]/restore/route.ts b/src/app/api/admin/backups/[id]/restore/route.ts
index 579e25967..89c64bf45 100644
--- a/src/app/api/admin/backups/[id]/restore/route.ts
+++ b/src/app/api/admin/backups/[id]/restore/route.ts
@@ -50,6 +50,7 @@ import { restoreIntradayProfileData } from "@/lib/export/intraday-profile-backup
 import { restoreHealthScoreData } from "@/lib/export/health-score-backup";
 import { restoreVisitsData } from "@/lib/export/visits-backup";
 import { restoreVaccinationsData } from "@/lib/export/vaccinations-backup";
+import { restoreCoachData } from "@/lib/export/coach-backup";
 import { restoreRemindersData } from "@/lib/export/reminders-backup";
 import { invalidateUserData } from "@/lib/cache/invalidate";
 
@@ -98,6 +99,9 @@ interface RestoreResponse {
     vaccinationLinks: number;
     measurementReminders: number;
     measurementReminderEvents: number;
+    coachConversations: number;
+    coachMessages: number;
+    coachConversationDocuments: number;
   };
 }
 
@@ -1413,6 +1417,22 @@ const handler = apiHandler(
             skips,
           );
 
+          // The Coach's threads, turns and document links. AFTER the
+          // documents on purpose: an attachment carries a `documentId` that
+          // is a foreign key against them, so running earlier would make
+          // every attachment unresolvable and drop the provenance that makes
+          // an old answer checkable. The id set is threaded in rather than
+          // re-queried so the function stays a pure reader of this
+          // transaction. Both ends of this section live in
+          // `src/lib/export/coach-backup.ts`.
+          const coachCleared = await restoreCoachData(
+            tx,
+            ownerId,
+            payload,
+            new Set(payload.documents.map((document) => document.id)),
+            skips,
+          );
+
           const cleared = {
             measurements: measurements.count,
             medications: meds.count,
@@ -1447,6 +1467,9 @@ const handler = apiHandler(
             measurementReminders: remindersCleared.measurementReminders,
             measurementReminderEvents:
               remindersCleared.measurementReminderEvents,
+            coachConversations: coachCleared.coachConversations,
+            coachMessages: coachCleared.coachMessages,
+            coachConversationDocuments: coachCleared.coachConversationDocuments,
           };
           return { cleared, skipped: summarizeRestoreSkips(skips) };
         },
diff --git a/src/app/api/export/__tests__/per-type-routes.test.ts b/src/app/api/export/__tests__/per-type-routes.test.ts
index dbd70b192..ee28c881b 100644
--- a/src/app/api/export/__tests__/per-type-routes.test.ts
+++ b/src/app/api/export/__tests__/per-type-routes.test.ts
@@ -42,6 +42,7 @@ vi.mock("@/lib/db", () => ({
     // same reason as the visit tables above.
     measurementReminder: { findMany: vi.fn().mockResolvedValue([]) },
     measurementReminderEvent: { findMany: vi.fn().mockResolvedValue([]) },
+    coachConversation: { findMany: vi.fn().mockResolvedValue([]) },
     // v1.15.0 — cycle tables read by the full-backup helper.
     cycleProfile: { findUnique: vi.fn() },
     menstrualCycle: { findMany: vi.fn() },
@@ -129,6 +130,7 @@ beforeEach(() => {
   vi.mocked(prisma.measurementReminderEvent.findMany).mockResolvedValue(
     [] as never,
   );
+  vi.mocked(prisma.coachConversation.findMany).mockResolvedValue([] as never);
 });
 
 afterEach(() => {
diff --git a/src/app/api/export/encrypted/__tests__/route.test.ts b/src/app/api/export/encrypted/__tests__/route.test.ts
index e124d475f..37ea2a345 100644
--- a/src/app/api/export/encrypted/__tests__/route.test.ts
+++ b/src/app/api/export/encrypted/__tests__/route.test.ts
@@ -40,6 +40,7 @@ vi.mock("@/lib/db", () => ({
     // same reason as the visit tables above.
     measurementReminder: { findMany: vi.fn().mockResolvedValue([]) },
     measurementReminderEvent: { findMany: vi.fn().mockResolvedValue([]) },
+    coachConversation: { findMany: vi.fn().mockResolvedValue([]) },
     cycleProfile: { findUnique: vi.fn().mockResolvedValue(null) },
     menstrualCycle: { findMany: vi.fn().mockResolvedValue([]) },
     cycleDayLog: { findMany: vi.fn().mockResolvedValue([]) },
diff --git a/src/lib/export/__tests__/full-backup-payload.test.ts b/src/lib/export/__tests__/full-backup-payload.test.ts
index 4a776c329..349a0fd8d 100644
--- a/src/lib/export/__tests__/full-backup-payload.test.ts
+++ b/src/lib/export/__tests__/full-backup-payload.test.ts
@@ -305,6 +305,10 @@ function makePrisma() {
     // same reason as the visit tables above.
     measurementReminder: { findMany: vi.fn().mockResolvedValue([]) },
     measurementReminderEvent: { findMany: vi.fn().mockResolvedValue([]) },
+    // The Coach transcript. Deliberately NOT `?? []` at the call site, so a
+    // future `include` that forgets the relation fails here loudly instead of
+    // exporting an account whose Coach never spoke.
+    coachConversation: { findMany: vi.fn().mockResolvedValue([]) },
     // Left unmocked on purpose: `buildProfileBackupSection` runs for real
     // against these, so the assertions below exercise the builder rather than
     // a stand-in that would agree with whatever the payload happened to do.
diff --git a/src/lib/export/backup-plan.ts b/src/lib/export/backup-plan.ts
index 16367a481..8893820c8 100644
--- a/src/lib/export/backup-plan.ts
+++ b/src/lib/export/backup-plan.ts
@@ -157,6 +157,11 @@ export const BACKED_UP_MODELS = [
   "VaccinationDocumentLink",
 
   // ── Coach ─────────────────────────────────────────────────────────────────
+  // The transcript — conversation, message, attachment — travels; see
+  // `src/lib/export/coach-backup.ts`. What is still owed is the Coach's
+  // MEMORY: the facts, plans and reminders it carries between threads. Each of
+  // those addresses a conversation by `sourceConversationId`, so they follow
+  // the transcript rather than lead it.
   "CoachConversation",
   "CoachMessage",
   "CoachConversationDocument",
@@ -211,6 +216,10 @@ export const BACKUP_WRITER_FILES: readonly string[] = [
   // The Vorsorge reminders and their completion ledger, both ends beside each
   // other like the visits and vaccinations above.
   "src/lib/export/reminders-backup.ts",
+  // The Coach transcript, same arrangement. `attachments` is a relation name
+  // this file shares with nothing else, but each model still reads through its
+  // own delegate here for the reason the visits comment gives.
+  "src/lib/export/coach-backup.ts",
   "src/lib/cycle/backup.ts",
 ];
 
@@ -222,6 +231,7 @@ export const BACKUP_RESTORE_FILES: readonly string[] = [
   "src/lib/export/visits-backup.ts",
   "src/lib/export/vaccinations-backup.ts",
   "src/lib/export/reminders-backup.ts",
+  "src/lib/export/coach-backup.ts",
   "src/lib/cycle/backup.ts",
 ];
 
@@ -306,6 +316,21 @@ export const TWO_ENDED_MODELS = [
   // dropping to NULL in the same release — the rows they name come back now.
   "MeasurementReminder",
   "MeasurementReminderEvent",
+  // The Coach's transcript. The register entry for the messages called them
+  // "the largest volume of free text an account owns after its documents",
+  // and until now a restored account got a Coach that had never spoken to it.
+  // The three travel together because two of them are meaningless alone: a
+  // turn without its thread has nowhere to hang, and an attachment names a
+  // pairing rather than a thing.
+  //
+  // `documentScoped` is the field that makes this more than history. It is a
+  // permanent fence — no code path lowers it — so a restore that let it
+  // default to false would hand the tool loop back to precisely the
+  // conversations the fence exists to keep away from it, invisibly. It is
+  // carried and asserted, not defaulted.
+  "CoachConversation",
+  "CoachMessage",
+  "CoachConversationDocument",
 ] as const;
 
 /** One model claimed to travel both ways. */
@@ -374,12 +399,6 @@ export const COVERAGE_PENDING: Readonly<Record<string, string>> = {
     "Which documents were filed against which condition. Documents and conditions both restore; the filing between them does not, so a restored vault is unsorted.",
   ExtractedFact:
     "Facts read out of a document by the AI pass, with their provenance back to the page. Re-derivable only by re-running the extraction against a provider, at the operator's cost.",
-  CoachConversation:
-    "The thread structure of past coaching conversations — which messages belong together and what each exchange was about. Without it the messages below, if they were ever carried, would restore as one undifferentiated pile.",
-  CoachMessage:
-    "The messages themselves, encrypted at rest. The largest volume of free text an account owns after its documents.",
-  CoachConversationDocument:
-    "Which documents a conversation was grounded in — the provenance that makes an old answer checkable.",
   CoachFact:
     "Durable facts the Coach was told to remember. A restore makes the account re-tell its history.",
   CoachPlan:
diff --git a/src/lib/export/coach-backup.ts b/src/lib/export/coach-backup.ts
new file mode 100644
index 000000000..c031d8340
--- /dev/null
+++ b/src/lib/export/coach-backup.ts
@@ -0,0 +1,440 @@
+/**
+ * The Coach's conversations, with both backup ends in one file.
+ *
+ * Same arrangement as `reminders-backup.ts`, `visits-backup.ts` and
+ * `vaccinations-backup.ts`, for the same reason: a reader asking "is this
+ * carried at both ends?" answers it here, and a reader who greps only the
+ * restore ROUTE gets a false negative because the route delegates.
+ *
+ * Three models ride: the conversation, its messages, and the join naming which
+ * vault documents a conversation was grounded in. All three sat on the
+ * coverage-pending register, where the entry for the messages read "the largest
+ * volume of free text an account owns after its documents". A restore without
+ * this section hands back an account whose Coach has never spoken to it.
+ *
+ * ## Three things this file is careful about
+ *
+ * **The fence flag is the important field.** `documentScoped` is a PERMANENT
+ * marker: it goes true when a conversation is created through the fenced
+ * endpoint or gets its first document, and no code path anywhere sets it back
+ * to false — not detaching every document, not deleting the document. A
+ * conversation whose history may contain document-derived text must never
+ * regain the tool loop. So it is carried verbatim and restored verbatim. A
+ * restore that let it default to false would hand the tool loop back to exactly
+ * the conversations the fence exists to keep away from it, and nothing in the
+ * interface would look wrong afterwards. It is the one field here where losing
+ * the value is a security regression rather than lost history.
+ *
+ * **Ids are carried in both modes**, as the reminders are, and for the same
+ * kind of reason: a message addresses its conversation, an attachment addresses
+ * both a conversation and a document, and the Coach's facts, plans and
+ * reminders carry a `sourceConversationId` that has to land somewhere real.
+ *
+ * **The prose follows the contract every other encrypted column here uses.** A
+ * disaster-recovery payload carries the stored ciphertext verbatim as base64,
+ * because the same instance's key reads it back unchanged. A portable export
+ * decrypts it, because a portable export exists to be readable by the person
+ * who owns it, exactly as it already decrypts medication notes, mood notes and
+ * document summaries. There is no third mode where a person's own words are
+ * withheld from their own export.
+ *
+ * ## The one reference that needs care
+ *
+ * `CoachConversationDocument.documentId` addresses a vault document, which is
+ * restored by the route BEFORE this section runs. A DR payload carries every
+ * document, so the reference always resolves. A portable payload never reaches
+ * a restore at all while the account has documents — the route refuses it
+ * ahead of the wipe, because document ciphertext is not in the file — so an
+ * attachment cannot survive into a restore whose document is missing. That
+ * leaves the hand-edited or truncated file, and there the row is dropped and
+ * REPORTED rather than invented, the same answer the ledger gives for a
+ * reminder it cannot find.
+ */
+import type { Prisma, PrismaClient } from "@/generated/prisma/client";
+
+import { decryptFromBytes, encryptToBytes } from "@/lib/ai/coach/bytes-codec";
+import {
+  recordUnknownKeys,
+  type RestoreSkipLog,
+} from "@/lib/export/restore-skips";
+
+export interface CoachBackupOptions {
+  purpose?: "portable-export" | "disaster-recovery";
+}
+
+/**
+ * One turn. `role` is the app-side pair "user" | "assistant", stored as a
+ * plain string rather than an enum, so it travels as written.
+ */
+export interface CoachMessageBackupEntry {
+  id: string;
+  role: string;
+  /** Ciphertext as base64. Present on a disaster-recovery payload only. */
+  contentEncrypted?: string;
+  /** Plaintext. Present on a portable payload only. */
+  content?: string;
+  metricSourceJson: string | null;
+  providerType: string | null;
+  promptVersion: string | null;
+  tokensUsed: number | null;
+  model: string | null;
+  createdAt: string;
+}
+
+/** Which vault document a conversation was grounded in. */
+export interface CoachConversationDocumentBackupEntry {
+  documentId: string;
+  addedAt: string;
+}
+
+export interface CoachConversationBackupEntry {
+  /** Always carried: messages, attachments and the Coach's own facts, plans
+   *  and reminders all address a conversation by it. */
+  id: string;
+  title: string;
+  /**
+   * The permanent fence marker. Carried and restored verbatim; see the file
+   * header for why letting this default is a security regression and not a
+   * cosmetic one.
+   */
+  documentScoped: boolean;
+  /** Rolling summary of elided older turns. Same codec as a message. */
+  summaryEncrypted?: string | null;
+  summary?: string | null;
+  summaryUpdatedAt: string | null;
+  summaryTurnCount: number;
+  createdAt: string;
+  updatedAt: string;
+  messages: CoachMessageBackupEntry[];
+  attachments: CoachConversationDocumentBackupEntry[];
+}
+
+export interface CoachBackupSection {
+  coachConversations: CoachConversationBackupEntry[];
+}
+
+export interface CoachBackupCounts {
+  coachConversations: number;
+  coachMessages: number;
+  coachConversationDocuments: number;
+}
+
+/**
+ * Every restorable `CoachConversation` scalar plus its two child relations.
+ *
+ * Named rather than inlined so a structural test can read the field list, and
+ * so a column added to the model shows up as a diff here rather than as a
+ * silent omission from the file.
+ */
+const COACH_CONVERSATION_BACKUP_SELECT = {
+  id: true,
+  title: true,
+  documentScoped: true,
+  summaryEncrypted: true,
+  summaryUpdatedAt: true,
+  summaryTurnCount: true,
+  createdAt: true,
+  updatedAt: true,
+  messages: {
+    orderBy: { createdAt: "asc" },
+    select: {
+      id: true,
+      role: true,
+      encryptedContent: true,
+      metricSourceJson: true,
+      providerType: true,
+      promptVersion: true,
+      tokensUsed: true,
+      model: true,
+      createdAt: true,
+    },
+  },
+  attachments: {
+    orderBy: { addedAt: "asc" },
+    select: { documentId: true, addedAt: true },
+  },
+} satisfies Prisma.CoachConversationSelect;
+
+/**
+ * Decrypt for a reader, or say plainly that this one turn could not be read.
+ *
+ * A single row encrypted under a key the instance has since dropped must not
+ * take the export down with it: the rest of the transcript is still the
+ * person's, and a thrown error would cost them all of it. The placeholder is
+ * deliberately a sentence rather than an empty string, because an empty string
+ * reads as "they said nothing here" and that is not what happened.
+ */
+function decryptTurnSoft(bytes: Uint8Array | null): string | null {
+  if (!bytes) return null;
+  try {
+    return decryptFromBytes(bytes);
+  } catch {
+    return "[unreadable: encrypted with a key this instance no longer holds]";
+  }
+}
+
+export async function buildCoachBackupSection(
+  prisma: Pick<PrismaClient, "coachConversation">,
+  userId: string,
+  options: CoachBackupOptions = {},
+): Promise<CoachBackupSection> {
+  const disasterRecovery = options.purpose === "disaster-recovery";
+
+  const rows = await prisma.coachConversation.findMany({
+    where: { userId },
+    orderBy: { createdAt: "asc" },
+    select: COACH_CONVERSATION_BACKUP_SELECT,
+  });
+
+  return {
+    coachConversations: rows.map((row) => ({
+      id: row.id,
+      title: row.title,
+      documentScoped: row.documentScoped,
+      ...(disasterRecovery
+        ? {
+            summaryEncrypted: row.summaryEncrypted
+              ? Buffer.from(row.summaryEncrypted).toString("base64")
+              : null,
+          }
+        : { summary: decryptTurnSoft(row.summaryEncrypted) }),
+      summaryUpdatedAt: row.summaryUpdatedAt?.toISOString() ?? null,
+      summaryTurnCount: row.summaryTurnCount,
+      createdAt: row.createdAt.toISOString(),
+      updatedAt: row.updatedAt.toISOString(),
+      messages: row.messages.map((message) => ({
+        id: message.id,
+        role: message.role,
+        ...(disasterRecovery
+          ? {
+              contentEncrypted: Buffer.from(message.encryptedContent).toString(
+                "base64",
+              ),
+            }
+          : { content: decryptTurnSoft(message.encryptedContent) ?? "" }),
+        metricSourceJson: message.metricSourceJson,
+        providerType: message.providerType,
+        promptVersion: message.promptVersion,
+        tokensUsed: message.tokensUsed,
+        model: message.model,
+        createdAt: message.createdAt.toISOString(),
+      })),
+      attachments: row.attachments.map((attachment) => ({
+        documentId: attachment.documentId,
+        addedAt: attachment.addedAt.toISOString(),
+      })),
+    })),
+  };
+}
+
+/** Row counts for the audit trail, mirroring the other section counters. */
+export function countCoachBackupSection(
+  section: CoachBackupSection,
+): CoachBackupCounts {
+  return {
+    coachConversations: section.coachConversations.length,
+    coachMessages: section.coachConversations.reduce(
+      (total, conversation) => total + conversation.messages.length,
+      0,
+    ),
+    coachConversationDocuments: section.coachConversations.reduce(
+      (total, conversation) => total + conversation.attachments.length,
+      0,
+    ),
+  };
+}
+
+/** Counts the Coach restore wiped, for the audit trail. */
+export interface CoachRestoreCleared {
+  coachConversations: number;
+  coachMessages: number;
+  coachConversationDocuments: number;
+}
+
+/**
+ * The slice of a parsed backup this restore consumes.
+ *
+ * Required rather than optional: the payload schema defaults the key, so every
+ * caller already satisfies this, and one that stops satisfying it fails to
+ * compile instead of quietly restoring nothing.
+ */
+export interface CoachRestoreInput {
+  coachConversations: RestoredCoachConversation[];
+}
+
+/**
+ * What the parser hands over, which is looser than what the builder writes.
+ *
+ * The wire schema defaults or leaves optional every field an older file might
+ * not carry, so the restore reads that shape rather than the builder's. The
+ * one field kept strictly required is `documentScoped`: a file that does not
+ * state the fence must not be silently re-fenced to the permissive value, and
+ * making it optional here would let exactly that compile.
+ */
+type OptionalNullable<T> = { [K in keyof T]?: T[K] | undefined };
+
+export type RestoredCoachMessage = Pick<
+  CoachMessageBackupEntry,
+  "id" | "role" | "createdAt"
+> &
+  OptionalNullable<
+    Pick<
+      CoachMessageBackupEntry,
+      | "contentEncrypted"
+      | "content"
+      | "metricSourceJson"
+      | "providerType"
+      | "promptVersion"
+      | "tokensUsed"
+      | "model"
+    >
+  >;
+
+export type RestoredCoachConversation = Pick<
+  CoachConversationBackupEntry,
+  "id" | "title" | "documentScoped" | "createdAt" | "updatedAt"
+> &
+  OptionalNullable<
+    Pick<
+      CoachConversationBackupEntry,
+      "summaryEncrypted" | "summary" | "summaryUpdatedAt" | "summaryTurnCount"
+    >
+  > & {
+    messages: RestoredCoachMessage[];
+    attachments: CoachConversationDocumentBackupEntry[];
+  };
+
+/**
+ * Re-create the account's Coach conversations, turns and document links.
+ *
+ * Delete-then-recreate inside the caller's transaction, matching every other
+ * section. Messages and attachments cascade from the conversation, so deleting
+ * the conversations is enough to empty them — they are counted first anyway, so
+ * the cleared numbers are truthful rather than "whatever the cascade took".
+ *
+ * MUST be called AFTER the vault documents are restored: an attachment carries
+ * a `documentId` that is a foreign key against them, and running earlier would
+ * make every attachment unresolvable.
+ *
+ * `documentIds` is the set of documents the restore actually put back, passed
+ * in rather than re-queried so this stays a pure function of the transaction it
+ * was handed. An attachment naming anything outside it is dropped and reported.
+ */
+export async function restoreCoachData(
+  tx: Prisma.TransactionClient,
+  ownerId: string,
+  payload: CoachRestoreInput,
+  documentIds: ReadonlySet<string>,
+  skips: RestoreSkipLog,
+): Promise<CoachRestoreCleared> {
+  const [clearedMessages, clearedAttachments] = await Promise.all([
+    tx.coachMessage.count({ where: { conversation: { userId: ownerId } } }),
+    tx.coachConversationDocument.count({
+      where: { conversation: { userId: ownerId } },
+    }),
+  ]);
+  const clearedConversations = await tx.coachConversation.deleteMany({
+    where: { userId: ownerId },
+  });
+
+  for (const conversation of payload.coachConversations) {
+    await tx.coachConversation.create({
+      data: {
+        id: conversation.id,
+        userId: ownerId,
+        title: conversation.title,
+        // Verbatim. See the file header: this is the one field whose loss is a
+        // security regression rather than a gap in the history.
+        documentScoped: conversation.documentScoped,
+        summaryEncrypted: resolveSummaryBytes(conversation),
+        summaryUpdatedAt: conversation.summaryUpdatedAt
+          ? new Date(conversation.summaryUpdatedAt)
+          : null,
+        summaryTurnCount: conversation.summaryTurnCount ?? 0,
+        createdAt: new Date(conversation.createdAt),
+        updatedAt: new Date(conversation.updatedAt),
+        messages: {
+          create: conversation.messages.map((message) => ({
+            id: message.id,
+            role: message.role,
+            encryptedContent: resolveTurnBytes(message),
+            metricSourceJson: message.metricSourceJson ?? null,
+            providerType: message.providerType ?? null,
+            promptVersion: message.promptVersion ?? null,
+            tokensUsed: message.tokensUsed ?? null,
+            model: message.model ?? null,
+            createdAt: new Date(message.createdAt),
+          })),
+        },
+      },
+    });
+  }
+
+  // The attachments go in a second pass so a dropped document reference costs
+  // one link rather than the conversation that held it.
+  const droppedDocumentRefs: string[] = [];
+  for (const conversation of payload.coachConversations) {
+    const writable = conversation.attachments.filter((attachment) => {
+      if (documentIds.has(attachment.documentId)) return true;
+      droppedDocumentRefs.push(attachment.documentId);
+      return false;
+    });
+    if (writable.length === 0) continue;
+    await tx.coachConversationDocument.createMany({
+      data: writable.map((attachment) => ({
+        conversationId: conversation.id,
+        documentId: attachment.documentId,
+        addedAt: new Date(attachment.addedAt),
+      })),
+    });
+  }
+  recordUnknownKeys(
+    skips,
+    "coachAttachment",
+    [...new Set(droppedDocumentRefs)],
+    droppedDocumentRefs,
+  );
+
+  return {
+    coachConversations: clearedConversations.count,
+    coachMessages: clearedMessages,
+    coachConversationDocuments: clearedAttachments,
+  };
+}
+
+/**
+ * A turn's stored bytes, whichever end of the contract the file came from.
+ *
+ * A disaster-recovery file carries ciphertext that decodes straight back into
+ * the column. A portable file carries plaintext, which has to be encrypted on
+ * the way in — the target instance's key, not the source's, which is the whole
+ * point of a portable file being portable.
+ */
+function resolveTurnBytes(
+  message: RestoredCoachMessage,
+): Uint8Array<ArrayBuffer> {
+  if (message.contentEncrypted !== undefined) {
+    return decodeBase64(message.contentEncrypted);
+  }
+  return encryptToBytes(message.content ?? "");
+}
+
+function resolveSummaryBytes(
+  conversation: RestoredCoachConversation,
+): Uint8Array<ArrayBuffer> | null {
+  if (conversation.summaryEncrypted !== undefined) {
+    return conversation.summaryEncrypted === null
+      ? null
+      : decodeBase64(conversation.summaryEncrypted);
+  }
+  // A portable file with no summary and one with an empty summary are the same
+  // thing to a reader, and neither should write a zero-byte ciphertext.
+  return conversation.summary ? encryptToBytes(conversation.summary) : null;
+}
+
+function decodeBase64(encoded: string): Uint8Array<ArrayBuffer> {
+  const decoded = Buffer.from(encoded, "base64");
+  const bytes = new Uint8Array(new ArrayBuffer(decoded.byteLength));
+  bytes.set(decoded);
+  return bytes;
+}
diff --git a/src/lib/export/full-backup-payload.ts b/src/lib/export/full-backup-payload.ts
index c34e73696..6c79f9f92 100644
--- a/src/lib/export/full-backup-payload.ts
+++ b/src/lib/export/full-backup-payload.ts
@@ -55,6 +55,12 @@ import {
   type RemindersBackupCounts,
   type RemindersBackupSection,
 } from "@/lib/export/reminders-backup";
+import {
+  buildCoachBackupSection,
+  countCoachBackupSection,
+  type CoachBackupCounts,
+  type CoachBackupSection,
+} from "@/lib/export/coach-backup";
 import {
   buildIntradayProfileBackupSection,
   countIntradayProfileBackupSection,
@@ -70,7 +76,8 @@ export interface FullBackupCounts
     HealthScoreBackupCounts,
     VisitsBackupCounts,
     VaccinationsBackupCounts,
-    RemindersBackupCounts {
+    RemindersBackupCounts,
+    CoachBackupCounts {
   measurements: number;
   medications: number;
   intakeEvents: number;
@@ -287,6 +294,7 @@ export async function buildFullBackupPayload(
     visits,
     vaccinations,
     reminders,
+    coach,
     nutrientDays,
   ] = await Promise.all([
     disasterRecovery
@@ -435,6 +443,12 @@ export async function buildFullBackupPayload(
     buildRemindersBackupSection(prisma, userId, {
       purpose: disasterRecovery ? "disaster-recovery" : "portable-export",
     }),
+    // The Coach's conversations, turns and document links. Both ends live in
+    // `src/lib/export/coach-backup.ts` beside each other, the same arrangement
+    // as the three sections above and for the same reason.
+    buildCoachBackupSection(prisma, userId, {
+      purpose: disasterRecovery ? "disaster-recovery" : "portable-export",
+    }),
     // Nutrient day totals were absent from every export path, which
     // contradicted the schema's own reason for denormalising the unit column
     // ("rows stay self-describing in exports even if the catalog ever drifts").
@@ -464,6 +478,7 @@ export async function buildFullBackupPayload(
   const visitsSection: VisitsBackupSection = visits;
   const vaccinationsSection: VaccinationsBackupSection = vaccinations;
   const remindersSection: RemindersBackupSection = reminders;
+  const coachSection: CoachBackupSection = coach;
 
   const payload = {
     schemaVersion: BACKUP_SCHEMA_VERSION,
@@ -742,6 +757,7 @@ export async function buildFullBackupPayload(
     ...visitsSection,
     ...vaccinationsSection,
     ...remindersSection,
+    ...coachSection,
     nutrientDays: nutrientDays.map((n) => ({
       day: n.day,
       nutrient: n.nutrient,
@@ -780,6 +796,7 @@ export async function buildFullBackupPayload(
       ...countVisitsBackupSection(visits),
       ...countVaccinationsBackupSection(vaccinations),
       ...countRemindersBackupSection(reminders),
+      ...countCoachBackupSection(coach),
     },
   };
 }
diff --git a/src/lib/export/restore-skips.ts b/src/lib/export/restore-skips.ts
index 4336bf999..8c93f19cb 100644
--- a/src/lib/export/restore-skips.ts
+++ b/src/lib/export/restore-skips.ts
@@ -55,7 +55,16 @@
  * it exists for the hand-edited or truncated file, where inventing the
  * reminder and silently dropping the row are equally wrong.
  *
- * The eighth, `checkupClosure`, is not about a restore at all, and it borrows
+ * The eighth, `coachAttachment`, is the same kind again, for the join naming
+ * which vault documents a Coach conversation was grounded in. The document is
+ * restored before the conversations are, so a file this release writes always
+ * resolves: a disaster-recovery payload carries every document, and a portable
+ * payload never reaches a restore while the account has any, because the route
+ * refuses it ahead of the wipe. It exists for the hand-edited or truncated
+ * file, where inventing the document and silently dropping the provenance are
+ * equally wrong.
+ *
+ * The ninth, `checkupClosure`, is not about a restore at all, and it borrows
  * this shape deliberately rather than growing a second reporting mechanism
  * beside it. The situation is the same one: something a write was asked to do
  * could not be done, the record itself survives, and the person is told which
@@ -71,6 +80,7 @@ export type SkippedCatalogue =
   | "visitReference"
   | "vaccinationReference"
   | "reminderReference"
+  | "coachAttachment"
   | "checkupClosure";
 
 /** One key this instance does not know, and the links it cost. */
diff --git a/src/lib/validations/backup.ts b/src/lib/validations/backup.ts
index 092741828..b8cc8026d 100644
--- a/src/lib/validations/backup.ts
+++ b/src/lib/validations/backup.ts
@@ -1042,6 +1042,57 @@ const measurementReminderEventBackupSchema = z
   })
   .passthrough();
 
+/**
+ * One Coach turn.
+ *
+ * `contentEncrypted` and `content` are the two ends of the same contract, so
+ * both are optional here and exactly one arrives: a disaster-recovery file
+ * carries the ciphertext, a portable file carries the prose. Requiring either
+ * would refuse half the valid files; requiring both would refuse all of them.
+ * The restore picks whichever it was handed.
+ */
+const coachMessageBackupSchema = z
+  .object({
+    id: z.string().min(1),
+    role: z.string().min(1),
+    contentEncrypted: base64BytesSchema.optional(),
+    content: z.string().optional(),
+    metricSourceJson: z.string().nullable().optional(),
+    providerType: z.string().nullable().optional(),
+    promptVersion: z.string().nullable().optional(),
+    tokensUsed: z.number().int().nullable().optional(),
+    model: z.string().nullable().optional(),
+    createdAt: isoDateTime,
+  })
+  .passthrough();
+
+const coachConversationDocumentBackupSchema = z
+  .object({
+    documentId: z.string().min(1),
+    addedAt: isoDateTime,
+  })
+  .passthrough();
+
+const coachConversationBackupSchema = z
+  .object({
+    id: z.string().min(1),
+    title: z.string(),
+    // NOT optional with a default. The fence is permanent and a file that does
+    // not state it is a file that cannot be trusted to re-fence the
+    // conversation, so the absence has to be visible rather than defaulted to
+    // the permissive value.
+    documentScoped: z.boolean(),
+    summaryEncrypted: base64BytesSchema.nullable().optional(),
+    summary: z.string().nullable().optional(),
+    summaryUpdatedAt: isoDateTime.nullable().optional(),
+    summaryTurnCount: z.number().int().min(0).optional(),
+    createdAt: isoDateTime,
+    updatedAt: isoDateTime,
+    messages: z.array(coachMessageBackupSchema).default([]),
+    attachments: z.array(coachConversationDocumentBackupSchema).default([]),
+  })
+  .passthrough();
+
 const allergyBackupSchema = z
   .object({
     id: z.string().min(1),
@@ -1208,6 +1259,7 @@ export const backupPayloadSchema = z
     // iOS #68). Defaulted for the same reason as the sections above: a file
     // written before the reminders travelled carries no key, and an account
     // with none writes [].
+    coachConversations: z.array(coachConversationBackupSchema).default([]),
     measurementReminders: z.array(measurementReminderBackupSchema).default([]),
     measurementReminderEvents: z
       .array(measurementReminderEventBackupSchema)
@@ -1298,6 +1350,10 @@ export interface BackupSummary {
   measurementReminders: number;
   /** v1.37.20 (#223 / iOS #68) — completion-ledger rows across every reminder. */
   measurementReminderEvents: number;
+  /** Coach conversation threads. */
+  coachConversations: number;
+  /** Coach turns across every thread. */
+  coachMessages: number;
 }
 
 export function summarizeBackup(payload: BackupPayload): BackupSummary {
@@ -1354,6 +1410,11 @@ export function summarizeBackup(payload: BackupPayload): BackupSummary {
     // file with reminders the way it once did for visits.
     measurementReminders: payload.measurementReminders.length,
     measurementReminderEvents: payload.measurementReminderEvents.length,
+    coachConversations: payload.coachConversations.length,
+    coachMessages: payload.coachConversations.reduce(
+      (total, conversation) => total + conversation.messages.length,
+      0,
+    ),
   };
 }
 
diff --git a/tests/integration/backup-round-trip.test.ts b/tests/integration/backup-round-trip.test.ts
index f1670215e..8585e5ff1 100644
--- a/tests/integration/backup-round-trip.test.ts
+++ b/tests/integration/backup-round-trip.test.ts
@@ -82,6 +82,10 @@ vi.mock("@/lib/cache/invalidate", () => ({
 
 const OWNER_ID = "round-trip-owner";
 const AT = (iso: string) => new Date(iso);
+const COACH_SUMMARY = "earlier turns: weight trend and evening walks";
+const COACH_USER_TURN = "my readings look higher this week, is that real?";
+const COACH_ASSISTANT_TURN =
+  "the last seven mornings average 4 mmHg above the fortnight before";
 const DOSE_CHANGE_NOTE = "titration note, encrypted at rest";
 const SIDE_EFFECT_NOTE = "nausea for two hours after the evening dose";
 
@@ -163,6 +167,14 @@ const COUNT_BACK: Record<
     p.measurementReminder.count({ where: { userId } }),
   MeasurementReminderEvent: (p, userId) =>
     p.measurementReminderEvent.count({ where: { userId } }),
+  CoachConversation: (p, userId) =>
+    p.coachConversation.count({ where: { userId } }),
+  // Neither the turn nor the attachment carries its own `userId` — both are
+  // reached through the thread that holds them.
+  CoachMessage: (p, userId) =>
+    p.coachMessage.count({ where: { conversation: { userId } } }),
+  CoachConversationDocument: (p, userId) =>
+    p.coachConversationDocument.count({ where: { conversation: { userId } } }),
 };
 
 /**
@@ -475,6 +487,62 @@ async function seedEveryTwoEndedModel(prisma: PrismaClient): Promise<void> {
     },
   });
 
+  // Two Coach threads, and the pair is the point. One is an ordinary health
+  // conversation; the other is FENCED — `documentScoped` true, grounded in the
+  // document seeded above. A restore that let the flag default to false would
+  // return both threads, satisfy every count, and quietly hand the tool loop
+  // back to the one conversation whose history may contain document-derived
+  // text. That is why the assertion below reads the flag per thread rather
+  // than counting rows.
+  await prisma.coachConversation.create({
+    data: {
+      userId: OWNER_ID,
+      title: "How is my blood pressure trending?",
+      documentScoped: false,
+      summaryEncrypted: encryptToBytes(COACH_SUMMARY),
+      summaryUpdatedAt: AT("2026-07-20T10:00:00.000Z"),
+      summaryTurnCount: 4,
+      messages: {
+        create: [
+          {
+            role: "user",
+            encryptedContent: encryptToBytes(COACH_USER_TURN),
+            createdAt: AT("2026-07-20T09:58:00.000Z"),
+          },
+          {
+            role: "assistant",
+            encryptedContent: encryptToBytes(COACH_ASSISTANT_TURN),
+            providerType: "anthropic",
+            model: "claude-opus-5",
+            tokensUsed: 812,
+            createdAt: AT("2026-07-20T09:59:00.000Z"),
+          },
+        ],
+      },
+    },
+  });
+  await prisma.coachConversation.create({
+    data: {
+      userId: OWNER_ID,
+      title: "About my June labs",
+      documentScoped: true,
+      messages: {
+        create: [
+          {
+            role: "user",
+            encryptedContent: encryptToBytes("What does the ferritin mean?"),
+            createdAt: AT("2026-07-21T08:00:00.000Z"),
+          },
+        ],
+      },
+      attachments: {
+        create: [
+          { documentId: document.id, addedAt: AT("2026-07-21T07:59:00.000Z") },
+        ],
+      },
+    },
+  });
+
   // One visit, the practice it was at, and one link of each of the three
   // kinds. The links reach the document, the lab result and the condition
   // episode seeded above rather than fresh rows, because a link to something
@@ -757,6 +825,82 @@ describe("every model the plan claims two-ended survives a real restore", () =>
       { pausedAt: "2026-07-15T08:00:00.000Z", resumedAt: null },
     ]);
 
+    // The Coach came back able to speak, and the fence held.
+    //
+    // `documentScoped` is asserted per thread rather than in aggregate: a
+    // restore that wrote `false` everywhere would still return two threads,
+    // two counts and every turn, and the only visible difference would be a
+    // fenced conversation quietly holding a tool loop again.
+    // Resolved from the database rather than remembered from the fixture: the
+    // attachment has to point at the document the RESTORE put back, not at an
+    // id that happens to match one the seeding used.
+    const vaultDocument = await prisma.inboundDocument.findFirstOrThrow({
+      where: { userId: OWNER_ID },
+    });
+    const threads = await prisma.coachConversation.findMany({
+      where: { userId: OWNER_ID },
+      orderBy: { createdAt: "asc" },
+      include: {
+        messages: { orderBy: { createdAt: "asc" } },
+        attachments: true,
+      },
+    });
+    expect(
+      threads.map((thread) => ({
+        title: thread.title,
+        documentScoped: thread.documentScoped,
+        summary: thread.summaryEncrypted
+          ? decryptFromBytes(thread.summaryEncrypted)
+          : null,
+        summaryTurnCount: thread.summaryTurnCount,
+        turns: thread.messages.map((message) => ({
+          role: message.role,
+          content: decryptFromBytes(message.encryptedContent),
+          model: message.model,
+          tokensUsed: message.tokensUsed,
+        })),
+        attachments: thread.attachments.map((a) => a.documentId),
+      })),
+      "the transcript, the fence and the provenance all come back",
+    ).toEqual([
+      {
+        title: "How is my blood pressure trending?",
+        documentScoped: false,
+        summary: COACH_SUMMARY,
+        summaryTurnCount: 4,
+        turns: [
+          {
+            role: "user",
+            content: COACH_USER_TURN,
+            model: null,
+            tokensUsed: null,
+          },
+          {
+            role: "assistant",
+            content: COACH_ASSISTANT_TURN,
+            model: "claude-opus-5",
+            tokensUsed: 812,
+          },
+        ],
+        attachments: [],
+      },
+      {
+        title: "About my June labs",
+        documentScoped: true,
+        summary: null,
+        summaryTurnCount: 0,
+        turns: [
+          {
+            role: "user",
+            content: "What does the ferritin mean?",
+            model: null,
+            tokensUsed: null,
+          },
+        ],
+        attachments: [vaultDocument.id],
+      },
+    ]);
+
     // The ramp, in order, with the note back in its column. Counting says two
     // rows returned; only this says they came back as the same ramp, and that
     // the encrypted note did not land in the plaintext column on the way.