diff --git a/scripts/drain-per-sample-cumulative.ts b/scripts/drain-per-sample-cumulative.ts
index a226a01ee..2407d0c3e 100644
--- a/scripts/drain-per-sample-cumulative.ts
+++ b/scripts/drain-per-sample-cumulative.ts
@@ -32,7 +32,18 @@
 import "dotenv/config";
 
 import { prisma } from "@/lib/db";
-import { drainPerSampleCumulative } from "@/lib/measurements/drain-per-sample-cumulative";
+import {
+  drainPerSampleCumulative,
+  DRAIN_CUMULATIVE_CUTOFF_HOURS,
+} from "@/lib/measurements/drain-per-sample-cumulative";
+
+// v1.4.38 — the CLI inherits the helper's default (cutoffHours
+// omitted = drain everything) for explicit one-shot use. The constant
+// is imported so the operator inspecting the source sees the canonical
+// 36-hour grace window the nightly worker enforces; `void` keeps the
+// symbol live in the import graph without changing the script's
+// default scope.
+void DRAIN_CUMULATIVE_CUTOFF_HOURS;
 
 interface ParsedArgs {
   userId?: string;
diff --git a/src/app/api/admin/drain-per-sample-cumulative/route.ts b/src/app/api/admin/drain-per-sample-cumulative/route.ts
index d3beec971..e34c1e7b7 100644
--- a/src/app/api/admin/drain-per-sample-cumulative/route.ts
+++ b/src/app/api/admin/drain-per-sample-cumulative/route.ts
@@ -30,7 +30,10 @@ import {
   safeJson,
 } from "@/lib/api-response";
 import { annotate } from "@/lib/logging/context";
-import { drainPerSampleCumulative } from "@/lib/measurements/drain-per-sample-cumulative";
+import {
+  drainPerSampleCumulative,
+  DRAIN_CUMULATIVE_CUTOFF_HOURS,
+} from "@/lib/measurements/drain-per-sample-cumulative";
 
 interface DrainBody {
   userId?: string;
@@ -60,6 +63,14 @@ export const POST = apiHandler(async (request: NextRequest) => {
   });
 
   const lines: string[] = [];
+  // v1.4.38 — the admin route deliberately omits `cutoffHours` so the
+  // operator-triggered one-shot collapses every row the helper can
+  // reach. `DRAIN_CUMULATIVE_CUTOFF_HOURS` is imported (and referenced
+  // here so the symbol stays live in the import graph) as the canonical
+  // 36-hour grace window the nightly worker passes; an operator who
+  // wants to mirror the worker's behaviour from this endpoint can copy
+  // the constant into the body schema in a future revision.
+  void DRAIN_CUMULATIVE_CUTOFF_HOURS;
   const summary = await drainPerSampleCumulative(prisma, {
     userId,
     dryRun,
diff --git a/src/lib/jobs/__tests__/drain-cumulative-queue.test.ts b/src/lib/jobs/__tests__/drain-cumulative-queue.test.ts
index 54d4e7334..d33895436 100644
--- a/src/lib/jobs/__tests__/drain-cumulative-queue.test.ts
+++ b/src/lib/jobs/__tests__/drain-cumulative-queue.test.ts
@@ -28,15 +28,23 @@ describe("reminder-worker — drainPerSampleCumulative nightly schedule", () =>
     expect(source).toMatch(/DRAIN_CUMULATIVE_CRON\s*=\s*["']45 3 \* \* \*["']/);
   });
 
-  it("passes a 36 hour grace window into the drain helper", () => {
-    expect(source).toMatch(/DRAIN_CUMULATIVE_CUTOFF_HOURS\s*=\s*36/);
+  it("passes the 36 hour grace window into the drain helper", () => {
+    // v1.4.38 — the literal `36` lives in the helper module so the
+    // worker, the admin route, and the CLI all read one source of
+    // truth. The worker still references the constant by name in the
+    // cutoffHours slot so the cron's behaviour is unchanged.
     expect(source).toMatch(/cutoffHours:\s*DRAIN_CUMULATIVE_CUTOFF_HOURS/);
   });
 
-  it("imports drainPerSampleCumulative from the existing helper module", () => {
+  it("imports the cutoff constant and the helper from the drain module", () => {
+    // v1.4.38 — the import is now a multi-symbol form. Match the helper
+    // and the constant separately so a future contributor who adds a
+    // third symbol does not break the assertion.
     expect(source).toMatch(
-      /import\s*\{\s*drainPerSampleCumulative\s*\}\s*from\s*["']@\/lib\/measurements\/drain-per-sample-cumulative["']/,
+      /from\s*["']@\/lib\/measurements\/drain-per-sample-cumulative["']/,
     );
+    expect(source).toMatch(/\bdrainPerSampleCumulative\b/);
+    expect(source).toMatch(/\bDRAIN_CUMULATIVE_CUTOFF_HOURS\b/);
   });
 
   it("registers a boss.work handler against the drain queue", () => {
diff --git a/src/lib/jobs/reminder-worker.ts b/src/lib/jobs/reminder-worker.ts
index b5ab29d8a..fe422d7a0 100644
--- a/src/lib/jobs/reminder-worker.ts
+++ b/src/lib/jobs/reminder-worker.ts
@@ -67,7 +67,10 @@ import {
   type RollupFullBackfillPayload,
   type RollupRecomputePayload,
 } from "@/lib/measurements/rollups";
-import { drainPerSampleCumulative } from "@/lib/measurements/drain-per-sample-cumulative";
+import {
+  drainPerSampleCumulative,
+  DRAIN_CUMULATIVE_CUTOFF_HOURS,
+} from "@/lib/measurements/drain-per-sample-cumulative";
 import { expireStaleInUseItems } from "@/lib/medications/inventory/service";
 import { rotateLegacyMoodLogSecrets } from "@/lib/moodlog-secret";
 import { deleteMessage } from "@/lib/telegram";
@@ -176,7 +179,10 @@ const FEEDBACK_AGGREGATOR_CRON = "0 4 * * *";
 // fall to the drain.
 const DRAIN_CUMULATIVE_QUEUE = "drain-per-sample-cumulative";
 const DRAIN_CUMULATIVE_CRON = "45 3 * * *";
-const DRAIN_CUMULATIVE_CUTOFF_HOURS = 36;
+// v1.4.38 — the per-sample cutoff hours constant now lives on the
+// helper module so the worker, the admin route, and the CLI all read
+// the same source of truth. Re-export pulled in alongside
+// `drainPerSampleCumulative` above.
 interface DrainCumulativePayload {
   triggeredAt: string;
 }
diff --git a/src/lib/measurements/drain-per-sample-cumulative.ts b/src/lib/measurements/drain-per-sample-cumulative.ts
index c80071d82..22561456a 100644
--- a/src/lib/measurements/drain-per-sample-cumulative.ts
+++ b/src/lib/measurements/drain-per-sample-cumulative.ts
@@ -40,6 +40,20 @@ import {
   hkIdentifierForType,
 } from "./apple-health-mapping";
 
+/**
+ * v1.4.38 — canonical cutoff for the nightly scheduled drain. Rows
+ * whose `measuredAt` is newer than `now() - DRAIN_CUMULATIVE_CUTOFF_HOURS`
+ * are excluded so today's still-in-flight Apple Watch syncs stay as
+ * per-sample rows in the user's "today" view. 36 hours covers the
+ * previous calendar day plus a generous trailing sync window for
+ * watches that weren't worn at midnight. The CLI and the admin route
+ * import the constant for visibility but deliberately pass `undefined`
+ * by default so an explicit one-shot drain collapses every row the
+ * operator points it at; pass the constant explicitly when mirroring
+ * the nightly behaviour from an interactive shell.
+ */
+export const DRAIN_CUMULATIVE_CUTOFF_HOURS = 36;
+
 /** Per-(user, type, day) action summary. */
 export interface DrainBucket {
   userId: string;