diff --git a/src/services/statcastAggregateService.js b/src/services/statcastAggregateService.js
index 2826804..391a33b 100644
--- a/src/services/statcastAggregateService.js
+++ b/src/services/statcastAggregateService.js
@@ -206,7 +206,12 @@ async function refreshSeason(opts = {}) {
     const batch = rows.slice(i, i + chunk).map(toDbRow);
     const { error } = await sb
       .from('statcast_aggregates')
-      .upsert(batch, { onConflict: 'sport,season,source_id' });
+      // ROLE is part of the key: a two-way player has a real batter profile AND
+      // a real pitcher profile, and merging them would invent one player out of
+      // two genuinely different sets of measurements. (Found by inducing the
+      // job: without role, one batch hit the same row twice and Postgres
+      // refused the chunk.)
+      .upsert(batch, { onConflict: 'sport,season,source_id,role' });
     if (error) {
       summary.ok = false;
       summary.reason = `upsert failed: ${error.message}`;
diff --git a/supabase/migrations/030_statcast_aggregates.sql b/supabase/migrations/030_statcast_aggregates.sql
index a70421a..8cc431a 100644
--- a/supabase/migrations/030_statcast_aggregates.sql
+++ b/supabase/migrations/030_statcast_aggregates.sql
@@ -60,7 +60,9 @@ create table if not exists statcast_aggregates (
   updated_at    timestamptz not null default now(),
   source        text        not null default 'baseball_savant',
 
-  primary key (sport, season, source_id)
+  -- ROLE is in the key: two-way players have a real batter profile AND a
+  -- real pitcher profile (see migration 031).
+  primary key (sport, season, source_id, role)
 );
 
 create index if not exists statcast_agg_player_key_idx on statcast_aggregates (sport, season, player_key);
diff --git a/tests/unit/statcastAggregate.test.js b/tests/unit/statcastAggregate.test.js
index e88eb58..6cdd628 100644
--- a/tests/unit/statcastAggregate.test.js
+++ b/tests/unit/statcastAggregate.test.js
@@ -131,7 +131,7 @@ describe('refreshSeason — the job', () => {
     let opts = null;
     const sb = { from: () => ({ upsert: async (_b, o) => { opts = o; return { error: null }; } }) };
     await svc.refreshSeason({ supabase: sb, fetchSeason: async () => feeds({ batter: [BELL] }) });
-    expect(opts.onConflict).toBe('sport,season,source_id');
+    expect(opts.onConflict).toBe('sport,season,source_id,role');
   });
 
   it('REFUSES to write when every feed is empty — a bad night cannot blank a good table', async () => {
@@ -148,6 +148,18 @@ describe('refreshSeason — the job', () => {
     expect(sb.calls[0][0]._sufficient).toBeUndefined();
   });
 
+  it('keys two-way players by ROLE — one player, two real profiles', async () => {
+    // Ohtani appears in both the batter and the pitcher feeds. Without role in
+    // the key, one upsert batch hits the same row twice and Postgres refuses
+    // the whole chunk — found by inducing the real job, not by review.
+    const OHTANI_B = { 'last_name, first_name': 'Ohtani, Shohei', player_id: '660271', pa: '400' };
+    const OHTANI_P = { 'last_name, first_name': 'Ohtani, Shohei', player_id: '660271', p_formatted_ip: '40' };
+    const rows = svc.buildRows(2026, feeds({ batter: [OHTANI_B], pitcher: [OHTANI_P] }), {});
+    expect(rows).toHaveLength(2);
+    expect(new Set(rows.map((r) => r.source_id)).size).toBe(1);
+    expect(new Set(rows.map((r) => r.role))).toEqual(new Set(['batter', 'pitcher']));
+  });
+
   it('reports the join rate — the honest-absent rate for the mechanism tier', async () => {
     const out = await svc.refreshSeason({
       supabase: okClient(),