diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index f0241e651..30b9cbc17 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -2363,8 +2363,10 @@ paths:
       tags:
         - Measurements
       summary: Delete measurements by external ID (iOS deletion-sync)
-      description: Removes the user's measurement rows whose externalId is in the request list. Rows owned by another user are
-        silently skipped (cross-user 404 guard). Up to 500 externalIds per call.
+      description: "Removes the user's HealthKit-ingested measurement rows (source `APPLE_HEALTH`) whose externalId is in the
+        request list. Only app-minted rows are eligible: an externalId that maps to an integration- or manually-sourced
+        row (a colliding externalUUID) is a no-op, never a delete. Rows owned by another user are silently skipped
+        (cross-user 404 guard). Up to 500 externalIds per call."
       requestBody:
         required: true
         content:
diff --git a/src/app/api/measurements/by-external-ids/__tests__/route.test.ts b/src/app/api/measurements/by-external-ids/__tests__/route.test.ts
new file mode 100644
index 000000000..c618a6bc8
--- /dev/null
+++ b/src/app/api/measurements/by-external-ids/__tests__/route.test.ts
@@ -0,0 +1,157 @@
+/**
+ * DELETE /api/measurements/by-external-ids — iOS HealthKit deletion-sync.
+ *
+ * Asserts the origin-scoped soft-delete contract (v1.25, iOS #35): the
+ * reconciliation only tombstones rows the app minted through its HealthKit
+ * ingestion path (`source = APPLE_HEALTH`). A foreign-origin externalId — one
+ * that collides with an integration- or manually-sourced row — is excluded by
+ * the source predicate and is a silent no-op, never a delete. Cross-user and
+ * idempotency guards stay as before.
+ */
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest } from "next/server";
+
+vi.mock("@/lib/db", () => ({
+  prisma: {
+    measurement: {
+      findMany: vi.fn(),
+      updateMany: vi.fn(),
+    },
+    auditLog: { create: vi.fn() },
+  },
+}));
+
+vi.mock("@/lib/auth/session", () => ({ getSession: vi.fn() }));
+vi.mock("@/lib/auth/audit", () => ({
+  auditLog: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("@/lib/cache/invalidate", () => ({
+  invalidateUserMeasurements: vi.fn(),
+}));
+vi.mock("@/lib/insights/comprehensive-generate", () => ({
+  invalidateStatusInsightsForTypes: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("@/lib/rollups/measurement-rollups", async () => {
+  const actual = await vi.importActual<
+    typeof import("@/lib/rollups/measurement-rollups")
+  >("@/lib/rollups/measurement-rollups");
+  return {
+    collapseToTypeDayKeys: actual.collapseToTypeDayKeys,
+    recomputeBucketsForMeasurement: vi.fn().mockResolvedValue(undefined),
+  };
+});
+vi.mock("@/lib/logging/transports", () => ({ emitIfSampled: vi.fn() }));
+vi.mock("@/lib/db-compat", () => ({
+  ensureDbCompatibility: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("next/headers", () => ({
+  headers: vi.fn(async () => ({ get: () => null })),
+  cookies: vi.fn(async () => ({
+    get: () => undefined,
+    set: () => {},
+    delete: () => {},
+  })),
+}));
+
+import { DELETE } from "../route";
+import { prisma } from "@/lib/db";
+import { getSession } from "@/lib/auth/session";
+import { invalidateUserMeasurements } from "@/lib/cache/invalidate";
+import { invalidateStatusInsightsForTypes } from "@/lib/insights/comprehensive-generate";
+import { recomputeBucketsForMeasurement } from "@/lib/rollups/measurement-rollups";
+
+const SESSION_OK = {
+  session: { id: "sess-1", expiresAt: new Date(Date.now() + 3_600_000) },
+  user: { id: "user-1", username: "tester", role: "USER" as const },
+};
+
+function delReq(body: unknown): NextRequest {
+  return new NextRequest("http://localhost/api/measurements/by-external-ids", {
+    method: "DELETE",
+    headers: { "content-type": "application/json" },
+    body: JSON.stringify(body),
+  });
+}
+
+beforeEach(() => {
+  vi.resetAllMocks();
+  vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+  vi.mocked(prisma.auditLog.create).mockResolvedValue({} as never);
+  vi.mocked(recomputeBucketsForMeasurement).mockResolvedValue(undefined);
+  vi.mocked(invalidateStatusInsightsForTypes).mockResolvedValue(undefined);
+});
+
+describe("DELETE /api/measurements/by-external-ids", () => {
+  it("scopes both the pre-fetch and the soft-delete to the app-minted APPLE_HEALTH source", async () => {
+    vi.mocked(prisma.measurement.findMany).mockResolvedValue([
+      { type: "WEIGHT", measuredAt: new Date("2026-01-01T08:00:00Z") },
+    ] as never);
+    vi.mocked(prisma.measurement.updateMany).mockResolvedValue({
+      count: 1,
+    } as never);
+
+    const res = await DELETE(delReq({ externalIds: ["uuid-aaa"] }));
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as { data: { deletedCount: number } };
+    expect(body.data.deletedCount).toBe(1);
+
+    const findWhere = vi.mocked(prisma.measurement.findMany).mock.calls[0]![0]!
+      .where;
+    expect(findWhere).toMatchObject({
+      userId: "user-1",
+      source: "APPLE_HEALTH",
+      externalId: { in: ["uuid-aaa"] },
+      deletedAt: null,
+    });
+
+    const updateWhere = vi.mocked(prisma.measurement.updateMany).mock
+      .calls[0]![0].where;
+    expect(updateWhere).toMatchObject({
+      userId: "user-1",
+      source: "APPLE_HEALTH",
+      externalId: { in: ["uuid-aaa"] },
+      deletedAt: null,
+    });
+  });
+
+  it("is a no-op for a foreign-origin externalId that collides on a non-app-minted row", async () => {
+    // The caller's reconciliation list carries an externalId that, on the
+    // server, maps to a WITHINGS-sourced row (a colliding externalUUID). The
+    // `source = APPLE_HEALTH` predicate excludes it, so the pre-fetch and the
+    // soft-delete both match zero rows.
+    vi.mocked(prisma.measurement.findMany).mockResolvedValue([] as never);
+    vi.mocked(prisma.measurement.updateMany).mockResolvedValue({
+      count: 0,
+    } as never);
+
+    const res = await DELETE(delReq({ externalIds: ["withings-collision"] }));
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as { data: { deletedCount: number } };
+    expect(body.data.deletedCount).toBe(0);
+
+    // The delete was still source-scoped (the foreign row was never eligible).
+    const updateWhere = vi.mocked(prisma.measurement.updateMany).mock
+      .calls[0]![0].where;
+    expect(updateWhere).toMatchObject({ source: "APPLE_HEALTH" });
+
+    // Zero deletions → no cache eviction, no rollup recompute, no insight bust.
+    expect(invalidateUserMeasurements).not.toHaveBeenCalled();
+    expect(recomputeBucketsForMeasurement).not.toHaveBeenCalled();
+    expect(invalidateStatusInsightsForTypes).not.toHaveBeenCalled();
+  });
+
+  it("returns deletedCount 0 with 200 for an empty externalIds array", async () => {
+    const res = await DELETE(delReq({ externalIds: [] }));
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as { data: { deletedCount: number } };
+    expect(body.data.deletedCount).toBe(0);
+    expect(prisma.measurement.updateMany).not.toHaveBeenCalled();
+  });
+
+  it("rejects a batch over the 500-id cap with 422", async () => {
+    const externalIds = Array.from({ length: 501 }, (_, i) => `uuid-${i}`);
+    const res = await DELETE(delReq({ externalIds }));
+    expect(res.status).toBe(422);
+    expect(prisma.measurement.updateMany).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/app/api/measurements/by-external-ids/route.ts b/src/app/api/measurements/by-external-ids/route.ts
index 9c07d6a53..9914cb12b 100644
--- a/src/app/api/measurements/by-external-ids/route.ts
+++ b/src/app/api/measurements/by-external-ids/route.ts
@@ -10,6 +10,13 @@
  * rather than removing the row, so deletions surface as tombstones on the
  * `/api/sync/changes` delta feed).
  *
+ * Origin scope (v1.25, iOS #35): the delete only touches rows the iOS
+ * client minted through its HealthKit ingestion path (`source =
+ * APPLE_HEALTH`). An externalId the app never minted — an integration- or
+ * manually-sourced row that happens to collide on externalUUID — is a
+ * no-op, never a delete. Defence-in-depth so a foreign HealthKit sample
+ * with a colliding UUID cannot be tombstoned by this reconciliation.
+ *
  * Idempotency contract:
  *   - Cross-user safety: rows owned by another user are silently skipped
  *     (Prisma's `updateMany` with `userId` in the where-clause guarantees
@@ -105,9 +112,21 @@ async function deleteByExternalIds(request: NextRequest): Promise<Response> {
   // tombstoned by this call. We pre-fetch the (type, measuredAt) tuples
   // of the live matches so the rollup recompute below knows which
   // buckets to refresh.
+  //
+  // v1.25 (iOS #35) — scope to the app's HealthKit ingestion source
+  // (`APPLE_HEALTH`). This reconciliation removes HealthKit samples the
+  // iOS client minted; only `source = APPLE_HEALTH` rows are app-minted on
+  // this path. Defence-in-depth against a colliding externalId: an
+  // integration- or manually-sourced row (WITHINGS / OURA / MANUAL / …)
+  // that happens to share an externalUUID with a now-absent HealthKit
+  // sample is NOT app-minted, so it falls outside the predicate and the
+  // delete is a no-op for it rather than tombstoning a foreign-origin row.
+  const APP_MINTED_SOURCE = "APPLE_HEALTH" as const;
+
   const affectedRows = await prisma.measurement.findMany({
     where: {
       userId: user.id,
+      source: APP_MINTED_SOURCE,
       externalId: { in: externalIds },
       deletedAt: null,
     },
@@ -117,6 +136,7 @@ async function deleteByExternalIds(request: NextRequest): Promise<Response> {
   const result = await prisma.measurement.updateMany({
     where: {
       userId: user.id,
+      source: APP_MINTED_SOURCE,
       externalId: { in: externalIds },
       deletedAt: null,
     },
diff --git a/src/lib/openapi/routes/measurements.ts b/src/lib/openapi/routes/measurements.ts
index 650d157f8..09aab36be 100644
--- a/src/lib/openapi/routes/measurements.ts
+++ b/src/lib/openapi/routes/measurements.ts
@@ -638,7 +638,7 @@ export const measurementPaths: NonNullable<ZodOpenApiObject["paths"]> = {
       tags: ["Measurements"],
       summary: "Delete measurements by external ID (iOS deletion-sync)",
       description:
-        "Removes the user's measurement rows whose externalId is in the request list. Rows owned by another user are silently skipped (cross-user 404 guard). Up to 500 externalIds per call.",
+        "Removes the user's HealthKit-ingested measurement rows (source `APPLE_HEALTH`) whose externalId is in the request list. Only app-minted rows are eligible: an externalId that maps to an integration- or manually-sourced row (a colliding externalUUID) is a no-op, never a delete. Rows owned by another user are silently skipped (cross-user 404 guard). Up to 500 externalIds per call.",
       requestBody: {
         required: true,
         content: {