Add complete CS2 event reset to clear orphaned results/QP

The CS2 Major EV simulation silently discarded the Champions Stage
bracket for IEM Cologne 2026: the bracket seeded "Team Spirit" in QF1
while the stage assignments listed the (different) "Spirit Academy", so
the realBracket gate found an out-of-field participant and rejected the
whole bracket. The phantom "Spirit Academy" also left a stray
event_results row (33 rows for 32 teams).

The existing "Reset all" button only cleared cs2_major_stage_results, so
re-entering couldn't remove the phantom result or its cached QP total.

Add resetCs2Event, which also deletes the event's event_results and
recomputes the affected participants' cached QP totals — all inside a
single transaction so a mid-operation failure can't leave the event in a
torn state. It deliberately preserves the Champions Stage bracket so
re-entry realigns the stage data to it. The reset button now confirms
and states that results/QP are cleared too.

Tests: resetCs2Event clear+recompute behavior, and a simulator
regression pinning that one out-of-field QF participant disables the
whole bracket.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/models/__tests__/cs2-major-stage.test.ts

@@ -1,6 +1,17 @@
-import { describe, it, expect } from "vitest";
-import { computeStage3ExitQP } from "../cs2-major-stage";
-import { calculateSplitQualifyingPoints } from "../qualifying-points";
+import { describe, it, expect, vi } from "vitest";
+
+// Stub only the cached-total recompute so resetCs2Event can be exercised without
+// a real DB; the rest of qualifying-points stays real for the pure-function tests.
+vi.mock("../qualifying-points", async (importOriginal) => {
+  const actual = await importOriginal();
+  return {
+    ...(actual as Record<string, unknown>),
+    recalculateParticipantQP: vi.fn(),
+  };
+});
+
+import { computeStage3ExitQP, resetCs2Event } from "../cs2-major-stage";
+import { calculateSplitQualifyingPoints, recalculateParticipantQP } from "../qualifying-points";
 
 function makeStage3QPConfig(): Map<number, number> {
   const config = new Map<number, number>();
@@ -257,3 +268,57 @@ describe("Champions Stage floor QP calculation", () => {
     expect(floorQP).toBeCloseTo((10 + 8 + 6 + 4) / 4); // = 7
   });
 });
+
+describe("resetCs2Event", () => {
+  /**
+   * Build a mock db whose `transaction` runs its callback with the same handle
+   * (so the deletes + recalcs run inline), capturing which tables were deleted.
+   * The eventResults SELECT returns `resultRows`.
+   */
+  function makeMockDb(resultRows: Array<{ participantId: string }>) {
+    const deletedTables: unknown[] = [];
+    const db: Record<string, unknown> = {
+      select: vi.fn(() => ({
+        from: vi.fn(() => ({ where: vi.fn().mockResolvedValue(resultRows) })),
+      })),
+      delete: vi.fn((table: unknown) => {
+        deletedTables.push(table);
+        return { where: vi.fn().mockResolvedValue(undefined) };
+      }),
+    };
+    db.transaction = vi.fn(async (cb: (tx: unknown) => unknown) => cb(db));
+    return { db, deletedTables };
+  }
+
+  it("clears assignments + results and recomputes each distinct participant's QP total", async () => {
+    vi.mocked(recalculateParticipantQP).mockClear();
+    // Two participants, one duplicated across rows → recompute exactly twice.
+    const { db, deletedTables } = makeMockDb([
+      { participantId: "p1" },
+      { participantId: "p1" },
+      { participantId: "p2" },
+    ]);
+
+    await resetCs2Event("event-1", "season-1", db as never);
+
+    // Both the stage-results table and the event-results table were deleted,
+    // inside the transaction.
+    expect((db as Record<string, ReturnType<typeof vi.fn>>).transaction).toHaveBeenCalledTimes(1);
+    expect(deletedTables).toHaveLength(2);
+
+    const recalcCalls = vi.mocked(recalculateParticipantQP).mock.calls;
+    expect(recalcCalls).toHaveLength(2);
+    expect(recalcCalls.map((c) => c[0]).sort()).toEqual(["p1", "p2"]);
+    for (const call of recalcCalls) expect(call[1]).toBe("season-1");
+  });
+
+  it("still clears the event when there are no recorded results", async () => {
+    vi.mocked(recalculateParticipantQP).mockClear();
+    const { db, deletedTables } = makeMockDb([]);
+
+    await resetCs2Event("event-1", "season-1", db as never);
+
+    expect(deletedTables).toHaveLength(2);
+    expect(recalculateParticipantQP).not.toHaveBeenCalled();
+  });
+});

app/models/cs2-major-stage.ts

@@ -13,9 +13,10 @@
  */
 
 import { database } from "~/database/context";
-import { cs2MajorStageResults, seasonParticipants } from "~/database/schema";
+import { cs2MajorStageResults, seasonParticipants, eventResults } from "~/database/schema";
 import { eq, and, sql } from "drizzle-orm";
-import { getQPConfig, calculateSplitQualifyingPoints, writeEventResultsQP } from "~/models/qualifying-points";
+import { getQPConfig, calculateSplitQualifyingPoints, writeEventResultsQP, recalculateParticipantQP } from "~/models/qualifying-points";
+import { deleteEventResults } from "~/models/event-result";
 
 export interface Cs2StageResult {
   id: string;
@@ -126,14 +127,57 @@ export async function upsertCs2StageAssignments(
  * Called when the admin resets the event setup.
  */
 export async function clearCs2StageAssignments(
-  scoringEventId: string
+  scoringEventId: string,
+  providedDb?: ReturnType<typeof database>
 ): Promise<void> {
-  const db = database();
+  const db = providedDb || database();
   await db
     .delete(cs2MajorStageResults)
     .where(eq(cs2MajorStageResults.scoringEventId, scoringEventId));
 }
 
+/**
+ * Fully reset a CS2 Major event so it can be set up again from scratch.
+ *
+ * Clears more than stage assignments alone: it also removes every recorded
+ * result for the event and recomputes the cached QP totals of the affected
+ * participants. This matters because a stale stage assignment can leave a
+ * phantom participant (e.g. an academy team entered in place of the main
+ * roster) with provisional QP in event_results and a cached total that would
+ * otherwise survive a stage-only reset and keep polluting the standings and
+ * the EV simulation field.
+ *
+ * Deliberately does NOT touch the Champions-Stage bracket (playoffMatches) —
+ * re-entry realigns the stage data to the existing bracket.
+ */
+export async function resetCs2Event(
+  scoringEventId: string,
+  sportsSeasonId: string,
+  providedDb?: ReturnType<typeof database>
+): Promise<void> {
+  const db = providedDb || database();
+
+  // Capture participants with results first so we can recompute their cached
+  // QP totals after the rows are deleted (mirrors deleteScoringEvent).
+  const existing = await db
+    .select({ participantId: eventResults.seasonParticipantId })
+    .from(eventResults)
+    .where(eq(eventResults.scoringEventId, scoringEventId));
+  const affectedParticipantIds = [...new Set(existing.map((r) => r.participantId))];
+
+  // Delete + recompute atomically so a mid-operation failure can't leave the
+  // event torn (e.g. assignments gone but stale QP totals surviving in the
+  // standings) — the exact phantom-QP state this reset exists to clear.
+  await db.transaction(async (tx) => {
+    await clearCs2StageAssignments(scoringEventId, tx);
+    await deleteEventResults(scoringEventId, tx);
+
+    for (const participantId of affectedParticipantIds) {
+      await recalculateParticipantQP(participantId, sportsSeasonId, tx);
+    }
+  });
+}
+
 /**
  * Mark teams as eliminated from a specific stage.
  * Each elimination entry specifies which stage the team was eliminated at —

app/routes/admin.sports-seasons.$id.events.$eventId.cs2-setup.tsx

@@ -8,7 +8,7 @@ import {
   getCs2StageResultsForEvent,
   upsertCs2StageAssignments,
   markCs2StageEliminations,
-  clearCs2StageAssignments,
+  resetCs2Event,
   clearCs2EliminationsAtStage,
   assignCs2EliminationQP,
 } from '~/models/cs2-major-stage';
@@ -62,8 +62,8 @@ export async function action({ request, params }: Route.ActionArgs) {
   const intent = formData.get('intent') as string;
 
   if (intent === 'reset') {
-    await clearCs2StageAssignments(eventId);
-    return { success: true, message: 'Stage assignments cleared.' };
+    await resetCs2Event(eventId, params.id);
+    return { success: true, message: 'Stage assignments and recorded results cleared.' };
   }
 
   if (intent === 'assign') {
@@ -268,7 +268,14 @@ export default function AdminCs2Setup() {
           <CardTitle className="flex items-center justify-between">
             Stage Assignments
             {stageResults.length > 0 && (
-              <Form method="post">
+              <Form
+                method="post"
+                onSubmit={(e) => {
+                  if (!confirm('Reset this event? This clears all stage assignments AND recorded results/QP for the event so you can set it up again. The Champions Stage bracket is kept.')) {
+                    e.preventDefault();
+                  }
+                }}
+              >
                 <input type="hidden" name="intent" value="reset" />
                 <Button type="submit" variant="ghost" size="sm" className="text-destructive">
                   <Trash2 className="h-4 w-4 mr-1" />

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

@@ -728,6 +728,31 @@ describe("simulateChampionsStage honoring a real bracket", () => {
     // foreign bracket (which would have forced its own — absent — winner).
     expect(aWins / 500).toBeGreaterThan(0.25);
   });
+
+  it("discards the whole bracket when a single QF participant is not in the field", () => {
+    // Regression for IEM Cologne 2026: the Champions field held "Spirit Academy"
+    // while the bracket seeded the (different) "Team Spirit" participant in QF1.
+    // The realBracket gate is all-or-nothing, so one out-of-field participant
+    // makes the entire bracket — including the 3 valid completed QFs — be ignored
+    // and the stage falls back to Elo seeding. (When this changes to per-match
+    // honoring, update this test deliberately.)
+    const teams = makeChampTeams();
+    const bracket = makeFullBracket().map((mm) =>
+      mm.round === "Quarterfinals" && mm.matchNumber === 1
+        ? { ...mm, participant1Id: "ghost-not-in-field" }
+        : mm
+    );
+
+    let hWins = 0; // h wins everything if (and only if) the bracket is honored.
+    for (let i = 0; i < 500; i++) {
+      const result = simulateChampionsStage(teams, bracket);
+      expect(result.placements.size).toBe(8);
+      if (result.placements.get("h") === 1) hWins++;
+    }
+    // Weakest team h would be champion every run if the bracket applied; under
+    // Elo fallback it wins far less than the ~1.0 a honored bracket would force.
+    expect(hWins / 500).toBeLessThan(0.5);
+  });
 });
 
 // ─── simulateOneMajor full conditioning (stages + bracket + recorded QP) ──────