diff --git a/src/__tests__/workout-canonical-identity-guard.test.ts b/src/__tests__/workout-canonical-identity-guard.test.ts
index 73fb493fb..416faa7e5 100644
--- a/src/__tests__/workout-canonical-identity-guard.test.ts
+++ b/src/__tests__/workout-canonical-identity-guard.test.ts
@@ -31,7 +31,7 @@ const SRC = join(process.cwd(), "src");
 const PICKER = "lib/measurements/pick-canonical-workout-rows.ts";
 
 /**
- * Every production call site of the read-time picker, frozen.
+ * Every production call site of the picker, frozen.
  *
  * Adding a surface that collapses workouts is a deliberate act: it must fetch
  * the identity fields or it silently disagrees with every other surface. Adding
@@ -48,6 +48,18 @@ const IDENTITY_OWNER: Record<string, string> = {
   // block's data. Recording the owner here rather than assuming the call site
   // owns its own select is the whole point of this map.
   "lib/ai/coach/snapshot-blocks/workouts-block.ts": "lib/ai/coach/snapshot.ts",
+  // The write path: the batch route runs the same picker over the rows it is
+  // about to insert, so a duplicate inside one batch is dropped by the rule
+  // the list later applies.
+  "app/api/workouts/batch/route.ts": "app/api/workouts/batch/route.ts",
+};
+
+/**
+ * How a call site proves its rows carry the duration. A read selects the
+ * column; the batch route maps it off the row it computed for the insert.
+ */
+const IDENTITY_PROOF: Record<string, string> = {
+  "app/api/workouts/batch/route.ts": "durationSec: p.row.durationSec",
 };
 
 const EXPECTED_CALL_SITES = Object.keys(IDENTITY_OWNER).sort();
@@ -65,10 +77,8 @@ function read(rel: string): string {
 }
 
 /**
- * Lines that actually invoke the picker. Comment lines are excluded because the
- * write-time sibling (`lib/workouts/canonical-rows.ts`) names the read-time
- * picker in its docblock to explain how the two layer, and that mention is
- * documentation rather than a call.
+ * Lines that actually invoke the picker. Comment lines are excluded: a
+ * docblock that names the picker is documentation rather than a call.
  */
 function invokesPicker(source: string): boolean {
   return source
@@ -104,7 +114,9 @@ describe("every call site fetches the session identity", () => {
     // rows came from. Coarse in the safe direction — it can only fail to catch
     // a second unrelated select in the same file, never pass a caller that
     // fetches no duration at all.
-    expect(read(IDENTITY_OWNER[rel])).toContain("durationSec: true");
+    expect(read(IDENTITY_OWNER[rel])).toContain(
+      IDENTITY_PROOF[rel] ?? "durationSec: true",
+    );
   });
 });
 
diff --git a/src/app/api/workouts/batch/route.ts b/src/app/api/workouts/batch/route.ts
index 6d3e30d85..db2d1b1c7 100644
--- a/src/app/api/workouts/batch/route.ts
+++ b/src/app/api/workouts/batch/route.ts
@@ -91,7 +91,7 @@ import {
   UNSTABLE_EXTERNAL_ID_REASON,
   type UnstableExternalIdShape,
 } from "@/lib/validations/external-id";
-import { dedupeWorkoutBatch } from "@/lib/workouts/canonical-rows";
+import { pickCanonicalWorkoutRows } from "@/lib/measurements/pick-canonical-workout-rows";
 import { WORKOUTS_WRITE_SCOPE } from "@/lib/workouts/scopes";
 import { EXTERNAL_SOURCE } from "@/lib/measurements/external-source";
 import { encryptRouteGeometry } from "@/lib/workouts/route-geometry-cipher";
@@ -494,41 +494,29 @@ async function postBatch(request: NextRequest): Promise<Response> {
     });
   }
 
-  // v1.4.42 W5 — write-time cross-source dedup. The v1.5 iOS app
-  // drains a HealthKit observer queue that frequently carries the
-  // SAME logical workout from two paired sensors (Apple Watch +
-  // Withings ScanWatch). Without this pass, both rows persist (their
-  // `externalId`s differ → the `(userId, source, externalId)` unique
-  // index never fires) and the read-time canonical-picker has to
-  // carry the duplicate forward on every dashboard render.
-  //
-  // The helper is pure (no Prisma, no user lookups). It groups by
-  // `(userId, activityType, startedAt ± 90 s)`, prefers the canonical
-  // source ladder (APPLE_HEALTH > WITHINGS > MANUAL > IMPORT), and
-  // breaks ties on calories > earliest createdAt > input order. Rows
-  // dropped here surface to the iOS client as `duplicate` so the
-  // sync cursor advances past them identically to the externalId
-  // case below.
-  const canonicalPrepared = dedupeWorkoutBatch(
+  // Write-time cross-source dedup through the one workout picker the reads
+  // use, with the same source ladder: one logical workout from two sources
+  // in one batch (or one HealthKit session re-sent under a new id) lands
+  // once. Rows the picker hides surface to the client as `duplicate`, so
+  // the sync cursor advances past them like the externalId case below.
+  const canonicalPrepared = pickCanonicalWorkoutRows(
     prepared.map((p) => ({
+      index: p.index,
       userId: p.row.userId,
-      activityType: p.row.sportType,
+      sportType: p.row.sportType,
       startedAt: p.row.startedAt as Date,
+      durationSec: p.row.durationSec,
       // Zod's `measurementSourceEnum.optional().default("MANUAL")`
       // guarantees `source` is set post-parse, but Prisma's
-      // `WorkoutCreateManyInput` types it optional. Default through
-      // the same fallback the validator uses so the picker's source
-      // ladder still resolves on the rare row where TypeScript
-      // can't prove the union.
+      // `WorkoutCreateManyInput` types it optional.
       source: (p.row.source ?? "MANUAL") as MeasurementSource,
-      caloriesKcal: p.row.totalEnergyKcal ?? null,
-      // No createdAt yet — the row is pre-insert; the tie-breaker
-      // falls through to input order via the `index` field below.
-      index: p.index,
+      avgHeartRate: p.row.avgHeartRate ?? null,
+      maxHeartRate: p.row.maxHeartRate ?? null,
+      metadata: p.row.metadata ?? null,
     })),
     userPriority?.sourcePriorityJson ?? null,
   );
-  const survivingIndices = new Set(canonicalPrepared.map((r) => r.index ?? -1));
+  const survivingIndices = new Set(canonicalPrepared.map((r) => r.index));
   const droppedByWriteDedup: number[] = [];
   for (const p of prepared) {
     if (!survivingIndices.has(p.index)) {
diff --git a/src/lib/measurements/pick-canonical-workout-rows.ts b/src/lib/measurements/pick-canonical-workout-rows.ts
index cb97fd0ad..50fda8fdf 100644
--- a/src/lib/measurements/pick-canonical-workout-rows.ts
+++ b/src/lib/measurements/pick-canonical-workout-rows.ts
@@ -14,11 +14,9 @@
  *      logical run start within a minute of each other on both
  *      sources; the rounding gives the cross-source matcher slack
  *      without collapsing distinct back-to-back workouts.
- *   2. For each bucket, walk the SOURCE priority ladder
- *      (`APPLE_HEALTH ≻ WITHINGS ≻ MANUAL ≻ IMPORT` per the existing
- *      source-priority validator's default) and pick the FIRST
- *      source that has any row in that bucket. Keep every row from
- *      the winning source; drop the rest.
+ *   2. For each bucket, walk the source ladder (`workoutSourceLadder`)
+ *      and pick the FIRST source that has any row in that bucket. Keep
+ *      every row from the winning source; drop the rest.
  *   3. Rows whose source isn't in the ladder pass through untouched
  *      (fallback intent — never silently drop signal).
  *
@@ -26,10 +24,10 @@
  * (typically `ORDER BY startedAt ASC, id ASC` from the caller's
  * Prisma read). The output preserves input order.
  *
- * Future v1.5.x tune: metric-aware picker per R-F open question #4 —
- * route → Apple wins, HR zones → Withings wins. Out of scope for
- * v1.4.30; the existing ladder ships first so the dashboard tile is
- * unambiguous.
+ * This is the one workout picker. The reads use it, and so does the batch
+ * write route before it inserts: a write-time picker with its own window
+ * and a different default ladder kept or dropped a different row than the
+ * list then showed.
  */
 import type { MeasurementSource } from "@/generated/prisma/client";
 
@@ -249,6 +247,17 @@ function enrichWinnersFromWhoop<T extends WorkoutPickerRow>(
   return enriched;
 }
 
+/**
+ * The source order for workouts: the `steps` metric's ladder, the
+ * canonical-activity bucket the Sources settings configure, falling back to
+ * its default when the user saved none or it does not parse.
+ */
+export function workoutSourceLadder(
+  userPriorityJson: unknown,
+): readonly MeasurementSource[] {
+  return getSourceLadder(parseSourcePriority(userPriorityJson), "steps");
+}
+
 /**
  * Pick canonical rows across sources for a user's workouts.
  *
@@ -266,14 +275,7 @@ export function pickCanonicalWorkoutRows<T extends WorkoutPickerRow>(
 ): T[] {
   if (rows.length === 0) return [];
 
-  // Workouts ride the `steps` metric's source ladder — the
-  // canonical-activity bucket. The user's iOS Settings → Sources UI
-  // configures the same ladder for the workout dashboard tile;
-  // unifying on "steps" keeps a single configuration surface rather
-  // than introducing a new `workouts` metric key. Future ladders for
-  // workout-specific tunes (route-vs-zones) ride a v1.5.x change.
-  const resolved = parseSourcePriority(userPriorityJson);
-  const sourceLadder = getSourceLadder(resolved, "steps");
+  const sourceLadder = workoutSourceLadder(userPriorityJson);
 
   const buckets = new Map<
     string,
diff --git a/src/lib/polar/__tests__/dedup.test.ts b/src/lib/polar/__tests__/dedup.test.ts
index 0352b40be..21b379f01 100644
--- a/src/lib/polar/__tests__/dedup.test.ts
+++ b/src/lib/polar/__tests__/dedup.test.ts
@@ -1,7 +1,9 @@
 import { describe, expect, it } from "vitest";
 
-import { pickCanonicalWorkoutRows } from "@/lib/measurements/pick-canonical-workout-rows";
-import { DEFAULT_WORKOUT_SOURCE_PRIORITY } from "@/lib/sources/pick-canonical-workout";
+import {
+  pickCanonicalWorkoutRows,
+  workoutSourceLadder,
+} from "@/lib/measurements/pick-canonical-workout-rows";
 import { DEFAULT_SOURCE_PRIORITY } from "@/lib/validations/source-priority";
 
 /**
@@ -68,10 +70,10 @@ describe("POLAR workout dedup — read-time canonical picker", () => {
 });
 
 describe("POLAR sits in the workout source ladders", () => {
-  it("is present in the workout default ladder, below WITHINGS, above STRAVA", () => {
-    const polar = DEFAULT_WORKOUT_SOURCE_PRIORITY.indexOf("POLAR");
-    const withings = DEFAULT_WORKOUT_SOURCE_PRIORITY.indexOf("WITHINGS");
-    const strava = DEFAULT_WORKOUT_SOURCE_PRIORITY.indexOf("STRAVA");
+  it("is present in the workout ladder, below WITHINGS, above STRAVA", () => {
+    const polar = workoutSourceLadder(null).indexOf("POLAR");
+    const withings = workoutSourceLadder(null).indexOf("WITHINGS");
+    const strava = workoutSourceLadder(null).indexOf("STRAVA");
     expect(polar).toBeGreaterThan(withings);
     expect(polar).toBeLessThan(strava);
   });
diff --git a/src/lib/strava/__tests__/dedup.test.ts b/src/lib/strava/__tests__/dedup.test.ts
index 889c2e2a2..e74f9075f 100644
--- a/src/lib/strava/__tests__/dedup.test.ts
+++ b/src/lib/strava/__tests__/dedup.test.ts
@@ -1,7 +1,9 @@
 import { describe, expect, it } from "vitest";
 
-import { pickCanonicalWorkoutRows } from "@/lib/measurements/pick-canonical-workout-rows";
-import { DEFAULT_WORKOUT_SOURCE_PRIORITY } from "@/lib/sources/pick-canonical-workout";
+import {
+  pickCanonicalWorkoutRows,
+  workoutSourceLadder,
+} from "@/lib/measurements/pick-canonical-workout-rows";
 import { DEFAULT_SOURCE_PRIORITY } from "@/lib/validations/source-priority";
 
 /**
@@ -67,10 +69,10 @@ describe("STRAVA workout dedup — read-time canonical picker", () => {
 });
 
 describe("STRAVA sits in the workout source ladders", () => {
-  it("is present in the workout default ladder, below the wearables, above MANUAL", () => {
-    const strava = DEFAULT_WORKOUT_SOURCE_PRIORITY.indexOf("STRAVA");
-    const withings = DEFAULT_WORKOUT_SOURCE_PRIORITY.indexOf("WITHINGS");
-    const manual = DEFAULT_WORKOUT_SOURCE_PRIORITY.indexOf("MANUAL");
+  it("is present in the workout ladder, below the wearables, above MANUAL", () => {
+    const strava = workoutSourceLadder(null).indexOf("STRAVA");
+    const withings = workoutSourceLadder(null).indexOf("WITHINGS");
+    const manual = workoutSourceLadder(null).indexOf("MANUAL");
     expect(strava).toBeGreaterThan(withings);
     expect(strava).toBeLessThan(manual);
   });
diff --git a/src/lib/strava/sport-map.ts b/src/lib/strava/sport-map.ts
index c3702e9f8..b60c7a675 100644
--- a/src/lib/strava/sport-map.ts
+++ b/src/lib/strava/sport-map.ts
@@ -7,11 +7,10 @@
  * to write `summary.sport_type ?? summary.type ?? detail?.sport_type ??
  * "workout"` straight into `Workout.sportType`, so a Strava "Run" or
  * "VirtualRide" never matched a canonical bucket — `/insights/workouts`
- * rendered every Strava row generic, and the read-time picker in
- * `src/lib/sources/pick-canonical-workout.ts` treats any two GENERIC rows
- * as sport-compatible, so a same-source brick session (a Strava "Ride"
- * ending 15:00 immediately followed by a Strava "Run" starting 15:03)
- * clustered into one and silently dropped a leg. Fitbit
+ * rendered every Strava row generic, and a picker that treats two generic
+ * rows as the same sport clusters a same-source brick session (a Strava
+ * "Ride" ending 15:00 immediately followed by a Strava "Run" starting
+ * 15:03) into one and silently drops a leg. Fitbit
  * (`mapFitbitSportType()` in `src/lib/fitbit/client.ts`), Google Health
  * (`mapGoogleHealthSportType()` in `src/lib/google-health/mappers.ts`), and
  * WHOOP (`mapWhoopSportType()` in `src/lib/whoop/sport-map.ts`) all
diff --git a/tests/integration/workout-batch-create.test.ts b/tests/integration/workout-batch-create.test.ts
index b7f7f3274..190fa34ef 100644
--- a/tests/integration/workout-batch-create.test.ts
+++ b/tests/integration/workout-batch-create.test.ts
@@ -356,8 +356,16 @@ describe("POST /api/workouts/batch (real Postgres)", () => {
   it("preserves same-source workouts and surfaces exact re-posts as duplicates", async () => {
     const { POST } = await import("@/app/api/workouts/batch/route");
 
+    // Two sessions of one source in the same five-minute slot: different
+    // start and length, so two workouts.
     const body = {
-      workouts: [baseWorkout("hk-uuid-dup-1"), baseWorkout("hk-uuid-dup-2")],
+      workouts: [
+        baseWorkout("hk-uuid-dup-1"),
+        baseWorkout("hk-uuid-dup-2", {
+          startedAt: "2026-05-14T06:32:00.000Z",
+          endedAt: "2026-05-14T06:50:00.000Z",
+        }),
+      ],
     };
 
     const first = await POST(makeRequest(body));
@@ -393,6 +401,31 @@ describe("POST /api/workouts/batch (real Postgres)", () => {
     expect(stored).toBe(2);
   });
 
+  it("stores a session re-sent under a new id once, the way the list shows it", async () => {
+    // HealthKit can hand the same session over twice with two external ids.
+    // The list collapses it to one workout; the write keeps one row and
+    // reports the other as a duplicate instead of storing what no read shows.
+    const { POST } = await import("@/app/api/workouts/batch/route");
+    const res = await POST(
+      makeRequest({
+        workouts: [
+          baseWorkout("hk-uuid-resend-1"),
+          baseWorkout("hk-uuid-resend-2"),
+        ],
+      }),
+    );
+    expect(res.status).toBe(200);
+    const json = (await res.json()) as {
+      data: { inserted: number; duplicates: number };
+    };
+    expect(json.data.inserted).toBe(1);
+    expect(json.data.duplicates).toBe(1);
+    const stored = await getPrismaClient().workout.count({
+      where: { userId: TEST_USER_ID },
+    });
+    expect(stored).toBe(1);
+  });
+
   it("replays a cached response when the same Idempotency-Key is reused", async () => {
     const { POST } = await import("@/app/api/workouts/batch/route");
 
diff --git a/tests/integration/workout-batch-race.test.ts b/tests/integration/workout-batch-race.test.ts
index bc5a9361c..d55aed62b 100644
--- a/tests/integration/workout-batch-race.test.ts
+++ b/tests/integration/workout-batch-race.test.ts
@@ -182,9 +182,9 @@ describe("POST /api/workouts/batch — concurrent-write race", () => {
     const { POST } = await import("@/app/api/workouts/batch/route");
 
     // Batch A — a cross-source pair one minute apart plus one shared key.
-    // The v1.4.42 `dedupeWorkoutBatch` picker collapses the Apple Health +
-    // Manual pair (same activity, within the 90 s window) to one
-    // surviving row, leaving 2 effective rows per batch.
+    // The workout picker collapses the Apple Health + Manual pair (same
+    // activity, same five-minute slot) to one surviving row, leaving 2
+    // effective rows per batch.
     const batchA: WorkoutFixture[] = [
       workout("hk-uuid-only-a-0", 1),
       workout("hk-uuid-only-a-1", 2, "MANUAL"),