feat(minigames): add custom payout math and loss-reveal helpers to shared libs

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/lib/custom-minigames/eod.ts

@@ -133,4 +133,121 @@ export function minefieldFlagsError(flags: number, mineCount: number): string |
     return "Invalid result.";
   }
   return undefined;
+}
+
+// ---------------------------------------------------------------------------
+// XP payouts
+//
+// Custom minefields pay a small share of the standard payout curve so community
+// content stays far below official play: players earn PLAYER_XP_RATE of what
+// the equivalent standard run would pay, and the field's author banks
+// CREATOR_XP_RATE of each player payout. Authors earn nothing on their own
+// fields. Numbers stay intentionally tiny.
+// ---------------------------------------------------------------------------
+
+export const PLAYER_XP_RATE = 0.1;
+export const CREATOR_XP_RATE = 0.05;
+export const XP_SCORE_DIVISOR = 50;
+export const TRAINING_BRACKET_MAX_MINES = 15;
+export const PERIMETER_BRACKET_MAX_MINES = 50;
+
+export interface CustomXpBracket {
+  baseScore: number;
+  parSeconds: number;
+}
+
+/**
+ * Reference standard difficulty for a custom field, chosen by mine count.
+ * Brackets mirror the standard EOD difficulties (see DIFFICULTIES in the EOD
+ * actions): Training Pad 9x9/10, FOB Perimeter 16x16/40, Main Supply Road 16x30/99.
+ */
+export function customXpBracket(mineCount: number): CustomXpBracket {
+  if (mineCount <= TRAINING_BRACKET_MAX_MINES) {
+    return { baseScore: 100, parSeconds: 60 };
+  }
+  if (mineCount <= PERIMETER_BRACKET_MAX_MINES) {
+    return { baseScore: 300, parSeconds: 180 };
+  }
+  return { baseScore: 600, parSeconds: 420 };
+}
+
+/** Player XP for a custom run. Losses pay nothing; wins pay 1-2 points. */
+export function customPlayerXp(input: {
+  mineCount: number;
+  seconds: number;
+  won: boolean;
+}): number {
+  if (!input.won) {
+    return 0;
+  }
+  const bracket = customXpBracket(input.mineCount);
+  const score = bracket.baseScore + Math.max(0, bracket.parSeconds - input.seconds);
+  const regularXp = Math.max(1, Math.floor(score / XP_SCORE_DIVISOR));
+  return Math.max(1, Math.floor(PLAYER_XP_RATE * regularXp));
+}
+
+/** The author's fractional bank grows by this much per player payout. */
+export function creatorBankIncrement(playerXp: number): number {
+  return CREATOR_XP_RATE * playerXp;
+}
+
+/**
+ * Adds a payout to the author's fractional bank and reports how many whole XP
+ * points are due. Whole points credit when the bank crosses 1, so a 5% share
+ * of 1-2 XP payouts still materializes over time.
+ */
+export function applyCreatorBank(
+  currentBank: number,
+  playerXp: number,
+): { bank: number; wholeXpToCredit: number } {
+  const bank = currentBank + creatorBankIncrement(playerXp);
+  const wholeXpToCredit = Math.floor(bank);
+  return { bank: bank - wholeXpToCredit, wholeXpToCredit };
+}
+
+// ---------------------------------------------------------------------------
+// Loss reveal
+// ---------------------------------------------------------------------------
+
+/**
+ * Mines that touch the exposed (revealed) area of a lost run, as linear
+ * indices. Losses reveal only these frontier mines (the caller keeps the
+ * exploded mine revealed too); the rest of the layout stays hidden because
+ * the field is static and a full reveal would leak the solution.
+ */
+export function edgeMineIndices(input: {
+  rows: number;
+  cols: number;
+  mines: number[];
+  revealed: number[];
+}): number[] {
+  const revealedSet = new Set(input.revealed);
+  const frontier: number[] = [];
+  for (const mine of input.mines) {
+    const mineRow = Math.floor(mine / input.cols);
+    const mineCol = mine % input.cols;
+    let touchesExposedArea = false;
+    for (let rowOffset = -1; rowOffset <= 1 && !touchesExposedArea; rowOffset++) {
+      for (let colOffset = -1; colOffset <= 1 && !touchesExposedArea; colOffset++) {
+        if (rowOffset === 0 && colOffset === 0) continue;
+        const neighborRow = mineRow + rowOffset;
+        const neighborCol = mineCol + colOffset;
+        if (
+          neighborRow < 0 ||
+          neighborRow >= input.rows ||
+          neighborCol < 0 ||
+          neighborCol >= input.cols
+        ) {
+          continue;
+        }
+        if (revealedSet.has(neighborRow * input.cols + neighborCol)) {
+          touchesExposedArea = true;
+        }
+      }
+    }
+    if (touchesExposedArea) {
+      frontier.push(mine);
+    }
+  }
+  return frontier;
 }

src/lib/custom-minigames/payouts.ts

@@ -0,0 +1,61 @@
+import type { Payload } from "payload";
+
+export interface CreditEodXpResult {
+  profileId: number;
+  xpEarned: number;
+}
+
+/**
+ * Credits EOD minigame XP to a user's profile, mirroring the write shape of
+ * the standard EOD action (including stripping the engine-managed
+ * `progression.xp` key). Returns null when the user has no profile.
+ *
+ * Server-side only (needs a live Payload instance); the payout math lives in
+ * the pure `custom-minigames/eod` lib.
+ */
+export async function creditEodXp(
+  payload: Payload,
+  userId: number,
+  amount: number,
+): Promise<CreditEodXpResult | null> {
+  const profileRes = await payload.find({
+    collection: "profiles",
+    where: { user: { equals: userId } },
+    limit: 1,
+    depth: 0,
+    overrideAccess: true,
+  });
+  const profile = profileRes.docs[0];
+  if (!profile) {
+    return null;
+  }
+
+  const progression = (profile.progression ?? {}) as {
+    xp?: unknown;
+    minigames?: Record<string, unknown>;
+  };
+  const { xp: _xp, ...progressionRest } = progression;
+  const minigames = progressionRest.minigames ?? {};
+  const eod = (minigames.eodMinesweeper ?? {}) as Record<string, unknown> & {
+    xpEarned?: number | null;
+  };
+  const xpEarned = (eod.xpEarned ?? 0) + amount;
+
+  await payload.update({
+    collection: "profiles",
+    id: profile.id,
+    data: {
+      progression: {
+        ...progressionRest,
+        minigames: {
+          ...minigames,
+          eodMinesweeper: { ...eod, xpEarned },
+        },
+      },
+    },
+    overrideAccess: true,
+    depth: 0,
+  });
+
+  return { profileId: profile.id, xpEarned };
+}