fix(medications): keep an extra Apple Health dose off a slot that already holds one

A HealthKit dose event binds to a slot by window band, and a weekly
schedule's band reaches a day either side of its slot. An extra dose
logged the day after a scheduled one landed on that slot and overwrote it
last-write-wins: the slot's time changed and the extra dose was stored
nowhere. An external dose record whose band slot already carries a
different take is now recorded as its own unscheduled dose.

The dose history now lets the take stored on a slot claim it before an
extra dose stored on its own instant, instead of following the order the
rows were read in, so the extra dose reads as off-schedule.

src/app/api/medications/intake/bulk/__tests__/route.test.ts

@@ -1380,9 +1380,11 @@ describe("POST /api/medications/intake/bulk — v1.28 Apple Health dose events",
   });
 
   it("stamps the externalId onto the pending slot row when the Apple dose converges by band", async () => {
-    // Dedup pre-check first (empty), then the canonical-slot find returns
-    // the worker-minted pending REMINDER row for the 19:00 slot.
+    // Dedup pre-check first (empty), then the held-dose probe (no take on
+    // the slot yet), then the canonical-slot find returns the worker-minted
+    // pending REMINDER row for the 19:00 slot.
     vi.mocked(prisma.medicationIntakeEvent.findMany)
+      .mockResolvedValueOnce([] as never)
       .mockResolvedValueOnce([] as never)
       .mockResolvedValueOnce([
         {

src/app/api/medications/intake/bulk/route.ts

@@ -65,6 +65,7 @@ import {
   resolveForcedSlotForWrite,
   resolveSlotForWriteByBand,
   resolveSlotInstantForWrite,
+  slotHeldByAnotherDose,
 } from "@/lib/medications/scheduling/slot-upsert";
 import { resolveInjectionSiteForWrite } from "@/lib/medications/injection-site-write";
 import {
@@ -338,6 +339,9 @@ async function postBulk(request: NextRequest): Promise<Response> {
   let inserted = 0;
   let updated = 0;
   let duplicates = 0;
+  // External dose records kept as their own unscheduled dose because their
+  // band slot already carried a different one.
+  let extraDosesUnscheduled = 0;
   const skipped: Array<{ index: number; reason: string }> = [];
   const unstableShapes: UnstableExternalIdShape[] = [];
   // v1.4.39 W-MED — collect distinct `(medicationId, dayKey)` pairs
@@ -443,6 +447,9 @@ async function postBulk(request: NextRequest): Promise<Response> {
       // a band decision. Pending echoes / skips carry no decision
       // (undefined → the upsert leaves an existing USER_PIN untouched).
       let attributionSource: "AUTO" | "USER_PIN" | undefined;
+      // Set when the band slot is held by a different dose and this take is
+      // recorded unscheduled; it must not converge onto any slot row below.
+      let heldByAnotherDose = false;
       if (isExplicitTaken && entry.forceSlotInstant !== undefined) {
         canonicalSlot = await resolveForcedSlotForWrite({
           userId: user.id,
@@ -486,6 +493,26 @@ async function postBulk(request: NextRequest): Promise<Response> {
         });
         canonicalSlot = attribution.slotInstant;
         attributionSource = "AUTO";
+        // An external dose record (a HealthKit dose event) whose band slot
+        // already carries a different recorded dose is an extra dose, not a
+        // correction of that one. Converging would overwrite the slot's
+        // take last-write-wins and the extra dose would exist nowhere; it is
+        // recorded as its own unscheduled dose instead.
+        if (
+          canonicalSlot !== null &&
+          entry.externalId !== undefined &&
+          (await slotHeldByAnotherDose({
+            userId: user.id,
+            medicationId: entry.medicationId,
+            canonicalSlot,
+            takenAt: entry.takenAt as Date,
+            externalId: entry.externalId,
+          }))
+        ) {
+          canonicalSlot = null;
+          heldByAnotherDose = true;
+          extraDosesUnscheduled += 1;
+        }
       } else if (isExplicitSkip && entry.scheduledFor === undefined) {
         // v1.16.9 — a slot-less deliberate skip resolves by band
         // membership on the skip moment, exactly like a take does. The
@@ -666,6 +693,7 @@ async function postBulk(request: NextRequest): Promise<Response> {
         // late-morning dose consuming the evening slot). It records
         // standalone (ad-hoc) instead.
         const existingSlotRow =
+          !heldByAnotherDose &&
           entry.scheduledFor !== undefined &&
           mayConvergeOntoSuppliedSlot({
             skipped: entry.skipped,
@@ -878,6 +906,7 @@ async function postBulk(request: NextRequest): Promise<Response> {
       updated,
       duplicates,
       skipped: skipped.length,
+      extra_doses_unscheduled: extraDosesUnscheduled,
       ...(unstableShapes.length > 0
         ? unstableExternalIdMeta("medication.intake.bulk", unstableShapes)
         : {}),