diff --git a/src/__tests__/backup-schema-lazy-guard.test.ts b/src/__tests__/backup-schema-lazy-guard.test.ts
new file mode 100644
index 000000000..7edfd07fb
--- /dev/null
+++ b/src/__tests__/backup-schema-lazy-guard.test.ts
@@ -0,0 +1,75 @@
+/**
+ * `backupPayloadSchema` is built when `src/lib/validations/backup.ts` is
+ * evaluated and holds about 12 MB of heap. The restore job, the stored-backup
+ * readers and the export writer sit on the boot path, so a static value import
+ * of that module from any of them puts the schema in every server process,
+ * whether or not it ever touches a backup. Runtime code reaches it with a
+ * dynamic `import()` at the moment a file is validated, takes only types
+ * statically, and takes the version and the summary from `backup-summary.ts`.
+ *
+ * The one static importer allowed is the OpenAPI registry, which only the
+ * spec generator loads.
+ */
+import { readdirSync, readFileSync, statSync } from "node:fs";
+import { join, relative } from "node:path";
+import { describe, expect, it } from "vitest";
+
+const ROOT = join(__dirname, "..");
+const ALLOWED_STATIC = new Set(["lib/openapi/routes/export.ts"]);
+
+function sourceFiles(dir: string): string[] {
+  const out: string[] = [];
+  for (const name of readdirSync(dir)) {
+    const path = join(dir, name);
+    if (name === "__tests__" || name === "generated") continue;
+    if (statSync(path).isDirectory()) out.push(...sourceFiles(path));
+    else if (/\.(ts|tsx)$/.test(name) && !/\.test\.tsx?$/.test(name)) {
+      out.push(path);
+    }
+  }
+  return out;
+}
+
+// `import … from "@/lib/validations/backup"`, across lines, capturing what
+// precedes the specifier. Every importer uses the alias (a relative
+// `./backup` also names `src/lib/cycle/backup.ts`, so it is not matched).
+const STATIC_IMPORT =
+  /^import\s+(type\s+)?([^;]*?)\s+from\s+["']@\/lib\/validations\/backup["']/gm;
+const DYNAMIC_IMPORT = /import\(\s*["']@\/lib\/validations\/backup["']\s*\)/g;
+
+describe("the backup payload schema loads on first use", () => {
+  const files = sourceFiles(ROOT);
+  const staticValueImporters: string[] = [];
+  let dynamicImports = 0;
+  let typeImports = 0;
+
+  for (const file of files) {
+    const rel = relative(ROOT, file);
+    if (rel === "lib/validations/backup.ts") continue;
+    const text = readFileSync(file, "utf8");
+    for (const match of text.matchAll(STATIC_IMPORT)) {
+      const typeOnly =
+        match[1] !== undefined ||
+        (/^\{[^}]*\}$/.test(match[2]) &&
+          match[2]
+            .slice(1, -1)
+            .split(",")
+            .map((s) => s.trim())
+            .filter(Boolean)
+            .every((s) => s.startsWith("type ")));
+      if (typeOnly) typeImports++;
+      else if (!ALLOWED_STATIC.has(rel)) staticValueImporters.push(rel);
+    }
+    dynamicImports += [...text.matchAll(DYNAMIC_IMPORT)].length;
+  }
+
+  it("has no static value import outside the OpenAPI registry", () => {
+    expect(staticValueImporters).toEqual([]);
+  });
+
+  it("finds the loaders it guards (an empty match set would pass vacuously)", () => {
+    // upload, restore, preview (store + summary route), download, streamed reader
+    expect(dynamicImports).toBeGreaterThanOrEqual(5);
+    expect(typeImports).toBeGreaterThan(0);
+  });
+});
diff --git a/src/app/api/admin/backups/[id]/download/route.ts b/src/app/api/admin/backups/[id]/download/route.ts
index d79aca81d..bf5e3c096 100644
--- a/src/app/api/admin/backups/[id]/download/route.ts
+++ b/src/app/api/admin/backups/[id]/download/route.ts
@@ -38,7 +38,6 @@ import {
   type StreamedBackup,
 } from "@/lib/export/streamed-backup";
 import { annotate } from "@/lib/logging/context";
-import { parseBackupPayload } from "@/lib/validations/backup";
 
 export const dynamic = "force-dynamic";
 
@@ -108,6 +107,8 @@ export const GET = apiHandler(
     let streamed: StreamedBackup;
     try {
       streamed = await readStreamedBackup(source);
+      // Loaded on first use, not at import (see `backup-summary.ts`).
+      const { parseBackupPayload } = await import("@/lib/validations/backup");
       parseBackupPayload(streamed.raw);
     } catch (err) {
       const readFailure = isStoredBackupReadError(err);
diff --git a/src/app/api/admin/backups/[id]/summary/__tests__/route.test.ts b/src/app/api/admin/backups/[id]/summary/__tests__/route.test.ts
index 9c95d3f8b..417ab2277 100644
--- a/src/app/api/admin/backups/[id]/summary/__tests__/route.test.ts
+++ b/src/app/api/admin/backups/[id]/summary/__tests__/route.test.ts
@@ -67,14 +67,16 @@ const summarizeMock = vi.fn();
 const compatibleMock = vi.fn((version: string) => version !== "99");
 vi.mock("@/lib/validations/backup", () => ({
   parseBackupPayload: (...a: unknown[]) => parseMock(...a),
-  summarizeBackup: (...a: unknown[]) => summarizeMock(...a),
-  isCompatibleSchemaVersion: (version: string) => compatibleMock(version),
   // The measurements are read as a stream and counted one by one.
-  BACKUP_SCHEMA_VERSION: "2",
   backupMeasurementSchema: {
     safeParse: (value: unknown) => ({ success: true, data: value }),
   },
 }));
+vi.mock("@/lib/validations/backup-summary", () => ({
+  summarizeBackup: (...a: unknown[]) => summarizeMock(...a),
+  isCompatibleSchemaVersion: (version: string) => compatibleMock(version),
+  BACKUP_SCHEMA_VERSION: "2",
+}));
 
 import { GET } from "../route";
 import { storedCopyIdentity } from "@/lib/export/backup-preview";
diff --git a/src/app/api/admin/backups/[id]/summary/route.ts b/src/app/api/admin/backups/[id]/summary/route.ts
index 36862e792..bc8eacfc3 100644
--- a/src/app/api/admin/backups/[id]/summary/route.ts
+++ b/src/app/api/admin/backups/[id]/summary/route.ts
@@ -59,9 +59,8 @@ import {
 import { annotate } from "@/lib/logging/context";
 import {
   isCompatibleSchemaVersion,
-  parseBackupPayload,
   summarizeBackup,
-} from "@/lib/validations/backup";
+} from "@/lib/validations/backup-summary";
 
 export const dynamic = "force-dynamic";
 
@@ -123,6 +122,8 @@ async function readPreview(
 
   try {
     const streamed = await readStreamedBackup(source);
+    // Loaded on first use, not at import (see `backup-summary.ts`).
+    const { parseBackupPayload } = await import("@/lib/validations/backup");
     const payload = parseBackupPayload(streamed.raw);
     const summary = {
       ...summarizeBackup(payload),
diff --git a/src/app/api/admin/backups/upload/route.ts b/src/app/api/admin/backups/upload/route.ts
index 063dbf978..b0d14a5ea 100644
--- a/src/app/api/admin/backups/upload/route.ts
+++ b/src/app/api/admin/backups/upload/route.ts
@@ -61,15 +61,13 @@ import { storeBackupBlob } from "@/lib/export/store-backup-blob";
 import { StreamedBackupInvalidError } from "@/lib/export/streamed-backup";
 import { annotate } from "@/lib/logging/context";
 import { checkRateLimit } from "@/lib/rate-limit";
+import type { BackupPayload } from "@/lib/validations/backup";
 import {
   BACKUP_SCHEMA_VERSION,
-  backupMeasurementSchema,
-  backupPayloadSchema,
   isCompatibleSchemaVersion,
   summarizeBackup,
-  type BackupPayload,
   type BackupSummary,
-} from "@/lib/validations/backup";
+} from "@/lib/validations/backup-summary";
 
 export const dynamic = "force-dynamic";
 
@@ -252,6 +250,9 @@ export const POST = apiHandler(async (request: NextRequest) => {
             yield chunk;
           }
         }
+        // Loaded on first use, not at import (see `backup-summary.ts`).
+        const { backupMeasurementSchema, backupPayloadSchema } =
+          await import("@/lib/validations/backup");
         let firstWithoutId: number | null = null;
         let scanned;
         try {
diff --git a/src/lib/export/__tests__/backup-preview.test.ts b/src/lib/export/__tests__/backup-preview.test.ts
index 688087675..8016c6c4c 100644
--- a/src/lib/export/__tests__/backup-preview.test.ts
+++ b/src/lib/export/__tests__/backup-preview.test.ts
@@ -20,7 +20,8 @@ import {
   storedPreviewFor,
 } from "@/lib/export/backup-preview";
 import type { FullBackupCounts } from "@/lib/export/full-backup-payload";
-import { backupPayloadSchema, summarizeBackup } from "@/lib/validations/backup";
+import { backupPayloadSchema } from "@/lib/validations/backup";
+import { summarizeBackup } from "@/lib/validations/backup-summary";
 
 const ts = "2026-07-19T07:00:00.000Z";
 /** A bytes-column value holding the string codec under key id `v3`. */
diff --git a/src/lib/export/__tests__/restore-backup-owner-mismatch.test.ts b/src/lib/export/__tests__/restore-backup-owner-mismatch.test.ts
index 457fcb7d9..f23c35dea 100644
--- a/src/lib/export/__tests__/restore-backup-owner-mismatch.test.ts
+++ b/src/lib/export/__tests__/restore-backup-owner-mismatch.test.ts
@@ -31,11 +31,13 @@ vi.mock("@/lib/crypto", () => ({
 vi.mock("@/lib/crypto/note-cipher", () => ({ encryptNote: vi.fn() }));
 vi.mock("@/lib/validations/backup", () => ({
   parseBackupPayload: vi.fn(),
+  // The streamed reader checks measurements one at a time; this file has none.
+  backupMeasurementSchema: { safeParse: vi.fn() },
+}));
+vi.mock("@/lib/validations/backup-summary", () => ({
   isCompatibleSchemaVersion: vi.fn(() => true),
   summarizeBackup: vi.fn(() => ({})),
-  // The streamed reader checks measurements one at a time; this file has none.
   BACKUP_SCHEMA_VERSION: "2",
-  backupMeasurementSchema: { safeParse: vi.fn() },
 }));
 vi.mock("@/lib/auth/audit", () => ({ auditLog: vi.fn() }));
 vi.mock("@/lib/logging/context", () => ({ annotate: vi.fn() }));
diff --git a/src/lib/export/backup-preview.ts b/src/lib/export/backup-preview.ts
index c96be0554..91eebab21 100644
--- a/src/lib/export/backup-preview.ts
+++ b/src/lib/export/backup-preview.ts
@@ -35,7 +35,7 @@ import {
 } from "@/lib/export/backup-key-ids";
 import type { FullBackupCounts } from "@/lib/export/full-backup-payload";
 import type { StoredBackupRef } from "@/lib/export/stored-backup";
-import type { BackupSummary } from "@/lib/validations/backup";
+import type { BackupSummary } from "@/lib/validations/backup-summary";
 
 export interface BackupPreview {
   version: 1;
diff --git a/src/lib/export/full-backup-payload.ts b/src/lib/export/full-backup-payload.ts
index f96f79935..802f492c0 100644
--- a/src/lib/export/full-backup-payload.ts
+++ b/src/lib/export/full-backup-payload.ts
@@ -27,7 +27,7 @@ import type { Prisma, PrismaClient } from "@/generated/prisma/client";
 import { readNote } from "@/lib/crypto/note-cipher";
 import { openSealedForExport } from "@/lib/export/sealed-text";
 import { iterateMeasurementPages } from "@/lib/export/paged-measurements";
-import { BACKUP_SCHEMA_VERSION } from "@/lib/validations/backup";
+import { BACKUP_SCHEMA_VERSION } from "@/lib/validations/backup-summary";
 import {
   buildCycleBackupSection,
   type CycleBackupSection,
diff --git a/src/lib/export/restore-backup.ts b/src/lib/export/restore-backup.ts
index e0bd34eef..21c702f21 100644
--- a/src/lib/export/restore-backup.ts
+++ b/src/lib/export/restore-backup.ts
@@ -71,13 +71,12 @@ import { encryptToBytes } from "@/lib/ai/coach/bytes-codec";
 import { encryptContextToBytes } from "@/lib/labs/biomarker-store";
 import { encryptNoteToBytes } from "@/lib/labs/store";
 import { annotate } from "@/lib/logging/context";
+import type { BackupMeasurement } from "@/lib/validations/backup";
 import {
-  parseBackupPayload,
   isCompatibleSchemaVersion,
   summarizeBackup,
-  type BackupMeasurement,
   type BackupSummary,
-} from "@/lib/validations/backup";
+} from "@/lib/validations/backup-summary";
 import { recomputeUserMoodRollups } from "@/lib/rollups/mood-rollups";
 import {
   recomputeUserMedicationCompliance,
@@ -431,6 +430,9 @@ export async function restoreBackup(
     progress.measurementsTotal = streamed.measurementCount;
     report("validating", true);
     raw = streamed.raw;
+    // Loaded here, not at import: the schema is ~12 MB of heap and a server
+    // that never validates a backup should not hold it (`backup-summary.ts`).
+    const { parseBackupPayload } = await import("@/lib/validations/backup");
     payload = parseBackupPayload(raw);
   } catch (err) {
     const readFailure = isStoredBackupReadError(err);
diff --git a/src/lib/export/store-backup-blob.ts b/src/lib/export/store-backup-blob.ts
index 2b9fe6a11..ec5a0543f 100644
--- a/src/lib/export/store-backup-blob.ts
+++ b/src/lib/export/store-backup-blob.ts
@@ -48,7 +48,7 @@ import {
   newChunkStreamId,
 } from "@/lib/export/backup-chunks";
 import { BackupFormsConflictError } from "@/lib/export/stored-backup";
-import type { BackupSummary } from "@/lib/validations/backup";
+import type { BackupSummary } from "@/lib/validations/backup-summary";
 
 /**
  * How long the storing transaction may stay open. The job around it expires
diff --git a/src/lib/export/streamed-backup.ts b/src/lib/export/streamed-backup.ts
index b87c1b848..15bece054 100644
--- a/src/lib/export/streamed-backup.ts
+++ b/src/lib/export/streamed-backup.ts
@@ -23,11 +23,22 @@
  */
 import { BackupKeyIdCollector } from "@/lib/export/backup-key-ids";
 import { scanBackupJson } from "@/lib/export/backup-json-scan";
-import {
-  BACKUP_SCHEMA_VERSION,
+import type {
+  BackupMeasurement,
   backupMeasurementSchema,
-  type BackupMeasurement,
 } from "@/lib/validations/backup";
+import { BACKUP_SCHEMA_VERSION } from "@/lib/validations/backup-summary";
+
+type MeasurementSchema = typeof backupMeasurementSchema;
+
+/**
+ * The element schema, loaded with the rest of `backup.ts` on the first read
+ * rather than at import: the module sits on the boot path of the restore job
+ * and the schema is ~12 MB of heap (`backup-summary.ts`).
+ */
+async function loadMeasurementSchema(): Promise<MeasurementSchema> {
+  return (await import("@/lib/validations/backup")).backupMeasurementSchema;
+}
 
 /** The file's bytes, from the start, every time it is called. */
 export type BackupSource = () => AsyncIterable<Uint8Array>;
@@ -69,8 +80,12 @@ export interface StreamedBackup {
   ): Promise<void>;
 }
 
-function parseMeasurement(element: unknown, index: number): BackupMeasurement {
-  const parsed = backupMeasurementSchema.safeParse(element);
+function parseMeasurement(
+  schema: MeasurementSchema,
+  element: unknown,
+  index: number,
+): BackupMeasurement {
+  const parsed = schema.safeParse(element);
   if (!parsed.success) {
     const issue = parsed.error.issues[0];
     throw new StreamedBackupInvalidError(
@@ -98,6 +113,7 @@ export async function readStreamedBackup(
   source: BackupSource,
   options: ReadStreamedBackupOptions = {},
 ): Promise<StreamedBackup> {
+  const schema = await loadMeasurementSchema();
   let firstWithoutId: number | null = null;
   let bytes = 0;
   const keys = new BackupKeyIdCollector();
@@ -110,7 +126,7 @@ export async function readStreamedBackup(
   const { document, streamedCounts } = await scanBackupJson(counted(), {
     streamKeys: STREAMED,
     onElement: (_key, element, index) => {
-      const row = parseMeasurement(element, index);
+      const row = parseMeasurement(schema, element, index);
       if (!row.id && firstWithoutId === null) firstWithoutId = index;
       keys.visit(element, MEASUREMENTS);
       options.onMeasurementChecked?.(index + 1);
@@ -146,7 +162,7 @@ export async function readStreamedBackup(
         streamKeys: STREAMED,
         skipKeys,
         onElement: async (_key, element, index) => {
-          batch.push(parseMeasurement(element, index));
+          batch.push(parseMeasurement(schema, element, index));
           if (batch.length >= size) {
             const full = batch;
             batch = [];
diff --git a/src/lib/jobs/__tests__/offhost-backup.test.ts b/src/lib/jobs/__tests__/offhost-backup.test.ts
index 95702c8c7..368b4c2d5 100644
--- a/src/lib/jobs/__tests__/offhost-backup.test.ts
+++ b/src/lib/jobs/__tests__/offhost-backup.test.ts
@@ -2,10 +2,8 @@ import { createCipheriv, randomBytes } from "node:crypto";
 import type { Readable } from "node:stream";
 
 import { describe, it, expect, beforeEach, vi } from "vitest";
-import {
-  BACKUP_SCHEMA_VERSION,
-  backupPayloadSchema,
-} from "@/lib/validations/backup";
+import { backupPayloadSchema } from "@/lib/validations/backup";
+import { BACKUP_SCHEMA_VERSION } from "@/lib/validations/backup-summary";
 
 const mocks = vi.hoisted(() => ({
   buildFullBackupPayload: vi.fn(),
diff --git a/src/lib/validations/__tests__/backup.test.ts b/src/lib/validations/__tests__/backup.test.ts
index c10d46e65..fd037786f 100644
--- a/src/lib/validations/__tests__/backup.test.ts
+++ b/src/lib/validations/__tests__/backup.test.ts
@@ -18,12 +18,8 @@
  * of bubbling out of `prisma.createMany` with a useless message.
  */
 import { describe, expect, it } from "vitest";
-import {
-  backupPayloadSchema,
-  isCompatibleSchemaVersion,
-  parseBackupPayload,
-  summarizeBackup,
-} from "../backup";
+import { backupPayloadSchema, parseBackupPayload } from "../backup";
+import { isCompatibleSchemaVersion, summarizeBackup } from "../backup-summary";
 
 const baseEntry = {
   date: "2026-05-08",
diff --git a/src/lib/validations/backup-summary.ts b/src/lib/validations/backup-summary.ts
new file mode 100644
index 000000000..cd04d0eae
--- /dev/null
+++ b/src/lib/validations/backup-summary.ts
@@ -0,0 +1,216 @@
+/**
+ * What a backup is, without the schema that checks one.
+ *
+ * `backupPayloadSchema` (`backup.ts`) is the largest Zod tree in the server:
+ * built at import, it holds about 12 MB of heap. Everything here is what the
+ * backup paths need besides that check: the schema version, whether a file's
+ * version is one this server reads, and the per-section counts of a payload
+ * that has already been parsed. Importing this module never builds the
+ * schema, so a module on the boot path (the restore job, the stored-backup
+ * readers, the export writer) can import it freely and load `backup.ts` with
+ * a dynamic `import()` at the moment a file is actually validated.
+ */
+import type { BackupPayload } from "@/lib/validations/backup";
+
+export const BACKUP_SCHEMA_VERSION = "2" as const;
+export const LEGACY_BACKUP_SCHEMA_VERSION = "1" as const;
+
+/**
+ * Numeric counts of each backed-up record kind. Returned in the
+ * upload + restore API responses so the admin sees what they
+ * uploaded/restored without having to download the file again.
+ */
+export interface BackupSummary {
+  schemaVersion: string;
+  userId: string;
+  exportedAt: string;
+  measurements: number;
+  medications: number;
+  intakeEvents: number;
+  /** Side effects recorded against a drug, across every medication. */
+  medicationSideEffects: number;
+  /** Pinned efficacy targets, across every medication. */
+  medicationEfficacyTargets: number;
+  /** Archived schedule eras, across every medication. */
+  medicationScheduleRevisions: number;
+  moodEntries: number;
+  /** v1.15.0 — observed cycle spans in the backup. */
+  cycles: number;
+  /** v1.15.0 — cycle day-logs in the backup. */
+  cycleDayLogs: number;
+  /** Lab results in the backup. */
+  labResults: number;
+  nutrientDays: number;
+  /** User-scoped biomarker catalog entries in the backup. */
+  biomarkers: number;
+  /** Illness episodes, including flares/exacerbations. */
+  illnessEpisodes: number;
+  /** Illness day-logs across every episode. */
+  illnessDayLogs: number;
+  /** Allergy/intolerance records in the backup. */
+  allergies: number;
+  /** Family-history entries in the backup. */
+  familyHistory: number;
+  /** Workout summary records in the backup. */
+  workouts: number;
+  /** Document records (ciphertext included in canonical DR payloads). */
+  documents: number;
+  /** Which documents were filed against which condition. */
+  documentConditionLinks: number;
+  /** Facts staged out of a document, with their review decision. */
+  extractedFacts: number;
+  /** 1 when the account's durable self-context rides the file, 0 otherwise. */
+  healthProfile: number;
+  /** Effective-dated structured health-profile revisions. */
+  healthProfileFactRevisions: number;
+  /** Metrics the account defined itself. */
+  customMetrics: number;
+  /** Readings across every user-defined metric. */
+  customMetricEntries: number;
+  /** Persisted accepted correlation identities and dismissal decisions. */
+  correlationPatterns: number;
+  /** Stored day curves for the cumulative metrics, across every metric. */
+  intradayProfiles: number;
+  /** Local days whose health score was written down as it was shown. */
+  healthScoreRecords: number;
+  /** 1 when the record's setup answers ride the file, 0 otherwise. */
+  onboardingRecords: number;
+  /** v1.37.19 (A6-8) — the visit address book. */
+  practitioners: number;
+  /** v1.37.19 (A6-8) — doctor visits, planned and past. */
+  encounters: number;
+  /** v1.37.19 (A6-8) — the three encounter link tables, summed. */
+  encounterLinks: number;
+  /** v1.37.19 (A6-8) — immunization log entries. */
+  vaccinations: number;
+  /** v1.37.19 (A6-8) — vaccination↔document links. */
+  vaccinationLinks: number;
+  /** v1.37.20 (#223 / iOS #68) — Vorsorge reminder cadences. */
+  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;
+  /** Durable facts, agreed plans and things to bring back up. */
+  coachFacts: number;
+  coachPlans: number;
+  coachReminders: number;
+  /** Completed screener administrations. Disaster-recovery payloads only. */
+  mentalHealthAssessments: number;
+  /** Consent records. Disaster-recovery payloads only. */
+  consentReceipts: number;
+  /** Personal bests across every metric and sport slot. */
+  personalRecords: number;
+  /** Badges the account has unlocked, each with the day it was earned. */
+  userAchievements: number;
+  /** Local days with an environmental reading. */
+  environmentContexts: number;
+  /** Declared stretches spent away from home. */
+  environmentTravelLocations: number;
+  /** ECG strips, with their rhythm verdict and their trace. */
+  ecgRecordings: number;
+}
+
+export function summarizeBackup(payload: BackupPayload): BackupSummary {
+  return {
+    schemaVersion: payload.schemaVersion,
+    userId: payload.userId,
+    exportedAt: payload.exportedAt,
+    measurements: payload.measurements.length,
+    medications: payload.medications.length,
+    intakeEvents: payload.intakeEvents.length,
+    medicationSideEffects: payload.medications.reduce(
+      (sum, medication) => sum + medication.sideEffects.length,
+      0,
+    ),
+    medicationEfficacyTargets: payload.medications.reduce(
+      (sum, medication) => sum + medication.efficacyTargets.length,
+      0,
+    ),
+    medicationScheduleRevisions: payload.medications.reduce(
+      (sum, medication) => sum + medication.scheduleRevisions.length,
+      0,
+    ),
+    moodEntries: payload.moodEntries.length,
+    cycles: payload.cycles.length,
+    cycleDayLogs: payload.cycleDayLogs.length,
+    nutrientDays: payload.nutrientDays.length,
+    labResults: payload.labResults.length,
+    biomarkers: payload.biomarkers.length,
+    illnessEpisodes: payload.illnessEpisodes.length,
+    illnessDayLogs: payload.illnessEpisodes.reduce(
+      (sum, e) => sum + e.dayLogs.length,
+      0,
+    ),
+    allergies: payload.allergies.length,
+    familyHistory: payload.familyHistory.length,
+    workouts: payload.workouts.length,
+    documents: payload.documents.length,
+    // Counted from the release that carries them, so the admin's "what did I
+    // just restore" answer never under-counts a filed vault the way it once
+    // did for visits.
+    documentConditionLinks: payload.documentConditionLinks.length,
+    extractedFacts: payload.extractedFacts.length,
+    healthProfile: payload.healthProfile ? 1 : 0,
+    healthProfileFactRevisions: payload.healthProfileFacts.length,
+    customMetrics: payload.customMetrics.length,
+    customMetricEntries: payload.customMetrics.reduce(
+      (sum, metric) => sum + metric.entries.length,
+      0,
+    ),
+    correlationPatterns: payload.correlationPatterns.length,
+    intradayProfiles: payload.intradayProfiles.length,
+    healthScoreRecords: payload.healthScoreRecords.length,
+    onboardingRecords: payload.onboardingRecord ? 1 : 0,
+    // v1.37.19 (A6-8) — the sections restored since 08-01 were written and
+    // restored but absent from this report, so the admin's "what did I just
+    // restore" answer silently under-counted a file that carried visits or
+    // an Impfpass.
+    practitioners: payload.practitioners.length,
+    encounters: payload.encounters.length,
+    encounterLinks:
+      payload.encounterDocumentLinks.length +
+      payload.encounterLabLinks.length +
+      payload.encounterConditionLinks.length,
+    vaccinations: payload.vaccinations.length,
+    vaccinationLinks: payload.vaccinationDocumentLinks.length,
+    // v1.37.20 (#223 / iOS #68) — counted from the release that carries them,
+    // so the admin's "what did I just restore" answer never under-counts a
+    // 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,
+    ),
+    coachFacts: payload.coachFacts.length,
+    coachPlans: payload.coachPlans.length,
+    coachReminders: payload.coachReminders.length,
+    mentalHealthAssessments: payload.mentalHealthAssessments.length,
+    consentReceipts: payload.consentReceipts.length,
+    // Counted from the release that carries them, so the admin's "what did I
+    // just restore" answer never under-counts a file with bests, badges or an
+    // environmental history the way it once did for visits.
+    personalRecords: payload.personalRecords.length,
+    userAchievements: payload.userAchievements.length,
+    environmentContexts: payload.environmentContexts.length,
+    environmentTravelLocations: payload.environmentTravelLocations.length,
+    ecgRecordings: payload.ecgRecordings.length,
+  };
+}
+
+/**
+ * The schemaVersion the system understands today. Used by the upload
+ * route to reject inbound files written by a *future* HealthLog instance
+ * — restoring them under the current code might silently drop data the
+ * new shape carried.
+ */
+export function isCompatibleSchemaVersion(version: string): boolean {
+  return (
+    version === LEGACY_BACKUP_SCHEMA_VERSION ||
+    version === BACKUP_SCHEMA_VERSION
+  );
+}
diff --git a/src/lib/validations/backup.ts b/src/lib/validations/backup.ts
index f0a31c31f..e47df648e 100644
--- a/src/lib/validations/backup.ts
+++ b/src/lib/validations/backup.ts
@@ -88,14 +88,15 @@ import {
   DOCUMENT_SOURCE_SYSTEMS,
 } from "@/lib/validations/inbound-documents";
 import { REMINDER_EVENT_SOURCES } from "@/lib/measurement-reminders/satisfy";
+import {
+  BACKUP_SCHEMA_VERSION,
+  LEGACY_BACKUP_SCHEMA_VERSION,
+} from "@/lib/validations/backup-summary";
 import {
   UNITS_PER_DOSE_MESSAGE,
   isSupportedUnitsPerDose,
 } from "@/lib/medications/units-per-dose";
 
-export const BACKUP_SCHEMA_VERSION = "2" as const;
-const LEGACY_BACKUP_SCHEMA_VERSION = "1" as const;
-
 const isoDateTime = z
   .string()
   .min(1)
@@ -2078,193 +2079,6 @@ export type BackupPayload = z.infer<typeof backupPayloadSchema>;
 export const backupMeasurementSchema = measurementSchema;
 export type BackupMeasurement = z.infer<typeof measurementSchema>;
 
-/**
- * Numeric counts of each backed-up record kind. Returned in the
- * upload + restore API responses so the admin sees what they
- * uploaded/restored without having to download the file again.
- */
-export interface BackupSummary {
-  schemaVersion: string;
-  userId: string;
-  exportedAt: string;
-  measurements: number;
-  medications: number;
-  intakeEvents: number;
-  /** Side effects recorded against a drug, across every medication. */
-  medicationSideEffects: number;
-  /** Pinned efficacy targets, across every medication. */
-  medicationEfficacyTargets: number;
-  /** Archived schedule eras, across every medication. */
-  medicationScheduleRevisions: number;
-  moodEntries: number;
-  /** v1.15.0 — observed cycle spans in the backup. */
-  cycles: number;
-  /** v1.15.0 — cycle day-logs in the backup. */
-  cycleDayLogs: number;
-  /** Lab results in the backup. */
-  labResults: number;
-  nutrientDays: number;
-  /** User-scoped biomarker catalog entries in the backup. */
-  biomarkers: number;
-  /** Illness episodes, including flares/exacerbations. */
-  illnessEpisodes: number;
-  /** Illness day-logs across every episode. */
-  illnessDayLogs: number;
-  /** Allergy/intolerance records in the backup. */
-  allergies: number;
-  /** Family-history entries in the backup. */
-  familyHistory: number;
-  /** Workout summary records in the backup. */
-  workouts: number;
-  /** Document records (ciphertext included in canonical DR payloads). */
-  documents: number;
-  /** Which documents were filed against which condition. */
-  documentConditionLinks: number;
-  /** Facts staged out of a document, with their review decision. */
-  extractedFacts: number;
-  /** 1 when the account's durable self-context rides the file, 0 otherwise. */
-  healthProfile: number;
-  /** Effective-dated structured health-profile revisions. */
-  healthProfileFactRevisions: number;
-  /** Metrics the account defined itself. */
-  customMetrics: number;
-  /** Readings across every user-defined metric. */
-  customMetricEntries: number;
-  /** Persisted accepted correlation identities and dismissal decisions. */
-  correlationPatterns: number;
-  /** Stored day curves for the cumulative metrics, across every metric. */
-  intradayProfiles: number;
-  /** Local days whose health score was written down as it was shown. */
-  healthScoreRecords: number;
-  /** 1 when the record's setup answers ride the file, 0 otherwise. */
-  onboardingRecords: number;
-  /** v1.37.19 (A6-8) — the visit address book. */
-  practitioners: number;
-  /** v1.37.19 (A6-8) — doctor visits, planned and past. */
-  encounters: number;
-  /** v1.37.19 (A6-8) — the three encounter link tables, summed. */
-  encounterLinks: number;
-  /** v1.37.19 (A6-8) — immunization log entries. */
-  vaccinations: number;
-  /** v1.37.19 (A6-8) — vaccination↔document links. */
-  vaccinationLinks: number;
-  /** v1.37.20 (#223 / iOS #68) — Vorsorge reminder cadences. */
-  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;
-  /** Durable facts, agreed plans and things to bring back up. */
-  coachFacts: number;
-  coachPlans: number;
-  coachReminders: number;
-  /** Completed screener administrations. Disaster-recovery payloads only. */
-  mentalHealthAssessments: number;
-  /** Consent records. Disaster-recovery payloads only. */
-  consentReceipts: number;
-  /** Personal bests across every metric and sport slot. */
-  personalRecords: number;
-  /** Badges the account has unlocked, each with the day it was earned. */
-  userAchievements: number;
-  /** Local days with an environmental reading. */
-  environmentContexts: number;
-  /** Declared stretches spent away from home. */
-  environmentTravelLocations: number;
-  /** ECG strips, with their rhythm verdict and their trace. */
-  ecgRecordings: number;
-}
-
-export function summarizeBackup(payload: BackupPayload): BackupSummary {
-  return {
-    schemaVersion: payload.schemaVersion,
-    userId: payload.userId,
-    exportedAt: payload.exportedAt,
-    measurements: payload.measurements.length,
-    medications: payload.medications.length,
-    intakeEvents: payload.intakeEvents.length,
-    medicationSideEffects: payload.medications.reduce(
-      (sum, medication) => sum + medication.sideEffects.length,
-      0,
-    ),
-    medicationEfficacyTargets: payload.medications.reduce(
-      (sum, medication) => sum + medication.efficacyTargets.length,
-      0,
-    ),
-    medicationScheduleRevisions: payload.medications.reduce(
-      (sum, medication) => sum + medication.scheduleRevisions.length,
-      0,
-    ),
-    moodEntries: payload.moodEntries.length,
-    cycles: payload.cycles.length,
-    cycleDayLogs: payload.cycleDayLogs.length,
-    nutrientDays: payload.nutrientDays.length,
-    labResults: payload.labResults.length,
-    biomarkers: payload.biomarkers.length,
-    illnessEpisodes: payload.illnessEpisodes.length,
-    illnessDayLogs: payload.illnessEpisodes.reduce(
-      (sum, e) => sum + e.dayLogs.length,
-      0,
-    ),
-    allergies: payload.allergies.length,
-    familyHistory: payload.familyHistory.length,
-    workouts: payload.workouts.length,
-    documents: payload.documents.length,
-    // Counted from the release that carries them, so the admin's "what did I
-    // just restore" answer never under-counts a filed vault the way it once
-    // did for visits.
-    documentConditionLinks: payload.documentConditionLinks.length,
-    extractedFacts: payload.extractedFacts.length,
-    healthProfile: payload.healthProfile ? 1 : 0,
-    healthProfileFactRevisions: payload.healthProfileFacts.length,
-    customMetrics: payload.customMetrics.length,
-    customMetricEntries: payload.customMetrics.reduce(
-      (sum, metric) => sum + metric.entries.length,
-      0,
-    ),
-    correlationPatterns: payload.correlationPatterns.length,
-    intradayProfiles: payload.intradayProfiles.length,
-    healthScoreRecords: payload.healthScoreRecords.length,
-    onboardingRecords: payload.onboardingRecord ? 1 : 0,
-    // v1.37.19 (A6-8) — the sections restored since 08-01 were written and
-    // restored but absent from this report, so the admin's "what did I just
-    // restore" answer silently under-counted a file that carried visits or
-    // an Impfpass.
-    practitioners: payload.practitioners.length,
-    encounters: payload.encounters.length,
-    encounterLinks:
-      payload.encounterDocumentLinks.length +
-      payload.encounterLabLinks.length +
-      payload.encounterConditionLinks.length,
-    vaccinations: payload.vaccinations.length,
-    vaccinationLinks: payload.vaccinationDocumentLinks.length,
-    // v1.37.20 (#223 / iOS #68) — counted from the release that carries them,
-    // so the admin's "what did I just restore" answer never under-counts a
-    // 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,
-    ),
-    coachFacts: payload.coachFacts.length,
-    coachPlans: payload.coachPlans.length,
-    coachReminders: payload.coachReminders.length,
-    mentalHealthAssessments: payload.mentalHealthAssessments.length,
-    consentReceipts: payload.consentReceipts.length,
-    // Counted from the release that carries them, so the admin's "what did I
-    // just restore" answer never under-counts a file with bests, badges or an
-    // environmental history the way it once did for visits.
-    personalRecords: payload.personalRecords.length,
-    userAchievements: payload.userAchievements.length,
-    environmentContexts: payload.environmentContexts.length,
-    environmentTravelLocations: payload.environmentTravelLocations.length,
-    ecgRecordings: payload.ecgRecordings.length,
-  };
-}
-
 /**
  * Parse a JSON blob (string or already-parsed object) against
  * `backupPayloadSchema`, returning a typed payload. Throws ZodError on
@@ -2280,16 +2094,3 @@ export function parseBackupPayload(input: string | unknown): BackupPayload {
   const raw = typeof input === "string" ? JSON.parse(input) : input;
   return backupPayloadSchema.parse(raw);
 }
-
-/**
- * The schemaVersion the system understands today. Used by the upload
- * route to reject inbound files written by a *future* HealthLog instance
- * — restoring them under the current code might silently drop data the
- * new shape carried.
- */
-export function isCompatibleSchemaVersion(version: string): boolean {
-  return (
-    version === LEGACY_BACKUP_SCHEMA_VERSION ||
-    version === BACKUP_SCHEMA_VERSION
-  );
-}
diff --git a/tests/integration/backup-preview.test.ts b/tests/integration/backup-preview.test.ts
index f7d984af0..81757c6c7 100644
--- a/tests/integration/backup-preview.test.ts
+++ b/tests/integration/backup-preview.test.ts
@@ -126,8 +126,8 @@ async function preview(id: string) {
 
 /** The counts a full read of the stored copy gives: the old preview. */
 async function fullReadSummary(id: string) {
-  const { parseBackupPayload, summarizeBackup } =
-    await import("@/lib/validations/backup");
+  const { parseBackupPayload } = await import("@/lib/validations/backup");
+  const { summarizeBackup } = await import("@/lib/validations/backup-summary");
   const opensBefore = opened.count;
   const payload = parseBackupPayload(
     JSON.parse(await readStoredBackup(getPrismaClient(), id)),
diff --git a/tests/integration/backup-round-trip.test.ts b/tests/integration/backup-round-trip.test.ts
index 6314593f5..045447121 100644
--- a/tests/integration/backup-round-trip.test.ts
+++ b/tests/integration/backup-round-trip.test.ts
@@ -79,7 +79,8 @@ import { legacyStreamedBlobFrom } from "@/__tests__/helpers/legacy-backup-blob";
 import { streamFullBackupJson } from "@/lib/export/full-backup-stream";
 import { BackupKeyIdCollector } from "@/lib/export/backup-key-ids";
 import { createBackupPreviewCollector } from "@/lib/export/backup-preview";
-import { parseBackupPayload, summarizeBackup } from "@/lib/validations/backup";
+import { parseBackupPayload } from "@/lib/validations/backup";
+import { summarizeBackup } from "@/lib/validations/backup-summary";
 import {
   TWO_ENDED_MODELS,
   USER_COLUMN_BACKUP_CLASS,