Prevent duplicate participants within a sports season, fixes #69 (#236)

- Add unique index on (sports_season_id, name) in participants table
- findParticipantByName uses case-insensitive lower() comparison
- Single add: check for existing name before insert, return clear error
- Bulk add: load existing names once upfront (1 query vs N), dedup
  input case-insensitively, report skipped names in UI
- Fix golf-skills and surface-elo routes which called createParticipant
  without any duplicate guard (would have thrown DB constraint errors)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

app/models/participant.ts

@@ -1,4 +1,4 @@
-import { eq, inArray, count } from "drizzle-orm";
+import { eq, inArray, count, and, sql } from "drizzle-orm";
 import { database } from "~/database/context";
 import * as schema from "~/database/schema";
 
@@ -36,6 +36,24 @@ export async function findParticipantById(id: string): Promise<Participant | und
   });
 }
 
+export async function findParticipantByName(
+  sportsSeasonId: string,
+  name: string
+): Promise<Participant | undefined> {
+  const db = database();
+  const results = await db
+    .select()
+    .from(schema.participants)
+    .where(
+      and(
+        eq(schema.participants.sportsSeasonId, sportsSeasonId),
+        sql`lower(${schema.participants.name}) = lower(${name})`
+      )
+    )
+    .limit(1);
+  return results[0];
+}
+
 export async function findParticipantsBySportsSeasonId(sportsSeasonId: string): Promise<Participant[]> {
   const db = database();
   return await db.query.participants.findMany({

app/routes/admin.sports-seasons.$id.golf-skills.tsx

@@ -3,7 +3,7 @@ import type { Route } from './+types/admin.sports-seasons.$id.golf-skills';
 
 import { logger } from '~/lib/logger';
 import { findSportsSeasonById, updateSportsSeason } from '~/models/sports-season';
-import { findParticipantsBySportsSeasonId, createParticipant } from '~/models/participant';
+import { findParticipantsBySportsSeasonId, findParticipantByName, createParticipant } from '~/models/participant';
 import { batchUpsertParticipantEVs } from '~/models/participant-expected-value';
 import { batchUpsertParticipantEvSnapshots } from '~/models/ev-snapshot';
 import { getGolfSkillsForSeason, batchUpsertGolfSkills } from '~/models/golf-skills';
@@ -89,6 +89,10 @@ export async function action({ request, params }: Route.ActionArgs) {
     if (!name) {
       return { intent: 'create-participant', success: false, message: 'Name is required' } satisfies ActionData;
     }
+    const existing = await findParticipantByName(sportsSeasonId, name);
+    if (existing) {
+      return { intent: 'create-participant', success: false, message: `"${name}" already exists in this season.` } satisfies ActionData;
+    }
     const participant = await createParticipant({ sportsSeasonId, name });
     return {
       intent: 'create-participant',

app/routes/admin.sports-seasons.$id.participants.tsx

@@ -5,8 +5,9 @@ import { logger } from "~/lib/logger";
 import { findSportsSeasonById } from "~/models/sports-season";
 import {
   findParticipantsBySportsSeasonId,
+  findParticipantByName,
   createParticipant,
-  deleteParticipant 
+  deleteParticipant,
 } from "~/models/participant";
 import { Button } from "~/components/ui/button";
 import { Input } from "~/components/ui/input";
@@ -69,17 +70,30 @@ export async function action({ request, params }: Route.ActionArgs) {
       return { error: "Please enter at least one participant name" };
     }
 
-    const names = bulkNames
-      .split("\n")
-      .map(name => name.trim())
-      .filter(name => name.length > 0);
+    // Dedup case-insensitively, preserving first occurrence's casing
+    const seenKeys = new Map<string, string>();
+    for (const raw of bulkNames.split("\n").map(n => n.trim()).filter(n => n.length > 0)) {
+      const key = raw.toLowerCase();
+      if (!seenKeys.has(key)) seenKeys.set(key, raw);
+    }
+    const names = [...seenKeys.values()];
 
     if (names.length === 0) {
       return { error: "Please enter at least one participant name" };
     }
 
     try {
+      const existingParticipants = await findParticipantsBySportsSeasonId(params.id);
+      const existingNames = new Set(existingParticipants.map(p => p.name.toLowerCase()));
+
+      const skipped: string[] = [];
+      let added = 0;
+
       for (const name of names) {
+        if (existingNames.has(name.toLowerCase())) {
+          skipped.push(name);
+          continue;
+        }
         await createParticipant({
           sportsSeasonId: params.id,
           name,
@@ -87,9 +101,10 @@ export async function action({ request, params }: Route.ActionArgs) {
           externalId: null,
           expectedValue: "0",
         });
+        added++;
       }
 
-      return { success: true, count: names.length };
+      return { success: true, count: added, skipped };
     } catch (error) {
       logger.error("Error creating participants:", error);
       return { error: "Failed to add participants. Please try again." };
@@ -103,10 +118,16 @@ export async function action({ request, params }: Route.ActionArgs) {
     return { error: "Participant name is required" };
   }
 
+  const trimmedName = name.trim();
+  const existing = await findParticipantByName(params.id, trimmedName);
+  if (existing) {
+    return { error: `"${trimmedName}" already exists in this season.` };
+  }
+
   try {
     await createParticipant({
       sportsSeasonId: params.id,
-      name: name.trim(),
+      name: trimmedName,
       shortName: null,
       externalId: null,
       expectedValue: "0",
@@ -214,9 +235,14 @@ export default function ManageParticipants({ loaderData, actionData }: Route.Com
                   </div>
                 )}
 
-                {actionData?.success && actionData?.count && (
+                {actionData?.success && actionData?.count !== undefined && (
                   <div className="bg-emerald-500/15 text-emerald-400 px-4 py-3 rounded-md text-sm">
-                    {actionData.count} participant{actionData.count !== 1 ? 's' : ''} added successfully!
+                    {actionData.count} participant{actionData.count !== 1 ? 's' : ''} added.
+                    {actionData.skipped && actionData.skipped.length > 0 && (
+                      <span className="block mt-1 text-yellow-400">
+                        {actionData.skipped.length} skipped (already exist): {actionData.skipped.join(", ")}
+                      </span>
+                    )}
                   </div>
                 )}
 

app/routes/admin.sports-seasons.$id.surface-elo.tsx

@@ -3,7 +3,7 @@ import type { Route } from './+types/admin.sports-seasons.$id.surface-elo';
 
 import { logger } from '~/lib/logger';
 import { findSportsSeasonById, updateSportsSeason } from '~/models/sports-season';
-import { findParticipantsBySportsSeasonId, createParticipant } from '~/models/participant';
+import { findParticipantsBySportsSeasonId, findParticipantByName, createParticipant } from '~/models/participant';
 import {
   batchUpsertParticipantEVs,
 } from '~/models/participant-expected-value';
@@ -85,6 +85,10 @@ export async function action({ request, params }: Route.ActionArgs) {
     if (!name) {
       return { intent: 'create-participant', success: false, message: 'Name is required' } satisfies ActionData;
     }
+    const existing = await findParticipantByName(sportsSeasonId, name);
+    if (existing) {
+      return { intent: 'create-participant', success: false, message: `"${name}" already exists in this season.` } satisfies ActionData;
+    }
     const participant = await createParticipant({ sportsSeasonId, name });
     return {
       intent: 'create-participant',

database/schema.ts

@@ -311,7 +311,9 @@ export const participants = pgTable("participants", {
   expectedValue: decimal("expected_value", { precision: 10, scale: 4 }).notNull().default("0"),
   createdAt: timestamp("created_at").defaultNow().notNull(),
   updatedAt: timestamp("updated_at").defaultNow().notNull(),
-});
+}, (table) => [
+  uniqueIndex("participants_sports_season_name_unique").on(table.sportsSeasonId, table.name),
+]);
 
 export const seasonTemplateSports = pgTable("season_template_sports", {
   id: uuid("id").primaryKey().defaultRandom(),

drizzle/0064_fuzzy_wolfsbane.sql

@@ -0,0 +1 @@
+CREATE UNIQUE INDEX IF NOT EXISTS "participants_sports_season_name_unique" ON "participants" USING btree ("sports_season_id","name");

drizzle/meta/_journal.json

@@ -449,6 +449,13 @@
       "when": 1774504559479,
       "tag": "0063_bored_ultimo",
       "breakpoints": true
+    },
+    {
+      "idx": 64,
+      "version": "7",
+      "when": 1774598151282,
+      "tag": "0064_fuzzy_wolfsbane",
+      "breakpoints": true
     }
   ]
 }