fix(workouts): read the stored route sample shape for splits and the GPX export

Both ingests store each route point's sample as { t, speedMs?, hr? }, while
computeSplits parsed every sample as a bare instant and the GPX export
skipped anything that was not a string. Splits were therefore null for
every ingested track, and an exported track carried no times. One reader,
routeSampleInstant, takes either shape. The workout detail walk is
re-pinned: its ingested run now answers its first kilometre split.

src/hooks/use-workouts.ts

@@ -7,6 +7,7 @@ import { useInfiniteQuery, useQuery } from "@tanstack/react-query";
 import { useAuth } from "@/hooks/use-auth";
 import { queryKeys } from "@/lib/query-keys";
 import { apiGet } from "@/lib/api/api-fetch";
+import type { RouteSample } from "@/lib/workouts/route-samples";
 
 /**
  * v1.4.32 — TanStack Query wrapper for `GET /api/workouts`.
@@ -325,7 +326,7 @@ export interface WorkoutDetailPayload extends WorkoutListEntry {
   metadata: unknown;
   route: {
     geometry: unknown;
-    sampleTimestamps: string[] | null;
+    sampleTimestamps: RouteSample[] | null;
   } | null;
   /**
    * Raw per-workout HR sample envelope. `samples.samples` is dropped

src/lib/workouts/__tests__/route-svg.test.ts

@@ -150,6 +150,23 @@ describe("haversineMeters", () => {
 });
 
 describe("buildGpxDocument", () => {
+  it("writes the instant of a stored sample object", () => {
+    const gpx = buildGpxDocument({
+      coordinates: [
+        [11.0, 50.0],
+        [11.001, 50.001],
+      ],
+      timestamps: [
+        { t: "2026-05-15T07:00:00Z", hr: 120 },
+        { t: "2026-05-15T07:00:05Z", speedMs: 3.1 },
+      ],
+      sportType: "running",
+      startedAt: "2026-05-15T07:00:00Z",
+    });
+    expect(gpx).toContain("<time>2026-05-15T07:00:00Z</time>");
+    expect(gpx).toContain("<time>2026-05-15T07:00:05Z</time>");
+  });
+
   it("emits trkpt elements with elevation and time when present", () => {
     const gpx = buildGpxDocument({
       coordinates: [

src/lib/workouts/__tests__/splits.test.ts

@@ -42,6 +42,16 @@ describe("computeSplits", () => {
     }
   });
 
+  it("reads the stored sample shape, an instant with its channels", () => {
+    // Both ingests store `{ t, speedMs?, hr? }` per point; older tracks a
+    // bare instant. The two shapes time the same track identically.
+    const { coords, timestamps } = track(3200, 320, 960);
+    const samples = timestamps.map((t, i) => ({ t, hr: 120 + (i % 30) }));
+    const splits = computeSplits(coords, samples);
+    expect(splits).not.toBeNull();
+    expect(splits).toEqual(computeSplits(coords, timestamps));
+  });
+
   it("returns null without aligned timestamps", () => {
     const { coords } = track(3000, 300, 900);
     expect(computeSplits(coords, null)).toBeNull();

src/lib/workouts/detail.ts

@@ -237,7 +237,7 @@ async function readEnrichment(
       : null;
   const splits =
     geometryCoords && Array.isArray(row.route?.sampleTimestamps)
-      ? computeSplits(geometryCoords, row.route.sampleTimestamps as string[])
+      ? computeSplits(geometryCoords, row.route.sampleTimestamps)
       : null;
 
   // Sport context: the user's own last-180-days average for this

src/lib/workouts/route-samples.ts

@@ -0,0 +1,17 @@
+/**
+ * One point of a stored route's `sampleTimestamps`, aligned with the
+ * geometry's coordinates. Both ingests store `{ t, speedMs?, hr? }`; tracks
+ * written before the per-point channels carry a bare ISO instant. Every
+ * reader goes through `routeSampleInstant` so neither shape is skipped.
+ */
+export type RouteSample = string | { t: string; speedMs?: number; hr?: number };
+
+/** The ISO instant of one sample, or null when it carries none. */
+export function routeSampleInstant(sample: unknown): string | null {
+  if (typeof sample === "string") return sample.length > 0 ? sample : null;
+  if (typeof sample === "object" && sample !== null && "t" in sample) {
+    const t = (sample as { t: unknown }).t;
+    return typeof t === "string" && t.length > 0 ? t : null;
+  }
+  return null;
+}

src/lib/workouts/route-svg.ts

@@ -16,6 +16,7 @@
  * correction squashes the longitude axis by `cos(midLat)` so one screen
  * unit east equals one screen unit north in real metres.
  */
+import { routeSampleInstant } from "@/lib/workouts/route-samples";
 
 export type RouteCoordinate =
   [number, number] | [number, number, number] | number[];
@@ -323,7 +324,8 @@ function escapeXml(value: string): string {
  */
 export function buildGpxDocument(params: {
   coordinates: readonly RouteCoordinate[];
-  timestamps?: readonly string[] | null;
+  /** The stored samples: an instant each, or `{ t, … }` (`RouteSample`). */
+  timestamps?: readonly unknown[] | null;
   sportType: string;
   startedAt: string;
 }): string {
@@ -336,8 +338,8 @@ export function buildGpxDocument(params: {
     if (!isFiniteNumber(lon) || !isFiniteNumber(lat)) return;
     const parts = [`<trkpt lat="${lat}" lon="${lon}">`];
     if (c.length >= 3 && isFiniteNumber(c[2])) parts.push(`<ele>${c[2]}</ele>`);
-    const ts = timestamps?.[i];
-    if (typeof ts === "string" && ts.length > 0) {
+    const ts = routeSampleInstant(timestamps?.[i]);
+    if (ts) {
       parts.push(`<time>${escapeXml(ts)}</time>`);
     }
     parts.push(`</trkpt>`);

src/lib/workouts/splits.ts

@@ -14,6 +14,7 @@ import {
   haversineMeters,
   type RouteCoordinate,
 } from "@/lib/workouts/route-svg";
+import { routeSampleInstant } from "@/lib/workouts/route-samples";
 
 export interface WorkoutSplit {
   /** 1-based kilometre index. */
@@ -34,7 +35,8 @@ const KM = 1000;
  */
 export function computeSplits(
   coordinates: readonly RouteCoordinate[],
-  timestamps: readonly string[] | null | undefined,
+  /** The stored samples: an instant each, or `{ t, … }` (`RouteSample`). */
+  timestamps: readonly unknown[] | null | undefined,
 ): WorkoutSplit[] | null {
   if (!timestamps || timestamps.length !== coordinates.length) return null;
 
@@ -43,7 +45,7 @@ export function computeSplits(
   coordinates.forEach((c, i) => {
     const [lonLat] = extractLonLat([c]);
     if (!lonLat) return;
-    const tMs = Date.parse(timestamps[i] ?? "");
+    const tMs = Date.parse(routeSampleInstant(timestamps[i]) ?? "");
     if (!Number.isFinite(tMs)) return;
     pts.push({ lon: lonLat[0], lat: lonLat[1], tMs });
   });

tests/integration/routes/parity/__snapshots__/workout-detail.get-01-canonical.json.snap

@@ -145,7 +145,13 @@
           }
         ]
       },
-      "splits": null,
+      "splits": [
+        {
+          "km": 1,
+          "durationSec": 530,
+          "paceSecPerKm": 530
+        }
+      ],
       "sportContext": {
         "count": 1,
         "avgDurationSec": 1800,

tests/integration/routes/parity/__snapshots__/workout-detail.get-02-compact.json.snap

@@ -115,7 +115,13 @@
           }
         ]
       },
-      "splits": null,
+      "splits": [
+        {
+          "km": 1,
+          "durationSec": 530,
+          "paceSecPerKm": 530
+        }
+      ],
       "sportContext": {
         "count": 1,
         "avgDurationSec": 1800,