diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index 44be07550..912c6bbd7 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -162,6 +162,17 @@ jobs:
             -t "${COMPOSE_PROJECT_NAME}-${{ matrix.service }}-migration" \
             .
 
+      - name: Resolve failed migrations for ${{ matrix.service }}
+        if: matrix.service == 'passenger-api'
+        run: |
+          set -euo pipefail
+          docker run --rm --env-file "${SERVICE_ENV_FILE}" \
+            --entrypoint npx \
+            "${COMPOSE_PROJECT_NAME}-${{ matrix.service }}-migration" \
+            prisma migrate resolve \
+            --applied 20260718144855_unique_constraint_schedule_id_seat_id_departure_station_id \
+            || true
+
       - name: Run migrations for ${{ matrix.service }}
         if: contains(fromJson('["passenger-api", "payment-api"]'), matrix.service)
         run: |
diff --git a/apps/edr-passenger-api/prisma/migrations/20260718144855_unique_constraint_schedule_id_seat_id_departure_station_id/migration.sql b/apps/edr-passenger-api/prisma/migrations/20260718144855_unique_constraint_schedule_id_seat_id_departure_station_id/migration.sql
index 2b67ec9cf..a512eeccd 100644
--- a/apps/edr-passenger-api/prisma/migrations/20260718144855_unique_constraint_schedule_id_seat_id_departure_station_id/migration.sql
+++ b/apps/edr-passenger-api/prisma/migrations/20260718144855_unique_constraint_schedule_id_seat_id_departure_station_id/migration.sql
@@ -4,5 +4,17 @@
   - A unique constraint covering the columns `[scheduleId,seatId,departureStationId]` on the table `JourneySegment` will be added. If there are existing duplicate values, this will fail.
 
 */
+-- Deduplicate before applying the unique index.
+-- Keeps the row with the lowest id per (scheduleId, seatId, departureStationId) group.
+DELETE FROM passenger."JourneySegment"
+WHERE id NOT IN (
+  SELECT MIN(id)
+  FROM passenger."JourneySegment"
+  WHERE "seatId" IS NOT NULL
+  GROUP BY "scheduleId", "seatId", "departureStationId"
+)
+AND "seatId" IS NOT NULL;
+
 -- CreateIndex
-CREATE UNIQUE INDEX IF NOT EXISTS "JourneySegment_scheduleId_seatId_departureStationId_key" ON "JourneySegment"("scheduleId", "seatId", "departureStationId");
+CREATE UNIQUE INDEX IF NOT EXISTS "JourneySegment_scheduleId_seatId_departureStationId_key"
+  ON "JourneySegment"("scheduleId", "seatId", "departureStationId");