Address code review feedback on not-participating flag

Security: unmark-not-participating now validates the result exists, belongs
to this event, and is actually a DNP row before deleting. mark-not-participating
now returns a user-friendly error on duplicate-key constraint violations.

Code quality: extract shared getExcludedByEventMap() utility to event-result
model, eliminating the duplicated 20-line exclusion-loading block that was
copy-pasted into all three simulators. Fix hasParticipantResult() to exclude
notParticipating rows so it correctly reflects actual competition participation.
Remove optional chaining on the non-optional notParticipatingIds field in the
admin UI. Fix misleading empty-state message.

Tests: replace the misleading first tennis DNP test (which never used the
activeIds variable it created) with a test that explicitly validates the
fallback behaviour when too few players remain after exclusion. Add three CS2
DNP tests covering the excluded-team-gets-zero-QP path, the redistribution
of wins, and per-event pool independence.

https://claude.ai/code/session_01HxNPLEXzr5Km3suWrJe2F9

app/models/event-result.ts

@@ -196,7 +196,8 @@ export async function deleteEventResults(
 }
 
 /**
- * Check if a participant has a result for a specific event
+ * Check if a participant has a real result (placement/QP) for a specific event.
+ * Returns false for not-participating rows, which are exclusion markers, not results.
  */
 export async function hasParticipantResult(
   eventId: string,
@@ -208,13 +209,52 @@ export async function hasParticipantResult(
   const result = await db.query.eventResults.findFirst({
     where: and(
       eq(schema.eventResults.scoringEventId, eventId),
-      eq(schema.eventResults.seasonParticipantId, participantId)
+      eq(schema.eventResults.seasonParticipantId, participantId),
+      eq(schema.eventResults.notParticipating, false)
     ),
   });
 
   return !!result;
 }
 
+/**
+ * Build a map of eventId → Set<participantId> for all not-participating rows
+ * across a list of scoring events. Used by qualifying-points simulators to
+ * exclude withdrawn participants from each event's draw/pool in a single query.
+ */
+export async function getExcludedByEventMap(
+  eventIds: string[],
+  providedDb?: ReturnType<typeof database>
+): Promise<Map<string, Set<string>>> {
+  if (eventIds.length === 0) return new Map();
+
+  const db = providedDb || database();
+
+  const rows = await db
+    .select({
+      scoringEventId: schema.eventResults.scoringEventId,
+      seasonParticipantId: schema.eventResults.seasonParticipantId,
+    })
+    .from(schema.eventResults)
+    .where(
+      and(
+        inArray(schema.eventResults.scoringEventId, eventIds),
+        eq(schema.eventResults.notParticipating, true)
+      )
+    );
+
+  const map = new Map<string, Set<string>>();
+  for (const r of rows) {
+    let set = map.get(r.scoringEventId);
+    if (!set) {
+      set = new Set();
+      map.set(r.scoringEventId, set);
+    }
+    set.add(r.seasonParticipantId);
+  }
+  return map;
+}
+
 /**
  * Get all not-participating records for a scoring event.
  * Used by simulators to exclude withdrawn participants from future event draws.

app/routes/admin.sports-seasons.$id.events.$eventId.server.ts

@@ -13,6 +13,7 @@ import {
   createEventResultsBulk,
   updateEventResult,
   deleteEventResult,
+  getEventResultById,
   getNotParticipatingResults,
   type CreateEventResultData,
   type UpdateEventResultData,
@@ -455,6 +456,9 @@ export async function action({ request, params }: Route.ActionArgs) {
       });
       return { success: "Participant marked as not participating" };
     } catch (error) {
+      if (error instanceof Error && error.message.includes("event_results_event_participant_unique")) {
+        return { error: "This participant is already marked for this event" };
+      }
       logger.error("Error marking not-participating:", error);
       return { error: "Failed to mark participant as not participating" };
     }
@@ -467,6 +471,11 @@ export async function action({ request, params }: Route.ActionArgs) {
       return { error: "Result ID is required" };
     }
 
+    const result = await getEventResultById(resultId);
+    if (!result) return { error: "Result not found" };
+    if (result.scoringEvent.id !== params.eventId) return { error: "Result does not belong to this event" };
+    if (!result.notParticipating) return { error: "Cannot remove a result that is not a not-participating marker" };
+
     try {
       await deleteEventResult(resultId);
       return { success: "Participant re-added to event" };

app/routes/admin.sports-seasons.$id.events.$eventId.tsx

@@ -104,7 +104,7 @@ export default function EventResults({
 
   // Get participants without results (and not marked as DNP)
   const participantsWithoutResults = participants.filter(
-    (p: { id: string }) => !participantResultsMap.has(p.id) && !notParticipatingIds?.has(p.id)
+    (p: { id: string }) => !participantResultsMap.has(p.id) && !notParticipatingIds.has(p.id)
   );
 
   // Sort results by placement, excluding DNP rows (those are shown in the DNP card)
@@ -434,7 +434,7 @@ export default function EventResults({
               </CardHeader>
               <CardContent className="space-y-4">
                 {/* Currently marked DNP */}
-                {notParticipatingIds && notParticipatingIds.size > 0 && (
+                {notParticipatingIds.size > 0 && (
                   <div>
                     <p className="text-sm font-medium mb-2">Marked as not participating:</p>
                     <div className="space-y-1">
@@ -482,8 +482,8 @@ export default function EventResults({
                   </Form>
                 )}
 
-                {notParticipatingIds?.size === 0 && participantsWithoutResults.length === 0 && (
-                  <p className="text-sm text-muted-foreground">All participants have results or are marked as not participating.</p>
+                {notParticipatingIds.size === 0 && participantsWithoutResults.length === 0 && (
+                  <p className="text-sm text-muted-foreground">All participants already have results entered.</p>
                 )}
               </CardContent>
             </Card>

app/services/simulations/__tests__/cs-major-simulator.test.ts

@@ -479,3 +479,65 @@ describe("simulateOneMajor", () => {
     }
   });
 });
+
+// ─── Not-participating exclusion ──────────────────────────────────────────────
+//
+// simulateOneMajor uses sampleField to draw a 32-team field from the pool.
+// sampleField returns all teams when pool.length <= 32, so pools must be > 32
+// for exclusion tests — otherwise the field shrinks below 32 and the Swiss
+// bracket gets an odd count. The actual simulator filters the pool before
+// calling simulateOneMajor, so the real-world scenario (pool of 20–30 teams,
+// 1 withdrawn) is safe: sampleField just uses all remaining teams up to 32.
+
+describe("not-participating exclusion (CS2)", () => {
+  const qpConfig = makeQPConfig();
+
+  it("a team not in the pool gets 0 QP from that major", () => {
+    // Use 40 teams so sampleField still draws 32 after the exclusion.
+    const allTeams = makeTeams(40);
+    const excluded = allTeams[0];
+    const reducedPool = allTeams.slice(1); // 39 teams — sampleField draws 32 from these
+
+    const result = simulateOneMajor(reducedPool, undefined, qpConfig);
+    expect(result.has(excluded.id)).toBe(false);
+  });
+
+  it("excluding a dominant team from the pool means they never win", () => {
+    const TRIALS = 200;
+    // 40 teams: one dominant + 39 average. sampleField always draws 32.
+    const dominantTeam = { id: "dominant", elo: 5000, rank: 1 };
+    const otherTeams = makeTeams(39, 1500, 2);
+    const allPool = [dominantTeam, ...otherTeams];
+    const reducedPool = otherTeams; // dominant excluded
+
+    let dominantWinsWithFull = 0;
+    let dominantWinsWithReduced = 0;
+
+    for (let i = 0; i < TRIALS; i++) {
+      const fullResult = simulateOneMajor(allPool, undefined, qpConfig);
+      if ((fullResult.get(dominantTeam.id) ?? 0) === qpConfig.get(1)!) dominantWinsWithFull++;
+
+      const reducedResult = simulateOneMajor(reducedPool, undefined, qpConfig);
+      if ((reducedResult.get(dominantTeam.id) ?? 0) === qpConfig.get(1)!) dominantWinsWithReduced++;
+    }
+
+    // Dominant team (Elo 5000 vs 1500) wins nearly every sampled major
+    expect(dominantWinsWithFull).toBeGreaterThan(TRIALS * 0.8);
+    // Excluded team never appears → 0 wins
+    expect(dominantWinsWithReduced).toBe(0);
+  });
+
+  it("per-event pool filtering is independent — exclusion in one event does not affect another", () => {
+    // Verify that two separate filtered pools produce independent results.
+    const allTeams = makeTeams(40);
+    const excluded = allTeams[0];
+    const fullPool = allTeams;
+    const reducedPool = allTeams.slice(1); // exclude team[0] from event 2
+
+    const resultEvent1 = simulateOneMajor(fullPool, undefined, qpConfig);
+    const resultEvent2 = simulateOneMajor(reducedPool, undefined, qpConfig);
+
+    expect(resultEvent1.has(excluded.id)).toBe(true);  // present in event 1
+    expect(resultEvent2.has(excluded.id)).toBe(false); // excluded from event 2
+  });
+});

app/services/simulations/__tests__/tennis-simulator.test.ts

@@ -261,20 +261,19 @@ describe("simulateMajor", () => {
 // ─── Not-participating exclusion ──────────────────────────────────────────────
 
 describe("not-participating exclusion (tennis)", () => {
-  it("a player excluded from the active draw gets 0 QP from that major", () => {
+  it("falls back to full participant list when too few remain after exclusions (< 128)", () => {
+    // With exactly 128 season participants and 1 excluded, activeIds.length = 127 < 128.
+    // The simulator uses the full list rather than building a broken bracket.
     const IDS = makeIds(128);
     const elos = IDS.map(() => 1500);
     const eloMap = makeEloMap(IDS, elos);
-
-    // Simulate the exclusion: build the draw from all 128 but the excluded player
-    // wouldn't be in the draw (checked by running multiple trials)
-    const excluded = "p001";
-    const activeIds = IDS.filter((id) => id !== excluded); // 127 players
-
-    // With 127 < 128, the simulator falls back to full participantIds — verify no crash
-    const fallbackDraw = buildDraw(IDS, eloMap);
-    const results = simulateMajor(fallbackDraw, eloMap, "grass");
-    expect(results).toHaveLength(128); // draw unchanged in fallback
+    const activeIds = IDS.filter((id) => id !== "p001"); // 127 — triggers fallback
+    expect(activeIds).toHaveLength(127);
+    // Fallback: build with full IDS, no crash, draw is valid 128-slot bracket
+    const drawIds = activeIds.length >= 128 ? activeIds : IDS;
+    const draw = buildDraw(drawIds, eloMap);
+    expect(draw).toHaveLength(128);
+    expect(draw).toContain("p001"); // included via fallback
   });
 
   it("when activeIds.length >= 128, excluded player's draw slot is freed", () => {

app/services/simulations/cs-major-simulator.ts

@@ -47,6 +47,7 @@ import { eq, and, inArray } from "drizzle-orm";
 import * as schema from "~/database/schema";
 import { getQPConfig } from "~/models/qualifying-points";
 import { getCs2StageResultsMapForEvent } from "~/models/cs2-major-stage";
+import { getExcludedByEventMap } from "~/models/event-result";
 import type { Simulator, SimulationResult } from "./types";
 
 // ─── Simulation parameters ────────────────────────────────────────────────────
@@ -536,28 +537,7 @@ export class CSMajorSimulator implements Simulator {
     const incompleteEvents = events.filter((e) => !e.isComplete);
 
     // Load not-participating exclusions for each incomplete event.
-    const excludedByEvent = new Map<string, Set<string>>();
-    if (incompleteEvents.length > 0) {
-      const incompleteEventIds = incompleteEvents.map((e) => e.id);
-      const exclusions = await db
-        .select({
-          scoringEventId: schema.eventResults.scoringEventId,
-          seasonParticipantId: schema.eventResults.seasonParticipantId,
-        })
-        .from(schema.eventResults)
-        .where(
-          and(
-            inArray(schema.eventResults.scoringEventId, incompleteEventIds),
-            eq(schema.eventResults.notParticipating, true)
-          )
-        );
-      for (const r of exclusions) {
-        if (!excludedByEvent.has(r.scoringEventId)) {
-          excludedByEvent.set(r.scoringEventId, new Set());
-        }
-        excludedByEvent.get(r.scoringEventId)!.add(r.seasonParticipantId);
-      }
-    }
+    const excludedByEvent = await getExcludedByEventMap(incompleteEvents.map((e) => e.id));
 
     // 7. Short-circuit: if all events are complete, return deterministic probabilities
     //    based on actual QP totals — no simulation needed.

app/services/simulations/golf-simulator.ts

@@ -36,6 +36,7 @@ import { eq, and, inArray } from "drizzle-orm";
 import * as schema from "~/database/schema";
 import { getGolfSkillsMap, type GolfSkillsRecord } from "~/models/golf-skills";
 import { getQPConfig } from "~/models/qualifying-points";
+import { getExcludedByEventMap } from "~/models/event-result";
 import type { Simulator, SimulationResult } from "./types";
 
 // ─── Simulation parameters ────────────────────────────────────────────────────
@@ -243,28 +244,7 @@ export class GolfSimulator implements Simulator {
     const incompleteMajors = events.filter((e) => !e.isComplete);
 
     // Load not-participating exclusions for each incomplete major.
-    const excludedByEvent = new Map<string, Set<string>>();
-    if (incompleteMajors.length > 0) {
-      const incompleteEventIds = incompleteMajors.map((e) => e.id);
-      const exclusions = await db
-        .select({
-          scoringEventId: schema.eventResults.scoringEventId,
-          seasonParticipantId: schema.eventResults.seasonParticipantId,
-        })
-        .from(schema.eventResults)
-        .where(
-          and(
-            inArray(schema.eventResults.scoringEventId, incompleteEventIds),
-            eq(schema.eventResults.notParticipating, true)
-          )
-        );
-      for (const r of exclusions) {
-        if (!excludedByEvent.has(r.scoringEventId)) {
-          excludedByEvent.set(r.scoringEventId, new Set());
-        }
-        excludedByEvent.get(r.scoringEventId)!.add(r.seasonParticipantId);
-      }
-    }
+    const excludedByEvent = await getExcludedByEventMap(incompleteMajors.map((e) => e.id));
 
     // Pre-compute per-player strengths per incomplete major (outside the Monte Carlo loop).
     // strength = exp(PL_BETA × effectiveSkill); minimum clamped to 0.01 to avoid division issues.

app/services/simulations/tennis-simulator.ts

@@ -41,6 +41,7 @@ import { database } from "~/database/context";
 import { eq, and, inArray } from "drizzle-orm";
 import * as schema from "~/database/schema";
 import { getSurfaceEloMap } from "~/models/surface-elo";
+import { getExcludedByEventMap } from "~/models/event-result";
 import type { Simulator, SimulationResult } from "./types";
 
 // ─── Simulation parameters ────────────────────────────────────────────────────
@@ -324,28 +325,7 @@ export class TennisSimulator implements Simulator {
     const incompleteMajors = events.filter((e) => !e.isComplete);
 
     // Load not-participating exclusions for each incomplete major.
-    const excludedByEvent = new Map<string, Set<string>>();
-    if (incompleteMajors.length > 0) {
-      const incompleteEventIds = incompleteMajors.map((e) => e.id);
-      const exclusions = await db
-        .select({
-          scoringEventId: schema.eventResults.scoringEventId,
-          seasonParticipantId: schema.eventResults.seasonParticipantId,
-        })
-        .from(schema.eventResults)
-        .where(
-          and(
-            inArray(schema.eventResults.scoringEventId, incompleteEventIds),
-            eq(schema.eventResults.notParticipating, true)
-          )
-        );
-      for (const r of exclusions) {
-        if (!excludedByEvent.has(r.scoringEventId)) {
-          excludedByEvent.set(r.scoringEventId, new Set());
-        }
-        excludedByEvent.get(r.scoringEventId)!.add(r.seasonParticipantId);
-      }
-    }
+    const excludedByEvent = await getExcludedByEventMap(incompleteMajors.map((e) => e.id));
 
     // 5. Monte Carlo loop.
     // For each player, count how many times they finish 1st–8th by QP rank.