feat(workouts): accept an optional HR series on the batch contract

Extend POST /api/workouts/batch with an optional per-workout `samples`
array — a route-independent heart-rate series so indoor workouts still
yield a strain-relevant signal. Each entry is `{ t, hr?, speedMs?,
power?, cadence? }`; the array is capped at 30 000 points
(MAX_WORKOUT_HR_SAMPLES), covering a long endurance session sampled at
1 Hz while bounding the largest new workout-side write stream the same
way the 20 000-point route cap bounds the geometry.

Persistence rides the existing route-attachment path: the freshly
written workout id is resolved once (by composite key, or the manual
tuple), then both the route geometry and the HR series attach by FK
with skipDuplicates so a re-submitted batch stays idempotent. A workout
may carry both a GPS route and a canonical HR series, or just one.

GET /api/workouts/{id} returns the series alongside the route. OpenAPI
regenerated.

`samples` keeps first-write-wins/overwrite parity with the workout row
it hangs off: the 1:1 FK plus skipDuplicates means a re-ingest of an
existing workout never duplicates or mutates its series.

src/app/api/workouts/[id]/route.ts

@@ -50,6 +50,12 @@ export const GET = apiHandler(
             createdAt: true,
           },
         },
+        samples: {
+          select: {
+            samples: true,
+            sampleCount: true,
+          },
+        },
       },
     });
 
@@ -108,6 +114,16 @@ export const GET = apiHandler(
         }
       : null;
 
+    // v1.10.0 — route-independent per-workout HR series. Present for
+    // both indoor (no route) and outdoor workouts that shipped a
+    // `samples` array on ingest; null otherwise.
+    const samples = row.samples
+      ? {
+          sampleCount: row.samples.sampleCount,
+          samples: row.samples.samples,
+        }
+      : null;
+
     return apiSuccess({
       id: row.id,
       sportType: row.sportType,
@@ -126,6 +142,7 @@ export const GET = apiHandler(
       externalId: row.externalId,
       metadata: row.metadata,
       route,
+      samples,
       // v1.4.32 — when the requested id is a non-canonical twin the
       // caller can redirect to `canonicalId` to land on the cluster
       // winner. `canonicalId === id` when the requested row already

src/app/api/workouts/__tests__/batch-create.test.ts

@@ -21,6 +21,9 @@ vi.mock("@/lib/db", () => ({
     workoutRoute: {
       createMany: vi.fn(),
     },
+    workoutSamples: {
+      createMany: vi.fn(),
+    },
     user: {
       findUnique: vi.fn(),
     },
@@ -123,6 +126,7 @@ beforeEach(() => {
   vi.mocked(prisma.workout.createMany).mockResolvedValue({ count: 0 });
   vi.mocked(prisma.workout.findFirst).mockResolvedValue(null);
   vi.mocked(prisma.workoutRoute.createMany).mockResolvedValue({ count: 0 });
+  vi.mocked(prisma.workoutSamples.createMany).mockResolvedValue({ count: 0 });
   // v1.4.43 W9 — default to no per-user source-priority override so
   // the write-time picker walks the canonical default ladder. Tests
   // that exercise a custom ladder override this in-line.
@@ -386,6 +390,122 @@ describe("POST /api/workouts/batch — nested route attachment", () => {
   });
 });
 
+describe("POST /api/workouts/batch — per-workout HR series (v1.10.0)", () => {
+  it("creates a WorkoutSamples row for an indoor workout (samples, no route)", async () => {
+    vi.mocked(prisma.workout.createMany).mockResolvedValue({ count: 1 });
+    vi.mocked(prisma.workout.findMany).mockImplementation((async (args: {
+      select?: { id?: true };
+    }) => {
+      if (args.select?.id) {
+        return [
+          {
+            id: "wkt-indoor-id",
+            source: "APPLE_HEALTH",
+            externalId: "uuid-indoor",
+          },
+        ];
+      }
+      return [];
+    }) as never);
+
+    const res = await POST(
+      makeRequest({
+        workouts: [
+          validWorkout("uuid-indoor", {
+            sportType: "strength",
+            samples: [
+              { t: "2026-05-14T06:30:00.000Z", hr: 110 },
+              { t: "2026-05-14T06:30:05.000Z", hr: 118 },
+              { t: "2026-05-14T06:30:10.000Z", hr: 124, power: 0, cadence: 0 },
+            ],
+          }),
+        ],
+      }),
+    );
+    expect(res.status).toBe(200);
+    // The route table is untouched — an indoor workout has no GPS route.
+    expect(prisma.workoutRoute.createMany).not.toHaveBeenCalled();
+    // The HR series lands in the dedicated child table by FK.
+    expect(prisma.workoutSamples.createMany).toHaveBeenCalledTimes(1);
+    const call = vi.mocked(prisma.workoutSamples.createMany).mock.calls[0]?.[0];
+    const rows = (
+      call as {
+        data: Array<{
+          workoutId: string;
+          sampleCount: number;
+          samples: unknown;
+        }>;
+      }
+    ).data;
+    expect(rows[0]?.workoutId).toBe("wkt-indoor-id");
+    // `sampleCount` is the denormalised series length.
+    expect(rows[0]?.sampleCount).toBe(3);
+    expect((rows[0]?.samples as unknown[]).length).toBe(3);
+  });
+
+  it("attaches both a route and an HR series on one workout", async () => {
+    vi.mocked(prisma.workout.createMany).mockResolvedValue({ count: 1 });
+    vi.mocked(prisma.workout.findMany).mockImplementation((async (args: {
+      select?: { id?: true };
+    }) => {
+      if (args.select?.id) {
+        return [
+          {
+            id: "wkt-both-id",
+            source: "APPLE_HEALTH",
+            externalId: "uuid-both",
+          },
+        ];
+      }
+      return [];
+    }) as never);
+
+    const res = await POST(
+      makeRequest({
+        workouts: [
+          validWorkout("uuid-both", {
+            route: {
+              geometry: {
+                type: "LineString",
+                coordinates: [
+                  [11.077, 49.452],
+                  [11.078, 49.453],
+                ],
+              },
+            },
+            samples: [{ t: "2026-05-14T06:30:00.000Z", hr: 142 }],
+          }),
+        ],
+      }),
+    );
+    expect(res.status).toBe(200);
+    expect(prisma.workoutRoute.createMany).toHaveBeenCalledTimes(1);
+    expect(prisma.workoutSamples.createMany).toHaveBeenCalledTimes(1);
+    const routeRows = (
+      vi.mocked(prisma.workoutRoute.createMany).mock.calls[0]?.[0] as {
+        data: Array<{ workoutId: string }>;
+      }
+    ).data;
+    const sampleRows = (
+      vi.mocked(prisma.workoutSamples.createMany).mock.calls[0]?.[0] as {
+        data: Array<{ workoutId: string }>;
+      }
+    ).data;
+    // Both children attach to the SAME freshly-inserted workout id.
+    expect(routeRows[0]?.workoutId).toBe("wkt-both-id");
+    expect(sampleRows[0]?.workoutId).toBe("wkt-both-id");
+  });
+
+  it("does not touch the samples table when no workout ships a series", async () => {
+    vi.mocked(prisma.workout.createMany).mockResolvedValue({ count: 1 });
+    const res = await POST(
+      makeRequest({ workouts: [validWorkout("uuid-no-series")] }),
+    );
+    expect(res.status).toBe(200);
+    expect(prisma.workoutSamples.createMany).not.toHaveBeenCalled();
+  });
+});
+
 describe("POST /api/workouts/batch — user source-priority (v1.4.43 W9)", () => {
   it("looks up the user's source-priority blob exactly once per batch", async () => {
     vi.mocked(prisma.workout.createMany).mockResolvedValue({ count: 1 });

src/app/api/workouts/batch/route.ts

@@ -218,6 +218,13 @@ async function postBatch(request: NextRequest): Promise<Response> {
       geometry: unknown;
       sampleTimestamps: unknown;
     } | null;
+    /** Route-independent per-workout HR series. NULL when the entry
+     *  ships no `samples` array. Persisted to the `WorkoutSamples`
+     *  child by FK after the workout row lands. */
+    samples: {
+      samples: unknown;
+      sampleCount: number;
+    } | null;
     /** Composite-key probe for the pre-flight findMany. NULL when
      *  the entry has no externalId — those rows always pass through
      *  as "inserted" because the NULL-distinct unique index can never
@@ -237,6 +244,12 @@ async function postBatch(request: NextRequest): Promise<Response> {
           sampleTimestamps: (w.route.sampleTimestamps ?? null) as unknown,
         }
       : null;
+    const samples = w.samples
+      ? {
+          samples: w.samples as unknown,
+          sampleCount: w.samples.length,
+        }
+      : null;
     const row: Prisma.WorkoutCreateManyInput = {
       userId: user.id,
       sportType: w.sportType,
@@ -262,6 +275,7 @@ async function postBatch(request: NextRequest): Promise<Response> {
       index,
       row,
       route,
+      samples,
       dedupKey: w.externalId
         ? { source: w.source, externalId: w.externalId }
         : null,
@@ -372,19 +386,27 @@ async function postBatch(request: NextRequest): Promise<Response> {
         }
 
         // Look up the workouts we just wrote (or that the racing batch
-        // wrote) so we can attach routes by FK. We probe by the
+        // wrote) so we can attach their child rows (route geometry +
+        // the route-independent HR series) by FK. We probe by the
         // composite unique key for entries that have one, and by the
         // `(userId, source, startedAt, sportType)` tuple as a fallback
         // for manual entries (where externalId is null). The fallback
         // is best-effort — manual entries from the iOS client always
         // carry an HK uuid, so the null-externalId case is exercised
         // only by future surface (manual workout entry).
-        const routeAttachable = toInsert.filter((p) => p.route !== null);
-        if (routeAttachable.length > 0) {
-          const withExternal = routeAttachable.filter(
+        //
+        // v1.10.0 — `samples` (the per-workout HR series) rides the
+        // SAME id lookup as `route`: an indoor workout carries samples
+        // with no route, so the lookup runs whenever EITHER child is
+        // present on a to-insert entry.
+        const childAttachable = toInsert.filter(
+          (p) => p.route !== null || p.samples !== null,
+        );
+        if (childAttachable.length > 0) {
+          const withExternal = childAttachable.filter(
             (p) => p.dedupKey !== null,
           );
-          const withoutExternal = routeAttachable.filter(
+          const withoutExternal = childAttachable.filter(
             (p) => p.dedupKey === null,
           );
 
@@ -463,13 +485,30 @@ async function postBatch(request: NextRequest): Promise<Response> {
             return match ? { id: match.id } : null;
           });
 
+          // Resolve the freshly-written workout id for a prepared
+          // entry — by composite key for externalId-bearing rows, by
+          // the deterministic (source, startedAt, sportType) tuple for
+          // manual rows. Shared by both child tables (route + samples)
+          // so the HR series and the route attach to the same row.
+          const resolveId = (
+            p: Prepared,
+            manualIndex: number,
+          ): string | undefined => {
+            if (p.dedupKey !== null) {
+              return idBySourceExt.get(
+                `${p.dedupKey.source}::${p.dedupKey.externalId}`,
+              );
+            }
+            return manualMatches[manualIndex]?.id ?? undefined;
+          };
+
           const routesToInsert: Prisma.WorkoutRouteCreateManyInput[] = [];
+          const samplesToInsert: Prisma.WorkoutSamplesCreateManyInput[] = [];
           for (let i = 0; i < withExternal.length; i++) {
             const p = withExternal[i];
-            const id = idBySourceExt.get(
-              `${p.dedupKey!.source}::${p.dedupKey!.externalId}`,
-            );
-            if (id && p.route) {
+            const id = resolveId(p, -1);
+            if (!id) continue;
+            if (p.route) {
               routesToInsert.push({
                 workoutId: id,
                 geometry: p.route.geometry as Prisma.InputJsonValue,
@@ -479,13 +518,21 @@ async function postBatch(request: NextRequest): Promise<Response> {
                     : (p.route.sampleTimestamps as Prisma.InputJsonValue),
               });
             }
+            if (p.samples) {
+              samplesToInsert.push({
+                workoutId: id,
+                samples: p.samples.samples as Prisma.InputJsonValue,
+                sampleCount: p.samples.sampleCount,
+              });
+            }
           }
           for (let i = 0; i < withoutExternal.length; i++) {
             const p = withoutExternal[i];
-            const match = manualMatches[i];
-            if (match?.id && p.route) {
+            const id = resolveId(p, i);
+            if (!id) continue;
+            if (p.route) {
               routesToInsert.push({
-                workoutId: match.id,
+                workoutId: id,
                 geometry: p.route.geometry as Prisma.InputJsonValue,
                 sampleTimestamps:
                   p.route.sampleTimestamps === null
@@ -493,6 +540,13 @@ async function postBatch(request: NextRequest): Promise<Response> {
                     : (p.route.sampleTimestamps as Prisma.InputJsonValue),
               });
             }
+            if (p.samples) {
+              samplesToInsert.push({
+                workoutId: id,
+                samples: p.samples.samples as Prisma.InputJsonValue,
+                sampleCount: p.samples.sampleCount,
+              });
+            }
           }
 
           if (routesToInsert.length > 0) {
@@ -508,6 +562,19 @@ async function postBatch(request: NextRequest): Promise<Response> {
               });
             }
           }
+
+          if (samplesToInsert.length > 0) {
+            for (let i = 0; i < samplesToInsert.length; i += CHUNK) {
+              await tx.workoutSamples.createMany({
+                data: samplesToInsert.slice(i, i + CHUNK),
+                // 1:1 FK on `workoutId` (UNIQUE), same idempotency as
+                // the route child: a re-submitted batch that wins the
+                // workout-row race but loses the sample-row race is a
+                // no-op, not a hard error.
+                skipDuplicates: true,
+              });
+            }
+          }
         }
       });